Direct tests of T, CP, CPT symmetries in transitions of neutral K mesons with the KLOE experiment
D. Babusci, M. Berłowski, C. Bloise, F. Bossi, P. Branchini, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwiński, G. D'Agostini, R. D'Amico, E. Dane, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Domenico, E. Diociaiuti, D. Domenici, A. D'Uffizi, G. Fantini, A. Gajos, S. Gamrat, P. Gauzzi, S. Giovannella, E. Graziani, X. Kang, A. Kupść, G. Mandaglio, M. Martini, S. Miscetti, P. Moskal, A. Passeri, E. Pérez del Río, M. Schioppa, A. Selce, M. Silarski, F. Sirghi, E.P. Solodov, W. Wiślicki, M. Wolke, J. Bernabéu
abstract
Tests of the T, CPand CPTsymmetries in the neutral kaon system are performed by the direct comparison of the probabilities of a kaon transition process to its symmetry-conjugate. The exchange of inand outstates required for a genuine test involving an antiunitary transformation implied by time-reversal is implemented exploiting the entanglement of K0K0 pairs produced at a ?-factory.
A data sample collected by the KLOE experiment at DAFNE corresponding to an integrated luminosity of about 1.7 fb?1 is analysed to study the Dt distributions of the ??KSKL??+????e??and ??KSKL???e??3?0 processes, with Dt the difference of the kaon decay times. A comparison of the measured Dt distributions in the asymptotic region Dt>>t? Sallows to test for the first time T and CPT symmetries in kaon transitions with a precision of few percent, and to observe CP violation with this novel method.
Precision tests of quantum mechanics and CPT symmetry with entangled neutral kaons at KLOE
D. Babusci, M. Berlowski, C. Bloise, F. Bossi, P. Branchini, A. Budano, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwiński, G. D'Agostini, E. Dane, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, E. Diociaiuti, D. Domenici, A. D'Uffizi, A. Fantini, G. Fantini, P. Fermani, S. Fiore, A. Gajos, P. Gauzzi, S. Giovannella, E. Graziani, V. L. Ivanov, T. Johansson, X. Kang, D. Kisielewska-Kamińska, E. A. Kozyrev, W. Krzemien, A. Kupsc, P. A. Lukin, G. Mandaglio, M. Martini, R. Messi, S. Miscetti, D. Moricciani, P. Moskal, A. Passeri, V. Patera, E. Perez del Rio, P. Santangelo, M. Schioppa, A. Selce, M. Silarski, F. Sirghi, E. P. Solodov, L. Tortora, G. Venanzoni, W. Wiślicki, M. Wolke
abstract
The quantum interference between the decays of entangled neutral kaons is studied in the process phi -> KSKL -> pi(+)pi(-)pi(+)pi(-), which exhibits the characteristic Einstein-Podolsky-Rosen correlations that prevent both kaons to decay into pi(+)pi(-) at the same time. This constitutes a very powerful tool for testing at the utmost precision the quantum coherence of the entangled kaon pair state, and to search for tiny decoherence and CPT violation effects, which may be justified in a quantum gravity framework.
The analysed data sample was collected with the KLOE detector at DAFNE, the Frascati phi-factory, and corresponds to an integrated luminosity of about 1.7 fb(-1), i.e. to about 1.7 x 10(9) phi -> KSKL decays produced. From the fit of the observed Delta t distribution, being Delta t the difference of the kaon decay times, the decoherence and CPT violation parameters of various phenomenological models are measured with a largely improved accuracy with respect to previous analyses.
The results are consistent with no deviation from quantum mechanics and CPT symmetry, while for some parameters the precision reaches the interesting level at which - in the most optimistic scenarios - quantum gravity effects might show up. They provide the most stringent limits up to date on the considered models.
Upper limit on the eta->pi+pi- branching fraction with the KLOE experiment
D. Babusci, M. Berlowski, C. Bloise, F. Bossi, P. Branchini, A. Budano, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwiński, G. D'Agostini, E. Dan?, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, D. Domenici, A. D'Uffizi, A. Fantini, P. Fermani, S. Fiore, A. Gajos, P. Gauzzi, S. Giovannella, E. Graziani, V. L. Ivanov, T. Johansson, X. Kang, D. Kisielewska-Kamińska, E. A. Kozyrev, W. Krzemien, A. Kupsc, P. A. Lukin, G. Mandaglio, M. Martini, R. Messi, S. Miscetti, D. Moricciani, P. Moskal, S. Parzych, A. Passeri, V. Patera, E. Perez del Rio, P. Santangelo, M. Schioppa, A. Selce, M. Silarski, F. Sirghi, E. P. Solodov, L. Tortora, G. Venanzoni, W. Wiślicki, M. Wolke
abstract
Based on an integrated luminosity of 1.61 fb^{-1} e+e- collision data collected with the KLOE detector at DAFNE, the Frascati phi-factory, a search for the P- and CP-violating decay eta->pi+pi- has been performed. Radiative phi->eta gamma decay is exploited to access the eta mesons. No signal is observed in the pi+pi- invariant mass spectrum, and the upper limit on the branching fraction at 90% confidence level is determined to be B(eta->pi+pi-)<4.9x10^{-6}, which is approximately three times smaller than the previous KLOE result. From the combination of these two measurements we get B(eta->pi+pi-)<4.4x10^{-6} at 90% confidence level.
The cylindrical-GEM inner tracker detector of the KLOE-2 experiment
G.Bencivenni, ..., E. Czerwiński, et al.
abstract
A new tracking device, the Inner Tracker, was installed at the interaction region of KLOE-2 and it was operated together with the Drift Chamber to improve track and vertex reconstruction capabilities of the new experimental apparatus. The Inner Tracker is a four-layer cylindrical triple-GEM detector with each layer equipped with an X-V strips-pads stereo readout. Although GEM detectors have been extensively used in high energy physics experiments, the IT, with its fully-cylindrical geometry is a frontier detector and KLOE-2 is the first experiment which benefited of this novel detector technology operated at a collider.
The operation of the Inner Tracker will be presented, together with the results of the alignment and calibration and tracking?vertexing performance of such a unique detector.
Measurement of the branching fraction for the decay KS -> pi mu nu with the KLOE detector
D. Babusci, M. Berlowski, C. Bloise, F. Bossi, P. Branchini, A. Budano, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwisnski, G. D'Agostini, E. Dane, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, D. Domenici, A. D'Uffizi, A. Fantini, P. Fermani, S. Fiore, A. Gajos, P. Gauzzi, S. Giovannella, E. Graziani, V. L. Ivanov, T. Johansson, X. Kang, D. Kisielewska-Kamisnska, E. A. Kozyrev, W. Krzemien, A. Kupsc, P. A. Lukin, G. Mandaglio, M. Martini, R. Messi, S. Miscetti, D. Moricciani, P. Moskal, S. Parzych, A. Passeri, V. Patera, E. Perez del Rio, P. Santangelo, M. Schioppa, A. Selce, M. Silarski, F. Sirghi, E. P. Solodov, L. Tortora, G. Venanzoni, W. Wislicki, M. Wolke
abstract
Based on a sample of 300 million KS mesons produced in phi -> KLKS decays recorded by the KLOE experiment at the DAFNE e+e- collider we have measured the branching fraction for the decay KS -> pi mu nu. The KS mesons are identified by the interaction of KL mesons in the detector. The KS -> pi mu nu decays are selected by a boosted decision tree built with kinematic variables and by a time-of-flight measurement. Signal efficiencies are evaluated with data control samples of KL -> pi mu nu decays. A fit to the reconstructed muon mass distribution finds 7223?180 signal events. Normalising to the KS -> pi+ pi- decay events the result for the branching fraction is B(KS -> pi mu nu) = (4.56+-0.11stat+-0.17syst)×10-4.
Application of multivariate analysis in search of the Ks->3pi0 decay in the KLOE experiment
S. Parzych
abstract
According to the Standard Model, one of the purely CP-violating processes is the never observed KS->3pi0 decay. The best upper limit on the branching ratio of this process BR(KS->3p0)<2.6×10^-8 was obtained in the KLOE experiment using cut-based analysis. In this paper, we show preliminary results of an alternative approach to those studies using multivariate analysis methods.
Measurement of the charge asymmetry for the KS->pi e nu decay and test of CPT symmetry with the KLOE detector
The KLOE-2 collaboration: A. Anastasi, E. Czerwiński, A. Gajos, D. Kisielewska-Kamińska, W. Krzemień, P. Moskal, M. Silarski, W. Wiślicki, et al.
abstract
Using 1.63 fb^(-1) of integrated luminosity collected by the KLOE experiment about 7 10^4 KS->pi e nu decays have been reconstructed. The measured value of the charge asymmetry for this decay is AS=(-4.9 pm 5.7_{stat} pm 2.6_{syst}) 10^(-3), which is almost twice more precise than the previous KLOE result. The combination of these two measurements gives AS=(-3.8 pm 5.0_{stat} pm 2.6_{syst}) 10^(-3) and, together with the asymmetry of the KL semileptonic decay, provides significant tests of the CPT symmetry. The obtained results are in agreement with CPT invariance.
Strong interaction between kaons in the reactions e+e- -> K+K- gamma and e+ e- ->K0K0gamma
L. Leśniak, F. Sobczuk, M. Silarski, and F. Morawski
abstract
A theoretical model of the reactions e+e- -> K+K-gamma and e+e- -> K0K0gamma has been derived. The strong interaction between kaons is taken into account using a general form of the KK scattering amplitude. It is shown that some models formulated in the past are particular cases of the present approach. The formulas for the K+K- effective mass dependence of the differential cross section as well as for the angular kaon and photon distributions and for the branching fractions of the phi(1020) -> K-K+gamma and phi(1020) -> K0K0-gamma decays have been obtained. We present numerical results for the functions entering into transition amplitudes, KK? effective mass distributions, total cross sections, and branching fractions. Finally, the model is generalized to treat other reactions with two pseudoscalar mesons accompanying a photon in the final state.
Combined limit on the production of a light gauge boson decaying into mu+ mu- and pi+pi-
The KLOE-2 collaboration: A. Anastasi, E. Czerwiński, A. Gajos, D. Kisielewska-Kamińska, W. Krzemień, P. Moskal, M. Silarski, W. Wiślicki, et al.
abstract
We searched for the decay of a light vector gauge boson, also known as dark photon, in the process by means of the Initial State Radiation (ISR) method. We used 1.93 fb^-1 of data collected by the KLOE experiment at the DAFNE phi-factory. No structures have been observed over the irreducible background. A 90% CL limit on the ratio between the dark coupling constant and the fine structure constant of has been set in the dark photon mass region between 519 MeV and 973 MeV. This new limit has been combined with the published result obtained investigating the hypothesis of the dark photon decaying into hadrons in events. The combined 90% CL limit increases the sensitivity especially in the rho-omega interference region and excludes greater than . For dark photon masses greater than 600 MeV the combined limit is lower than 8 resulting more stringent than present constraints from other experiments.
Combination of KLOE sigma(e^+e^- e -> pi^+pi^-g(g)) measurements and determination of a_{mu)^{pi^+pi^-} in the energy range 0.10 < s < 0.95 GeV^2
The KLOE-2 collaboration: A. Anastasi, E. Czerwiński, A. Gajos, D. Kisielewska-Kamińska, W. Krzemień, P. Moskal, M. Silarski, W. Wiślicki, et al.
abstract
The three precision measurements of the cross section sigma(e^+e^- e -> pi^+pi^-g(g)) using initial state radiation by the KLOE collaboration provide an important input for the prediction of the hadronic contribution to the anomalous magnetic moment of the muon. These measurements are correlated for both statistical and systematic uncertainties and, therefore, the simultaneous use of these measurements requires covariance matrices that fully describe the correlations. We present the construction of these covariance matrices and use them to determine a combined KLOE measurement for sigma(e^+e^- e -> pi^+pi^-g(g)). We find, from this combination, a two-pion contribution to the muon magnetic anomaly in the energy range 0.10 < s < 0.95 GeV^2 of a_{mu)^{pi^+pi^-} = (489.8 pm 1.7 stat pm 4.8 sys ) 10^(-10) .
Tests of discrete symmetries and quantum coherence with neutral kaons at the KLOE-2 experiment
A. Gajos
abstract
The KLOE-2 detector records decays of quantum-entangled pairs of neutral kaons produced in decays of ? mesons provided by the DA?NE accelerator at the Laboratori Nazionali di Frascati, Italy. This system allows for a broad range of studies of fundamental discrete symmetries including tests which are only feasible with entangled neutral mesons. This work reports on the Lorentz non-invariance and CPT violation searches with the ? ? KSKL ? ?+???+?? process in the framework of the Standard Model Extension. Moreover, status and results of quantum coherence tests with the same process are discussed. Finally, the status of ongoing direct tests of T and CPT in neutral kaon transitions is presented. For each of the reported studies, perspectives are discussed for the KLOE-2 experiment, which is presently taking data.
The cylindrical GEM detector of the KLOE-2 experiment
G. Bencivenni, P. Branchini, P. Ciambrone, E. Czerwinski, E. De Lucia, A. Di Cicco D. Domenici, G. Felici, P. Fermani and G. Morello
abstract
The KLOE-2 experiment started its data taking campaign in November 2014 with an upgraded tracking system at the DA?NE electron-positron collider at the Frascati National Laboratory of INFN. The new tracking device, the Inner Tracker, operated together with the KLOE-2 Drift Chamber, has been installed to improve track and vertex reconstruction capabilities of the experimental apparatus. The Inner Tracker is a cylindrical GEM detector composed of four cylindrical triple-GEM detectors, each provided with an X-V strips-pads stereo readout. Although GEM detectors are already used in high energy physics experiments, this device is considered a frontier detector due to its fully-cylindrical geometry: KLOE-2 is the first experiment benefiting of this novel detector technology. Alignment and calibration of this detector will be presented together with its operating performance and reconstruction capabilities.
Recent results and perspectives with KLOE-2
E. Czerwiński for the KLOE-2 Collaboration
abstract
In this paper we summarize the recent experimental results from KLOE-2 on the dark photon search in the e+e??U? , U??+?? , measurement of Branching Ratio and Transition Form Factor of ???0e+e? decay, Dalitz plot analysis of ???+???0 process and CPT symmetry and Lorentz invariance test with entangled K mesons. Additionally a discussion about ongoing test of CPT symmetry via measurement of K S charge asymmetry is included together with description of the KLOE-2 detection system.
The KLOE-2 Inner Tracker: Detector commissioning and operation
A. Balla, G. Bencivenni, P. Branchini, P. Ciambrone, E. Czerwinski, E. De Lucia, A. Cicco, D. Di Domenici, G. Felici, G. Morello
abstract
The KLOE-2 experiment started its data taking campaign in November 2014 with an upgraded tracking system including an Inner Tracker built with the cylindrical GEM technology, to operate together with the Drift Chamber improving the apparatus tracking performance. The Inner Tracker is composed of four cylindrical triple-GEM, each provided with an X?V strips-pads stereo readout and equipped with the GASTONE ASIC developed inside the KLOE-2 collaboration. Although GEM detectors are already used in high energy physics experiment, this device is considered a frontier detector due to its cylindrical geometry: KLOE-2 is the first experiment to use this novel solution. The results of the detector commissioning, detection efficiency evaluation, calibration studies and alignment, both with dedicated cosmic-ray muon and Bhabha scattering events, will be reported.
Measurement of the running of the fine structure constant below 1 GeV with the KLOE detector
KLOE-2 Collaboration: A. Anastasi, E. Czerwiński, A. Gajos, D. Kamińska, W. Krzemień, P. Moskal, M. Silarski, W. Wiślicki, et al.
abstract
We have measured the running of the effective QED coupling constant alpha(s) in the time-like region 0.6
Limit on the production of a new vector boson in e+e- -> Ug, U -> pi+pi- with the KLOE experiment
KLOE-2 Collaboration: A. Anastasi, E. Czerwiński, A. Gajos, D. Kamińska, W. Krzemień, P. Moskal, M. Silarski, W. Wiślicki et al.
abstract
The recent interest in a light gauge boson in the framework of an extra U(1) symmetry motivates searches in the mass range below 1 GeV. We present a search for such a particle, the dark photon, in e+e->Ug , U->pi+pi- based on 28 million e+e->pi+pi-g events collected at DAFNE by the KLOE experiment. The pi+pi- production by initial-state radiation compensates for a loss of sensitivity of previous KLOE U->e+e-, mu+mu- searches due to the small branching ratios in the rho-omega resonance region. We found no evidence for a signal and set a limit at 90% CL on the mixing strength between the photon and the dark photon, epsilon^2 , in the U mass range between 527 and 987MeV . Above 700 MeV this new limit is more stringent than previous ones.
Precision measurement of the eta to pi+pi-pi0 Dalitz plot distribution with the KLOE detector
KLOE-2 Collaboration: A. Anastasi, E. Czerwiński, A. Gajos, D. Kamińska, W. Krzemień, P. Moskal, M. Silarski, W. Wiślicki, et al.
abstract
Using 1.6 fb^-1 of e+e-to phi eta gamma data collected with the KLOE detector at DAFNE, the Dalitz plot distribution for the eta to pi+ pi- pi0 decay is studied with the world's largest sample of ~4.7 10^6 events. The Dalitz plot density is parametrized as a polynomial expansion up to cubic terms in the normalized dimensionless variables X and Y. The experiment is sensitive to all charge conjugation conserving terms of the expansion, including a gX2Y term. The statistical uncertainty of all parameters is improved by a factor two with respect to earlier measurements.
Measurement of the phi->pi0e+e- transition form factor with the KLOE detector
KLOE-2 Collaboration: A. Anastasi, E. Czerwiński, A. Gajos, D. Kamińska, W. Krzemień, P. Moskal, M. Silarski, W. Wiślicki, et al.
abstract
A measurement of the vector to pseudoscalar conversion decay phi->pi0e+e- with the KLOE experiment is presented. A sample of ~9500 signal events was selected from a data set of 1.7 fb^(-1) of e+e- collisions at sqrt(s)~m(phi) collected at the DAFNE e+e- collider. These events were used to obtain the first measurement of the transition form factor |F_{phi,pi^0}(q2)| and a new measurement of the branching ratio of the decay: BR(phi->pi0e+e-)=(1.35+/-0.05+0.05?0.10)×10^(-5). The result improves significantly on previous measurements and is in agreement with theoretical predictions.
Limit on the production of a low-mass vector boson in e+e- ->U, U->e+e- with the KLOE experiment
A. Anastasi, E. Czerwiński, A. Gajos, D. Kamińska, W. Krzemień, P. Moskal, M. Silarski, W. Wiślicki, et al.
abstract
The existence of a new force beyond the Standard Model is compelling because it could explain several striking astrophysical observations which fail standard interpretations. We searched for the light vector mediator of this dark force, the U boson, with the KLOE detector at the DAFNE e+e? collider. Using an integrated luminosity of 1.54 fb^-1, we studied the process e+e->U, with U->e+e-, using radiative-return to search for a resonant peak in the dielectron invariant-mass distribution. We did not find evidence for a signal, and set a 90\%~CL upper limit on the mixing strength between the Standard Model photon and the dark photon, ?^2, at 10^-6--10^-4 in the 5--520~MeV/c2 mass range.
Study of the KS KL -> 3pi0, pi l nu process for Time reversal symmetry test at KLOE-2
A. Gajos on behalf of the KLOE-2 Collaboration
abstract
This work presents prospects for conducting a novel direct test of time-reversal symmetry at the KLOE-2 experiment. Quantum entanglement of neutral K meson pairs uniquely available at KLOE-2 allows to probe directly the time-reversal symmetry (T ) independently of CP violation. This is achieved by a comparison of probabilities for a transition between flavour and CP-definite states and its inverse obtained through exchange of initial and final states. As such, a test requires the reconstruction of the KL ? 3?0 decay accompanied by KS ? ????? with good timing information, a new reconstruction method for this process is also presented which is capable of reconstructing the KL ? 3?0 decay with decay time resolution of O(1?S).
Improved KS Tagging Procedure and Its Impact on Physics at KLOE-2
M. Silarski
abstract
The KLOE experiment at the DA?NE ?-factory performed precise studies of charged and neutral kaon physics, low energy QCD, as well as tests of CP and CPT invariance. For the new run, the KLOE has been upgraded by adding new tagger systems for the ?? physics, the inner tracking chamber and two calorimeters in the final focusing region. We are also improving on kaon identification techniques, in particular algorithms for the KS meson tagging. In this article, we discuss the impact of the improved tagging procedure on studies of the KS decays.
A New Event Display for the KLOE-2 Experiment
W. Krzemień
abstract
In this contribution, we describe KNEDLE ? the new event display for the KLOE-2 experiment. The basic objectives and software requirements are presented. The current status of the development is given along with a short discussion of the future plans.
Ks semileptonic decays and test of CPT symmetry with the KLOE detector
D. Kamińska on behalf of the KLOE-2 Collaboration
abstract
Study of semileptonic decays of neutral kaons allows to perform a test of discrete symmetries, as well as basic principles of the Standard Model. In this paper, a general review on dependency between charge asymmetry constructed for semileptonic decays of short- and long-lived kaons and CPT symmetry is given.
Search for dark Higgsstrahlung in e+ e- -> mu+ mu- and missing energy events with the KLOE experiment
D. Babusci, ..., E. Czerwiński, A. Gajos, D. Kamińska, W. Krzemień, P. Moskal, M. Silarski, W. Wiślicki, et al.
abstract
We searched for evidence of a Higgsstrahlung process in a secluded sector, leading to a final state with a dark photon U and a dark Higgs boson h', with the KLOE detector at DAFNE. We investigated the case of h' lighter than U, with U decaying into a muon pair and h' producing a missing energy signature. We found no evidence of the process and set upper limits to its parameters in the range 2m_mu
Kaon Physics with the KLOE Detector
C. Bloise, E. De Lucia, A. De Santis, P. De Simone, E. Czerwiński, A. Gajos, D. Kamińska, P. Moskal, M. Silarski, A. Di Domenico, A. Passeri, W. Wiślicki
abstract
In this paper, we discuss the recent finalized analyses by the KLOE experiment at DA?NE: the CPT and Lorentz invariance test with entangled K0K0 pairs, and the precision measurement of the branching fraction of the decay K+ ? ?+???+(?). We also present the status of an ongoing analysis aiming to precisely measure the K? mass.
A direct test of T symmetry in the neutral K meson system with KsKl->pi l nu and Kl->3pi0 at the KLOE-2 experiment
A. Gajos on behalf of the KLOE-2 Collaboration
abstract
Quantum entanglement of K and B mesons allows for a direct experimental test
of time-reversal symmetry independent of CP violation. The T symmetry can
be probed by exchange of initial and final states in the reversible transitions be-
tween flavor and CP-definite states of the mesons which are only connected by
the T conjugation. While such a test was successfully performed by the BaBar
experiment with neutral B mesons, the KLOE-2 detector can probe T -violation
in the neutral kaons system by investigating the process with KS->pi l nu
and KL->3pi0 decays. Analysis of the latter is facilitated by a novel recon-
struction method for the vertex of KL->3pi 0 decay which only involves neutral
particles. Details of this new vertex reconstruction technique are presented as
well as prospects for conducting the direct T symmetry test at the KLOE-2
experiment.
Status of measurement of KS -> pi e nu branching ratio and lepton charge asymmetry with the KLOE detector
D. Kamińska on behalf of the KLOE-2 Collaboration
abstract
We present the current status of the analysis of about 1.7 billion K S K L pair
events collected at DAFNE with the KLOE detector to determine the branching
ratio of KS-> pi e nu decay and the lepton charge asymmetry. This sample is
? 4 times larger in statistics than the one used in a previous KLOE analysis,
allowing us to improve the accuracy of the measurement and of the related
tests of CPT symmetry and Delta S = Delta Q rule.
Study of Dalitz decay phi -> eta e+e- with KLOE detector
D. Babusci, ..., I. Balwierz-Pytko, E. Czerwiński, A. Gajos, D. Kamińska, P. Moskal, M. Silarski, W. Wiślicki, et al.
abstract
We have studied the vector to pseudoscalar conversion decay phi -> eta e+e-, with eta -> pi0pi0pi0, with the KLOE detector at DAPHNE. The data set of 1.7 fb-1 of e+e- collisions at sqrt(s)~Mphi contains a clear conversion decay signal of ~31,000 events from which we measured a value of BR(phi -> eta e+e-)=(1.075+-0.007+-0.038)x10-4. The same sample is used to determine the transition form factor by a fit to the e+e- invariant mass spectrum, obtaining b(phi eta) =(1.17 +- 0.10 + 0.07) GeV-2, that improves by a factor of five the precision of the previous measurement and is in good agreement with VMD expectations.
Measurement of the absolute branching ratio of the K+->pi+pi-pi+(gamma) decay with the KLOE detector
KLOE-2 Collaboration: D. Babusci, ..., I. Balwierz-Pytko, E. Czerwiński, A. Gajos, K. Kacprzak, D. Kamińska, P. Moskal, M. Silarski, W. Wiślicki et al.
abstract
The absolute branching ratio of the K+->pi+pi-pi+(gamma)decay, inclusive of final-state
radiation, has been measured using ?17 million tagged K + mesons collected with
the KLOE detector at DAFNE, the Frascati phi-factory. The result is:
BR(K+->pi+pi-pi+(gamma))= 0.05565 +- 0.00031stat +- 0.00025syst
a factor ~5 more precise with respect to the previous result. This work completes
the program of precision measurements of the dominant kaon branching ratios at
KLOE.
Search for light vector boson production in e+e- -> mi+mi- gamma interactions with the KLOE experiment
D. Babusci, I. Balwierz-Pytko, E. Czerwiński, A. Gajos, D. Kamińska, W. Krzemień, P. Moskal, M. Silarski, J. Zdebik, et al.
abstract
We have searched for a light vector boson U, the possible carrier of a dark force, with the KLOE detector at the DAFNE e+e- collider, motivated by the astrophysical evidence for the presence of dark matter in the universe. Using e+e- collisions collected for an integrated luminosity of 239.3~pb?1, we look for a dimuon mass peak in the reaction e+e- -> mu+mu-gamma, corresponding to the decay U->mu+mu-. We find no evidence for a U vector boson signal. We set a 90% CL upper limit for the mixing parameter squared between the photon and the U boson of 1.6×10^5 to 8.6×10^7 for the mass region 520
Test of CPT and Lorentz symmetry in entangled neutral kaons with the KLOE experiment
D. Babusci, ..., I. Balwierz-Pytko, E. Czerwiński, A. Gajos, K. Kacprzak, D. Kamińska, P. Moskal, M. Silarski, W. Wiślicki, J. Zdebik et al.
abstract
Neutral kaon pairs produced in phi decays in anti-symmetric entangled state can be exploited to search for violation of CPT symmetry and Lorentz invariance. We present an analysis of the CP-violating process phi->K_S K_L->pi+pi-pi+pi- based on 1.7 fb-1 of data collected by the KLOE experiment at the Frascati phi-factory DAFNE. The data are used to perform a measurement of the CPT-violating parameters Delta_amu for neutral kaons in the contest of the Standard Model Extension framework. The parameters measured in the reference frame of the fixed stars are: Delta_ao = (-6.0 +- 7.7_{stat} +- 3.1_{syst}) x 10^{-18} GeV Delta_ax = ( 0.9 +- 1.5_{stat} +- 0.6_{syst}) x 10^{-18} GeV Delta_ay = (-2.0 +- 1.5_{stat} +- 0.5_{syst}) x 10^{-18} GeV Delta_az = ( 3.1 +- 1.7_{stat} +- 0.5_{syst}) x 10^{-18} GeV These are presently the most precise measurements in the quark sector of the Standard Model Extension.
GASTONE64: A new front-end ASIC for the cylindrical GEM Inner Tracker of KLOE-2 experiment at DAFNE
A. Balla, E. Czerwiński, et al.
abstract
GASTONE64 (Gem Amplifier Shaper Tracking ON Events) is a novel 64-channel mixed analog-digital ASIC developed to readout the cylindrical GEM inner tracking detector of the KLOE-2 apparatus at the e+e?DA?NEDA?NE collider. It has been designed in the CMOS View the MathML source0.35?m technology and each analog channel is made of preamplifier, shaper and discriminator. The expected input charge ranges between few fC up to 40 fC, the charge sensitivity is 16 mV/fC while the equivalent input noise charge (ENC) is 800 e?+40 e?/pF. The discriminated signals are read-out using a 100 MBit/s LVDS serial data link. The power consumption is about 6 mW/channel.
A new limit on the CP violating decay KS -> 3pi0 with the KLOE experiment
D. Babusci, ..., I. Balwierz-Pytko, E. Czerwiński, P. Moskal, M. Silarski, W. Wiślicki, J. Zdebik et al.
abstract
We have carried out a new direct search for the CP violating decay KS -> 3pi0 with 1.7 fb^-1 of e+e- collisions collected by the KLOE detector at the phi-factory DAFNE. We have searched for this decay in a sample of about 5.9 x 10^8 KS KL events tagging the KS by means of the KL interaction in the calorimeter and requiring six prompt photons. With respect to our previous search, the analysis has been improved by increasing of a factor four the tagged sample and by a more effective background rejection of fake KS tags and spurious clusters. We find no candidates in data and simulated background samples, while we expect 0.12 standard model events. Normalizing to the number of KS -> 2pi0 events in the same sample, we set the upper limit on BR(KS -> 3pi0 < 2.6 x 10^-8 at 90% C.L., five times lower than the previous limit. We also set the upper limit on the eta_000 parameter, |eta_000 | < 0.0088 at 90% C.L., improving by a factor two the latest direct measurement.
Measurement of eta meson production in gamma-gamma interactions and Gamma(eta-->gamma gamma) with the KLOE detector
D. Babusci, ..., I. Balwierz-Pytko, E. Czerwiński, P. Moskal, M. Silarski, W. Wiślicki, J. Zdebik et al.
abstract
We present a measurement of {eta} meson production in photon-photon interactions produced by electron-positron beams colliding with sqrt{s}=1 GeV. The measurement is done with the KLOE detector at the phi-factory DA{Phi}NE with an integrated luminosity of 0.24 fb^{-1}. The e^+e^- --> e^+e^-{eta} cross section is measured without detecting the outgoing electron and positron, selecting the decays {eta}-->{pi}^+{pi}^-{pi}^0 and {eta}-->{pi}^0{pi}^0{pi}^0. The most relevant background is due to e^+e^- --> {eta}{gamma} when the monochromatic photon escapes detection. The cross section for this process is measured as {sigma}(e^+e^- -->{eta}{gamma}) = (856 pm 8_{stat} pm 16_{syst}) pb. The combined result for the e^+e^- -->e^+e^-{eta} cross section is {sigma}(e^+e^- -->e^+e^-{eta}) = (32.72 pm 1.27_{stat} pm 0.70_{syst}) pb. From this we derive the partial width {Gamma}({eta}-->{gamma}{gamma}) = (520 pm 20_{stat} pm 13_{syst}) eV. This is in agreement with the world average and is the most precise measurement to date.
Limit on the production of a light vector gauge boson in phi meson decays with the KLOE detector
D. Babusci, ..., I. Balwierz-Pytko, E. Czerwiński, P. Moskal, M. Silarski, W. Wiślicki, J. Zdebik, et al
abstract
We present a new limit on the production of a light dark-force mediator with the KLOE detector at DAPHNE. This boson, called U, has been searched for in the decay phi -->eta U, with the hypothesis U-->e+e-, analyzing the decay eta-->pi0pi0pi0 in a data sample of 1.7 fb-1 integrated luminosity. This search is combined with a previous result obtained using the decay eta-->pi+pi-pi0, increasing substantially the sensitivity. No structures are observed in the e+e- invariant mass distribution over the background. Combining the two eta decay modes, we set an upper limit at 90% C.L. on the ratio between the U boson coupling constant and the fine structure constant of alpha'/alpha <= 1.5x10^-5 for 30
Precision measurement of sigma(e+e-->pi+pi-gamma)/sigma(e+e-->mu+mu-gamma) and determination of the pi+pi- contribution to the muon anomaly with the KLOE detector
D. Babusci, ..., P. Moskal, E. Czerwiński, I. Balwierz-Pytko, M. Silarski, W. Wiślicki, J. Zdebik et al.
abstract
We have measured the ratio $sigma(e^+e^-
ightarrowpi^+pi^-gamma)/sigma(e^+e^-
ightarrow mu^+mu^-gamma)$, with the KLOE detector at DA$Phi$NE for a total integrated luminosity of $sim$ 240 pb$^{-1}$. From this ratio we obtain the cross section $sigma(e^+e^-
ightarrowpi^+pi^-)$. From the cross section we determine the pion form factor $|F_pi|^2$ and the two-pion contribution to the muon anomaly $a_mu$ for $0.592
Measurement of Gamma(eta->pi^+pi^-gamma)/Gamma(eta->pi^+pi^-pi^0) with the KLOE Detector
D. Babusci, ..., I. Balwierz-Pytko, E. Czerwiński, M. Silarski, P. Moskal, J. Zdebik, et al.
abstract
Measurement of gamma(eta->pi+pi-gamma)/gamma(eta->pi+pi-pi0) with KLOE experiment
D. Babusci, ..., P. Moskal, ..., E. Czerwiński, ..., J. Balwierz, ..., M. Silarski, ..., J. Zdebik et al.
abstract
We report the measurement of the ratio $Gamma(eta o pi^+pi^-gamma)/Gamma(eta o pi^+pi^-pi^0)$ analyzing a large sample of $phi o eta gamma$ decays recorded with the KLOE experiment at the DA$Phi$NE $e^+ e^-$ collider, corresponding to an integrated luminosity of 558 pb$^{-1}$. The $eta o pi^+pi^-gamma$ process is supposed to proceed both via a resonant contribution, mediated by the $
ho$ meson, and a non resonant direct term, connected to the box anomaly. The presence of the direct term affects the partial width value. Our result $R_{eta}=Gamma(eta o pi^+ pi^- gamma)/Gamma(eta o pi^+ pi^- pi^0)= 0.1838pm 0.0005_{stat} pm 0.0030_{syst}$ is in agreement with a recent CLEO measurement, which differs by more 3 $sigma$ from the average of previous results.
Physics topics at KLOE-2
M. Silarski on behalf of the KLOE-2 Collaboration
abstract
The goal of the KLOE?2 experiment operating at the upgraded DAFNE e+e? collider is to collect an integrated luminosity of about 20 fb?1 over 3-4 years of running. The KLOE?2 apparatus is now equipped with an inner tracker, new scintillation calorimeters and tagging detectors for gamma-gamma physics. These will allow measurements to refine and extend the KLOE programme on kaon physics and tests of fundamental symmetries as well as quantum interferometry. Here the latest results from the KLOE data analysis are presented and the perspectives at KLOE-2 outlined.
On the possibility to measure the (pi0 to gamma gamma) decay width and the (gamma* gamma to pi0) transition form factor with the KLOE-2 experiment
D. Babusci, ..., and KLOE-2 Collaboration: F. Archilli, ..., I. Balwierz, E. Czerwiński, P. Moskal, M. Silarski, J. Zdebik et al.
abstract
A possibility of KLOE-2 experiment to measure the width Gamma(pi0 to gamma gamma) and the (pi0 gamma gamma*) form factor F(Q^2) at low invariant masses of the virtual photon in the space-like region is considered. This measurement is an important test of the strong interaction dynamics at low energies. The feasibility is estimated on the basis of a Monte-Carlo simulation. The expected accuracy for Gamma(pi0 to gamma gamma) is at a per cent level, which is better than the current experimental world average and theory. The form factor will be measured for the first time at Q^2 less or equal 0.1 GeV^2 in the space-like region. The impact of these measurements on the accuracy of the pion-exchange contribution to the hadronic light-by-light scattering part of the anomalous magnetic moment of the muon is also discussed.
Revealing Bells nonlocality for unstable systems in high energy physics
B. C. Hiesmayr, A. Di Domenico, C. Curceanu, A. Gabriel, M. Huber, J-A Larsson, P. Moskal
abstract
Entanglement and its consequences?in particular
the violation of Bell inequalities, which defies our concepts
of realism and locality?have been proven to play
key roles in Nature by many experiments for various quantum
systems. Entanglement can also be found in systems
not consisting of ordinary matter and light, i.e. in massive
meson?antimeson systems. Bell inequalities have been discussed
for these systems, but up to date no direct experimental
test to conclusively exclude local realism was found.
This mainly stems from the fact that one only has access to
a restricted class of observables and that these systems are
also decaying. In this Letter we put forward a Bell inequality
for unstable systems which can be tested at accelerator facilities
with current technology. Herewith, the long awaited
proof that such systems at different energy scales can reveal
the sophisticated dynamical nonlocal feature of Nature in
a direct experiment gets feasible. Moreover, the role of entanglement
and CP violation, an asymmetry between matter
and antimatter, is explored, a special feature offered only by
these meson?antimeson systems.
Search for a vector gauge boson in phi meson decays with the KLOE detector
F. Ambrosino, ..., I. Balwierz, E. Czerwiński, P. Moskal, M. Silarski, J. Zdebik et al.
abstract
The existence of a light dark force mediator has been tested with the KLOE detector at DAFNE. This particle, called U, is searched for using the decay chain phi->eta U, eta->pi+pi-pi0, U->e+e-. No evidence is found in 1.5 fb-1 of data. The resulting exclusion plot covers the mass range 5
Observation of the rare eta->e+e-e+e- decay with the KLOE experiment
F. Ambrosino, ..., I. Balwierz, E. Czerwiński, P. Moskal, M. Silarski, J. Zdebik et al.
abstract
We report the first observation of the rare eta->e+e-e+e- decay based on 1.7 fb^{-1} collected by the KLOE experiment at the DAFNE phi-factory. The selection of the e+e-e+e- final state is fully inclusive of radiation. We have identified 362 +- 29 events resulting in a branching ratio of (2.4 +- 0.2_stat+bckg +- 0.1_syst) x 10^{-5}.
gamma gamma physics with the KLOE experiment
F. Archilli, ..., P. Moskal, E. Czerwiński, J. Zdebik, J. Balwierz, M. Silarski et al.
abstract
The processes $e^+e^- o e^+e^-X$, with $X$ being either the $eta$ meson or $pi^0pi^0$, are studied at DA$Phi$NE, with $e^+e^-$ beams colliding at $sqrt{s}simeq1$ GeV, below the $phi$ resonance peak. The data sample is from an integrated luminosity of 240 pb$^{-1}$, collected by the KLOE experiment without tagging of the outgoing $e^+e^-$. Preliminary results are presented on the observation of the $gammagamma oeta$ process, with both $eta opi^+pi^-pi^0$ and $eta opi^0pi^0pi^0$ channels, and the evidence for $gammagamma opi^0pi^0$ production at low $pi^0pi^0$ invariant mass.
Prospects for KLOE-2
P. Moskal for the collaboration KLOE-2
abstract
The basic motivation of the KLOE-2 experiment is the test of fundamental symmetries and Quantum Mechanics coherence of the neutral kaon system, and the search for phenomena beyond the Standard Model in the hadronic and leptonic decays of ground-state mesons. Perspectives for experimentation by means of the KLOE-2 apparatus equipped with the inner tracker, new scintillation calorimeters, and the gamma-gamma taggers at the DA$Phi$NE electron-positron collider upgraded in luminosity and energy are presented.
Proposal for taking data with the KLOE-2 detector at the DAFNE collider upgraded in energy
D. Babusci, ..., P. Moskal, E. Czerwiński, I. Balwierz, M. Silarski, J. Zdebik, et al.
abstract
This document reviews the physics program of the KLOE-2 detector at DA$Phi$NE upgraded in energy and provides a simple solution to run the collider above the $phi$-peak (up to 2, possibly 2.5 GeV). It is shown how a precise measurement of the multihadronic cross section in the energy region up to 2 (possibly 2.5) GeV would have a major impact on the tests of the Standard Model through a precise determination of the anomalous magnetic moment of the muon and the effective fine-structure constant at the $M_Z$ scale. With a luminosity of about $10^{32}$cm$^{-2}$s$^{-1}$, DA$Phi$NE upgraded in energy can perform a scan in the region from 1 to 2.5 GeV in one year by collecting an integrated luminosity of 20 pb$^{-1}$ (corresponding to a few days of data taking) for single point, assuming an energy step of 25 MeV. A few years of data taking in this region would provide important tests of QCD and effective theories by $gammagamma$ physics with open thresholds for pseudo-scalar (like the $eta'$), scalar ($f_0,f'_0$, etc...) and axial-vector ($a_1$, etc...) mesons; vector-mesons spectroscopy and baryon form factors; tests of CVC and searches for exotics. In the final part of the document a technical solution for the energy upgrade of DA$Phi$NE is proposed.
Physics with the KLOE-2 experiment at the upgraded DAFNE
G. Amelino-Camelia, ..., E. Czerwiński, P. Moskal, M. Silarski, J. Zdebik et al.
abstract
Investigation at a $phi$--factory can shed light on several debated issues in particle physics. We discuss: i) recent theoretical development and experimental progress in kaon physics relevant for the Standard Model tests in the flavor sector, ii) the sensitivity we can reach in probing CPT and Quantum Mechanics from time evolution of entangled kaon states, iii) the interest for improving on the present measurements of non-leptonic and radiative decays of kaons and eta/eta$^prime$ mesons, iv) the contribution to understand the nature of light scalar mesons, and v) the opportunity to search for narrow di-lepton resonances suggested by recent models proposing a hidden dark-matter sector. We also report on the $e^+ e^-$ physics in the continuum with the measurements of (multi)hadronic cross sections and the study of gamma gamma processes.
Technical Design Report of the Inner Tracker for the KLOE-2 experiment
F. Archilli, ..., E. Czerwiński, J. Balwierz, P. Moskal, M. Silarski, J. Zdebik, et al.
abstract
The technical design report of the Inner Tracker for the KLOE-2 experiment is presented
Test of T, CP, and CPT Discrete Symmetries via Kaons' Transitions at KLOE-2
S. Gamrat
abstract
Pairs of neutral kaons produced at the DAFNE collider allowed to perform the first model-independent direct test of T, CP, and CPT symmetries utilizing the oscillations between the flavor and CP eigenbases. The analysis of 1.7fb^-1 data collected in 2004?2005 in the KLOE experiment led to the determination of ratios and double ratios of kaons? decay rates, establishing a few percent precision of the measurement in a model-free manner.
Latest Results in Kaon Physics on the KLOE Data and Status of Analysis of the KLOE-2 Data
E. Czerwiński
abstract
The KLOE-2 Collaboration concluded its data-taking at the DA?NE phi-factory of the Laboratori Nazionali di Frascati of INFN, collecting 5.5 fb-1 of data at the center of mass energy corresponding to the mass of the phi(1020). This sample together with the 2.5 fb-1 collected by the KLOE Collaboration until 2006 constitutes the largest sample in the world collected at the peak of the phi resonance. With the kaons produced in the decay phi->KSKL it is possible to perform very precise tests of the discrete symmetries T, CP, and CPT, and moreover the entanglement of the neutral kaons can be exploited to perform unique tests of quantum mechanics. Also large samples of eta mesons are produced in phi radiative decays, allowing to study the rare decays of this meson. KLOE-2 has also installed two tagging devices for electrons and positrons scattered in gg processes, with the main goal to study the single pi0 production. The search of new vector bosons in the hidden dark sector is also performed with the KLOE/KLOE-2 data. An information about the latest results with KLOE data on CPT test with charge asymmetry of KS semileptonic decays and a preliminary result on the CPT test in transitions is given.
Near threshold kaon-kaon interaction in the reactions e+e-->K+K-gamma and e+e-->K0bar{K0}gamma
L. Leśniak, F. Sobczuk, M. Silarski and F. Morawski
abstract
Strong interactions between pairs of the K+K- and K0bar{K0} mesons can be studied in radiative decays of phi(1020) mesons. We present a theoretical model of the reactions e+e-->K+K-gamma and e+e-->K0bar{K0}gamma. The K+K- and K0bar{K0} effective mass dependence of the differential cross sectionsis derived. The total cross sections and the branching fractions for the two radiative phi decays are calculated.
Discrete symmetries studies at KLOE-2
D. Kisielewska
abstract
The KLOE and KLOE-2 experiments at the Laboratori Nazionali di Frascati (Italy) collected almost 8 fb ?1 of integrated luminosity at the energy equal to the mass of ? meson. The excellent time resolution of the electromagnetic calorimeter and the very good accuracy on both momentum and vertex reconstruction of the tracking system allow to study discrete symmetries to
the utmost precision as well as light meson spectroscopy, dark forces searches, hadronic cross-section measurements and studies of ??-physics. CPT symmetry test with the lepton charge asymmetry measured in K S semileptonic decays with 1.7 fb ?1 of KLOE data, tests of time reversal and CPT in transitions in ? ? K S K L ? ?e?, 3? 0 (2? 0 ) decays with newly acquired data with the KLOE-2 detector will be presented and discussed.
CP, T and CPT tests with neutral kaons at KLOE-2
M. Silarski
abstract
We report on the recent results on CP, T and CPT tests in the neutral kaon sector obtained with the KLOE dataset. Search for the CP-violating decay KS?3?0 is described. We present also recent measurement of the charge asymmetry for the KS??e? decay and preliminary results of direct test of T and CPT in neutral kaon transitions. Prospects of further improvement of these tests with KLOE-2 dataset are also given.
Latest studies on the reaction e+ e- --> K + K- gamma
L. Leśniak, M. Silarski
abstract
Recent theoretical studies of the e+ e- -> K + K- gamma process are described. Three main reaction mechanisms are considered: the initial state radiation, the final state radiation and the strong interaction between the outgoing K+ K- mesons. The K+ K- effective mass distributions are derived for three different models which in past have been used for a description of the e+ e- -> pi+ pi- gamma data. Also the numerical results for the angular photon and kaon distributions are presented. A new model of the e+ e- -> M_1 M_2 gamma reactions is outlined which can serve for multichannel analyses of the radiative processes with a production of two pseudoscalar mesons M_1 and M_2.
Discrete symmetries and QM studies with entangled neutral kaons at KLOE-2
A. Gajos
abstract
The long history of kaon physics results produced by KLOE is being continued at the upgraded KLOE-2 detector. Entangled neutral kaon pairs produced at DA?NE are a unique tool to probe discrete symmetries and QM basic principles at the utmost precision. The status of the newest ongoing analyses using the most refined analysis tools will be presented and discussed:(i) search for decoherence and CPT violation effects in the ? ? K(S)K(L) ? ? (+) ? (?) ? (+) ? (?) decay,(ii) test of CP and CPT symmetries in K(S) semileptonic decays,(iii) test of time reversal and CPT in transitions in ? ? K(S)K(L) ? ?e?, 3? (0), 2? decays,(iv) study of the K(S) ? ? (+) ? (?) ? (0) decay.
Latest discrete symmetries and Quantum Mechanics studies with KLOE-2
D. Kamińska
abstract
The KLOE-2 experiment at the INFN Laboratori Nazionali di Frascati (LNF) is currently taking data at the upgraded e (+) e? DAFNE collider, representing the continuation of KLOE with a new physics program including kaon interferometry and test of discrete symmetries among the main topics. In fact entangled neutral kaon pairs produced at DAFNE are a unique tool to probe discrete symmetries and/or QM basic principles at the utmost precision. The status of the latest ongoing analyses on KLOE data using the most refined analyses tools will be presented and discussed including prospects for KLOE-2: (i) search for decoherence and CPT violation effects in the ? ? K(S)K(L) ? ? (+) ? (?) ? (+) ? (?) decay, (ii) test of CP and CPT symmetries in K(s) semileptonic decays, (iii) test of Time reversal and CPT in transitions in ? ? K(S)K(L) ? ?e?, 3? (0) (2? (0)) decays, (iv) study of the K(S) ? ? (+) ? (?) ? (0) decay.
Search for dark forces with KLOE
A. Gajos for the KLOE and KLOE-2 Collaborations
abstract
During the last years several Dark Sector Models have been proposed in order to address striking astrophysical observations which failed standard interpretations. In the minimal case a new vector particle, the so called dark photon, or A' or U boson, is introduced, with small coupling with Standard Model particles. Also, the existence of a dark Higgs boson h' is postulated, in analogy with the Standard Model, to give mass to the U boson through the Spontaneous Symmetry Breaking mechanism. The KLOE experiment working at DAFNE, an e+e- collider operating in Frascati (near Rome), searched for the existence of the U boson investigating three different processes and six different final states: (1) in Dalitz decays of the phi meson phi->eta U, with U -> e+e- and U -> pi+pi-pi0 and pi0pi0pi0, (2) in e+e- -> Ug events, with U decaying into lepton and pion pairs, (3) in the dark Higgsstrahlung process, e+e- -> Uh', U -> mu+mu-, h' invisible. Limits on the model parameters have been set at 90 % CL for U boson masses below 1 GeV. Further improvements are expected in terms of sensitivity and discovery potential with the new KLOE-2 detector.
Theoretical studies of the reaction e+e- ->K+K-gamma
L. Leśniak, M. Silarski
abstract
We present studies of the e+e- -> K+K-gamma reaction for the e+e- center-of-mass energies close to the phi(1020) meson mass. Different mechanisms leading to the final state are considered. The strong interaction amplitudes of the K+K- pairs in the S - wave are taken into account. In addition, the photon emission in the initial state, the final state radiation effects and all the possible interference terms are included in the transition matrix elements. The K+K- effective mass distributions and the angular dependence of the reaction cross-section are calculated.
The KLOE-2 experiment at DAFNE
M. Silarski
abstract
The KLOE-2 experiment at the INFN Laboratori Nazionali di Frascati (LNF) is currently taking data at the upgraded e+e- DAFNE collider. Present Run II follows a development phase to assess the feasibility of a long term acquisition program, Run I, which successfully ended in July 2015 with 1 fb-1 integrated luminosity collected in less than eight months. KLOE-2 represents the continuation of the KLOE experiment with a new physics program. The KLOE detector has undergone several upgrades including state-of-the-art cylindrical GEM Inner Tracker, electron-positron taggers for the gammagamma-physics studies and new calorimeters around the interaction point. In this article we briefly present the overview of the KLOE-2 experiment including the present status and achievements together with the physics plans.
Recent KLOE results on kaon physics
E. Czerwiński on behalf of the KLOE-2 Collaboration
abstract
A short review of two measurements recently published by KLOE/KLOE-2 collaborations is presented. Namely the most stringent limits of the CPT-violating parameters Delta a_mu for neutral kaons, and the absolute branching ratio of K+->pi+pi-pi+(gamma) decay. In addition a discussion of starting KLOE-2 project is performed.
Study of KS semileptonic decays and CPT test with the KLOE detector
D. Kamińska on behalf of the KLOE-2 collaboration
abstract
Study of semileptonic decays of neutral kaons allows to perform a test of discrete symmetries, as well as basic principles of the Standard Model. In this paper a general review on dependency between charge asymmetry constructed for semileptonic decays of short- and long-lived kaons and CPT symmetry is given. The current status of determination of charge asymmetry for short-lived kaon, obtained by reconstruction of about 10^5 KS->pen decays collected at DAFNE with the KLOE detector is also reviewed
A direct test of T symmetry in the neutral K meson system at KLOE-2
Aleksander Gajos (on behalf of theKLOE-2 Collaboration)
abstract
This work presents prospects for conducting a novel direct test of time-reversal symmetry at the KLOE-2 experiment. Quantum entanglement of neutral K meson pairs uniquely available at KLOE-2 allows to probe the T symmetry directly and independently of CP violation. This is achieved by a comparison of probabilities for a transition and its inverse obtained through an exchange of initial and final states. Such transitions between flavor and CP-definite states of the neutral kaons are only connected by the T conjugation which ensures the CP-independence of the test. While a similar measurement was performed by the BaBar experiment with neutral B mesons, the KLOE-2 detector can test T-violation in the neutral kaons system. Such a test requires i.a. reconstruction of the KL -> 3pi0 decay accompanied by Ks -> pienu with good timing information. Therefore a new reconstruction method for the KL -> 3pi0 decay is also presented which is capable of reconstructing this process with decay time resolution of O(1 tauS).
A direct test of time-reversal symmetry in the neutral K meson system with KS -> pi e nu and KL -> 3pi0 at KLOE-2
A. Gajos on behalf of the KLOE-2 Collaboration
abstract
Quantum entanglement of K and B mesons allows for a direct experimental test of time-reversal symmetry independent of CP violation. The T symmetry can be probed by exchange of initial and final states in the reversible transitions between flavor and CP- definite states of the mesons which are only connected by the T conjugation. While such a test was successfully performed by the BaBar experiment with neutral B mesons, the KLOE-2 detector can probe T -violation in the neutral kaons system by investigating the process with KS ? ??l??l and KL ? 3?0 decays. Analysis of the latter is facilitated by a novel reconstruction method for the vertex of KL ? 3?0 decay which only involves neutral particles. Details of this new vertex reconstruction technique are presented as well as prospects for conducting the direct T symmetry test at the KLOE-2 experiment.
Status of the measurement of KS -> nev branching ratio and lepton charge asymmetry with the KLOE detector
D. Kamińska on behalf of the KLOE-2 collaboration
abstract
We present the current status of the analysis of about 1.7 billion KS KL pair events collected at DA?NE with the KLOE detector to determine the branching ratio of KS ? ?e? decay and the lepton charge asymmetry. This sample is ? 4 times larger in statistics than the one used in the previous most precise result, from KLOE as well, allowing us to improve the accuracy on the measurement and related tests of CPT symmetry and ?S = ?Q rule.
Status of KS -> pi e nu branching ratio and lepton charge asymmetry measurements with the KLOE detector
D. Kamińska for KLOE-2 Collaboration
abstract
Study of the KSKl->pi l nu 3pi0 process for a direct test of T symmetry at KLOE-2
A. Gajos for the KLOE-2 Collaboration
abstract
Quantum Mechanics and CPT Tests with Neutral Kaons at the KLOE Experiment
I. Balwierz-Pytko
abstract
Neutral kaons produced in the correlated pairs at the DA?NE ?-factory offer unique possibilities to perform fundamental tests of CPT invariance, as well as of the basic principles of quantum mechanics. The analysis of the data collected by the KLOE experiment allows to improve results on several parameters describing CPT violation and decoherence, and to measure the regeneration cross section on the beam pipe materials.
Development of CGEM Technology for Ultra-light Tracking Detectors: the KLOE-2 Inner Tracker
A. Balla, G. Bencivenni, P. Branchini, A. Budano, M. Capodiferro, S. Cerioni, P. Ciambrone, E. Czerwiński, et al.
abstract
KLOE-2 at the ?-factory DA?NE of INFN Laboratori Nazionali di Frascati (LNF), is the first experiment using the GEM technology with a cylindrical geometry (CGEM), developed at the LNF by the Inner Tracker group and within the RD51 Collaboration. Four layers with 26÷41 cm diameters and L = 70 cm, each realized as a Triple-GEM detector, compose this new detector. To produce GEM foils of unprecedented size, the novel single-mask manufacturing procedure has been developed with the TE-MPE-EM CERN group, together with the realization of a novel XV readout pattern. The adopted solutions allowed the total material budget to be kept below 2% of the radiation length X0. The final assembly of the Inner Tracker has been completed on March 14, 2014. The production procedure will be reported together with the validation test results.
Status and perspectives of the KLOE-2 experiment
F. Achilli, ..., I. Balwierz, E. Czerwiński, P. Moskal, M. Silarski, J. Zdebik et al.
abstract
The KLOE experiment has acquired an integrated luminosity greater than 2.5 fb?1 at the peak of ?-resonance on the e+e? DA?NE collider in the Frascati National Laboratory (LNF). New data taking with the upgraded detector (KLOE-2) and DA?NE should start in the end of 2011. Main modifications of the detector and new interaction region give a unique possibility to collect about 20 fb?1 in 3 years. The KLOE-2 wide scientific program which contains the experimental study of CP and CPT symmetries, quantum decoherence, ?? physics and search of the dark matter is presented and briefly discussed.
Recent results on hadron physics at KLOE
D. Babusci, ..., I. Balwierz - Pytko, E. Czerwiński, A. Gajos, K. Kacprzak, P. Moskal, M. Silarski, W. Wiślicki, J. Zdebik et al.
abstract
One of the basic motivations of the KLOE and KLOE-2 collaborations is the test of fundamental symmetries and the search for phenomena beyond the Standard Model via the hadronic and leptonic decays of ground-state mesons and via their production in the fusion of virtual gamma quanta exchanged between colliding electrons and positrons. This contribution includes brief description of results of recent analysis of the KLOE data aimed at (i) the search for the dark matter boson, (ii) determination of the hadronic and light-by-light contributions to the g-2 muon anomaly and (iii) tests of QCD anomalies.
Search for the Ks-->3pi0 decay with the KLOE detector
M. Silarski
abstract
The Ks-->3pi0 decay is a pure CP violating process which, assuming CPT invariance, allows one to investigate direct CP violation. This decay has not been observed so far, and the best upper limit on the branching ratio BR(Ks-->3pi0) < 1.2 x 10-7 is two orders of magnitude larger than predictions based on the Standard Model. In this article we present the search for the Ks-->3pi0 decay performed with the KLOE detection system operating at the DAFNE phi-factory at the Frascati Laboratory of the Italian Institute of Nuclear Physics. We describe the experimental techniques used in the background rejection and signal events selection as well as the evaluation of almost five times lower upper limit on the Ks-->3pi0 branching ratio. We discuss shortly also the perspectives for a new measurement using the KLOE-2 apparatus equipped with a new inner tracker and the calorimeters at low theta angle.
Recent results on CP and CPT tests at KLOE/KLOE-2
A. Di Domenico, M. Silarski, on behalf of the KLOE-2 collaboration
abstract
Nuclear Physics B Proc. Suppl. 233 (2012) 73
Neutral kaon pairs produced in phi decays offer a unique possibility to perform fundamental tests of discrete symmetries. Among the most recent results obtained by the KLOE experiment at DAFNE, the Frascati phi-factory, there is the new best limit on the branching ratio of the CP-violating decay Ks --> 3pi0, BR < 2.6 x 10^?8
at 90% C.L..The search for possible violations of the CPT symmetry and Lorentz invariance in the context of the Standard-Model Extension (SME) is also described; the new analysis approach fully exploits quantum interferometry in phi --> KsKl -->pi+pi?, pi+pi? decays. Finally the status and perspectives of the new data taking campaign with the KLOE-2 experiment at the upgraded DAFNE machine are briefly reviewed.
KLOE results in kaon physics and prospects for KLOE-2
E. Czerwiński for the KLOE Collaboration
abstract
The phi-factory DAPHNE offers a possibility to select pure kaon beams, charged and neutral ones. In particular, neutral kaons from phi->KS KL are produced in pairs and the detection of a KS (KL) tags the presence of a KL (KS). This allows to perform precise measurements of kaon properties by means of KLOE detector. Another advantage of a phi-factory consists in fact that the neutral kaon pairs are produced in a pure quantum state (J^(PC) = 1^(--)), which allowsto investigate CP and CPT symmetries via quantum interference effects, as well as the basic principles of quantum mechanics.A review of the most recent results of the KLOE experiment at DAPHNE using pure kaon beams or via quantum interferometry is presented together with prospects for kaon physics at KLOE-2.
Neutral kaon interferometry at KLOE and KLOE-2
I. Balwierz
abstract
Neutral kaons produced in correlated pairs at a phi-factory offer unique possibilities to perform fundamental tests of CPT invariance, as well as of the basic principles of quantum mechanics. The analysis of the data collected by the KLOE experiment at DAFNE is still ongoing with the aim of improving previous results and limits on several parameters describing CPT violation and decoherence. Ancillary measurements like the regeneration cross section on the beam pipe materials are also in progress and will be very useful to reduce the systematic uncertainties. Prospects on improvements at the KLOE-2 experiment, aiming at an increase of the integrated luminosity of about a factor of ten with an upgraded detector, will be also discussed.
U boson searches at KLOE
F. Archilli, ..., I. Balwierz, .., E. Czerwiński, ..., P. Moskal, ..., M. Silarski, ..., W. Wiślicki, ..., J. Zdebik, et al.
abstract
The existence of a secluded gauge sector could explain several puzzling astrophysical observations. This hypothesis can be tested at low energy e+e- colliders such as DAPHNE. Preliminary results obtained with KLOE data and perpectives for the KLOE-2 run, where a larger data sample is expected, are discussed.
Study of the decoherence of entangled kaons by the interaction with thermal photons
I. Balwierz, W. Wiślicki, P. Moskal
abstract
The KLOE-2 detector is a powerful tool to study the temporal evolution of quantum entangled pairs of kaons. The accuracy of such studies may in principle be limited by the interaction of neutral kaons with thermal photons present inside the detector. Therefore, it is crucial to estimate the probability of this effect and its influence on the interference patterns. In this paper we introduce the phenomenology of the interaction of photons with neutral kaons and present and discuss the obtained quantitative results.
Hadron physics with KLOE-2
E. Czerwiński, ..., I. Balwierz, P. Moskal, M. Silarski, J. Zdebik et al
abstract
In the upcoming month the KLOE-2 data taking campaign will start at the upgraded DAFNE phi-factory of INFN Laboratori Nazionali di Frascati. The main goal is to collect an integrated luminosity of about 20 fb (-1) in 3-4 years in order to refine and extend the KLOE program on both kaon physics and hadron spectroscopy. Here the expected improvements on the results of hadron spectroscopy are presented and briefly discussed.
A direct test of time-reversal symmetry in the neutral K meson system with Ks->pilv and Kl->3pi0 at KLOE-2
Aleksander Gajos
A novel neutral vertex reconstruction algorithm for regeneration events in the KsKl -> pi+pi-pi0pi0 channel
Aleksander Gajos
presented at: MesonnNet 2013
Studies of the neutral kaon regeneration with the KLOE detector
Izabela Pytko
presented at: MesonNet meeting 2013
Studies of the neutral kaon regeneration with the KLOE detector
I. Balwierz
presented at: School on Amplitude Analysis in Modern Physics
Search for the Ks-->3pi0 decay with the KLOE detector
M. Silarski
presented at: School on Amplitude Analysis in Modern Physics from hadron spectroscopy to CP phases, Bad Honnef, Germany
