Diploma thesis
Measurement of the neutral kaon regeneration cross-section in beryllium at P=110 MeV/c with the KLOE detector
Supervisor: prof. Paweł Moskal
abstract The main result of this thesis is determination of the neutral kaon regeneration cross-section in beryllium for momentum of p_K=110 MeV/c. It was obtained by analyzing data for K_L->K_S regeneration in the cylindrical beam pipe of the KLOE detector. The corresponding cross-sections for the KLOE drift chamber inner wall and the spherical beam pipe were also evaluated as well as values for aluminium and carbon. The K_L mesons were produced in the center of the detector in the collision region of e^+ and e^- beams of the DAFNE collider that worked at the phi meson resonance peak. The analysis was based on identification of regenerated events e^+ e^- -> phi -> K_S K_L -> pi^+ pi^- K_S^reg -> pi^+ pi^- pi^+ pi^- and their extraction from the distributions of the vertex position of the K_L meson decays into pi^+ pi^-. The regeneration cross-sections were determined based on the extracted number of regenerated events and number of the K_L mesons passing through the regenerator. Obtained results are equal to: sigma_reg^Be=(50.0 +/- 0.7^stat +/- 5.0^syst)mbarn for beryllium, sigma_reg^BP=(77.6 +/- 0.3^stat +/- 7.8^syst)mbarn for the beam pipe, sigma_reg^DC=(75.7 +/- 0.3^stat +/- 7.6^syst)mbarn for the drift chamber inner wall, sigma_reg^Al=(170 +/- 3^stat +/- 38^syst)mbarn for aluminium and sigma_reg^C=(61 +/- 1^stat +/- 11^syst)mbarn for carbon.
Publications
ARTICLES CONFERENCE PROCEEDINGS POSTERS
- Study of Dalitz decay phi -> eta e+e- with KLOE detectorD. Babusci, ..., I. Balwierz-Pytko, E. Czerwiński, A. Gajos, D. Kamińska, P. Moskal, M. Silarski, W. Wiślicki, et al.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 detectorKLOE-2 Collaboration: D. Babusci, ..., I. Balwierz-Pytko, E. Czerwiński, A. Gajos, K. Kacprzak, D. Kamińska, P. Moskal, M. Silarski, W. Wiślicki et al.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 experimentD. Babusci, I. Balwierz-Pytko, E. Czerwiński, A. Gajos, D. Kamińska, W. Krzemień, P. Moskal, M. Silarski, J. Zdebik, et al.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 520Test of CPT and Lorentz symmetry in entangled neutral kaons with the KLOE experimentD. Babusci, ..., I. Balwierz-Pytko, E. Czerwiński, A. Gajos, K. Kacprzak, D. Kamińska, P. Moskal, M. Silarski, W. Wiślicki, J. Zdebik et al.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.A new limit on the CP violating decay KS -> 3pi0 with the KLOE experimentD. Babusci, ..., I. Balwierz-Pytko, E. Czerwiński, P. Moskal, M. Silarski, W. Wiślicki, J. Zdebik et al.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 detectorD. Babusci, ..., I. Balwierz-Pytko, E. Czerwiński, P. Moskal, M. Silarski, W. Wiślicki, J. Zdebik et al.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 detectorD. Babusci, ..., I. Balwierz-Pytko, E. Czerwiński, P. Moskal, M. Silarski, W. Wiślicki, J. Zdebik, et alWe 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 30Precision 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 detectorD. Babusci, ..., P. Moskal, E. Czerwiński, I. Balwierz-Pytko, M. Silarski, W. Wiślicki, J. Zdebik et al.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 $0.592Measurement of Gamma(eta->pi^+pi^-gamma)/Gamma(eta->pi^+pi^-pi^0) with the KLOE DetectorD. Babusci, ..., I. Balwierz-Pytko, E. Czerwiński, M. Silarski, P. Moskal, J. Zdebik, et al.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 experimentD. Babusci, ..., and KLOE-2 Collaboration: F. Archilli, ..., I. Balwierz, E. Czerwiński, P. Moskal, M. Silarski, J. Zdebik et al.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.Search for a vector gauge boson in phi meson decays with the KLOE detectorF. Ambrosino, ..., I. Balwierz, E. Czerwiński, P. Moskal, M. Silarski, J. Zdebik et al.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 5Observation of the rare eta->e+e-e+e- decay with the KLOE experimentF. Ambrosino, ..., I. Balwierz, E. Czerwiński, P. Moskal, M. Silarski, J. Zdebik et al.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}.Proposal for taking data with the KLOE-2 detector at the DAFNE collider upgraded in energyD. Babusci, ..., P. Moskal, E. Czerwiński, I. Balwierz, M. Silarski, J. Zdebik, et al.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.
- Quantum Mechanics and CPT Tests with Neutral Kaons at the KLOE ExperimentI. Balwierz-Pytkopublished in: Acta Phys. Polon. B Suppl. 6 (2013) 1101-1105Neutral 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.
- Status and perspectives of the KLOE-2 experimentF. Achilli, ..., I. Balwierz, E. Czerwiński, P. Moskal, M. Silarski, J. Zdebik et al.published in: Particle Physics at the Tercentenary of Mikhail Lomonosov: pp. 324-327.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 KLOED. Babusci, ..., I. Balwierz - Pytko, E. Czerwiński, A. Gajos, K. Kacprzak, P. Moskal, M. Silarski, W. Wiślicki, J. Zdebik et al.published in: 2013 : QCD and High Energy Interactions : proceedings of the XLVIIIth Rencontres de Moriond La Thuile, Aosta Valley, Italy-MarchOne 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.
- Neutral kaon interferometry at KLOE and KLOE-2I. Balwierzpublished in: PoS STORI11 (2011) 054Neutral 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 KLOEF. Archilli, ..., I. Balwierz, .., E. Czerwiński, ..., P. Moskal, ..., M. Silarski, ..., W. Wiślicki, ..., J. Zdebik, et al.published in: J. Phys. Conf. Ser. 335 (2011) 012067The 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 photonsI. Balwierz, W. Wiślicki, P. Moskalpublished in: Frascati Physics Series LI (2010) 37-42The 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-2E. Czerwiński, ..., I. Balwierz, P. Moskal, M. Silarski, J. Zdebik et alpublished in: Nucl. Phys. Proc. Suppl. 207-208:137-140 (2010)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.
- Studies of the neutral kaon regeneration with the KLOE detectorI. BalwierzSchool on Amplitude Analysis in Modern Physics
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