arXiv subjects

KLOE collaboration

Publications and source records attributed to KLOE collaboration.

14 recordsLinked to original sources

arXiv2008

Study of the process e+e- -> omega p0 with the KLOE detector

Using ~600 pb-1 collected with the KLOE detector at DAPhiNE, we have studied the production cross section of pi+ pi- pi0 pi0 and p0p0 gamma final states in e+e- collisions at center of mass energies between 1000 and 1030 MeV. By fitting the observed interference pattern around Mphi for both final states, we extract a measurement (preliminary) for the ratio Gamma(omega -> pi0 gamma)/Gamma(omega -> pi+ pi- pi0) = 0.0934 +- 0.0022. Since these two final states represent the 98% of the omega decay channels, we use unitarity to derive BR(omega -> pi+pi-pi0)= (89.94 +- 0.23)% and BR(omega -> pi0 gamma) = (8.40 +- 0.19)%. Moreover, the parameters describing the e+e- -> pi+ pi- pi0 pi0 reaction around Mphi are used to extract the branching fraction for the OZI and G-parity violating phi -> omega pi0 decay: BR(phi -> omega pi0) = (5.63 +- 0.70) x 10^-5.

hep-ex↗

arXiv2008

Recent results from KLOE experiment

We report the newest results from the KLOE experiment on hadronic physics, such as the parameters of scalars f0 and a0, the eta meson mass measurements and dynamics, the first observation of the eta -> p+p-e+e- rare decay, and study of e+e- -> omega p0 cross section around the phi resonance.

hep-ph↗

arXiv2007

Search for phi to K0 K0bar gamma decay with KLOE

The KLOE collaboration has searched for the phi to K0 K0bar gamma decay using a sample of 1.4 fb-1 of e+e- collisions at W ~ M(phi) collected with the KLOE experiment at the Frascati e+e- collider DAFNE. No previous search exists for this decay, while many theory models predict a BR of 10-8 for this channel. We set a preliminary value of the U.L. on this BR to 1.8x10-8 at 90% C.L.. This limit rules out most of the existing theory predictions.

hep-ex↗

arXiv2007

Measurement of the slope parameter αfor the η\to 3π^0 decay at KLOE

We report a preliminary measurement of the slope parameter $α$ for the $η\to 3\piz$ decay carried out with KLOE at DA$Φ$NE; where $α$ is the parameter describing the energy dependence of the square of the matrix element for this decay. By fitting the event density in the Dalitz plot with a collected statistic of 420 pb$^{-1}$ we determine $α= -0.027 \pm 0.004 (stat) ^{+0.004}_{-0.006} (syst)$. This result is consistent with current chiral perturbation theory calculations within the unitary approach.

hep-ex↗

arXiv2007

Determination of the η\toπ^+π^-π^0 Dalitz Plot slopes and asymmetries with the KLOE detector

We have studied, with the KLOE detector at the DA$Φ$NE $Φ$-Factory, the dynamics of the decay $η\toπ^+π^-π^0$ using data from the radiative $ϕ\toηγ$ decay for an integrated luminosity $L = 450 \textrm{pb^{-1}}$. From a fit to the Dalitz plot density distribution we obtain a precise measurement of the slope parameters. This should allow to improve the knowledge of the decay amplitude which is sensitive to the u-d quark mass difference. We also present new best results on the C-violating asymmetries in the $η\toπ^+π^-π^0$ decay.

hep-ex↗

arXiv2006

First observation of quantum interference in the process phi -> KS KL ->pi+pi-pi+pi-: a test of quantum mechanics and CPT symmetry

We present the first observation of quantum interference in the process phi -> KS KL ->pi+pi-pi+pi-. This analysis is based on data collected with the KLOE detector at the e^+e^- collider DAFNE in 2001--2002 for an integrated luminosity of about 380pb^-1. Fits to the distribution of Delta t, the difference between the two kaon decay times, allow tests of the validity of quantum mechanics and CPT symmetry. No deviations from the expectations of quantum mechanics and CPT symmetry have been observed. New or improved limits on various decoherence and CPT violation parameters have been obtained

hep-ex↗

arXiv2006

Measurement of the Pion Formfactor with KLOE and Study of the Reaction f0(980) to pi+pi-

At the Frascati phi-factory DAPHNE the pion formfactor is measured by means of the 'radiative return', i.e. by using events in which one of the collider electrons (positrons) has radiated an initial state radiation photon, lowering in such a way the invariant mass M_pipi of the two-pion-system. In a recent publication of the KLOE collaboration the initial state radiation photon had been required to be at small polar angles with respect to the beam axis. We are presenting results from a new and complementary analysis in which the photon is tagged at large polar angles. Only like this the threshold region M_pipi^2<0.35 GeV^2 becomes accessible. Moreover, the final state pi+pi-gamma allows to study the phi radiative decay into the scalar particle f_0(980) with f_0(980) \to pi+pi-. For the first time the two-pion mass spectrum could be fitted with different theoretical models for the description of this phi radiative decay.

hep-ex↗

arXiv2006

Measurement of the Branching Ratio of the KL -> pi+pi- decay with the KLOE Detector

We present a measurement of the branching ratio of the CP violating decay KL->pi+pi- performed by the KLOE experiment at the phi factory DAFNE. We use 328 pb-1 of data collected in 2001 and 2002, corresponding to ~ 150 million tagged KL mesons. We find BR(KL->pi+pi-) = $(1.963 +/- 0.012 +/- 0.017)x 10^-3. This branching ratio measurement is fully inclusive of final-state radiation. Using the above result, we determine the modulus of the amplitude ratio |η_{+-}| to be (2.219 +/- 0.013)x 10^{-3} and |ε| to be (2.216 +/- 0.013)x 10^{-3}.

hep-ex↗

arXiv2006

Study of the decay phi--> f0(980)g --> pi+pi-g with the KLOE detector

We measured, with the KLOE detector, the spectrum of pi+pi- invariant mass in a sample of 6.7 x 10^5 e+e- --> pi+pi-g events with the photon at large polar angle (theta_g>45^o) at a centre of mass energy sqrt(s) around the phi mass. We observe a clear contribution from the intermediate process phi --> f0(980)g. A sizeable effect is also observed in the distribution of the forward-backeard asymmetry. We use different theoretical models to fit the spectrum and we determine the f_0 mass and coupling constants to the phi, to pi+pi- and to KK.

hep-ex↗

arXiv2006

Measurement of the Form-Factor Slopes for the Decay KLe3 with the KLOE Detector

We present a measurement of the K-pi vector current form-factor parameters for the Ke3 decay. We use 328 pb$^{-1}$ of data collected in 2001 and 2002, corresponding to about 2 million Ke3 events. Measurements of semileptonic form factors provide information about the dynamics of the strong interaction and are necessary for evaluation of the phase-space integral Ie_K needed to measure the CKM matrix element Vus for Ke3 decays. Our result is $l=(28.6\pm0.5\pm0.4)10^{-3}$ for a linear fit, and $l'=(25.5\pm1.5\pm1.0)10^{-3}$, $l''=(1.4\pm0.7\pm0.4)10^{-3}$ for a quadratic fit.

hep-ex↗

arXiv2005

Upper limit on the eta -> pi+pi- branching ratio with the KLOE experiment

We have searched with the KLOE detector for the P and CP violating decay eta -> pi^+pi^- in a sample of 1.55 x 10^7 eta's from the decay phi -> eta gamma of phi mesons produced in e+e- annihilations at DAFNE. No signal is found. We obtain the upper limit BR(eta -> pi^+pi^-) < 1.3 x 10^-5 at 90% confidence level.

hep-ex↗

arXiv2003

Kaon Interferometry at KLOE: Present and Future

Interferometry with neutral kaons at KLOE is reviewed. The preliminary results on phi->KS KL->pi+pi- pi+pi- and decoherence parameter are presented. The impact of C-even background and regenerators is shortly discussed and updated. Finally KLOE perspectives on interferometry at DAPHNE and expectations at a new higher luminosity phi-factory are briefly illustrated.

hep-ex↗

arXiv2003

Measurement of the hadronic cross section at DAPHNE with the KLOE detector

We have measured the cross section sigma(e+e- \to pi+pi-gamma) as a function of the pi+pi- invariant mass, M_pipi, with the KLOE detector at DAPHNE (W=m_phi=1.02GeV). The photon in the above process is due to Initial State Radiation. Dividing by a theoretical radiator function we obtain the cross section sigma(e+e- \to pi+pi-) for the mass range 0.37<M_pipi^2<0.93GeV^2. We extract the pion form factor and the hadronic contribution to the muon anomaly, a_mu.

hep-ex↗

arXiv2002

KLOE recent results

Since april 1999, the KLOE experiment at DAFNE has collected about 200 inverse pb of data, produced in electron-positron collision at the c.m. energy of 1020 MeV, the mass of the phi meson. These data have been used for detailed studies on the phi radiative decays, as well as on rare K short decays. The first results, based on the 20 inverse pb collected in year 2000 are presented here

hep-ex↗