2,525 research outputs found
Calibration Strategy and Efficiency measurement of the Muon Identification procedure at LHCb
We present a strategy for calibrating with data the LHCb muon identification procedure and for extracting in-situ the performance. Two main calibration samples are used: the inclusive decay as a source of muons and the decay as a source of hadrons decaying and non-decaying in flight. For each of them we describe the selection, the expected purity and the rates for different running scenarios. The distributions extracted from calibration samples are compared with those obtained from a generic b-inclusive sample. An estimate of the precision that can be reached in the evaluation of the muon identification efficiency and misidentification rate is given as a function of the collected statistics
Precision tests of the Standard Model with leptonic and semileptonic kaon decays
We present a global analysis of leptonic and semileptonic kaon decays data,
including all recent results by BNL-E865, KLOE, KTeV, ISTRA+, and NA48.
Experimental results are critically reviewed and combined, taking into account
theoretical (both analytical and numerical) constraints on the semileptonic
kaon form factors. This analysis leads to a very accurate determination of Vus
and allows us to perform several stringent tests of the Standard Model
A global fit to determine the pseudoscalar mixing angle and the gluonium content of the eta' meson
We update the values of the eta-eta' mixing angle and of the eta' gluonium
content by fitting our measurement R_phi = BR(phi to eta' gamma)/ BR(phi to eta
gamma) together with several vector meson radiative decays to pseudoscalars (V
to P gamma), pseudoscalar mesons radiative decays to vectors (P to V gamma) and
the eta' to gamma gamma, pi^0 to gamma gamma widths. From the fit we extract a
gluonium fraction of Z^2_G = 0.12 +- 0.04, the pseudoscalar mixing angle psi_P
= (40.4 +- 0.6) degree and the phi-omega mixing angle psi_V = (3.32 +- 0.09)
degree. Z^2_G and psi_P are fairly consistent with those previously published.
We also evaluate the impact on the eta' gluonium content determination of
future experimental improvements of the eta' branching ratios and decay width.Comment: 13 pages, 7 figures to submit to JHE
Study of the a_0(980) meson via the radiative decay phi->eta pi^0 gamma with the KLOE detector
We have studied the phi->a_0(980) gamma process with the KLOE detector at the
Frascati phi-factory DAPhNE by detecting the phi->eta pi^0 gamma decays in the
final states with eta->gamma gamma and eta->pi^+ pi^- pi^0. We have measured
the branching ratios for both final states: Br(phi->eta pi^0 gamma)=(7.01 +/-
0.10 +/- 0.20)x10^-5 and (7.12 +/- 0.13 +/- 0.22)x10^-5 respectively. We have
also extracted the a_0(980) mass and its couplings to eta pi^0, K^+ K^-, and to
the phi meson from the fit of the eta pi^0 invariant mass distributions using
different phenomenological models.Comment: 17 pages, 6 figures, submitted to Physics Letters B. Corrected typos
in eq.
Charged kaon lifetime at KLOE
Preliminary result on the charged kaon lifetime, obtained by the KLOE
experiment operating at DANE, the Frascati -factory, is presentedComment: 3 pages, 3 figures, to appear in the proceedings of 42nd Rencontres
de Moriond on Electroweak Interactions and Unified Theories, La Thuile, Aosta
Valley, Italy, 10-17 Mar 200
Precision Measurement of KS Meson Lifetime with the KLOE detector
Using a large sample of pure, slow, short lived K0 mesons collected with KLOE
detector at DaFne, we have measured the KS lifetime. From a fit to the proper
time distribution we find tau = (89.562 +- 0.029_stat +- 0.043_syst) ps. This
is the most precise measurement today in good agreement with the world average
derived from previous measurements. We observe no dependence of the lifetime on
the direction of the Ks.Comment: 5 pages, 7 figure
Determination of CP and CPT violation parameters in the neutral kaon system using the Bell-Steinberger relation and data from the KLOE experiment
We present an improved determination of the CP and CPT violation parameters
Re(epsilon) and Im(delta) based on the unitarity condition (Bell-Steinberger
relation) and on recent results from the KLOE experiment. We find Re(epsilon) =
(159.6 \pm 1.3)10^-5 and Im(delta) = (0.4 \pm 2.1)10^-5, consistent with no CPT
violation.Comment: Submitted to JHE
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