2,677 research outputs found
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
The first level muon trigger in the central toroid of the ATLAS experiment
We present the design of the first level muon trigger in the central toroid of the ATLAS experiment at the Large Hadron Collider (LHC). A trigger is foreseen based on fast, finely segmented gaseous detectors, Resistive Plate Chambers (RPC), to unambiguously identify the interaction bunch crossing. We describe the detectors and the logic scheme of the trigger. © 1995
A Study of the Radiative Ke3 Decay and Search for Direct Photon Emission with the KLOE Detector
We present a measurement of the ratio R =
\Gamma(\keg;\Estar>30\mev,\qstar>20^\circ)\Gamma(\kegf) of data corresponding to about 3.5
million Ke3(g) events and about 9000 radiative events. Our result is R=(924 +/-
23(stat) +/-16(syst)10^{-5} for the branching ratio and X=-2.3 +/- 1.3(stat)
+/- 1.4(syst) for the parameter describing direct emission.Comment: 8 pages, 7 figure
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.
Study of the process e+e- -> omega pi0 in the phi-meson mass region with the KLOE detector
We have studied the e+e- -> omegapi0 cross section in the sqrt(s) interval
1000-1030 MeV using the pi+pi-pi0pi0 and pi0pi0gamma final states with a sample
of ~600 pb^-1 collected with the KLOE detector at DAFNE. By fitting the
observed interference pattern around M_phi for both final states, we extract
the ratio of the decay widths Gamma(omega->pi0gamma)/Gamma(omega->pi+pi-pi0) =
0.0897 +- 0.0016 and derive the branching fractions BR(omega -> pi+pi-pi0)=
(90.24 +- 0.19)%, BR(omega -> pi0gamma) = (8.09 +- 0.14)%. The parameters
describing the e+e- -> omegapi0 reaction around M_\phi are also used to extract
the branching fraction for the OZI and G-parity violating phi -> omegapi0
decay: BR(phi->omegapi0) = (4.4 +- 0.6)x10^-5.Comment: 12 Pages, 4 figures, submitted to Physics Letter
Search for the K_S -> e+e- decay with the KLOE detector
We present the result of a direct search for the decay K_S -> e+e-, obtained
with a sample of e+e- -> phi -> K_S K_L events produced at DAFNE, the Frascati
phi-factory, for an integrated luminosity of 1.9 fb^-1. The search has been
performed using a pure K_S beam tagged by the simultaneous detection of a K_L
interaction in the calorimeter. Background rejection has been optimized by
using both kinematic and particle identification cuts. We find BR(K_S -> e+e-)
< 9x10^-9 at 90% CL, which improves by an order of magnitude on the previous
best limit.Comment: 13 pages, 11 figures, submitted to Physics Letters
Determination of Dalitz plot slopes and asymmetries with the KLOE detector
We have studied, with the KLOE detector at the DANE -Factory, the
dynamics of the decay using mesons from the
decay for an integrated luminosity = 450
pb. From a fit to the Dalitz plot density distribution we obtain a
precise measurement of the slope parameters. An alternative parametrization
relates the slopes to that for showing the
consistency of KLOE results for both channels. We also obtain the best
confirmation of the -invariance in the decay.Comment: 15 pages, 7 figure
Precision measurement of and determination of the contribution to the muon anomaly with the KLOE detector
We have measured the ratio
, with the KLOE detector at DANE for a total integrated
luminosity of 240 pb. From this ratio we obtain the cross section
. From the cross section we determine the
pion form factor and the two-pion contribution to the muon anomaly
for GeV, = . This result confirms the
current discrepancy between the Standard Model calculation and the experimental
measurement of the muon anomaly.Comment: 18 pages, 8 figures, minor text corrections, one table added, version
to appear on Physics Letters
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
- …