We present a measurement of the K–π vector current form-factor parameters for the decay KL→π±e∓ν. We use 328 pb−1 of data collected in 2001 and 2002, corresponding to ∼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 IKe needed to measure the CKM matrix element |Vus| for KL→π±e∓ν decays. Our result is λ+=(28.6±0.5±0.4)×10−3 for a linear fit, and λ+′=(25.5±1.5±1.0)×10−3, λ+″=(1.4±0.7±0.4)×10−3 for a quadratic fit.
Using 1.6 fb−1 of e + e − → ϕ → ηγ data collected with the KLOE detector at DAΦNE, the Dalitz plot distribution for the η → π + π − π 0 decay is studied with the world’s largest sample of ∼ 4.7 · 106 ...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 gX 2 Y term. The statistical uncertainty of all parameters is improved by a factor two with respect to earlier measurements.
We measured, with the KLOE detector, the spectrum of π+π− invariant mass in a sample of 6.7×105e+e−→π+π−γ events with the photon at large polar angle (θγ>45°) at a centre of mass energy s around the ...ϕ mass. We observe in this spectrum a clear contribution from the intermediate process ϕ→ f0(980)γ. A sizeable effect is also observed in the distribution of the pion forward–backward asymmetry. We use different theoretical models to fit the spectrum and we determine the f0 mass and coupling constants to the ϕ, to π+π− and to KK¯.
We have measured the fully inclusive K+→μ+ν(γ) absolute branching ratio with the KLOE experiment at DAΦNE, the Frascati ϕ-factory. From some 865 283 K+→μ+ν(γ) decays obtained from a sample of ...∼5.2×108, ϕ-meson decays, we find BR(K+→μ+νμ(γ))=0.6366±0.0009stat.±0.0015syst., corresponding to an overall fractional error of 0.27%. Using recent lattice results on the decay constants of pseudoscalar mesons one can obtain an estimate for the CKM mixing matrix element |Vus|=0.2223±0.0026.
Test of a small prototype of the KLOE drift chamber in magnetic field Avanzini, C; Ciapetti, G; Lucia, E.De ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2000, Letnik:
449, Številka:
1
Journal Article
Recenzirano
We report on a beam test of a small prototype of the KLOE drift chamber in magnetic field. The chamber was operated with a 90% He–10% iC
4H
10 gas mixture. Drift space–time relations were studied. ...The average spatial resolution is about
110
μm
in the absence of magnetic field and
120
μm
in a
0.6
T
magnetic field. Measurements of the primary ionization and drift velocity are reported. The measurement of d
E/d
x in a He-based gas mixture is also discussed.
Using a large sample of pure, slow, short lived
K
0
mesons collected with KLOE detector at DAΦNE, we have measured the
K
S
lifetime. From a fit to the proper time distribution we find
τ
(
K
S
...)=(89.562±0.029
stat
±0.043
syst
) ps. This is the most precise measurement to date of the short lived
K
0
meson lifetime, in good agreement with the world average derived from previous measurements. We observe no dependence of the lifetime on the direction of the
K
S
in galactic coordinates.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).We present a measurement of eta meson production in photon-photon interactions produced by electron-positron beams ...colliding with ... GeV. The measurement is done with the KLOE detector at the -factory DA Phi NE with an integrated luminosity of 0.24 fb super(-1). The e super(+) e super(-) arrow right e super(+) e super(-) eta cross section is measured without detecting the out-going electron and positron, selecting the decays eta arrow right pi super(+) pi super(-) pi super(0) and eta arrow right pi super(0) pi super(0) pi super(0). The most relevant background is due to e super(+) e super(-) arrow right eta gamma when the monochromatic photon escapes detection. The cross section for this process is measured as sigma (e super(+) e super(-) arrow right eta gamma ) = (856 plus or minus 8 sub(stat) plus or minus 16 sub(syst)) pb. The combined result for the e super(+) e super(-) arrow right e super(+) e super(-) eta cross section is sigma (e super(+) e super(-) arrow right e super(+) e super(-) eta ) = (32.72 plus or minus 1.27 sub(stat) plus or minus 0.70 sub(syst)) pb. From this we derive the partial width Gamma ( eta arrow right gamma gamma ) = (520 plus or minus 20 sub(stat) plus or minus 13 sub(syst)) eV. This is in agreement with the world average and is the most precise measurement to date.
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 DA Phi NE. 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) < m(U) < 1000 MeV, m(h') < m(U). (C) 2015 The Authors. Published by Elsevier B.V.
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 DA Phi NE e(+)e(-) collider. Using an integrated luminosity of 1.54 fb(-1), we studied the process e(+)e(-) -> U gamma, 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, epsilon(2), at 10(-6)-10(-4) in the 5-520 MeV/c(2) mass range.
PDF
