5,360 research outputs found
The BTeV Experiment
BTeV is an approved forward collider experiment at the Fermilab Tevatron
dedicated to precision studies of CP violation, mixing, and rare decays of
beauty and charmed hadrons. The BTeV detector has been designed to achieve
these goals. Pixel detectors cover the interaction region and vertex
computation is included in the lowest level trigger.Comment: Presented at EPS 2003 HEP conference in Aachen, German
Mesons spectroscopy in Gaussian Sum Rules
The masses of the mesons are investigated from a view-point of
ordinary light-heavy system in the framework of the Gaussian sum rules, which
are worked out by means of the Laplacian transformation to the usual Borel sum
rules. Using the standard input of QCD non-perturbative parameters, the
corresponding mass spectra and couplings of the currents to the
mesons are obtained. Our results are GeV
and GeV, which are in accordance well with
the experimental data, 1.969 GeV and 2.317 GeV.Comment: 5 pages, 4 figure
A High Statistics Measurement of the Lambdac+ Lifetime
A high statistics measurement of the Lambdac+ lifetime from the Fermilab
fixed-target FOCUS photoproduction experiment is presented. We describe the
analysis technique with particular attention to the determination of the
systematic uncertainty. The measured value of 204.6 +/- 3.4 (stat.) +/- 2.5
(syst.) fs from 8034 +/- 122 Lambdac -> pKpi decays represents a significant
improvement over the present world average.Comment: Submitted to Physical Review Letter
A Measurement of the Ds+ Lifetime
A high statistics measurement of the Ds+ lifetime from the Fermilab
fixed-target FOCUS photoproduction experiment is presented. We describe the
analysis of the two decay modes, Ds+ -> phi(1020)pi+ and Ds+ ->
\bar{K}*(892)0K+, used for the measurement. The measured lifetime is 507.4 +/-
5.5 (stat.) +/- 5.1 (syst.) fs using 8961 +/- 105 Ds+ -> phi(1020)pi+ and 4680
+/- 90 Ds+ -> \bar{K}*(892)0K+ decays. This is a significant improvement over
the present world average.Comment: 5 pages, 3 figures, 2 tables, submitted to PR
Search for CP Violation in the decays D+ -> K_S pi+ and D+ -> K_S K+
A high statistics sample of photo-produced charm from the FOCUS(E831)
experiment at Fermilab has been used to search for direct CP violation in the
decays D+->K_S pi+ and D+ -> K_S K+. We have measured the following asymmetry
parameters relative to D+->K-pi+pi+: A_CP(K_S pi+) = (-1.6 +/- 1.5 +/- 0.9)%,
A_CP(K_S K+) = (+6.9 +/- 6.0 +/- 1.5)% and A_CP(K_S K+) = (+7.1 +/- 6.1 +/-
1.2)% relative to D+->K_S pi+. The first errors quoted are statistical and the
second are systematic. We also measure the relative branching ratios:
\Gamma(D+->\bar{K0}pi+)/\Gamma(D+->K-pi+pi+) = (30.60 +/- 0.46 +/- 0.32)%,
\Gamma(D+->\bar{K0}K+)/\Gamma(D+->K-pi+pi+) = (6.04 +/- 0.35 +/- 0.30)% and
\Gamma(D+->\bar{K0}K+)/\Gamma(D+->\bar{K0}pi+) = (19.96 +/- 1.19 +/- 0.96)%.Comment: 4 pages, 3 figure
A measurement of branching ratios of and hadronic decays to four-body final states containing a
We have studied hadronic four-body decays of and mesons with a
in the final state using data recorded during the 1996-1997 fixed-target
run at Fermilab high energy photoproduction experiment FOCUS. We report a new
branching ratio measurement of . We make the first observation
of three new decay modes with branching ratios ,
\Gamma(D^+\to\K_S K^+ K^-\pi^+)/\Gamma(D^+\to K_S
\pi^+\pi^+\pi^-)=0.0077\pm0.0015\pm0.0009, and , where
in each case the first error is statistical and the second error is systematic.Comment: 4 pages, 1 table, 2 figures, submitted to Physical Review Letter
New FOCUS results on charm mixing and CP violation
We present a summary of recent results on CP violation and mixing in the
charm quark sector based on a high statistics sample collected by
photoproduction experiment FOCUS (E831 at Fermilab). We have measured the
difference in lifetimes for the decays: and . This translates into a measurement of the mixing parameter in
the \d0d0 system, under the assumptions that is an equal mixture of
CP odd and CP even eigenstates, and CP violation is negligible in the neutral
charm meson system. We verified the latter assumption by searching for a CP
violating asymmetry in the Cabibbo suppressed decay modes , and . We show preliminary
results on a measurement of the branching ratio .Comment: 9 pages, 6 figures, requires espcrc2.sty. Presented by S.Bianco at
CPConf2000, September 2000, Ferrara (Italy). In this revision, fixed several
stylistic flaws, add two significant references, fixed a typo in Tab.
Study of Hadronic Five-Body Decays of Charmed Mesons
We study the decay of D+ and Ds+ mesons into charged five body final states,
and report the discovery of the decay mode D+ -> K+K-Pi+Pi+Pi-, as well as
measurements of the decay modes D+ -> K-Pi+Pi+Pi+Pi-, Ds+ -> K+K-Pi+Pi+Pi-, Ds+
-> PhiPi+Pi+Pi- and D+/Ds+ -> Pi+Pi+Pi+Pi-Pi-. An analysis of the resonant
substructure is also included, with evidence suggesting that both decays
proceed primarily through an a1 vector resonance.Comment: 11 pages, 3 figure
Observation of a 1750 MeV/c^2 Enhancement in the Diffractive Photoproduction of K^+K^-
Using the FOCUS spectrometer with photon beam energies between 20 and 160
\gev, we confirm the existence of a diffractively photoproduced enhancement in
at 1750 \mevcc with nearly 100 times the statistics of previous
experiments. Assuming this enhancement to be a single resonance with a
Breit-Wigner mass shape, we determine its mass to be
\mevcc and its width to be \mevcc. We find no
corresponding enhancement at 1750 \mevcc in , and again neglecting any
possible interference effects we place limits on the ratio . Our results are consistent with previous
photoproduction experiments, but, because of the much greater statistics,
challenge the common interpretation of this enhancement as the
seen in annihilation experiments.Comment: 10 pages, 5 figure
Charm System Tests of CPT and Lorentz Invariance with FOCUS
We have performed a search for CPT violation in neutral charm meson
oscillations. While flavor mixing in the charm sector is predicted to be small
by the Standard Model, it is still possible to investigate CPT violation
through a study of the proper time dependence of a CPT asymmetry in right-sign
decay rates for and \d0b\to K^+\pi^-. This asymmetry is
related to the CPT violating complex parameter and the mixing parameters
and : . Our 95% confidence
level limit is . Within the
framework of the Standard Model Extension incorporating general CPT violation,
we also find 95% confidence level limits for the expressions involving
coefficients of Lorentz violation of GeV, GeV, and GeV,
where is the factor which incorporates mixing parameters ,
and the doubly Cabibbo suppressed to Cabibbo favored relative strong phase
.Comment: 12 pages 5 figure
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