941 research outputs found
PHENIX Highlights
Recent highlights of measurements by the PHENIX experiment at RHIC are
presented.Comment: 8 pages, 9 figures. Talk at Quark Matter 200
Search for decays to invisible final states at Belle
We report the result from the first search for decays to invisible
final states. The analysis is performed on a data sample of 924
collected at and near the and resonances with the
Belle detector at the KEKB asymmetric-energy collider. The
absolute branching fraction is determined using an inclusive sample,
obtained by fully reconstructing the rest of the particle system including the
other charmed particle. No significant signal yield is observed and an upper
limit of is set on the branching fraction of to
invisible final states at 90\% confidence level.Comment: 17 pages, 4 figures, submitted to PRD(RC
Energy scan of the cross sections and evidence for decays into charged bottomonium-like states
Using data collected with the Belle detector at the KEKB asymmetric-energy
collider, we measure the energy dependence of the cross sections from thresholds up to GeV.
We find clear and peaks with little or no
continuum contribution. We study the resonant substructure of the
transitions and find evidence that they
proceed entirely via the intermediate isovector states and
. The relative fraction of these states is loosely constrained by
the current data: the hypothesis that only is produced is excluded
at the level of 3.3 standard deviations, while the hypothesis that only
is produced is not excluded at a significant level.Comment: 8 pages, 4 figures, submitted to Physical Review Letter
Study of Excited States Decaying into and Baryons
Using a data sample of 980 of annihilation data
taken with the Belle detector operating at the KEKB asymmetric-energy
collider, we report the results of a study of excited states that
decay, via the emission of photons and/or charged pions, into or
ground state charmed-strange baryons. We present new measurements of
the masses of all members of the , ,
, , and isodoublets, measurements of
the intrinsic widths of those that decay strongly, and evidence of previously
unknown transitions.Comment: Submitted to PR
Studies of charmed strange baryons in the final state at Belle
We report the discovery of , observed by its decay into
the final state , and present the first observation and evidence
of the decays of and into .
We also perform a combined analysis of the with the
and decay modes to measure
the ratios of branching fractions, masses and widths with improved accuracy. We
measure the ratios of branching fractions , , and , where the uncertainties are
statistical and systematic. The analysis is performed using a 980 fb
data sample collected with the Belle detector at the KEKB asymmetric-energy
collider.Comment: Submitted to PR
Measurement of the Branching Fraction of the Decay in Fully Reconstructed Events at Belle
We present an analysis of the exclusive
decay, where represents an
electron or a muon, with the assumption of charge-conjugation symmetry and
lepton universality. The analysis uses the full data sample
collected by the Belle detector, corresponding to 711 fb of integrated
luminosity. We select the events by fully reconstructing one meson in
hadronic decay modes, subsequently determining the properties of the other
meson. We extract the signal yields using a binned maximum-likelihood fit to
the missing-mass squared distribution in bins of the invariant mass of the two
pions or the momentum transfer squared. We measure a total branching fraction
of , where the
uncertainties are statistical and systematic, respectively. This result is the
first reported measurement of this decay.Comment: 23 pages, 19 figure
Observation of an alternative candidate in
We perform a full amplitude analysis of the process , where refers to either or . A new
charmoniumlike state that decays to is observed with a
significance of . Its mass is ()
MeV/ and width is () MeV. The
hypothesis is favored over the hypothesis at the level
of . The analysis is based on the 980 data sample
collected by the Belle detector at the asymmetric-energy collider
KEKB.Comment: 17 pages, 11 figure
Measurement of the CKM Matrix Element from at Belle
We present a new measurement of the CKM matrix element from decays, reconstructed with the full Belle data set
of integrated luminosity. Two form factor
parameterizations, originally conceived by the Caprini-Lellouch-Neubert (CLN)
and the Boyd, Grinstein and Lebed (BGL) groups, are used to extract the product
and the decay form factors, where
is the normalization factor and is a small
electroweak correction. In the CLN parameterization we find
, , , . For the BGL parameterization we
obtain , which is consistent with the World Average when correcting for
. The branching fraction of is measured to be . We also present a new
test of lepton flavor universality violation in semileptonic decays,
. The errors correspond to the statistical and
systematic uncertainties respectively. This is the most precise measurement of
and form factors to date and the first
experimental study of the BGL form factor parameterization in an experimental
measurement
Deuteron and antideuteron production in Au+Au collisions at sqrt(s_NN)=200 GeV
The production of deuterons and antideuterons in the transverse momentum
range 1.1 < p_T < 4.3 GeV/c at mid-rapidity in Au + Au collisions at
sqrt(s_NN)=200 GeV has been studied by the PHENIX experiment at RHIC. A
coalescence analysis comparing the deuteron and antideuteron spectra with those
of protons and antiprotons, has been performed. The coalescence probability is
equal for both deuterons and antideuterons and increases as a function of p_T,
which is consistent with an expanding collision zone. Comparing (anti)proton
yields p_bar/p = 0.73 +/- 0.01, with (anti)deuteron yields: d_bar/d = 0.47 +/-
0.03, we estimate that n_bar/n = 0.64 +/- 0.04.Comment: 326 authors, 6 pages text, 5 figures, 1 Table. Submitted to PRL.
Plain text data tables for the points plotted in figures for this and
previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
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