2,255 research outputs found
A Simple Explanation for the X(3872) Mass Shift Observed for Decay to D^{*0} {D^0}bar
We propose a simple explanation for the increase of approximately
3 MeV/c^2 in the mass value of the X(3872) obtained from
D^{*0} {D^0}bar decay relative to that obtained from decay to J/psi pi+ pi-.
If the total width of the X(3872) is 2-3 MeV, the peak position in the
D^{*0} {D^0}bar invariant mass distribution is sensitive to the final state
orbital angular momentum because of the proximity of the X(3872) to D^{*0}
{D^0}bar threshold. We show that for total width 3 MeV and one unit of orbital
angular momentum, a mass shift ~3 MeV/c^2 is obtained; experimental mass
resolution should slightly increase this value. A consequence is that
spin-parity 2^- is favored for the X(3872).Comment: 3.5 pages, 4 eps figure
Chiral Suppression of Scalar Glueball Decay
Because glueballs are SU(3)_{Flavor} singlets, they are expected to couple
equally to u,d, and s quarks, so that equal coupling strengths to \pi^+\pi^-
and K^+K^- are predicted. However, we show that chiral symmetry implies the
scalar glueball amplitude for G_0 \to \qbq is proportional to the quark mass,
so that mixing with \sbs mesons is enhanced and decays to K^+K^- are favored
over \pi^+\pi^-. Together with evidence from lattice calculations and from
experiment, this supports the hypothesis that f_0(1710) is the ground state
scalar glueball.Comment: 9 pages; This revision reconciles posting (approximately) with
published version. Posting contains figures that are omitted in the
publicatio
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The status of strange meson spectroscopy
The present status of strange meson spectroscopy is reviewed with emphasis on the results obtained with the LASS spectrometer at SLAC. The systematics of the level structure are discussed with respect to quark model expectations, and the impact of the proposed KAON Factory on the future of the subject considered. 12 refs., 14 figs
Renaissance of the ~1 TeV Fixed-Target Program
This document describes the physics potential of a new fixed-target program
based on a ~1 TeV proton source. Two proton sources are potentially available
in the future: the existing Tevatron at Fermilab, which can provide 800 GeV
protons for fixed-target physics, and a possible upgrade to the SPS at CERN,
called SPS+, which would produce 1 TeV protons on target. In this paper we use
an example Tevatron fixed-target program to illustrate the high discovery
potential possible in the charm and neutrino sectors. We highlight examples
which are either unique to the program or difficult to accomplish at other
venues.Comment: 31 pages, 11 figure
The BES f_0(1810): a new glueball candidate
We analyze the f_0(1810) state recently observed by the BES collaboration via
radiative J/\psi decay to a resonant \phi\omega spectrum and confront it with
DM2 data and glueball theory. The DM2 group only measured \omega\omega decays
and reported a pseudoscalar but no scalar resonance in this mass region. A
rescattering mechanism from the open flavored KKbar decay channel is considered
to explain why the resonance is only seen in the flavor asymmetric \omega\phi
branch along with a discussion of positive C parity charmonia decays to
strengthen the case for preferred open flavor glueball decays. We also
calculate the total glueball decay width to be roughly 100 MeV, in agreement
with the narrow, newly found f_0, and smaller than the expected estimate of
200-400 MeV. We conclude that this discovered scalar hadron is a solid glueball
candidate and deserves further experimental investigation, especially in the
K-Kbar channel. Finally we comment on other, but less likely, possible
assignments for this state.Comment: 11 pages, 4 figures. Major substantive additions, including an
ab-initio, QCD-based computation of the glueball inclusive decay width,
evaluation of final state effects, and enhanced discussion of several
alternative possibilities. Our conclusions are unchanged: the BES f_0(1810)
is a promising glueball candidat
A partial wave analysis of the centrally produced K+K- and K0K0 systems in pp interactions at 450 GeV/c and new information on the spin of the fJ(1710)
A partial wave analysis of the centrally produced K+K- and K0K0 channels has
been performed in pp collisions using an incident beam momentum of 450 GeV/c.
An unambiguous physical solution has been found in each channel. The striking
feature is the observation of peaks in the S-wave corresponding to the f0(1500)
and fJ(1710) with J = 0. The D-wave shows evidence for the f2(1270)/a2(1320),
the f2(1525) and the f2(2150) but there is no evidence for a statistically
significant contribution in the D-wave in the 1.7 GeV mass region.Comment: 15 pages, Latex, 5 Figure
Study of the P-wave charmonium state \chi_{cJ} in \psi(2S) decays
The processes , and have been studied using a sample of produced
decays. We determine the total width of the to be
MeV. We present the first
measurement of the branching fraction , where the first error is statistical and the
second one systematic. Branching fractions of and
are also reported.Comment: 10 pages, revtex, 3 figures, 2 table
Measurement of the Inclusive Charm Cross Section at 4.03 GeV and 4.14 GeV
The cross section for charmed meson production at and 4.14
GeV has been measured with the Beijing Spectrometer. The measurement was made
using 22.3 of data collected at 4.03 GeV and 1.5
of data collected at 4.14 GeV. Inclusive observed cross sections for
the production of charged and neutral D mesons and momentum spectra are
presented. Observed cross sections were radiatively corrected to obtain tree
level cross sections. Measurements of the total hadronic cross section are
obtained from the charmed meson cross section and an extrapolation of results
from below the charm threshold.Comment: 11 pages, 13 figures. The top level tex file is paper.tex. It builds
the paper from other tex files in this .tar and the .eps file
Measurement of decays to baryon pairs
A sample of 3.95M decays registered in the BES detector are used
to study final states containing pairs of octet and decuplet baryons. We report
branching fractions for , ,
, ,
, ,
, and . These results
are compared to expectations based on the SU(3)-flavor symmetry, factorization,
and perturbative QCD.Comment: 22 pages, 21 figures, 4 table
Measurement of the Total Cross Section for Hadronic Production by e+e- Annihilation at Energies between 2.6-5 Gev
Using the upgraded Beijing Spectrometer (BESII), we have measured the total
cross section for annihilation into hadronic final states at
center-of-mass energies of 2.6, 3.2, 3.4, 3.55, 4.6 and 5.0 GeV. Values of ,
, are determined.Comment: Submitted to Phys. Rev. Let
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