1,843 research outputs found
Production of , , and in hadronic decays
A coherent study of the production of (, 2, 3 corresponding to
, , and ) in is
reported based on a previously proposed glueball and nonet mixing
scheme, and a factorization for the decay of , where
denotes the isoscalar vector mesons and , and denotes
pseudoscalar mesons. The results show that the decays are very
sensitive to the structure of those scalar mesons, and suggest a glueball in
the GeV region, in line with Lattice QCD. The presence of significant
glueball mixings in the scalar wavefunctions produces peculiar patterns in the
branching ratios for , which are in good agreement
with the recently published experimental data from the BES collaboration.Comment: Version accepted by PRD; Numerical results in Tab IV and VI changed
due to correction of an error in quoting an experimental datum; Conclusion is
not change
Multichannel calculation for Ds* vector states and the Ds(2632) resonance
We study bound states below threshold and resonances above threshold in the
D0-K+ and Ds-eta systems, using a many-coupled-channel model for non-exotic
meson-meson scattering applied to states with the quantum numbers of c-sbar
quark-antiquark vector mesons. We fit the ground state at 2.112 GeV, whence the
lowest resonances in D0-K+ come out at 2.61, 2.72, 3.03, and 3.08 GeV. The
resonance at 2.61 GeV acquires a width of about 8 MeV, while its partial P-wave
cross section is up to six times larger in Ds-eta than in D0-K+, provided a
mechanism accounting for Okubo-Zweig-Iizuka--forbidden decays is included. The
latter finding is in agreement with the observations of the SELEX collaboration
with respect to the recently reported DsJ(2632) resonance. Therefore, we
conclude that the DsJ(2632) is most probably the first recurrence excitation of
the Ds*(2112) meson.Comment: 11 pages, 6 figures; v2: Significant improvements for threshold
behavior, and for the hadronic widths by including additional two-meson
channels. Misprints in formulas correcte
Rapid Thermalization by Baryon Injection in Gauge/Gravity Duality
Using the AdS/CFT correspondence for strongly coupled gauge theories, we
calculate thermalization of mesons caused by a time-dependent change of a
baryon number chemical potential. On the gravity side, the thermalization
corresponds to a horizon formation on the probe flavor brane in the AdS throat.
Since heavy ion collisions are locally approximated by a sudden change of the
baryon number chemical potential, we discuss implication of our results to RHIC
and LHC experiments, to find a rough estimate of rather rapid thermalization
time-scale t_{th} < 1 [fm/c]. We also discuss universality of our analysis
against varying gauge theories.Comment: 9 pages, 7 figures. v2: minor clarifications, version to appear in
PR
Intrinsic Low Temperature Paramagnetism in B-DNA
We present experimental study of magnetization in -DNA in
conjunction with structural measurements. The results show the surprising
interplay between the molecular structures and their magnetic property. In the
B-DNA state, -DNA exhibits paramagnetic behaviour below 20 K that is
non-linear in applied magnetic field whereas in the A-DNA state, remains
diamagnetic down to 2 K. We propose orbital paramagnetism as the origin of the
observed phenomena and discuss its relation to the existence of long range
coherent transport in B-DNA at low temperature.Comment: 5 pages, 4 figures, submitted to Physical Review Letters October 200
Consistent analysis of the reaction and
The production of mesons in the reactions and
is described consistently within a relativistic meson exchange
model of hadronic interactions. The photoproduction can be described quite well
over the entire energy range of available data by considering an and a
resonance, in addition to the -channel mesonic current. The
observed angular distribution is due to the interference between the
-channel and the nucleon resonance - and -channel contributions. Our
analysis yields positions close to 1650 MeV and 1870 MeV for the and
resonances, respectively. We argue that, at present, identifying these
states with the known resonance and the missing
resonance predicted at 1880 MeV, respectively, would be premature. It is found
that the nucleonic current is relatively small and that the
coupling constant cannot be much larger than . As for the
reaction, different current contributions are
constrained by a combined analysis of this and the photoproduction reaction.
Difficulties to simultaneously account for the 47-MeV and 144-MeV angular
distributions measured by the COSY-11 and DISTO collaborations, respectively,
are addressed.Comment: minor revision, scheduled to a appear in Phys. Rev. C 69 (May 2004),
revtex, 17 pages, 10 figures, 3 table
Glueball enhancements in p(gamma,VV)p through vector meson dominance
Double vector meson photoproduction, p(gamma, G -> VV)p, mediated by a scalar
glueball G is investigated. Using vector meson dominance (VMD) and
Regge/pomeron phenomenology, a measureable glueball enhancement is predicted in
the invariant VV = rho rho and omega omega mass spectra. The scalar glueball is
assumed to be the lightest physical state on the daughter pomeron trajectory
governing diffractive vector meson photoproduction. In addition to cross
sections, calculations for hadronic and electromagnetic glueball decays, G -> V
V' (V,V'= rho, omega, phi, gamma), and gamma_v V -> G transition form factors
are presented based upon flavor universality, VMD and phenomenological
couplings from phi photoproduction analyses. The predicted glueball decay
widths are similar to an independent theoretical study. A novel signature for
glueball detection is also discussed
Black hole thermalization rate from brane anti-brane model
We develop the quasi-particle picture for Schwarzchild and far from extremal
black holes. We show that the thermalization equations of the black hole is
recovered from the model of branes and anti-branes. This can also be viewed as
a field theory explanation of the relationship between area and entropy for
these black holes. As a by product the annihilation rate of branes and
anti-branes is computed.Comment: 11 pages, late
Polarization Observables in
We explore some of the rich structure of the polarization observables
recently developed for processes like and in the framework of a specific model for the latter process.
Emphasis is placed on observables that may be accesible at existing facilities
in the near future. The sensitivity of the observables to the details of the
model indicate that they will be a very useful tool in differentiating between
different models for reactions like these. In the framework of a model for
, we examine the sensitivity of the observables to
coupling constants of the , to the properties of the , and
to the existence of the .Comment: 21 pages, latex, 17 figures, 1 style file include
Strangeness and Chiral Symmetry Breaking
The implications of chiral symmetry breaking and SU(3) symmetry breaking have
been studied in the chiral constituent quark model (CQM). The role of
hidden strangeness component has been investigated for the scalar matrix
elements of the nucleon with an emphasis on the meson-nucleon sigma terms. The
CQM is able to give a qualitative and quantitative description of the
"quark sea" generation through chiral symmetry breaking. The significant
contribution of the strangeness is consistent with the recent available
experimental observations.Comment: 10 pages, 1 table. To appear in Mod. Phys. Lett.
Chiral Lagrangian Parameters for Scalar and Pseudoscalar Mesons
The results of a high-statistics study of scalar and pseudoscalar meson
propagators in quenched lattice QCD are presented. For two values of lattice
spacing, ( fm) and 5.9 ( fm), we
probe the light quark mass region using clover improved Wilson fermions with
the MQA pole-shifting ansatz to treat the exceptional configuration problem.
The quenched chiral loop parameters and are determined
from a study of the pseudoscalar hairpin correlator. From a global fit to the
meson correlators, estimates are obtained for the relevant chiral Lagrangian
parameters, including the Leutwyler parameters and . Using the
parameters obtained from the singlet and nonsinglet pseudoscalar correlators,
the quenched chiral loop effect in the nonsinglet scalar meson correlator is
studied. By removing this QCL effect from the lattice correlator, we obtain the
mass and decay constant of the ground state scalar, isovector meson .Comment: 36 pages, 12 figures, LaTe
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