41 research outputs found
The missing sinks: slip localization in faults, damage zones, and the seismic energy budget
No abstract available
Semileptonic and nonleptonic B decays to three charm quarks: B->J/psi (eta_c) D l nu and J/psi (eta_c) D pi
We evaluate the form factors describing the semileptonic decays , within the framework of a QCD
relativistic potential model. This decay is complementary to in a phase space region where a pion factors out.We
estimate the branching ratio for these semileptonic and nonleptonic channels,
finding ,
and .Comment: 14 pages, 4 figure
Exploring skewed parton distributions with two body models on the light front II: covariant Bethe-Salpeter approach
We explore skewed parton distributions for two-body, light-front wave
functions. In order to access all kinematical regimes, we adopt a covariant
Bethe-Salpeter approach, which makes use of the underlying equation of motion
(here the Weinberg equation) and its Green's function. Such an approach allows
for the consistent treatment of the non-wave function vertex (but rules out the
case of phenomenological wave functions derived from ad hoc potentials). Our
investigation centers around checking internal consistency by demonstrating
time-reversal invariance and continuity between valence and non-valence
regimes. We derive our expressions by assuming the effective qq potential is
independent of the mass squared, and verify the sum rule in a non-relativistic
approximation in which the potential is energy independent. We consider
bare-coupling as well as interacting skewed parton distributions and develop
approximations for the Green's function which preserve the general properties
of these distributions. Lastly we apply our approach to time-like form factors
and find similar expressions for the related generalized distribution
amplitudes.Comment: 25 pages, 12 figures, revised (minor changes but essential to
consistency
Semi-Analytic Approach to Higher-Order Corrections in Simple Muonic Bound Systems: Vacuum Polarization, Self-Energy and Radiative-Recoil
The current discrepancy of theory and experiment observed recently in muonic
hydrogen necessitates a reinvestigation of all corrections to contribute to the
Lamb shift in muonic hydrogen muH, muonic deuterium muD, the muonic 3He ion, as
well as in the muonic 4He ion. Here, we choose a semi-analytic approach and
evaluate a number of higher-order corrections to vacuum polarization (VP)
semi-analytically, while remaining integrals over the spectral density of VP
are performed numerically. We obtain semi-analytic results for the second-order
correction, and for the relativistic correction to VP. The self-energy
correction to VP is calculated, including the perturbations of the Bethe
logarithms by vacuum polarization. Subleading logarithmic terms in the
radiative-recoil correction to the 2S-2P Lamb shift of order alpha (Zalpha)^5
mu^3 ln(Zalpha)/(m_mu m_N) are also obtained. All calculations are
nonperturbative in the mass ratio of orbiting particle and nucleus.Comment: 10 pages; svjour style; to appear in the European Physical Journal
Baryon Tri-local Interpolating Fields
We systematically investigate tri-local (non-local) three-quark baryon fields
with U_L(2)*U_R(2) chiral symmetry, according to their Lorentz and isospin
(flavor) group representations. We note that they can also be called as
"nucleon wave functions" due to this full non-locality. We study their chiral
transformation properties and find all the possible chiral multiplets
consisting J=1/2 and J=3/2 baryon fields. We find that the axial coupling
constant |g_A| = 5/3 is only for nucleon fields belonging to the chiral
representation (1/2,1)+(1,1/2) which contains both nucleon fields and Delta
fields. Moreover, all the nucleon fields belonging to this representation have
|g_A| = 5/3.Comment: 8 pages, 3 tables, accepted by EPJ
Transition Form Factor up to within the Factorization Approach
In the paper, we apply the factorization approach to deal with the
transition form factor in the large recoil
regions. The B-meson wave functions and that include the
three-particle Fock states' contributions are adopted to give a consistent PQCD
analysis of the form factor up to . It has been found that
both the wave functions and can give sizable
contributions to the form factor and should be kept for a better understanding
of the meson decays. Then the contributions from different twist structures
of the kaon wavefunction are discussed, including the -breaking
effects. A sizable contribution from the twist-3 wave function is
found, whose model dependence is discussed by taking two group of parameters
that are determined by different distribution amplitude moments obtained in the
literature. It is also shown that and
, which are more
reasonable and consistent with the light-cone sum rule results in the large
recoil regions.Comment: 22 pages and 6 figure
Isgur-Wise Function for in B-S Approach
In the heavy quark limit, the heavy baryon (Q=b or c) can be
regarded as composed of a heavy quark and a scalar light diquark which has good
spin and flavor quantum numbers. Based on this picture we establish the
Bethe-Salpeter (B-S) equation for in the leading order of
expansion. With the kernel containing both the scalar confinement and
one-gluon-exchange terms we solve the B-S equation numerically. The Isgur-Wise
function for is obtained numerically from our model.
Comparison with other model calculations are also presented. It seems that the
Isgur-Wise function for drops faster than that for . The differential and total decay widths for are given in the limit .Comment: 14 pages, 4 Postscript figure
Heavy quarkonium: progress, puzzles, and opportunities
A golden age for heavy quarkonium physics dawned a decade ago, initiated by
the confluence of exciting advances in quantum chromodynamics (QCD) and an
explosion of related experimental activity. The early years of this period were
chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in
2004, which presented a comprehensive review of the status of the field at that
time and provided specific recommendations for further progress. However, the
broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles
could only be partially anticipated. Since the release of the YR, the BESII
program concluded only to give birth to BESIII; the -factories and CLEO-c
flourished; quarkonium production and polarization measurements at HERA and the
Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the
deconfinement regime. All these experiments leave legacies of quality,
precision, and unsolved mysteries for quarkonium physics, and therefore beg for
continuing investigations. The plethora of newly-found quarkonium-like states
unleashed a flood of theoretical investigations into new forms of matter such
as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the
spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b},
and b\bar{c} bound states have been shown to validate some theoretical
approaches to QCD and highlight lack of quantitative success for others. The
intriguing details of quarkonium suppression in heavy-ion collisions that have
emerged from RHIC have elevated the importance of separating hot- and
cold-nuclear-matter effects in quark-gluon plasma studies. This review
systematically addresses all these matters and concludes by prioritizing
directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K.
Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D.
Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A.
Petrov, P. Robbe, A. Vair