6,256 research outputs found
Heavy Meson Physics: What have we learned in Twenty Years?
I give a personal account of the development of the field of heavy quarks.
After reviewing the experimental discovery of charm and bottom quarks, I
describe how the field's focus shifted towards determination of CKM elements
and how this has matured into a precision science.Comment: This talk was presented during the ceremony awarding the Medalla 2003
of the Division of Particles and Fields of The Mexican Phsyical Society, at
the IX Mexican Workshop on Particles and Fields; submitted for proceedings; 9
pages, 9 figures; replacement: fix multiple typo
The CP asymmetry in B^0(t) -> K_S \pi^0 \gamma in the Standard Model
The time-dependent CP asymmetry in exclusive B^0(t) -> K^{*0}\gamma decays
has been proposed as a probe of new physics in B decays. Recently, this method
was extended to radiative decays into multibody hadronic final states such as
B^0(t)-> K_S\pi^0\gamma and B^0(t)-> \pi^+\pi^-\gamma. The CP asymmetry in
these decays vanishes to the extent that the photon is completely polarized. In
the Standard Model, the photon emitted in b-> s\gamma has high left-handed
polarization, but right-handed contamination enters already at leading order in
\Lambda/m_b even for vanishing light quark masses. We compute here the
magnitude of this effect and the time dependent CP asymmetry parameter S_{K_S
\pi^0\gamma}. We find that the Standard Model can easily accomodate values of S
as large as 10%, but a precise value cannot be obtained at present because of
strong interactions uncertainties.Comment: 11 pages, 4 figures. Final version to appear in Physical Review
Comment on ``Self-organized criticality and absorbing states: Lessons from the Ising model"
According to Pruessner and Peters [Phys. Rev. E {\bf 73}, 025106(R) (2006)],
the finite size scaling exponents of the order parameter in sandpile models
depend on the tuning of driving and dissipation rates with system size. We
point out that the same is not true for {\em avalanches} in the slow driving
limit.Comment: 3 pages, 1 figure, to appear in Phys. Rev.
Magnetic Wormholes and Vertex Operators
We consider wormhole solutions in Euclidean dimensions. A duality
transformation is introduced to derive a new action from magnetic wormhole
action of Gupta, Hughes, Preskill and Wise. The classical solution is
presented. The vertex operators corresponding to the wormhole are derived.
Conformally coupled scalars and spinors are considered in the wormhole
background and the vertex operators are computed. ( To be published in Phys.
Rev. D15)Comment: 18 pages of RevTex, preprint IP/BBSR/94-2
EWPD Constraints on Flavor Symmetric Vector Fields
Electroweak precision data constraints on flavor symmetric vector fields are
determined. The flavor multiplets of spin one that we examine are the complete
set of fields that couple to quark bi-linears at tree level while not initially
breaking the quark global flavor symmetry group. Flavor safe vector masses
proximate to, and in some cases below, the electroweak symmetry breaking scale
are found to be allowed. Many of these fields provide a flavor safe mechanism
to explain the t tbar forward backward anomaly, and can simultaneously
significantly raise the allowed values of the Standard Model Higgs mass
consistent with electroweak precision data.Comment: Matches version published in JHE
Systems with Multiplicative Noise: Critical Behavior from KPZ Equation and Numerics
We show that certain critical exponents of systems with multiplicative noise
can be obtained from exponents of the KPZ equation. Numerical simulations in 1d
confirm this prediction, and yield other exponents of the multiplicative noise
problem. The numerics also verify an earlier prediction of the divergence of
the susceptibility over an entire range of control parameter values, and show
that the exponent governing the divergence in this range varies continuously
with control parameter.Comment: Four pages (In Revtex format) with 4 figures (in Postcript
Strong Couplings of X(3872)_{J=1,2} and a New Look at J/psi Suppression in Heavy Ion Collisions
We define and compute from data the strong couplings of the X(3872) with both
of the possible quantum numbers assignments J^{PC}=1^{++},2^{-+}. We use these
to compute cross sections for J/psi resonance scattering into D Dbar*. As an
application of the results obtained we revise the calculation of the J/psi
absorption in a hot hadron gas to confront with recent RHIC observations in
Au-Au collisions.Comment: 23 pages, 18 figures, 4 table
Phase separation in systems with absorbing states
We study the problem of phase separation in systems with a positive definite
order parameter, and in particular, in systems with absorbing states. Owing to
the presence of a single minimum in the free energy driving the relaxation
kinetics, there are some basic properties differing from standard phase
separation. We study analytically and numerically this class of systems; in
particular we determine the phase diagram, the growth laws in one and two
dimensions and the presence of scale invariance. Some applications are also
discussed.Comment: Submitted to Europhysics Let
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