11,296 research outputs found
Non-cancellation of electroweak logarithms in high-energy scattering
We study electroweak Sudakov corrections in high energy scattering, and the
cancellation between real and virtual Sudakov corrections. Numerical results
are given for the case of heavy quark production by gluon collisions involving
the rates . Gauge boson virtual corrections are related to real
transverse gauge boson emission, and Higgs virtual corrections to Higgs and
longitudinal gauge boson emission. At the LHC, electroweak corrections become
important in the TeV regime. At the proposed 100 TeV collider, electroweak
interactions enter a new regime, where the corrections are very large and need
to be resummed.Comment: 11 pages, 12 figures, 1 table. v2: Journal versio
Constraint equations for heavy-to-light currents in SCET
A complete basis for the next-to-next-to leading order heavy-to-light
currents in the soft-collinear effective theory is constructed.
Reparameterization invariance is imposed by deriving constraint equations.
Their solutions give the set of allowed Dirac structures as well as relations
between the Wilson coefficients of operators that appear at different orders in
the power expansion. The completeness of reparameterization invariance
constraints derived on a projected surface is investigated. We also discuss the
universality of the ultrasoft Wilson line with boundary conditions.Comment: 35 page
Global analysis of inclusive B decays
In light of the large amount of new experimental data, we revisit the
determination of V_{cb} and m_b from inclusive semileptonic and radiative B
decays. We study shape variables to order lqcd^3/m_b^3 and alpha_s^2\beta_0,
and include the order alpha_s, lqcd/m_b correction to the hadron mass spectrum
in semileptonic decay, which improves the agreement with the data. We focus on
the 1S and kinetic mass schemes for the b quark, with and without expanding
m_b-m_c in HQET. We perform fits to all available data from BABAR, BELLE, CDF,
CLEO, and DELPHI, discuss the theoretical uncertainties, and compare with
earlier results. We find V_{cb} = (41.4 +- 0.6 +- 0.1) x 10^{-3} and m_b^{1S} =
4.68 +- 0.03 GeV, including our estimate of the theoretical uncertainty in the
fit.Comment: 12 pages, 6 figures. Includes latest BELLE data on lepton and hadron
moments. Electromagnetic correction was improperly included in previous
versio
Equation of state for Entanglement in a Fermi gas
Entanglement distance is the maximal separation between two entangled
electrons in a degenerate electron gas. Beyond that distance, all entanglement
disappears. We relate entanglement distance to degeneracy pressure both for
extreme relativistic and non-relativistic systems, and estimate the
entanglement distance in a white dwarf. Treating entanglement as a
thermodynamical quantity, we relate the entropy of formation and concurrence to
relative electron distance, pressure, and temperature, to form a new equation
of state for entanglement.Comment: To appear in Phys. Rev. A., 4 pages, 1 figur
Helmholtz bright and boundary solitons
We report, for the first time, exact analytical boundary solitons of a generalized cubic-quintic Non-Linear Helmholtz (NLH) equation. These solutions have a linked-plateau topology that is distinct from conventional dark soliton solutions; their amplitude and intensity distributions are spatially delocalized and connect regions of finite and zero wave-field disturbances (suggesting also the classification as 'edge solitons'). Extensive numerical simulations compare the stability properties of recently-reported Helmholtz bright solitons, for this type of polynomial non-linearity, to those of the new boundary solitons. The latter are found to possess a remarkable stability characteristic, exhibiting robustness against perturbations that would otherwise lead to the destabilizing of their bright-soliton counterpart
Bayesian Analysis of Inflation III: Slow Roll Reconstruction Using Model Selection
We implement Slow Roll Reconstruction -- an optimal solution to the inverse
problem for inflationary cosmology -- within ModeCode, a publicly available
solver for the inflationary dynamics. We obtain up-to-date constraints on the
reconstructed inflationary potential, derived from the WMAP 7-year dataset and
South Pole Telescope observations, combined with large scale structure data
derived from SDSS Data Release 7. Using ModeCode in conjunction with the
MultiNest sampler, we compute Bayesian evidence for the reconstructed potential
at each order in the truncated slow roll hierarchy. We find that the data are
well-described by the first two slow roll parameters, \epsilon and \eta, and
that there is no need to include a nontrivial \xi parameter.Comment: 14 pages, 12 figures, minor changes; final version; accepted in PR
Semiclassics in the lowest Landau band
This paper deals with the comparison between the strong Thomas-Fermi theory
and the quantum mechanical ground state energy of a large atom confined to
lowest Landau band wave functions. Using the tools of microlocal semiclassical
spectral asymptotics we derive precise error estimates. The approach presented
in this paper suggests the definition of a modified strong Thomas-Fermi
functional, where the main modification consists in replacing the integration
over the variables perpendicular to the magnetic field by an expansion in
angular momentum eigenfunctions. The resulting DSTF theory is studied in detail
in the second part of the paper.Comment: Latex2e, 31 page
Enhanced nonperturbative effects in jet distributions
We consider the triple differential distribution
d\Gamma/(dE_J)(dm_J^2)(d\Omega_J) for two-jet events at center of mass energy
M, smeared over the endpoint region m_J^2 << M^2, |2 E_J -M| ~ \Delta, \lqcd <<
\Delta << M. The leading nonperturbative correction, suppressed by
\lqcd/\Delta, is given by the matrix element of a single operator. A similar
analysis is performed for three jet events, and the generalization to any
number of jets is discussed. At order \lqcd/\Delta, non-perturbative effects in
four or more jet events are completely determined in terms of two matrix
elements which can be measured in two and three jet events.Comment: Significant changes made. The first moment does not vanish--the paper
has been modified to reflect this. Relations between different numbers of
jets still hol
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