9,015 research outputs found
Study of Wgamma events at the CMS with 7 TeV LHC data
The measurement of the inclusive cross section for Wgamma production is
presented based on 36/ pb of data acquired with the CMS detector from 7 TeV LHC
collisions in 2010. Comparisons are made with the predictions of the standard
model. The W bosons are identified through their leptonic decays to electrons
and muons. The Wgamma cross section is sensitive to anomalous triple-gauge
couplings and hence this measurement probes physics beyond the standard model.Comment: Proceedings of talk given at Rencontres de Moriond, EWK session, La
Thuile, Italy, 2011, on behalf of the CMS collaboration. 5 pages, 4 figure
Universality in Fluid Domain Coarsening: The case of vapor-liquid transition
Domain growth during the kinetics of phase separation is studied following
vapor-liquid transition in a single component Lennard-Jones fluid. Results are
analyzed after appropriately mapping the continuum snapshots obtained from
extensive molecular dynamics simulations to a simple cubic lattice. For near
critical quench interconnected domain morphology is observed. A brief period of
slow diffusive growth is followed by a linear viscous hydrodynamic growth that
lasts for an extended period of time. This result is in contradiction with
earlier inclusive reports of late time growth exponent 1/2 that questions the
uniqueness of the non-equilibrium universality for liquid-liquid and
vapor-liquid transitions.Comment: 6 pages, 5 figure
Elastic energy loss and longitudinal straggling of a hard jet
The elastic energy loss encountered by jets produced in deep-inelastic
scattering (DIS) off a large nucleus is studied in the collinear limit. In
close analogy to the case of (non-radiative) transverse momentum broadening,
which is dependent on the medium transport coefficient , a class of
medium enhanced higher twist operators which contribute to the non-radiative
loss of the forward light-cone momentum of the jet () are identified and
the leading correction in the limit of asymptotically high is isolated.
Based on these operator products, a new transport coefficient is
motivated which quantifies the energy loss per unit length encountered by the
hard jet. These operator products are then computed, explicitly, in the case of
a similar hard jet traversing a deconfined quark-gluon-plasma (QGP) in the
hard-thermal-loop (HTL) approximation. This is followed by an evaluation of
sub-leading contributions which are suppressed by the light-cone momentum
, which yields the longitudinal "straggling" i.e., a slight change in
light cone momentum due to the Brownian propagation through a medium with a
fluctuating color field.Comment: 5 pages, 1 figure, Revtex
Cherenkov Radiation from Jets in Heavy-ion Collisions
The possibility of Cherenkov-like gluon bremsstrahlung in dense matter is
studied. We point out that the occurrence of Cherenkov radiation in dense
matter is sensitive to the presence of partonic bound states. This is
illustrated by a calculation of the dispersion relation of a massless particle
in a simple model in which it couples to two different massive resonance
states. We further argue that detailed spectroscopy of jet correlations can
directly probe the index of refraction of this matter, which in turn will
provide information about the mass scale of these partonic bound states.Comment: 4 pages, 5 figures, revte
A study of a NLO matrix element generator for Wgamma and matching scheme for NLO events and PYTHIA parton shower
We compare a NLO W gamma matrix element generator with the leading order
calculation in Pythia . A matching scheme between a next-to-leading order W
gamma matrix element generator by Baur et. al. and the Pythia parton shower is
presented. The NLO package produces W gamma+0 jet and W gamma+1jet final states
in the hard scattering and the objective is to consistently match these to the
initial state radiation from Pythia parton shower. The proposed methodology
preserves both the rate of the hard scattering process as well as various
kinematic distributions of experimental interest.Comment: 16 pages, 12 figures, 2 tables, 8 references, an abbreviated version
to appear in the proceedings of Physics at TeV Colliders, Les Houches 8-26
June 200
Orientifolds of type IIA strings on Calabi-Yau manifolds
We identify type IIA orientifolds that are dual to M-theory compactifications
on manifolds with G_2-holonomy. We then discuss the construction of crosscap
states in Gepner models. (Based on a talk presented by S.G. at PASCOS 2003 held
at the Tata Institute of Fundamental Research, Mumbai during Jan. 3-8, 2003.)Comment: 3 pages, RevTeX, PASCOS '03 tal
Study of Beta Equilibrated 2+1 Flavor Quark Matter in PNJL Model
We report a first case study of the phase diagram of 2+1 flavor strongly
interacting matter in equilibrium, using the
PolyakovNambuJona-Lasinio model. Physical characteristics of relevant
thermodynamic observables have been discussed. A comparative analysis with the
corresponding observables in the Nambu-Jona-Lasinio model is presented. We find
distinct differences between the models in terms of a number of thermodynamic
quantities like the speed of sound, specific heat, various number densities as
well as entropy. The present study is expected to give us a better insight into
the role that the superdense matter created in heavy ion collision experiments
play in our understanding of the properties of matter inside the core of
supermassive stars in the Universe
On the imaginary parts and infrared divergences of two-loop vector boson self-energies in thermal QCD
We calculate the imaginary part of the retarded two-loop self-energy of a
static vector boson in a plasma of quarks and gluons of temperature T, using
the imaginary time formalism. We recombine various cuts of the self-energy to
generate physical processes. We demonstrate how cuts containing loops may be
reinterpreted in terms of interference between Order tree diagrams and
the Born term along with spectators from the medium. We apply our results to
the rate of dilepton production in the limit of dilepton invariant mass E>>T.
We find that all infrared and collinear singularities cancel in the final
result obtained in this limit.Comment: references added, typos corrected, slightly abridged, version
accepted for publication in Phys. Rev.
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