221 research outputs found
Initial Condition for QGP Evolution from NEXUS
We recently proposed a new approach to high energy nuclear scattering, which
treats the initial stage of heavy ion collisions in a sophisticated way.
We are able to calculate macroscopic quantities like energy density and
velocity flow at the end of this initial stage, after the two nuclei having
penetrated each other.
In other words, we provide the initial conditions for a macroscopic treatment
of the second stage of the collision.
We address in particular the question of how to incorporate the soft
component properly. We find almost perfect "Bjorken scaling": the rapidity
coincides with the space-time rapidity, whereas the transverse flow is
practically zero. The distribution of the energy density in the transverse
plane shows typically a very "bumpy" structure.Comment: 17 pages, 24 figure
Naturally split supersymmetry
Nonobservation of superparticles till date, new Higgs mass limits from the
CMS and ATLAS experiments, WMAP constraints on relic density, various other low
energy data, and the naturalness consideration, all considered simultaneously
imply a paradigm shift of supersymmetric model building. In this paper we
perform, for the first time, a detailed numerical study of brane-world induced
supersymmetry breaking for both minimal and next-to-minimal scenarios. We
observe that a naturally hierarchical spectrum emerges through an interplay of
bulk, brane-localized and quasi-localized fields, which can gain more relevance
in the subsequent phases of the LHC run.Comment: 6 pages, 6 eps figures; v2: minor updates, to appear in JHE
New Sum Rules from Low Energy Compton Scattering on Arbitrary Spin Target
We derive two sum rules by studying the low energy Compton scattering on a
target of arbitrary (nonzero) spin j. In the first sum rule, we consider the
possibility that the intermediate state in the scattering can have spin |j \pm
1| and the same mass as the target. The second sum rule applies if the theory
at hand possesses intermediate narrow resonances with masses different from the
mass of the scatterer. These sum rules are generalizations of the
Gerasimov-Drell-Hearn-Weinberg sum rule. Along with the requirement of tree
level unitarity, they relate different low energy couplings in the theory.
Using these sum rules, we show that in certain cases the gyromagnetic ratio can
differ from the "natural" value g=2, even at tree level, without spoiling
perturbative unitarity. These sum rules can be used as constraints applicable
to all supergravity and higher-spin theories that contain particles charged
under some U(1) gauge field. In particular, applied to four dimensional N=8
supergravity in a spontaneously broken phase, these sum rules suggest that for
the theory to have a good ultraviolet behavior, additional massive states need
to be present, such as those coming from the embedding of the N=8 supergravity
in type II superstring theory. We also discuss the possible implications of the
sum rules for QCD in the large-N_c limit.Comment: 18 pages, v2: discussion on black hole contribution is included,
references added; v3: extended discussion in introduction, version to appear
in JHE
Factorization and polarization in linearized gravity
We investigate all the four-body graviton interaction processes:
, , and with
as an elementary particle of spin less than two in the context of linearized
gravity except the spin-3/2 case. We show explicitly that gravitational gauge
invariance and Lorentz invariance cause every four-body graviton scattering
amplitude to be factorized. We explore the implications of this factorization
property by investigating polarization effects through the covariant density
matrix formalism in each four-body graviton scattering process.Comment: 45 pages, figures are included (uses pictex), RevTe
Non-Riemannian Gravity and the Einstein-Proca System
We argue that all Einstein-Maxwell or Einstein-Proca solutions to general
relativity may be used to construct a large class of solutions (involving
torsion and non-metricity) to theories of non-Riemannian gravitation that have
been recently discussed in the literature.Comment: 9 pages Plain Tex (No Figures), Letter to Editor Classical and
Quantum Gravit
Black Holes with Weyl Charge and Non-Riemannian Waves
A simple modification to Einstein's theory of gravity in terms of a
non-Riemannian connection is examined. A new tensor-variational approach yields
field equations that possess a covariance similar to the gauge covariance of
electromagnetism. These equations are shown to possess solutions analogous to
those found in the Einstein-Maxwell system. In particular one finds
gravi-electric and gravi-magnetic charges contributing to a spherically
symmetric static Reissner-Nordstr\"om metric. Such Weyl ``charges'' provide a
source for the non-Riemannian torsion and metric gradient fields instead of the
electromagnetic field. The theory suggests that matter may be endowed with
gravitational charges that couple to gravity in a manner analogous to
electromagnetic couplings in an electromagnetic field. The nature of
gravitational coupling to spinor matter in this theory is also investigated and
a solution exhibiting a plane-symmetric gravitational metric wave coupled via
non-Riemannian waves to a propagating spinor field is presented.Comment: 18 pages Plain Tex (No Figures), Classical and Quantum Gravit
Quantum Gravity
General lectures on quantum gravity.Comment: Lectures given at Karpacz. 40 pages, submitted to Lecture Notes in
Physics. Bigger figure
Seesaw Neutrino Signals at the Large Hadron Collider
We discuss the scenario with gauge singlet fermions (right-handed neutrinos)
accessible at the energy of the Large Hadron Collider. The singlet fermions
generate tiny neutrino masses via the seesaw mechanism and also have sizable
couplings to the standard-model particles. We demonstrate that these two facts,
which are naively not satisfied simultaneously, are reconciled in the
five-dimensional framework in various fashions, which make the seesaw mechanism
observable. The collider signal of tri-lepton final states with transverse
missing energy is investigated for two explicit examples of the observable
seesaw, taking account of three types of neutrino mass spectrum and the
constraint from lepton flavor violation. We find by showing the significance of
signal discovery that the collider experiment has a potential to find signals
of extra dimensions and the origin of small neutrino masses.Comment: 27 pages, 4 figure
Transmission of Supersymmetry Breaking from a 4-Dimensional Boundary
In the strong-coupling limit of the heterotic string theory constructed by
Horava and Witten, an 11-dimensional supergravity theory is coupled to matter
multiplets confined to 10-dimensional mirror planes. This structure suggests
that realistic unification models are obtained, after compactification of 6
dimensions, as theories of 5-dimensional supergravity in an interval, coupling
to matter fields on 4-dimensional walls. Supersymmetry breaking may be
communicated from one boundary to another by the 5-dimensional fields. In this
paper, we study a toy model of this communication in which 5-dimensional
super-Yang-Mills theory in the bulk couples to chiral multiplets on the walls.
Using the auxiliary fields of the Yang-Mills multiplet, we find a simple
algorithm for coupling the bulk and boundary fields. We demonstrate two
different mechanisms for generating soft supersymmetry breaking terms in the
boundary theory. We also compute the Casimir energy generated by supersymmetry
breaking.Comment: 26 pages, latex + 7 eps figures, final correction
2013 AAFP Feline Vaccination Advisory Panel Report
Rationale: This Report was developed by the Feline Vaccination Advisory Panel of the American Association of Feline Practitioners (AAFP) to provide practical recommendations to help clinicians select appropriate vaccination schedules for their feline patients based on risk assessment. The recommendations rely on published data as much as possible, as well as consensus of a multidisciplinary panel of experts in immunology, infectious disease, internal medicine and clinical practice
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