2,013 research outputs found
The Invisible Higgs Decay Width in the Add Model at the LHC
Assuming flat universal extra dimensions, we demonstrate that for a light
Higgs boson the process will be observable at the level at the LHC for the
portion of the Higgs-graviscalar mixing () and effective Planck mass
() parameter space where channels relying on visible Higgs decays fail to
achieve a signal. Further, we show that even for very modest values
of the invisible decay signal probes to higher than does the
(-independent) jets/\gam + missing energy signal from graviton
radiation. We also discuss various effects, such as Higgs decay to two
graviscalars, that could become important when is of order 1.Comment: 6 pages, 2 figures, To appear in the Proceedings of the Les Houches
Workshop 2003: ``Physics at TeV Colliders'', ed. F. Boudjem
From hidden symmetry to extra dimensions: a five dimensional formulation of the Degenerate BESS model
We consider the continuum limit of a moose model corresponding to a
generalization to N sites of the Degenerate BESS model. The five dimensional
formulation emerging in this limit is a realization of a RS1 type model with
SU(2)_L x SU(2)_R in the bulk, broken by boundary conditions and a vacuum
expectation value on the infrared brane. A low energy effective Lagrangian is
derived by means of the holographic technique and corresponding bounds on the
model parameters are obtained.Comment: Latex file, 40 pages and 5 figure
Top-BESS model and its phenomenology
We introduce the top-BESS model which is the effective description of the
strong electroweak symmetry breaking with a single new SU(2)_L+R triplet vector
resonance. The model is a modification of the BESS model in the fermion sector.
The triplet couples to the third generation of quarks only. This approach
reflects a possible extraordinary role of the top quark in the mechanism of
electroweak symmetry breaking. The low-energy limits on the model parameters
found provide hope for finding sizable signals in the LHC Drell-Yan processes
as well as in the s-channel production processes at the ILC. However, there are
regions of the model parameter space where the interplay of the direct and
indirect fermion couplings can hide the resonance peak in a scattering process
even though the resonance exists and couples directly to top and bottom quarks.Comment: published in Physical Review D, minor changes in text, 21 pages, 37
figure
Vortex and half-vortex dynamics in a spinor quantum fluid of interacting polaritons
Spinorial or multi-component Bose-Einstein condensates may sustain fractional
quanta of circulation, vorticant topological excitations with half integer
windings of phase and polarization. Matter-light quantum fluids, such as
microcavity polaritons, represent a unique test bed for realising strongly
interacting and out-of-equilibrium condensates. The direct access to the phase
of their wavefunction enables us to pursue the quest of whether half vortices
---rather than full integer vortices--- are the fundamental topological
excitations of a spinor polariton fluid. Here, we are able to directly generate
by resonant pulsed excitations, a polariton fluid carrying either the half or
full vortex states as initial condition, and to follow their coherent evolution
using ultrafast holography. Surprisingly we observe a rich phenomenology that
shows a stable evolution of a phase singularity in a single component as well
as in the full vortex state, spiraling, splitting and branching of the initial
cores under different regimes and the proliferation of many vortex anti-vortex
pairs in self generated circular ripples. This allows us to devise the
interplay of nonlinearity and sample disorder in shaping the fluid and driving
the phase singularities dynamicsComment: New version complete with revised modelization, discussion and added
material. 8 pages, 7 figures. Supplementary videos:
https://drive.google.com/folderview?id=0B0QCllnLqdyBfmc2ai0yVF9fa2g2VnZodGUwemVkLThBb3BoOVRKRDJMS2dUdjlZdkRTQk
Consequences of a covariant Description of Heavy Ion Reactions at intermediate Energies
Heavy ion collisions at intermediate energies are studied by using a new RQMD
code, which is a covariant generalization of the QMD approach. We show that
this new implementation is able to produce the same results in the
nonrelativistic limit (i.e. 50MeV/nucl.) as the non-covariant QMD. Such a
comparison is not available in the literature. At higher energies (i.e. 1.5
GeV/nucl. and 2 GeV/nucl.) RQMD and QMD give different results in respect to
the time evolution of the phase space, for example for the directed transverse
flow. These differences show that consequences of a covariant description of
heavy ion reactions within the framework of RQMD are existing even at
intermediate energies.Comment: LaTex-file, 28 pages, 8 figures (available upon request), accepted
for publication in Physical Review
The Coronavirus Pandemic: A Pitfall or a Fast Track for Validating Cell Therapy Products?
The global COVID-19 pandemic has prompted urgent need for potential therapies for severe respiratory consequences resulting from coronavirus infection. New therapeutic agents that will attenuate ongoing inflammation and at the same time promote regeneration of injured lung epithelial cells are urgently needed. Cell-based therapies, primarily involving mesenchymal stromal cells (MSCs) and their derivatives, are currently investigated worldwide for SARS-CoV-2-induced lung diseases. A significant number of academic centers and companies globally have already initiated such trials. However, at a time of unprecedented need, it is also foreseen that families and caregivers will seek all available options, including access to cell-based and other investigational products, even before proven safety and efficacy as well as regulatory approval. This should not be an excuse for opportunists to sell or advertise unproven therapies of any kind. "Compassionate use" should be conducted in the context of a clinical investigation framed by strict ethical and regulatory permissions, with the goal of obtaining mechanistic information wherever possible
Ultrafast control of Rabi oscillations in a polariton condensate
We report the experimental observation and control of space and time-resolved
light-matter Rabi oscillations in a microcavity. Our setup precision and the
system coherence are so high that coherent control can be implemented with
amplification or switching off of the oscillations and even erasing of the
polariton density by optical pulses. The data is reproduced by a fundamental
quantum optical model with excellent accuracy, providing new insights on the
key components that rule the polariton dynamics.Comment: 5 pages, 3 figures, supplementary 7 pages, 4 figures. Supplementary
videos:
https://drive.google.com/folderview?id=0B0QCllnLqdyBNjlMLTdjZlNhbTQ&usp=sharin
Singular lagrangians: some geometric structures along the Legendre map
New geometric structures that relate the lagrangian and hamiltonian
formalisms defined upon a singular lagrangian are presented. Several vector
fields are constructed in velocity space that give new and precise answers to
several topics like the projectability of a vector field to a hamiltonian
vector field, the computation of the kernel of the presymplectic form of
lagrangian formalism, the construction of the lagrangian dynamical vector
fields, and the characterisation of dynamical symmetries.Comment: 27 pages; minor changes, a reference update
Part 1: Defining unproven cellular therapies
Given the potential of cell-based products, including
stem/progenitor cells and immune cells, there is a global
effort to introduce these therapies into the clinic to
correct organ dysfunctions, to treat cancer and to abrogate
autoimmune diseases and a wide variety of
pathological conditions [1–3]. Relatively easy access
to these cells, obtained from marrow, adipose, cord
blood and other human tissues, provides tremendous
opportunity for translational research, particularly
for indications with no satisfactory medical solution
for patients with “unmet medical needs.” Prenatal and
adult stem cells (including induced pluripotent stem
cells have significant potential to rebuild tissues and
correct dysfunctional organs in human diseases
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