735,772 research outputs found
Little Higgs model effects in
Though the predictions of the Standard Model (SM) are in excellent agreement
with experiments there are still several theoretical problems associated with
the Higgs sector of the SM, where it is widely believed that some ``{\it new
physics}'' will take over at the TeV scale. One beyond the SM theory which
resolves these problems is the Little Higgs (LH) model. In this work we have
investigated the effects of the LH model on \gggg scattering
\cite{Choudhury:2006xa}.Comment: Talk given at LCWS06, Bangalore, 4 pages (style files included
Decays Z' -> \gamma\gamma\gamma{} and Z -> \gamma\gamma\gamma{} in the minimal 331 model
The possibility of a significant effect of exotic particles on the
Z'->\gamma\gamma\gamma{} and Z->\gamma\gamma\gamma{} decays is investigated in
the context of the minimal 331 model. This model, which is based in the
SU_C(3)xSU_L(3)xU_X(1) gauge group, predicts the existence of many exotic
charged particles that can significantly enhance the decay widths. It is found
that the standard model prediction for the Z->\gamma\gamma\gamma{} decay
remains essentially unchanged, as the new physics effects quickly decouples. On
the other hand, it is found that the contributions of the new exotic quarks and
gauge bosons predicted by this model lead to a branching fraction for the
Z'->\gamma\gamma\gamma{} decay of about 10^(-6), which is about three orders of
magnitude larger than that of the Z->\gamma\gamma\gamma{} decay.Comment: 20 pages and 20 figure
GAMMA; a simulation model for ageing, pensions and public finances
To answer policy questions that have intergenerational implications, a computable simulation model should obey four conditions, it should: incorporate long-term demographic developments; include a detailed modelling of the public sector; decompose the population into several generations; account for the behaviour of the various economic agents. This document describes and illustrates a model that meets all these conditions. It is an applied general equilibrium model that is based on generational accounting principles named GAMMA (Generational Accounting Model with Maximizing Agents).
Quantum-critical pairing with varying exponents
We analyse the onset temperature T_p for the pairing in cuprate
superconductors at small doping, when tendency towards antiferromagnetism is
strong. We consider the model of Moon and Sachdev (MS), which assumes that
electron and hole pockets survive in a paramagnetic phase. Within this model,
the pairing between fermions is mediated by a gauge boson, whose propagator
remains massless in a paramagnet. We relate the MS model to a generic
\gamma-model of quantum-critical pairing with the pairing kernel \lambda
(\Omega) \propto 1/\Omega^{\gamma}. We show that, over some range of
parameters, the MS model is equivalent to the \gamma-model with \gamma =1/3
(\lambda (\Omega) \propto \Omega^{-1/3}). We find, however, that the parameter
range where this analogy works is bounded on both ends. At larger deviations
from a magnetic phase, the MS model becomes equivalent to the \gamma-model with
varying \gamma >1/3, whose value depends on the distance to a magnetic
transition and approaches \gamma =1 deep in a paramagnetic phase. Very near the
transition, the MS model becomes equivalent to the \gamma-model with varying
\gamma <1/3. Right at the magnetic QCP, the MS model is equivalent to the
\gamma-model with \gamma =0+ (\lambda (\Omega) \propto \log \Omega), which is
the model for color superconductivity. Using this analogy, we verified the
formula for T_c derived for color superconductivity.Comment: 10 pages, 8 figures, submitted to JLTP for a focused issue on Quantum
Phase Transition
Resolved photon and multi-component model for p and scattering at high energies
We generalize our previous model for scattering to scattering. In the latter case the number of components naturally
grows. When using the model parameters from our previous analysis
the model cross section for scattering is larger than the
corresponding LEP2 experimental data by more than a factor of two. However,
performing a new simultaneous fit to and total
cross section we can find an optimal set of parameters to describe both
processes. We propose new measures of factorization breaking for collisions and present results for our new model.Comment: 23 pages, 10 figure
h \gamma \gamma Coupling in Higgs Triplet Model
We investigate Higgs boson decay into two photons in the type-II seesaw
model. The rate of gets suppressed/enhanced in this model
compared to the Standard Model (SM) due to the presence of the singly and
doubly charged Higgs and .Comment: Latex, 7 pages, 2 Figures. The 2011 International Workshop on Future
Linear Colliders (LCWS11), Granada, Spai
in an ACD model
We present a full calculation of the amplitudes for in a simple ACD model that extends an incomplete one in a previous
paper. We find cancellations between the contributions from different KK towers
and a small decrease relative to the SM predictions. It is conjectured that
radiative QCD corrections might actually lead to an enhancement in the
branching ratios and {\bf CP} asymmetries, but no more than modest ones.Comment: 3 pages, 2 figure
Two photon decay of neutral scalars below 1.5 GeV in a chiral model for bar{q}q and bar{q}bar{q}qq states
We study the two photon decay of neutral scalars below 1.5 GeV in the context
of a recently proposed chiral model for bar{q}q and bar{q}bar{q}qq states. We
find good agreement with experimental results for the a_{0}(980)->gamma gamma.
Our calculations for f_{0}(980)->gamma gamma shows that further work is
necessary in order to understand the structure of this meson. The model
predicts Gamma(a_{0}(1450)->gamma gamma)=0.16+/-0.10KeV, Gamma(sigma->gamma
gamma)=0.47+/-0.66 KeV, Gamma(f(1370)->gamma gamma)=0.07+/-0.15 KeV,
Gamma(f(1500)->gamma gamma)=0.74+/-0.78 KeV.Comment: 6 pages, 1 figur
- …