3,477 research outputs found
The dynamics of the semicircular canals
Transfer functions derived for theoretical dynamic responses of semicircular canals defined by differential equatio
One-loop renormalisation of the NMSSM in SloopS : 1. the neutralino-chargino and sfermion sectors
We have completed the one-loop renormalisation of the Next-to-Minimal
Supersymmetric Standard Model (NMSSM) allowing for and comparing between
different renormalisation schemes. A special attention is paid to on-shell
schemes. We study a variety of these schemes based on alternative choices of
the physical input parameters. In this paper we present our approach to the
renormalisation of the NMSSM and report on our results for the
neutralino-chargino and sfermion sectors. We will borrow some results from our
study of the Higgs sector whose full discussion is left for a separate
publication. We have implemented the set up for all the sectors of the NMSSM
within \sloops, a code for the automatic computation of one-loop corrections
initially developed for the standard model and the MSSM. Among the many
applications that allows the code, we present here the one-loop corrections to
neutralino masses and to partial widths of neutralinos and charginos into final
states with one gauge boson. One-loop electroweak and QCD corrections to the
partial widths of third generation sfermions into a fermion and a chargino or a
neutralino are also computed.Comment: 44 page
micrOMEGAs : a tool for dark matter studies
micrOMEGAs is a tool for cold dark matter (DM) studies in generic extensions
of the standard model with a R-parity like discrete symmetry that guarantees
the stability of the lightest odd particle. The code computes the DM relic
density, the elastic scattering cross sections of DM on nuclei relevant for
direct detection, and the spectra of positrons, anti-protons and photons
originating from DM annihilation including porpagation of charged cosmic rays.
The cross sections and decay properties of new particles relevant for collider
studies are included as well as constraints from the flavour sector on the
parameter space of supersymmetric models.Comment: 10 pages, Proceedings of LC09, e+e- Physics at the TeV scale and the
Dark Matter connection, Perugia, Italy, 21-24 sept. 200
Z radiation off stops at a linear collider
We calculate e+e- --> stop/stop/Z at a linear collider. For large splitting
between the two stops the cross-section is sensitive to the value of m(stop2)
when this particle is too heavy to be directly produced. The results are
compared to e+e- --> stop/stop/h.Comment: 19 pages, 8 figure
micrOMEGAs: Version 1.3
We present the latest version of micromegas, a code that calculates the relic
density of the lightest supersymmetric particle in the MSSM. All tree-level
processes for the annihilation of the LSP are included as well as all possible
coannihilation processes with neutralinos, charginos, sleptons, squarks and
gluinos. The cross-sections extracted from CalcHEP are calculated exactly using
loop-corrected masses and mixings as specified in the SUSY Les Houches Accord.
Relativistic formulae for the thermal average are used and care is taken to
handle poles and thresholds by adopting specific integration routines. The
input parameters can be either the soft SUSY parameters in a general MSSM or
the parameters of a SUGRA model specified at some high scale (GUT). In the
latter case, a link with Suspect, Softsusy, Spheno and Isajet allows to
calculate the supersymmetric spectrum, Higgs masses, as well as mixing
matrices. Higher-order corrections to Higgs couplings to quark pairs including
QCD as well as some SUSY corrections (deltaMb) are implemented. Routines
calculating (g-2), bsgamma and bsmumu are also included. In particular the
bsgamma routine includes an improved NLO for the SM and the charged Higgs while
the SUSY large tan(beta) effects beyond leading-order are included. This new
version also provides cross-sections for any 2->2 process as well as partial
decay widths for two-body final states in the MSSM allowing for easy simulation
at colliders.Comment: 45 page
micrOMEGAs: recent developments
The program micrOMEGAs that calculates the relic density of the lightest
supersymmetric particle (LSP) in the MSSM is presented. The impact of
coannihilation channels and of higher order corrections to Higgs widths is
stressed. The dependence on the RGE code used to calculate the soft parameters
is also discussed.Comment: 5 pages, 2 figures, Talk presented at IDM2002, York, England;
Reference adde
micrOMEGAs4.1: two dark matter candidates
micrOMEGAs is a code to compute dark matter observables in generic extensions
of the standard model. This version of micrOMEGAs includes a generalization of
the Boltzmann equations to take into account the possibility of two dark matter
candidates. The modification of the relic density calculation to include
interactions between the two DM sectors as well as semi-annihilation is
presented. Both DM signals in direct and indirect detection are computed as
well. An extension of the standard model with two scalar doublets and a singlet
is used as an example.Comment: 13 pages, 1 figur
Universal aging properties at a disordered critical point
We investigate, analytically near the dimension and numerically in
, the non equilibrium relaxational dynamics of the randomly diluted Ising
model at criticality. Using the Exact Renormalization Group Method to one loop,
we compute the two times correlation function and Fluctuation
Dissipation Ratio (FDR) for any Fourier mode of the order parameter, of finite
wave vector . In the large time separation limit, the FDR is found to reach
a non trivial value independently of (small) and coincide with
the FDR associated to the the {\it total} magnetization obtained previously.
Explicit calculations in real space show that the FDR associated to the {\it
local} magnetization converges, in the asymptotic limit, to this same value
. Through a Monte Carlo simulation, we compute the autocorrelation
function in three dimensions, for different values of the dilution fraction
at . Taking properly into account the corrections to scaling, we find,
according to the Renormalization Group predictions, that the autocorrelation
exponent is independent on . The analysis is complemented by a
study of the non equilibrium critical dynamics following a quench from a
completely ordered state.Comment: 8 pages, 5 figure
Some remarks on the GNS representations of topological -algebras
After an appropriate restatement of the GNS construction for topological
-algebras we prove that there exists an isomorphism among the set
\cycl(A) of weakly continuous strongly cyclic -representations of a
barreled dual-separable -algebra with unit , the space \hilb_A(A^*) of
the Hilbert spaces that are continuously embedded in and are
-invariant under the dual left regular action of and the set of the
corresponding reproducing kernels. We show that these isomorphisms are cone
morphisms and we prove many interesting results that follow from this fact. We
discuss how these results can be used to describe cyclic representations on
more general inner product spaces.Comment: 34 pages. Minor changes. To appear in J. Math. Phys. 49 (4) Apr-0
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