789 research outputs found
Sgoldstino events in top decays at LHC
We study top-quark decays in models with light sgoldstinos. The off-diagonal
entries in the squark mass matrices can lead to FCNC top two-body decays into
sgoldstinos and u(c) quarks. We compute the rates for these decays and discuss
the corresponding signatures that could manifest the presence of sgoldstinos in
top decays at LHC. We expect that a supersymmetry breaking scale up
to a scale of order 10 TeV could be probed through this process, for a maximal
squark mixing with the third generation. Justified by our preliminary analysis,
a thorough study of the corresponding signal versus background and systematics
in the LHC environment would be most welcome, in order to accurately assess the
potential of this promising process in determining .Comment: Standard LaTeX, 11 pages, 4 figures, one reference adde
Sparticle Spectrum and Dark Matter in M-Theory
The phenomenological implications of the eleven dimensional limit of
-theory (strongly coupled ) are investigated. In particular
we calculate the supersymmetric spectrum subject to constraints of correct
electroweak symmetry breaking and the requirement that the lighest
supersymmetric particle provides the dark matter of the universe. The -soft
term associated with the generation of a term in the superpotential is
calculated and its phenomenology is discussed.Comment: LaTeX file 15 pages,1 figure adde
Looking for a heavy wino LSP in collider and dark matter experiments
We investigate the phenomenology of a wino LSP as obtained in AMSB and some
string models. The WMAP constraint on the DM relic density implies a wino LSP
mass of 2.0-2.3 TeV. We find a viable signature for such a heavy wino at CLIC,
operating at its highest CM energy of 5 TeV. One also expects a viable
monochromatic -ray signal from its pair-annihilation at the galactic
centre at least for cuspy DM halo profiles.Comment: A discussion on non-perturbative effects on annihilation cross
section of TeV scale wino LSP added. Version to appear in Phys. Rev. D
Proton Stability and Dark Matter in a Realistic String MSSM
We demonstrate the existence of an extra nonanomalous U(1) gauge symmetry in
a three-generation Pati-Salam model constructed with intersecting D6-branes in
Type IIA string theory on a T^6/(Z_2 \times Z_2) orientifold. This extra U(1)
forbids all dimension-4, 5, and 6 operators which mediate proton decay in the
MSSM. Moreover, this results in the effective promotion of baryon and lepton
number to local gauge symmetries, which can potentially result in leptophobic
and leptophilic bosons observable at the LHC. Furthermore, it is not
necessary to invoke R-parity to forbid the dimension-4 operators which allow
rapid proton decay. However, R-parity may arise naturally from a spontaneously
broken U(1)_{B-L}. Assuming the presence of R-parity, we then study the direct
detection cross-sections for neutralino dark matter, including the latest
constraints from the XENON100 experiment. We find that these limits are now
within required range necessary to begin testing the model.Comment: Expanded discussion of Z' boson phenomenology. Accepted for
publication to Physical Review D. arXiv admin note: text overlap with
arXiv:1103.603
Nonlinear Realizations of Supersymmetry and Other Symmetries
Simultaneous nonlinear realizations of spontaneously broken supersymmetry in
conjunction with other spontaneous and/or explicitly broken symmetries
including R symmetry, global chiral symmetry, dilatations and the
superconformal symmetries is reviewed.Comment: 15 pages, invited brief review for Mod. Phys. Lett.
Supersymmetric Musings on the Predictivity of Family Symmetries
We discuss the predictivity of family symmetries for the soft supersymmetry
breaking parameters in the framework of supergravity. We show that unknown
details of the messenger sector and the supersymmetry breaking hidden sector
enter into the soft parameters, making it difficult to obtain robust
predictions. We find that there are specific choices of messenger fields which
can improve the predictivity for the soft parameters.Comment: 20 pages, 5 figure
Re-examination of Electroweak Symmetry Breaking in Supersymmetry and Implications for Light Superpartners
We examine arguments that could avoid light superpartners as an implication
of supersymmetric radiative electroweak symmetry breaking. We argue that, from
the point of view of string theory and standard approaches to generating the
mu-term, cancellations among parameters are not a generic feature. While the
coefficients relating the Z-mass to parameters in the soft supersymmetry
breaking Lagrangian can be made smaller, these same mechanisms lead to lighter
superpartner masses at the electroweak scale. Consequently we strengthen the
implication that gluinos, neutralinos, and charginos are light and likely to be
produced at the Fermilab Tevatron and a linear collider.Comment: 27 pages, 3 figure
One Loop Soft Supersymmetry Breaking Terms in Superstring Effective Theories
We perform a systematic analysis of soft supersymmetry breaking terms at the
one loop level in a large class of string effective field theories. This
includes the so-called anomaly mediated contributions. We illustrate our
results for several classes of orbifold models. In particular, we discuss a
class of models where soft supersymmetry breaking terms are determined by quasi
model independent anomaly mediated contributions, with possibly non-vanishing
scalar masses at the one loop level. We show that the latter contribution
depends on the detailed prescription of the regularization process which is
assumed to represent the Planck scale physics of the underlying fundamental
theory. The usual anomaly mediation case with vanishing scalar masses at one
loop is not found to be generic. However gaugino masses and A-terms always
vanish at tree level if supersymmetry breaking is moduli dominated with the
moduli stabilized at self-dual points, whereas the vanishing of the B-term
depends on the origin of the mu-term in the underlying theory. We also discuss
the supersymmetric spectrum of O-I and O-II models, as well as a model of
gaugino condensation. For reference, explicit spectra corresponding to a Higgs
mass of 114 GeV are given. Finally, we address general strategies for
distinguishing among these models.Comment: 49 pages: includes three tables and nine figure
CP-violating phases in the CKM matrix in orbifold compactifications
The picture of CP-violation in orbifold compactifications in which the
-modulus is at a complex fixed point of the modular group is studied.
CP-violation in the neutral kaon system and in the neutron electric dipole
moment are both discussed. The situation where the -modulus takes complex
values on the unit circle which are not at a fixed point is also discussed.Comment: LaTeX file 17 page
Vehicle routing for public transport with adapted simulated annealing
This paper presents an Adapted Simulated Annealing (ASA) algorithm to solve an instance of the vehicle routing problem (VRP): the intercity public transport problem (IPTP). This combinatorial optimization problem was effectively solved by means of a robust method. Its performance was achieved thanks to the incorporation of an auxiliary memory and a novel choice of the neighbours. The model is based on initial random solutions capable of generating appropriate bus routes and frequencies in a large solution space. We have established a search strategy that provides excellent responses at the process level. The intercity line linking Bahía Blanca and Punta Alta was chosen with the intention of evaluating ASA performance. The real traffic-behavior has been represented by means of the simulation software called SUMO. The computational results clearly indicate that the proposed approach constitutes an improvement in the ability to search for high quality solutions that facilitates the convergence.Fil: Rodriguez, D. A.. Universidad Nacional de Salta. Facultad de Ciencias Exactas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahia Blanca. Planta Piloto de Ingeniería Química (I). Grupo Vinculado al Plapiqui - Investigación y Desarrollo en Tecnología Química; Argentina. Universidad Nacional del Sur. Departamento de Ciencias e Ingeniería de la Computación. Laboratorio de Investigación y Desarrollo en Computación Científica; ArgentinaFil: Olivera, Ana Carolina. Universidad Nacional del Sur. Departamento de Ciencias e Ingeniería de la Computación. Laboratorio de Investigación y Desarrollo en Computación Científica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Brignole, Nélida Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahia Blanca. Planta Piloto de Ingeniería Química (I). Grupo Vinculado al Plapiqui - Investigación y Desarrollo en Tecnología Química; Argentina. Universidad Nacional del Sur. Departamento de Ciencias e Ingeniería de la Computación. Laboratorio de Investigación y Desarrollo en Computación Científica; Argentin
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