1,298 research outputs found
Non-universal Z' from SO(10) GUTs with vector-like family and the origin of neutrino masses
A gauge boson with mass around the (few) TeV scale is a popular example
of physics beyond the Standard Model (SM) and can be a fascinating remnant of a
Grand Unified Theory (GUT). Recently, models with non-universal couplings
to the SM fermions due to extra vector-like states have received attention as
potential explanations of the present , anomalies; this
includes GUT model proposals based on the group. In this
paper we further develop GUT models with a flavour non-universal low scale
and clarify several outstanding issues within them. First, we successfully
incorporate a realistic neutrino sector (with linear and/or inverse low scale
seesaw mechanism), which was so far a missing ingredient. Second, we
investigate in detail their compatibility with the ,
anomalies; we find that the anomalies do not have a consistent explanation
within such models. Third, we demonstrate that these models have other
compelling phenomenological features; we study the correlations between the
flavour violating processes of and - conversion in a muonic
atom, showing how a GUT imprint could manifest itself in experiments.Comment: Revised version, published in NPB. New material, general conclusions
unchanged. 30 pages, 4 figures, 2 table
Radiative Corrections to Chargino Production with Polarized Beams
We show that radiative corrections to chargino production in
electron-positron annihilation with polarized beams can be large especially in
the case of right handed electrons. In addition, there is some dependency on
the squark masses that allows us to extract information about the squark
spectrum from the chargino production.Comment: 4 pages, including 4 figures. Talk given at Linear Collider Workshop
2000--LCWS, Fermilab, Chicago, October 24-28, 200
Radiatively Corrected Chargino Pair Production at LEP2
One-loop radiative corrections to the production cross section of a pair of
light charginos in e+e- colliders are calculated within the MSSM. Top and
bottom quarks and squarks are considered in the loops, and they are
renormalized using the MS-bar scheme. If the center of mass energy is equal to
192 GeV, positive corrections typically of 10% to 15% are found when the squark
mass parameters are equal to 1 TeV.Comment: 6 pages, including 5 figures. Latex. Talk given by M.A.D. at the
International Workshop "Beyond the Standard Model: From Theory to
Experiment", 13--17 October 1997, Valencia, Spai
Invariant approach to CP in family symmetry models
We propose the use of basis invariants, valid for any choice of CP
transformation, as a powerful approach to studying specific models of CP
violation in the presence of discrete family symmetries. We illustrate the
virtues of this approach for examples based on and family
symmetries. For , we show how to elegantly obtain several known results in
the literature. In we use the invariant approach to identify how
explicit (rather than spontaneous) CP violation arises, which is geometrical in
nature, i.e. persisting for arbitrary couplings in the Lagrangian.Comment: 4 pages plus references. v2: to be published in PR
A fuller flavour treatment of N_2-dominated leptogenesis
We discuss N_2-dominated leptogenesis in the presence of flavour dependent effects that have hitherto been neglected, in particular the off-diagonal entries of the flavour coupling matrix that connects the total flavour asymmetries, distributed in different particle species, to the lepton and Higgs doublet asymmetries. We derive analytical formulae for the final asymmetry including the flavour coupling at the N_2-decay stage as well as at the stage of washout by the lightest right-handed neutrino N_1. We point out that in general part of the electron and muon asymmetries can completely escape the wash-out at the production and a total B-L asymmetry can be generated by the lightest RH neutrino wash-out yielding so called phantom leptogenesis. Taking of all these new effects into account can enhance the final asymmetry produced by the decays of the next-to-lightest RH neutrinos by orders of magnitude, opening up new interesting possibilities for N_2-dominated thermal eptogenesis. We illustrate these effects for two models which describe realistic neutrino masses and mixing based on sequential dominance
LHC Olympics
En este trabajo reproducimos la fÃsica desarrollada en los LHC Olympics, una serie de pruebas para fÃsicos teóricos en las que deben interpretar unos conjuntos de datos, llamados cajas negras, los cuales son simulaciones de los datos reales obtenidos en colisiones en el LHC. Analizamos los archivos de datos usando Microsoft Excel y aplicamos algoritmos escritos en VBA para simular diferentes técnicas de análisis. Usando las muestras proporcionadas tratamos de determinar las masas de los bosones W y Z para comprobar que los métodos de masa invariante y masa transversa funcionan correctamente. Finalmente, usamos estos métodos para determinar la masa del quark top a partir de sus productos y discutimos los resultados obtenidos
The constrained E6SSM
We discuss the predictions of a constrained version of the exceptional
supersymmetric standard model (cE6SSM), with a universal high energy soft
scalar mass, soft trilinear coupling and soft gaugino mass. The spectrum
includes a light gluino, a light wino-like neutralino and chargino pair and a
light bino-like neutralino, with other sparticle masses except the lighter stop
being much heavier. We also discuss scenarios with an extra light exotic colour
triplet of fermions and scalars and a TeV scale Z', which lead to early exotic
physics signals at the LHC.Comment: To appear in proceedings of The 2009 Europhysics Conference on High
Energy Physics, 16-22 July 2009 Krakow, Poland; 4 page
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