2,912 research outputs found
Electroweak and supersymmetry breaking from the Higgs discovery
We will explore the consequences on the electroweak breaking condition, the
mass of supersymmetric partners and the scale at which supersymmetry is broken,
for arbitrary values of the supersymmetric parameters tan(beta) and the stop
mixing X_t, which follow from the Higgs discovery with a mass m_H\simeq 126 GeV
at the LHC. Within the present uncertainty on the top quark mass we deduce that
radiative breaking requires tan(beta) \gtrsim 7 for maximal mixing X_t\simeq
\sqrt{6}, and tan(beta) \gtrsim 20 for small mixing X_t\lesssim 1. The scale at
which supersymmetry is broken \mathcal M can be of order the unification or
Planck scale only for large values of tan(beta) and negligible mixing X_t\simeq
0. On the other hand for maximal mixing and large values of tan(beta)
supersymmetry should break at scales as low as \mathcal M\simeq 10^5 GeV. The
uncertainty in those predictions stemming from the uncertainty in the top quark
mass, i.e. the top Yukawa coupling, is small (large) for large (small) values
of tan(beta). In fact for tan(beta)=1 the uncertainty on the value of \mathcal
M is of several orders of magnitude.Comment: 16 pages, 7 figures; v2: numerical typo corrected in codes, and 2
loop radiative corrections added. Some conclusions slightly change
GMSB with Light Stops
Gauge mediated supersymmetry breaking (GMSB) is an elegant mechanism to
transmit supersymmetry breaking from the hidden to the MSSM observable sector,
which solves the supersymmetric flavor problem. However the smallness of the
generated stop mixing requires superheavy stops to reproduce the experimental
value of the Higgs mass. Two possible ways out are: i) To extend GMSB by direct
superpotential messenger-MSSM Yukawa couplings to generate sizeable mixing,
thus reintroducing the flavor problem; ii) To extend the MSSM Higgs sector with
singlets and/or triplets providing extra tree-level corrections to the Higgs
mass. Singlets will not get any soft mass from GMSB and triplets will
contribute to the parameter which could be an issue. In this paper we
explore the second way by introducing extra supersymmetric triplets with
hypercharges , with a tree-level custodial global symmetry in the Higgs sector protecting the parameter: a
supersymmetric generalization of the Georgi-Machacek model, dubbed as
supersymmetric custodial triplet model (SCTM). The renormalization group
running from the messenger to the electroweak scale mildly breaks the custodial
symmetry. We will present realistic low-scale scenarios (with the NLSP being a
Bino-like neutralino or the right-handed stau) based on general (non-minimal)
gauge mediation and consistent with all present experimental data. Their main
features are: i) Light ( TeV) stops; ii) Exotic couplings ( and ) absent in the MSSM and proportional to the
triplets VEV, ; and, iii) A possible (measurable) universality
breaking of the Higgs couplings .Comment: 21 pages, 9 figures; v2: references adde
Radiation Damping in a Non-Abelian Strongly-Coupled Gauge Theory
We study a `dressed' or `composite' quark in strongly-coupled N=4
super-Yang-Mills (SYM), making use of the AdS/CFT correspondence. We show that
the standard string dynamics nicely captures the physics of the quark and its
surrounding quantum non-Abelian field configuration, making it possible to
derive a relativistic equation of motion that incorporates the effects of
radiation damping. From this equation one can deduce a non-standard dispersion
relation for the composite quark, as well as a Lorentz covariant formula for
its rate of radiation.Comment: 10 pages; based on talks at Quantum Theory and Symmetries 6 and the
XII Mexican Workshop of Particles and Fields
Dark Matter from the Supersymmetric Custodial Triplet Model
The Supersymmetric Custodial Triplet Model (SCTM) adds to the particle
content of the MSSM three triplet chiral superfields with hypercharge
. At the superpotential level the model respects a global symmetry only broken by the Yukawa interactions. The pattern
of vacuum expectation values of the neutral doublet and triplet scalar fields
depends on the symmetry pattern of the Higgs soft breaking masses. We study the
cases where this symmetry is maintained in the Higgs sector, and when it is
broken only by the two doublets attaining different vacuum expectation values.
In the former case, the symmetry is spontaneously broken down to the vectorial
subgroup and the parameter is protected by the custodial
symmetry. However in both situations the parameter is protected at tree
level, allowing for light triplet scalars with large vacuum expectation values.
We find that over a large range of parameter space, a light neutralino can
supply the correct relic abundance of dark matter either through resonant
s-channel triplet scalar funnels or well tempering of the Bino with the triplet
fermions. Direct detection experiments have trouble probing these model points
because the custodial symmetry suppresses the coupling of the neutralino and
the and a small Higgsino component of the neutralino suppresses the
coupling with the Higgs. Likewise the annihilation cross sections for indirect
detection lie below the Fermi-LAT upper bounds for the different channels.Comment: 26 pages, 8 figures; v2 revised comments on classification method and
indirect detection section. Results unchanged, matches PRD published versio
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