86 research outputs found
MSSM: Cornered and Correlated
Inspired by the latest results of ATLAS and CMS on the search for the
standard model (SM) Higgs scalar, we discuss in this article the correlations
between Higgs-boson properties, low-energy observables, such as B -> X_sgamma,
B_s -> mu^+mu^-, and (g-2)_mu, and the dark matter (DM) relic density. We focus
on the corners of the MSSM parameter space where the pp -> h -> gammagamma
signal is enhanced due to the presence of a light stau state. In this region
tan(beta), M_A, A_t, and mu take large values, and we find striking
correlations between many of the considered observables. In particular, the B
-> X_sgamma branching fraction is enhanced, while the B_s -> mu^+mu^- rate
tends to be below the SM expectation. In contrast, the Higgs-boson couplings
show good overall agreement with the preliminary experimental determinations,
the DM abundance is consistent with observation, and the discrepancy in
(g-2)_mu is reduced. The predicted deviations and found correlations could be
tested in the near future and hence may become very valuable as guidelines and
consistency checks.Comment: 27 pages, 5 figure
Higgs Production in Neutralino Decays in the MSSM - The LHC and a Future e+e- Collider
The search for the production of weakly-interacting SUSY particles at the LHC
is crucial for testing supersymmetry in relation to dark matter. Decays of
neutralinos into Higgs bosons occur over some significant part of the SUSY
parameter space and represent the most important source of boson production
in SUSY decay chains in the MSSM. We study h production in neutralino decays
using scans of the phenomenological MSSM. Whilst in constrained MSSM scenarios
the decay chi^0_2 -> h chi^0_1 is the dominant channel, this does not hold in
more general MSSM scenarios. On the other hand, the chi^0_2,3 -> h chi^0_1
decays remain important and are highly complementary to multi-lepton final
states in the LHC searches. The perspectives for the LHC analyses at 8 and 14
TeV as well as the reach of an e+e- collider at 0.5, 1, 1.5 and 3 TeV are
discussed.Comment: 11 pages, 13 figure
Supersymmetry with Light Dark Matter confronting the recent CDMS and LHC Results
We revisit MSSM scenarios with light neutralino as a dark matter candidate in
view of the latest LHC and dark matter direct and indirect detection
experiments. We show that scenarios with a very light neutralino (~ 10 GeV) and
a scalar bottom quark close in mass, can satisfy all the available constraints
from LEP, Tevatron, LHC, flavour and low energy experiments and provide
solutions in agreement with the bulk of dark matter direct detection
experiments, and in particular with the recent CDMS results.Comment: v2: 11 pages, 9 figures; extended study of mono-jet constraints,
revised references. Two benchmark SLHA files provide
Flavor Data Constraints on the SUSY Parameter Space
We present an overview of the indirect constraints from flavor physics on
supersymmetric models. During the past few years flavor data, and in particular
b -> s gamma transitions, have been extensively used in order to constrain
supersymmetric parameter spaces. We will briefly illustrate here the
constraints obtained by a collection of low energy observables including FCNC
transitions, rare decays, leptonic and semileptonic decays of B mesons, as well
as leptonic decays of K mesons. The theoretical predictions can be obtained
using the computer program SuperIso.Comment: Invited talk at the 16th International Conference on Supersymmetry
and the Unification of Fundamental Interactions (SUSY08), Seoul, Korea, June
16-21, 200
The correlation matrix of Higgs rates at the LHC
The imperfect knowledge of the Higgs boson decay rates and cross sections at
the LHC constitutes a critical systematic uncertainty in the study of the Higgs
boson properties. We show that the full covariance matrix between the Higgs
rates can be determined from the most elementary sources of uncertainty by a
direct application of probability theory. We evaluate the error magnitudes and
full correlation matrix on the set of Higgs cross sections and branching ratios
at , , and TeV, which are provided in ancillary files.
The impact of this correlation matrix on the global fits is illustrated with
the latest + TeV Higgs dataset.Comment: 25 pages, 1 figure. Complete covariance matrix is available in C,
Fortran, Mathematica, PDF, TeX and text formats in ancillary file
One-loop quantum corrections to cosmological scalar field potentials
We study the loop corrections to potentials of complex or coupled real scalar
fields used in cosmology to account for dark energy, dark matter or dark fluid.
We show that the SUGRA quintessence and dark matter scalar field potentials are
stable against the quantum fluctuations, and we propose solutions to the
instability of the potentials of coupled quintessence and dark fluid scalar
fields. We also find that a coupling to fermions is very restricted, unless
this coupling has a structure which already exists in the scalar field
potential or which can be compensated by higher order corrections. Finally, we
study the influence of the curvature and kinetic term corrections.Comment: 11 pages, 1 figure, accepted for publication in Phys. Rev.
Supersymmetric Heavy Higgs Bosons at the LHC
The search for heavy Higgs bosons is an essential step in the exploration of
the Higgs sector and in probing the Supersymmetric parameter space. This paper
discusses the constraints on the M(A) and tan beta parameters derived from the
bounds on the different decay channels of the neutral H and A bosons accessible
at the LHC, in the framework of the phenomenological MSSM. The implications
from the present LHC results and the expected sensitivity of the 14 TeV data
are discussed in terms of the coverage of the [M(A) - tan beta] plane. New
channels becoming important at 13 and 14 TeV for low values of tan beta are
characterised in terms of their kinematics and the reconstruction strategies.
The effect of QCD systematics, SUSY loop effects and decays into pairs of SUSY
particles on these constraints are discussed in details.Comment: 12 pages, 18 figure
An MCMC study of general squark flavour mixing in the MSSM
We present an extensive study of non-minimally flavour violating (NMFV) terms
in the Lagrangian of the Minimal Supersymmetric Standard Model (MSSM). We
impose a variety of theoretical and experimental constraints and perform a
detailed scan of the parameter space by means of a Markov Chain Monte-Carlo
(MCMC) setup. This represents the first study of several non-zero
flavour-violating elements within the MSSM. We present the results of the MCMC
scan with a special focus on the flavour-violating parameters. Based on these
results, we define benchmark scenarios for future studies of NMFV effects at
the LHC.Comment: 8 pages, 3 figures. To appear in the proceedings of the European
Physical Society Conference on High Energy Physics 2015 (EPS-HEP 2015),
Vienna, Austria, 22nd to 29th of July 201
A model-independent analysis of transitions with GAMBIT âs FlavBit
The search for flavour-changing neutral current effects in B-meson decays is a powerful probe of physics beyond the Standard Model. Deviations from SM behaviour are often quantified by extracting the preferred values of the Wilson coefficients of an operator product expansion. We use the FlavBit module of the GAMBIT package to perform a simultaneous global fit of the Wilson coefficients C7, C9, and C10 using a combination of all current data on bâsÎŒ+ÎŒâ transitions. We further extend previous analyses by accounting for the correlated theoretical uncertainties at each point in the Wilson coefficient parameter space, rather than deriving the uncertainties from a Standard Model calculation. We find that the best fit deviates from the SM value with a significance of 6.6Ï. The largest deviation is associated with a vector coupling of muons to b and s quarks
Collider constraints on electroweakinos in the presence of a light gravitino
Using the GAMBIT global fitting framework, we constrain the MSSM with an eV-scale gravitino as the lightest supersymmetric particle, and the six electroweakinos (neutralinos and charginos) as the only other light new states. We combine 15 ATLAS and 12 CMS searches at 13 TeV, along with a large collection of ATLAS and CMS measurements of Standard Model signatures. This model, which we refer to as the G~-EWMSSM, exhibits quite varied collider phenomenology due to its many permitted electroweakino production processes and decay modes. Characteristic G~-EWMSSM signal events have two or more Standard Model bosons and missing energy due to the escaping gravitinos. While much of the G~-EWMSSM parameter space is excluded, we find several viable parameter regions that predict phenomenologically rich scenarios with multiple neutralinos and charginos within the kinematic reach of the LHC during Run 3, or the High Luminosity LHC. In particular, we identify scenarios with Higgsino-dominated electroweakinos as light as 140 GeV that are consistent with our combined set of collider searches and measurements. The full set of G~-EWMSSM parameter samples and GAMBIT input files generated for this work is available via Zenodo
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