3,950 research outputs found
New HiggsBounds from LEP and the Tevatron
We review the program HiggsBounds that tests theoretical predictions of
models with arbitrary Higgs sectors against the exclusion bounds obtained from
the Higgs searches at LEP and the Tevatron. We explicitly list the bounds that
have been added after the first release of HiggsBounds.Comment: 4 pages, talk given at SUSY09, Boston, June 200
Relic density of neutralino dark matter in the MSSM with CP violation
We calculate the relic density of dark matter in the MSSM with CP violation.
We analyse various scenarios of neutralino annihilation: the cases of a bino,
bino-wino and bino-Higgsino LSP, annihilation through Higgs, as well as
sfermion coannihilation scenarios. Large phase effects are found, on the one
hand due to shifts in the masses, on the other hand due to modifications of the
couplings. Taking special care to disentangle the effects in masses and
couplings, we demonstrate that the presence of CP phases can have a significant
influence on the neutralino relic abundance. Typical variations in \Omega h^2
solely from modifications in the couplings are O(10%-100%), but can reach an
order of magnitude in some cases.Comment: 36 pages, 21 figures (low resolution). A version with high-resolution
figures can be downloaded from http://cern.ch/kraml/papers/omc
Collider Bounds on Lee-Wick Higgs Bosons
We study the constraints on the Lee-Wick Higgs sector arising from direct
collider searches. We work in an effective-field theory framework, where all of
the Lee-Wick partners are integrated out, with the sole exception of the
Lee-Wick Higgs bosons. The resulting theory is a two-Higgs doublet model where
the second doublet has wrong-sign kinetic and mass terms. We include the bounds
coming from direct Higgs searches at both LEP and Tevatron using the code
HiggsBounds, and show the currently excluded parameter space. We also analyze
the prospects of LHC Run-I, finding that with a total integrated luminosity of
5 fb and a center-of-mass energy of 7 TeV, most of the parameter space
for the SM-like CP-even Higgs will be probed.Comment: 26 pages, 5 figures, matches version published by PR
Proposal for generalised Supersymmetry Les Houches Accord for see-saw models and PDG numbering scheme
The SUSY Les Houches Accord (SLHA) 2 extended the first SLHA to include
various generalisations of the Minimal Supersymmetric Standard Model (MSSM) as
well as its simplest next-to-minimal version. Here, we propose further
extensions to it, to include the most general and well-established see-saw
descriptions (types I/II/III, inverse, and linear) in both an effective and a
simple gauged extension of the MSSM framework. In addition, we generalise the
PDG numbering scheme to reflect the properties of the particles.Comment: 44 pages. Changed titl
Model-Independent Bounds on a Light Higgs
We present up-to-date constraints on a generic Higgs parameter space. An
accurate assessment of these exclusions must take into account statistical, and
potentially signal, fluctuations in the data currently taken at the LHC. For
this, we have constructed a straightforward statistical method for making full
use of the data that is publicly available. We show that, using the expected
and observed exclusions which are quoted for each search channel, we can fully
reconstruct likelihood profiles under very reasonable and simple assumptions.
Even working with this somewhat limited information, we show that our method is
sufficiently accurate to warrant its study and advocate its use over more naive
prescriptions. Using this method, we can begin to narrow in on the remaining
viable parameter space for a Higgs-like scalar state, and to ascertain the
nature of any hints of new physics---Higgs or otherwise---appearing in the
data.Comment: 32 pages, 10 figures; v3: correction made to basis of four-derivative
operators in the effective Lagrangian, references adde
RECAST: Extending the Impact of Existing Analyses
Searches for new physics by experimental collaborations represent a
significant investment in time and resources. Often these searches are
sensitive to a broader class of models than they were originally designed to
test. We aim to extend the impact of existing searches through a technique we
call 'recasting'. After considering several examples, which illustrate the
issues and subtleties involved, we present RECAST, a framework designed to
facilitate the usage of this technique.Comment: 13 pages, 4 figure
Light neutralino dark matter in the MSSM and its implication for LHC searches for staus
It was shown in a previous study that a lightest neutralino with mass below
30 GeV was severely constrained in the minimal supersymmetric standard model
(MSSM), unless it annihilates via a light stau and thus yields the observed
dark matter abundance. In such a scenario, while the stau is the
next-to-lightest supersymmetric particle (NLSP), the charginos and the other
neutralinos as well as sleptons of the first two families are also likely to be
not too far above the mass bounds laid down by the Large Electron Positron
(LEP) collider. As the branching ratios of decays of the charginos and the
next-to-lightest neutralino into staus are rather large, one expects
significant rates of tau-rich final states in such a case. With this in view,
we investigate the same-sign ditau and tri-tau signals of this scenario at the
Large Hadron Collider (LHC) for two MSSM benchmark points corresponding to
light neutralino dark matter. The associated signal rates for these channels
are computed, for the centre-of-mass energy of 14 TeV. We find that both
channels lead to appreciable rates if the squarks and the gluino are not too
far above a TeV, thus allowing to probe scenarios with light neutralinos in the
14 TeV LHC run with 10-100 fb^{-1}.Comment: 19p, 4 Fig
Neutralino Dark Matter in BMSSM Effective Theory
We study thermal neutralino dark matter in an effective field theory
extension of the MSSM, called "Beyond the MSSM" (BMSSM) in Dine, Seiberg and
Thomas (2007). In this class of effective field theories, the field content of
the MSSM is unchanged, but the little hierarchy problem is alleviated by
allowing small corrections to the Higgs/higgsino part of the Lagrangian. We
perform parameter scans and compute the dark matter relic density. The light
Higgsino LSP scenario is modified the most; we find new regions of parameter
space compared to the standard MSSM. This involves interesting interplay
between the WMAP dark matter bounds and the LEP chargino bound. We also find
some changes for gaugino LSPs, partly due to annihilation through a Higgs
resonance, and partly due to coannihilation with light stops in models that are
ruled in by the new effective terms.Comment: 37 pages + appendi
Tuning supersymmetric models at the LHC: A comparative analysis at two-loop level
We provide a comparative study of the fine tuning amount (Delta) at the
two-loop leading log level in supersymmetric models commonly used in SUSY
searches at the LHC. These are the constrained MSSM (CMSSM), non-universal
Higgs masses models (NUHM1, NUHM2), non-universal gaugino masses model (NUGM)
and GUT related gaugino masses models (NUGMd). Two definitions of the fine
tuning are used, the first (Delta_{max}) measures maximal fine-tuning wrt
individual parameters while the second (Delta_q) adds their contribution in
"quadrature". As a direct result of two theoretical constraints (the EW minimum
conditions), fine tuning (Delta_q) emerges as a suppressing factor (effective
prior) of the averaged likelihood (under the priors), under the integral of the
global probability of measuring the data (Bayesian evidence p(D)). For each
model, there is little difference between Delta_q, Delta_{max} in the region
allowed by the data, with similar behaviour as functions of the Higgs, gluino,
stop mass or SUSY scale (m_{susy}=(m_{\tilde t_1} m_{\tilde t_2})^{1/2}) or
dark matter and g-2 constraints. The analysis has the advantage that by
replacing any of these mass scales or constraints by their latest bounds one
easily infers for each model the value of Delta_q, Delta_{max} or vice versa.
For all models, minimal fine tuning is achieved for M_{higgs} near 115 GeV with
a Delta_q\approx Delta_{max}\approx 10 to 100 depending on the model, and in
the CMSSM this is actually a global minimum. Due to a strong (
exponential) dependence of Delta on M_{higgs}, for a Higgs mass near 125 GeV,
the above values of Delta_q\approx Delta_{max} increase to between 500 and
1000. Possible corrections to these values are briefly discussed.Comment: 23 pages, 46 figures; references added; some clarifications (section
2
The decay Bs -> mu+ mu-: updated SUSY constraints and prospects
We perform a study of the impact of the recently released limits on BR(Bs ->
mu+ mu-) by LHCb and CMS on several SUSY models. We show that the obtained
constraints can be superior to those which are derived from direct searches for
SUSY particles in some scenarios, and the use of a double ratio of purely
leptonic decays involving Bs -> mu+ mu- can further strengthen such
constraints. We also discuss the experimental sensitivity and prospects for
observation of Bs -> mu+ mu- during the sqrt(s)=7 TeV run of the LHC, and its
potential implications.Comment: 30 pages, 21 figures. v2: Improved discussion of constraints from B
-> tau nu, references adde
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