5,256 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
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
SUSY parameter determination at the LHC using cross sections and kinematic edges
We study the determination of supersymmetric parameters at the LHC from a
global fit including cross sections and edges of kinematic distributions. For
illustration, we focus on a minimal supergravity scenario and discuss how well
it can be constrained at the LHC operating at 7 and 14 TeV collision energy,
respectively. We find that the inclusion of cross sections greatly improves the
accuracy of the SUSY parameter determination, and allows to reliably extract
model parameters even in the initial phase of LHC data taking with 7 TeV
collision energy and 1/fb integrated luminosity. Moreover, cross section
information may be essential to study more general scenarios, such as those
with non-universal gaugino masses, and distinguish them from minimal,
universal, models.Comment: 22 pages, 8 figure
Naturalness and Fine Tuning in the NMSSM: Implications of Early LHC Results
We study the fine tuning in the parameter space of the semi-constrained
NMSSM, where most soft Susy breaking parameters are universal at the GUT scale.
We discuss the dependence of the fine tuning on the soft Susy breaking
parameters M_1/2 and m0, and on the Higgs masses in NMSSM specific scenarios
involving large singlet-doublet Higgs mixing or dominant Higgs-to-Higgs decays.
Whereas these latter scenarios allow a priori for considerably less fine tuning
than the constrained MSSM, the early LHC results rule out a large part of the
parameter space of the semi-constrained NMSSM corresponding to low values of
the fine tuning.Comment: 19 pages, 10 figures, bounds from Susy searches with ~1/fb include
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