246 research outputs found
Towards An Accurate Calculation of the Neutralino Relic Density
We compute the neutralino relic density in the minimal supersymmetric
standard model by using exact expressions for the neutralino annihilation cross
section into all tree-level final states, including all contributions and
interference terms. We find that several final states may give comparable
contributions to the relic density, which illustrates the importance of
performing a complete calculation. We compare the exact results with those of
the usual expansion method and demonstrate a sizeable discrepancy (of more than
10%) over a significant range of the neutralino mass of up to several tens of
GeV which is caused by the presence of resonances and new final-state
thresholds. We perform several related checks and comparisons. In particular,
we find that the often employed approximate iterative procedure of computing
the neutralino freeze-out temperature gives generally very accurate results,
except when the expansion method is used near resonances and thresholds.Comment: 23 pages, 4 eps figure
Efficient reconstruction of CMSSM parameters from LHC data - A case study
We present an efficient method of reconstructing the parameters of the
Constrained MSSM from assumed future LHC data, applied both on their own right
and in combination with the cosmological determination of the relic dark matter
abundance. Focusing on the ATLAS SU3 benchmark point, we demonstrate that our
simple Gaussian approximation can recover the values of its parameters
remarkably well. We examine two popular non-informative priors and obtain very
similar results, although when we use an informative, naturalness-motivated
prior, we find some sizeable differences. We show that a further strong
improvement in reconstructing the SU3 parameters can by achieved by applying
additional information about the relic abundance at the level of WMAP accuracy,
although the expected data from Planck will have only a very limited additional
impact. Further external data may be required to break some remaining
degeneracies. We argue that the method presented here is applicable to a wide
class of low-energy effective supersymmetric models, as it does not require to
deal with purely experimental issues, eg, detector performance, and has the
additional advantages of computational efficiency. Furthermore, our approach
allows one to distinguish the effect of the model's internal structure and of
the external data on the final parameters constraints.Comment: 23 pages, 10 figures - moderate revision: includes naturalness prior.
Matches published versio
Constraints on a mixed inflaton and curvaton scenario for the generation of the curvature perturbation
We consider a supersymmetric grand unified model which naturally solves the
strong CP and mu problems via a Peccei-Quinn symmetry and leads to the standard
realization of hybrid inflation. We show that the Peccei-Quinn field of this
model can act as curvaton. In contrast to the standard curvaton hypothesis,
both the inflaton and the curvaton contribute to the total curvature
perturbation. The model predicts an isocurvature perturbation too which has
mixed correlation with the adiabatic one. The cold dark matter of the universe
is mostly constituted by axions plus a small amount of lightest sparticles. The
predictions of the model are confronted with the Wilkinson microwave anisotropy
probe and other cosmic microwave background radiation data. We analyze two
representative choices of parameters and derive bounds on the curvaton
contribution to the adiabatic perturbation. We find that, for the choice which
provides the best fitting of the data, the curvaton contribution to the
adiabatic amplitude must be smaller than about 67% (at 95% confidence level).
The best-fit power spectra are dominated by the adiabatic part of the inflaton
contribution. We use Bayesian model comparison to show that this choice of
parameters is disfavored with respect to the pure inflaton scale-invariant case
with odds of 50 to 1. For the second choice of parameters, the adiabatic mode
is dominated by the curvaton, but this choice is strongly disfavored relative
to the pure inflaton scale-invariant case (with odds of 10^7 to 1). We conclude
that in the present framework the perturbations must be dominated by the
adiabatic component from the inflaton.Comment: 27 pages including 16 figures, uses Revte
New Cosmological and Experimental Constraints on the CMSSM
We analyze the implications of several recent cosmological and experimental
measurements for the mass spectra of the Constrained MSSM (CMSSM). We compute
the relic abundance of the neutralino and compare the new cosmologically
expected and excluded mass ranges with those ruled out by the final LEP bounds
on the lightest chargino and Higgs masses, with those excluded by current
experimental values of \br(B\to X_s \gamma), and with those favored by the
recent measurement of the anomalous magnetic moment of the muon. We find that
for tan\beta\lsim 45 there remains relatively little room for the mass
spectra to be consistent with the interplay of the several constraints. On the
other hand, at larger values of \tev$ range.Comment: LaTex, 21 pages, 4 PS figures. Version published in JHEP, for updates
see hep-ph/020617
MSSM Forecast for the LHC
We perform a forecast of the MSSM with universal soft terms (CMSSM) for the
LHC, based on an improved Bayesian analysis. We do not incorporate ad hoc
measures of the fine-tuning to penalize unnatural possibilities: such
penalization arises from the Bayesian analysis itself when the experimental
value of is considered. This allows to scan the whole parameter space,
allowing arbitrarily large soft terms. Still the low-energy region is
statistically favoured (even before including dark matter or g-2 constraints).
Contrary to other studies, the results are almost unaffected by changing the
upper limits taken for the soft terms. The results are also remarkable stable
when using flat or logarithmic priors, a fact that arises from the larger
statistical weight of the low-energy region in both cases. Then we incorporate
all the important experimental constrains to the analysis, obtaining a map of
the probability density of the MSSM parameter space, i.e. the forecast of the
MSSM. Since not all the experimental information is equally robust, we perform
separate analyses depending on the group of observables used. When only the
most robust ones are used, the favoured region of the parameter space contains
a significant portion outside the LHC reach. This effect gets reinforced if the
Higgs mass is not close to its present experimental limit and persits when dark
matter constraints are included. Only when the g-2 constraint (based on
data) is considered, the preferred region (for ) is well inside
the LHC scope. We also perform a Bayesian comparison of the positive- and
negative- possibilities.Comment: 42 pages: added figures and reference
The health of SUSY after the Higgs discovery and the XENON100 data
We analyze the implications for the status and prospects of supersymmetry of
the Higgs discovery and the last XENON data. We focus mainly, but not only, on
the CMSSM and NUHM models. Using a Bayesian approach we determine the
distribution of probability in the parameter space of these scenarios. This
shows that, most probably, they are now beyond the LHC reach . This negative
chances increase further (at more than 95% c.l.) if one includes dark matter
constraints in the analysis, in particular the last XENON100 data. However, the
models would be probed completely by XENON1T. The mass of the LSP neutralino
gets essentially fixed around 1 TeV. We do not incorporate ad hoc measures of
the fine-tuning to penalize unnatural possibilities: such penalization arises
automatically from the careful Bayesian analysis itself, and allows to scan the
whole parameter space. In this way, we can explain and resolve the apparent
discrepancies between the previous results in the literature. Although SUSY has
become hard to detect at LHC, this does not necessarily mean that is very
fine-tuned. We use Bayesian techniques to show the experimental Higgs mass is
at off the CMSSM or NUHM expectation. This is substantial but
not dramatic. Although the CMSSM or the NUHM are unlikely to show up at the
LHC, they are still interesting and plausible models after the Higgs
observation; and, if they are true, the chances of discovering them in future
dark matter experiments are quite high
Is there anyone beyond capitalist social relations and abstract rights? Analysing the IACtHR innovative jurisprudence regarding collective (cultural) rights and its transformative potential.
This research explores the transformative role of the Global South in innovative jurisprudence concerning (cultural) collective rights, transcending its conventional perception as a mere recipient of legal norms. Focusing on the Inter-American Court of Human Rights (IACtHR), the study investigates the impact of landmark cases worldwide and their potential challenges to the (neo)liberal capitalist system. Through an analysis and categorization of judgments, the research reveals that although the IACtHR has recognized collective rights through innovative interpretations, it falls short of posing a significant challenge to private property and capitalism. Additionally, it emphasizes the need for a collective and concrete vision of rights to achieve meaningful transformation. The study also finds a potential alliance among peripheral regions to foster innovative jurisprudence through court dialogue, which may lead to a more substantial transformational role in safeguarding collective rights
Curvaton Dynamics
In contrast to the inflaton's case, the curvature perturbations due to the
curvaton field depend strongly on the evolution of the curvaton before its
decay. We study in detail the dynamics of the curvaton evolution during and
after inflation. We consider that the flatness of the curvaton potential may be
affected by supergravity corrections, which introduce an effective mass
proportional to the Hubble parameter. We also consider that the curvaton
potential may be dominated by a quartic or by a non-renormalizable term. We
find analytic solutions for the curvaton's evolution for all these
possibilities. In particular, we show that, in all the above cases, the
curvaton's density ratio with respect to the background density of the Universe
decreases. Therefore, it is necessary that the curvaton decays only after its
potential becomes dominated by the quadratic term, which results in (Hubble
damped) sinusoidal oscillations. In the case when a non-renormalizable term
dominates the potential, we find a possible non-oscillatory attractor solution
that threatens to erase the curvature perturbation spectrum. Finally, we study
the effects of thermal corrections to the curvaton's potential and show that,
if they ever dominate the effective mass, they lead to premature thermalization
of the curvaton condensate. To avoid this danger, a stringent bound has to be
imposed on the coupling of the curvaton to the thermal bath.Comment: 24 pages, 3 Postscript figures, RevTe
The case for 100 GeV bino dark matter: A dedicated LHC tri-lepton search
Global fit studies performed in the pMSSM and the photon excess signal
originating from the Galactic Center seem to suggest compressed electroweak
supersymmetric spectra with a 100 GeV bino-like dark matter particle. We
find that these scenarios are not probed by traditional electroweak
supersymmetry searches at the LHC. We propose to extend the ATLAS and CMS
electroweak supersymmetry searches with an improved strategy for bino-like dark
matter, focusing on chargino plus next-to-lightest neutralino production, with
a subsequent decay into a tri-lepton final state. We explore the sensitivity
for pMSSM scenarios with
GeV in the TeV run of the LHC. Counterintuitively, we find that
the requirement of low missing transverse energy increases the sensitivity
compared to the current ATLAS and CMS searches. With 300 fb of data we
expect the LHC experiments to be able to discover these supersymmetric spectra
with mass gaps down to GeV for DM masses between 40 and 140
GeV. We stress the importance of a dedicated search strategy that targets
precisely these favored pMSSM spectra.Comment: Published in JHE
Dark Matter, Sparticle Spectroscopy and Muon in
We explore the sparticle mass spectra including LSP dark matter within the
framework of supersymmetric (422)
models, taking into account the constraints from extensive LHC and cold dark
matter searches. The soft supersymmetry-breaking parameters at can be
non-universal, but consistent with the 422 symmetry. We identify a variety of
coannihilation scenarios compatible with LSP dark matter, and study the
implications for future supersymmetry searches and the ongoing muon g-2
experiment.Comment: 21 pages, 8 fig
- …