1,703 research outputs found
Higgs sector of the MSSM: lepton flavor violation at colliders and neutralino dark matter
We examine the prospects for the detection of Higgs mediated lepton flavor
violation at LHC and at a photon collider in the minimal supersymmetric
standard model with large lepton flavor violating mass insertions in the
sector constraining the parameter space with several experimental
bounds. We find rates probably too small to be observed at future experiments
if models have to accommodate for a neutralino relic density as measured by
WMAP and explain the anomaly: better prospects are found if these
two constraints are applied only as upper bounds. The spin-independent
neutralino-nucleon cross section in the studied constrained parameter space is
just below the present CDMS limit while gamma rates from neutralino
annihilation in the halo are strongly suppressed.Comment: 6 pages, 2 figures, Prepared for the proceedings of the workshop:
"LC09: Physics at the TeV Scale and the Dark Matter Connection",
21-24 September 2009, Perugia, Ital
Unparticle Casimir effect
In this paper we present the un-Casimir effect, namely the study of the
Casimir energy in the presence of an unparticle component in addition to the
electromagnetic field contribution. The distinctive feature of the un-Casimir
effect is a fractalization of metallic plates. This result emerges through a
new dependence of the Casimir energy on the plate separation that scales with a
continuous power controlled by the unparticle dimension. As long as the perfect
conductor approximation is valid, we find bounds on the unparticle scale that
are independent of the effective coupling constant between the scale invariant
sector and ordinary matter. We find regions of the parameter space such that
for plate distances around m and larger the un-Casimir bound wins over
the other bounds.Comment: 13 pages, 3 figures; v2: improved discussion, additional references,
v3: title slightly changed, version matching that in press on Physics Letters
Perturbative unitarity bounds for effective composite models
In this paper we present the partial wave unitarity bound in the parameter
space of dimension-5 and dimension-6 effective operators that arise in a
compositeness scenario. These are routinely used in experimental searches at
the LHC to constraint contact and gauge interactions between ordinary Standard
Model fermions and excited (composite) states of mass . After deducing the
unitarity bound for the production process of a composite neutrino, we
implement such bound and compare it with the recent experimental exclusion
curves for Run 2, the High-Luminosity and High-Energy configurations of the
LHC. Our results also applies to the searches where a generic single excited
state is produced via contact interactions. We find that the unitarity bound,
so far overlooked, is quite complelling and significant portions of the
parameter space () become excluded in addition to the standard
request .Comment: This version of the paper merges the previous version published in
Phys. Lett. B 795 (2019) 644-649
(https://doi.org/10.1016/j.physletb.2019.06.042) with the subsequent Erratum
currently in press in Physics Letters B
(https://doi.org/10.1016/j.physletb.2019.134990
Testing SUSY models of lepton flavor violation at a photon collider
The loop level lepton flavor violating signals are studied in a scenario of
low-energy, R-parity conserving, supersymmetric seesaw mechanism within the
context of a high energy photon collider. Lepton flavor violation is due to off
diagonal elements in the left s-lepton mass matrix induced by renormalization
group equations. The average slepton masses and the off
diagonal matrix elements are treated as model independent free
phenomenological parameters in order to discover regions in the parameter space
where the signal cross section may be observable. At the energies of the
option of the future high-energy linear collider the signal has
a potentially large standard model background, and therefore particular
attention is paid to the study of kinematical cuts in order to reduce the
latter at an acceptable level. We find, for the () channel,
non-negligible fractions of the parameter space () where the statistical significance ()
is .Comment: 26 pages, 12 figures, Revtex
Impact of internal bremsstrahlung on the detection of gamma-rays from neutralinos
We present a detailed study of the effect of internal bremsstrahlung photons
in the context of the minimal supersymmetric standard models and their impact
on gamma-ray dark matter annihilation searches. We find that although this
effect has to be included for the correct evaluation of fluxes of high energy
photons from neutralino annihilation, its contribution is relevant only in
models and at energies where the lines contribution is dominant over the
secondary photons. Therefore, we find that the most optimistic supersymmetric
scenarios for dark matter detection do not change significantly when including
the internal bremsstrahlung. As an example, we review the gamma-ray dark matter
detection prospects of the Draco dwarf spheroidal galaxy for the MAGIC
stereoscopic system and the CTA project. Though the flux of high energy photons
is enhanced by an order of magnitude in some regions of the parameter space,
the expected fluxes are still much below the sensitivity of the instruments.Comment: 5 pages, twocolumn format, 3 figures:3 references added, accepted as
Brief Report in PR
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