340 research outputs found
Top-Down Approach to Unified Supergravity Models
We introduce a new approach for studying unified supergravity models. In this
approach all the parameters of the grand unified theory (GUT) are fixed by
imposing the corresponding number of low energy observables. This determines
the remaining particle spectrum whose dependence on the low energy observables
can now be investigated. We also include some SUSY threshold corrections that
have previously been neglected. In particular the SUSY threshold corrections to
the fermion masses can have a significant impact on the Yukawa coupling
unification.Comment: 19 pages, uuencoded compressed ps file, DESY 94-057 (paper format
corrected
Production of neutral MSSM Higgs bosons in collisions: a complete 1-loop calculation
We present the first complete 1-loop diagrammatic calculation of the cross
sections for the neutral Higgs production processes e^+e^-\ra Z^0h^0 and
e^+e^-\ra A^0h^0 in the minimal supersymmetric standard model. We compare the
results from the diagrammatic calculation with the corresponding ones of the
simpler and compact effective potential approximation and discuss the typical
size of the differences.Comment: LaTeX, 16 pages, 8 figures appended in a uuencoded file, complete
PostScript file available at
http://itpaxp1.physik.uni-karlsruhe.de/prep/KA-TP-16-1995/KA-TP-16-199
The decay : a complete 1-loop calculation in the MSSM
In the minimal supersymmetric standard model the decay of
the light neutral scalar is kinematically allowed for low values of
when radiative corrections to the neutral Higgs masses are taken
into account. The width of this decay mode is revisited on the basis of a
complete 1-loop diagrammatic calculation. We give the analytical expressions
and numerical results and compare them with the corresponding ones from the
simpler and compact approximations of the effective potential method and the
renormalization group approach.Comment: 25 pages, LaTex, 10 figures included. Complete ps-file also available
via WWW at http://itpaxp1.physik.uni-karlsruhe.de/prep/prep.htm
MSSM Higgs Boson Phenomenology at the Tevatron Collider
The Higgs sector of the minimal supersymmetric standard model (MSSM) consists
of five physical Higgs bosons, which offer a variety of channels for their
experimental search. The present study aims to further our understanding of the
Tevatron reach for MSSM Higgs bosons, addressing relevant theoretical issues
related to the SUSY parameter space, with special emphasis on the radiative
corrections to the down--quark and lepton couplings to the Higgs bosons for
large . We performed a computation of the signal and backgrounds for
the production processes and at the upgraded Tevatron,
with being the neutral MSSM Higgs bosons. Detailed experimental
information and further higher order calculations are demanded to
confirm/refine these predictions.Comment: 47 pages, REVTex format, 15 figures; spacing changed to reduce
length, references added or moved within manuscript for clarity, some
rewording, labelling corrected on two figures, results unchange
Electroweak Precision Observables in the MSSM with Non-Minimal Flavor Violation
The leading corrections to electroweak precision observables in the MSSM with
non-minimal flavor violation (NMFV) are calculated and the effects on M_W and
sin^2 theta_eff are analyzed. The corrections are obtained by evaluating the
full one-loop contributions from the third and second generation scalar quarks,
including the mixing in the scalar top and charm, as well as in the scalar
bottom and strange sector. Furthermore the leading corrections to the mass of
the lightest MSSM Higgs boson, m_h, is obtained. The electroweak one-loop
contribution to M_W can amount up to 140 MeV and up to 70x10^{-5} for sin^2
theta_eff, allowing to set limits on the NMFV parameters. The corrections for
m_h are not significant for moderate generation mixing.Comment: LaTeX, 21 pages, 8 figures. Complete one-loop effects from scalar
quark generation mixing (beyond Delta rho) included for M_W and sin^2
theta_ef
Possible Gauge Theoretic Origin for Quark-Lepton Complementarity
Similarity between the weak interaction properties of quarks and leptons has
led to suggestions that the origin of lepton mixing angles may be related to
those of quarks. In this paper, we present a gauge model based on group that leads to a new form for the quark
lepton complementarity which predicts the solar neutrino mixing angle in terms
of the Cabibbo angle for the case of inverted mass hierarchy for neutrinos. We
also indicate how these ideas can be implemented in an inspired
trinification model, which is more
closely allied to string theory by the AdS/CFT correspondence.Comment: 9 pages, latex, no figures; presentation improved; results unchanged;
minor typos correcte
Hadronic production of bottom-squark pairs with electroweak contributions
We present the complete computation of the tree-level and the next-to-leading
order electroweak contributions to bottom-squark pair production at the LHC.
The computation is performed within the minimal supersymmetric extension of the
Standard Model. We discuss the numerical impact of these contributions in
several supersymmetric scenarios.Comment: 33 pages, v2: preprint numbers correcte
FACT - Monitoring Blazars at Very High Energies
The First G-APD Cherenkov Telescope (FACT) was built on the Canary Island of
La Palma in October 2011 as a proof of principle for silicon based photosensors
in Cherenkov Astronomy. The scientific goal of the project is to study the
variability of active galatic nuclei (AGN) at TeV energies. Observing a small
sample of TeV blazars whenever possible, an unbiased data sample is collected.
This allows to study the variability of the selected objects on timescales from
hours to years. Results from the first three years of monitoring will be
presented. To provide quick flare alerts to the community and trigger
multi-wavelength observations, a quick look analysis has been installed on-site
providing results publicly online within the same night. In summer 2014,
several flare alerts were issued. Results of the quick look analysis are
summarized.Comment: 2014 Fermi Symposium proceedings - eConf C14102.
Data compression for the First G-APD Cherenkov Telescope
The First Geiger-mode Avalanche photodiode (G-APD) Cherenkov Telescope (FACT)
has been operating on the Canary island of La Palma since October 2011.
Operations were automated so that the system can be operated remotely. Manual
interaction is required only when the observation schedule is modified due to
weather conditions or in case of unexpected events such as a mechanical
failure. Automatic operations enabled high data taking efficiency, which
resulted in up to two terabytes of FITS files being recorded nightly and
transferred from La Palma to the FACT archive at ISDC in Switzerland. Since
long term storage of hundreds of terabytes of observations data is costly, data
compression is mandatory. This paper discusses the design choices that were
made to increase the compression ratio and speed of writing of the data with
respect to existing compression algorithms.
Following a more detailed motivation, the FACT compression algorithm along
with the associated I/O layer is discussed. Eventually, the performances of the
algorithm is compared to other approaches.Comment: 17 pages, accepted to Astronomy and Computing special issue on
astronomical file format
Improved full one--loop corrections to A^0 -> \sq_1 \sq_2 and \sq_2 -> \sq_1 A^0
We calculate the full electroweak one-loop corrections to the decay of the
CP-odd Higgs boson A^0 into scalar quarks in the minimal supersymmetric
extension of the Standard Model (MSSM). Due to the complex structure of the
electroweak sector a proper renormalization of many parameters in the on-shell
renormalization scheme is necessary. For the decay into sbottom quarks,
especially for large tanb, the corrections can be very large in the on-shell
renormalization scheme, which makes the perturbation series unreliable. We
solve this problem by an appropriate definition of the tree-level coupling in
terms of running quark masses and running trilinear couplings A_q. We also
discuss the decay of heavy scalar quarks into light scalar quarks and A^0. We
find that the corrections are significant and therefore cannot be neglected.Comment: 15 pages, 9 figures, Fig. 8 correcte
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