572 research outputs found
Could we learn more about HERA high anomaly from LEP200 and TEVATRON? R-parity violation scenario
The excess of high events at HERA reported in the early 1997 by H1 and
ZEUS collaborations has become the subject of extensive studies in the
framework of several models related to new physics. Here we concentrate on the
most promising, from our point of view, model describing HERA anomaly. We
update our previous analysis and take into account new HERA statistics of the
1997 year. HERA events are considered within the R-parity broken SUSY model for
a specific scenario with several non-zero couplings. R-parity broken SUSY with
several non-zero couplings could explain both high and observed at HERA. The consequence of such a particular scenario is the
excess of high di- or tri-jet events at HERA. The relation of this
scenario for LEP and TEVATRON colliders is considered. This study shows that if
a squark resonance does take place at HERA, supersymmetry with broken R-parity
can be revealed at either LEP200 or TEVATRON in the near future.Comment: 15 pages, LaTeX file with 9 eps figure
IS (Low Energy) SUSY STILL ALIVE?
Supersymmetry, a new symmetry that relates bosons and fermions in particle
physics, still escapes observation. Search for supersymmetry is one of the main
aims of the Large Hadron Collider. The other possible manifestation of
supersymmetry is the Dark Matter in the Universe. The present lectures contain
a brief introduction to supersymmetry in particle physics. The main notions of
supersymmetry are introduced. The supersymmetric extension of the Standard
Model -- the Minimal Supersymmetric Standard Model -- is considered in more
detail. Phenomenological features of the Minimal Supersymmetric Standard Model
as well as possible experimental signatures of supersymmetry at the Large
Hadron Collider are described. The present limits on supersymmetric particles
are presented and the allowed region of parameter space of the MSSM is shown.Comment: 59 pages, 35 figures, PDFLatex, Lectures at the European School of
High-Energy Physics, June 2012, Anjou, Franc
Minimal Supersymmetric Standard Model within CompHEP software package
The Minimal Supersymmetric Standard Model is presented as a model for the
CompHEP software package as a set of files containing the complete Lagrangian
of the MSSM, particle contents and parameters. All resources of CompHEP with a
user-friendly interface are now available for the phenomenological study of the
MSSM. Various special features of the model are discussed.Comment: 11 pages, LaTeX, submitted to Comp. Phys. Communicatio
Renormalization Group Improved Radiative Corrections to the Supersymmetric Higgs Boson Masses
The one-loop radiative corrections to the Higgs boson potential in the MSSM,
originating from the top quark and squark loops, are summed in the leading log
approximation using the renormalization group. The RG improved effective
potential is minimized and the corrections to the CP-odd and CP-even Higgs
boson masses are calculated. The resulting masses exhibit smoother top mass
dependence than those calculated without RG summation. We have also found that
for preferable values of the top mass the light Higgs mass does not exceed 100
GeV.Comment: 10 PAGES, 1 FIGURE ENCLOSED, LATE
Long-lived Charginos in the Focus-point Region of the MSSM Parameter Space
We analyse the possibility to get light long-lived charginos within the
framework of the MSSM with gravity mediated SUSY breaking. We find out that
this possibility can be realized in the so-called focus-point region of
parameter space. The mass degeneracy of higgsino-like chargino and two
higgsino-like neutralinos is the necessary condition for a long lifetime. It
requires the fine-tuning of parameters, but being a single additional
constraint in the whole parameter space it can be fulfilled in the Constrained
MSSM along the border line where radiative electroweak symmetry breaking fails.
In a narrow band close to the border line the charginos are long-lived
particles. The cross-sections of their production and co-production at the LHC
via electroweak interaction reach a few tenth of pb.Comment: LaTeX, 11 pages, 11 eps figure
Production of Long-Lived Sleptons at LHC
We analyse the MSSM parameter space and discuss the narrow band near the
so-called co-annihilation region where sleptons may be long-lived particles.
This region is consistent with the WMAP restrictions on the Dark matter and
depends on the value of . In this region staus are long-lived and
may go through the detector. Due to a relatively small mass (150 850
GeV) their production cross-section at LHC may reach a few % pb.Comment: LaTex, 8 pages, 6 eps figure
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