3,374 research outputs found
The specificity of searches for , and coming from extra dimensions
We discuss the specificity of searches for hypothetical ,
and bosons at hadron colliders in single top
quark and production and Drell-Yan processes assuming these
particles to be the Kaluza-Klein excitations of the gauge bosons of the
Standard Model. In this case any process mediated by is also mediated by
the whole KK tower of its excitations, whereas to the processes mediated by
and there is not only a contribution from their KK towers, but also
from that of the graviton. The contributions of the towers above ,
and and above the first excitation of the
graviton are included with the help of effective four-fermion Lagrangians. We
compute the cross-sections of these processes taking into account the
contributions of the Standard Model gauge bosons, of their first KK modes and
of the corresponding KK towers and discuss the impact of the interference
between them. For pp-collisions at the LHC with the center of mass energy 14
TeV we found specific changes of the distribution tails due to the interference
effects. Such a modification of distribution tails is characteristic for the
processes mediated by particles coming from extra dimensions and should always
be taken into account when looking for them.Comment: 14 pages, 12 figures, LaTeX. References added, figures added, text
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CompHEP 4.4 - Automatic Computations from Lagrangians to Events
We present a new version of the CompHEP program (version 4.4). We describe
shortly new issues implemented in this version, namely, simplification of quark
flavor combinatorics for the evaluation of hadronic processes, Les Houches
Accord based CompHEP-PYTHIA interface, processing the color configurations of
events, implementation of MSSM, symbolical and numerical batch modes, etc. We
discuss how the CompHEP program is used for preparing event generators for
various physical processes. We mention a few concrete physics examples for
CompHEP based generators prepared for the LHC and Tevatron.Comment: The paper has been presented on IX International Workshop on Advanced
Computing and Analysis Techniques in Physics Research December 1-5, 2003.
KEK, Japan. 10 pages, 2 figure
Prospects for Dark Matter Search at the Super c-tau Factory
We present perspectives for searching for light dark matter production
mediated by a leptophilic scalar {\phi} and a dark photon A' in in experiments
at the Super c-tau Factory. Based on the analysis of the associative production
of mediators and {\tau} -leptons at the energies of the future collider, the
possibility of searching in the non-excluded region of the parameter space was
found. The obtained sensitivity curves at the 90% C.L. for the mediators mass
range below 4 GeV demonstrate the power of the SCTF for light dark matter
search.Comment: 6 pages, 7 figure
Prospects of mass measurements for neutral MSSM Higgs bosons in the intense-coupling regime at a Linear Collider
We analyze the prospects for detecting the three neutral Higgs bosons of the
Minimal Supersymmetric extension of the Standard Model in the intense-coupling
regime at e+e- colliders. Due to the small mass differences between the Higgs
states in this regime and their relative large total decay widths, the
discrimination between the particles is challenging at the LHC and in some
cases even impossible. We propose to use the missing mass technique in the
Higgs-strahlung process in e+e- collisions to distinguish between the two
CP-even Higgs eigenstates h and H, relying on their b b-bar decay in the
b,b-bar,l+,l- event sample. Ah and AH associated production is then studied in
the 4b-jet event sample to probe the CP-odd A boson. At collider energies
sqrt(s) = 300 GeV and an integrated luminosity of 500 fb-1, accuracies in the
mass measurement of the CP-even Higgs bosons are expected to range from 100 to
300 MeV, while for the CP-odd A boson, accuracies of less than 500 MeV can be
obtained.Comment: 12 pages, 15 Postscript figure
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