5,098 research outputs found
The search for new physics by the measurement of the 4-jet cross section at LHC and FNAL
We investigate the possibility to look for new physics by the measurement of
the 4-jet cross section at LHC and FNAL. In particular, we consider the model
with scalar colour octet and the supersymmetric model with R-parity violation.
In both models pair produced new particles decay into 2 jets thus leading to
4-jet events. Therefore, the measurement of the distributions of 4-jet
differential cross section on the invariant dijet masses allows to look for new
physics. The main background comes from standard QCD 4-jet events. We find that
at LHC it would be possible to discover scalar colour particles with masses up
to 900 Gev and for FNAL the corresponding bound is 175 Gev.Comment: 14 pages, late
Hyperfast Interstellar Travel in General Relativity
The problem is discussed of whether a traveller can reach a remote object and
return back sooner than a photon would when taken into account that the
traveller can partly control the geometry of his world. It is argued that under
some reasonable assumptions in globally hyperbolic spacetimes the traveller
cannot hasten reaching the destination. Nevertheless, it is perhaps possible
for him to make an arbitrarily long round-trip within an arbitrarily short
(from the point of view of a terrestrial observer) time.Comment: The final version, close to (but better than) what will be published
in Phys. Rev. D. The explanatory part is made more detaile
Uncertainties and Discovery Potential in Planned Experiments
We describe a method for estimation of the discovery potential on new physics
in planned experiments. The effective significance of signal for given
probability of observation is proposed for planned experiments instead of the
usual significances S_1 = n_s/sqrt{n_b} and S_2 = n_s/sqrt{n_s+n_b}, where n_s
and n_b are the average numbers of signal and background events. Application of
the test of equal-probability allows to estimate the exclusion limits on new
physics. We also estimate the influence of systematic uncertainty related to
nonexact knowledge of signal and background cross sections on the discovery
probability of new physics in planned experiments. An account of such
systematics is very essential in the search for supersymmetry at LHC.Comment: 30 pages (1 LaTeX file), 14 eps files (figures), Talk presented by
S.I.Bityukov at the Advanced Statistical Techniques in Particle Physics,
March 18-22, 2002, Durham, U
LHC(CMS) SUSY discovery potential for the case of nonuniversal gaugino masses
We investigate squark and gluino pair production at LHC(CMS) for the case of
nonuniversal gaugino masses. Visibility of signal by an excess over SM
background in events depends
rather strongly on the relation between LSP, gluino and squark masses and it
decreases with the increase of LSP mass. For relatively heavy LSP mass close to
squark or gluino masses it is possible to detect SUSY for TeV.}Comment: 1 latex (3 pages), 2 eps (figures) files. Presented by N.V.Krasnikov
at the 9th International Conference on Supersymmetries in Physics (SUSY 01),
11-17 Jun 2001, Dubna, Russi
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