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

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 $(n \geq 2)jets + E^{miss}_T + (m \geq leptons)$ 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 $(m_{\tilde{q}}, m_{\tilde{g}}) \leq (1 - 1.5)$ 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

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