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N. Stepanov

Publications and source records attributed to N. Stepanov.

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Prospects of Detecting Massive Charged Higgs from Hadronic Decay H -> tb in CMS

The possibility to detect the massive charged Higgs boson H using the hadronic decay channel H -> tb in the associated production pp -> tH + X in the CMS experiment at LHC is studied. There is a large background from ttbb events which makes the observation difficult. Detection of a Higgs signal in this channel requires an excellent b-tagging performance. Good calorimeter mass resolution is also necessary for the full event reconstruction.

hep-ph

Summary of the CMS Discovery Potential for the MSSM SUSY Higgses

This work summarises the present understanding of the expected MSSM SUSY Higgs reach for CMS. Many of the studies presented here result from detailed detector simulations incorporating final CMS detector design and response. With 30 fb-1 the h -> gamma,gamma and h -> bb channels allow to cover most of the MSSM parameter space. For the massive A,H,H+ MSSM Higgs states the channels A,H -> tau,tau and H+ -> tau,nu turn out to be the most profitable ones in terms of mass reach and parameter space coverage. Consequently CMS has made a big effort to trigger efficiently on taus. Provided neutralinos and sleptons are not too heavy, there is an interesting complementarity in the reaches for A,H -> tau,tau and A,H -> chi,chi.

hep-ph

Bottom Production

We review the prospects for bottom production physics at the LHC.

hep-ph

Muon Track Matching

For most physical processes the tracks observed in the muon stations must be matched with the corresponding tracks in the inner tracker, the external muon system providing muon identification and triggering but the tracker points giving the precise momentum measurement at lower momenta. For high momenta the momentum resolution is much improved by the interconnection of inner and outer measurements. The matching of outer and inner measurements is more delicate in case of muons embedded in jets. A study of the matching procedure was carried out using samples of (b, anti b) jets at high Pt, requiring (b, anti b) -> mu decays.

hep-ex

Observability of B_(d)s-> mu mu decay with the CMS detector

We have updated our previous study on the possibility to observe the rare B0_s -> 2mu decay with detailed simulation of the TDR version of the CMS detector. The full simulation and reconstruction procedure has been done both for the signal and background. We improved our previous results on expected sensitivity using more sophisticated algorithms for the track and vertex reconstruction and tighter selection criteria.

hep-ph

Higgs Boson Discovery Potential of LHC in the Channel $pp \toγγ+jet$

We discuss the SM Higgs discovery potential of LHC in the reaction $pp\to H+ jet\toγγ+jet$ when the jet is observed at sufficiently high $E_t$ to be reliably identified. We conclude that this channel gives promising discovery possibilities for the Higgs boson mass range 100-140 GeV, during LHC operation at a low luminosity. With 30 fb$^{-1}$ of accumulated data and for $M_H=120$ GeV about 100 signal events could be observed with the number of background events larger by a factor of 2 only, showing a signal significance $S/\sqrt{B}\sim 7$. We use the difference of distributions in the partonic subprocess energy $\sqrt{\hat s}$ for the signal and background for a better separation of the signal.

hep-ph

Discovery potential for supersymmetry in CMS

This work summarizes and puts in an overall perspective studies done within CMS concerning the discovery potential for squarks and gluinos, sleptons, charginos and neutralinos, SUSY dark matter, lightest Higgs, sparticle mass determination methods and the detector design optimisation in view of SUSY searches. It represents the status of our understanding of these subjects as of Summer 1997. As a benchmark model we used the minimal supergravity-inspired super- symmetric standard model (mSUGRA) with a stable LSP. Discovery of SUSY at the LHC should be relatively straightforward. It may occur through the observation of a large excesses of events in missing E_T + jets, or with one or more isolated leptons. An excess of trilepton events or of isolated dileptons with E_T^miss, exhibiting a characteristic signature in the l^+l^- invariant mass distribution could also be the first manifestation of SUSY production. Squark and gluino production may represent a copious source of Higgs bosons through cascade decays. The lightest SUSY Higgs h->bbbar may be reconstructed with a signal/background ratio of order 1. The lightest supersymmetric particle of SUSY models with conserved R-parity represents a very good candidate for the cosmological dark matter. The region of parameter space where this is true is well-covered by our searches, at least for tan(beta)=2. If supersymmetry exists at electroweak scale it could hardly escape detection in CMS, and the study of supersymmetry will form a central part of our physics program.

hep-ph