V. Ilyin

CompHEP 4.4—automatic computations from Lagrangians to events

Abstract 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.

Two-loop gluon-condensate contributions to heavy-quark current correlators: exact results and approximations☆☆☆★★★

Abstract The coefficient functions of the gluon condensate 〈 G 2 〉, in the correlators of heavy-quark vector, axial, scalar and pseudoscalar currents, are obtained analytically, to two loops, for all values of z = q 2 4m 2 . In the limiting cases z → 0, z → 1, and z → − ∞, comparison are made previous results. Approximation methods, based on these limiting cases, are critically assessed, with a view to three-loop work. High accuracy is achieved using a few moments as input. A single moment, combined with only the leading threshold and asymptotic behaviour, gives the two-loop corrections to better than 1% in the next 10 moments. A two-loop fit to vector data yields 〈 α s π G 2 〉 ≈ 0.021 GeV 4 .

Higgs Boson Discovery Potential of LHC in the Channel pp→γγ+jet

Abstract We discuss the SM Higgs discovery potential of LHC in the reaction pp → H + jet → γγ + 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/ B ∼7 . We use the difference of distributions in the partonic subprocess energy s for the signal and background for a better separation of the signal.We discuss the SM Higgs discovery potential of LHC in the reaction

CompHEP 4.5 Status Report

pp\to H+ jet\to\gamma\gamma+jet

Associated Higgs boson production in γe collisions

when the jet is observed at sufficiently high

Sgoldstino events in top decays at the LHC

E_t

ATENSOR — REDUCE program for tensor simplification

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

Single leptoquark production associated with hard photon emission in ep collisions at high energies

^{-1}

TWO LOOP CALCULATIONS IN THE LARGE QUARK MASS EXPANSION IN THE FRAMEWORK OF THE QCD SUM RULES METHOD

of accumulated data and for

Higgs search in the WW* decay mode at photon linear colliders

M_H=120