4,860 research outputs found

    12 Years of Precision Calculations for LEP. What's Next?

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    I shortly review time period of twelve years, 1989-2000, which was devoted to a theoretical support of experiments at LEP and SLC at Z resonance and discuss several directions of possible future work in the field of precision theoretical calculations for experiments at future colliders.Comment: 11 Latex, including 1 figures. Updated version as appeared in the Journa

    The American National Exhibition and Kitchen Debates: How the World\u27s Superpowers Portrayed the Events of the Summer of 1959 to Meet National Needs

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    An undergraduate research paper centered on the investigation of American and Soviet propaganda efforts during and immediately after the Kitchen Debate of 1959

    Project {\tt SANC} (former {\tt CalcPHEP}): Support of Analytic and Numeric calculations for experiments at Colliders

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    The project, aimed at the theoretical support of experiments at modern and future accelerators -- TEVATRON, LHC, electron Linear Colliders (TESLA, NLC, CLIC) and muon factories, is presented. Within this project a four-level computer system is being created, which must automatically calculate, at the one-loop precision level the pseudo- and realistic observables (decay rates and event distributions) for more and more complicated processes of elementary particle interaction, using the principle of knowledge storing. It was already used for a recalculation of the EW radiative corrections for Atomic Parity Violation [1] and complete one-loop corrections for the process e+ettˉe^+ e^-\to t\bar{t} [2-4]; for the latter an, agreement up to 11 digits with FeynArts and the other results is found. The version of {\tt SANC} that we describe here is capable of automatically computing the decay rates and the distributions for the decays Z(H,W)ffˉZ(H,W)\to f\bar{f} in the one-loop approximation.Comment: 3 Latex, Presented at ICHEP2002, Amsterdam, July 24-30, 2000; Submitted to Proceeding

    J_AW,WA functions in Passarino-Veltman reduction

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    In this paper we continue to study a special class of Passarino-Veltman functions J arising at the reduction of infrared divergent box diagrams. We describe a procedure of separation of two types of singularities, infrared and mass singularities, which are absorbed in simple C0 functions. The infrared divergences of C0's can be regularized then by any method: photon mass, dimensionally or by the width of an unstable particle. Functions J, in turn, are represented as certain linear combinations of the standard D0 and C0 Passarino-Veltman functions. The former are free of both types of singularities and are expressed as explicit and compact linear combinations of logarithms and dilogarithm functions. We present extensive comparisons of numerical results with those obtained with the aid of the LoopTools package

    Off shell W pair production in e+ e- annihilation: The CC11 process

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    The various four-fermion production channels in e+ee^+ e^- annihilation are discussed and the {\tt CC11} process e+efˉ1uf1df2ufˉ2de^+ e^- \rightarrow {\bar f}_1^u f_1^d f^u_2 {\bar f}_2^d, {\mbox{ff\neqee}}, is studied in detail. The cross section d2σ/ds1ds2d^2\sigma/ds_1ds_2, with s1,s2s_1,s_2 being the invariant masses squared of the two fermion pairs, may be expressed by six generic functions. All but one may be found in the literature. The cross section, including initial state radiation and the Coulomb correction, is discussed and compared with other calculations from low energies up to s\sqrt{s} = 2 ~TeV.Comment: 28 pages, LaTex, 6 figures, 8 tables, a uuencoded file containing the latex file and figures is available via anonymous ftp at ftp://ftp.ifh.de/pub/preprint/desy95-167.uu and the complete ps file also from http://www.ifh.de/~riemann/desy95-167.ps.g

    An electroweak library for the calculation of EWRC to e+ e- --> f fbar within the CalcPHEP project

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    We present a description of calculations of the electroweak amplitude for e+ e- --> f fbar process. The calculations are done within the OMS (on-mass-shell) renormalization scheme in two gauges: in Rxi, which allows an explicit control of gauge invariance by examining cancellation of gauge parameters and search for gauge-invariant subsets of diagrams, and in the unitary gauge as a cross-check. The formulae we derived are realized in a FORTRAN code eeffLib, which is being created within the framework of the project CalcPHEP. We present a comprehensive comparison between eeffLib results for the light top with corresponding results of the well-known program ZFITTER for the u ubar channel, as well as a preliminary comparison with results existing in the world literature.Comment: Revised version, 47 Latex, including 14 figures (2 eps figures), 5 table
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