We review the status of electroweak radiative corrections to top-pair
production at a Linear Collider well above the production threshold. We
describe the Fortran package topfit and present numerical results at sqrt(s) =
500 GeV, 1 TeV, and 3 TeV.Comment: 6 pages, LaTex, 2 tables, 1 figure, talk presented by T.R. at the
  Int. Workshop on Linear Colliders (LCWS 2002), 26-30 Aug 2002, Jeju Island,
  Kore

Fleischer, J.

Leike, A.

Riemann, T.

Werthenbach, A.

English

arXiv

We review the status of electroweak radiative corrections to top-pair production at a Linear Collider well above the production threshold. We describe the Fortran package topfit and present numerical results at sqrt(s) = 500 GeV, 1 TeV, and 3 TeV.We review the status of electroweak radiative corrections to top-pair production at a Linear Collider well above the production threshold. We describe the Fortran package topfit and present numerical results at sqrt(s) = 500 GeV, 1 TeV, and 3 TeV

CERN Document Server

DESY 02{203 ISSN 0418{9833hep-ph/0211428Status of Electroweak Corrections to Top PairProduction yJ. Fleischer1z, A. Leike2, T. Riemann3, A. Werthenbach3;41 Fakulta¨t f. Physik, Universita¨t Bielefeld, 33615 Bielefeld, Germany2 Sektion Physik der Universita¨t Mu¨nchen, 80333 Mu¨nchen, Germany3 Deutsches Elektronen-Synchrotron, DESY Zeuthen, 15738 Zeuthen, Germany4 Theory Division, CERN, 1211 Geneva 23, SwitzerlandAbstractWe review the status of electroweak radiative corrections to top-pair production ata Linear Collider well above the production threshold. We describe the Fortranpackage topfit and present numerical results atps = 500 GeV, 1 TeV, and 3 TeV.∗Talk presented by T. Riemann at Int. Workshop on Linear Colliders (LCWS 2002), 26{30 Aug2002, Jeju Island, Korea†Work supported in part by the European Community’s Human Potential Programme undercontract HPRN{CT{2000{00149 Physics at Colliders‡E-mails: fl@physik.uni-bielefeld.de, leike@theorie.physik.uni-muenchen.de,Tord.Riemann@desy.de, Anja.Werthenbach@desy.de1 IntroductionNot too much is known about top quarks, and what is known is not as accurate asdesired [1]. At a Linear Collider, top-pair production will be one of the dominantand most interesting processes. Very precise measurements are expected. Therefore,the cross-sections have to be predicted with a precision of few per mil [2, 3]. Twoquite dierent experimental set-ups are of interest. One is the top-pair productionthreshold region, where one expects to get precise values of mass and width. Theother one is continuum production at high energy with the hope to get access tosome anomalous behavior, potentially manifested in abnormal couplings and/or newnal state signatures. Here, we calculate the electroweak Standard Model expecta-tions with one-loop corrections. Earlier series of studies are [4, 5] and [6, 7], anda recent one is [8, 9]. With our study, detailed comparisons of the diverse resultswere undertaken for the rst time [10, 11]. We used the package DIANA [12, 13]for automatic generation of the diagrams and FORM [14] for the further symboliccalculations, and for the numerics the Fortran packages FF [15] and LoopTools [16].2 The Fortran Package topfitThe package topfit [17, 18] was written in order to have a tool for the numericalestimation of the electroweak corrections to top-pair production. We wanted alsoto have some flexibility for an easy comparison with other codes. As a result, theuser of our program may switch on and o several options and may adjust inputparameters. The list in Table 1 is by far not complete. Of course, the usual standardmodel parameters in the on-mass-shell scheme (particle masses and αem(0)) may bechosen. The numerical input is as in [10]. Three dierent options may be chosen forthe output: Dierential and integrated cross-sections and asymmetries in the StandardModel Cross-sections and asymmetries with photonic corrections only, at xed Borncouplings Six weak form factors, with/without running αem2Flag DescriptionIFINAL choice of nal state particleIQED inclusion of photonic correctionsCNINI initial state correctionsCNFIN nal state correctionsCNINT interference correctionsIWEAK Born or use LoopTools or use FFGAMS choice of Z widthIQEDAA running of αemIPHOTM nite photon mass or dimensional regularisation of the IR divergencyIDCOST top quark angular distributionICOSTI integrated cross-section and asymmetryIHARD inclusion of hard bremsstrahlungSPRCUT photonic phase space cutTable 1: A collection of flags of topfit; more details may be found in [17].The latter output might be useful for a Monte Carlo approach to QED and QCDcorrections, but also for an estimate of the weak corrections.3 Numerical Results and ConclusionsFor comparisons with the results of other groups, with very satisfactory numericalagreements, we refer to [10, 11]. Of course, one has to bear in mind that thesecomparisons control not more than what is called ‘technical precision’. In Figure 1we show the order of magnitude of the cross-sections, and in Table 2 purely weakform factors atps = 3 TeV. To dene the normalizations of F 113 and F513 , we mentionthat dσ  Re[(u2 + t2 + 2m2t s)jF 111 j2 + 2mt(ut − m4t )(F 111 F 113 + F 511 F 513 )] + . . . ,and t = s(1− βt cos θ)/2.The treatment of the one-loop electroweak corrections to top-pair production iswell under control up tops = 3 TeV. Of course, there is much Standard Modelphysics to be included in addition: higher orders, notably in the photonic part, butalso numerically large QCD corrections, and nally also phenomena like top-quark3f.f. Born Born + weak correctionsF 111 {3.4822175 E{09, 0 {2.4672033 E{09, +5.6471323 E{12F 151 +2.0992410 E{10, 0 {4.6533609 E{10, {3.4235887 E{10F 511 +7.5582979 E{10, 0 +1.4831421 E{10, {2.6754148 E{10F 551 {1.8476412 E{09, 0 {1.4913239 E{09, +3.4972393 E{10mtF113 0, 0 +2.9895163 E{12, {6.6708986 E{13mtF513 0, 0 {2.4939160 E{12, +9.1292861 E{13Table 2: Weak form factors for dσ/d cos θ atps=3 TeV, cos θ=0.7. They yieldσB=0.076266014 pb and σweak=0.012482585 pb, correspondingly. The normaliza-tion corresponds to F 11;γ1;Born = e2QeQt/s (see also [10]); some flags chosen: IWEAK= 1, GAMS = {1, IQED = IQEDAA = 0.decays, other background reactions (of dierent signatures like e+e− ! tWb, tbl1l2,6f), or beamstrahlung.Acknowledgments. T.R. and A.W. would like to thank the organizers ofLCWS 2002 for the opportunity to visit an interesting, well-organized, and pleasantconference. F.J. and A.L. would like to thank DESY for support.References[1] E. Simmons, talk at HCP2002, preprint BUHEP-02-39, hep-ph/0211335.[2] ECFA/DESY LC Physics Working Group (J. Aguilar-Saavedra et al.), \TESLATechnical Design Report Part III: Physics at an e+e− Linear Collider", preprintDESY 2001{011 (2001), hep-ph/0106315.[3] American Linear Collider Working Group (T. Abe et al.), \Linear colliderphysics resource book for Snowmass 2001", Fermilab preprint FERMILAB-PUB-01-058-E (2001).[4] J. Fujimoto and Y. Shimizu, Mod. Phys. Lett. 3A (1988) 581.[5] F. Yuasa et al., Prog. Theor. Phys. Suppl. 138 (2000) 18{23.[6] W. Beenakker et al., Nucl. Phys. B365 (1991) 24{78.4[7] W. Hollik and C. Schappacher, Nucl. Phys. B545 (1999) 98{140.[8] D. Bardin et al., Dubna preprint JINR E2{2000{292 (2000), hep-ph/0012080,v.2 (12 Dec 2001).[9] A. Andonov et al., CERN-TH/2001-308 (2001), CERN-TH/2002-068 (2002).[10] J. Fleischer, T. Hahn, W. Hollik, T. Riemann, C. Schappacher, and A. Werthen-bach, \Complete electroweak one-loop radiative corrections to top- pair pro-duction at TESLA: A comparison", DESY preprint TESLA LC-TH-2002-002(2002), hep-ph/0202109.[11] J. Fleischer, J. Fujimoto, T. Ishikawa, A. Leike, T. Riemann, Y. Shimizu, andA. Werthenbach, \One-loop corrections to the process e+e− ! tt includinghard bremsstrahlung", preprint DESY 02-025 (2002), hep-ph/0203220.[12] M. Tentyukov and J. Fleischer, Comp. Phys. Comm. 132 (2000) 124{141.[13] M. Tentyukov and J. Fleischer, \DIANA, a program for Feynman diagramevaluation", hep-ph/9905560, see alsohttp://www.physik.uni-bielefeld.de/~tentukov/diana.html.[14] J. Vermaseren, \Symbolic manipulation with FORM" (Computer Algebra Ned-erland, Amsterdam, 1991).[15] G. van Oldenborgh, Comp. Phys. Comm. 66 (1991) 1{15.[16] T. Hahn and M. Perez-Victoria, Comp. Phys. Comm. 118 (1999) 153{165.[17] J. Fleischer, A. Leike, T. Riemann, and A. Werthenbach, Fortran programtopfit.F v.0.911 (15 Nov 2002), http://www-zeuthen.desy.de/~riemann/.[18] J. Fleischer, A. Leike, T. Riemann, and A. Werthenbach, in preparation.5Figure 1: Dierential cross-sections in Born approximation (solid lines), with weakcorrections (dashed), and with full electroweak corrections (no cut; dotted). Fromabove:ps = 0.5, 1, 3 (in TeV).6

Status of Electroweak Corrections to Top Pair Production

Fleischer J, Leike A, Riemann T, Werthenbach A. Status of electroweak corrections to top pair production.  2002

Status of Electroweak Corrections to Top Pair Production

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