SANCnews: Sector image Original Research Article

In this paper we describe the implementation of processes image and image into the framework of SANC system. The image stands for a massless fermion f whose mass is kept non-zero only in arguments of ln functions and →0 means that all 4-momenta flow inwards. The derived scalar form factors can be used for any cross channel after an appropriate permutation of their arguments (image). We present the covariant and helicity amplitudes for these processes: for the former only in the annihilation channel image, while for the latter in annihilation image and decay image channels. We briefly describe additional precomputation modules which were not covered in the previous paper. For the processes image and decay image we present compact results of calculation of the accompanying bremsstrahlung and discuss exhaustive numerical results.As applications there are two types of the Monte Carlo generators for the process image. The first one is the generator based on a single resonance approximation for one of the Z bosons. The second one, exploiting the double resonance approximation, is not described in this article. For the generator in the single approximation we present a short description. Whenever possible, we compare our results with those existing in the literature. For example, we present a comparison of the results for image decay with those obtained by MC generator Prophecy4f. SANC client for version v.1.10 can be downloaded from servers at CERN and Dubna . Program summary Program title:SANC Catalogue identifier:ADXK_v1_1 Program summary URL: Program obtainable from:CPC Program Library, Queenʹs University, Belfast, N. Ireland Licensing provisions:Standard CPC licence, No. of lines in distributed program, including test data, etc.:23 274 No. of bytes in distributed program, including test data, etc.: 1 691 761 Distribution format:tar.gz Programming language:Java, FORM3, PERL, FORTRAN Computer:Intel-based PCs on which Java and FORM3 are available Operating system:Linux, Windows RAM:10 MB Word size:32 Classification:11.6 Does the new version supersede the previous version?:Yes Nature of problem:Automatic calculation of pseudo- and realistic observables for various processes and decays in the Standard Model of Electroweak interactions, QCD and QED at one-loop precision level. Form factors and helicity amplitudes free of UV divergences are produced. For exclusion of IR singularities the soft photon emission is included. Solution method:Numerical computation of analytical formulae of form factors and helicity amplitudes. For simulation of two fermion radiative decays of Standard Model bosons (image) and the Higgs boson a Monte Carlo technique is used. Reasons for new version:Implementation of new processes; extension of an automatic generation of FORTRAN codes by the s2n.f package onto many more processes; bug fixes. Summary of revisions:Implementation of light-by-light scattering into QED branch; vast update of 2f2b node in EW branch; complete renovation of QCD branch. Restrictions:In the current version of SANC there are 3 and 4 particle processes and decays available at one-loop precision level. Running time:The running time depends on the selected process. For instance, the symbolic calculation of form factors (with precomputed building blocks) for image process takes about 10 sec, helicity amplitudes—about 10 sec, and bremsstrahlung—1 min 10 sec. The relevant s2n runs take about 2 min 40 sec, 1 sec and 30 sec, respectively. The numerical computation of decay rate for this process (production of benchmark case 3 Table) takes about 5 sec (CPU 3 GHz IP4, RAM 512 Mb, L2 1024 KB). For purchase