Radiative corrections to the single top
s
and
t
channel production processes are revisited. Complete one-loop electroweak corrections are calculated within the SANC system. New is a study of the ...regularization of the top-leg associated infrared divergences with aid of the complex mass of the top quark. A comparison of these electroweak corrections with those computed by the conventional method is presented both for top production and decays. Standard FORM and FORTRAN SANC modules are created. These modules are compiled into a package sanc_cc_v1.40, which may be downloaded from the SANC project homepages. Many numerical results are presented at the partonic level with the aim to demonstrate the correct working of the modules. These modules are intended to be used in Monte Carlo generators for single top production at the LHC. Where possible, we compare our results with those existing in the literature; in particular, a comprehensive comparison with results of the CompHEP system is given.
Modules and packages for the one-loop calculations at the partonic level represent the first level of SANC output computer product. The next level represents Monte Carlo integrator
mcsanc
, realizing ...fully differential hadron level calculations (convolution with PDF) for the HEP processes at LHC. In this paper we describe the implementation into the framework mcsanc first set of processes: DY NC, DY CC,
and single top production. Both EW and QCD NLO corrections are taken into account. A comparison of SANC results with those existing in the world literature is given.
J functions for the process ud→WA Bardin, D. Yu; Kalinovskaya, L. V.; Uglov, E. D. ...
Physics of atomic nuclei,
01/2016, Letnik:
79, Številka:
1
Journal Article
Recenzirano
Odprti dostop
In this paper we present a description of the universal approach for analytic calculations for a certain class of
J
functions for six topologies of the boxes for the process
ud
→
WA
. These functions
...J
arise at the reduction of the infrared divergent box diagrams. The standard Passarino–Veltman reduction of the four-point box diagram with an internal photon line connecting two external lines on the mass shell leads to infrared-divergent and mass-singular
D
0
functions. In the system SANC a systematic procedure is adopted to separate both types of singularities into the simplest objects, namely
C
0
functions. The functions
J
, in turn, are represented as certain linear combinations of the standard
D
0
and
C
0
functions. The subtracted
J
functions are free of both types of singularities and are expressed as explicit and compact linear combinations of dilogarithm functions. We present extensive comparisons of numerical results of SANC with those obtained with the aid of the LoopTools package.
In this article we have summarized the status of the system
SANC version
1.00. We have implemented theoretical predictions for many high energy interactions of fundamental particles at the one-loop ...precision level for up to 4-particle processes. In the present part of our
SANC description we place emphasis on an extensive discussion of an important first step of calculations of the one-loop amplitudes of 3- and 4-particle processes in QED, QCD and EW theories.
Title of program:
SANC
Catalogue identifier: ADXK_v1_0
Program summary URL:
http://cpc.cs.qub.ac.uk/summaries/ADXK_v1_0
Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland
Designed for: platforms on which Java and FORM3 are available
Tested on: Intel-based PC's
Operating systems: Linux, Windows
Programming languages used: Java, FORM3, PERL, FORTRAN
Memory required to execute with typical data: 10 Mb
No. of bytes in distributed program, including test data, etc.: 3 658 844
No. of bits in a word: 32
No. of processors used: 1 on
SANC server, 1 on
SANC client
Distribution format: tar.gz
Nature of physical 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.
Method of solution: Numerical computation of analytical formulae of form factors and helicity amplitudes. For simulation of two fermion radiative decays of Standard Model bosons
(
W
±
,
Z
)
and the Higgs boson a Monte Carlo technique is used.
Restrictions on the complexity: In the current version of
SANC there are 3 and 4 particle processes and decays available at one-loop precision level.
Typical running time: The running time depends on the selected process. For instance, the symbolic calculation of form factors (with precomputed building blocks) of Bhabha scattering in the Standard Model takes about 15 s, helicity amplitudes—about 30 s, and bremsstrahlung—10 s. The numerical computation of cross-section for this process takes about 5 s (CPU 3 GHz IP4, RAM 512 Mb, L2 1024 KB).
SANC: the process γγ → ΖΖ Bardin, D.; Bondarenko, S.; Christova, P. ...
Physics of particles and nuclei letters,
11/2017, Letnik:
14, Številka:
6
Journal Article
Recenzirano
The implementation of the process γγ →
ΖΖ
at the one-loop level within SANC system multichannel approach is considered. The derived one-loop scalar form factors can be used for any cross channel ...after an appropriate permutation of their arguments–Mandelstam variables
s
,
t
,
u
. To check of the correctness of the results we observe the independence of the scalar form factors on the gauge parameters and the validity of Ward identity (external photon transversality). We present the complete analytical results for the covariant and tensor structures and helicity amplitudes for this process. We make an extensive comparison of our analytical and numerical results with those existing in the literature.
SANCnews: Sector 4f, charged current Arbuzov, A.; Bardin, D.; Bondarenko, S. ...
The European physical journal. C, Particles and fields,
8/2007, Letnik:
51, Številka:
3
Journal Article
Recenzirano
Odprti dostop
In this paper we describe the implementation of the charged current decays of the type t→bl+νl(γ) in the framework of the SANC system. All calculations are done taking into account the one-loop ...electroweak correction in the standard model. The emphasis of this paper is on the presentation of numerical results. Various distributions are produced by means of a Monte Carlo integrator and event generator. Comparison with the results of the CompHEP and PYTHIA packages are presented for the Born and hard photon contributions. The validity of the cascade approximation at one-loop level is also studied.
We have calculated the electroweak radiative corrections at the
level to the three channels of the process f
1
f̄
1
ZA→0 and implemented them into the SANC system. Here A stands for the photon and f
...1
for a first generation fermion whose mass is neglected everywhere except in the arguments of logarithmic functions. The symbol →0 means that 4-momenta of all the external particles flow inwards. We present the complete analytical results for the covariant and helicity amplitudes for three cross channels: f
1
f̄
1
→Zγ, Z→f
1
f̄
1
γ and f
1
γ→f
1
Z. The one-loop scalar form factors of these channels are simply related by an appropriate permutation of their arguments, s,t,u. To check the correctness of our results we first of all observe the independence of the scalar form factors on the gauge parameters and the validity of the Ward identity, i.e. external photon transversality, and, secondly, compare our numerical results with the other independent calculations available to us.
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