189 research outputs found
Project {\tt SANC} (former {\tt CalcPHEP}): Support of Analytic and Numeric calculations for experiments at Colliders
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
[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 in the one-loop
approximation.Comment: 3 Latex, Presented at ICHEP2002, Amsterdam, July 24-30, 2000;
Submitted to Proceeding
Nonmigrating tidal activity related to the sudden stratospheric warming in the Arctic winter of 2003/2004
This paper is focused on the nonmigrating tidal activity seen in the SABER/TIMED temperatures that is related to the major sudden stratospheric warming (SSW) taking place in the Arctic winter of 2003/2004. The emphasis is on the nonmigrating diurnal tides observed in the stratosphere and lower mesosphere which is usually accepted to be insignificant in comparison with that in the upper mesosphere and thermosphere. By using different independent spectral methods we found a significant amplification in December–January of the following nonmigrating 24-h tides: zonally symmetric (<I>s</I>=0), eastward propagating with zonal wavenumber 1 (E1), and westward propagating with zonal wavenumbers 2 and 3 (W2 and W3) tides. It has been found that the double peak nonmigrating tidal amplifications located in the stratosphere (~40 km) and in the lower mesosphere (~70 km) are a consequence of the maintained hydrostatic relation. By detailed comparison of the evolution and spatial structure of the nonmigrating diurnal tides with those of the migrating diurnal tide and stationary planetary waves (SPWs) evidence for a SPW-migrating tide interaction as a source of nonmigrating tides has been presented. Therefore, the nonmigrating 24-h tides turn out to be an important component of the middle atmosphere dynamics during the major SSW in the Arctic winter of 2003/2004
SANC integrator in the progress: QCD and EW contributions
Modules and packages for the one-loop calculations at 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, ff->HW(Z) 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
Genetic-parameter estimation of milk yield in White Maritza sheep breed using different test day models
The aims of this study were to estimate the genetic parameters of the
test day milk yield (TDMY) of the White Maritza sheep breed population and to
choose the most appropriate linear models for genetic-parameter estimation
of test day milk yield. The White Maritza sheep breed is a multipurpose
native sheep breed in Bulgaria. Test day milk yield data were collected from
1992 to 2015 (24Â years). Milk yield recordings were made in 18 flocks
according to the AC method (official milk recording by ICAR regulations). The database includes 8768 test day milk yield records
belonging to 987 ewes. The pedigree file includes 1937 animals. Nine test
day models (TDMs) were formulated and tested for the estimation of the genetic
parameters of milk yield. The first three models were repeatability models
(REP models), the second three were random regression models (RRMs), and the
last three models were also random regression models with an added Ali and
Schaeffer regression to describe the lactation curve using first-, second-
and third-order polynomials. The average TDMY was 764.47 mL. There were no
significant differences in the values of heritability (h2) calculated by the three REP
models: REP1 0.355 ± 0.060, REP2 0.344 ± 0.047 and REP3 0.347 ± 0.060. The same applied to the repeatability coefficients,
which, for the three REP models, were 0.384 ± 0.065, 0.376 ± 0.051
and 0.378 ± 0.065, respectively. Based on REP model 1, three models
with random regression RRM1, RRM2 and RRM3 were constructed, which is
associated with the use of first-, second- and third-order polynomials (for the random effects of both the animal and the permanent environment). The
trajectories of h2 calculated by the three RRMs were not similar and
demonstrated some differences, both at the beginning and in the middle of
the milking period. The RRM with third-order polynomials demonstrated more
genetic diversity until the 165th day of lactation, but Akaike information criterion (AIC), Bayesian information criterion (BIC) and log-likelihood (LogL)
estimates were higher. The regression models with first- and second-degree
polynomials were insufficient to reveal genetic diversity to a higher degree
than REP model 1. The trend in the trajectories of h2 calculated by the
three random regression models with Ali and Schaeffer regression models
(ASRMs) was similar to that of random regression models without
the Ali and Schaeffer regression incorporated. Although the noted advantages of
the random regression models revealed, to a greater extent, the genetic
diversity of test day milk yield, AIC, BIC and LogL estimates indicated that
repeatability models achieved a better balance between complexity and
fitness and a smaller prediction error compared to random regression models.</p
PHOTOS Monte Carlo and its theoretical accuracy
Because of properties of QED, the bremsstrahlung corrections to decays of
particles or resonances can be calculated, with a good precision, separately
from other effects. Thanks to the widespread use of event records such
calculations can be embodied into a separate module of Monte Carlo simulation
chains, as used in High Energy Experiments of today. The PHOTOS Monte Carlo
program is used for this purpose since nearly 20 years now. In the following
talk let us review the main ideas and constraints which shaped the program
version of today and enabled it widespread use. Finally, we will underline
importance of aspects related to reliability of program results: event record
contents and implementation of channel specific matrix elements.Comment: Presented by Z. Was, April 08 2008, International Workshop on e+e-
collisions from Phi to Ps
Standard SANC modules for NLO QCD Radiative Corrections to Single-top Production
It this paper we present the results obtained with the newly created Standard
SANC modules for calculation of the NLO QCD corrections to single top
production processes in s and t channels at the partonic level, as well as
top-decays. The main aim of these results is to prove the correct work of
modules. A comprehensive comparison with results of the CompHEP system is
given, where possible. These modules are intended to be used in Monte Carlo
generators for single top production processes at the LHC. As in our recent
paper, devoted to the electroweak corrections to these processes, we study the
regularization of the top-legs associated infrared divergences with aid of the
complex mass of the top quark. A comparison of QCD corrections with those
computed by the conventional method is presented both for top production and
decays. For s channel production we give an analytic proof of equivalence of
the two methods in the limit of low top width.Comment: 21 pages, 2 figures, 17 table
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