7,733 research outputs found
Single Top production at LHC
The Production of single top quarks at LHC provides an ideal framework to
investigate the properties of electroweak interaction, in particular of the
{\it tWb} coupling. Moreover, single top is a powerful mean to identify physics
beyond the standard model. All three different production mechanisms of single
top are expected to be observed at LHC. Recent studies from ATLAS and CMS are
presented.Comment: 5 pages, Presented at the XLIrst Rencontres de Moriond - QCD and High
Energy Hadronic Interaction
Probing the Anomalous Couplings of the Top Quark with Gluon at the LHC and Tevatron
In this paper, we study the sensitivity of the fraction of events
arising from gluon-gluon fusion to the chromoelectric and chromomagnetic dipole
moments (CEDM and CMDM) as well as the total and differential cross
sections at the LHC and Tevatron. The sensitivity of measured charged asymmetry
at the LHC to CEDM and CMDM is also studied. We find that at the Tevatron and
the LHC, non-zero values of CMDM could suppress the production rate.
It is shown that the ratio of at the Tevatron is more
sensitive to CEDM and CMDM than the LHC case. The presence of CEDM always
increases the contribution of gluon-gluon fusion process in top pair rate at
the Tevatron and LHC. Except for a small range of CMDM, the presence of CEDM
and CMDM can increase the fraction of gluon-gluon fusion at the Tevatron and
LHC. The measured ratio of at the Tevatron is used to
derive bounds on the chromoelectric and chromomagnetic dipole moments as well
as the total and differential () cross sections at the
LHC and Tevatron, and the measured charged asymmetry at the LHC. The
combination of and provides
stringent limits on CMDM and CEDM.Comment: 11 pages,6 figures,2 table
Secondary particles spectra in the decay of a polarized top quark with anomalous coupling
Analytic expression for energy and angular dependence of a secondary charged
lepton in the decay of a polarized top quark with anomalous couplings in
the presence of all anomalous couplings are derived. The angular distribution
of the b-quark is derived as well. It is presented that the charged lepton spin
correlation coefficient is not very sensitive to the anomalous couplings.
However, the b-quark spin correlation coefficient is sensitive to anomalous
couplings and could be used as a powerful tool for searching of non-SM
coupling.Comment: 9 pages, 5 figure
A new approach to the credibility formula
The usual credibility formula holds whenever, (i) claim size distribution is a member of the exponential family of distributions, (ii) prior distribution conjugates with claim size distribution, and (iii) square error loss has been considered. As long as, one of these conditions is violent, the usual credibility formula no longer holds. This article, using the mean square error minimization technique, develops a simple and practical approach to the credibility theory. Namely, we approximate the Bayes estimator with respect to a general loss function and general prior distribution by a convex combination of the observation mean and mean of prior, say, approximate credibility formula. Adjustment of the approximate credibility for several situations and its form for several important losses are given.Loss function Balanced loss function Mean square error technique
Study of anomalous top quark FCNC interactions via -channel of single top
The potential of the LHC for investigation of anomalous top quark
interactions with gluon () through the production of -channel of
single top quark is studied. In the Standard Model, the single top quarks in
the -channel mode are charge symmetric meaning that . However, the presence of anomalous FCNC
couplings leads to charge asymmetry. In this paper a method is proposed in
which this charge asymmetry may be used to constrain anomalous FCNC couplings.
The strength of resulting constraints is estimated for the LHC for the center
of mass energies of 7 and 14 TeV.Comment: 13 pages, 4 figures, new references adde
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