25 research outputs found
Top quark spin in ep collision
We discuss the degree of spin polarization of single top quarks produced via
fusion process in collision at TESLA+HERAp and CLIC+LHC energies
and 5.3 TeV. A description on how to combine the cross sections
of and processes is given.
-beam direction is taken to be the favorite top quark spin decomposition
axis in its rest frame and it is found to be comparable with the ones in
collision. It is argued that theoretical simplicity and experimental clearness
are the advantage of collision.Comment: 2 eps figure
Anomalous Quartic and Couplings in Collision With Initial Beams and Final State Polarizations
The constraints on the anomalous quartic and
gauge boson couplings are investigated through the processes
and . Considering the
longitudinal and transverse polarization states of the final W or Z boson and
incoming beam polarizations we find 95% confidence level limits on the
anomalous coupling parameters and with an integrated luminosity
of 500 and =0.5, 1 TeV energies. Assuming the
couplings are independent of the
couplings we show that the longitudinal polarization state of the final gauge
boson improves the sensitivity to anomalous couplings by a factor of 2-3
depending on energy and coupling. An extra enhancement in sensitivity by a
factor of 1.3 comes from a set of initial beam polarizations
and couplings in collision with polarized beams
The potential of e mode of linear collider to probe
and vertices is investigated through the Z boson
production from the procees . Considering the longitudinal and
transverse polarization states of the Z boson and incoming polarized beams we
find the 95% C.L. limits on the form factors , ,
and with integrated luminosity 500
and 0.5, 1, 1.5 TeV energies. It is shown that the polarization can
improve sensitivities by factors 2-3 depending on the energy.Comment: 12 pages, 8 EPS figure
Top Quark Spin Polarization in ep Collision
We discuss the degree of spin polarization of single top quarks produced via
fusion process in collision at TESLA+HERAp and CLIC+LHC energies
and 5.3 TeV. For subprocess we show that
the top quark spin is completely polarized when the spin basis is chosen in the
direction of the incoming positron beam in the rest frame of top quark. A
description on how to combine the cross sections of and
processes is given. -beam direction is
taken to be the favorite top quark spin decomposition axis in its rest frame
and it is found to be comparable with the ones in collision. It is argued
that theoretical simplicity and experimental clearness are the advantage of
collision.Comment: Revised version of Phys. Rev. D69 (2004)03401
Realistic constraints on the doubly charged bilepton couplings from Bhabha scattering with LEP data
Upper limits on doubly charged bilepton couplings and masses are extracted
from LEP data for Bhabha scattering at energy range GeV
using standard model program ZFITTER which calculates radiative corrections. We
find that at 95% C.L. for scalar and
vector bileptons.Comment: 5 pages, 1 EPS figur
Anomalous Wtb Coupling in ep Collision
The potential of ep collision to prospect for anomalous Wtb vertex is
discussed from the single top quark production process for
TESLA+HERAp and CLIC+LHC energies. Sensitivities to anomalous couplings
and , in the case of CLIC+LHC, are shown to be comparable with
LHC.Comment: 10 pages, 4 figure
Anomalous WW-Gamma Vertex in Gamma-p Collision
The potential of LC+HERAp based Gamma-p collider to probe WW-Gamma vertex is
presented through the discussion of sensitivity to anomalous couplings and P_T
distribution of the final quark. The limits of -0.04<\Delta\kappa<0.04 and
-0.11<\lambda<0.11 at 95% C.L. can be reached with integrated luminosity
200(1/pb). The limit for \Delta\kappa is comparable to one which is expected
from LHC. The bounds are also obtained from corresponding ep collider using
Weizsacker-Williams Approximation to compare with real photons.Comment: 8 pages, 2 eps figure
Archaeogenetic analysis of Neolithic sheep from Anatolia suggests a complex demographic history since domestication
Sheep were among the first domesticated animals, but their demographic history is little understood. Here we analyzed nuclear polymorphism and mitochondrial data (mtDNA) from ancient central and west Anatolian sheep dating from Epipaleolithic to late Neolithic, comparatively with modern-day breeds and central Asian Neolithic/Bronze Age sheep (OBI). Analyzing ancient nuclear data, we found that Anatolian Neolithic sheep (ANS) are genetically closest to present-day European breeds relative to Asian breeds, a conclusion supported by mtDNA haplogroup frequencies. In contrast, OBI showed higher genetic affinity to present-day Asian breeds. These results suggest that the east-west genetic structure observed in present-day breeds had already emerged by 6000 BCE, hinting at multiple sheep domestication episodes or early wild introgression in southwest Asia. Furthermore, we found that ANS are genetically distinct from all modern breeds. Our results suggest that European and Anatolian domestic sheep gene pools have been strongly remolded since the Neolithic
Polarized Single Top Quark Production in e\gamma Collision and Anomalous Wtb Couplings
We investigate the potential of collisions to probe anomalous
couplings via the polarized single top quark production process . We find 95% confidence level limits on the
anomalous coupling parameters and with an integrated
luminosity of and and 1.5 TeV energies. The
effects of top quark spin polarization on the anomalous couplings are
discussed. It is shown that polarization leads to a considerable improvement in
the sensitivity limits.Comment: published versio