17,768 research outputs found
Next-to-leading-order QCD corrections to
The associated production of Higgs boson with a hard photon at lepton
collider, i.e., , is known to bear a rather small cross
section in Standard Model, and can serve as a sensitive probe for the potential
new physics signals. Similar to the loop-induced Higgs decay channels , the process also starts at one-loop
order provided that the tiny electron mass is neglected. In this work, we
calculate the next-to-leading-order (NLO) QCD corrections to this associated
production process, which mainly stem from the gluonic dressing to
the top quark loop. The QCD corrections are found to be rather modest at lower
center-of-mass energy range ( GeV), thus of negligible impact on
Higgs factory such as CEPC. Nevertheless, when the energy is boosted to the ILC
energy range ( GeV), QCD corrections may enhance the
leading-order cross section by . In any event, the
process has a maximal production rate fb around
GeV, thus CEPC turns out to be the best place to look for this
rare Higgs production process. In the high energy limit, the effect of NLO QCD
corrections become completely negligible, which can be simply attributed to the
different asymptotic scaling behaviors of the LO and NLO cross sections, where
the former exhibits a milder decrement , but the latter undergoes
a much faster decrease .Comment: v4, 11 pages, 6 figures, 2 tables; errors in Appendix are fixed;
version accepted for publication at PL
Proton fraction in neutron stars
The proton fraction in {\sl \beta}-stable neutron stars is investigated
within the framework of the Skyrme-Hartree-Fock theory using the extended
Skyrme effective interaction for the first time. The calculated results show
that the proton fraction disappears at high density, which implies that the
pure neutron matter may exist in the interior of neutron stars. The
incompressibility of the nuclear equation of state is shown to be more
important to determine the proton fraction. Meanwhile, it is indicated that the
addition of muons in neutron stars will change the proton fraction. It is also
found that the higher-order terms of the nuclear symmetry energy have obvious
effects on the proton fraction and the parabolic law of the nuclear symmetry
energy is not enough to determine the proton fraction.Comment: 4 Pgaes in REVTex, 2 Figures, 1 Tabl
Contributions of hyperon-hyperon scattering to subthreshold cascade production in heavy ion collisions
Using a gauged flavor SU(3)-invariant hadronic Lagrangian, we calculate the
cross sections for the strangeness-exchange reactions YY to N\Xi (Y=\Lambda,
\Sigma) in the Born approximation. These cross sections are then used in the
Relativistic Vlasov-Uehling-Uhlenbeck (RVUU) transport model to study \Xi
production in Ar+KCl collisions at incident energy of 1.76A GeV and impact
parameter b=3.5 fm. We find that including the contributions of hyperon-hyperon
scattering channels strongly enhances the yield of \Xi, leading to the
abundance ratio \Xi^{-}/(\Lambda+\Sigma^{0})=3.38E-3, which is essentially
consistent with the recently measured value of by the HADES collaboration at GSI.Comment: 8 pages, 5 figure
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