15,356 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
Holographic R\'enyi entropy in AdS/LCFT correspondence
The recent study in AdS/CFT correspondence shows that the tree level
contribution and 1-loop correction of holographic R\'enyi entanglement entropy
(HRE) exactly match the direct CFT computation in the large central charge
limit. This allows the R\'enyi entanglement entropy to be a new window to study
the AdS/CFT correspondence. In this paper we generalize the study of R\'enyi
entanglement entropy in pure AdS gravity to the massive gravity theories at
the critical points. For the cosmological topological massive gravity (CTMG),
the dual conformal field theory (CFT) could be a chiral conformal field theory
or a logarithmic conformal field theory (LCFT), depending on the asymptotic
boundary conditions imposed. In both cases, by studying the short interval
expansion of the R\'enyi entanglement entropy of two disjoint intervals with
small cross ratio , we find that the classical and 1-loop HRE are in exact
match with the CFT results, up to order . To this order, the difference
between the massless graviton and logarithmic mode can be seen clearly.
Moreover, for the cosmological new massive gravity (CNMG) at critical point,
which could be dual to a logarithmic CFT as well, we find the similar agreement
in the CNMG/LCFT correspondence. Furthermore we read the 2-loop correction of
graviton and logarithmic mode to HRE from CFT computation. It has distinct
feature from the one in pure AdS gravity.Comment: 28 pages. Typos corrected, published versio
Interaction effect in two-dimensional Dirac fermions
Based on the Dirac equations in the two-dimensional flux model, we
study the interaction effects both in nontrivial gapped and gapless Dirac
equations with numerical exact diagonalization method. In the presence of the
nearest and next nearest neighbor interactions: for nontrivial gapped Dirac
equation, the topological phase is robust and persists in a finite region of
the phase diagram; while for gapless Dirac equation, charge-density-wave and
stripe phases are identified and the phase diagram in plane is
obtained. When the next-next-nearest neighbor interaction is further included
to gapless Dirac equation, the topological phase expected in the mean-field
theory is absent. Our results are related to the possibility of dynamically
generating topological phase from the electronic correlations.Comment: 7 pages, 8 figures. More discussins are added; accepted for
publication in Physical Review
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