13,818 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
Short-range force between two Higgs bosons
The -wave scattering length and the effective range of the Higgs boson in
Standard Model are studied using effective-field-theory approach. After
incorporating the first-order electroweak correction, the short-range force
between two Higgs bosons remains weakly attractive for GeV. It is
interesting to find that the force range is about two order-of-magnitude larger
than the Compton wavelength of the Higgs boson, almost comparable with the
typical length scale of the strong interaction.Comment: v2, 11 pages, 2 figures, the version accepted for publication in
Phys. Lett.
Reconciling the nonrelativistic QCD prediction and the data
It has been a long-standing problem that the rare electromagnetic decay
process is plagued with both large and negative radiative
and relativistic corrections. To date it remains futile to make a definite
prediction to confront with the branching fraction of
recently measured by the \textsf{CLEO-c} and \textsf{BESIII} Collaborations. In
this work, we investigate the joint perturbative and relativistic correction
(i.e. the correction, where denotes the
characteristic velocity of the charm quark inside the ) for this decay
process, which turns out to be very significant. After incorporating the
contribution from this new ingredient, with the reasonable choice of the input
parameters, we are able to account for the measured decay rates in a
satisfactory degree.Comment: 7 pages, 1 figure, version accepted for publication in PRD R
Next-to-next-to-leading-order QCD corrections to at factories
Within the nonrelativistic QCD (NRQCD) factorization framework, we compute
the long-awaited correction for the exclusive double
charmonium production process at factories, i.e.,
at GeV. For the first time, we confirm that NRQCD
factorization does hold at next-to-next-to-leading-order (NNLO) for exclusive
double charmonium production. It is found that including the NNLO QCD
correction greatly reduces the renormalization scale dependence, and also
implies the reasonable perturbative convergence behavior for this process. Our
state-of-the-art prediction is consistent with the BaBar measurement.Comment: 6 pages, 2 figures, 1 tabl
Can NRQCD explain the transition form factor data?
Unlike the bewildering situation in the form factor,
a widespread view is that perturbative QCD can decently account for the recent
\textsc{BaBar} measurement of transition form
factor. The next-to-next-to-leading order (NNLO) perturbative correction to the
form factor, is investigated in the NRQCD
factorization framework for the first time. As a byproduct, we obtain by far
the most precise order- NRQCD matching coefficient for the
process. After including the substantial negative
order- correction, the good agreement between NRQCD prediction and
the measured form factor is completely ruined over a
wide range of momentum transfer squared. This eminent discrepancy casts some
doubts on the applicability of NRQCD approach to hard exclusive reactions
involving charmonium.Comment: 6 pages, 3 figures and 1 table; adding Eqs.(8) and (9) as well as
some references, correcting errors in Table 1, updating Fig.3 to include the
"light-by-light" contributions, devoting a paragraph to discuss why our
strategy of interpreting the NNLO corrections is justified; Accepted by PR
Three-body interactions on a triangular lattice
We analyze the hard-core Bose-Hubbard model with both the three-body and
nearest neighbor repulsions on the triangular lattice. The phase diagram is
achieved by means of the semi-classical approximation and the quantum Monte
Carlo simulation. For a system with only the three-body interactions, both the
supersolid phase and one third solid disappear while the two thirds solid
stably exists. As the thermal behavior of the bosons with nearest neighbor
repulsion, the solid and the superfluid undergo the 3-state Potts and the
Kosterlitz-Thouless type phase transitions, respectively. In a system with both
the frustrated nearest neighbor two-body and three-body interactions, the
supersolid and one third solid revive. By tuning the strength of the three-body
interactions, the phase diagram is distorted, because the one-third solid and
the supersolid are suppressed.Comment: 6 pages, 11 figure
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