9,907 research outputs found
Higgs Boson Production via Gluon Fusion in the Standard Model with four Generations
Higgs bosons can be produced copiously at the LHC via gluon fusion induced by
top and bottom quark loops, and can be enhanced strongly if extra heavy quarks
exist. We present results for Higgs +zero-, one- and two-jet production at the
LHC, in both the Standard Model and the 4th generation model, by evaluating the
corresponding heavy quark triangle, box and pentagon Feynman diagrams. We
compare the results by using the effective Higgs-gluon interactions in the
limit of heavy quarks with the cross sections including the full mass
dependences. NLO effects with full mass dependence are included in the
inclusive Higgs boson production rate. Our results improve the theoretical
basis for fourth generation effects on the Higgs boson search at the LHC.Comment: Published version in PR
Transverse momentum resummation in soft-collinear effective theory
We present a universal formalism for transverse momentum resummation in the
view of soft-collinear effective theory (SCET), and establish the relation
between our SCET formula and the well known Collins-Soper-Sterman's pQCD
formula at the next-to-leading logarithmic order (NLLO). We also briefly
discuss the reformulation of joint resummation in SCET.Comment: 23 pages, 7 figures; version to appear in Phys. Rev.
Search for anomalous top quark production at the early LHC
We present a detailed study of the anomalous top quark production with
subsequent decay at the LHC induced by model-independent flavor-changing
neutral-current couplings, incorporating the complete next-to-leading order QCD
effects. Our results show that, taking into account the current limits from the
Tevatron, the LHC with TeV may discover the anomalous coupling at
5 level for a very low integrated luminosity of 61 pb. The
discovery potentials for the anomalous couplings at the LHC are examined in
detail. We also discuss the possibility of using the charge ratio to
distinguish the and couplings.Comment: 4 pages, 3 figures, version appears in Phys. Rev. Let
Top-Quark Decay at Next-to-Next-to-Leading Order in QCD
We present the complete calculation of the top-quark decay width at
next-to-next-to-leading order in QCD, including next-to-leading electroweak
corrections as well as finite bottom quark mass and boson width effects. In
particular, we also show the first results of the fully differential decay
rates for top-quark semileptonic decay at
next-to-next-to-leading order in QCD. Our method is based on the understanding
of the invariant mass distribution of the final-state jet in the singular limit
from effective field theory. Our result can be used to study arbitrary
infrared-safe observables of top-quark decay with the highest perturbative
accuracy.Comment: 5 pages, 6 figures; version accepted for publication in Physical
Review Letter
SU(5) Symmetry of spdfg Interacting Boson Model
The extended interacting boson model with s-, p-, d-, f- and g-bosons being
included (spdfg IBM) are investigated. The algebraic structure including the
generators, the Casimir operators of the groups at the SU(5) dynamical symmetry
and the branching rules of the irreducible representation reductions along the
group chain are obtained. The typical energy spectrum of the Symmetry is given.Comment: 12 pages, 2 figure
Next-to-leading order QCD effects in associated charged Higgs and W boson production in the MSSM at the CERN Large Hadron Collider
We present the calculations of the next-to-leading order (NLO) QCD
corrections to the inclusive total cross sections for the associated production
of the through annihilation in the Minimal
Supersymmetric Standard Model at the CERN Large Hadron Collider. The NLO QCD
corrections can either enhance or reduce the total cross sections, but they
generally efficiently reduce the dependence of the total cross sections on the
renormalization/factorization scale. The magnitude of the NLO QCD corrections
is about 10% in most of the parameter space and can reach 15% in some parameter
regions. We also show the Monte Carlo simulation results for the
signature from the and the
decays including the NLO QCD effects, and find an observable signal at a
level in some parameter region of the minimal supergravity model.Comment: version to be published in Phys.Rev.
Next-to-leading order QCD corrections to associated production via the flavor-changing neutral-current couplings at hadron colliders
We present the complete next-to-leading order (NLO) QCD corrections to
associated production induced by the model-independent and
flavor-changing neutral-current couplings at hadron colliders, respectively.
Our results show that, for the coupling the NLO QCD corrections can
enhance the total cross sections by about 60% and 42%, and for the
coupling by about 51% and 43% at the Tevatron and LHC, respectively. The NLO
corrections, for the couplings, can enhance the total cross sections by
about 27%, and by about 42% for the coupling at the LHC. We also consider
the mixing effects between the and couplings for this process,
which can either be large or small depending on the values of the anomalous
couplings. Besides, the NLO corrections reduce the dependence of the total
cross sections on the renormalization or factorization scale significantly,
which lead to increased confidence on the theoretical predictions. And we also
evaluate the NLO corrections to several important kinematic distributions.Comment: Published version in Phys. Rev.
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