24,183 research outputs found
Resolving the Degeneracy in Single Higgs Production with Higgs Pair Production
The Higgs boson production can be affected by several anomalous couplings,
e.g. and anomalous couplings. Precise measurement of
production yields two degenerate parameter spaces of and ; one
parameter space exhibits the SM limit while the other does not. Such a
degeneracy could be resolved by Higgs boson pair production. In this work we
adapt the strategy suggested by the ATLAS collaboration to explore the
potential of distinguishing the degeneracy at the 14 TeV LHC. If the
anomalous coupling is induced only by the operator , then the non-SM-like band could be excluded with an integrated luminosity
of . Making use of the fact that the Higgs boson pair
is mainly produced through an -wave scattering, we propose an analytical
function to describe the fraction of signal events surviving a series of
experimental cuts for a given invariant mass of Higgs boson pair. The function
is model independent and can be applied to estimate the discovery potential of
various NP models
production and suppression in high energy proton-nucleus collisions
We apply a Color Glass Condensate+Non-Relativistic QCD (CGC+NRQCD) framework
to compute production in deuteron-nucleus collisions at RHIC and
proton-nucleus collisions at the LHC. Our results match smoothly at high
to a next-to-leading order perturbative QCD + NRQCD computation.
Excellent agreement is obtained for spectra at RHIC and LHC for
central and forward rapidities, as well as for the normalized ratio of
these results to spectra in proton-proton collisions. In particular, we observe
that the data is strongly bounded by our computations of the same for
each of the individual NRQCD channels; this result provides strong evidence
that our description is robust against uncertainties in initial conditions and
hadronization mechanisms.Comment: 7 pages, 4 figure
Fragmentation functions of polarized heavy quarkonium
Study of the polarized heavy quarkonium production in recently proposed QCD
factorization formalism requires knowledge of a large number of input
fragmentation functions (FFs) from a single parton or a heavy quark-antiquark
pair to a polarized heavy quarkonium. In this paper, we calculate these FFs at
the input scale in terms of nonrelativistic QCD (NRQCD) factorization. We
derive all relevant polarized NRQCD long-distance matrix elements based
symmetries and propose a self-consistent scheme to define them in arbitrary
dimensions. We then calculate polarized input FFs contributed from all -wave
and -wave NRQCD intermediate states. With our calculation of the polarized
input FFs, and the partonic hard part available in literatures, the QCD
factorization formalism is ready to be applied to polarized heavy quarkonium
production.Comment: 30 pages, 1 figur
Simple non-Abelian extensions of the standard model gauge group and the diboson excesses at the LHC
The ATLAS collaboration reported excesses at around 2 TeV in the di-boson
production decaying into hadronic final states. We consider the possibility of
explaining the excesses with extra gauge bosons in two simple non-Abelian
extensions of the Standard Model. One is the so-called models with a
symmetry structure of and the other is
the models with an extended symmetry of . The and bosons emerge after the electroweak symmetry is
spontaneously broken. Two patterns of symmetry breaking in the models
are considered in this work: one is , the other is . The symmetry breaking of the model is
. We perform a global
analysis of and phenomenology in ten new physics models,
including all the channels of decay. Our study shows that
the leptonic mode and the dijet mode of decays impose a
very stringent bound on the parameter space in several new physics models. Such
tight bounds provide a useful guide for building new physics models to address
on the diboson anomalies. We also note that the Left-Right and Lepton-Phobic
models can explain the excess if the deviation in
the pair around 2~TeV were confirmed to be a fluctuation of the SM
backgrounds.Comment: Publish version; title changed as suggested by journal Edito
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