1,437 research outputs found
Praising the Enemy: Could the United States Criminalize the Glorification of Terror Under an Act Similar to the United Kingdom\u27s Terrorism Act 2006?
Calculation of W b bbar Production via Double Parton Scattering at the LHC
We investigate the potential to observe double parton scattering at the Large
Hadron Collider in p p -> W b bbar X -> l nu b bbar X at 7 TeV. Our analysis
tests the efficacy of several kinematic variables in isolating the double
parton process of interest from the single parton process and relevant
backgrounds for the first 10 inverse fb of integrated luminosity. These
variables are constructed to expose the independent nature of the two
subprocesses in double parton scattering, pp -> l nu X and pp -> b bbar X. We
use next-to-leading order perturbative predictions for the double parton and
single parton scattering components of W b bbar and for the pertinent
backgrounds. The next-to-leading order contributions are important for a proper
description of some of the observables we compute. We find that the double
parton process can be identified and measured with significance S/sqrt(B) ~ 10,
provided the double parton scattering effective cross section sigma_{eff} ~ 12
mb.Comment: 21 pages, 9 figures; v2: improved presentation and figures, version
published in Phys. Rev.
Higgs-Pair Production and Measurement of the Triscalar Coupling at LHC(8,14)
We simulate the measurement of the triscalar Higgs coupling at LHC(8,14) via
pair production of h(125 GeV). We find that the most promising hh final state
is bb gamma gamma. We account for deviations of the triscalar coupling from its
SM value and study the effects of this coupling on the hh cross-section and
distributions with cut-based and multivariate methods. Our fit to the hh
production matrix element at LHC(14) with 3 ab^-1 yields a 40% uncertainty on
this coupling in the SM and a range of 25-80% uncertainties for non-SM values.Comment: 4 pages, 7 page
Gamma-ray lines and One-Loop Continuum from s-channel Dark Matter Annihilations
The era of indirect detection searches for dark matter has begun, with the
sensitivities of gamma-ray detectors now approaching the parameter space
relevant for weakly interacting massive particles. In particular, gamma ray
lines would be smoking gun signatures of dark matter annihilation, although
they are typically suppressed compared to the continuum. In this paper, we pay
particular attention to the 1-loop continuum generated together with the
gamma-ray lines and investigate under which conditions a dark matter model can
naturally lead to a line signal that is relatively enhanced. We study generic
classes of models in which DM is a fermion that annihilates through an
s-channel mediator which is either a vector or scalar and identify the coupling
and mass conditions under which large line signals occur. We focus on the
"forbidden channel mechanism" advocated a few years ago in the "Higgs in space"
scenario for which tree level annihilation is kinematically forbidden today.
Detailed calculations of all 1-loop annihilation channels are provided. We
single out very simple models with a large line over continuum ratio and
present general predictions for a large range of WIMP masses that are relevant
not only for Fermi and Hess II but also for the next generation of telescopes
such as CTA and Gamma-400. Constraints from the relic abundance, direct
detection and collider bounds are also discussed.Comment: 32 pages, 13 figures; v2: minor clarifications, summary paragraph
added; v3: matches published version, minor clarifications, results unchange
Higgs Boson Search Sensitivity in the Dilepton Decay Mode at and 10 TeV
Prospects for discovery of the standard model Higgs boson are examined at
center of mass energies of and TeV at the CERN Large Hadron Collider.
We perform a simulation of the signal and principal backgrounds for Higgs boson
production and decay in the dilepton mode, finding good agreement
with the ATLAS and CMS collaboration estimates of signal significance at 14 TeV
for Higgs boson masses near ~GeV. At the lower energy of ~TeV,
using the same analysis cuts as these collaborations, we compute expected
signal sensitivities of about standard deviations ('s) at ~GeV in the ATLAS case, and about 3.6~ in the CMS case for
~fb of integrated luminosity. Integrated luminosities of
8~ and 3~ are needed in the ATLAS case at and
~TeV, respectively, for level discovery. In the CMS case, the
numbers are 2~ and 1~ at and ~TeV. Our
different stated expectations for the two experiments arise from the more
restrictive analysis cuts in the CMS case. Recast as exclusion limits, our
results show that with of integrated luminosity at 7~TeV, the
LHC may be able to exclude values in the range 160 to 180~GeV provided no
signal is seen.Comment: 29 pages, 8 figures. New results on estimated discovery reach for
both CMS and ATLAS, as well as exclusion limits, along with comparisons with
Tevatron possibilities. References added
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