286 research outputs found
Perturbative QCD effects and the search for a H->WW->l nu l nu signal at the Tevatron
The Tevatron experiments have recently excluded a Standard Model Higgs boson
in the mass range 160 - 170 GeV at the 95% confidence level. This result is
based on sophisticated analyses designed to maximize the ratio of signal and
background cross-sections. In this paper we study the production of a Higgs
boson of mass 160 GeV in the gg -> H -> WW -> l nu l nu channel. We choose a
set of cuts like those adopted in the experimental analysis and compare
kinematical distributions of the final state leptons computed in NNLO QCD to
lower-order calculations and to those obtained with the event generators
PYTHIA, HERWIG and MC@NLO. We also show that the distribution of the output
from an Artificial Neural Network obtained with the different tools does not
show significant differences. However, the final acceptance computed with
PYTHIA is smaller than those obtained at NNLO and with HERWIG and MC@NLO. We
also investigate the impact of the underlying event and hadronization on our
results.Comment: Extra discussion and references adde
The Higgs Sector and CoGeNT/DAMA-Like Dark Matter in Supersymmetric Models
Recent data from CoGeNT and DAMA are roughly consistent with a very light
dark matter particle with m\sim 4-10\gev and spin-independent cross section
of order \sigma_{SI} \sim (1-3)\times 10^{-4}\pb. An important question is
whether these observations are compatible with supersymmetric models obeying
without violating existing collider constraints and
precision measurements. In this talk, I review the fact the the Minimal
Supersymmetric Model allows insufficient flexibility to achieve such
compatibility, basically because of the highly constrained nature of the MSSM
Higgs sector in relation to LEP limits on Higgs bosons. I then outline the
manner in which the more flexible Higgs sectors of the Next-to-Minimal
Supersymmetric Model and an Extended Next-to-Minimal Supersymmetric Model allow
large and at low LSP mass without violating
LEP, Tevatron, BaBar and other experimental limits. The relationship of the
required Higgs sectors to the NMSSM "ideal-Higgs" scenarios is discussed.Comment: 11 pages, 3 figures. To appear in Proceedings of PASCOS 2010. The
paper is a compilation of talks given at: PASCOS 2010, ORSAY Workshop on
"Higgs Hunting", and SLAC Workshop on "Topologies for Early LHC Searches
Combination of Standard Model Higgs searches at CDF
We present the latest combination of searches for a standard model (SM) Higgs
boson in ppbar collisions at \sqrts= 1.96 TeV recorded by the CDF~II detector
at the Fermilab Tevatron. Using data corresponding to 2.3-5.9 fb-1 of
integrated luminosity, we perform searches in a number of different production
and decay modes and then combine them to improve sensitivity. No excess in data
above that expected from backgrounds is observed; therefore, we set upper
limits on the production cross section times branching fraction as a function
of the SM Higgs boson mass (mH). The combined observed (expected) limit is 1.9
(1.8) times the SM prediction at mH = 115 Gev/c^2 and 1.0 (1.1) times the SM
prediction at mH = 165 GeV/c^2.Comment: ICHEP 2010 Conference proceeding, 4 page
Other BSM Searches at the LHC
A review of the discovery potential of LHC for new phenomena beyond the
Standard Model (BSM) other than Supersymmetry in the early phase of running is
presented. Topics covered include searches for extra dimensions in different
scenarios (ADD, Randall-Sundrum, black holes ...), resonance hunting in
di-lepton, di-photon and di-jet final states, searches for contact
interactions, heavy stable charged particles, technicolor, etc. The strategies
of the ATLAS and CMS experiments to understand the detectors and prepare them
for "search" mode and the prospects for discoveries using early data are
described.Comment: 9 pages, 11 figures, Invited LHC review talk at HCP2008, 19th Hadron
Collider Physics Symposium 2008, Galena, IL, USA, May 27-31 200
A radiatively improved fermiophobic Higgs boson scenario
The naive fermiophobic scenario is unstable under radiative corrections, due
to the chiral-symmetry breaking induced by fermion mass terms. In a recent
study, the problem of including the radiative corrections has been tackled via
an effective field theory approach. The renormalized Yukawa couplings are
assumed to vanish at a high energy scale , and their values at the
electroweak scale are computed via modified Renormalization Group Equations. We
show that, in case a fermiophobic Higgs scenario shows up at the LHC, a linear
collider program will be needed to accurately measure the radiative Yukawa
structure, and consequently constrain the scale.Comment: 7 pages, 3 figures, Proceedings of the 2011 International Workshop on
Future Linear Colliders (LCWS11), Granada (Spain), 26-30 September 201
Search for the Standard Model Higgs boson in final states with quarks at the Tevatron
We present the result of searches for a low mass Standard Model Higgs boson
produced in association with a or a boson at a center-of-mass energy of
1.96 TeV with the CDF and D0 detectors at the Fermilab Tevatron
collider. The search is performed in events containing one or two tagged
jets in association with either two leptons, or one lepton and an imbalance in
transverse energy, or simply a large imbalance in transverse energy. Datasets
corresponding to up to 8.5 fb of integrated luminosity are considered in
the analyses. These are the most powerful channels in the search for a low mass
Higgs boson at the Tevatron. Recent sensitivity improvements are discussed. For
a Higgs mass of 115 \gevcc, the expected sensitivity for the most sensitive
individual analyses reaches 2.3 times the SM prediction at 95% confidence level
(C.L.), with all limits below 5 times the SM. Additionally, a
cross-section measurement is performed to validate the analysis techniques
deployed for searching for the Higgs
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