1,652 research outputs found
Higgs Boson Decay into a Pair of Leptons
The decay of a Higgs boson into a pair of W bosons h --> W^+W^-, is a
dominant mode for Higgs boson masses above 135 GeV. At hadron colliders,
searches for this decay focus on channels in which both W bosons decay
leptonically into charged leptons, h --> W^+ W^- --> l^+ l^- plus missing
energy. We show that semileptonic decays of heavy flavors are an important
background to this signal. Lepton isolation provides too little suppression of
heavy flavor contributions, and an additional 4 to 8 orders-of-magnitude
suppression must come from physics cuts. An increase of the cut on the the
minimum transverse momentum of non-leading leptons in multilepton events is one
effective way to achieve the needed suppression, without appreciable loss of
the Higgs boson signal.Comment: 4 pages, 2 figures, 1 table. AIP style file. Paper presented by Ed
Berger. To be published in the proceedings of the 9th Conference on the
Intersections of Particle and Nuclear Physics (CIPANP 2006), Rio Grande,
Puerto Rico, May 30-June 3, 200
Isolated leptons from heavy flavor decays: Theory and data
Events with isolated leptons play a prominent role in signatures of new
physics phenomena at high energy collider physics facilities. In earlier
publications, we examine the standard model contribution to isolated lepton
production from bottom and charm mesons and baryons through their semileptonic
decays (b, c -> l + X), showing that this source can overwhelm the effects of
other standard model processes in some kinematic domains. In this paper, we
show that we obtain good agreement with recent Tevatron collider data, both
validating our simulations and showing that we underestimate the magnitude of
the heavy-flavor contribution to the isolated lepton yields. We also show that
the isolation requirement acts as a narrow bandpass filter on the momentum of
the isolated lepton, and we illustrate the effect of this filter on the
background to Higgs boson observation in the dilepton mode. We introduce and
justify a new rule of thumb: isolated electrons and muons from heavy flavor
decay are produced with roughly the same distributions as b and c quarks, but
with 1/200 times the rates of b and c production, respectively.Comment: 12 pg, revtex, 5 fig, corrected typo
Associated Higgs plus vector boson test of a fermiophobic Higgs boson
Production in association with an electroweak vector boson V is a distinctive
mode of production for a Higgs boson H without tree-level couplings to
fermions, known as a fermiophobic Higgs boson. We focus on HV associated
production with H decay into a pair of photons, and V into a pair of jets, with
the goal of distinguishing a fermiophobic Higgs boson from the standard model
Higgs boson. Performing a simulation of the signal and pertinent QCD
backgrounds, and using the same event selection cuts employed by the LHC ATLAS
Collaboration, we argue that existing LHC data at 7 TeV with 4.9 fb^{-1} of
integrated luminosity may distinguish a fermiophobic Higgs boson from a
standard model Higgs boson near 125 GeV at about 1.9 standard deviation signal
significance (1.9 sigma) per experiment. At 8 TeV we show that associated
production could yield 2.8 sigma significance per experiment with 10 fb^{-1} of
data.Comment: 5 pgs., 4 figs, version to appear in Phys. Rev.
Historical Arabic Dialectology: Interpreting the Sources
The description of historical Arabic dialects brings with it a whole plethora of challenges. The most important one is that there are no native speakers left of these dialects, with the consequence that researchers have to rely on written sources in order to discover more about the historical stages of Arabic dialects. These sources are often hard to find and even harder to interpret. This chapter will address some of these challenges, from the interpretation of Arabic orthographical habits in writing the dialect, the use of text editions, and the (un)reliability of historical sources, to the use of Latin transcription or alphabets other than the Arabic for writing the Arabic language. The chapter illustrates these issues with samples of Arabic dialect materials from various periods and origins
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