3,973 research outputs found
Finding the Leptonic Decay Mode of a Heavy Higgs Boson
We reanalyze the extraction of the heavy Higgs boson signal from the
Standard Model background at hadron supercolliders, taking into account revised
estimates of the top quark background. With new acceptance criteria the
detection of the signal remains viable. Requiring a forward jet-tag, a central
jet-veto, and a large relative transverse momentum of the two charged leptons
yields for one year of running at the SSC or LHC.Comment: LaTex(Revtex), 9 pages, 6 figures (available upon request),
MAD/PH/75
H-->WW as the discovery mode for a light Higgs boson
The production cross section for a m_H=115 GeV, SM Higgs boson in weak boson
fusion at the LHC is sizable. However, the branching fraction for H-->WW is
expected to be relatively small. The signal, with its two forward jets, is
sufficiently different from the main backgrounds that a signal to background
ratio of better than 1:1 can nevertheless be obtained, with large enough rate
to allow for a 5 sigma signal with 35 fb^{-1} of data. The H-->WW signal in
weak boson fusion may thus prove to be the discovery mode for the Higgs boson
at the LHC.Comment: 10 pages, 4 figures, uses revte
Searching for Stoponium along with the Higgs boson
Stoponium, a bound state of top squark and its antiparticle in a
supersymmetric model, may be found in the ongoing Higgs searches at the LHC.
Its WW and ZZ detection ratios relative to the Standard Model Higgs boson can
be more than unity from WW* threshold to the two Higgs threshold. The gamma
gamma channel is equally promising. Some regions of the stoponium mass below
150 GeV are already being probed by the ATLAS and CMS experiments.Comment: 10 pages 5 figure
Which long-baseline neutrino experiments are preferable?
We discuss the physics of superbeam upgrades, where we focus on T2KK, a NuMI
beam line based experiment NOvA*, and a wide band beam (WBB) experiment
independent of the NuMI beam line. For T2KK, we find that the Japan-Korea
baseline helps resolve parameter degeneracies, but the improvement due to
correlated systematics between the two detectors (using identical detectors) is
only moderate. For an upgrade of NOvA with a liquid argon detector, we
demonstrate that the Ash River site is preferred compared to alternatives, such
as at the second oscillation maximum, and is the optimal site within the U.S.
For a WBB experiment, we find that high proton energies and long decay tunnels
are preferable. We compare water Cherenkov and liquid argon technologies, and
find the break-even point in detector cost at about 4:1. In order to compare
the physics potential of the different experimental configurations, we use the
concept of exposure to normalize the performance. We find that experiments with
WBBs are the best experimental concept. NOvA* could be competitive with
sufficient luminosity. If > 0.01, a WBB experiment can
perform better than a neutrino factory.Comment: 31 pages, 13 figures, 5 tables. Version to appear in PR
Searching for a heavy Higgs boson via the H --> l nu jj decay mode at the CERN LHC
The discovery of a heavy Higgs boson with mass up to m_H = 1 TeV at the CERN
LHC is possible in the H--> W^+W^- --> l nu jj decay mode. The weak boson
scattering signal and backgrounds from t\bar tjj and from W+jets production are
analyzed with parton level Monte Carlo programs which are built on full tree
level amplitudes for all subprocesses. The use of double jet tagging and the
reconstruction of the W invariant mass reduce the combined backgrounds to the
same level as the Higgs signal. A central mini-jet veto, which distinguishes
the different gluon radiation patterns of the hard processes, further improves
the signal to background ratio to about 2.5:1, with a signal cross section of 1
fb. The jet energy asymmetry of the W --> jj decay will give a clear signature
of the longitudinal polarization of the W's in the final event sample.Comment: 23 pages (with 7 embedded figures), Revtex, uses epsf.sty.
Z-compressed postscript version also available at
http://phenom.physics.wisc.edu/pub/preprints/1997/madph-97-1017.ps.Z or at
ftp://phenom.physics.wisc.edu/pub/preprints/1997/madph-97-1017.ps.
Rise of Kp Total Cross Section and Universality
The increase of the measured hadronic total cross sections at the highest
energies is empirically described by squared log of center-of-mass energy sqrt
s as sigma(tot)= B (log s)2, consistent with the energy dependence of the
Froissart unitarity bound. The coefficient B is argued to have a universal
value, but this is not proved directly from QCD. In the previous tests of this
universality, the p(pbar)p, pi p, and K p forward scatterings were analyzed
independently and found to be consistent with B(pp) = B(pip) = B(Kp), although
the determined value of B(Kp) had large uncertainty. In the present work, we
have further analyzed forward Kp scattering to obtain a more exact value of
B(Kp). Making use of continuous moment sum rules(CMSR) we have fully exploited
the information of low-energy scattering data to predict the high-energy
behavior of the amplitude hrough duality. The estimation of B(Kp) is improved
remarkably, and our result strongly supports the universality of B.Comment: 12 pages, 3 figure
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