216 research outputs found
Sparticle Mass Spectra from SO(10) Grand Unified Models with Yukawa Coupling Unification
We examine the spectrum of superparticles obtained from the minimal SO(10)
grand unified model, where it is assumed the gauge symmetry breaking yields the
Minimal Supersymmetric Standard Model (MSSM) as the effective theory at
GeV. In this model, unification of Yukawa
couplings implies a value of . At such high values of
, assuming universality of scalar masses, the usual mechanism of
radiative electroweak symmetry breaking breaks down. We show that a set of weak
scale sparticle masses consistent with radiative electroweak symmetry breaking
can be generated by imposing non-universal GUT scale scalar masses consistent
with universality within SO(10) plus extra -term contributions associated
with the reduction in rank of the gauge symmetry group when SO(10)
spontaneously breaks to . We comment upon the
consequences of the sparticle mass spectrum for collider searches for
supersymmetry. One implication of SO(10) unification is that the light bottom
squark can be by far the lightest of the squarks. This motivates a dedicated
search for bottom squark pair production at and colliders.Comment: 12 page REVTEX file including 3 PS figures; revised manuscript
includes minor changes to coincide with published versio
Predictors of Progress in Smoking Cessation
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71613/1/j.1525-1446.1995.tb00143.x.pd
Sneutrino-induced like sign dilepton signal with conserved R-parity
Lepton number violation could be manifest in the sneutrino sector of
supersymmetric extensions of the standard model with conserved R-parity. Then
sneutrinos decay partly into the ``wrong sign charged lepton'' final state, if
kinematically accessible. In sneutrino pair production or associated single
sneutrino production, the signal then is a like sign dilepton final state.
Under favourable circumstances, such a signal could be visible at the LHC or a
next generation linear collider for a relative sneutrino mass-splitting of
order and sneutrino width of order (1 GeV). On the
other hand, the like sign dilepton event rate at the TEVATRON is probably too
small to be observable.Comment: 19 pages, 14 Figures. Section about LSD at LHC and TEVATRON added.
Previous Title "Single sneutrino production and the wrong charged lepton
signal
Dark Matter, Light Stops and Electroweak Baryogenesis
We examine the neutralino relic density in the presence of a light top
squark, such as the one required for the realization of the electroweak
baryogenesis mechanism, within the minimal supersymmetric standard model. We
show that there are three clearly distinguishable regions of parameter space,
where the relic density is consistent with WMAP and other cosmological data.
These regions are characterized by annihilation cross sections mediated by
either light Higgs bosons, Z bosons, or by the co-annihilation with the
lightest stop. Tevatron collider experiments can test the presence of the light
stop in most of the parameter space. In the co-annihilation region, however,
the mass difference between the light stop and the lightest neutralino varies
between 15 and 30 GeV, presenting an interesting challenge for stop searches at
hadron colliders. We present the prospects for direct detection of dark matter,
which provides a complementary way of testing this scenario. We also derive the
required structure of the high energy soft supersymmetry breaking mass
parameters where the neutralino is a dark matter candidate and the stop
spectrum is consistent with electroweak baryogenesis and the present bounds on
the lightest Higgs mass.Comment: 24 pages, 8 figures; version published in Phys.Rev.
Electric charge quantization and the muon anomalous magnetic moment
We investigate some proposals to solve the electric charge quantization
puzzle, which simultaneously explain the recent measured deviation on the muon
anomalous magnetic moment. For this we assess extensions of the Electro-Weak
Standard Model spanning modifications on the scalar sector only. It is
interesting to verify that one can have modest extensions which easily account
for the solution for both problems.Comment: 20 pages, 1 figures, needs macro axodraw.st
Top-squark searches at the Tevatron in models of low-energy supersymmetry breaking
We study the production and decays of top squarks (stops) at the Tevatron
collider in models of low-energy supersymmetry breaking. We consider the case
where the lightest Standard Model (SM) superpartner is a light neutralino that
predominantly decays into a photon and a light gravitino. Considering the
lighter stop to be the next-to-lightest Standard Model superpartner, we analyze
stop signatures associated with jets, photons and missing energy, which lead to
signals naturally larger than the associated SM backgrounds. We consider both
2-body and 3-body decays of the top squarks and show that the reach of the
Tevatron can be significantly larger than that expected within either the
standard supergravity models or models of low-energy supersymmetry breaking in
which the stop is the lightest SM superpartner. For a modest projection of the
final Tevatron luminosity, L = 4 fb-1, stop masses of order 300 GeV are
accessible at the Tevatron collider in both 2-body and 3-body decay modes. We
also consider the production and decay of ten degenerate squarks that are the
supersymmetric partners of the five light quarks. In this case we find that
common squark masses up to 360 GeV are easily accessible at the Tevatron
collider, and that the reach increases further if the gluino is light.Comment: 32 pages, 9 figures; references adde
Muon anomalous magnetic moment, lepton flavor violation, and flavor changing neutral current processes in SUSY GUT with right-handed neutrino
Motivated by the large mixing angle solutions for the atmospheric and solar
neutrino anomalies, flavor changing neutral current processes and lepton flavor
violating processes as well as the muon anomalous magnetic moment are analyzed
in the framework of SU(5) SUSY GUT with right-handed neutrino. In order to
explain realistic mass relations for quarks and leptons, we take into account
effects of higher dimensional operators above the GUT scale. It is shown that
the supersymmetric (SUSY) contributions to the CP violation parameter in
mixing, , the branching ratio,
and the muon anomalous magnetic moment become large in a wide range of
parameter space. We also investigate correlations among these quantities.
Within the current experimental bound of , large
SUSY contributions are possible either in the muon anomalous magnetic moment or
in . In the former case, the favorable value of the recent muon
anomalous magnetic moment measurement at the BNL E821 experiment can be
accommodated. In the latter case, the allowed region of the Kobayashi-Maskawa
phase can be different from the prediction within the Standard Model (SM) and
therefore the measurements of the CP asymmetry of mode and
could discriminate this case from the SM. We also show that
the branching ratio can be close to the current
experimental upperbound and the mixing induced CP asymmetry of the radiative B
decay can be enhanced in the case where the neutrino parameters correspond to
the Mikheyev-Smirnov-Wolfenstein small mixing angle solution.Comment: 70 pages, 14 figure
Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX collaboration
Extensive experimental data from high-energy nucleus-nucleus collisions were
recorded using the PHENIX detector at the Relativistic Heavy Ion Collider
(RHIC). The comprehensive set of measurements from the first three years of
RHIC operation includes charged particle multiplicities, transverse energy,
yield ratios and spectra of identified hadrons in a wide range of transverse
momenta (p_T), elliptic flow, two-particle correlations, non-statistical
fluctuations, and suppression of particle production at high p_T. The results
are examined with an emphasis on implications for the formation of a new state
of dense matter. We find that the state of matter created at RHIC cannot be
described in terms of ordinary color neutral hadrons.Comment: 510 authors, 127 pages text, 56 figures, 1 tables, LaTeX. Submitted
to Nuclear Physics A as a regular article; v3 has minor changes in response
to referee comments. Plain text data tables for the points plotted in figures
for this and previous PHENIX publications are (or will be) publicly available
at http://www.phenix.bnl.gov/papers.htm
Point absorbers in Advanced LIGO
Published 30 April 2021Small, highly absorbing points are randomly present on the surfaces of the main interferometer optics in Advanced LIGO. The resulting nanometer scale thermo-elastic deformations and substrate lenses from these micron-scale absorbers significantly reduce the sensitivity of the interferometer directly though a reduction in the power-recycling gain and indirect interactions with the feedback control system. We review the expected surface deformation from point absorbers and provide a pedagogical description of the impact on power buildup in second generation gravitational wave detectors (dual-recycled Fabry-Perot Michelson interferometers). This analysis predicts that the power-dependent reduction in interferometer performance will significantly degrade maximum stored power by up to 50% and, hence, limit GW sensitivity, but it suggests system wide corrections that can be implemented in current and future GW detectors. This is particularly pressing given that future GW detectors call for an order of magnitude more stored power than currently used in Advanced LIGO in Observing Run 3. We briefly review strategies to mitigate the effects of point absorbers in current and future GW wave detectors to maximize the success of these enterprises.Aidan F. Brooks ... Daniel D. Brown ... Huy Tuong Cao ... Alexei A. Ciobanu ... David J. Ottaway ... Peter J. Veitch ... et al
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