7,252 research outputs found
Search for SUSY in (Leptons +) Jets + E_T^miss final states
We study the observability of the squarks and gluinos in CMS at LHC.
Classical E_T^miss + jets final state as well as a number of additional
multilepton signatures (0 leptons, 1 lepton, 2 leptons of the same sign, 2
leptons of the opposite sign and 3 leptons) are investigated . The detection of
these sparticles relies on the observation of an excess of events over Standard
Model background expectations. The study is made in the framework of a minimal
SU(5) mSUGRA model as a function of m_0, m_1/2 for 4 sets of model parameters :
tan(beta) = 2 or 35 and sign(mu) = +/- 1 and for fixed value of A_0 = 0. The
CMS detector response is modelled using CMSJET 4.51 fast MC code (non-GEANT).
The results obtained are presented as 5 sigma detection contours in the m_0,
m_1/2 planes and with optimized selection cuts in various regions of the
parameter space. The result of these investigations is that with integrated
luminosity L=10^5 pb^-1 the squark and gluino mass reach is about 2.5 TeV and
covers most of the interesting parts of parameter space according to neutralino
relic density expectations. The influence of signal and background
cross-section uncertainties on the reach contours is estimated. The effect of
pile-up on signal and background is also discussed. This effect is found to be
insignificant for E_T^miss and single lepton signatures, whilst only a minor
deterioration is seen for multilepton final states.Comment: 28 pages, 28 figure
Recharge unit provides for optimum recharging of battery cells
Percent recharge unit permits each cell of a rechargeable battery to be charged to a preset capacity of the cell. The unit automatically monitors and controls a rechargeable battery subjected to charge-discharge cycling tests
Land-surface influences on weather and climate
Land-surface influences on weather and climate are reviewed. The interrelationship of vegetation, evapotranspiration, atmospheric circulation, and climate is discussed. Global precipitation, soil moisture, the seasonal water cycle, heat transfer, and atmospheric temperature are among the parameters considered in the context of a general biosphere model
Implications of Compressed Supersymmetry for Collider and Dark Matter Searches
Martin has proposed a scenario dubbed ``compressed supersymmetry'' (SUSY)
where the MSSM is the effective field theory between energy scales M_{\rm weak}
and M_{\rm GUT}, but with the GUT scale SU(3) gaugino mass M_3<< M_1 or M_2. As
a result, squark and gluino masses are suppressed relative to slepton, chargino
and neutralino masses, leading to a compressed sparticle mass spectrum, and
where the dark matter relic density in the early universe may be dominantly
governed by neutralino annihilation into ttbar pairs via exchange of a light
top squark. We explore the dark matter and collider signals expected from
compressed SUSY for two distinct model lines with differing assumptions about
GUT scale gaugino mass parameters. For dark matter signals, the compressed
squark spectrum leads to an enhancement in direct detection rates compared to
models with unified gaugino masses. Meanwhile, neutralino halo annihilation
rates to gamma rays and anti-matter are also enhanced relative to related
scenarios with unified gaugino masses but, depending on the halo dark matter
distribution, may yet be below the sensitivity of indirect searches underway.
In the case of collider signals, we compare the rates for the potentially
dominant decay modes of the stop_1 which may be expected to be produced in
cascade decay chains at the LHC: \tst_1\to c\tz_1 and \tst_1\to bW\tz_1. We
examine the extent to which multilepton signal rates are reduced when the
two-body decay mode dominates. For the model lines that we examine here, the
multi-lepton signals, though reduced, still remain observable at the LHC.Comment: 22 pages including 24 eps figure
Large-scale collective properties of self-propelled rods
We study, in two space dimensions, the large-scale properties of collections
of constant-speed polar point particles interacting locally by nematic
alignment in the presence of noise. This minimal approach to self-propelled
rods allows one to deal with large numbers of particles, revealing a
phenomenology previously unseen in more complicated models, and moreover
distinctively different from both that of the purely polar case (e.g. the
Vicsek model) and of active nematics.Comment: Submitted to Phys. Rev. Let
Supersymmetry discovery potential of the LHC at 10 and 14 TeV without and with missing
We examine the supersymmetry (SUSY) reach of the CERN LHC operating at
and 14 TeV within the framework of the minimal supergravity
model. We improve upon previous reach projections by incorporating updated
background calculations including a variety of Standard Model (SM)
processes. We show that SUSY discovery is possible even before the detectors
are understood well enough to utilize either or electrons in
the signal. We evaluate the early SUSY reach of the LHC at TeV by
examining multi-muon plus jets and also dijet events with {\it no}
missing cuts and show that the greatest reach in terms of
occurs in the dijet channel. The reach in multi-muons is slightly smaller in
, but extends to higher values of . We find that an observable
multi-muon signal will first appear in the opposite-sign dimuon channel, but as
the integrated luminosity increases the relatively background-free but
rate-limited same-sign dimuon, and ultimately the trimuon channel yield the
highest reach. We show characteristic distributions in these channels that
serve to distinguish the signal from the SM background, and also help to
corroborate its SUSY origin. We then evaluate the LHC reach in various
no-lepton and multi-lepton plus jets channels {\it including} missing
cuts for and 14 TeV, and plot the reach for integrated
luminosities ranging up to 3000 fb at the SLHC. For TeV,
the LHC reach extends to and 2.9 TeV for
and integrated luminosities of 10, 100, 1000 and
3000 fb, respectively. For TeV, the LHC reach for the same
integrated luminosities is to m_{gluino}=2.4,\3.1, 3.7 and 4.0 TeV.Comment: 34 pages, 25 figures. Revised projections for the SUSY reach for
ab^-1 integrated luminosities, with minor corrections of references and text.
2 figures added. To appear in JHE
Reach of the Fermilab Tevatron for minimal supergravity in the region of large scalar masses
The reach of the Fermilab Tevatron for supersymmetric matter has been
calculated in the framework of the minimal supergravity model in the clean
trilepton channel. Previous analyses of this channel were restricted to scalar
masses m_0<= 1 TeV. We extend the analysis to large values of scalar masses
m_0\sim 3.5 TeV. This includes the compelling hyperbolic branch/focus point
(HB/FP) region, where the superpotential \mu parameter becomes small. In this
region, assuming a 5\sigma (3\sigma) signal with 10 (25) fb^{-1} of integrated
luminosity, the Tevatron reach in the trilepton channel extends up to
m_{1/2}\sim 190 (270) GeV independent of \tan\beta . This corresponds to a
reach in terms of the gluino mass of m_{\tg}\sim 575 (750) GeV.Comment: 11 page latex file including 6 EPS figures; several typos corrected
and references adde
On the Mapping of Time-Dependent Densities onto Potentials in Quantum Mechanics
The mapping of time-dependent densities on potentials in quantum mechanics is
critically examined. The issue is of significance ever since Runge and Gross
(Phys. Rev. Lett. 52, 997 (1984)) established the uniqueness of the mapping,
forming a theoretical basis for time-dependent density functional theory. We
argue that besides existence (so called v-representability) and uniqueness
there is an important question of stability and chaos. Studying a 2-level
system we find innocent, almost constant densities that cannot be constructed
from any potential (non-existence). We further show via a Lyapunov analysis
that the mapping of densities on potentials has chaotic regions in this case.
In real space the situation is more subtle. V-representability is formally
assured but the mapping is often chaotic making the actual construction of the
potential almost impossible. The chaotic nature of the mapping, studied for the
first time here, has serious consequences regarding the possibility of using
TDDFT in real-time settings
Supersymmetry Reach of Tevatron Upgrades: The Large Case
The Yukawa couplings of the tau lepton and the bottom quark become comparable
to, or even exceed, electroweak gauge couplings for large values of the SUSY
parameter . As a result, the lightest tau slepton \ttau_1 and
bottom squark \tb_1 can be significantly lighter than corresponding sleptons
and squarks of the first two generations. Gluino, chargino and neutralino
decays to third generation particles are significantly enhanced when
is large. This affects projections for collider experiment reach
for supersymmetric particles. In this paper, we evaluate the reach of the
Fermilab Tevatron collider for supersymmetric signals in the
framework of the mSUGRA model. We find that the reach via signatures with
multiple isolated leptons ( and ) is considerably reduced. For very
large , the greatest reach is attained in the multi-jet+\eslt
signature. Some significant extra regions may be probed by requiring the
presence of an identified -jet in jets+\eslt events, or by requiring one
of the identified leptons in clean trilepton events to actually be a hadronic 1
or 3 charged prong tau. In an appendix, we present formulae for chargino,
neutralino and gluino three body decays which are valid at large .Comment: 31 page Revtex file including 10 PS figure
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