3,948 research outputs found
Natural Supersymmetry at the LHC
If the minimal supersymmetric standard model is the solution to the hierarchy
problem, the scalar top quark (stop) and the Higgsino should weigh around the
electroweak scale such as 200 GeV. A low messenger scale, which results in a
light gravitino, is also suggested to suppress the quantum corrections to the
Higgs mass parameters. Therefore the minimal model for natural supersymmetry is
a system with stop/Higgsino/gravitino whereas other superparticles are heavy.
We study the LHC signatures of the minimal system and discuss the discovery
potential and methods for the mass measurements.Comment: 19 pages, 6 figures, 1 tabl
Higgs production with large transverse momentum in hadronic collisions at next-to-leading order
Inclusive associated production of a light Higgs boson (m_H < m_t) with one
jet in pp collisions is studied in next-to-leading order QCD. Transverse
momentum (p_T < 30 GeV) and rapidity distributions of the Higgs boson are
calculated for the LHC in the large top-quark mass limit. It is pointed out
that, as much as in the case of inclusive Higgs production, the K-factor of
this process is large (~1.6) and depends weakly on the kinematics in a wide
range of transverse momentum and rapidity intervals. Our result confirms
previous suggestions that the production channel p+p -> H+jet ->
gamma+gamma+jet gives a measurable signal for Higgs production at the LHC in
the mass range 100-140 GeV, crucial also for the ultimate test of the Minimal
Supersymmetric Standard Model.Comment: 7 pages, 3 eps figures include
Gluino Pair Production at Linear e^+e^- Colliders
We study the potential of high-energy linear colliders for the
production of gluino pairs within the Minimal Supersymmetric Standard Model
(MSSM). In this model, the process is mediated by
quark/squark loops, dominantly of the third generation, where the mixing of
left- and right-handed states can become large. Taking into account realistic
beam polarization effects, photon and -boson exchange, and current mass
exclusion limits, we scan the MSSM parameter space for various
center-of-mass energies to determine the regions, where gluino production
should be visible.Comment: 22 pages, 9 figure
The Reach of the Fermilab Tevatron and CERN LHC for Gaugino Mediated SUSY Breaking Models
In supersymmetric models with gaugino mediated SUSY breaking (inoMSB), it is
assumed that SUSY breaking on a hidden brane is communicated to the visible
brane via gauge superfields which propagate in the bulk. This leads to GUT
models where the common gaugino mass is the only soft SUSY breaking
term to receive contributions at tree level. To obtain a viable phenomenology,
it is assumed that the gaugino mass is induced at some scale beyond the
GUT scale, and that additional renormalization group running takes place
between and as in a SUSY GUT. We assume an SU(5) SUSY GUT above
the GUT scale, and compute the SUSY particle spectrum expected in models with
inoMSB. We use the Monte Carlo program ISAJET to simulate signals within the
inoMSB model, and compute the SUSY reach including cuts and triggers approriate
to Fermilab Tevatron and CERN LHC experiments. We find no reach for SUSY by the
Tevatron collider in the trilepton channel. %either with or without %identified
tau leptons. At the CERN LHC, values of (1160) GeV can be probed
with 10 (100) fb of integrated luminosity, corresponding to a reach in
terms of of 2150 (2500) GeV. The inoMSB model and mSUGRA can likely
only be differentiated at a linear collider with sufficient energy to
produce sleptons and charginos.Comment: 17 page revtex file with 9 PS figure
Reconstruction of mass at the LHC
The cascade mass reconstruction approach was used for mass reconstruction of
the lightest stau produced at the LHC in the cascade decay . The stau mass was reconstructed assuming
that masses of gluino, bottom squark and two lightest neutralinos were
reconstructed in advance.
SUSY data sample sets for the SU3 model point containing 160k events each
were generated which corresponded to an integrated luminosity of about at 14 TeV. These events were passed through the AcerDET detector
simulator, which parametrized the response of a generic LHC detector. The mass
of the was reconstructed with a precision of about 20% on
average.Comment: 13 pages, 4 figures, corrected Table 6 and typos, added references
for section
Phase transition and anomalous electronic behavior in layered dichalcogenide CuS (covellite) probed by NQR
Nuclear quadrupole resonance (NQR) on copper nuclei has been applied for
studies of the electronic properties of quasi-two-dimensional low-temperature
superconductor CuS (covellite) in the temperature region between 1.47 and 290
K. Two NQR signals corresponding to two non-equivalent sites of copper in the
structure, Cu(1) and Cu(2), has been found. The temperature dependences of
copper quadrupole frequencies, line-widths and spin-lattice relaxation rates,
which so far had never been investigated so precisely for this material,
altogether demonstrate the structural phase transition near 55 K, which
accompanies transformations of electronic spectrum not typical for simple
metals. The analysis of NQR results and their comparison with literature data
show that the valence of copper ions at both sites is intermediate in character
between monovalent and divalent states with the dominant of the former. It has
been found that there is a strong hybridization of Cu(1) and Cu(2) conduction
bands at low temperatures, indicating that the charge delocalization between
these ions takes place even in 2D regime. Based on our data, the occurrence of
energy gap, charge fluctuations and charge-density waves, as well as the nature
of phase transition in CuS are discussed. It is concluded that some physical
properties of CuS are similar to those of high-temperature superconductors
(HTSC) in normal state.Comment: to be publishe
MSSM Higgs bosons associated with high-pT jets at hadron colliders
The cross section for the production of the lightest neutral Higgs boson in
association with a high-pT hadronic jet, calculated in the framework of the
minimal supersymmetric standard model (MSSM), is presented. The expectations
for the hadronic cross section at the Large Hadron Collider are discussed using
reasonable kinematical cuts. In particular the contributions from superpartner
loops to the cross section and their dependence on the parameters of the MSSM
are investigated and found to be significant. Comparisons show that the
production rate for h0 + jet in the MSSM can differ widely from the
corresponding standard-model prediction.Comment: 20 page
Tevatron-for-LHC Report: Preparations for Discoveries
This is the "TeV4LHC" report of the "Physics Landscapes" Working Group,
focused on facilitating the start-up of physics explorations at the LHC by
using the experience gained at the Tevatron. We present experimental and
theoretical results that can be employed to probe various scenarios for physics
beyond the Standard Model.Comment: 222 pp., additional contribution added, typos/layout correcte
Hidden SUSY at the LHC: the light higgsino-world scenario and the role of a lepton collider
While the SUSY flavor, CP and gravitino problems seem to favor a very heavy
spectrum of matter scalars, fine-tuning in the electroweak sector prefers low
values of superpotential mass \mu. In the limit of low \mu, the two lightest
neutralinos and light chargino are higgsino-like. The light charginos and
neutralinos may have large production cross sections at LHC, but since they are
nearly mass degenerate, there is only small energy release in three-body
sparticle decays. Possible dilepton and trilepton signatures are difficult to
observe after mild cuts due to the very soft p_T spectrum of the final state
isolated leptons. Thus, the higgsino-world scenario can easily elude standard
SUSY searches at the LHC. It should motivate experimental searches to focus on
dimuon and trimuon production at the very lowest p_T(\mu) values possible. If
the neutralino relic abundance is enhanced via non-standard cosmological dark
matter production, then there exist excellent prospects for direct or indirect
detection of higgsino-like WIMPs. While the higgsino-world scenario may easily
hide from LHC SUSY searches, a linear e^+e^- collider or a muon collider
operating in the \sqrt{s}\sim 0.5-1 TeV range would be able to easily access
the chargino and neutralino pair production reactions.Comment: 20 pages including 12 .eps figure
Summary of the SUSY Working Group of the 1999 Les Houches Workshop
The results obtained by the Working Group on Supersymmetry at the 1999 Les
Houches Workshop on Collider Physics are summarized. Separate chapters treat
"general" supersymmetry, R-parity violation, gauge mediated supersymmetry
breaking, and anomaly mediated supersymmetry breaking.Comment: LaTeX, 110 pages with numerous .ps and .eps files. proc.tex is main
tex fil
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