2,878 research outputs found
Lepton Flavor Violation at the LHC
Recent results from Super Kamiokande suggest mixing and
hence lepton flavor violation. In supersymmetric models, this flavor violation
may have implications for the pattern of slepton masses and mixings. Possible
signals for this mixing in the decays of sleptons produced at the LHC are
discussed. The sensitivity expected is compared to that of rare decays such as
.Comment: 14 pages, 9 figure
Scrutinizing LSP Dark Matter at the LHC
We show that LHC experiments might well be able to determine all the
parameters required for a prediction of the present density of thermal LSP
relics from the Big Bang era. If the LSP is an almost pure bino we usually only
need to determine its mass and the mass of the SU(2) singlet sleptons. This
information can be obtained by reconstructing the cascade . The only requirement is that ,
which is true for most of the cosmologically interesting parameter space. If
the LSP has a significant higgsino component, its predicted thermal relic
density is smaller than for an equal--mass bino. We show that in this case
squark decays also produce significant numbers of and
. Reconstructing the corresponding decay cascades then
allows to determine the higgsino component of the LSP
Measurement of the Superparticle Mass Spectrum in the Long-Lived Stau Scenario at the LHC
In supersymmetric scenarios with a long-lived stau, the LHC experiments
provide us with a great environment for precise mass measurements of
superparticles. We study a case in which the mass differences between the
lightest stau and other sleptons are about 10 GeV or larger, so that the decay
products of heavier sleptons are hard enough to be detected. We demonstrate
that the masses of neutralinos, sleptons, and squarks can be measured with a
good accuracy.Comment: 20 pages, 6 figure
Field Theory in Noncommutative Minkowski Superspace
There is much discussion of scenarios where the space-time coordinates x^\mu
are noncommutative. The discussion has been extended to include nontrivial
anticommutation relations among spinor coordinates in superspace. A number of
authors have studied field theoretical consequences of the deformation of N=1
superspace arising from nonanticommutativity of coordinates \theta, while
leaving \bar{theta}'s anticommuting. This is possible in Euclidean superspace
only. In this note we present a way to extend the discussion by making both
\theta and \bar{theta} coordinates non-anticommuting in Minkowski superspace.
We present a consistent algebra for the supercoordinates, find a star-product,
and give the Wess-Zumino Lagrangian L_{WZ} within our model. It has two extra
terms due to non(anti)commutativity. The Lagrangian in Minkowski superspace is
always manifestly Hermitian and for L_{WZ} it preserves Lorentz invariance.Comment: 8 pages, added references, two-column format, published in PR
A Definitive Signal of Multiple Supersymmetry Breaking
If the lightest observable-sector supersymmetric particle (LOSP) is charged
and long-lived, then it may be possible to indirectly measure the Planck mass
at the LHC and provide a spectacular confirmation of supergravity as a symmetry
of nature. Unfortunately, this proposal is only feasible if the gravitino is
heavy enough to be measured at colliders, and this condition is in direct
conflict with constraints from big bang nucleosynthesis (BBN). In this work, we
show that the BBN bound can be naturally evaded in the presence of multiple
sectors which independently break supersymmetry, since there is a new decay
channel of the LOSP to a goldstino. Certain regions of parameter space allow
for a direct measurement of LOSP decays into both the goldstino and the
gravitino at the LHC. If the goldstino/gravitino mass ratio is measured to be
2, as suggested by theory, then this would provide dramatic verification of the
existence of multiple supersymmetry breaking and sequestering. A variety of
consistent cosmological scenarios are obtained within this framework. In
particular, if an R symmetry is imposed, then the gauge-gaugino-goldstino
interaction vertices can be forbidden. In this case, there is no bound on the
reheating temperature from goldstino overproduction, and thermal leptogenesis
can be accommodated consistently with gravitino dark matter.Comment: 10 pages, 5 figures, title changed to match the version published in
JHE
The QCD Coupling Constant
This paper presents a summary of the current status of determinations of the
strong coupling constant alpha_s. A detailed description of the definition,
scale dependence and inherent theoretical ambiguities is given. The various
physical processes that can be used to determine alpha_s are reviewed and
attention is given to the uncertainties, both theoretical and experimental.Comment: 56 page
The Standard Model on Non-Commutative Space-Time: Electroweak Currents and Higgs Sector
In this article we review the electroweak charged and neutral currents in the
Non-Commutative Standard Model (NCSM) and compute the Higgs and Yukawa parts of
the NCSM action. With the aim to make the NCSM accessible to phenomenological
considerations, all relevant expressions are given in terms of physical fields
and Feynman rules are provided.Comment: 33 pages, axodraw.sty; shortened, comments and references added,
version to appear in EPJ
Run Scenarios for the Linear Collider
Scenarios are developed for runs at a Linear Collider, in the case that there
is a rich program of new physics.Comment: 12 pages, 10 tables, Latex; Snowmass 2001 plenary repor
- …