618 research outputs found
MSSM Dark Matter Without Prejudice
Recently we examined a large number of points in a 19-dimensional parameter
subspace of the CP-conserving MSSM with Minimal Flavor Violation. We determined
whether each of these points satisfied existing theoretical, experimental, and
observational constraints. Here we discuss the properties of the parameter
space points allowed by existing data that are relevant for dark matter
searches.Comment: 4 pages, 3 figs; talk given at SUSY0
Vector unparticle contributions to lepton g-2
The generic unparticle propagator may be modified in two ways. Breaking the
conformal symmetry effectively adds a mass term to the propagator, while
considering vacuum polarization corrections adds a width-like term. Both of
these modifications result naturally from the coupling of the unparticle to
standard model (SM) fields. We explore how these modifications to the
propagator affect the calculation of the lepton anomalous magnetic moment using
an integral approximation of the propagator that is accurate for
, where is the unparticle dimension. We find that for this
range of and various values of the conformal breaking scale , the
value of calculated when allowing various SM fermions to run in the
unparticle self-energy loops does not significantly deviate from the value of
when the width term is ignored. We also investigate the limits on a
characteristic mass scale for the unparticle sector as a function of and
.Comment: 16 pages, 11 figures, 2 tables. Included neutrinos in loops. Added
reference
The Hierarchy Solution to the LHC Inverse Problem
Supersymmetric (SUSY) models, even those described by relatively few
parameters, generically allow many possible SUSY particle (sparticle) mass
hierarchies. As the sparticle mass hierarchy determines, to a great extent, the
collider phenomenology of a model, the enumeration of these hierarchies is of
the utmost importance. We therefore provide a readily generalizable procedure
for determining the number of sparticle mass hierarchies in a given SUSY model.
As an application, we analyze the gravity-mediated SUSY breaking scenario with
various combinations of GUT-scale boundary conditions involving different
levels of universality among the gaugino and scalar masses. For each of the
eight considered models, we provide the complete list of forbidden hierarchies
in a compact form. Our main result is that the complete (typically rather
large) set of forbidden hierarchies among the eight sparticles considered in
this analysis can be fully specified by just a few forbidden relations
involving much smaller subsets of sparticles.Comment: 44 pages, 2 figures. Python code providing lists of allowed and
forbidden hierarchy is included in ancillary file
Edge Detecting New Physics the Voronoi Way
We point out that interesting features in high energy physics data can be
determined from properties of Voronoi tessellations of the relevant phase
space. For illustration, we focus on the detection of kinematic "edges" in two
dimensions, which may signal physics beyond the standard model. After deriving
some useful geometric results for Voronoi tessellations on perfect grids, we
propose several algorithms for tagging the Voronoi cells in the vicinity of
kinematic edges in real data. We show that the efficiency is improved by the
addition of a few Voronoi relaxation steps via Lloyd's method. By preserving
the maximum spatial resolution of the data, Voronoi methods can be a valuable
addition to the data analysis toolkit at the LHC.Comment: 6 pages, 7 figure
Exploring Theory Space with Monte Carlo Reweighting
Theories of new physics often involve a large number of unknown parameters
which need to be scanned. Additionally, a putative signal in a particular
channel may be due to a variety of distinct models of new physics. This makes
experimental attempts to constrain the parameter space of motivated new physics
models with a high degree of generality quite challenging. We describe how the
reweighting of events may allow this challenge to be met, as fully simulated
Monte Carlo samples generated for arbitrary benchmark models can be effectively
re-used. In particular, we suggest procedures that allow more efficient
collaboration between theorists and experimentalists in exploring large theory
parameter spaces in a rigorous way at the LHC.Comment: 30 pages, 10 figures. Corresponds to published version. Additional
discussion of uncertainties vis-\`a-vis v
The Matrix Element Method: Past, Present, and Future
The increasing use of multivariate methods, and in particular the Matrix
Element Method (MEM), represents a revolution in experimental particle physics.
With continued exponential growth in computing capabilities, the use of
sophisticated multivariate methods-- already common-- will soon become
ubiquitous and ultimately almost compulsory. While the existence of
sophisticated algorithms for disentangling signal and background might naively
suggest a diminished role for theorists, the use of the MEM, with its inherent
connection to the calculation of differential cross sections will benefit from
collaboration between theorists and experimentalists. In this white paper, we
will briefly describe the MEM and some of its recent uses, note some current
issues and potential resolutions, and speculate about exciting future
opportunities.Comment: 3 pages, no figures. Snowmass white paper. Minor revisions.
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