17,250 research outputs found
SUSY-QCD Corrections to Dark Matter Annihilation in the Higgs Funnel
We compute the full O(alpha_s) SUSY-QCD corrections to dark matter
annihilation in the Higgs-funnel, resumming potentially large mu tan beta and
A_b contributions and keeping all finite O(m_b,s,1/tan^2 beta) terms. We
demonstrate numerically that these corrections strongly influence the
extraction of SUSY mass parameters from cosmological data and must therefore be
included in common analysis tools such as DarkSUSY or micrOMEGAs.Comment: 4 pages, 3 (partly color) figures, version to be published in PR
Flavour Violation in Gauge-Mediated Supersymmetry Breaking Models: Experimental Constraints and Phenomenology at the LHC
We present an extensive analysis of gauge-mediated supersymmetry breaking
models with minimal and non-minimal flavour violation. We first demonstrate
that low-energy, precision electroweak, and cosmological constraints exclude
large "collider-friendly" regions of the minimal parameter space. We then
discuss various possibilities how flavour violation, although naturally
suppressed, may still occur in gauge-mediation models. The introduction of
non-minimal flavour violation at the electroweak scale is shown to relax the
stringent experimental constraints, so that benchmark points, that are also
cosmologically viable, can be defined and their phenomenology, i.e. squark and
gaugino production cross sections with flavour violation, at the LHC can be
studied.Comment: 29 pages, 1 table, 27 figures. Minor changes. Version published in
Nucl. Phys.
Squark and Gaugino Hadroproduction and Decays in Non-Minimal Flavour Violating Supersymmetry
We present an extensive analysis of squark and gaugino hadroproduction and
decays in non-minimal flavour violating supersymmetry. We employ the so-called
super-CKM basis to define the possible misalignment of quark and squark
rotations, and we use generalized (possibly complex) charges to define the
mutual couplings of (s)quarks and gauge bosons/gauginos. The cross sections for
all squark-(anti-)squark/gaugino pair and squark-gaugino associated production
processes as well as their decay widths are then given in compact analytic
form. For four different constrained supersymmetry breaking models with
non-minimal flavour violation in the second/third generation squark sector
only, we establish the parameter space regions allowed/favoured by low-energy,
electroweak precision, and cosmological constraints and display the chirality
and flavour decomposition of all up- and down-type squark mass eigenstates.
Finally, we compute numerically the dependence of a representative sample of
production cross sections at the LHC on the off-diagonal mass matrix elements
in the experimentally allowed/favoured ranges.Comment: 35 pages, 29 (partly colour) figures. Some typos corrected, wording
of several paragraphs improved, version accepted by Nucl. Phys.
Statistical Laws and Mechanics of Voronoi Random Lattices
We investigate random lattices where the connectivities are determined by the
Voronoi construction, while the location of the points are the dynamic degrees
of freedom. The Voronoi random lattices with an associated energy are immersed
in a heat bath and investigated using a Monte Carlo simulation algorithm. In
thermodynamic equilibrium we measure coordination number distributions and test
the Aboav-Weaire and Lewis laws.Comment: 14 pages (figures not included), LaTeX, HLRZ-26/9
SUSY-QCD corrections to stop annihilation into electroweak final states including Coulomb enhancement effects
We present the full supersymmetric QCD corrections
for stop-anti-stop annihilation into electroweak final states within the
Minimal Supersymmetric Standard Model (MSSM). We also incorporate Coulomb
corrections due to gluon exchange between the incoming stops. Numerical results
for the annihilation cross sections and the predicted neutralino relic density
are presented. We show that the impact of the radiative corrections on the
cosmologically preferred region of the parameter space can become larger than
the current experimental uncertainty, shifting the relic bands within the
considered regions of the parameter space by up to a few tens of GeV.Comment: 20 pages, 13 figures, updated to version published in Phys. Rev.
Discrete Fracture Model with Anisotropic Load Sharing
A two-dimensional fracture model where the interaction among elements is
modeled by an anisotropic stress-transfer function is presented. The influence
of anisotropy on the macroscopic properties of the samples is clarified, by
interpolating between several limiting cases of load sharing. Furthermore, the
critical stress and the distribution of failure avalanches are obtained
numerically for different values of the anisotropy parameter and as a
function of the interaction exponent . From numerical results, one can
certainly conclude that the anisotropy does not change the crossover point
in 2D. Hence, in the limit of infinite system size, the crossover
value between local and global load sharing is the same as the one
obtained in the isotropic case. In the case of finite systems, however, for
, the global load sharing behavior is approached very slowly
One-loop corrections to gaugino (co-)annihilation into quarks in the MSSM
We present the full supersymmetric QCD corrections
for gaugino annihilation and co-annihilation into light and heavy quarks in the
Minimal Supersymmetric Standard Model (MSSM). We demonstrate that these
channels are phenomenologically relevant within the so-called phenomenological
MSSM. We discuss selected technical details such as the dipole subtraction
method in the case of light quarks and the treatment of the bottom quark mass
and Yukawa coupling. Numerical results for the (co-)annihilation cross sections
and the predicted neutralino relic density are presented. We show that the
impact of including the radiative corrections on the cosmologically preferred
region of the parameter space is larger than the current experimental
uncertainty from Planck data.Comment: 19 pages, 9 figures. Matches version published in Phys.Rev.
Break-up of shells under explosion and impact
A theoretical and experimental study of the fragmentation of closed thin
shells made of a disordered brittle material is presented. Experiments were
performed on brown and white hen egg-shells under two different loading
conditions: fragmentation due to an impact with a hard wall and explosion by a
combustion mixture giving rise to power law fragment size distributions. For
the theoretical investigations a three-dimensional discrete element model of
shells is constructed. Molecular dynamics simulations of the two loading cases
resulted in power law fragment mass distributions in satisfactory agreement
with experiments. Based on large scale simulations we give evidence that power
law distributions arise due to an underlying phase transition which proved to
be abrupt and continuous for explosion and impact, respectively. Our results
demonstrate that the fragmentation of closed shells defines a universality
class different from that of two- and three-dimensional bulk systems.Comment: 11 pages, 14 figures in eps forma
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