arXiv subjects

M. A. Bernhardt

Publications and source records attributed to M. A. Bernhardt.

5 recordsLinked to original sources

arXiv2012

Including R-parity violation in the numerical computation of the spectrum of the minimal supersymmetric standard model: SOFTSUSY

Current publicly available computer programs calculate the spectrum and couplings of the minimal supersymmetric standard model under the assumption of R-parity conservation. Here, we describe an extension to the SOFTSUSY program which includes R-parity violating effects. The user provides a theoretical boundary condition upon the high-scale supersymmetry breaking R-parity violating couplings. Successful radiative electroweak symmetry breaking, electroweak and CKM matrix data are used as weak-scale boundary conditions. The renormalisation group equations are solved numerically between the weak scale and a high energy scale using a nested iterative algorithm. This paper serves as a manual to the R-parity violating mode of the program, detailing the approximations and conventions used.

hep-ph↗

arXiv2008

Sneutrino as Lightest Supersymmetric Particle in B3 mSUGRA Models and Signals at the LHC

We consider B3 mSUGRA models where we have one lepton number violating LQD operator at the GUT scale. This can alter the supersymmetric mass spectrum leading to a sneutrino as the lightest supersymmetric particle in a large region of parameter space. We take into account the restrictions from neutrino masses, the muon anomalous magnetic moment, b -> s gamma and other precision measurements. We furthermore investigate existing restrictions from direct searches at LEP, the Tevatron and the CERN p\bar p collider. We then give examples for characteristic signatures at the LHC.

hep-ph↗

arXiv2008

Single Slepton Production in association with a single Top Quark at the Tevatron and LHC

We calculate the total cross section for single charged slepton production in association with a top quark at hadron colliders in the baryon triality (B$_3$) supersymmetric model. We compute event rates for the Tevatron and LHC. We study the signatures for different supersymmetric scenarios including neutralino and stau LSPs. We perform a detailed analysis with basic cuts for the B$_3$ operator $\lam^\prime_{231}$ using Monte Carlo simulations to show that the signal can be distinguished from the background at the LHC. In particular we employ the resulting lepton charge asymmetry.

hep-ph↗

arXiv2007

R-Parity violating minimal supergravity at the LHC

We consider the case where supersymmetry with broken R-parity is embedded in the minimal supergravity model (mSUGRA). This alters the standard mSUGRA spectrum and opens a wide range in parameter space, where the scalar tau is the lightest supersymmetric particle, instead of the lightest neutralino. We study the resulting LHC phenomenology. Promising signatures would be detached vertices from long-lived staus, multi lepton final states and multi-tau final states. We investigate in detail the corresponding cross sections and decay rates in characteristic benchmark scenarios.

hep-ph↗

arXiv2007

Mass Spectrum in R-Parity Violating mSUGRA and Benchmark Points

We investigate in detail the low-energy spectrum of the R-parity violating mSUGRA model using the computer program \texttt{SOFTSUSY}. We impose the experimental constraints from the measurement of the anomalous magnetic moment of the muon, $(g-2)_μ$, the decay $b\ra sγ$ as well as the mass bounds from direct searches at colliders, in particular on the Higgs boson and the lightest chargino. We also include a new calculation for the R parity violating contribution to $\Br(B_s\ra μ^+μ^-)$. We then focus on cases where the lightest neutralino is {\em not} the lightest supersymmetric particle (LSP). In this region of parameter space either the lightest scalar tau (stau) or the scalar tau neutrino (tau sneutrino) is the LSP. We suggest four benchmark points with typical spectra and novel collider signatures for detailed phenomenological analysis and simulation by the LHC collaborations.

hep-ph↗