Resonant slepton production at the LHC in models with an ultralight gravitino

We examine resonant slepton production at the LHC with gravitinos in the final state. The slepton undergoes gauge decay into a neutralino and a lepton, the neutralino decays into a photon and a gravitino. By measuring the transverse masses of the gamma- G and the l-gamma- G subsystems it is possible to accurately reconstruct both the slepton and neutralino masses. In some regions of parameter space the slepton decays directly into a lepton and gravitino, giving an identical experimental topology to W production (l missing E_T). We present the novel matrix element squared for lepton-gravitino production. A peak in the tail of the lepton-missing momentum transverse mass distribution of the W provides a signature for the process and an accurate measurement of the slepton mass. We display the search reach for the LHC and 300 fb^{-1} of integrated luminosity.Comment: 13 pages. Minor changes in v

Impact of CMS Multi-jets and Missing Energy Search on CMSSM Fits

Recent CMS data significantly extend the direct search exclusion for supersymmetry. We examine the impact of such data on global fits of the constrained minimal supersymmetric standard model (CMSSM) to indirect and cosmological data. By simulating supersymmetric signal events at the LHC, we construct a likelihood map for the recent CMS data, validating it against the exclusion region calculated by the experiment itself. A previous CMSSM global fit is then re-weighted by our likelihood map. The CMS results nibble away at the high fit probability density region, transforming probability distributions for the scalar and gluino masses. The CMS search has a non-trivial effect on tan beta due to correlations between the parameters implied by the fits to indirect data.Comment: 15 pages, 8 figures. v2 has an appendix added with further checks of A0-tan beta independence, expected sensitivity curves added to Fig 2a and typos fixed. v3 has extended discussion of re-weighting procedure and egregious points in the appendix. v4 minor changes due to very strict (but good) refere

Theoretical Uncertainties in Sparticle Mass Predictions

We contrast the sparticle spectra obtained from three modern publicly available codes along model lines in minimal supersymmetric standard model (MSSM) parameter space. From this we gain an idea of the uncertainties involved with sparticle spectra calculations. The differences in predicted sparticle masses are typically at the several percent-level. In the focus-point scenario, there are differences of 30% in the weak gaugino masses. These uncertainties need to be reduced in order to obtain accurate information about fundamental models of supersymmetry breaking.Comment: revTex4 style. Softsusy homepage is at http://allanach.home.cern.ch/allanach/softsusy.html Written for Snowmass 2001. Replaced version has updated reference. 3 pages, 3 figure

Naturalness Priors and Fits to the Constrained Minimal Supersymmetric Standard Model

We examine the effect of a prior that favours low values of fine-tuning on Bayesian multi-dimensional fits of the constrained minimal supersymmetric standard model (CMSSM or mSUGRA) to current data. The dark matter relic density, the anomalous magnetic moment of the muon and the branching ratio of b->s gamma are all used to constrain the model via a Markov Chain Monte Carlo sampler. As a result of the naturalness prior, posterior probability distributions skew towards lighter higgs and sparticle masses, the effect being most pronounced in the gaugino sector. Interestingly, slepton masses are an exception and skew towards heavier masses. The lightest CP-even Higgs h^0-pole region becomes allowed at the 2 sigma level for the latest combination of measurements of m_t=172.7+/-2.9 GeV, provided we allow for a theoretical error in the prediction of its mass m_{h^0}. m_{h^0} is constrained to be less than 120 GeV at the 95% C.L. Probing the branching ratio of B_s->mu^+ mu^- to the level of 2 x 10^{-8}, as might be achieved by the Tevatron experiments, would cover 32% of the probability density, irrespective of which of the two priors is used.Comment: 15 pages, 5 figures. Ref adde

Multidimensional mSUGRA likelihood maps

We calculate the likelihood map in the full 7 dimensional parameter space of the minimal supersymmetric standard model (MSSM) assuming universal boundary conditions on the supersymmetry breaking terms. Simultaneous variations of m_0, A_0, M_{1/2}, tan beta, m_t, m_b and alpha_s(M_Z) are applied using a Markov chain Monte Carlo algorithm. We use measurements of b -> s gamma, (g-2)_mu and Omega_{DM} h^2 in order to constrain the model. We present likelihood distributions for some of the sparticle masses, for the branching ratio of B_s^0 -> mu^+ mu^- and for m_{stau}-m_{chi_1^0}. An upper limit of 2.10^{-8} on this branching ratio might be achieved at the Tevatron, and would rule out 29% of the currently allowed likelihood. If one allows for non thermal-neutralino components of dark matter, this fraction becomes 35%. The mass ordering allows the important cascade decay squark_L -> chi_2^0 -> slepton_R -> chi_1^0 with a likelihood of 24+/-4%. The stop coannihilation region is highly disfavoured, whereas the light Higgs region is marginally disfavoured

Sampling using a 'bank' of clues

An easy-to-implement form of the Metropolis Algorithm is described which, unlike most standard techniques, is well suited to sampling from multi-modal distributions on spaces with moderate numbers of dimensions (order ten) in environments typical of investigations into current constraints on Beyond-the-Standard-Model physics. The sampling technique makes use of pre-existing information (which can safely be of low or uncertain quality) relating to the distribution from which it is desired to sample. This information should come in the form of a ``bank'' or ``cache'' of space points of which at least some may be expected to be near regions of interest in the desired distribution. In practical circumstances such ``banks of clues'' are easy to assemble from earlier work, aborted runs, discarded burn-in samples from failed sampling attempts, or from prior scouting investigations. The technique equilibrates between disconnected parts of the distribution without user input. The algorithm is not lead astray by ``bad'' clues, but there is no free lunch: performance gains will only be seen where clues are helpful

R-parity Violation and General Soft Supersymmetry Breaking

We consider the most general class possible of soft supersymmetry breaking terms that can be added to the MSSM, with and without R-parity violation, consistent with the sole requirement that no quadratic divergences are induced. We renormalise the resulting theory through one loop and give an example of how a previously ignored term might affect the sparticle spectrum.Comment: 11 pages, 1 figure. Plain TeX, uses Harvmac (Big) and epsf. Added references and typo corrected (v2

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.Comment: Updated to SOFTSUSY3.3.3. Program may be downloaded from http://projects.hepforge.org/softsusy/ and future manuals will be distributed with the cod