The Status of Supersymmetry after the LHC Run 1

Supersymmetry (SUSY) is a complete and renormalisable candidate for an extension of the Standard Model. At an energy scale not too far above the electroweak scale it would solve the hierarchy problem of the SM Higgs boson, dynamically explain electroweak symmetry breaking, and provide a dark-matter candidate. Since it doubles the Standard Model degrees of freedom, SUSY predicts a large number of additional particles, whose properties and effects on precision measurements can be explicitly predicted in a given SUSY model. In this review the motivation for SUSY is outlined, the various searches strategies for SUSY particles at the LHC are described, and the status of SUSY in global analyses after the LHC Run 1 is summarized.

Constrained Supersymmetry after two years of LHC data: a global view with Fittino

We perform global fits to the parameters of the Constrained Minimal Supersymmetric Standard Model (CMSSM) and to a variant with non-universal Higgs masses (NUHM1). In addition to constraints from low-energy precision observables and the cosmological dark matter density, we take into account the LHC exclusions from searches in jets plus missing transverse energy signatures with about 5,fb$^{-1}$ of integrated luminosity. We also include the most recent upper bound on the branching ratio $B_stomumu$ from LHCb. Furthermore, constraints from and implications for direct and indirect dark matter searches are discussed. The best fit of the CMSSM prefers a light Higgs boson just above the experimentally excluded mass. We find that the description of the low-energy observables, $(g-2)_{mu}$ in particular, and the non-observation of SUSY at the LHC become more and more incompatible within the CMSSM. A potential SM-like Higgs boson with mass around 126 GeV can barely be accommodated. Values for ${cal B}(B_stomumu)$ just around the Standard Model prediction are naturally expected in the best fit region. The most-preferred region is not yet affected by limits on direct WIMP searches, but the next generation of experiments will probe this region. Finally, we discuss implications from fine-tuning for the best fit regions.

Present and possible future implications for mSUGRA of the non-discovery of SUSY at the LHC

Both ATLAS and CMS have published results of SUSY searches putting limits on SUSY parameters and masses. A non-discovery of SUSY in the next two years would push these limits further. On the other hand, precision data of low energy measurements and the dark matter relic density favor a light scale of supersymmetry. Therefore we investigate if supersymmetry -- more specifically the highly constraint model mSUGRA -- does at all agree with precision data and LHC exclusions at the same time, and whether the first two years of LHC will be capable of excluding models of supersymmetry. We consider the current non observation of supersymmetry with 35 pb-1 as well as the possible non observation with 1,2 and 7 fb-1 in a global fit using the framework Fittino.

Constraining SUSY models with Fittino using measurements before, with and beyond the LHC

We investigate the constraints on Supersymmetry arising from available precision measurements using a global fit approach. When interpreted within minimal supergravity (mSUGRA), the data provide significant constraints on the masses of supersymmetric particles, which are predicted to be light enough for an early discovery at the Large Hadron Collider (LHC). We provide predicted mass spectra including, for the first time, full uncertainty bands. The most stringent constraint is from the measurement of the anomalous magnetic moment of the muon. Using the results of these fits, we investigate to which precision mSUGRA and more general MSSM parameters can be measured by the LHC experiments with three different integrated luminosities for a parameter point which approximately lies in the region preferred by current data. The impact of the already available measurements on these precisions, when combined with LHC data, is also studied. We develop a method to treat ambiguities arising from different interpretations of the data within one model and provide a way to differentiate between values of different digital parameters of a model. Finally, we show how measurements at a linear collider with up to 1 TeV centre-of-mass energy will help to improve precision by an order of magnitude.

Radiative $bto d$ Penguins

This article gives an overview of the recent searches and measurements of $bto d$ penguin transitions with the BaBar experiment. The branching fraction of these decays in the Standard Model (SM) is expected to be a factor of 10 or more lower than the corresponding $bto s$ penguin transitions, but a deviation from the SM prediction would be an equally striking sign of new physics. The exclusive decay $Btopiellell$ is searched by BaBar with no excess over the background found. The BaBar measurement of $Bto(rho,omega)gamma$ provides the first evidence of $B^+torho^+gamma$, is in good agreement with the previous Belle results and provides a measurement of $|V_{td}/V_{ts}|$ independent of the one from $B_s$ mixing. No deviation from the SM is found.