No Arabic abstract
We consider a specific class of events of the SUSY particle production at the LHC without missing p_T. Namely, we discuss the chargino pair production with a further decay into the W-boson and the neutralino when the masses of the chargino and neutralino differ by 80-90 GeV. In this case, in the final state one has two Ws and missing E_T but no missing P_T. The produced neutralinos are just boosted along Ws. For a demonstration we consider the MSSM with non-universal gaugino masses. In this case, such events are quite probable in the region of parameter space where the lightest chargino and neutralino are mostly gauginos. The excess in the W production cross-section reach about 10 % over the Standard Model background. We demonstrate that the LHC experiments, which presently measure the WW production cross section at the 8 % level can probe chargino mass around 110 GeV within the suggested scenario, which is not accessible via other searches. If the precision of WW cross section measurement at the LHC will achieve the 3 % level, then it would probe chargino masses up to about 150 GeV within the no missing P_T scenario.
We have examined the capability of the LHC, running at both 7 and 8 TeV, to explore the 19(20)-dimensional parameter space of the pMSSM with neutralino(gravitino) LSPs and soft masses up to 4 TeV employing the ATLAS SUSY analysis suite. Here we present some preliminary results for the gravitino model set, following the ATLAS analyses whose data were publically available as of mid-September 2012. We find that the impact of the reduced MET, resulting from models with gravitino LSPs on sparticle searches is more than off-set by the detectability of the many possible long-lived NLSPs.
Recent results on MSSM Higgs physics at the LHC are reviewed. The dependence of the LHC discovery reach in the bbar b H/A, H/A to tau^+tau^- channel on the underlying SUSY scenario is analysed. This is done by combining the latest results for the prospective CMS experimental sensitivities for an integrated luminosity of 30 or 60 fb^-1 with state-of-the-art theoretical predictions of MSSM Higgs-boson properties. The results are interpreted in terms of the parameters governing the MSSM Higgs sector at lowest order, M_A and tan_beta. While the higgsino mass parameter mu has a significant impact on the prospective discovery reach (and correspondingly the ``LHC wedge region), it is found that the discovery reach is rather stable with respect to variations of other supersymmetric parameters. Within the discovery region a determination of the masses of the heavy neutral Higgs bosons with an accuracy of 1-4% seems feasible. It is furthermore shown that Higgs-boson production in central exclusive diffractive channels can provide important information on the properties of the neutral MSSM Higgs bosons.
We give detailed predictions for diffractive SUSY Higgs boson and top squark associated productions at the LHC via the exclusive double pomeron exchange mechanism. We study how the SUSY Higgs cross section and the signal over background ratio are enhanced as a function of tangent beta in different regimes. The prospects are particularly promising in the ``anti-decoupling regime, which we study in detail. We also give the prospects for a precise measurement of the top squark mass using the threshold scan of central diffractive associated top squark events at the LHC.
In this work we analyze the reliability of several techniques for computing jet and hadron spectra at different collision energies. This is of particular relevance for discovering energy loss in the upcoming oxygen-oxygen (OO) run at the LHC, for which a reference $pp$ run at the same energy is currently not planned. For hadrons and jets we compute the ratio of spectra between different $pp$ collision energies in perturbative QCD, which can be used to construct a $pp$ reference spectrum. Alternatively, a $pp$ reference can be interpolated from measured spectra at nearby energies. We estimate the precision and accuracy of both strategies for the spectra ratio relevant to the oxygen run, and conclude that the central values agree to 4% accuracy for hadrons and 2% accuracy for jets. As an alternative, we propose taking the ratio of OO and $pp$ spectra at different collision energies, which cleanly separates the experimental measurement from the theoretical computation.
Phenomenological Tsallis fits to the CMS and ATLAS transverse spectra of charged particles were found to extend for p_T from 0.5 to 181 GeV in pp collisions at LHC at sqrt{s}=7 TeV, and for p_T from 0.5 to 31 GeV at sqrt{s}=0.9 TeV. The simplicity of the Tsallis parametrization and the large range of the fitting transverse momentum raise questions on the physical meaning of the degrees of freedom that enter into the Tsallis distribution or q-statistics.