Likelihood Functions for Supersymmetric Observables in Frequentist Analyses of the CMSSM and NUHM1

On the basis of frequentist analyses of experimental constraints from electroweak precision data, g-2, B physics and cosmological data, we investigate the parameters of the constrained MSSM (CMSSM) with universal soft supersymmetry-breaking mass parameters, and a model with common non-universal Higgs masses (NUHM1). We present chi^2 likelihood functions for the masses of supersymmetric particles and Higgs bosons, as well as b to s gamma, b to mu mu and the spin-independent dark matter scattering cross section. In the CMSSM we find preferences for sparticle masses that are relatively light. In the NUHM1 the best-fit values for many sparticle masses are even slightly smaller, but with greater uncertainties. The likelihood functions for most sparticle masses are cut off sharply at small masses, in particular by the LEP Higgs mass constraint. Both in the CMSSM and the NUHM1, the coannihilation region is favoured over the focus-point region at about the 3-sigma level, largely but not exclusively because of g-2. Many sparticle masses are highly correlated in both the CMSSM and NUHM1, and most of the regions preferred at the 95% C.L. are accessible to early LHC running. Some slepton and chargino/neutralino masses should be in reach at the ILC. The masses of the heavier Higgs bosons should be accessible at the LHC and the ILC in portions of the preferred regions in the (M_A, tan beta) plane. In the CMSSM, the likelihood function for b to mu mu is peaked close to the Standard Model value, but much larger values are possible in the NUHM1. We find that values of the DM cross section > 10^{-10} pb are preferred in both the CMSSM and the NUHM1. We study the effects of dropping the g-2, b to s gamma, relic density and M_h constraints.Comment: 34 pages, 24 figure

Implications of LHC Searches on SUSY Particle Spectra: The pMSSM Parameter Space with Neutralino Dark Matter

We study the implications of LHC searches on SUSY particle spectra using flat scans of the 19-parameter pMSSM phase space. We apply constraints from flavour physics, g_mu-2, dark matter and earlier LEP and Tevatron searches. The sensitivity of the LHC SUSY searches with jets, leptons and missing energy is assessed by reproducing with fast simulation the recent CMS analyses after validation on benchmark points. We present results in terms of the fraction of pMSSM points compatible with all the constraints which are excluded by the LHC searches with 1 fb^{-1} and 15 fb^{-1} as a function of the mass of strongly and weakly interacting SUSY particles. We also discuss the suppression of Higgs production cross sections for the MSSM points not excluded and contrast the region of parameter space tested by the LHC data with the constraints from dark matter direct detection experiments.Comment: 14 pages, 13 figures. v2: increased statistics, to appear in EPJ

WMAP-Compliant Benchmark Surfaces for MSSM Higgs Bosons

We explore `benchmark surfaces' suitable for studying the phenomenology of Higgs bosons in the minimal supersymmetric extension of the Standard Model (MSSM), which are chosen so that the supersymmetric relic density is generally compatible with the range of cold dark matter density preferred by WMAP and other observations. These benchmark surfaces are specified assuming that gaugino masses m_{1/2}, soft trilinear supersymmetry-breaking parameters A_0 and the soft supersymmetry-breaking contributions m_0 to the squark and slepton masses are universal, but not those associated with the Higgs multiplets (the NUHM framework). The benchmark surfaces may be presented as M_A-tan_beta planes with fixed or systematically varying values of the other NUHM parameters, such as m_0, m_{1/2}, A_0 and the Higgs mixing parameter mu. We discuss the prospects for probing experimentally these benchmark surfaces at the Tevatron collider, the LHC, the ILC, in B physics and in direct dark-matter detection experiments. An Appendix documents developments in the FeynHiggs code that enable the user to explore for her/himself the WMAP-compliant benchmark surfaces.Comment: Minor corrections, references added. 43 pages, 10 figures. Version to appear in JHE

Revisiting the Higgs Mass and Dark Matter in the CMSSM

Taking into account the available accelerator and astrophysical constraints, the mass of the lightest neutral Higgs boson h in the minimal supersymmetric extension of the Standard Model with universal soft supersymmetry-breaking masses (CMSSM) has been estimated to lie between 114 and ~ 130 GeV. Recent data from ATLAS and CMS hint that m_h ~ 125 GeV, though m_h ~ 119 GeV may still be a possibility. Here we study the consequences for the parameters of the CMSSM and direct dark matter detection if the Higgs hint is confirmed, focusing on the strips in the (m_1/2, m_0) planes for different tan beta and A_0 where the relic density of the lightest neutralino chi falls within the range of the cosmological cold dark matter density allowed by WMAP and other experiments. We find that if m_h ~ 125 GeV focus-point strips would be disfavoured, as would the low-tan beta stau-chi and stop -chi coannihilation strips, whereas the stau-chi coannihilation strip at large tan beta and A_0 > 0 would be favoured, together with its extension to a funnel where rapid annihilation via direct-channel H/A poles dominates. On the other hand, if m_h ~ 119 GeV more options would be open. We give parametrizations of WMAP strips with large tan beta and fixed A_0/m_0 > 0 that include portions compatible with m_h = 125 GeV, and present predictions for spin-independent elastic dark matter scattering along these strips. These are generally low for models compatible with m_h = 125 GeV, whereas the XENON100 experiment already excludes some portions of strips where m_h is smaller.Comment: 24 pages, 9 figure

Electroweak Supersymmetry around the Electroweak Scale

Inspired by the phenomenological constraints, LHC supersymmetry and Higgs searches, dark matter search as well as string model building, we propose the electroweak supersymmetry around the electroweak scale: the squarks and/or gluinos are around a few TeV while the sleptons, sneutrinos, bino and winos are within one TeV. The Higgsinos can be either heavy or light. We consider bino as the dominant component of dark matter candidate, and the observed dark matter relic density is achieved via the neutralino-stau coannihilations. Considering the Generalized Minimal Supergravity (GmSUGRA), we show explicitly that the electroweak supersymmetry can be realized, and the gauge coupling unification can be preserved. With two Scenarios, we study the viable parameter spaces that satisfy all the current phenomenological constraints, and we present the concrete benchmark points. Furthermore, we comment on the fine-tuning problem and LHC searches.Comment: RevTex4, 28 pages, 8 figures, 8 tables, version to appear in EPJ

On the detectability of the CMSSM light Higgs boson at the Tevatron

We examine the prospects of detecting the light Higgs h^0 of the Constrained MSSM at the Tevatron. To this end we explore the CMSSM parameter space with \mu>0, using a Markov Chain Monte Carlo technique, and apply all relevant collider and cosmological constraints including their uncertainties, as well as those of the Standard Model parameters. Taking 50 GeV < m_{1/2}, m_0 < 4 TeV, |A_0| < 7 TeV and 2 < tan(beta) < 62 as flat priors and using the formalism of Bayesian statistics we find that the 68% posterior probability region for the h^0 mass lies between 115.4 GeV and 120.4 GeV. Otherwise, h^0 is very similar to the Standard Model Higgs boson. Nevertheless, we point out some enhancements in its couplings to bottom and tau pairs, ranging from a few per cent in most of the CMSSM parameter space, up to several per cent in the favored region of tan(beta)\sim 50 and the pseudoscalar Higgs mass of m_A\lsim 1 TeV. We also find that the other Higgs bosons are typically heavier, although not necessarily much heavier. For values of the h^0 mass within the 95% probability range as determined by our analysis, a 95% CL exclusion limit can be set with about 2/fb of integrated luminosity per experiment, or else with 4/fb (12/fb) a 3 sigma evidence (5 sigma discovery) will be guaranteed. We also emphasize that the alternative statistical measure of the mean quality-of-fit favors a somewhat lower Higgs mass range; this implies even more optimistic prospects for the CMSSM light Higgs search than the more conservative Bayesian approach. In conclusion, for the above CMSSM parameter ranges, especially m_0, either some evidence will be found at the Tevatron for the light Higgs boson or, at a high confidence level, the CMSSM will be ruled out.Comment: JHEP versio

Gravitino Dark Matter Scenarios with Massive Metastable Charged Sparticles at the LHC

We investigate the measurement of supersymmetric particle masses at the LHC in gravitino dark matter (GDM) scenarios where the next-to-lightest supersymmetric partner (NLSP) is the lighter scalar tau, or stau, and is stable on the scale of a detector. Such a massive metastable charged sparticle would have distinctive Time-of-Flight (ToF) and energy-loss ($dE/dx$) signatures. We summarise the documented accuracies expected to be achievable with the ATLAS detector in measurements of the stau mass and its momentum at the LHC. We then use a fast simulation of an LHC detector to demonstrate techniques for reconstructing the cascade decays of supersymmetric particles in GDM scenarios, using a parameterisation of the detector response to staus, taus and jets based on full simulation results. Supersymmetric pair-production events are selected with high redundancy and efficiency, and many valuable measurements can be made starting from stau tracks in the detector. We recalibrate the momenta of taus using transverse-momentum balance, and use kinematic cuts to select combinations of staus, taus, jets and leptons that exhibit peaks in invariant masses that correspond to various heavier sparticle species, with errors often comparable with the jet energy scale uncertainty.Comment: 23 pages, 10 figures, updated to version published in JHE

Gravitational Collapse of Null Radiation and a String fluid

We consider the end state of collapsing null radiation with a string fluid. It is shown that, if diffusive transport is assumed for the string, that a naked singularity can form (at least locally). The model has the advantage of not being asymptotically flat. We also analyse the case of a radiation-string two-fluid and show that a locally naked singularity can result in the collapse of such matter. We contrast this model with that of strange quark matter.Comment: RevTeX 4.0 (8 pages - no figures). submitted to Phys Rev D. Some changes to abstract, introduction and conclusion - references update

Classical and quantum properties of a 2-sphere singularity

Recently Boehmer and Lobo have shown that a metric due to Florides, which has been used as an interior Schwarzschild solution, can be extended to reveal a classical singularity that has the form of a two-sphere. Here the singularity is shown to be a scalar curvature singularity that is both timelike and gravitationally weak. It is also shown to be a quantum singularity because the Klein-Gordon operator associated with quantum mechanical particles approaching the singularity is not essentially self-adjoint.Comment: 10 pages, 1 figure, minor corrections, final versio

Jet angular correlation in vector-boson fusion processes at hadron colliders

Higgs boson and massive-graviton productions in association with two jets via vector-boson fusion (VBF) processes and their decays into a vector-boson pair at hadron colliders are studied. They include scalar and tensor boson production processes via weak-boson fusion in quark-quark collisions, gluon fusion in quark-quark, quark-gluon and gluon-gluon collisions, as well as their decays into a pair of weak bosons or virtual gluons which subsequently decay into $\ell\bar\ell$, $q\bar q$ or $gg$. We give the helicity amplitudes explicitly for all the VBF subprocesses, and show that the VBF amplitudes dominate the exact matrix elements not only for the weak-boson fusion processes but also for all the gluon fusion processes when appropriate selection cuts are applied, such as a large rapidity separation between two jets and a slicing cut for the transverse momenta of the jets. We also show that our off-shell vector-boson current amplitudes reduce to the standard quark and gluon splitting amplitudes with appropriate gluon-polarization phases in the collinear limit. Nontrivial azimuthal angle correlations of the jets in the production and in the decay of massive spin-0 and -2 bosons are manifestly expressed as the quantum interference among different helicity states of the intermediate vector-bosons. Those correlations reflect the spin and the CP nature of the Higgs bosons and the massive gravitons.Comment: 47 pages, 7 figures, 10 tables; references added, version to appear in JHE