A Heavy Higgs and a Light Sneutrino NLSP in the MSSM with Enhanced SU(2) D-terms
The Minimal Supersymmetric extension of the Standard Model provides a solution to the hierarchy problem and leads to the presence of a light Higgs. A Higgs boson with mass above the present experimental bound may only be obtained for relatively heavy third generation squarks, requiring a precise, somewhat unnatural balance between different contributions to the effective Higgs mass parameter. It was recently noticed that somewhat heavier Higgs bosons, which are naturally beyond the LEP bound, may be obtained by enhanced weak SU(2) Dterms. Such contributions appear in models with an enhanced electroweak gauge symmetry, provided the supersymmetry breaking masses associated with the scalars responsible for the breakdown of the enhanced gauge symmetry group to the Standard Model one, are larger than the enhanced symmetry breaking scale. In this article we emphasize that the enhanced SU(2) D-terms will not only raise the Higgs boson mass but also affect the spectrum of the nonstandard Higgs bosons, sleptons and squarks, which therefore provide a natural contribution to the T parameter, compensating for the negative one coming from the heavy Higgs boson. The sleptons and non-standard Higgs bosons of these models, in particular, may act in a way similar to the so-called inert Higgs doublet. The phenomenological properties of these models are emphasized and possible cosmological implications as well as collider signatures are described.

title: Indirect probes of the MSSM after the Higgs discovery
abstract: A bstractWe study the minimal supersymmetric standard model (MSSM) with minimal flavor violation (MFV), imposing constraints from flavor physics observables and MSSM Higgs searches, in light of the recent discovery of a 125 GeV Higgs boson by ATLAS and CMS. We analyze the electroweak vacuum stability conditions to further restrict the MSSM parameter space. In addition, a connection to ultraviolet physics is shown via an implementation of renormalization group running, which determines the TeV-scale spectrum from a small set of minimal supergravity parameters. Finally, we investigate the impact from dark matter direct detection searches. Our work highlights the complementarity of collider, flavor and dark matter probes in exploring the MSSM, and shows that even in a MFV framework, flavor observables constrain the MSSM parameter space well beyond the current reach of direct SUSY particle searches.

title: Vacuum stability and Higgs diphoton decays in the MSSM
abstract: A bstractCurrent Higgs data at the Large Hadron Collider is compatible with a SM signal at the 2σ level, but the central value of the signal strength in the diphoton channel is enhanced with respect to the SM expectation. If the enhancement resides in the diphoton partial decay width, the data could be accommodated in the Minimally Super-symmetric Standard Model (MSSM) with highly mixed light staus. We revisit the issue of vacuum instability induced by large mixing in the stau sector, including effects of a radiatively-corrected tau Yukawa coupling. Further, we emphasize the importance of taking into account the tan β dependence in the stability bound. While the metastability of the Universe constrains the possible enhancement in the Higgs to diphoton decay width in the light stau scenario, an increase of the order of 50% can be achieved in the region of large tan β. Larger enhancements may be obtained, but would require values of tan β associated with non-perturbative values of the tau Yukawa coupling at scales below the GUT scale, thereby implying the presence of new physics beyond the MSSM.

title: Determining the structure of supersymmetry breaking with renormalization group invariants
abstract: If collider experiments demonstrate that the minimal supersymmetric standard model (MSSM) is a good description of nature at the weak scale, the experimental priority will be the precise determination of superpartner masses. These masses are governed by the weak scale values of the soft supersymmetry-breaking (SUSY-breaking) parameters, which are in turn highly dependent on the SUSY-breaking scheme present at high scales. It is therefore of great interest to find patterns in the soft parameters that can distinguish different high-scale SUSY-breaking structures, identify the scale at which the breaking is communicated to the visible sector, and determine the soft breaking parameters at that scale. In this work, we demonstrate that 1-loop renormalization group invariant quantities present in the MSSM may be used to answer each of these questions. We apply our method first to generic flavor-blind models of SUSY breaking, and then we examine in detail the subset of these models described by general gauge mediation and the constrained MSSM with nonuniversal Higgs masses. As renormalization group invariance generally does not hold beyond leading-log order, we investigate the magnitude and direction of the 2-loop corrections. We find that with superpartners at the TeV scale, these 2-loop effects are either negligible, ormore » they are of the order of optimistic experimental uncertainties and have definite signs, which allows them to be easily accounted for in the overall uncertainty.« less

title: Collider phenomenology of gauge-Higgs unification scenarios in warped extra dimensions
abstract: We compute the couplings of the zero modes and first excited states of gluons, W's, Z gauge bosons, as well as the Higgs, to the zero modes and first excited states of the third generation quarks, in a Randall-Sundrum Gauge-Higgs unification scenario based on a bulk SO(5)xU(1){sub X} gauge symmetry, with gauge and fermion fields propagating in the bulk. Using the parameter space consistent with electroweak precision tests and radiative electroweak symmetry breaking, we study numerically the dependence of these couplings on the parameters of our model. Furthermore, after emphasizing the presence of light excited states of the top quark, which couple strongly to the Kaluza-Klein gauge bosons, the associated collider phenomenology is analyzed. In particular, we concentrate on the possible detection of the first excited state of the top, t{sup 1}, which tends to have a higher mass than the ones accessible via regular QCD production processes. We stress that the detection of these particles is still possible due to an increase in the pair production of t{sup 1} induced by the first excited state of the gluon, G{sup 1}.

title: Gravitons and dark matter in universal extra dimensions
abstract: Models of universal extra dimensions (UED) at the TeV scale lead to the presence of Kaluza Klein (KK) excitations of the ordinary fermions and bosons of the standard model that may be observed at hadron and lepton colliders. A conserved discrete symmetry, KK-parity, ensures the stability of the lightest KK particle (LKP), which, if neutral, becomes a good dark matter particle. It has been recently shown that for a certain range of masses of the LKP a relic density consistent with the experimentally observed one may be obtained. These works, however, ignore the impact of KK graviton production at early times. Whether the G{sup 1} is the LKP or not, the G{sup n} tower thus produced can decay to the LKP, and depending on the reheating temperature, may lead to a modification of the relic density. In this article, we show that this effect may lead to a relevant modification of the range of KK masses consistent with the observed relic density. Additionally, if evidence for UED is observed experimentally, we find a stringent upper limit on the reheating temperature depending on the mass of the LKP observed.

title: RADIO SHOWERS AT MT. CHACALTAYA.

title: Longitudinal and transverse spin asymmetries for inclusive jet production at mid-rapidity in polarized p+p collisions at sqrt{s}=200 GeV
abstract: We report STAR measurements of the longitudinal double-spin asymmetry A_LL, the transverse single-spin asymmetry A_N, and the transverse double-spin asymmetries A_Sigma and A_TT for inclusive jet production at mid-rapidity in polarized p+p collisions at a center-of-mass energy of sqrt{s} = 200 GeV. The data represent integrated luminosities of 7.6 /pb with longitudinal polarization and 1.8 /pb with transverse polarization, with 50-55% beam polarization, and were recorded in 2005 and 2006. No evidence is found for the existence of statistically significant jet A_N, A_Sigma, or A_TT at mid-rapidity. Recent model calculations indicate the A_N results may provide new limits on the gluon Sivers distribution in the proton. The asymmetry A_LL significantly improves the knowledge of gluon polarization in the nucleon.

title: Femtoscopy of identified particles at STAR
abstract: We present new measurements of Λ – Λ correlations, which are closely related to the H -dibaryon: a six quark state predicted by Jaffe [R. Jaffe,  (1977) 195], in Au + Au collisions at s N N = 200 GeV from the STAR experiment. Fits to different potential models are discussed and the extracted scattering length and effective range are also presented. We also present a spherical harmonic decomposition of the pion-kaon correlation function for 0–5% centrality in Au + Au collisions at s N N = 200 GeV . Finally, we discuss results from azimuthal HBT for collision energies in the range 7.7–200 GeV.

title: Energy and system-size dependence of two- and four-particle $v_2$ measurements in heavy-ion collisions at RHIC and their implications on flow fluctuations and nonflow
abstract: We present STAR measurements of azimuthal anisotropy by means of the two- and four-particle cumulants $v_2$ ($v_2\{2\}$ and $v_2\{4\}$) for Au+Au and Cu+Cu collisions at center of mass energies $\sqrt{s_{_{\mathrm{NN}}}} = 62.4$ and 200 GeV. The difference between $v_2\{2\}^2$ and $v_2\{4\}^2$ is related to $v_{2}$ fluctuations ($\sigma_{v_2}$) and nonflow $(\delta_{2})$. We present an upper limit to $\sigma_{v_2}/v_{2}$. Following the assumption that eccentricity fluctuations $\sigma_{\epsilon}$ dominate $v_2$ fluctuations $\frac{\sigma_{v_2}}{v_2} \approx \frac{\sigma_{\epsilon}}{\epsilon}$ we deduce the nonflow implied for several models of eccentricity fluctuations that would be required for consistency with $v_2\{2\}$ and $v_2\{4\}$. We also present results on the ratio of $v_2$ to eccentricity.

title: Measurement of longitudinal spin asymmetries for weak boson production in polarized proton-proton collisions at RHIC.
abstract: We report measurements of single- and double-spin asymmetries for W^{±} and Z/γ^{*} boson production in longitudinally polarized p+p collisions at sqrt[s]=510  GeV by the STAR experiment at RHIC. The asymmetries for W^{±} were measured as a function of the decay lepton pseudorapidity, which provides a theoretically clean probe of the proton's polarized quark distributions at the scale of the W mass. The results are compared to theoretical predictions, constrained by polarized deep inelastic scattering measurements, and show a preference for a sizable, positive up antiquark polarization in the range 0.05