119232438
Study of hyperon-hyperon correlations and search for $H$-dibaryon using STAR detector at RHIC
High yield of strange particle production per central collision in nucleus-nucleus collisions at RHIC and high statistics data set from STAR experiment allow us to measure \Lambda\Lambda correlations. The \Lambda\Lambda correlation measurement is also closely related to a possible six-quark state H-dibaryon, which is yet to be observed experimentally. The first measurement of \Lambda\Lambda correlations in Au+Au collisions for \sqrt{s_{NN}}= 39, 62.4 and 200 GeV and search for H-dibaryon with its weak decay \Lambda p\pi in Au+Au collisions for \sqrt{s_{NN}}= 200 GeV using the STAR experiment at RHIC are presented here.
4490264
Energy dependence of moments of net-proton multiplicity distributions at RHIC.
We report the beam energy (sqrt[sNN]=7.7-200  GeV) and collision centrality dependence of the mean (M), standard deviation (σ), skewness (S), and kurtosis (κ) of the net-proton multiplicity distributions in Au+Au collisions. The measurements are carried out by the STAR experiment at midrapidity (|y|<0.5) and within the transverse momentum range 0.4<pT<0.8  GeV/c in the first phase of the Beam Energy Scan program at the Relativistic Heavy Ion Collider. These measurements are important for understanding the quantum chromodynamic phase diagram. The products of the moments, Sσ and κσ2, are sensitive to the correlation length of the hot and dense medium created in the collisions and are related to the ratios of baryon number susceptibilities of corresponding orders. The products of moments are found to have values significantly below the Skellam expectation and close to expectations based on independent proton and antiproton production. The measurements are compared to a transport model calculation to understand the effect of acceptance and baryon number conservation and also to a hadron resonance gas model.
123142973
Elliptic flow of non-photonic electrons in Au+Au collisions at $\sqrt{s_{\rm NN}} = $ 200, 62.4 and 39 GeV
We present the measurements of elliptic flow ($v_2$) of non-photonic electrons (NPE) by the STAR experiment using 2- and 4-particle correlations, $v_2${2} and $v_2${4}, and the event plane method in Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV, and $v_2${2} at 62.4 and 39 GeV. $v_2${2} and $v_2${4} are non-zero at low and intermediate transverse momentum ($p_T$) at 200 GeV, and $v_2${2} is consistent with zero at low $p_T$ at other energies. For Au+Au collisions at $p_T<1$ GeV/c, there is a statistically significant difference between $v_2${2} at 200 GeV and $v_2${2} at the two lower beam energies.
123105671
Radio pulses and the detection of large air showers
118405509
ABC Effect in Basic Double-Pionic Fusion --- Observation of a new resonance?
P. Adlarson, C. Adolph, W. Augustyniak, V. Baru, 5 M. Bashkanov, F.S. Bergmann, M. Berłowski, H. Bhatt, K.–T. Brinkmann, M. Büscher, 11 H. Calén, H. Clement, D. Coderre, 11, 12 E. Czerwiński, ∗ E. Doroshkevich, C. Ekström, R. Engels, 11 W. Erven, 11 W. Eyrich, P. Fedorets, 5 K. Föhl, K. Fransson, F. Goldenbaum, 11 P. Goslawski, K. Grigoryev, 11, 17 V. Grishina, C.–O. Gullström, J. Hampe, 11, 18 C. Hanhart, 11, 19 L. Heijkenskjöld, V. Hejny, 11 F. Hinterberger, M. Hodana, 11, 13 B. Höistad, M. Jacewicz, M. Janusz, A. Jany, B.R. Jany, L. Jarczyk, J. Jaus, T. Johansson, B. Kamys, G. Kemmerling, 11 O. Khakimova, A. Khoukaz, S. Kistryn, J. Klaja, 11, 13 H. Kleines, 11 B. Kłos, F. Kren, W. Krzemień, P. Kulessa, S. Kullander, A. Kupść, K. Lalwani, B. Lorentz, 11 A. Magiera, R. Maier, 11 P. Marciniewski, B. Mariański, M. Mikirtychiants, 11, 17 P. Moskal, H.–P. Morsch, B.K. Nandi, H. Ohm, 11 A. Passfeld, C. Pauly, 11, † E. Perez del Rio, Y. Petukhov, N. Piskunov, P. Pluciński, P. Podkopał, A. Povtoreyko, D. Prasuhn, 11 A. Pricking, 10 K. Pysz, T. Rausmann, C.F. Redmer, J. Ritman, 11, 12 A. Roy, R.J.M.Y. Ruber, Z. Rudy, S. Schadmand, 11 A. Schmidt, W. Schroeder, T. Sefzick, 11 V. Serdyuk, 11, 24 N. Shah, M. Siemaszko, R. Siudak, T. Skorodko, M. Skurzok, J. Smyrski, V. Sopov, R. Stassen, 11 J. Stepaniak, G. Sterzenbach, 11 H. Stockhorst, 11 H. Ströher, 11 A. Szczurek, A. Täschner, T. Tolba, 11 A. Trzciński, R. Varma, P. Vlasov, G.J. Wagner, W. Węglorz, A. Winnemöller, A. Wirzba, 11, 19 M. Wolke, A. Wrońska, P. Wüstner, 11 P. Wurm, 11 L. Yurev, 11, 24 J. Zabierowski, M.J. Zieliński, W. Zipper, J. Złomańczuk, and P. Żuprański
27276714
Precision Measurement of the Longitudinal Double-Spin Asymmetry for Inclusive Jet Production in Polarized Proton Collisions at sqrt[s]=200  GeV.
We report a new measurement of the midrapidity inclusive jet longitudinal double-spin asymmetry, A_{LL}, in polarized pp collisions at center-of-mass energy sqrt[s]=200  GeV. The STAR data place stringent constraints on polarized parton distribution functions extracted at next-to-leading order from global analyses of inclusive deep-inelastic scattering (DIS), semi-inclusive DIS, and RHIC pp data. The measured asymmetries provide evidence at the 3σ level for positive gluon polarization in the Bjorken-x region x>0.05.
118570168
SUSY-Breaking Parameters from RG Invariants at the LHC
We study Renormalization Group invariant (RGI) quantities in the Minimal Supersymmetric Standard Model and show that they are a powerful and simple instrument for testing high scale models of supersymmetry (SUSY)-breaking. For illustration, we analyze the frameworks of minimal and general gauge mediated (MGM and GGM) SUSY-breaking, with additional arbitrary soft Higgs mass parameters at the messenger scale. We show that if a gaugino and two first generation sfermion soft masses are determined at the LHC, the RGIs lead to MGM sum rules that yield accurate predictions for the other gaugino and first generation soft masses. RGIs can also be used to reconstruct the fundamental MGM parameters (including the messenger scale), calculate the hypercharge D-term, and find relationships among the third generation and Higgs soft masses. We then study the extent to which measurements of the full first generation spectrum at the LHC may distinguish different SUSY-breaking scenarios. In the case of MGM, although most deviations violate the sum rules by more than estimated experimental errors, we find a 1-parameter family of GGM models that satisfy the constraints and produce the same first generation spectrum. The GGM-MGM degeneracy is lifted by differences in the third generation masses and the messenger scales. ∗http://theory.fnal.gov ar X iv :1 01 1. 49 58 v2 [ he pph ] 1 0 M ar 2 01 1
119302337
Gauge-Higgs unification, neutrino masses, and dark matter in warped extra dimensions
Gauge-Higgs unification in warped extra dimensions provides an attractive solution to the hierarchy problem. The extension of the standard model gauge symmetry to SO(5)xU(1){sub X} allows the incorporation of the custodial symmetry SU(2){sub R} plus a Higgs boson doublet with the right quantum numbers under the gauge group. In the minimal model, the Higgs mass is in the range 110-150 GeV, while a light Kaluza-Klein excitation of the top quark appears in the spectrum, providing agreement with precision electroweak measurements and a possible test of the model at a high luminosity LHC. The extension of the model to the lepton sector has several interesting features. We discuss the conditions necessary to obtain realistic charged lepton and neutrino masses. After the addition of an exchange symmetry in the bulk, we show that the odd neutrino Kaluza-Klein modes provide a realistic dark-matter candidate, with a mass of the order of 1 TeV, which will be probed by direct dark-matter detection experiments in the near future.
118481994
Vacuum stability and Higgs diphoton decays in the MSSM
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.
119280954
Indirect probes of the MSSM after the Higgs discovery
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.
15780949
Collider phenomenology of gauge-Higgs unification scenarios in warped extra dimensions
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}.