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.
56430796
Measurements of $D^{0}$ and $D^{*}$ Production in $p$ + $p$ Collisions at $\sqrt{s}$ = 200 GeV
We report measurements of charmed-hadron ($D^{0}$, $D^{*}$) production cross sections at mid-rapidity in $p$ + $p$ collisions at a center-of-mass energy of 200 GeV by the STAR experiment. Charmed hadrons were reconstructed via the hadronic decays $D^{0}\rightarrow K^{-}\pi^{+}$, $D^{*+}\rightarrow D^{0}\pi^{+}\rightarrow K^{-}\pi^{+}\pi^{+}$ and their charge conjugates, covering the $p_T$ range of 0.6$-$2.0 GeV/$c$ and 2.0$-$6.0 GeV/$c$ for $D^{0}$ and $D^{*+}$, respectively. From this analysis, the charm-pair production cross section at mid-rapidity is $d\sigma/dy|_{y=0}^{c\bar{c}}$ = 170 $\pm$ 45 (stat.) $^{+38}_{-59}$ (sys.) $\mu$b. The extracted charm-pair cross section is compared to perturbative QCD calculations. The transverse momentum differential cross section is found to be consistent with the upper bound of a Fixed-Order Next-to-Leading Logarithm calculation.
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.
118375808
Determining the structure of supersymmetry breaking with renormalization group invariants
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
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}.
5210769
Braneworld graviton interactions in early universe phase transitions
This chapter discusses the Braneworld models that solve the hierarchy problem. The chapter focuses on Randall-Sundrum (RS) type models that embed one or two branes into a five dimensional AdS bulk. In RS 1, a static solution of the 5d Einstein equations is derived with two branes of opposite tension at the orbifold fixed points of the finite fifth dimension. Low-scale gravity leads to low reheating temperatures, and it is possible to obtain temperatures lower than the electroweak scale. This implies that the electroweak phase transition can take place before the completion of reheating. The chapter discusses how the gravitons couple in order to matter fields on the brane. The KK decomposition, graviton propagators and their coupling to matter and gauge fields are considered for toroidal extra dimensions and the analysis for the infinite AdS bulks have to be repeated.
5169671
Collision and Symmetry Breaking in the Transition to Strange Nonchaotic Attractors
Strange nonchaotic attractors (SNAs) can be created due to the collision of an invariant curve with itself. This novel "homoclinic" transition to SNAs occurs in quasiperiodically driven maps which derive from the discrete Schrodinger equation for a particle in a quasiperiodic potential. In the classical dynamics, there is a transition from torus attractors to SNAs, which, in the quantum system, is manifest as the localization transition. This equivalence provides new insight into a variety of properties of SNAs, including its fractal measure. Further, there is a symmetry breaking associated with the creation of SNAs which rigorously shows that the Lyapunov exponent is nonpositive. We show that these characteristics associated with the appearance of SNA are robust and occur in a large class of systems.
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.