10,274 research outputs found

    Analytic calculation of radio emission from parametrized extensive air showers:A tool to extract shower parameters

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    The radio intensity and polarization footprint of a cosmic-ray induced extensive air shower is determined by the time-dependent structure of the current distribution residing in the plasma cloud at the shower front. In turn, the time dependence of the integrated charge-current distribution in the plasma cloud, the longitudinal shower structure, is determined by interesting physics which one would like to extract, such as the location and multiplicity of the primary cosmic-ray collision or the values of electric fields in the atmosphere during thunderstorms. To extract the structure of a shower from its footprint requires solving a complicated inverse problem. For this purposewe have developed a code that semianalytically calculates the radio footprint of an extensive air shower given an arbitrary longitudinal structure. This code can be used in an optimization procedure to extract the optimal longitudinal shower structure given a radio footprint. On the basis of air-shower universality we propose a simple parametrization of the structure of the plasma cloud. This parametrization is based on the results of Monte Carlo shower simulations. Deriving the parametrization also teaches which aspects of the plasma cloud are important for understanding the features seen in the radio-emission footprint. The calculated radio footprints are compared with microscopic CoREAS simulations

    Supersymmetric Dark Matter after LHC Run 1

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    Different mechanisms operate in various regions of the MSSM parameter space to bring the relic density of the lightest neutralino, neutralino_1, assumed here to be the LSP and thus the Dark Matter (DM) particle, into the range allowed by astrophysics and cosmology. These mechanisms include coannihilation with some nearly-degenerate next-to-lightest supersymmetric particle (NLSP) such as the lighter stau (stau_1), stop (stop_1) or chargino (chargino_1), resonant annihilation via direct-channel heavy Higgs bosons H/A, the light Higgs boson h or the Z boson, and enhanced annihilation via a larger Higgsino component of the LSP in the focus-point region. These mechanisms typically select lower-dimensional subspaces in MSSM scenarios such as the CMSSM, NUHM1, NUHM2 and pMSSM10. We analyze how future LHC and direct DM searches can complement each other in the exploration of the different DM mechanisms within these scenarios. We find that the stau_1 coannihilation regions of the CMSSM, NUHM1, NUHM2 can largely be explored at the LHC via searches for missing E_T events and long-lived charged particles, whereas their H/A funnel, focus-point and chargino_1 coannihilation regions can largely be explored by the LZ and Darwin DM direct detection experiments. We find that the dominant DM mechanism in our pMSSM10 analysis is chargino_1 coannihilation: {parts of its parameter space can be explored by the LHC, and a larger portion by future direct DM searches.Comment: 21 pages, 8 figure

    The pMSSM10 after LHC Run 1

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    We present a frequentist analysis of the parameter space of the pMSSM10, in which the following 10 soft SUSY-breaking parameters are specified independently at the mean scalar top mass scale Msusy = Sqrt[M_stop1 M_stop2]: the gaugino masses M_{1,2,3}, the 1st-and 2nd-generation squark masses M_squ1 = M_squ2, the third-generation squark mass M_squ3, a common slepton mass M_slep and a common trilinear mixing parameter A, the Higgs mixing parameter mu, the pseudoscalar Higgs mass M_A and tan beta. We use the MultiNest sampling algorithm with 1.2 x 10^9 points to sample the pMSSM10 parameter space. A dedicated study shows that the sensitivities to strongly-interacting SUSY masses of ATLAS and CMS searches for jets, leptons + MET signals depend only weakly on many of the other pMSSM10 parameters. With the aid of the Atom and Scorpion codes, we also implement the LHC searches for EW-interacting sparticles and light stops, so as to confront the pMSSM10 parameter space with all relevant SUSY searches. In addition, our analysis includes Higgs mass and rate measurements using the HiggsSignals code, SUSY Higgs exclusion bounds, the measurements B-physics observables, EW precision observables, the CDM density and searches for spin-independent DM scattering. We show that the pMSSM10 is able to provide a SUSY interpretation of (g-2)_mu, unlike the CMSSM, NUHM1 and NUHM2. As a result, we find (omitting Higgs rates) that the minimum chi^2/dof = 20.5/18 in the pMSSM10, corresponding to a chi^2 probability of 30.8 %, to be compared with chi^2/dof = 32.8/24 (31.1/23) (30.3/22) in the CMSSM (NUHM1) (NUHM2). We display 1-dimensional likelihood functions for SUSY masses, and show that they may be significantly lighter in the pMSSM10 than in the CMSSM, NUHM1 and NUHM2. We discuss the discovery potential of future LHC runs, e+e- colliders and direct detection experiments.Comment: 47 pages, 29 figure

    The NUHM2 after LHC Run 1

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    We make a frequentist analysis of the parameter space of the NUHM2, in which the soft supersymmetry (SUSY)-breaking contributions to the masses of the two Higgs multiplets, mHu,d2m^2_{H_{u,d}}, vary independently from the universal soft SUSY-breaking contributions m02m^2_0 to the masses of squarks and sleptons. Our analysis uses the MultiNest sampling algorithm with over 4×1084 \times 10^8 points to sample the NUHM2 parameter space. It includes the ATLAS and CMS Higgs mass measurements as well as their searches for supersymmetric jets + MET signals using the full LHC Run~1 data, the measurements of Bsμ+μB_s \to \mu^+ \mu^- by LHCb and CMS together with other B-physics observables, electroweak precision observables and the XENON100 and LUX searches for spin-independent dark matter scattering. We find that the preferred regions of the NUHM2 parameter space have negative SUSY-breaking scalar masses squared for squarks and sleptons, m02<0m_0^2 < 0, as well as mHu2<mHd2<0m^2_{H_u} < m^2_{H_d} < 0. The tension present in the CMSSM and NUHM1 between the supersymmetric interpretation of gμ2g_\mu - 2 and the absence to date of SUSY at the LHC is not significantly alleviated in the NUHM2. We find that the minimum χ2=32.5\chi^2 = 32.5 with 21 degrees of freedom (dof) in the NUHM2, to be compared with χ2/dof=35.0/23\chi^2/{\rm dof} = 35.0/23 in the CMSSM, and χ2/dof=32.7/22\chi^2/{\rm dof} = 32.7/22 in the NUHM1. We find that the one-dimensional likelihood functions for sparticle masses and other observables are similar to those found previously in the CMSSM and NUHM1.Comment: 20 pages latex, 13 figure

    Properties of 8^{8}Be and 12^{12}C deduced from the folding--potential model

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    The α\alpha--α\alpha differential cross sections are analyzed in the optical model using a double--folded potential. With the knowledge of this potential bound and resonance--state properties of α\alpha--cluster states in 8^{8}Be and 12^{12}C as well as astrophysical S--factors of 4^{4}He(α\alpha,γ\gamma)8^{8}Be and 8^{8}Be(α\alpha,γ\gamma)12^{12}C are calculated. Γγ\Gamma_{\gamma}--widths and B(E2)--values are deduced.Comment: 2 pages LaTeX, 2 figures can be obtained from the author

    The Cone Phase of Liquid Crystals: Triangular Lattice of Double-Tilt Cylinders

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    We predict the existence of a new defect-lattice phase near the nematic - smectic-C (NC) transition. This tilt- analogue of the blue phase is a lattice of double-tilt cylinders. We discuss the structure and stability of the cone phase. We suggest that many `nematics' exhibiting short range layering and tilt order may in fact be in the molten cone phase, which is a line liquid.Comment: 4 Pages, 3 Figure

    Quantifying Social Asymmetric Structures

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    Many social phenomena involve a set of dyadic relations among agents whose actions may be dependent. Although individualistic approaches have frequently been applied to analyze social processes, these are not generally concerned with dyadic relations nor do they deal with dependency. This paper describes a mathematical procedure for analyzing dyadic interactions in a social system. The proposed method mainly consists of decomposing asymmetric data into their symmetrical and skew-symmetrical parts. A quantification of skew-symmetry for a social system can be obtained by dividing the norm of the skew-symmetrical matrix by the norm of the asymmetric matrix. This calculation makes available to researchers a quantity related to the amount of dyadic reciprocity. Regarding agents, the procedure enables researchers to identify those whose behavior is asymmetric with respect to all agents. It is also possible to derive symmetric measurements among agents and to use multivariate statistical techniques

    Optical Spectroscopy of Galactic Cirrus Clouds: Extended Red Emission in the Diffuse Interstellar Medium

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    We present initial results from the first optical spectroscopic survey of high latitude Galactic cirrus clouds. The observed shape of the cirrus spectrum does not agree with that of scattered ambient Galactic starlight. This mismatch can be explained by the presence of Extended Red Emission (ERE) in the diffuse interstellar medium, as found in many other astronomical objects, probably caused by photoluminescence of hydrocarbons. The integrated ERE intensity, I_ERE \approx 1.2 x 10^{-5} erg s^{-1} cm^{-2} sr^{-1}, is roughly a third of the scattered light intensity, consistent with recent color measurements of diffuse Galactic light. The peak of the cirrus ERE (lambda_{0} \sim 6000 AA) is shifted towards short (bluer) wavelengths compared to the ERE in sources excited by intense ultraviolet radiation, such as HII regions (lambda_{0} sim 8000 AA); such a trend is seen in laboratory experiments on hydrogenated amorphous carbon films.Comment: 7 pages, 2 figures. Accepted for publication in ApJ Letter
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