5,494 research outputs found

    Recent results on beyond the standard model Higgs boson searches from CMS

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    Two extensions of the standard model, one that includes the seesaw mechanism of type II, and the minimal supersymmetric extention to the standard model, are studied using up to 1.6 fb^{-1} of data collected in proton-proton collisions at sqrt{s}=7 TeV with the CMS detector at the LHC.Comment: Presented at the 2011 Hadron Collider Physics symposium (HCP-2011), Paris, France, November 14-18 2011, 3 pages, 5 figure

    Prospects for Higgs and SM measurements at the HL-LHC

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    After a succesful startup of the LHC scientific program that has led to discovery of the Higgs boson it is time to make plans for the future. The high luminosity LHC (HLLHC) project is discussed, plans for possible Higgs and SM measurements are reviewed

    Nonlinear Breathing-like Localized Modes in C60 Nanocrystals

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    We study the dynamics of nanocrystals composed of C60 fullerene molecules. We demonstrate that such structures can support long-lived strongly localized nonlinear oscillatory modes, which resemble discrete breathers in simple lattices. We reveal that at room temperatures the lifetime of such nonlinear localized modes may exceed tens of picoseconds; this suggests that C60 nanoclusters should demonstrate anomalously slow thermal relaxation when the temperature gradient decays in accord to a power law, thus violating the Cattaneo-Vernotte law of thermal conductivity.Comment: 6 pages, 6 figure

    Non-stationary heat conduction in one-dimensional chains with conserved momentum

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    The Letter addresses the relationship between hyperbolic equations of heat conduction and microscopic models of dielectrics. Effects of the non-stationary heat conduction are investigated in two one-dimensional models with conserved momentum: Fermi-Pasta-Ulam (FPU) chain and chain of rotators (CR). These models belong to different universality classes with respect to stationary heat conduction. Direct numeric simulations reveal in both models a crossover from oscillatory decay of short-wave perturbations of the temperature field to smooth diffusive decay of the long-wave perturbations. Such behavior is inconsistent with parabolic Fourier equation of the heat conduction. The crossover wavelength decreases with increase of average temperature in both models. For the FPU model the lowest order hyperbolic Cattaneo-Vernotte equation for the non-stationary heat conduction is not applicable, since no unique relaxation time can be determined.Comment: 4 pages, 5 figure

    Vibrational Tamm states at the edges of graphene nanoribbons

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    We study vibrational states localized at the edges of graphene nanoribbons. Such surface oscillations can be considered as a phonon analog of Tamm states well known in the electronic theory. We consider both armchair and zigzag graphene stripes and demonstrate that surface modes correspond to phonons localized at the edges of the graphene nanoribbon, and they can be classified as in-plane and out-of-plane modes. In addition, in armchair nanoribbons anharmonic edge modes can experience longitudinal localization in the form of self-localized nonlinear modes, or surface breather solitons.Comment: 10 pages, 10 figure

    Precision measurements of electroweak parameters at the LHC

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    A set of selected precise measurements of the SM parameters from the LHC experiments is discussed. Results on W-mass measurement and forwardbackward asymmetry in production of the Drell-Yan events in both dielectron and dimuon decay channels are presented together with results on the effective mixing angle measurements. Electroweak production of the vector bosons in association with two jets is discussed

    Discrete breathers assist energy transfer to ac driven nonlinear chains

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    One-dimensional chain of pointwise particles harmonically coupled with nearest neighbors and placed in six-order polynomial on-site potentials is considered. Power of the energy source in the form of single ac driven particles is calculated numerically for different amplitudes AA and frequencies ω\omega within the linear phonon band. The results for the on-site potentials with hard and soft nonlinearity types are compared. For the hard-type nonlinearity, it is shown that when the driving frequency is close to (far from) the {\em upper} edge of the phonon band, the power of the energy source normalized to A2A^2 increases (decreases) with increasing AA. In contrast, for the soft-type nonlinearity, the normalized power of the energy source increases (decreases) with increasing AA when the driving frequency is close to (far from) the {\em lower} edge of the phonon band. Our further demonstrations indicate that, in the case of hard (soft) anharmonicity, the chain can support movable discrete breathers (DBs) with frequencies above (below) the phonon band. It is the energy source quasi-periodically emitting moving DBs in the regime with driving frequency close to the DBs frequency, that induces the increase of the power. Therefore, our results here support the mechanism that the moving DBs can assist energy transfer from the ac driven particle to the chain.Comment: 11 pages, 13 figure
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