Advances in High Energy Physics
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Open Access journal
ISSN (Print) 1687-7357 - ISSN (Online) 1687-7365
Published by Hindawi Publishing Corporation [356 journals] [SJR: 1.297] [H-I: 7]
- CνB Damping of Primordial Gravitational Waves and the Fine-Tuning of
the CγB Temperature Anisotropy
Abstract: Damping of primordial gravitational waves due to the anisotropic stress contribution owing to the cosmological neutrino background (CνB) is investigated in the context of a radiation-to-matter dominated universe. Besides its inherent effects on the gravitational wave propagation, the inclusion of the CνB anisotropic stress into the dynamical equations also affects the tensor mode contribution to the anisotropy of the cosmological microwave background (CγB) temperature. The mutual effects on the gravitational waves and on the CγB are obtained through a unified prescription for a radiation-to-matter dominated scenario. The results are confronted with some preliminary results for the radiation dominated scenario. Both scenarios are supported by a simplified analytical framework, in terms of a scale independent dynamical variable, kη, that relates cosmological scales, k, and the conformal time, η. The background relativistic (hot dark) matter essentially works as an effective dispersive medium for the gravitational waves such that the damping effect is intensified for the universe evolving to the matter dominated era. Changes on the temperature variance owing to the inclusion of neutrino collision terms into the dynamical equations result in spectral features that ratify that the multipole expansion coefficients ’s die out for .
PubDate: Mon, 01 Sep 2014 05:51:03 +000
- Interacting Quintessence Dark Energy Models in Lyra Manifold
Abstract: We consider two-component dark energy models in Lyra manifold. The first component is assumed to be a quintessence field while the second component may be a viscous polytropic gas, a viscous Van der Waals gas, or a viscous modified Chaplygin gas. We also consider the possibility of interaction between components. By using the numerical analysis, we study some cosmological parameters of the models and compare them with observational data.
PubDate: Mon, 01 Sep 2014 00:00:00 +000
- Quantum Haplodynamics, Dark Matter, and Dark Energy
Abstract: In quantum haplodynamics (QHD) the weak bosons, quarks, and leptons are bound states of fundamental constituents, denoted as haplons. The confinement scale of the associated gauge group is of the order of TeV. One scalar state has zero haplon number and is the resonance observed at the LHC. In addition, there exist new bound states of haplons with no counterpart in the SM, having a mass of the order of 0.5 TeV up to a few TeV. In particular, a neutral scalar state with haplon number 4 is stable and can provide the dark matter in the universe. The QHD, QCD, and QED couplings can unify at the Planck scale. If this scale changes slowly with cosmic time, all of the fundamental couplings, the masses of the nucleons and of the DM particles, including the cosmological term (or vacuum energy density), will evolve with time. This could explain the dark energy of the universe.
PubDate: Sun, 31 Aug 2014 09:00:41 +000
- On Descriptions of Particle Transverse Momentum Spectra in High Energy
Abstract: The transverse momentum spectra obtained in the frame of an isotropic emission source are compared in terms of Tsallis, Boltzmann, Fermi-Dirac, and Bose-Einstein distributions and the Tsallis forms of the latter three standard distributions. It is obtained that, at a given set of parameters, the standard distributions show a narrower shape than their Tsallis forms which result in wide and/or multicomponent spectra with the Tsallis distribution in between. A comparison among the temperatures obtained from the distributions is made with a possible relation to the Boltzmann temperature. An example of the angular distributions of projectile fragments in nuclear collisions is given.
PubDate: Thu, 28 Aug 2014 11:32:18 +000
- Testing a Dilaton Gravity Model Using Nucleosynthesis
Abstract: Big bang nucleosynthesis (BBN) offers one of the most strict evidences for the -CDM cosmology at present, as well as the cosmic microwave background (CMB) radiation. In this work, our main aim is to present the outcomes of our calculations related to primordial abundances of light elements, in the context of higher dimensional steady-state universe model in the dilaton gravity. Our results show that abundances of light elements (primordial D, 3He, 4He, T, and 7Li) are significantly different for some cases, and a comparison is given between a particular dilaton gravity model and -CDM in the light of the astrophysical observations.
PubDate: Wed, 27 Aug 2014 08:38:29 +000
- A Systematic Study of Magnetic Field in Relativistic Heavy-Ion Collisions
in the RHIC and LHC Energy Regions
Abstract: The features of magnetic field in relativistic heavy-ion collisions are systematically studied by using a modified magnetic field model in this paper. The features of magnetic field distributions in the central point are studied in the RHIC and LHC energy regions. We also predict the feature of magnetic fields at LHC , 2760, and 7000 GeV based on the detailed study at RHIC , 130, and 200 GeV. The dependencies of the features of magnetic fields on the collision energies, centralities, and collision time are systematically investigated, respectively.
PubDate: Tue, 26 Aug 2014 06:27:04 +000
- Residual Symmetries Applied to Neutrino Oscillations at NOA and T2K
Abstract: The results previously obtained from the model-independent application of a generalized hidden horizontal symmetry to the neutrino mass matrix are updated using the latest global fits for the neutrino oscillation parameters. The resulting prediction for the Dirac phase is in agreement with recent results from T2K. The distribution for the Jarlskog invariant has become sharper and appears to be approaching a particular region. The approximate effects of matter on long-baseline neutrino experiments are explored, and it is shown how the weak interactions between the neutrinos and the particles that make up the Earth can help to determine the mass hierarchy. A similar strategy is employed to show how NOA and T2K could determine the octant of . Finally, the exact effects of matter are obtained numerically in order to make comparisons with the form of the approximate solutions. From this analysis there emerge some interesting features of the effective mass eigenvalues.
PubDate: Sun, 24 Aug 2014 12:18:54 +000
- Gravitational Resonance Spectroscopy with an Oscillating Magnetic Field
Gradient in the GRANIT Flow through Arrangement
Abstract: Gravitational resonance spectroscopy consists in measuring the energy spectrum of bouncing ultracold neutrons above a mirror by inducing resonant transitions between different discrete quantum levels. We discuss how to induce the resonances with a flow through arrangement in the GRANIT spectrometer, excited by an oscillating magnetic field gradient. The spectroscopy could be realized in two distinct modes (so called DC and AC) using the same device to produce the magnetic excitation. We present calculations demonstrating the feasibility of the newly proposed AC mode.
PubDate: Sun, 24 Aug 2014 09:40:55 +000
- Magnetized Anisotropic Dark Energy Models in Barber’s Second
Abstract: The present paper deals with Bianchi type IX cosmological model with magnetized anisotropic dark energy by using Barber’s self-creation theory. The energy momentum tensor consists of anisotropic fluid with EoS parameter and a uniform magnetic field of energy density . In order to obtain the exact solution we have assumed that dark energy components and the components of magnetic field interact minimally and obey the law of conservation of energy momentum tensors. We have also used the special law of variation for the mean generalized Hubble parameter and power law relation between scalar field and scale factor. Some physical and kinematical properties of the models have been discussed.
PubDate: Sun, 24 Aug 2014 09:37:03 +000
- Tests of Lorentz Symmetry in Single Beta Decay
Abstract: Low-energy experiments studying single beta decay can serve as sensitive probes of Lorentz invariance that can complement interferometric searches for deviations from this spacetime symmetry. Experimental signatures of a dimension-three operator for Lorentz violation which are unobservable in neutrino oscillations are described for the decay of polarized and unpolarized neutrons as well as for measurements of the spectral endpoint in beta decay.
PubDate: Sun, 24 Aug 2014 09:11:25 +000
- Study of Confinement/Deconfinement Transition in AdS/QCD with Generalized
Abstract: We study analytical solutions of charged black holes and thermally charged AdS with generalized warped factors in Einstein-Maxwell-Dilaton system. We calculate Euclidean action for charged AdS and thermally charged AdS. The actions in both backgrounds are regularized by the method of background subtraction. The study of phase transition between charged black hole and thermally charged AdS gives an insight into the confinement/deconfinement transition. The plots of grand potential versus temperature and chemical potential versus transition temperature are obtained.
PubDate: Thu, 21 Aug 2014 11:14:14 +000
- Lorentz Violation of the Photon Sector in Field Theory Models
Abstract: We compare the Lorentz violation terms of the pure photon sector between two field theory models, namely, the minimal standard model extension (SME) and the standard model supplement (SMS). From the requirement of the identity of the intersection for the two models, we find that the free photon sector of the SMS can be a subset of the photon sector of the minimal SME. We not only obtain some relations between the SME parameters but also get some constraints on the SMS parameters from the SME parameters. The CPT-odd coefficients of the SME are predicted to be zero. There are 15 degrees of freedom in the Lorentz violation matrix of free photons of the SMS related with the same number of degrees of freedom in the tensor coefficients , which are independent from each other in the minimal SME but are interrelated in the intersection of the SMS and the minimal SME. With the related degrees of freedom, we obtain the conservative constraints on the elements of the photon Lorentz violation matrix. The detailed structure of the photon Lorentz violation matrix suggests some applications to the Lorentz violation experiments for photons.
PubDate: Thu, 21 Aug 2014 06:30:58 +000
- Slowly Rotating Black Holes with Nonlinear Electrodynamics
Abstract: We study charged slowly rotating black hole with a nonlinear electrodynamics (NED) in the presence of cosmological constant. Starting from the static solutions of Einstein-NED gravity as seed solutions, we use the angular momentum as the perturbative parameter to obtain slowly rotating black holes. We perform the perturbations up to the linear order for black holes in 4 dimensions. These solutions are asymptotically AdS and their horizon has spherical topology. We calculate the physical properties of these black holes and study their dependence on the rotation parameter as well as the nonlinearity parameter β. In the limit , the solution describes slowly rotating AdS type black holes.
PubDate: Wed, 20 Aug 2014 00:00:00 +000
- Initiating the Effective Unification of Black Hole Horizon Area and
Entropy Quantization with Quasi-Normal Modes
Abstract: Black hole (BH) area quantization may be the key to unlocking a unifying theory of quantum gravity (QG). Surmounting evidence in the field of BH research continues to support a horizon (surface) area with a discrete and uniformly spaced spectrum, but there is still no general agreement on the level spacing. In the specialized and important BH case study, our objective is to report and examine the pertinent groundbreaking work of the strictly thermal and nonstrictly thermal spectrum level spacing of the BH horizon area quantization with included entropy calculations, which aims to tackle this gigantic problem. In particular, such work exemplifies a series of imperative corrections that eventually permits a BH’s horizon area spectrum to be generalized from strictly thermal to nonstrictly thermal with entropy results, thereby capturing multiple preceding developments by launching an effective unification between them. Moreover, the results are significant because quasi-normal modes (QNM) and “effective states” characterize the transitions between the established levels of the nonstrictly thermal spectrum.
PubDate: Tue, 19 Aug 2014 06:33:37 +000
- The Low-Scale Approach to Neutrino Masses
Abstract: In this short review we revisit the broad landscape of low-scale models of neutrino mass generation, with view on their phenomenological potential. This includes signatures associated to direct neutrino mass messenger production at the LHC, as well as messenger-induced lepton flavor violation processes. We also briefly comment on the presence of WIMP cold dark matter candidates.
PubDate: Thu, 14 Aug 2014 13:46:34 +000
- Dihadron Azimuthal Correlations in 200 GeV Au-Au and
2.76 TeV Pb-Pb Collisions
Abstract: In a multisource thermal model, we detailedly show dihadron azimuthal correlations for 20–40% and 50–80% in Au-Au collisions at GeV and over a centrality range from 10–15% to 70–80% in Pb-Pb collisions at TeV. The model can approximately describe the azimuthal correlations of particles produced in the collisions. The amplitude of the corresponding source is magnified, and the source translates along the direction. The factor , in most cases, increases with the increase of the centrality in Pb-Pb collisions at TeV.
PubDate: Wed, 13 Aug 2014 12:08:31 +000
- Analytical Solution of the Schrödinger Equation with Spatially
Varying Effective Mass for Generalised Hylleraas Potential
Abstract: We have obtained exact solution of the effective mass Schrödinger equation for the generalised Hylleraas potential. The exact bound state energy eigenvalues and corresponding eigenfunctions are presented. The bound state eigenfunctions are obtained in terms of the hypergeometric functions. Results are also given for the special case of potential parameter.
PubDate: Mon, 11 Aug 2014 00:00:00 +000
- Transport Coefficients for Holographic Hydrodynamics at Finite Energy
Abstract: We investigate the relations between black hole thermodynamics and holographic transport coefficients in this paper. The formulae for DC conductivity and diffusion coefficient are verified for electrically single-charged black holes. We examine the correctness of the proposed expressions by taking charged dilatonic and single-charged STU black holes as two concrete examples, and compute the flows of conductivity and diffusion coefficient by solving the linear order perturbation equations. We then check the consistence by evaluating the Brown-York tensor at a finite radial position. Finally, we find that the retarded Green functions for the shear modes can be expressed easily in terms of black hole thermodynamic quantities and transport coefficients.
PubDate: Sun, 10 Aug 2014 09:04:26 +000
- Rough Mirror as a Quantum State Selector: Analysis and Design
Abstract: We report analysis of rough mirrors used as the gravitational state selectors in neutron beam and similar experiments. The key to mirror properties is its roughness correlation function (CF) which is extracted from the precision optical scanning measurements of the surface profile. To identify CF in the presence of fluctuation-driven fat tails, we perform numerical experiments with computer-generated random surfaces with the known CF. These numerical experiments provide a reliable identification procedure which we apply to the actual rough mirror. The extracted CF allows us to make predictions for ongoing GRANIT experiments. We also propose a radically new design for rough mirrors based on Monte Carlo simulations for the 1D Ising model. The implementation of this design provides a controlled environment with predictable scattering properties.
PubDate: Mon, 04 Aug 2014 11:42:13 +000
- Performance of Water-Based Liquid Scintillator: An Independent Analysis
Abstract: The water-based liquid scintillator (WbLS) is a new material currently under development. It is based on the idea of dissolving the organic scintillator in water using special surfactants. This material strives to achieve the novel detection techniques by combining the Cerenkov rings and scintillation light, as well as the total cost reduction compared to pure liquid scintillator (LS). The independent light yield measurement analysis for the light yield measurements using three different proton beam energies (210 MeV, 475 MeV, and 2000 MeV) for water, two different WbLS formulations (0.4% and 0.99%), and pure LS conducted at Brookhaven National Laboratory, USA, is presented. The results show that a goal of ~100 optical photons/MeV, indicated by the simulation to be an optimal light yield for observing both the Cerenkov ring and the scintillation light from the proton decay in a large water detector, has been achieved.
PubDate: Thu, 24 Jul 2014 11:39:57 +000
- Quantized Ultracold Neutrons in Rough Waveguides: GRANIT Experiments and
Abstract: We apply our general theory of transport in systems with random rough boundaries to gravitationally quantized ultracold neutrons in rough waveguides as in GRANIT experiments (ILL, Grenoble). We consider waveguides with roughness in both two and one dimensions (2D and 1D). In the biased diffusion approximation the depletion times for the gravitational quantum states can be easily expressed via each other irrespective of the system parameters. The calculation of the exit neutron count reduces to evaluation of a single constant which contains a complicated integral of the correlation function of surface roughness. In the case of 1D roughness (random grating) this constant is calculated analytically for common types of the correlation functions. The results obey simple scaling relations which are slightly different in 1D and 2D. We predict the exit neutron count for the new GRANIT cell.
PubDate: Wed, 23 Jul 2014 09:27:48 +000
- In-Pile 4He Source for UCN Production at the ESS
Abstract: ESS will be a premier neutron source facility. Unprecedented neutron beam intensities are ensured by spallation reactions of a 5 MW, 2.0 GeV proton beam impinging on a tungsten target equipped with advanced moderators. The work presented here aims at investigating possibilities for installing an ultra cold neutron (UCN) source at the ESS. One consequence of using the recently proposed flat moderators is that they take up less space than the moderators originally foreseen and thus leave more freedom to design a UCN source, close to the spallation hotspot. One of the options studied is to place a large 4He UCN source in a through-going tube which penetrates the shielding below the target. First calculations of neutron flux available for UCN production are given, along with heat-load estimates. It is estimated that the flux can give rise to a UCN production at a rate of up to UCN/s. A production in this range potentially allows for a number of UCN experiments to be carried out at unprecedented precision, including, for example, quantum gravitational spectroscopy with UCNs which rely on high phase-space density.
PubDate: Wed, 23 Jul 2014 08:26:15 +000
- Proposal to Search for a Dark Photon in Positron on Target Collisions at
Abstract: Photon-like particles are predicted in many extensions of the Standard Model. They have interactions similar to the photon, are vector bosons, and can be produced together with photons. The present paper proposes a search for such particles in the process in a positron-on-target experiment, exploiting the positron beam of the DANE linac at the Laboratori Nazionali di Frascati, INFN. In one year of running a sensitivity in the relative interaction strength down to ~10−6 is achievable, in the mass region from 2.5 MeV. The proposed experimental setup and the analysis technique are discussed.
PubDate: Tue, 22 Jul 2014 12:04:23 +000
- Heavy Scalar, Vector, and Axial-Vector Mesons in Hot and Dense Nuclear
Abstract: In this work we shall investigate the mass modifications of scalar mesons (; ), vector mesons (; ), and axial-vector mesons (; ) at finite density and temperature of the nuclear medium. The above mesons are modified in the nuclear medium through the modification of quark and gluon condensates. We will find the medium modification of quark and gluon condensates within chiral SU(3) model through the medium modification of scalar-isoscalar fields and at finite density and temperature. These medium modified quark and gluon condensates will further be used through QCD sum rules for the evaluation of in-medium properties of the above mentioned scalar, vector, and axial vector mesons. We will also discuss the effects of density and temperature of the nuclear medium on the scattering lengths of the above scalar, vector, and axial-vector mesons. The study of the medium modifications of the above mesons may be helpful for understanding their production rates in heavy-ion collision experiments. The results of present investigations of medium modifications of scalar, vector, and axial-vector mesons at finite density and temperature can be verified in the compressed baryonic matter (CBM) experiment of FAIR facility at GSI, Germany.
PubDate: Tue, 22 Jul 2014 11:23:37 +000
- Emission of Protons and Charged Pions in p + Cu and p + Pb Collisions at
3, 8, and 15 GeV/c
Abstract: We present an analysis of proton and charged pion transverse momentum spectra of and reactions at 3, 8, and 15 GeV/c in the framework of a multisource thermal model. The spectra are compared closely with the experimental data of HARP-CDP at all angular intervals. The result shows that the widths of the particle distributions in both and collisions decrease with increasing the angle for the same incident momentum.
PubDate: Sun, 20 Jul 2014 06:28:10 +000
- Common Behaviors of Spinor-Type Instantons in 2D Thirring and 4D Gursey
Abstract: We investigate two examples of conformal invariant pure spinor fermionic models, which admit particle-like solutions of the classical field equations. For different dimensions and quantum spinor numbers, the vector field visualizations of the models are constructed to provide a better understanding of the spinor-type instanton dynamics in phase space. The hierarchical cluster analysis method investigations of the models are also presented. Finally, the autocorrelation and power spectrum graphs of models are constructed and frequencies of motions are defined.
PubDate: Thu, 17 Jul 2014 10:07:40 +000
- On Finite Interquark Potential in Driven by a Minimal Length
Abstract: We address the effect of a quantum gravity induced minimal length on a physical observable for three-dimensional Yang-Mills. Our calculation is done within stationary perturbation theory. Interestingly enough, we find an ultraviolet finite interaction energy, which contains a regularized logarithmic function and a linear confining potential. This result highlights the role played by the new quantum of length in our discussion.
PubDate: Thu, 17 Jul 2014 00:00:00 +000
- Gaseous Detector with Sub-keV Threshold to Study Neutrino Scattering at
Low Recoil Energies
Abstract: Gaseous detector with a sub-keV electron equivalent threshold is a very perspective tool for the precision measurement of the neutrino magnetic moment and for observing coherent scattering of neutrinos on nuclei. The progress in the development of low noise electronics makes it possible to register the rare events at the threshold less than 100 eV. The construction of the gaseous detector is given and the typical pulses with amplitudes of a few eV observed on a bench scale installation are presented. The possible implications for future experiments are discussed.
PubDate: Tue, 15 Jul 2014 12:27:49 +000
- Scattering and Bound States of Duffin-Kemmer-Petiau Particles for
-Parameter Hyperbolic Pöschl-Teller Potential
Abstract: The Duffin-Kemmer-Petiau (DKP) equation in the presence of a scalar potential is solved in one spatial dimension for the vector -parameter Hyperbolic Pöschl-Teller (HPT) potential. In obtaining complete solutions we used the weak interaction approach and took the scalar and vector potentials in a correlated form. By looking at the asymptotic behaviors of the solutions, we identify the bound and scattering states. We calculate transmission () and reflection () probability densities and analyze their dependence on the potential shape parameters. Also we investigate the dependence of energy eigenvalues of the bound states on the potential shape parameters.
PubDate: Mon, 14 Jul 2014 12:11:09 +000
- Theory of Neutrino-Atom Collisions: The History, Present Status, and BSM
Abstract: An overview of the current theoretical studies on neutrino-atom scattering processes is presented. The ionization channel of these processes, which is studied in experiments searching for neutrino magnetic moments, is brought into focus. Recent developments in the theory of atomic ionization by impact of reactor antineutrinos are discussed. It is shown that the stepping approximation is well applicable for the data analysis practically down to the ionization threshold.
PubDate: Thu, 10 Jul 2014 08:42:21 +000