Advances in High Energy Physics
[SJR: 0.892] [H-I: 19] [21 followers] Follow
Open Access journal
ISSN (Print) 1687-7357 - ISSN (Online) 1687-7365
Published by Hindawi [333 journals]
- Gravitational Quasinormal Modes of Regular Phantom Black Hole
Abstract: We investigate the gravitational quasinormal modes (QNMs) for a type of regular black hole (BH) known as phantom BH, which is a static self-gravitating solution of a minimally coupled phantom scalar field with a potential. The studies are carried out for three different spacetimes: asymptotically flat, de Sitter (dS), and anti-de Sitter (AdS). In order to consider the standard odd parity and even parity of gravitational perturbations, the corresponding master equations are derived. The QNMs are discussed by evaluating the temporal evolution of the perturbation field which, in turn, provides direct information on the stability of BH spacetime. It is found that in asymptotically flat, dS, and AdS spacetimes the gravitational perturbations have similar characteristics for both odd and even parities. The decay rate of perturbation is strongly dependent on the scale parameter , which measures the coupling strength between phantom scalar field and the gravity. Furthermore, through the analysis of Hawking radiation, it is shown that the thermodynamics of such regular phantom BH is also influenced by . The obtained results might shed some light on the quantum interpretation of QNM perturbation.
PubDate: Thu, 16 Feb 2017 00:00:00 +000
- Phenomenological Aspects of Quantum Gravity and Modified Theories of
PubDate: Wed, 15 Feb 2017 00:00:00 +000
- On Quasinormal Modes for Scalar Perturbations of Static Spherically
Symmetric Black Holes in Nash Embedding Framework
Abstract: In this paper we investigate scalar perturbations of black holes embedded in a five-dimensional bulk space. The quasinormal frequencies of such black holes are calculated using the third order of Wentzel, Kramers, and Brillouin (WKB) approximation for scalar perturbations. The high overtones of quasinormal modes indicate a resonant-like set of black holes suggesting a serious constraint of embedding models in five dimensions.
PubDate: Tue, 14 Feb 2017 10:23:04 +000
- Mirror Nuclei of 17O and 17F in Relativistic and Nonrelativistic Shell
Abstract: We have investigated energy levels mirror nuclei of the 17O and 17F in relativistic and nonrelativistic shell model. The nuclei 17O and 17F can be modeled as a doubly magic 17O = n + (N = Z = 8) and 17F = p + (N = Z = 8), with one additional nucleon (valence) in the ld5/2 level. Then we have selected the quadratic Hellmann potential for interaction between core and single nucleon. Using Parametric Nikiforov-Uvarov method, we have calculated the energy levels and wave function in Dirac and Schrodinger equations for relativistic and nonrelativistic, respectively. Finally, we have computed the binding and excited energy levels for mirror nuclei of 17O and 17F and compare with other works. Our results were in agreement with experimental values and hence this model could be applied for similar nuclei.
PubDate: Tue, 14 Feb 2017 00:00:00 +000
- Effect of Strong Magnetic Field on Competing Order Parameters in
Two-Flavor Dense Quark Matter
Abstract: We study the effect of strong magnetic field on competing chiral and diquark order parameters in a regime of moderately dense quark matter. The interdependence of the chiral and diquark condensates through nonperturbative quark mass and strong coupling effects is analyzed in a two-flavor Nambu-Jona-Lasinio (NJL) model. In the weak magnetic field limit, our results agree qualitatively with earlier zero-field studies in the literature that find a critical coupling ratio below which chiral or superconducting order parameters appear almost exclusively. Above the critical ratio, there exists a significant mixed broken phase region where both gaps are nonzero. However, a strong magnetic field G disrupts this mixed broken phase region and changes a smooth crossover found in the weak-field case to a first-order transition for both gaps at almost the same critical density. Our results suggest that in the two-flavor approximation to moderately dense quark matter strong magnetic field enhances the possibility of a mixed phase at high density, with implications for the structure, energetics, and vibrational spectrum of neutron stars.
PubDate: Tue, 14 Feb 2017 00:00:00 +000
- Neutrino Masses and Oscillations 2015
PubDate: Mon, 13 Feb 2017 11:54:48 +000
- An Experiment and Detection Scheme for Cavity-Based Light Cold Dark Matter
Abstract: A resonance detection scheme and some useful ideas for cavity-based searches of light cold dark matter particles (such as axions) are presented, as an effort to aid in the on-going endeavors in this direction as well as for future experiments, especially in possibly developing a table-top experiment. The scheme is based on our idea of a resonant detector, incorporating an integrated tunnel diode (TD) and GaAs HEMT/HFET (High-Electron Mobility Transistor/Heterogeneous FET) transistor amplifier, weakly coupled to a cavity in a strong transverse magnetic field. The TD-amplifier combination is suggested as a sensitive and simple technique to facilitate resonance detection within the cavity while maintaining excellent noise performance, whereas our proposed Halbach magnet array could serve as a low-noise and permanent solution replacing the conventional electromagnets scheme. We present some preliminary test results which demonstrate resonance detection from simulated test signals in a small optimal axion mass range with superior signal-to-noise ratios (SNR). Our suggested design also contains an overview of a simpler on-resonance dc signal read-out scheme replacing the complicated heterodyne read-out. We believe that all these factors and our propositions could possibly improve or at least simplify the resonance detection and read-out in cavity-based DM particle detection searches (and other spectroscopy applications) and reduce the complications (and associated costs), in addition to reducing the electromagnetic interference and background.
PubDate: Mon, 13 Feb 2017 00:00:00 +000
- Two-Center Gaussian Potential Well for Studying Light Nucleus in Cluster
Abstract: The clustering phenomena are very important to determine structure of light nuclei and deformation of spherical shape is inevitable. Hence, we calculated the energy levels of two-center Gaussian potential well including spin-orbit coupling by solving the Schrödinger equation in the cylindrical coordinates. This model can predict the spin and parity of the light nuclei that have two identical cluster structures.
PubDate: Sun, 12 Feb 2017 00:00:00 +000
- Bose-Einstein Condensate Dark Matter Halos Confronted with Galactic
Abstract: We present a comparative confrontation of both the Bose-Einstein Condensate (BEC) and the Navarro-Frenk-White (NFW) dark halo models with galactic rotation curves. We employ 6 High Surface Brightness (HSB), 6 Low Surface Brightness (LSB), and 7 dwarf galaxies with rotation curves falling into two classes. In the first class rotational velocities increase with radius over the observed range. The BEC and NFW models give comparable fits for HSB and LSB galaxies of this type, while for dwarf galaxies the fit is significantly better with the BEC model. In the second class the rotational velocity of HSB and LSB galaxies exhibits long flat plateaus, resulting in better fit with the NFW model for HSB galaxies and comparable fits for LSB galaxies. We conclude that due to its central density cusp avoidance the BEC model fits better dwarf galaxy dark matter distribution. Nevertheless it suffers from sharp cutoff in larger galaxies, where the NFW model performs better. The investigated galaxy sample obeys the Tully-Fisher relation, including the particular characteristics exhibited by dwarf galaxies. In both models the fitting enforces a relation between dark matter parameters: the characteristic density and the corresponding characteristic distance scale with an inverse power.
PubDate: Wed, 08 Feb 2017 07:40:12 +000
- Sources of Charged Higgs Pair through Double or Triple Higgs Production at
Abstract: The production of triple Higgs , and pairwise charged Higgs boson is studied in the context of future linear colliders within the two-Higgs-doublet model (2HDM) type II. The aim is to compare sources of charged Higgs pair through the above processes, that is, double and triple Higgs production. Cross sections are calculated at the leading order in 2HDM type II and Minimal Supersymmetric Standard Model (MSSM). Several orders of magnitude (104) enhancement are observed in 2HDM compared to MSSM, while no sizable enhancement is seen in muon collider versus electron-positron collider. The analysis is based on a heavy charged Higgs with mass above 500 GeV. It is found that double charged Higgs production cross section (being the same in 2HDM and MSSM) is few femtobarns, while the triple Higgs production cannot exceed a fraction of femtobarn within the parameter space under study.
PubDate: Wed, 08 Feb 2017 00:00:00 +000
- Bounds on the Electromagnetic Dipole Moments through the Single Top
Production at the CLIC
Abstract: We obtain bounds on the anomalous magnetic and electric dipole moments of the -quark from a future high-energy and high-luminosity linear electron positron collider, as the CLIC, with polarized and unpolarized electron beams which are powerful tools for determining new physics. We consider the processes ( is the Compton backscattering photon) and ( is the Weizsacker-Williams photon) as they are one of the most important sources of single top quark production. For systematic uncertainties of , , center-of-mass energy of , and integrated luminosity of the future collider may put bounds on the electromagnetic dipole moments and of the top quark of the order of at the level, which are competitive with those recently reported in previous studies at hadron colliders and the ILC.
PubDate: Mon, 06 Feb 2017 07:44:54 +000
- Finite Temperature QCD Sum Rules: A Review
Abstract: The method of QCD sum rules at finite temperature is reviewed, with emphasis on recent results. These include predictions for the survival of charmonium and bottonium states, at and beyond the critical temperature for deconfinement, as later confirmed by lattice QCD simulations. Also included are determinations in the light-quark vector and axial-vector channels, allowing analysing the Weinberg sum rules and predicting the dimuon spectrum in heavy-ion collisions in the region of the rho-meson. Also, in this sector, the determination of the temperature behaviour of the up-down quark mass, together with the pion decay constant, will be described. Finally, an extension of the QCD sum rule method to incorporate finite baryon chemical potential is reviewed.
PubDate: Sun, 05 Feb 2017 14:22:41 +000
- Relativistic Energies and Scattering Phase Shifts for the Fermionic
Particles Scattered by Hyperbolical Potential with the Pseudo(spin)
Abstract: In this paper, we studied the approximate scattering state solutions of the Dirac equation with the hyperbolical potential with pseudospin and spin symmetries. By applying an improved Greene-Aldrich approximation scheme within the formalism of functional analytical method, we obtained the spin-orbit quantum numbers dependent scattering phase shifts for the spin and pseudospin symmetries. The normalization constants, lower and upper radial spinor for the two symmetries, and the relativistic energy spectra were presented. Our results reveal that both the symmetry constants ( and ) and the spin-orbit quantum number affect scattering phase shifts significantly.
PubDate: Sun, 05 Feb 2017 07:43:16 +000
- Scattering and Bound States of a Spin-1/2 Neutral Particle in the Cosmic
Abstract: In this paper the relativistic quantum dynamics of a spin-1/2 neutral particle with a magnetic moment in the cosmic string spacetime is reexamined by applying the von Neumann theory of self-adjoint extensions. Contrary to previous studies where the interaction between the spin and the line of charge is neglected, here we consider its effects. This interaction gives rise to a point interaction: . Due to the presence of the Dirac delta function, by applying an appropriated boundary condition provided by the theory of self-adjoint extensions, irregular solutions for the Hamiltonian are allowed. We address the scattering problem obtaining the phase shift, -matrix, and the scattering amplitude. The scattering amplitude obtained shows a dependency with energy which stems from the fact that the helicity is not conserved in this system. Examining the poles of the -matrix we obtain an expression for the bound states. The presence of bound states for this system has not been discussed before in the literature.
PubDate: Tue, 31 Jan 2017 13:23:44 +000
- Black Hole Solution of Einstein-Born-Infeld-Yang-Mills Theory
Abstract: A new four-dimensional black hole solution of Einstein-Born-Infeld-Yang-Mills theory is constructed; several degenerated forms of the black hole solution are presented. The related thermodynamical quantities are calculated, with which the first law of thermodynamics is checked to be satisfied. Identifying the cosmological constant as pressure of the system, the phase transition behaviors of the black hole in the extended phase space are studied.
PubDate: Tue, 31 Jan 2017 07:55:25 +000
- Dirac Field as a Source of the Inflation in Dimensional Teleparallel
Abstract: In this paper, we study early-time inflation and late-time acceleration of the universe by nonminimally coupling the Dirac field with torsion in the spatially flat Friedman-Robertson-Walker (FRW) cosmological model background. The results obtained by the Noether symmetry approach with and without a gauge term are compared. Additionally, we compare these results with that of the dimensional teleparallel gravity under Noether symmetry approach. And we see that the study explains early-time inflation and late-time acceleration of the universe.
PubDate: Tue, 31 Jan 2017 00:00:00 +000
- Proposed Economical and Stable Lepton Mass Matrices with Texture Zeros
Abstract: There are many viable combinations of texture zeros in lepton mass matrices. We propose an economical and stable mass texture. Analytical and numerical results on mixing parameters and the effective mass of neutrinos are obtained. These results satisfy new constraints from neutrinos oscillation experiments and cosmological observations. Their stabilities are also examined through the perturbations to some structure parameters. Our proposition reveals that, in the complex forest of neutrinos mixing models, a simple and stable one is still possible.
PubDate: Mon, 30 Jan 2017 11:33:10 +000
- An Analysis of a Minimal Vectorlike Extension of the Standard Model
Abstract: We analyze an extension of the Standard Model with an additional hypercolor gauge group keeping the Higgs boson as a fundamental field. Vectorlike interactions of new hyperquarks with the intermediate vector bosons are explicitly constructed. We also consider pseudo-Nambu–Goldstone bosons caused by the symmetry breaking . A specific global symmetry of the model with zero hypercharge of the hyperquark doublets ensures the stability of a neutral pseudoscalar field. Some possible manifestations of the lightest states at colliders are also examined.
PubDate: Sun, 29 Jan 2017 09:36:30 +000
- Solution of Effective-Mass Dirac Equation with Scalar-Vector and
Pseudoscalar Terms for Generalized Hulthén Potential
Abstract: We find the exact bound state solutions and normalization constant for the Dirac equation with scalar-vector-pseudoscalar interaction terms for the generalized Hulthén potential in the case where we have a particular mass function . We also search the solutions for the constant mass where the obtained results correspond to the ones when the Dirac equation has spin and pseudospin symmetry, respectively. After giving the obtained results for the nonrelativistic case, we search then the energy spectra and corresponding upper and lower components of Dirac spinor for the case of PT-symmetric forms of the present potential.
PubDate: Tue, 24 Jan 2017 08:53:03 +000
- Thermodynamics of the Schwarzschild-AdS Black Hole with a Minimal Length
Abstract: Using the mass-smeared scheme of black holes, we study the thermodynamics of black holes. Two interesting models are considered. One is the self-regular Schwarzschild-AdS black hole whose mass density is given by the analogue to probability densities of quantum hydrogen atoms. The other model is the same black hole but whose mass density is chosen to be a rational fractional function of radial coordinates. Both mass densities are in fact analytic expressions of the -function. We analyze the phase structures of the two models by investigating the heat capacity at constant pressure and the Gibbs free energy in an isothermal-isobaric ensemble. Both models fail to decay into the pure thermal radiation even with the positive Gibbs free energy due to the existence of a minimal length. Furthermore, we extend our analysis to a general mass-smeared form that is also associated with the -function and indicate the similar thermodynamic properties for various possible mass-smeared forms based on the -function.
PubDate: Tue, 24 Jan 2017 00:00:00 +000
- -Deformed Relativistic Fermion Scattering
Abstract: In this article, after introducing a kind of -deformation in quantum mechanics, first, -deformed form of Dirac equation in relativistic quantum mechanics is derived. Then, three important scattering problems in physics are studied. All results have satisfied what we had expected before. Furthermore, effects of all parameters in the problems on the reflection and transmission coefficients are calculated and shown graphically.
PubDate: Thu, 19 Jan 2017 00:00:00 +000
- Thermodynamics in Gravity with Nonminimal Coupling to Matter
Abstract: In the present paper, we study the thermodynamics behavior of the field equations for the generalized gravity with arbitrary coupling between matter and the torsion scalar. In this regard, we explore the verification of the first law of thermodynamics at the apparent horizon of the Friedmann-Robertson-Walker universe in two different perspectives, namely, the nonequilibrium and equilibrium descriptions of thermodynamics. Furthermore, we investigate the validity of the second law of thermodynamics for both descriptions of this scenario with the assumption that the temperature of matter inside the horizon is similar to that of horizon.
PubDate: Tue, 17 Jan 2017 14:04:38 +000
- Experimental Results on Charge Fluctuations in Heavy-Ion Collisions
Abstract: We present a subset of experimental results on charge fluctuation from the heavy-ion collisions to search for phase transition and location of critical point in the QCD phase diagram. Measurements from the heavy-ion experiments at the SPS and RHIC energies observe that total charge fluctuations increase from central to peripheral collisions. The net-charge fluctuations in terms of dynamical fluctuation measure are studied as a function of collision energy () and centrality of the collisions. The product of and shows a monotonic decrease with collision energies, which indicates that at LHC energy the fluctuations have their origin in the QGP phase. The fluctuations in terms of higher moments of net-proton, net-electric charge, and net-kaon have been measured for various . Deviations are observed in both and for net-proton multiplicity distributions from the Skellam and hadron resonance gas model for GeV. Higher moment results of the net-electric charge and net-kaon do not observe any significant nonmonotonic behavior as a function of collision energy. We also discuss the extraction of the freeze-out parameters using particle ratios and experimentally measured higher moments of net-charge fluctuations. The extracted freeze-out parameters from experimentally measured moments and lattice calculations are found to be in agreement with the results obtained from the fit of particle ratios to the thermal model calculations.
PubDate: Tue, 17 Jan 2017 00:00:00 +000
- Particle Collision Near 1 + 1-Dimensional Horava-Lifshitz Black Hole
and Naked Singularity
Abstract: The unbounded center-of-mass (CM) energy of oppositely moving colliding particles near horizon emerges also in -dimensional Horava-Lifshitz gravity. This theory has imprints of renormalizable quantum gravity characteristics in accordance with the method of simple power counting. Surprisingly the result obtained is not valid for a 1-dimensional Compton-like process between an outgoing photon and an infalling massless/massive particle. It is possible to achieve unbounded CM energy due to collision between infalling photons and particles. The source of outgoing particles may be attributed to an explosive process just outside the horizon for a black hole and the naturally repulsive character for the case of a naked singularity. It is found that absence of angular momenta in -dimension does not yield unbounded energy for collisions in the vicinity of naked singularities.
PubDate: Mon, 16 Jan 2017 00:00:00 +000
- Black Holes and Information: A New Take on an Old Paradox
Abstract: Interest in the black hole information paradox has recently been catalyzed by the newer “firewall” argument. The crux of the updated argument is that previous solutions which relied on observer complementarity are in violation of the quantum condition of monogamy of entanglement, with the prescribed remedy being to discard the equivalence principle in favor of an energy barrier (or firewall) at the black hole horizon. Differing points of view have been put forward, including the “ER = EPR” counterargument and the final-state solution, both of which can be viewed as potential resolutions to the apparent conflict between quantum monogamy and Einstein equivalence. After reviewing these recent developments, this paper argues that the ER = EPR and final-state solutions can—thanks to observer complementarity—be seen as the same resolution of the paradox but from two different perspectives: inside and outside the black hole.
PubDate: Mon, 16 Jan 2017 00:00:00 +000
- Experimental Results on Chiral Magnetic and Vortical Effects
Abstract: Various novel transport phenomena in chiral systems result from the interplay of quantum anomalies with magnetic field and vorticity in high-energy heavy-ion collisions and could survive the expansion of the fireball and be detected in experiments. Among them are the chiral magnetic effect, the chiral vortical effect, and the chiral magnetic wave, the experimental searches for which have aroused extensive interest. The goal of this review is to describe the current status of experimental studies at Relativistic Heavy-Ion Collider at BNL and the Large Hadron Collider at CERN and to outline the future work in experiment needed to eliminate the existing uncertainties in the interpretation of the data.
PubDate: Thu, 12 Jan 2017 00:00:00 +000
- Probe of the Anomalous Quartic Couplings with Beam Polarization at the
Abstract: We have investigated the anomalous quartic couplings defined by the dimension-8 operators in semileptonic decay channel of the process for unpolarized and polarized electron (positron) beam at the Compact Linear Collider. We give the 95% confidence level bounds on the anomalous , , and couplings for various values of the integrated luminosities and center-of-mass energies. The best sensitivities obtained on anomalous , , and couplings through the process with beam polarization at TeV and an integrated luminosity of are , , and , which show improvement over the current bounds.
PubDate: Wed, 11 Jan 2017 07:01:31 +000
- The Production of Neutral Resonance with Hidden Beauty from Scattering
Abstract: We investigate the discovery potential of the predicted neutral hidden beauty resonance through scattering within an effective Lagrangian approach. Two reactions and are studied in this work, with nucleon pole exchange as the background. It is found that the contributions of the resonance give clear peak structures in the magnitude of 1 near the threshold of in the total cross sections. The numerical results indicate that the center of mass energy GeV would be the best energy window for searching the resonance, where the signal can be easily distinguished from the background. The COMPASS experiment at CERN’s Super Proton Synchrotron (SPS) with pion beam of ≃280 GeV will be an ideal platform for searching the super-heavy resonance with hidden beauty, which is promising for testing the theoretical results.
PubDate: Tue, 03 Jan 2017 10:41:25 +000
- Analysis of Radial Excitations of Octet Baryons in QCD Sum Rules
Abstract: Using the QCD sum rules method, we estimate the mass and residues of the first radial excitations of octet baryons. The contributions coming from the ground state baryons are eliminated by constructing the linear combinations of the sum rules corresponding to different Lorentz structures. Our predictions of the masses of the first radial excitations of octet baryons are in good agreement with the data.
PubDate: Tue, 03 Jan 2017 08:32:39 +000
- Lévy Distributions for One-Dimensional Analysis of the
Abstract: A general study of relations between the parameters of two centrally symmetric Lévy distributions, often used for one-dimensional investigation of Bose–Einstein correlations, is given for the first time. These relations of the strength of correlations and of the radius of the emission region take into account possible various finite ranges of the Lorentz invariant four-momentum difference for two centrally symmetric Lévy distributions. In particular, special cases of the relations are investigated for Cauchy and normal (Gaussian) distributions. The mathematical formalism is verified using the recent measurements given that a generalized centrally symmetric Lévy distribution is used. The reasonable agreement is observed between estimations and experimental results for all available types of strong interaction processes and collision energies.
PubDate: Mon, 02 Jan 2017 09:30:28 +000