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]
- Astrophysical Aspects of Neutrino Dynamics in Ultradegenerate Quark Gluon
Abstract: The cardinal focus of the present review is to explore the role of neutrinos originating from the ultradense core of neutron stars composed of quark gluon plasma in the astrophysical scenario. The collective excitations of the quarks involving the neutrinos through the different kinematical processes have been studied. The cooling of the neutron stars as well as pulsar kicks due to asymmetric neutrino emission has been discussed in detail. Results involving calculation of relevant physical quantities like neutrino mean free path and emissivity have been presented in the framework of non-Fermi liquid behavior as applicable to ultradegenerate plasma.
PubDate: Thu, 16 Mar 2017 00:00:00 +000
- Searches for the Anomalous FCNC Top-Higgs Couplings with Polarized
Electron Beam at the LHeC
Abstract: We study the single top and Higgs associated production in the top-Higgs FCNC couplings at the LHeC with the electron beam energy of GeV and GeV and combination of a 7 TeV and 50 TeV proton beam. With the possibility of -beam polarization (, ), we distinct the cut-based method and the multivariate analysis- (MVA-) based method and compare with the current experimental and theoretical limits. It is shown that the branching ratio can be probed to 0.113 (0.093%), 0.071 (0.057%), 0.030 (0.022%), and 0.024 (0.019%) with the cut-based (MVA-based) analysis at (, ) = (7 TeV, 60 GeV), (, ) = (7 TeV, 120 GeV), (, ) = (50 TeV, 60 GeV), and (, ) = (50 TeV, 120 GeV) beam energy and 1 level. With the possibility of -beam polarization, the expected limits can be probed down to 0.090 (0.073%), 0.056 (0.045%), 0.024 (0.018%), and 0.019 (0.015%), respectively.
PubDate: Thu, 16 Mar 2017 00:00:00 +000
- Mass of the Stabilized Radion in the Limit of Finite Quartic Coupling
Abstract: We present an exact treatment of the modulus stabilization condition with the general boundary conditions of the bulk scalar field in the Randall-Sundrum model. We find analytical expressions for the value of the modulus and the mass of the radion.
PubDate: Sun, 12 Mar 2017 00:00:00 +000
- Predictions for the Isolated Prompt Photon Production at the LHC at =
Abstract: The prompt photon production in hadronic collisions has a long history of providing information on the substructure of hadrons and testing the perturbative techniques of QCD. Some valuable information about the parton densities in the nucleon and nuclei, especially of the gluon, can also be achieved by analysing the measurements of the prompt photon production cross section whether inclusively or in association with heavy quarks or jets. In this work, we present predictions for the inclusive isolated prompt photon production in pp collisions at center-of-mass energy of 13 TeV using various modern PDF sets. The calculations are presented as a function of both photon transverse energy and pseudorapidity for the ATLAS kinematic coverage. We also study in detail the theoretical uncertainty in the cross sections due to the variation of the renormalization, factorization, and fragmentation scales. Moreover, we introduce and calculate the ratios of photon momenta for different rapidity regions and study the impact of various input PDFs on such quantity.
PubDate: Sun, 12 Mar 2017 00:00:00 +000
- (Anti)chiral Superfield Approach to Nilpotent Symmetries: Self-Dual Chiral
Abstract: We exploit the beauty and strength of the symmetry invariant restrictions on the (anti)chiral superfields to derive the Becchi-Rouet-Stora-Tyutin (BRST), anti-BRST, and (anti-)co-BRST symmetry transformations in the case of a two -dimensional (2) self-dual chiral bosonic field theory within the framework of augmented (anti)chiral superfield formalism. Our 2 ordinary theory is generalized onto a -dimensional supermanifold which is parameterized by the superspace variable , where (with ) are the ordinary 2 bosonic coordinates and () are a pair of Grassmannian variables with their standard relationships: , . We impose the (anti-)BRST and (anti-)co-BRST invariant restrictions on the (anti)chiral superfields (defined on the (anti)chiral -dimensional supersubmanifolds of the above general -dimensional supermanifold) to derive the above nilpotent symmetries. We do not exploit the mathematical strength of the (dual-)horizontality conditions anywhere in our present investigation. We also discuss the properties of nilpotency, absolute anticommutativity, and (anti-)BRST and (anti-)co-BRST symmetry invariance of the Lagrangian density within the framework of our augmented (anti)chiral superfield formalism. Our observation of the absolute anticommutativity property is a completely novel result in view of the fact that we have considered only the (anti)chiral superfields in our present endeavor.
PubDate: Tue, 07 Mar 2017 00:00:00 +000
- Cylindrically Symmetric, Asymptotically Flat, Petrov Type D Spacetime with
a Naked Curvature Singularity and Matter Collapse
Abstract: We present a cylindrically symmetric, Petrov type D, nonexpanding, shear-free, and vorticity-free solution of Einstein’s field equations. The spacetime is asymptotically flat radially and regular everywhere except on the symmetry axis where it possesses a naked curvature singularity. The energy-momentum tensor of the spacetime is that for an anisotropic fluid which satisfies the different energy conditions. This spacetime is used to generate a rotating spacetime which admits closed timelike curves and may represent a Cosmic Time Machine.
PubDate: Mon, 06 Mar 2017 06:41:10 +000
- Heavy Quark Potential with Hyperscaling Violation
Abstract: We investigate the behavior of the heavy quark potential in the backgrounds with hyperscaling violation. The metrics are covariant under a generalized Lifshitz scaling symmetry with the dynamical Lifshitz parameter and hyperscaling violation exponent . We calculate the potential for a certain range of and and discuss how it changes in the presence of the two parameters. Moreover, we add a constant electric field to the backgrounds and study its effects on the potential. It is shown that the heavy quark potential depends on the nonrelativistic parameters. Also, the presence of the constant electric field tends to increase the potential.
PubDate: Mon, 06 Mar 2017 00:00:00 +000
- Quantum Radiation Properties of General Nonstationary Black Hole
Abstract: Using the generalized tortoise coordinate transformations the quantum radiation properties of Klein-Gordon scalar particles, Maxwell’s electromagnetic field equations, and Dirac equations are investigated in general nonstationary black hole. The locations of the event horizon and the Hawking temperature depend on both time and angles. A new extra coupling effect is observed in the thermal radiation spectrum of Maxwell’s equations and Dirac equations which is absent in the thermal radiation spectrum of scalar particles. We also observe that the chemical potential derived from scalar particles is equal to the highest energy of the negative-energy state of the scalar particle in the nonthermal radiation in general nonstationary black hole. Applying generalized tortoise coordinate transformation a constant term is produced in the expression of thermal radiation in general nonstationary black hole. It indicates that generalized tortoise coordinate transformation is more accurate and reliable in the study of thermal radiation of black hole.
PubDate: Sun, 05 Mar 2017 00:00:00 +000
- Mimetic Gravity: A Review of Recent Developments and Applications to
Cosmology and Astrophysics
Abstract: Mimetic gravity is a Weyl-symmetric extension of General Relativity, related to the latter by a singular disformal transformation, wherein the appearance of a dust-like perfect fluid can mimic cold dark matter at a cosmological level. Within this framework, it is possible to provide a unified geometrical explanation for dark matter, the late-time acceleration, and inflation, making it a very attractive theory. In this review, we summarize the main aspects of mimetic gravity, as well as extensions of the minimal formulation of the model. We devote particular focus to the reconstruction technique, which allows the realization of any desired expansionary history of the universe by an accurate choice of potential or other functions defined within the theory (as in the case of mimetic gravity). We briefly discuss cosmological perturbation theory within mimetic gravity. As a case study within which we apply the concepts previously discussed, we study a mimetic Hořava-like theory, of which we explore solutions and cosmological perturbations in detail. Finally, we conclude the review by discussing static spherically symmetric solutions within mimetic gravity and apply our findings to the problem of galactic rotation curves. Our review provides an introduction to mimetic gravity, as well as a concise but self-contained summary of recent findings, progress, open questions, and outlooks on future research directions.
PubDate: Thu, 02 Mar 2017 07:56:43 +000
- Lie Symmetry and the Bethe Ansatz Solution of a New Quasi-Exactly Solvable
Abstract: We study the Schrödinger equation with a new quasi-exactly solvable double-well potential. Exact expressions for the energies, the corresponding wave functions, and the allowed values of the potential parameters are obtained using two different methods, the Bethe ansatz method and the Lie algebraic approach. Some numerical results are reported and it is shown that the results are in good agreement with each other and with those obtained previously via a different method.
PubDate: Thu, 02 Mar 2017 00:00:00 +000
- Ring-Shaped Potential and a Class of Relevant Integrals Involved Universal
Associated Legendre Polynomials with Complicated Arguments
Abstract: We find that the solution of the polar angular differential equation can be written as the universal associated Legendre polynomials. Its generating function is applied to obtain an analytical result for a class of interesting integrals involving complicated argument, that is, , where . The present method can in principle be generalizable to the integrals involving other special functions. As an illustration we also study a typical Bessel integral with a complicated argument .
PubDate: Sun, 26 Feb 2017 13:49:10 +000
- Renormalization of Chiral Nuclear Forces with Multiple Subtractions in
Abstract: We analyse the renormalization of the of two-nucleon interaction with multiple subtractions in peripheral waves considering two chiral forces at N3LO. Phase shifts at low energies are then computed with several subtraction points below fm−1. We show that for most peripheral waves the phase shifts have nearly no dependence on the renormalization scale. In two cases the phase shifts converge slowly as the renormalization scale approaches fm−1 and in one case the phase shifts presented oscillations with respect to the subtraction point .
PubDate: Sun, 26 Feb 2017 06:41:05 +000
- On the Frequency Distribution of Neutral Particles from Low-Energy Strong
Abstract: The rejection of the contamination, or background, from low-energy strong interactions at hadron collider experiments is a topic that has received significant attention in the field of particle physics. This article builds on a particle-level view of collision events, in line with recently proposed subtraction methods. While conventional techniques in the field usually concentrate on probability distributions, our study is, to our knowledge, the first attempt at estimating the frequency distribution of background particles across the kinematic space inside individual collision events. In fact, while the probability distribution can generally be estimated given a model of low-energy strong interactions, the corresponding frequency distribution inside a single event typically deviates from the average and cannot be predicted a priori. We present preliminary results in this direction and establish a connection between our technique and the particle weighting methods that have been the subject of recent investigation at the Large Hadron Collider.
PubDate: Wed, 22 Feb 2017 08:39:53 +000
- Charmonium Mass Spectrum with Spin-Dependent Interaction in
Abstract: In this paper we have solved the nonrelativistic form of the Lippmann-Schwinger equation in the momentum-helicity space by inserting a spin-dependent quark-antiquark potential model numerically. To this end, we have used the momentum-helicity basis states for describing a nonrelativistic reduction of one-gluon exchange potential. Then we have calculated the mass spectrum of the charmonium , and finally we have compared the results with the other theoretical results and experimental data.
PubDate: Tue, 21 Feb 2017 09:55:24 +000
- A Specific Supersymmetric Quantum Mechanical Model: Supervariable Approach
Abstract: By exploiting the supersymmetric invariant restrictions on the chiral and antichiral supervariables, we derive the off-shell nilpotent symmetry transformations for a specific (0 + 1)-dimensional supersymmetric quantum mechanical model which is considered on a (1, 2)-dimensional supermanifold (parametrized by a bosonic variable and a pair of Grassmannian variables ()). We also provide the geometrical meaning to the symmetry transformations. Finally, we show that this specific SUSY quantum mechanical model is a model for Hodge theory.
PubDate: Sun, 19 Feb 2017 00:00:00 +000
- 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