Advances in High Energy Physics
[SJR: 0.892] [H-I: 19] [18 followers] Follow
Open Access journal
ISSN (Print) 1687-7357 - ISSN (Online) 1687-7365
Published by Hindawi [334 journals]
- On the Jeans Theorem and the “Tolman–Oppenheimer–Volkoff Equation”
Abstract: Corda, Mosquera Cuesta, and Lorduy Gòmez have shown that spherically symmetric stationary states can be used as a model for galaxies in the framework of the linearized gravity. Those states could represent a partial solution to the Dark Matter Problem. Here, we discuss an improvement of this work. In fact, as the star density is a functional of the invariants of the associated Vlasov equation, we show that any of these invariants is in its turn a functional of the local energy and the angular momentum. As a consequence, the star density depends only on these two integrals of the Vlasov system. This result is known as the “Jeans theorem.” In addition, we find an analogy of the historical Tolman–Oppenheimer–Volkoff equation for the system considered in this paper. For the sake of completeness, in the final section of the paper, we consider two additional models which argue that Dark Matter could not be an essential element.
PubDate: Thu, 13 Oct 2016 06:32:41 +000
- Predicting Planck Scale and Newtonian Constant from a Yang-Mills Gauge
Theory: 1- and 2-Loop Estimates
Abstract: Recently, a model for an emergent gravity based on Yang-Mills action in Euclidian 4-dimensional spacetime was proposed. In this work we provide some 1- and 2-loop computations and show that the model can accommodate suitable predicting values for the Newtonian constant. Moreover, it is shown that the typical scale of the expected transition between the quantum and the geometrodynamical theory is consistent with Planck scale. We also provide a discussion on the cosmological constant problem.
PubDate: Wed, 12 Oct 2016 08:40:53 +000
- Ultrarelativistic Spinning Particle and a Rotating Body in External Fields
Abstract: We use the vector model of spinning particle to analyze the influence of spin-field coupling on the particle’s trajectory in ultrarelativistic regime. The Lagrangian with minimal spin-gravity interaction yields the equations equivalent to the Mathisson-Papapetrou-Tulczyjew-Dixon (MPTD) equations of a rotating body. We show that they have unsatisfactory behavior in the ultrarelativistic limit. In particular, three-dimensional acceleration of the particle becomes infinite in the limit. Therefore, we examine the nonminimal interaction through the gravimagnetic moment and show that the theory with is free of the problems detected in MPTD equations. Hence, the nonminimally interacting theory seems a more promising candidate for description of a relativistic rotating body in general relativity. Vector model in an arbitrary electromagnetic field leads to generalized Frenkel and BMT equations. If we use the usual special-relativity notions for time and distance, the maximum speed of the particle with anomalous magnetic moment in an electromagnetic field is different from the speed of light. This can be corrected assuming that the three-dimensional geometry should be defined with respect to an effective metric induced by spin-field interaction.
PubDate: Tue, 11 Oct 2016 08:23:37 +000
- Thermodynamic Analysis of the Static Spherically Symmetric Field Equations
in Rastall Theory
Abstract: The restrictions on the Rastall theory due to application of the Newtonian limit to the theory are derived. In addition, we use the zero-zero component of the Rastall field equations as well as the unified first law of thermodynamics to find the Misner-Sharp mass content confined to the event horizon of the spherically symmetric static spacetimes in the Rastall framework. The obtained relation is calculated for the Schwarzschild and de-Sitter back holes as two examples. Bearing the obtained relation for the Misner-Sharp mass in mind together with recasting the one-one component of the Rastall field equations into the form of the first law of thermodynamics, we obtain expressions for the horizon entropy and the work term. Finally, we also compare the thermodynamic quantities of system, including energy, entropy, and work, with their counterparts in the Einstein framework to have a better view about the role of the Rastall hypothesis on the thermodynamics of system.
PubDate: Mon, 10 Oct 2016 06:02:09 +000
- Einstein and Møller Energy-Momentum Complexes for a New Regular Black
Hole Solution with a Nonlinear Electrodynamics Source
Abstract: A study about the energy and momentum distributions of a new charged regular black hole solution with a nonlinear electrodynamics source is presented. The energy and momentum are calculated using the Einstein and Møller energy-momentum complexes. The results show that in both pseudotensorial prescriptions the expressions for the energy of the gravitational background depend on the mass and the charge of the black hole, an additional factor coming from the spacetime metric considered, and the radial coordinate , while in both prescriptions all the momenta vanish. Further, it is pointed out that in some limiting and particular cases the two complexes yield the same expression for the energy distribution as that obtained in the relevant literature for the Schwarzschild black hole solution.
PubDate: Sun, 09 Oct 2016 06:38:35 +000
- Dark Matter and Dark Energy Induced by Condensates
Abstract: It is shown that the vacuum condensate induced by many phenomena behaves as a perfect fluid which, under particular conditions, has zero or negative pressure. In particular, the condensates of thermal states of fields in curved space and of mixed particles have been analyzed. It is shown that the thermal states with the cosmic microwave radiation temperature and the Unruh and the Hawking radiations give negligible contributions to the critical energy density of the universe, while the thermal vacuum of the intercluster medium could contribute to the dark matter, together with the vacuum energy of fields in curved space-time and of mixed neutrinos. Moreover, a component of the dark energy can be represented by the vacuum of axion-like particles mixed with photons and superpartners of neutrinos. The formal analogy among the systems characterized by the condensates can open new scenarios in the possibility of detecting the dark components of the universe in table top experiments.
PubDate: Wed, 05 Oct 2016 13:38:19 +000
- T2K and Beyond
Abstract: This paper presents the state of the art of the T2K experiment and the measurements prospects for the incoming years. After a brief description of the experiment, the most recent results will be illustrated. The observation of the electron neutrino appearance in a muon neutrino beam and the new high-precision measurements of the mixing angle by the reactor experiments have led to a reevaluation of the expected sensitivity to the oscillation parameters, relative to what was given in the original T2K proposal. For this reason the new physics potential of T2K for p.o.t. and for data exposure 3 times larger than that expected to be reachable with accelerator and beam line upgrades in 2026 before the start of operation of the next generation of long-baseline neutrino oscillation experiments will also be described in the text. In particular the last challenging scenario opens the door to the possibility of obtaining, under some conditions, a 3 measurement excluding .
PubDate: Wed, 05 Oct 2016 12:46:39 +000
- Soft Gluon Radiation off Heavy Quarks beyond Eikonal Approximation
Abstract: We calculate the soft gluon radiation spectrum off heavy quarks (HQs) interacting with light quarks (LQs) beyond small angle scattering (eikonality) approximation and thus generalize the dead-cone formula of heavy quarks extensively used in the literatures of Quark-Gluon Plasma (QGP) phenomenology to the large scattering angle regime which may be important in the energy loss of energetic heavy quarks in the deconfined Quark-Gluon Plasma medium. In the proper limits, we reproduce all the relevant existing formulae for the gluon radiation distribution off energetic quarks, heavy or light, used in the QGP phenomenology.
PubDate: Tue, 04 Oct 2016 09:55:00 +000
- Semileptonic Decays of to Light Tensor Mesons
Abstract: The semileptonic , , transitions are investigated in the frame work of the three-point QCD sum rules. Considering the quark condensate contributions, the relevant form factors of these transitions are estimated. The branching ratios of these channel modes are also calculated at different values of the continuum thresholds of the tensor mesons and compared with the obtained data for other approaches.
PubDate: Tue, 04 Oct 2016 06:58:10 +000
- An Experimental Review on Heavy-Flavor in Heavy-Ion Collision
Abstract: For over a decade now, the primary purpose of relativistic heavy-ion collisions at the Relativistic Heavy-Ion Collider (RHIC) and the Large Hadron Collider (LHC) has been to study the properties of QCD matter under extreme conditions—high temperature and high density. The heavy-ion experiments at both RHIC and LHC have recorded a wealth of data in p+p, p+Pb, d+Au, Cu+Cu, Cu+Au, Au+Au, Pb+Pb, and U+U collisions at energies ranging from GeV to 7 TeV. Heavy quarks are considered good probe to study the QCD matter created in relativistic collisions due to their very large mass and other unique properties. A precise measurement of various properties of heavy-flavor hadrons provides an insight into the fundamental properties of the hot and dense medium created in these nucleus-nucleus collisions, such as transport coefficient and thermalization and hadronization mechanisms. The main focus of this paper is to present a review on the measurements of azimuthal anisotropy of heavy-flavor hadrons and to outline the scientific opportunities in this sector due to future detector upgrade. We will mainly discuss the elliptic flow of open charmed meson (-meson), , and leptons from heavy-flavor decay at RHIC and LHC energy.
PubDate: Mon, 03 Oct 2016 13:52:34 +000
- Octant Degeneracy and Quadrant of Leptonic CPV Phase at Long Baseline
Experiments and Baryogenesis
Abstract: In a recent work by us, we have studied how CP violation discovery potential can be improved at long baseline neutrino experiments (LBNE/DUNE), by combining with its ND (near detector) and reactor experiments. In this work, we discuss how this study can be further analysed to resolve entanglement of the quadrant of leptonic CPV phase and octant of atmospheric mixing angle , at LBNEs. The study is done for both NH (normal hierarchy) and IH (inverted hierarchy), HO (higher octant), and LO (lower octant). We show how baryogenesis can enhance the effect of resolving this entanglement and how possible values of the leptonic CP violating phase can be predicted in this context. With respect to the latest global fit data of neutrino mixing angles, we predict the values of for different cases. In this context we present favoured values of ( range at ≥2σ) constrained by the latest updated BAU range and also confront our predictions of with an up-to-date global analysis of neutrino oscillation data. We find that some region of the favoured parameter space lies within the best fit values around . A detailed analytic and numerical study of baryogenesis through leptogenesis is performed in this framework within the nonsupersymmetric SO models.
PubDate: Thu, 29 Sep 2016 11:22:40 +000
- Single Top and Higgs Associated Production in the Minimal Model at the LHC
Abstract: We study the single top production in association with a Higgs boson in the extension of the Standard Model at the LHC. We calculate the production cross sections of the processes in this model. We further study the observability of the process through and find that it is still challenging for the 14 TeV LHC with high luminosity to detect this signal.
PubDate: Wed, 28 Sep 2016 09:12:36 +000
- Holographic Phase Transition Probed by Nonlocal Observables
Abstract: From the viewpoint of holography, the phase structure of a 5-dimensional Reissner-Nordström-AdS black hole is probed by the two-point correlation function, Wilson loop, and entanglement entropy. As the case of thermal entropy, we find for all the probes that the black hole undergoes a Hawking-Page phase transition, a first-order phase transition, and a second-order phase transition successively before it reaches a stable phase. In addition, for these probes, we find that the equal area law for the first-order phase transition is valid always and the critical exponent of the heat capacity for the second-order phase transition coincides with that of the mean field theory regardless of the size of the boundary region.
PubDate: Wed, 28 Sep 2016 07:03:16 +000
- A New Method for Obtaining the Baryons Mass under the Killingbeck Plus
Isotonic Oscillator Potentials
Abstract: The spectrum of ground state and excited baryons (N, Δ, Λ, Σ, , and Ω particles) has been investigated by using nonrelativistic quantum mechanics under the Killingbeck plus isotonic oscillator potentials. Using the Jacobi coordinates, anzast method, and generalized Gürsey Radicati (GR) mass formula the three-body-wave equation is solved to calculate the different states of the considered baryons. A comparison between our calculations and the available experimental data shows that the position of the Roper resonances of the nucleon, the ground states, and the excited multiplets up to three GeV are in general well reproduced. Also one can conclude that the interaction between the quark constituents of baryon resonances could be described adequately by using the combination of Killingbeck and isotonic oscillator potentials form.
PubDate: Thu, 22 Sep 2016 13:09:40 +000
- Thermodynamic Partition Function from Quantum Theory for Black Hole
Horizons in Loop Quantum Gravity
Abstract: We establish the link between the thermodynamics and the quantum theory of black hole horizons through the construction of the thermodynamic partition function, partly based on some physically plausible arguments, by beginning from the description of quantum states of the horizon, considering loop quantum gravity (LQG) as the underlying theory. Although the effective “thermalized” form of the partition function has been previously used in the literature to study the effect of thermal fluctuations of the black hole horizon, nonetheless the direct link to any existing quantum theory (which is here taken to be LQG), especially a derivation of the partition function from the quantum states of the horizon, appears to be hitherto absent. This work is an attempt to bridge this small, but essential, gap that appears to be present between the existing literature of quantum theory and thermodynamics of black holes. Furthermore, it may be emphasized that this work is only concerned with the metric independent approaches to black hole thermodynamics.
PubDate: Wed, 21 Sep 2016 14:12:15 +000
- Review of Anisotropic Flow Correlations in Ultrarelativistic Heavy-Ion
Abstract: Anisotropic flow phenomena are a key probe of the existence of Quark-Gluon Plasma. Several new observables associated with correlations between anisotropic flow harmonics are developed, which are expected to be sensitive to the initial fluctuations and transport properties of the created matter in heavy-ion collisions. I review recent developments of correlations of anisotropic flow harmonics. The experimental measurements, together with the comparisons to theoretical model calculations, open up new opportunities of exploring novel QCD dynamics in heavy-ion collisions.
PubDate: Tue, 20 Sep 2016 13:33:14 +000
- An Experimental Review on Elliptic Flow of Strange and Multistrange
Hadrons in Relativistic Heavy Ion Collisions
Abstract: Strange hadrons, especially multistrange hadrons, are good probes for the early partonic stage of heavy ion collisions due to their small hadronic cross sections. In this paper, I give a brief review on the elliptic flow measurements of strange and multistrange hadrons in relativistic heavy ion collisions at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC).
PubDate: Mon, 19 Sep 2016 13:06:49 +000
- Relativistic Energy Analysis of Five-Dimensional q-Deformed Radial
Rosen-Morse Potential Combined with q-Deformed Trigonometric Scarf
Noncentral Potential Using Asymptotic Iteration Method
Abstract: We study the exact solution of Dirac equation in the hyperspherical coordinate under influence of separable -deformed quantum potentials. The -deformed hyperbolic Rosen-Morse potential is perturbed by -deformed noncentral trigonometric Scarf potentials, where all of them can be solved by using Asymptotic Iteration Method (AIM). This work is limited to spin symmetry case. The relativistic energy equation and orbital quantum number equation have been obtained using Asymptotic Iteration Method. The upper radial wave function equations and angular wave function equations are also obtained by using this method. The relativistic energy levels are numerically calculated using Matlab, and the increase of radial quantum number causes the increase of bound state relativistic energy level in both dimensions and . The bound state relativistic energy level decreases with increasing of both deformation parameter and orbital quantum number .
PubDate: Thu, 15 Sep 2016 16:09:18 +000
- Holographic Schwinger Effect in a Confining D3-Brane Background with
Abstract: Using the AdS/CFT correspondence, we investigate the Schwinger effect in a confining D3-brane background with chemical potential. The potential between a test particle pair on the D3-brane in an external electric field is obtained. The critical field in this case is calculated. Also, we apply numerical method to evaluate the production rate for various cases. The results imply that the presence of chemical potential tends to suppress the pair production effect.
PubDate: Thu, 15 Sep 2016 07:35:41 +000
- Dynamics of an Anisotropic Universe in Theory
Abstract: Dynamics of an anisotropic universe is studied in gravity using a rescaled functional , where is the Ricci Scalar and is the trace of energy-momentum tensor. Three models have been constructed assuming a power law expansion of the universe. Physical features of the models are discussed. The model parameters are constrained from a dimensional analysis. It is found from the work that the anisotropic Bianchi type () model in the modified gravity generally favours a quintessence phase when the parameter is either or . We may not get viable models in conformity with the present day observation for .
PubDate: Wed, 14 Sep 2016 12:07:13 +000
- Large Rapidity Gap Method to Select Soft Diffraction Dissociation at the
Abstract: In proton-proton (pp) collisions, any process involves exchanging the vacuum quantum numbers is known as diffractive process. A diffractive process with no large is called soft diffractive process. The diffractive processes are important for understanding nonperturbative QCD effects and they also constitute a significant fraction of the total pp cross section. The diffractive events are typically characterized by a region of the detector without particles, known as a rapidity gap. In order to observe diffractive events in this way, we consider the pseudorapidity acceptance in the forward region of the ATLAS and CMS detectors at the Large Hadron Collider (LHC) and discuss the methods to select soft diffractive dissociation for pp collisions at TeV. It is shown that, in the limited detector rapidity acceptance, it is possible to select diffractive dissociation events by requiring a rapidity gap in the event; however, without using forward detectors, it seems not possible to fully separate single and double diffractive dissociation events. The Zero Degree Calorimeters can be used to distinguish the type of the diffractive processes up to a certain extent.
PubDate: Thu, 08 Sep 2016 17:58:44 +000
- Spectra and Elliptic Flow of (Multi)Strange Hadrons at RHIC and LHC within
Viscous Hydrodynamics + Hadron Cascade Hybrid Model
Abstract: Using the ()-dimensional ultrarelativistic viscous hydrodynamics + hadron cascade, VISHNU, hybrid model, we study the -spectra and elliptic flow of , , and in Au + Au collisions at = 200 GeV and in Pb + Pb collisions at = 2.76 TeV. Comparing our model results with the data measurements, we find that the VISHNU model gives good descriptions of the measurements of these strange and multistrange hadrons at several centrality classes at RHIC and LHC. Mass ordering of elliptic flow among , , , , , and are further investigated and discussed at the two collision systems. We find that, at both RHIC and LHC, mass ordering among , , , and is fairly reproduced within the VISHNU hybrid model, and more improvements are needed to be implemented for well describing mass ordering among , , and .
PubDate: Wed, 07 Sep 2016 11:45:15 +000
- Charged Particles Multiplicity and Scaling Violation of Fragmentation
Functions in Electron-Positron Annihilation
Abstract: By the use of data from the annihilation process of electron-positron in AMY detector at 60 GeV center of mass energy, charged particles multiplicity distribution is obtained and fitted with the KNO scaling. Then, momentum spectra of charged particles and momentum distribution with respect to the jet axis are obtained, and the results are compared to the different models of QCD; also, the distribution of fragmentation functions and scaling violations are studied. It is being expected that the scaling violations of the fragmentation functions of gluon jets are stronger than the quark ones. One of the reasons for such case is that splitting function of quarks is larger than splitting function of gluon.
PubDate: Mon, 05 Sep 2016 16:21:54 +000
- Investigation of Free Particle Propagator with Generalized Uncertainty
Abstract: We consider the Schrödinger equation with a generalized uncertainty principle for a free particle. We then transform the problem into a second-order ordinary differential equation and thereby obtain the corresponding propagator. The result of ordinary quantum mechanics is recovered for vanishing minimal length parameter.
PubDate: Thu, 01 Sep 2016 16:04:17 +000
- Israel-Stewart Approach to Viscous Dissipative Extended Holographic Ricci
Dark Energy Dominated Universe
Abstract: This paper reports a study on the truncated Israel-Stewart formalism for bulk viscosity using the extended holographic Ricci dark energy (EHRDE). Under the consideration that the universe is dominated by EHRDE, the evolution equation for the bulk viscous pressure in the framework of the truncated Israel-Stewart theory has been taken as , where is the relaxation time and is the bulk viscosity coefficient. Considering effective pressure as a sum of thermodynamic pressure of EHRDE and bulk viscous pressure, it has been observed that under the influence of bulk viscosity the EoS parameter is behaving like phantom, that is, . It has been observed that the magnitude of the effective pressure is decaying with time. We also investigated the case for a specific choice of scale factor; namely, . For this choice we have observed that a transition from quintessence to phantom is possible for the equation of state parameter. However, the CDM phase is not attainable by the state-finder trajectories for this choice. Finally it has been observed that in both of the cases the generalized second law of thermodynamics is valid for the viscous EHRDE dominated universe enveloped by the apparent horizon.
PubDate: Thu, 01 Sep 2016 13:29:34 +000
- Gravity’s Rainbow and Its Einstein Counterpart
Abstract: Motivated by UV completion of general relativity with a modification of a geometry at high energy scale, it is expected to have an energy dependent geometry. In this paper, we introduce charged black hole solutions with power Maxwell invariant source in the context of gravity’s rainbow. In addition, we investigate two classes of gravity’s rainbow solutions. At first, we study energy dependent gravity without energy-momentum tensor, and then we obtain gravity’s rainbow in the presence of conformally invariant Maxwell source. We study geometrical properties of the mentioned solutions and compare their results. We also give some related comments regarding thermodynamical behavior of the obtained solutions and discuss thermal stability of the solutions.
PubDate: Wed, 31 Aug 2016 13:01:06 +000
- Analysis of Decay in Scalar Leptoquark Model
Abstract: We analyze the baryonic semilepton decay in the scalar leptoquark models with and states, respectively. We also discuss the effects of these two NP models on some physical observables. For some measured observables, like the differential decay width, the longitudinal polarization of the dilepton system, the lepton-side forward-backward asymmetry, and the baryon-side forward-backward asymmetry, we find that the prediction values of SM are consistent with the current data in most ranges, where the prediction values of these two NP models can also keep consistent with the current data with . However, in some ranges, the prediction values of SM are difficult to meet the current data, but the contributions of these two NP models can meet them or keep close to them. For the double-lepton polarization asymmetries, , , , and are sensitive to the scalar leptoquark model but not to . However, , , , and are not sensitive to these two NP models.
PubDate: Thu, 18 Aug 2016 10:39:25 +000
- Self-Dual Configurations in a Generalized Abelian Chern-Simons-Higgs Model
with Explicit Breaking of the Lorentz Covariance
Abstract: We have studied the existence of self-dual solitonic solutions in a generalization of the Abelian Chern-Simons-Higgs model. Such a generalization introduces two different nonnegative functions, and , which split the kinetic term of the Higgs field, , breaking explicitly the Lorentz covariance. We have shown that a clean implementation of the Bogomolnyi procedure only can be implemented whether with . The self-dual or Bogomolnyi equations produce an infinity number of soliton solutions by choosing conveniently the generalizing function which must be able to provide a finite magnetic field. Also, we have shown that by properly choosing the generalizing functions it is possible to reproduce the Bogomolnyi equations of the Abelian Maxwell-Higgs and Chern-Simons-Higgs models. Finally, some new self-dual -vortex solutions have been analyzed from both theoretical and numerical point of view.
PubDate: Thu, 18 Aug 2016 08:32:43 +000
- Study of Void Probability Scaling of Singly Charged Particles Produced in
Ultrarelativistic Nuclear Collision in Fractal Scenario
Abstract: We study the fractality of void probability distribution measured in -Ag/Br interaction at an incident energy of 200 GeV per nucleon. A radically different and rigorous method called Visibility Graph analysis is used. This method is shown to reveal a strong scaling character of void probability distribution in all pseudorapidity regions. The scaling exponent, called the Power of the Scale-Freeness in Visibility Graph (PSVG), a quantitative parameter related to Hurst exponent, is strongly found to be dependent on the rapidity window size.
PubDate: Thu, 18 Aug 2016 08:29:28 +000
- Quantum-Corrected Two-Dimensional Horava-Lifshitz Black Hole Entropy
Abstract: We focus on the Hamilton-Jacobi method to determine several thermodynamic quantities such as temperature, entropy, and specific heat of two-dimensional Horava-Lifshitz black holes by using the generalized uncertainty principles (GUP). We also address the product of horizons, mainly concerning the event, Cauchy, and cosmological and virtual horizons.
PubDate: Thu, 18 Aug 2016 07:49:50 +000