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 [366 journals] [SJR: 1.297] [H-I: 7]
- Extracting the QCD Cutoff Parameter Using the Bernstein Polynomials and
the Truncated Moments
Abstract: Since there are not experimental data over the whole range of -Bjorken variable, that is, , we are inevitable in practice to do the integration for Mellin moments over the available range of experimental data. Among the methods of analysing DIS data, there are the methods based on application of Mellin moments. We use the truncated Mellin moments rather than the usual moments to analyse the EMC collaboration data for muon-nucleon and WA25 data for neutrino-deuterium DIS scattering. How to connect the truncated Mellin moments to usual ones is discussed. Following that we combine the truncated Mellin moments with the Bernstein polynomials. As a result, Bernstein averages which are related to different orders of the truncated Mellin moment are obtained. These averaged quantities can be considered as the constructed experimental data. By accessing the sufficient experimental data we can do the fitting more precisely. We do the fitting at leading order and next-to-leading order approximations to extract the QCD cutoff parameter. The results are in good agreement with what is being expected.
PubDate: Tue, 11 Nov 2014 12:16:24 +000
- Field Equations and Radial Solutions in a Noncommutative Spherically
Abstract: We study a noncommutative theory of gravity in the framework of torsional spacetime. This theory is based on a Lagrangian obtained by applying the technique of dimensional reduction of noncommutative gauge theory and that the yielded diffeomorphism invariant field theory can be made equivalent to a teleparallel formulation of gravity. Field equations are derived in the framework of teleparallel gravity through Weitzenbock geometry. We solve these field equations by considering a mass that is distributed spherically symmetrically in a stationary static spacetime in order to obtain a noncommutative line element. This new line element interestingly reaffirms the coherent state theory for a noncommutative Schwarzschild black hole. For the first time, we derive the Newtonian gravitational force equation in the commutative relativity framework, and this result could provide the possibility to investigate examples in various topics in quantum and ordinary theories of gravity.
PubDate: Tue, 11 Nov 2014 10:23:12 +000
- Probing the Top Quark Flavour-Changing Neutral Current at a Future
Abstract: We present a study to examine the sensitivity of a future collider to the anomalous top flavour-changing neutral current (FCNC) to the gluon. To separate signal from background a multivariate analysis is performed on top quark pair and background events, where one top quark is considered to follow the dominant standard model (SM) decay, , and the other top decays through FCNC, , where is a - or a -quark. The analysis of fully hadronic FCNC decay of the pair is also presented. The 95% confidence level limits on the top quark anomalous couplings are obtained for different values of the center-of-mass energies and integrated luminosities.
PubDate: Mon, 03 Nov 2014 07:11:07 +000
- Correspondence of Modified Gravity with Scalar Field Models
Abstract: This paper is devoted to study the scalar field dark energy models by taking its different aspects in the framework of gravity. We consider flat FRW universe to construct the equation of state parameter governed by gravity. The stability of the model is discussed with the help of squared speed of sound parameter. It is found that models show quintessence behavior of the universe in stable as well as unstable modes. We also develop the correspondence of model with some scalar field dark energy models like quintessence, tachyonic field, k-essence, dilaton, hessence, and DBI-essence. The nature of scalar fields and corresponding scalar potentials is being analyzed in gravity graphically which show consistency with the present day observations about accelerated phenomenon.
PubDate: Sun, 02 Nov 2014 08:01:34 +000
- Fractional Quantum Field Theory: From Lattice to Continuum
Abstract: An approach to formulate fractional field theories on unbounded lattice space-time is suggested. A fractional-order analog of the lattice quantum field theories is considered. Lattice analogs of the fractional-order 4-dimensional differential operators are proposed. We prove that continuum limit of the suggested lattice field theory gives a fractional field theory for the continuum 4-dimensional space-time. The fractional field equations, which are derived from equations for lattice space-time with long-range properties of power-law type, contain the Riesz type derivatives on noninteger orders with respect to space-time coordinates.
PubDate: Thu, 30 Oct 2014 10:20:33 +000
- Investigation of the Rare Exclusive Decays in the Framework of the QCD Sum
Abstract: Exclusive decay is studied in the framework of the three-point QCD sum rules approach. The two gluon condensate contributions to the correlation function are calculated and the form factors of this transition are found. The decay width and total branching ratio for this decay are also calculated.
PubDate: Mon, 27 Oct 2014 08:49:23 +000
- Development of a Liquid Scintillator Using Water for a Next Generation
Abstract: A feasibility study on a new type of liquid scintillator based on water has been performed. Mainly due to the differences in polarities between water and oil, organic solvents are not mixed in water. In order to make a liquid scintillator based on water, a surfactant that contains hydrophilic and hydrophobic groups is used. The surfactant keeps water and organic solvents apart in solution. Good physical and optical parameters and long-term stability are required to use liquid scintillator based on water in massive detector for the next generation neutrino experiments. In this paper, we report the characteristics and the possibility of liquid scintillators using water with various new surfactants.
PubDate: Mon, 27 Oct 2014 00:00:00 +000
- Spherically Symmetric Solution in (1+4)-Dimensional Gravity Theories
Abstract: A nondiagonal spherically symmetric tetrad field, involving four unknown functions of radial coordinate plus an angle , which is a generalization of the azimuthal angle , is applied to the field equations of (1+4)-dimensional gravity theory. A special vacuum solution with one constant of integration is derived. The physical meaning of this constant is shown to be related to the gravitational mass of the system and the associated metric represents Schwarzschild in (1+4)-dimension. The scalar torsion related to this solution vanishes. We put the derived solution in a matrix form and rewrite it as a product of three matrices: the first represents a rotation while the second represents an inertia and the third matrix is the diagonal square root of Schwarzschild spacetime in (1+4)-dimension.
PubDate: Thu, 23 Oct 2014 13:06:24 +000
- Identification of Parton Pairs in a Dijet Event and Investigation of Its
Effects on Dijet Resonance Search
Abstract: Being able to distinguish parton pair type in a dijet event could significantly improve the search for new particles that are predicted by the theories beyond the Standard Model at the Large Hadron Collider. To explore whether parton pair types manifesting themselves as a dijet event could be distinguished on an event-by-event basis, I performed a simulation based study considering observable jet variables. I found that using a multivariate approach can filter out about 80% of the other parton pairs while keeping more than half of the quark-quark or gluon-gluon parton pairs in an inclusive QCD dijet distribution. The effects of event-by-event parton pair tagging for dijet resonance searches were also investigated and I found that improvement on signal significance after applying parton pair tagging can reach up to 4 times for gluon-gluon resonances.
PubDate: Tue, 21 Oct 2014 00:00:00 +000
- Langevin Diffusion in Holographic Backgrounds with Hyperscaling Violation
Abstract: We consider a relativistic heavy quark which moves in the quark-gluon plasmas. By using the holographic methods, we analyze the Langevin diffusion process of this relativistic heavy quark. This heavy quark is described by a trailing string attached to a flavor brane and moving at constant velocity. The fluctuations of this string are related to the thermal correlators and the correlation functions are precisely the kinds of objects that we compute in the gravity dual picture. We obtain the action of the trailing string in hyperscaling violation backgrounds and we then find the equations of motion. These equations lead us to constructing the Langevin correlator which helps us to obtain the Langevin constants. Using the Langevin correlators we derive the spectral densities and simple analytic expressions in the small- and large-frequency limits. We examine our works for planar and -charged black holes with hyperscaling violation and find new constraints on in the presence of velocity .
PubDate: Mon, 20 Oct 2014 09:09:02 +000
- Rotating Dilaton Black Strings Coupled to Exponential Nonlinear
Abstract: We construct a new class of charged rotating black string solutions coupled to dilaton and exponential nonlinear electrodynamic fields with cylindrical or toroidal horizons in the presence of a Liouville-type potential for the dilaton field. Due to the presence of the dilaton field, the asymptotic behaviors of these solutions are neither flat nor (A)dS. We analyze the physical properties of the solutions in detail. We compute the conserved and thermodynamic quantities of the solutions and verify the first law of thermodynamics on the black string horizon. When the nonlinear parameter goes to infinity, our results reduce to those of black string solutions in Einstein-Maxwell-dilaton gravity.
PubDate: Mon, 20 Oct 2014 00:00:00 +000
- Effects of Noncommutativity on the Black Hole Entropy
Abstract: The BTZ black hole geometry is probed with a noncommutative scalar field which obeys the κ-Minkowski algebra. The entropy of the BTZ black hole is calculated using the brick wall method. The contribution of the noncommutativity to the black hole entropy is explicitly evaluated up to the first order in the deformation parameter. We also argue that such a correction to the black hole entropy can be interpreted as arising from the renormalization of the Newton’s constant due to the effects of the noncommutativity.
PubDate: Thu, 16 Oct 2014 08:42:46 +000
- Spinless Particles in Exponentially Varying Electric and Magnetic Fields
Abstract: We investigate the motion of the charged spin-0 particles subjected to the space-dependent electric and magnetic fields. By selecting the external fields oriented parallel and orthogonal to each other, exact solutions of the motion are obtained for the nonrelativistic and the relativistic cases. The quantized energy spectrum is determined by using the solutions obtained for the motion of the particles and dependence of the energy on the strengths of the electric and magnetic fields is discussed. We compared the energy spectrum of the nonrelativistic and the relativistic particles by using the numerical results obtained for the first few quantum levels.
PubDate: Wed, 15 Oct 2014 08:26:25 +000
- Classical Bianchi Type I Cosmology in K-Essence Theory
Abstract: We use one of the simplest forms of the K-essence theory and we apply it to the classical anisotropic Bianchi type I cosmological model, with a barotropic perfect fluid () modeling the usual matter content and with cosmological constant . Classical exact solutions for any and are found in closed form, whereas solutions for are found for particular values in the barotropic parameter. We present the possible isotropization of the cosmological model Bianchi I using the ratio between the anisotropic parameters and the volume of the universe. We also include a qualitative analysis of the analog of the Friedmann equation.
PubDate: Tue, 14 Oct 2014 08:20:47 +000
- Probing Features of the Lee-Wick Quantum Electrodynamics
Abstract: We discuss some aspects concerning the electromagnetic sector of the abelian Lee-Wick (LW) quantum electrodynamics (QED). Using the Dirac’s theory of constrained systems, the higher-order canonical quantization of the LW electromagnetism is performed. A quantum bound on the LW heavy mass is also estimated using the best known measurement of the anomalous magnetic moment of the electron. Finally, it is shown that magnetic monopoles can coexist peacefully in the LW scenario.
PubDate: Mon, 13 Oct 2014 11:43:11 +000
- Semileptonic Transition of Tensor to Meson
Abstract: Taking into account the two-gluon condensate corrections, the transition form factors of the semileptonic decay channel are calculated via three-point QCD sum rules. These form factors are used to estimate the decay width of the transition under consideration in both electron and muon channels. The obtained results can be used both in direct search for such decay channels at charm factories and in analysis of the Bc meson decay at LHC.
PubDate: Mon, 13 Oct 2014 07:15:18 +000
- Reconstructions of Einstein-Aether Gravity from Ordinary and
Entropy-Corrected Versions of Holographic and New Agegraphic Dark Energy
Abstract: Here we briefly discuss the Einstein-Aether gravity theory by modification of Einstein-Hilbert action. We find the modified Friedmann equations and then from the equations we find the effective density and pressure for Einstein-Aether gravity sector. These can be treated as if dark energy provided some restrictions on the free function , where is proportional to . Assuming two types of the power law solutions of the scale factor, we have reconstructed the unknown function from HDE and NADE and their entropy-corrected versions (ECHDE and ECNADE). We also obtain the EoS parameter for Einstein-Aether gravity dark energy. For HDE and NADE, we have shown that the type I scale factor generates the quintessence scenario only and type II scale factor generates phantom scenario. But for ECHDE and ECNADE, both types of scale factors can accommodate the transition from quintessence to phantom stages; that is, phantom crossing is possible for entropy-corrected terms of HDE and NADE models. Finally, we show that the models are classically unstable.
PubDate: Sun, 12 Oct 2014 12:50:10 +000
- Regge Poles in Neutron Scattering by a Cylinder
Abstract: We establish asymptotic expressions for the positions of Regge poles for cold neutron scattering on mesoscopic cylinder mirror as well as for the -matrix residuals. We outline the correspondence between Regge poles and near-surface quasi-stationary neutron states. Such states are of practical importance for studying subtle effects of neutron-surface interaction.
PubDate: Tue, 16 Sep 2014 09:23:35 +000
- FRW Cosmology with the Extended Chaplygin Gas
Abstract: We propose extended Chaplygin gas equation of state for which it recovers barotropic fluid with quadratic equation of state. We use numerical method to investigate the behavior of some cosmological parameters such as scale factor, Hubble expansion parameter, energy density, and deceleration parameter. We also discuss the resulting effective equation of state parameter. Using density perturbations we investigate the stability of the theory.
PubDate: Mon, 15 Sep 2014 08:47:22 +000
- A Field Theory with Curvature and Anticurvature
Abstract: The present work is an attempt to construct a unified field theory in a space with curvature and anticurvature, the PAP-space. The theory is derived from an action principle and a Lagrangian density using a symmetric linear parameterized connection. Three different methods are used to explore physical contents of the theory obtained. Poisson’s equations for both material and charge distributions are obtained, as special cases, from the field equations of the theory. The theory is a pure geometric one in the sense that material distribution, charge distribution, gravitational and electromagnetic potentials, and other physical quantities are defined in terms of pure geometric objects of the structure used. In the case of pure gravity in free space, the spherical symmetric solution of the field equations gives the Schwarzschild exterior field. The weak equivalence principle is respected only in the case of pure gravity in free space; otherwise it is violated.
PubDate: Sun, 14 Sep 2014 08:05:35 +000
- Study of Baryon Spectroscopy Using a New Potential Form
Abstract: In the present work, the nonrelativistic quark model is applied to study baryon systems, where the constituent quarks are bound by a suitable hyper central potential. We proposed a new phenomenological form of the interaction potential, digamma-type potential. Using the Jacobi coordinates, the three-body wave equation is solved numerically to calculate the resonance states of the , and baryon systems. The present model contains only two adjustable parameters in addition to the quark masses. Our theoretical calculations are compared to the available experimental data and Cornell potential results. The description of the spectrum shows that the ground states of the considered light and strange baryon spectra are in general well reproduced.
PubDate: Wed, 10 Sep 2014 13:18:01 +000
- Method of Studying Decays with One Missing Particle
Abstract: A new technique is discussed that can be applied to baryon decays where decays with one missing particle can be discerned from background and their branching fractions determined, along with other properties of the decays. Applications include measurements of the CKM elements and and detection of any exotic objects coupling to decays, such as the inflaton. Potential use of and to investigate decays is also commented upon.
PubDate: Wed, 10 Sep 2014 09:36:03 +000
- Precision Measurement of the Position-Space Wave Functions of
Gravitationally Bound Ultracold Neutrons
Abstract: Gravity is the most familiar force at our natural length scale. However, it is still exotic from the view point of particle physics. The first experimental study of quantum effects under gravity was performed using a cold neutron beam in 1975. Following this, an investigation of gravitationally bound quantum states using ultracold neutrons was started in 2002. This quantum bound system is now well understood, and one can use it as a tunable tool to probe gravity. In this paper, we review a recent measurement of position-space wave functions of such gravitationally bound states and discuss issues related to this analysis, such as neutron loss models in a thin neutron guide, the formulation of phase space quantum mechanics, and UCN position sensitive detectors. The quantum modulation of neutron bound states measured in this experiment shows good agreement with the prediction from quantum mechanics.
PubDate: Wed, 10 Sep 2014 07:20:56 +000
- Schwarzschild-de Sitter and Anti-de Sitter Thin-Shell Wormholes and Their
Abstract: This paper is devoted to construct Schwarzschild-de Sitter and anti-de Sitter thin-shell wormholes by employing Visser’s cut and paste technique. The Darmois-Israel formalism is adopted to formulate the surface stresses of the shell. We analyze null and weak energy conditions as well as attractive and repulsive characteristics of thin-shell wormholes. We also explore stable and unstable solutions against linear perturbations by taking two different Chaplygin gas models for exotic matter. It is concluded that the stress-energy tensor components violate the null and weak energy conditions indicating the existence of exotic matter at the wormhole throat. Finally, we find unstable and stable configurations for the constructed thin-shell wormholes.
PubDate: Tue, 09 Sep 2014 12:17:18 +000
- Error-Disturbance Uncertainty Relations in Neutron-Spin Measurements
Abstract: In his seminal paper, which was published in 1927, Heisenberg originally introduced a relation between the precision of a measurement and the disturbance it induces onto another measurement. Here, we report a neutron-optical experiment that records the error of a spin-component measurement as well as the disturbance caused on a measurement of another spin-component to test error-disturbance uncertainty relations (EDRs). We demonstrate that Heisenberg’s original EDR is violated and the Ozawa and Branciard EDRs are valid in a wide range of experimental parameters.
PubDate: Mon, 08 Sep 2014 05:44:43 +000
- The Scattering and Bound States of the Schrödinger Particle in
Generalized Asymmetric Manning-Rosen Type Potential
Abstract: We solve exactly one-dimensional Schrödinger equation for the generalized asymmetric Manning-Rosen (GAMAR) type potential containing the different types of physical potential that have many application fields in the nonrelativistic quantum mechanics and obtain the solutions in terms of the Gauss hypergeometric functions. Then we determine the solutions for scattering and bound states. By using these states we calculate the reflection and transmission coefficients for scattering states and achieve a correlation that gives the energy eigenvalues for the bound states. In addition to these, we show how the transmission and reflection coefficients depend on the parameters which describe shape of the GAMAR type potential and compare our results with the results obtained in earlier studies.
PubDate: Sun, 07 Sep 2014 07:07:51 +000
- Importance of Nonperturbative QCD Parameters for Bottom Mesons
Abstract: The importance of nonperturbative quantum chromodynamics (QCD) parameters is discussed in context to the predicting power for bottom meson masses and isospin splitting. In the framework of heavy quark effective theory, the work presented here focuses on the different allowed values of the two nonperturbative QCD parameters used in heavy quark effective theory formula, and using the best fitted parameter, masses of the excited bottom meson states in doublet in strange and nonstrange sectors are calculated here. The calculated masses are found to be matching well with experiments and other phenomenological models. The mass splitting and hyperfine splitting have also been analyzed for both strange and nonstrange heavy mesons with respect to spin and flavor symmetries.
PubDate: Wed, 03 Sep 2014 11:49:54 +000
- Pion Spectra in Collisions as a Function of and Event Multiplicity
Abstract: We study the charged pion transverse momentum spectra in collisions as a function of collision energy and event multiplicity using Tsallis distribution. This study gives an insight of the pion production process in collisions. The study covers pion spectra measured in collisions at SPS energies (6.27–17.27 GeV), RHIC energies (62.4 GeV and 200 GeV), and LHC energies (900 GeV, 2.76 TeV, and 7 TeV). The Tsallis parameters have been obtained and parameterized as a function of . The study suggests that as we move to higher energy more and more hard processes contribute to the spectra. We also study the charged pion spectra for different event multiplicities in collisions for LHC energies using Tsallis distribution. The variation of the Tsallis parameters as a function of event multiplicity has been obtained and their behavior is found to be independent of collision energy.
PubDate: Tue, 02 Sep 2014 12:49:52 +000
- Holographic Renormalization in Dense Medium
Abstract: The holographic renormalization of a charged black brane with or without a dilaton field, whose dual field theory describes a dense medium at finite temperature, is investigated in this paper. In a dense medium, two different thermodynamic descriptions are possible due to an additional conserved charge. These two different thermodynamic ensembles are classified by the asymptotic boundary condition of the bulk gauge field. It is also shown that in the holographic renormalization regularity of all bulk fields can reproduce consistent thermodynamic quantities and that the Bekenstein-Hawking entropy is nothing but the renormalized thermal entropy of the dual field theory. Furthermore, we find that the Reissner-Nordström AdS black brane is dual to a theory with conformal matter as expected, whereas a charged black brane with a nontrivial dilaton profile is mapped to a theory with nonconformal matter although its leading asymptotic geometry still remains as AdS space.
PubDate: Tue, 02 Sep 2014 12:30:30 +000
- 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