Advances in High Energy Physics
[SJR: 1.334] [H-I: 12] [14 followers] Follow
Open Access journal
ISSN (Print) 1687-7357 - ISSN (Online) 1687-7365
Published by Hindawi [406 journals]
- Comment on “Does the Equivalence between Gravitational Mass and
Energy Survive for a Composite Quantum Body?”
Abstract: Lebed has given an argument that when a hydrogen atom is transported slowly to a different gravitational potential, it has a certain probability of emitting a photon. He proposes a space-based experiment to detect this effect. I show here that his arguments also imply the existence of nuclear excitations, as well as an effect due to the earth’s motion in the sun’s potential. This is not consistent with previous results from underground radiation detectors. It is also in conflict with astronomical observations.
PubDate: Tue, 28 Jun 2016 06:31:17 +000
- Decays with Perturbative QCD Approach
Abstract: Besides the traditional strong and electromagnetic decay modes, meson can also decay through the weak interactions within the standard model of elementary particle. With anticipation of copious data samples at the running LHC and coming SuperKEKB experiments, the two-body nonleptonic bottom-changing decays () are investigated with perturbative QCD approach firstly. The absolute branching ratios for and decays are estimated to reach up to about and , respectively, which might possibly be measured by the future experiments.
PubDate: Tue, 21 Jun 2016 08:55:15 +000
- Supervariable Approach to the Nilpotent Symmetries for a Toy Model of the
Abstract: We exploit the standard techniques of the supervariable approach to derive the nilpotent Becchi-Rouet-Stora-Tyutin (BRST) and anti-BRST symmetry transformations for a toy model of the Hodge theory (i.e., a rigid rotor) and provide the geometrical meaning and interpretation to them. Furthermore, we also derive the nilpotent (anti-)co-BRST symmetry transformations for this theory within the framework of the above supervariable approach. We capture the (anti-)BRST and (anti-)co-BRST invariance of the Lagrangian of our present theory within the framework of augmented supervariable formalism. We also express the (anti-)BRST and (anti-)co-BRST charges in terms of the supervariables (obtained after the application of the (dual-)horizontality conditions and (anti-)BRST and (anti-)co-BRST invariant restrictions) to provide the geometrical interpretations for their nilpotency and anticommutativity properties. The application of the dual-horizontality condition and ensuing proper (i.e., nilpotent and absolutely anticommuting) fermionic (anti-)co-BRST symmetries are completely novel results in our present investigation.
PubDate: Mon, 20 Jun 2016 12:59:49 +000
- Charmless Decays in the QCD Factorization Approach
Abstract: The charmless decays (where and denote the light pseudoscalar and vector mesons, resp.) can occur only via the weak annihilation diagrams within the Standard Model. In this paper, we study these kinds of decays in the framework of QCD factorization, by adopting two different schemes: scheme I is similar to the method usually adopted in the QCD factorization approach, while scheme II is based on the infrared behavior of gluon propagator and running coupling. For comparison, in our calculation, we adopt three kinds of wave functions for meson. The branching ratios based on the two schemes are given. It is found that (a) the predicted branching ratios in scheme I are, however, quite small and almost impossible to be measured at the LHCb experiment and (b) in scheme II, by assigning a dynamical gluon mass to the gluon propagator, we can avoid enhancements of the contribution from soft endpoint region. The strength of annihilation contributions predicted in scheme II is enhanced compared to that obtained in scheme I.
PubDate: Wed, 15 Jun 2016 10:51:00 +000
- On a Search for Hidden Photon CDM by a Multicathode Counter
Abstract: We report a new technique of a multicathode counter (MCC) developed to search for hidden photon (HP) cold dark matter (CDM) with a mass from 5 to 500 eV. The method is suggested in the assumption that HP-photon mixing causes emission of single electrons from a metal cathode if the mass of hidden photon is greater than a work function of the metal . The measured effect from HP should be dependent on and on the structure of electronic shells of the metal used as a cathode. Potentially this can be used for a verification of the results obtained. Some preliminary results for the upper limit for mixing parameter have been obtained for HP with a mass from 5 eV to 10 keV as a pure illustration of the potential of this technique. The efforts are continued to refine the procedure of data treatment and to improve the work of MCC. A new detector with a more developed design is under construction.
PubDate: Wed, 15 Jun 2016 06:46:29 +000
- Quantum Mechanics on a Curved Snyder Space
Abstract: We study the representations of the three-dimensional Euclidean Snyder-de Sitter algebra. This algebra generates the symmetries of a model admitting two fundamental scales (Planck mass and cosmological constant) and is invariant under the Born reciprocity for exchange of positions and momenta. Its representations can be obtained starting from those of the Snyder algebra and exploiting the geometrical properties of the phase space that can be identified with a Grassmannian manifold. Both the position and momentum operators turn out to have a discrete spectrum.
PubDate: Mon, 13 Jun 2016 08:02:57 +000
- Surface and Buildup Region Dose Measurements with Markus Parallel-Plate
Ionization Chamber, GafChromic EBT3 Film, and MOSFET Detector for
High-Energy Photon Beams
Abstract: The aim of the study was to investigate surface and buildup region doses for 6 MV and 15 MV photon beams using a Markus parallel-plate ionization chamber, GafChromic EBT3 film, and MOSFET detector for different field sizes and beam angles. The measurements were made in a water equivalent solid phantom at the surface and in the buildup region of the 6 MV and 15 MV photon beams at 100 cm source-detector distance for 5 × 5, 10 × 10, and 20 × 20 cm2 field sizes and 0°, 30°, 60°, and 80° beam angles. The surface doses using 6 MV photon beams for 10 × 10 cm2 field size were found to be 20.3%, 18.8%, and 25.5% for Markus chamber, EBT3 film, and MOSFET detector, respectively. The surface doses using 15 MV photon beams for 10 × 10 cm2 field size were found to be 14.9%, 13.4%, and 16.4% for Markus chamber, EBT3 film, and MOSFET detector, respectively. The surface dose increased with field size for all dosimeters. As the angle of the incident radiation beam became more oblique, the surface dose increased. The effective measurement depths of dosimeters vary; thus, the results of the measurements could be different. This issue can lead to mistakes at surface and buildup dosimetry and must be taken into account.
PubDate: Sun, 12 Jun 2016 09:09:16 +000
- The Effect of de-Sitter Like Background on Increasing the Zero Point
Budget of Dark Energy
Abstract: During this work, using subtraction renormalization mechanism, zero point quantum fluctuations for bosonic scalar fields in a de-Sitter like background are investigated. By virtue of the observed value for spectral index, , for massive scalar field the best value for the first slow roll parameter, , is achieved. In addition, the energy density of vacuum quantum fluctuations for massless scalar field is obtained. The effects of these fluctuations on other components of the universe are studied. By solving the conservation equation, for some different examples, the energy density for different components of the universe is obtained. In the case which all components of the universe are in an interaction, the different dissipation functions, , are considered. The time evolution of shows that has the best agreement in comparison to observational data including CMB, BAO, and SNeIa data set.
PubDate: Wed, 08 Jun 2016 08:49:37 +000
- Time-Dependent Toroidal Compactification Proposals and the Bianchi Type I
Model: Classical and Quantum Solutions
Abstract: We construct an effective four-dimensional model by compactifying a ten-dimensional theory of gravity coupled with a real scalar dilaton field on a time-dependent torus. This approach is applied to anisotropic cosmological Bianchi type I model for which we study the classical coupling of the anisotropic scale factors with the two real scalar moduli produced by the compactification process. Under this approach, we present an isotropization mechanism for the Bianchi I cosmological model through the analysis of the ratio between the anisotropic parameters and the volume of the Universe which in general keeps constant or runs into zero for late times. We also find that the presence of extra dimensions in this model can accelerate the isotropization process depending on the momenta moduli values. Finally, we present some solutions to the corresponding Wheeler-DeWitt (WDW) equation in the context of standard quantum cosmology.
PubDate: Tue, 07 Jun 2016 12:21:03 +000
- Thermodynamics of Charged Rotating Dilaton Black Branes Coupled to
Logarithmic Nonlinear Electrodynamics
Abstract: We construct a new class of charged rotating black brane solutions in the presence of logarithmic nonlinear electrodynamics with complete set of the rotation parameters in arbitrary dimensions. The topology of the horizon of these rotating black branes is flat, while due to the presence of the dilaton field the asymptotic behavior of them is neither flat nor (anti-)de Sitter [(A)dS]. We investigate the physical properties of the solutions. The mass and angular momentum of the spacetime are obtained by using the counterterm method inspired by AdS/CFT correspondence. We derive temperature, electric potential, and entropy associated with the horizon and check the validity of the first law of thermodynamics on the black brane horizon. We study thermal stability of the solutions in both canonical and grand-canonical ensemble and disclose the effects of the rotation parameter, nonlinearity of electrodynamics, and dilaton field on the thermal stability conditions. We find the solutions are thermally stable for , while for the solutions may encounter an unstable phase, where is dilaton-electromagnetic coupling constant.
PubDate: Mon, 06 Jun 2016 11:13:17 +000
- A Gauged Open 2-Brane String in the -Brane Background
Abstract: We make a gauge theory from the Open -brane system and map it into the Open 2-Brane one. Due to the presence of second-class constraints in this model, we encounter some problems during the procedure of quantization. In this regard, considering boundary conditions as Dirac conditions, one can drive the constrained structure of the model at first. Then, with the help of BFT formalism of constraint systems, the Open 2-Brane model is embedded into an extended phase space. For this purpose, we introduce some tensor fields to convert ungauged theory into the gauged one. This is the novel part of our research, while mostly scalar and vector fields are used to convert second-class constraints into first ones.
PubDate: Mon, 06 Jun 2016 07:42:49 +000
- Combined Effect of NSI and SFP on Solar Electron Neutrino Oscillation
Abstract: The combined effect of spin-flavor precession (SFP) and the nonstandard neutrino interaction (NSI) on the survival probability of solar electron neutrinos (assumed to be Dirac particles) is examined for various values of , , and . It is found that the neutrino survival probability curves affected by SFP and NSI effects individually for some values of the parameters (, , and ) get close to the standard MSW curve when both effects are combined. Therefore, the combined effect of SFP and NSI needs to be taken into account when the solar electron neutrino data obtained by low energy solar neutrino experiments is investigated.
PubDate: Sun, 05 Jun 2016 13:42:46 +000
- A Universal Description of Pseudorapidity Distributions in Both
Nucleus-Nucleus and p-p Collisions at Currently Available Energies
Abstract: Investigations have shown that the collective motion appears not only in nucleus-nucleus but also in p-p collisions. The best tool for depicting such collective motion is relativistic hydrodynamics. In this paper, the collective motion is assumed to obey the hydrodynamic model which integrates the features of Landau and Hwa-Bjorken theory and is one of a very few analytically solvable models. The fluid is then supposed to freeze out into charged particles from a space-like hypersurface with a fixed time of . The investigations of present paper show that this part of charged particles together with leading particles, which, by conventional definition, carry on the quantum numbers of colliding nucleons and take away the most part of incident energy, can give a proper universal description to the pseudorapidity distributions of charged particles measured in both nucleus-nucleus and p-p collisions at currently available energies.
PubDate: Mon, 30 May 2016 11:26:06 +000
- Tryon’s Conjecture and Energy and Momentum of Bianchi Type
Abstract: The energy and momentum of some diagonal anisotropic Bianchi type Universes are obtained using different energy-momentum complexes in the framework of General Relativity. The Møller energy is found to be zero for all the Universes considered in the present work. In all other prescriptions, the energy and momentum vanish when the sum of the metric parameters and vanishes. This result obviously raises a question: why this specific choice' We have explored Tryon’s conjecture that the Universe must have a zero net value for all conserved quantities to get some ideas on this issue.
PubDate: Sun, 29 May 2016 09:02:11 +000
- Superspace Unitary Operator in Superfield Approach to Non-Abelian Gauge
Theory with Dirac Fields
Abstract: Within the framework of augmented version of the superfield approach to Becchi-Rouet-Stora-Tyutin (BRST) formalism, we derive the superspace unitary operator (and its Hermitian conjugate) in the context of four (3 + 1)-dimensional (4D) interacting non-Abelian 1-form gauge theory with Dirac fields. The ordinary 4D non-Abelian theory, defined on the flat 4D Minkowski spacetime manifold, is generalized onto a (4, 2)-dimensional supermanifold which is parameterized by the spacetime bosonic coordinates (with ) and a pair of Grassmannian variables () which satisfy the standard relationships: and . Various consequences of the application of the above superspace (SUSP) unitary operator (and its Hermitian conjugate) are discussed. In particular, we obtain the results of the application of horizontality condition (HC) and gauge-invariant restriction (GIR) in the language of the above SUSP operators. One of the novel results of our present investigation is the derivation of explicit expressions for the SUSP unitary operator (and its Hermitian conjugate) without imposing any Hermitian conjugation condition from outside on the parameters and (super)fields of the supersymmetric version of our 4D interacting non-Abelian 1-form theory with Dirac fields.
PubDate: Thu, 26 May 2016 17:15:04 +000
- Chiral Perturbation Theory for Three-Flavour Lattice QCD with Isospin
Abstract: An important tool for the analysis of results of numerical simulations of lattice QCD is chiral perturbation theory. In the Wilson chiral perturbation theory the effects of the finite lattice spacing are taken into account. In recent years the effects of isospin splitting on the masses of hadrons have been investigated in the Monte Carlo simulations. Correspondingly, in this paper we derive the expansions of the masses of the pseudoscalar mesons in chiral perturbation theory at next-to-leading order for twisted mass lattice QCD with three light quark flavours, taking the mass difference between the up- and downquarks into account. The results include terms up to orders in the quark masses, in the mass splitting between up- and downquarks, and in the lattice spacing, respectively.
PubDate: Wed, 18 May 2016 11:50:13 +000
- The Phase Transition of Higher Dimensional Charged Black Holes
Abstract: We have studied phase transitions of higher dimensional charge black hole with spherical symmetry. We calculated the local energy and local temperature and find that these state parameters satisfy the first law of thermodynamics. We analyze the critical behavior of black hole thermodynamic system by taking state parameters of black hole thermodynamic system, in accordance with considering the state parameters of van der Waals system, respectively. We obtain the critical point of black hole thermodynamic system and find that the critical point is independent of the dual independent variables we selected. This result for asymptotically flat space is consistent with that for AdS spacetime and is intrinsic property of black hole thermodynamic system.
PubDate: Mon, 16 May 2016 11:29:50 +000
- Searching for Minimum in Dependence of Squared Speed-of-Sound on Collision
Abstract: Experimental results of the rapidity distributions of negatively charged pions produced in proton-proton (-) and beryllium-beryllium (Be-Be) collisions at different beam momentums, measured by the NA61/SHINE Collaboration at the super proton synchrotron (SPS), are described by a revised (three-source) Landau hydrodynamic model. The squared speed-of-sound parameter is then extracted from the width of rapidity distribution. There is a local minimum (knee point) which indicates a softest point in the equation of state (EoS) appearing at about GeV/ (or 8.8 GeV) in excitation function (the dependence of on incident beam momentum (or center-of-mass energy)). This knee point should be related to the searching for the onset of quark deconfinement and the critical point of quark-gluon plasma (QGP) phase transition.
PubDate: Thu, 12 May 2016 14:07:05 +000
- Aspects of Screening and Confinement in a Topologically Massive
Abstract: By using the gauge-invariant but path-dependent variables formalism, we consider a recently proposed topologically massive Chern-Simons-Higgs theory in dimensions. In particular, we inspect the impact of a Chern-Simons mixing term between two Abelian gauge fields on physical observables. We pursue our investigation by analyzing the model in two different situations. In the first case, where we integrate the massive excitation and consider an effective model for the massless field, we show that the interaction energy contains a linear term leading to the confinement of static charge probes along with a screening contribution. In the second situation, where the massless field can be exactly integrated with its constraint duly taken into account, the interesting feature is that the resulting effective model describes a purely screening phase, without any trace of a confining regime.
PubDate: Thu, 12 May 2016 10:33:36 +000
- Comparative Multifractal Detrended Fluctuation Analysis of Heavy Ion
Interactions at a Few GeV to a Few Hundred GeV
Abstract: We have studied the multifractality of pion emission process in 16O-AgBr interactions at 2.1 AGeV and 60 AGeV, 12C-AgBr and 24Mg-AgBr interactions at 4.5 AGeV, and 32S-AgBr interactions at 200 AGeV using Multifractal Detrended Fluctuation Analysis (MFDFA) method which is capable of extracting the actual multifractal property filtering out the average trend of fluctuation. The analysis reveals that the pseudorapidity distribution of the shower particles is multifractal in nature for all the interactions; that is, pion production mechanism has inbuilt multiscale self-similarity property. We have employed MFDFA method for randomly generated events for 32S-AgBr interactions at 200 AGeV. Comparison of expt. results with those obtained from randomly generated data set reveals that the source of multifractality in our data is the presence of long range correlation. Comparing the results obtained from different interactions, it may be concluded that strength of multifractality decreases with projectile mass for the same projectile energy and for a particular projectile it increases with energy. The values of ordinary Hurst exponent suggest that there is long range correlation present in our data for all the interactions.
PubDate: Tue, 10 May 2016 16:22:49 +000
- Thermodynamical Study of FRW Universe in Quasi-Topological Theory
Abstract: By applying the unified first law of thermodynamics on the apparent horizon of FRW universe, we get the entropy relation for the apparent horizon in quasi-topological gravity theory. Throughout the paper, the results of considering the Hayward-Kodama and Cai-Kim temperatures are also addressed. Our study shows that whenever there is no energy exchange between the various parts of cosmos, we can get an expression for the apparent horizon entropy in quasi-topological gravity, which is in agreement with other attempts that followed different approaches. The effects of a mutual interaction between the various parts of cosmos on the apparent horizon entropy as well as the validity of second law of thermodynamics in quasi-topological gravity are perused.
PubDate: Tue, 10 May 2016 06:46:55 +000
- Magnetic Hexadecapole Transitions and Neutrino-Nuclear Responses in
Abstract: Neutrino-nuclear responses in the form of squares of nuclear matrix elements, NMEs, are crucial for studies of neutrino-induced processes in nuclei. In this work we investigate magnetic hexadecapole (M4) NMEs in medium-heavy nuclei. The experimentally derived NMEs, (M4), deduced from observed M4 transition half-lives are compared with the single-quasiparticle (QP) NMEs, (M4), and the microscopic quasiparticle-phonon model (MQPM) NMEs (M4). The experimentally derived M4 NMEs are found to be reduced by a coefficient with respect to (M4) and by with respect to (M4). The M4 NMEs are reduced a little by the quasiparticle-phonon correlations of the MQPM wave functions but mainly by other nucleonic and nonnucleonic correlations which are not explicitly included in the MQPM. The found reduction rates are of the same order of magnitude as those for magnetic quadrupole transitions and Gamow-Teller (GT) and spin-dipole (SD) transitions. The impacts of the found reduction coefficients on the magnitudes of the NMEs involved in astroneutrino interactions and neutrinoless double beta decays are discussed.
PubDate: Mon, 09 May 2016 10:57:05 +000
- Corrections to the Jet Quenching Parameter
Abstract: A calculation of corrections to the jet quenching parameter from AdS/CFT correspondence is presented. It is shown that these corrections will increase or decrease the jet quenching parameter depending on the coefficients of the high curvature terms.
PubDate: Sun, 08 May 2016 12:36:25 +000
- Geometric Algebra Techniques in Flux Compactifications
Abstract: We study “constrained generalized Killing (s)pinors,” which characterize supersymmetric flux compactifications of supergravity theories. Using geometric algebra techniques, we give conceptually clear and computationally effective methods for translating supersymmetry conditions into differential and algebraic constraints on collections of differential forms. In particular, we give a synthetic description of Fierz identities, which are an important ingredient of such problems. As an application, we show how our approach can be used to efficiently treat compactification of M-theory on eight manifolds and prove that we recover results previously obtained in the literature.
PubDate: Wed, 27 Apr 2016 12:45:48 +000
- On Dynamical Net-Charge Fluctuations within a Hadron Resonance Gas
Abstract: The dynamical net-charge fluctuations () in different particle ratios , , and are calculated from the hadron resonance gas (HRG) model and compared with STAR central Au+Au collisions at GeV and NA49 central Pb+Pb collisions at GeV. The three charged particle ratios (, and ) are determined as total and average of opposite and average of the same charges. We find an excellent agreement between the HRG calculations and the experimental measurements, especially from STAR beam energy scan (BES) program, while the strange particles in the NA49 experiment at lower Super Proton Synchrotron (SPS) energies are not reproduced by the HRG approach. We conclude that the utilized HRG version seems to take into consideration various types of correlations including strong interactions through the heavy resonances and their decays especially at BES energies.
PubDate: Wed, 27 Apr 2016 12:21:39 +000
- Study of Time Evolution for Approximation of Two-Body Spinless Salpeter
Equation in Presence of Time-Dependent Interaction
Abstract: We approximate the two-body spinless Salpeter equation with the one which is valid in heavy quarks limit. We consider the resulting semirelativistic equation in a time-dependent formulation. We use the Lewis-Riesenfeld dynamical invariant method and series solution to obtain the solutions of the differential equation. We have also done some calculations in order to derive the time evolution operator for the considered problem.
PubDate: Wed, 27 Apr 2016 09:24:47 +000
- An Effective Method to Accurately Calculate the Phase Space Factors for
Abstract: Accurate calculations of the electron phase space factors are necessary for reliable predictions of double-beta decay rates and for the analysis of the associated electron angular and energy distributions. We present an effective method to calculate these phase space factors that takes into account the distorted Coulomb field of the daughter nucleus, yet it allows one to easily calculate the phase space factors with good accuracy relative to the most exact methods available in the recent literature.
PubDate: Wed, 27 Apr 2016 09:17:23 +000
- Study of Strange Charmed Meson Family Using HQET
Abstract: Recently LHCb predicted spin 1 and spin 3 states and which are studied through their strong decays and are assigned to fit the and states in the charm spectroscopy. In this paper, using the heavy quark effective theory, we state that assigning as the mixing of states is rather a better justification to its observed experimental values than a pure state. We study its decay modes variation with hadronic coupling constant and the mixing angle . We appoint spin 3 state as the missing state and also study its decay channel behavior with coupling constant . To appreciate the above results, we check the variation of decay modes for their spin partners states, that is, and , with their masses and strong coupling constant, that is, and . Our calculation using HQET approach gives mixing angle of the state for to lie in the range ( radians radians). Our calculation for coupling constant values gives to lie within value range of and to be 0.40. We expect from experiments to observe this mixing angle to verify our results.
PubDate: Tue, 26 Apr 2016 12:34:33 +000
- Investigation of Pionic Contribution in the Lepton and Antilepton
Production Cross Section in p-Cu and p-Pt Collision
Abstract: For detailed explanation of the experimental results of lepton production cross section in hadronic collisions such as nucleon-nucleon or nucleon-nuclei, it is of great importance to use quarks and sea quarks distribution function inside free and bound nucleons. In this paper, the role of pion cloud inside the nucleus in the structure function of Cu and Pt nuclei and the EMC ratio of these nuclei were investigated by using harmonic oscillator model. Then, in the framework of the Drell-Yan process and conventional nuclear theory, GRV’s quarks distribution functions and pionic quarks distribution functions were used to calculate lepton and antilepton production cross section in p-Cu and p-Pt scattering. From the results and based on the mentioned model, by considering pionic contribution, the theoretical results are improved.
PubDate: Sun, 24 Apr 2016 13:54:29 +000
- Testing an Inflation Model with Nonminimal Derivative Coupling in the
Light of Planck 2015 Data
Abstract: We study the dynamics of a generalized inflationary model in which both the scalar field and its derivatives are coupled with the gravity. We consider a general form of the nonminimal derivative coupling in order to have a complete treatment of the model. By expanding the action up to the second order in perturbation, we study the spectrum of the primordial modes of the perturbations. Also, by expanding the action up to the third order and considering the three-point correlation functions, the amplitude of the non-Gaussianity of the primordial perturbations is studied in both equilateral and orthogonal configurations. Finally, by adopting some sort of potentials, we compare the model in hand with the Planck 2015 released observational data and obtain some constraints on the model’s parameters space. As an important result, we show that the nonminimal couplings help to make models of chaotic inflation that would otherwise be in tension with Planck data, in better agreement with the data. This model is consistent with observation at weak coupling limit.
PubDate: Thu, 21 Apr 2016 09:24:27 +000