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 [407 journals]
- Spontaneous Symmetry Breaking in 5D Conformally Invariant Gravity
Abstract: We explore the possibility of the spontaneous symmetry breaking in 5D conformally invariant gravity, whose action consists of a scalar field nonminimally coupled to the curvature with its potential. Performing dimensional reduction via ADM decomposition, we find that the model allows an exact solution giving rise to the 4D Minkowski vacuum. Exploiting the conformal invariance with Gaussian warp factor, we show that it also admits a solution which implements the spontaneous breaking of conformal symmetry. We investigate its stability by performing the tensor perturbation and find the resulting system is described by the conformal quantum mechanics. Possible applications to the spontaneous symmetry breaking of time-translational symmetry along the dynamical fifth direction and the brane-world scenario are discussed.
PubDate: Wed, 27 Jul 2016 07:44:34 +000
- Analysis of the Intermediate-State Contributions to Neutrinoless Double
Abstract: A comprehensive analysis of the structure of the nuclear matrix elements (NMEs) of neutrinoless double beta-minus () decays to the ground and first excited states is performed in terms of the contributing multipole states in the intermediate nuclei of transitions. We concentrate on the transitions mediated by the light (l-NMEs) Majorana neutrinos. As nuclear model we use the proton-neutron quasiparticle random-phase approximation (pnQRPA) with a realistic two-nucleon interaction based on the Bonn one-boson-exchange matrix. In the computations we include the appropriate short-range correlations, nucleon form factors, and higher-order nucleonic weak currents and restore the isospin symmetry by the isoscalar-isovector decomposition of the particle-particle proton-neutron interaction parameter .
PubDate: Tue, 26 Jul 2016 07:04:01 +000
- Calculating Masses of Pentaquarks Composed of Baryons and Mesons
Abstract: We consider an exotic baryon (pentaquark) as a bound state of two-body systems composed of a baryon (nucleon) and a meson. We used a baryon-meson picture to reduce a complicated five-body problem to simple two-body problems. The homogeneous Lippmann-Schwinger integral equation is solved in configuration space by using one-pion exchange potential. We calculate the masses of pentaquarks and .
PubDate: Mon, 25 Jul 2016 11:29:16 +000
- Thermodynamic Product Relations for Generalized Regular Black Hole
Abstract: We derive thermodynamic product relations for four-parametric regular black hole (BH) solutions of the Einstein equations coupled with a nonlinear electrodynamics source. The four parameters can be described by the mass (), charge (), dipole moment (), and quadrupole moment (), respectively. We study its complete thermodynamics. We compute different thermodynamic products, that is, area product, BH temperature product, specific heat product, and Komar energy product, respectively. Furthermore, we show some complicated function of horizon areas that is indeed mass-independent and could turn out to be universal.
PubDate: Mon, 25 Jul 2016 06:32:01 +000
- High Order QCD Predictions for Inclusive Production of Bosons in
Collisions at TeV
Abstract: Predictions of fiducial cross sections, differential cross sections, and lepton charge asymmetry are presented for the production of bosons with leptonic decay up to next-to-next-to-leading order (NNLO) in perturbative QCD. Differential cross sections of bosons and boson lepton charge asymmetry are computed as a function of lepton pseudorapidity for a defined fiducial region in collisions at TeV. Numerical results of fiducial cross section predictions are presented with the latest modern PDF models at next-to-leading order (NLO) and NNLO. It is found that the CT14 and NNPDF 3.0 predictions with NNLO QCD corrections are about 4% higher than the NLO CT14 and NNPDF 3.0 predictions while MMHT 2014 predictions with NLO QCD corrections are smaller than its NNLO QCD predictions by approximately 6%. In addition, the NNLO QCD corrections reduce the scale variation uncertainty on the cross section by a factor of 3.5. The prediction of central values and considered uncertainties are obtained using FEWZ 3.1 program.
PubDate: Tue, 19 Jul 2016 12:12:03 +000
- Solution of Deformed Einstein Equations and Quantum Black Holes
Abstract: Recently, one- and two-parameter deformed Einstein equations have been studied for extremal quantum black holes which have been proposed to obey deformed statistics by Strominger. In this study, we give a deeper insight into the deformed Einstein equations and consider the solutions of these equations for the extremal quantum black holes. We then represent the implications of the solutions, such that the deformation parameters lead the charged black holes to have a smaller mass than the usual Reissner-Nordström black holes. This reduction in mass of a usual black hole can be considered as a transition from classical to quantum black hole regime.
PubDate: Mon, 18 Jul 2016 16:32:02 +000
- On the UV Dimensions of Loop Quantum Gravity
Abstract: Planck-scale dynamical dimensional reduction is attracting more and more interest in the quantum-gravity literature since it seems to be a model independent effect. However, different studies base their results on different concepts of space-time dimensionality. Most of them rely on the spectral dimension; others refer to the Hausdorff dimension; and, very recently, the thermal dimension has also been introduced. We here show that all these distinct definitions of dimension give the same outcome in the case of the effective regime of Loop Quantum Gravity (LQG). This is achieved by deriving a modified dispersion relation from the hypersurface-deformation algebra with quantum corrections. Moreover, we also observe that the number of UV dimensions can be used to constrain the ambiguities in the choice of these LQG-based modifications of the Dirac space-time algebra. In this regard, introducing the polymerization of connections, that is, , we find that the leading quantum correction gives . This result may indicate that the running to the expected value of two dimensions is ongoing, but it has not been completed yet. Finding at ultrashort distances would require going beyond the effective approach we here present.
PubDate: Mon, 18 Jul 2016 14:24:40 +000
- Charged Massive Particle’s Tunneling from Charged Nonrotating
Abstract: In the tunneling framework of Hawking radiation, charged massive particle’s tunneling in charged nonrotating TeV-scale black hole is investigated. To this end, we consider natural cutoffs as a minimal length, a minimal momentum, and a maximal momentum through a generalized uncertainty principle. We focus on the role played by these natural cutoffs on the luminosity of charged nonrotating microblack hole by taking into account the full implications of energy and charge conservation as well as the backscattered radiation.
PubDate: Sun, 17 Jul 2016 14:19:38 +000
- Production of in Radiative Decays
Abstract: We investigate the production of in the process , where is assumed to be the counterpart of in the bottomonium sector as molecular state. We use the effective Lagrangian based on the heavy quark symmetry to explore the rescattering mechanism and calculate their production ratios. Our results have shown that the production ratios for are orders of with reasonable cutoff parameter range . The sizeable production ratios may be accessible at the future experiments like forthcoming BelleII, which will provide important clues to the inner structures of the exotic state .
PubDate: Thu, 14 Jul 2016 16:00:57 +000
- Lepton Pair Čerenkov Radiation Emitted by Tachyonic Neutrinos:
Lorentz-Covariant Approach and IceCube Data
Abstract: Current experiments do not exclude the possibility that one or more neutrinos are very slightly superluminal or that they have a very small tachyonic mass. Important bounds on the size of a hypothetical tachyonic neutrino mass term are set by lepton pair Čerenkov radiation (LPCR), that is, by the decay channel , which proceeds via a virtual boson. Here, we use a Lorentz-invariant dispersion relation which leads to very tight constraints on the tachyonic mass of neutrinos; we also calculate decay and energy loss rates. A possible cutoff seen in the IceCube neutrino spectrum for PeV, due to the potential onset of LPCR, is discussed.
PubDate: Thu, 14 Jul 2016 09:57:30 +000
- Lorentz Invariance Violation and Modified Hawking Fermions Tunneling
Abstract: Recently the modified Dirac equation with Lorentz invariance violation has been proposed, which would be helpful to resolve some issues in quantum gravity theory and high energy physics. In this paper, the modified Dirac equation has been generalized in curved spacetime, and then fermion tunneling of black holes is researched under this correctional Dirac field theory. We also use semiclassical approximation method to get correctional Hamilton-Jacobi equation, so that the correctional Hawking temperature and correctional black hole’s entropy are derived.
PubDate: Tue, 12 Jul 2016 12:16:28 +000
- Do Small-Mass Neutrinos Participate in Gauge Transformations'
Abstract: Neutrino oscillation experiments presently suggest that neutrinos have a small but finite mass. If neutrinos have mass, there should be a Lorentz frame in which they can be brought to rest. This paper discusses how Wigner’s little groups can be used to distinguish between massive and massless particles. We derive a representation of the group which separates out the two sets of spinors: one set is gauge dependent and the other set is gauge invariant and represents polarized neutrinos. We show that a similar calculation can be done for the Dirac equation. In the large-momentum/zero-mass limit, the Dirac spinors can be separated into large and small components. The large components are gauge invariant, while the small components are not. These small components represent spin- non-zero-mass particles. If we renormalize the large components, these gauge invariant spinors represent the polarization of neutrinos. Massive neutrinos cannot be invariant under gauge transformations.
PubDate: Tue, 12 Jul 2016 07:34:32 +000
- Self-Regular Black Holes Quantized by means of an Analogue to Hydrogen
Abstract: We suggest a quantum black hole model that is based on an analogue to hydrogen atoms. A self-regular Schwarzschild-AdS black hole is investigated, where the mass density of the extreme black hole is given by the probability density of the ground state of hydrogen atoms and the mass densities of nonextreme black holes are given by the probability densities of excited states with no angular momenta. Such an analogue is inclined to adopt quantization of black hole horizons. In this way, the total mass of black holes is quantized. Furthermore, the quantum hoop conjecture and the Correspondence Principle are discussed.
PubDate: Mon, 04 Jul 2016 11:26:01 +000
- On the Study of Oscillons in Scalar Field Theories: A New Approach
Abstract: We study configurations in one-dimensional scalar field theory, which are time-dependent, localized in space, and extremely long-lived, called oscillons. How the action of changing the minimum value of the field configuration representing the oscillon affects its behavior is investigated. We find that one of the consequences of this procedure is the appearance of a pair of oscillon-like structures presenting different amplitudes and frequencies of oscillation. We also compare our analytical results to numerical ones, showing excellent agreement.
PubDate: Thu, 30 Jun 2016 15:21:52 +000
- Effects of the FCNC Couplings in Production of New Heavy Quarks within
Models at the LHC
Abstract: We study the flavor changing neutral current couplings of new heavy quarks through the models at the LHC. We calculate the cross sections for the signal and the corresponding standard model background processes. Considering the present limits on the mass of new heavy quarks and the boson, we performed an analysis to investigate the parameter space (mixing and mass) through different models. For FCNC mixing parameter and the mass GeV and new heavy quark mass GeV at the LHC with TeV, we find the cross section for single production of new heavy quarks associated with top quarks as fb, fb, fb, and fb within the , , , and models, respectively. It is shown that the sensitivity would benefit from the flavor tagging.
PubDate: Thu, 30 Jun 2016 11:13:03 +000
- On a Neutral Particle with a Magnetic Quadrupole Moment in a Uniform
Effective Magnetic Field
Abstract: Quantum effects on a Landau-type system associated with a moving atom with a magnetic quadrupole moment subject to confining potentials are analysed. It is shown that the spectrum of energy of the Landau-type system can be modified, where the degeneracy of the energy levels can be broken. In three particular cases, it is shown that the analogue of the cyclotron frequency is modified, and the possible values of this angular frequency of the system are determined by the quantum numbers associated with the radial modes and the angular momentum and by the parameters associated with confining potentials in order that bound states solutions can be achieved.
PubDate: Tue, 28 Jun 2016 12:20:43 +000
- 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