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 Publishing Corporation [439 journals]
- Non-Hermitian Dirac Hamiltonian in Three-Dimensional Gravity and
Abstract: The Dirac Hamiltonian in the -dimensional curved space-time has been studied with a metric for an expanding de Sitter space-time which is two spheres. The spectrum and the exact solutions of the time dependent non-Hermitian and angle dependent Hamiltonians are obtained in terms of the Jacobi and Romanovski polynomials. Hermitian equivalent of the Hamiltonian obtained from the Dirac equation is discussed in the frame of pseudo-Hermiticity. Furthermore, pseudosupersymmetric quantum mechanical techniques are expanded to a curved Dirac Hamiltonian and a partner curved Dirac Hamiltonian is generated. Using -pseudo-Hermiticity, the intertwining operator connecting the non-Hermitian Hamiltonians to the Hermitian counterparts is found. We have obtained a new metric tensor related to the new Hamiltonian.
PubDate: Thu, 19 Nov 2015 16:00:09 +000
- Critical Combinations of Higher-Order Terms in Einstein-Maxwell Theory and
Abstract: We discuss the role of a particular combination of higher derivative terms in higher dimensional theories, particularly in the background of spontaneous compactification. Two classes of theories are proposed in this paper. The first model as a generalization of the critical gravity with the Maxwell field could have a de Sitter solution. We consider the Lanczos-Lovelock term and Horndeski term as well as the higher-order Maxwell term for the second model, which contains a possible longer expansion time for the inflationary phase. It is interesting that both models can be regarded as the generalization of the Randjbar-Daemi, Salam and Strathdee (RSS) model and give the well behavior for inflation stage under the specific assumptions.
PubDate: Wed, 18 Nov 2015 09:04:26 +000
- Complex-Mass Definition and the Structure of Unstable Particle’s
Abstract: The propagators of unstable particles are considered in framework of the convolution representation. Spectral function is found for a special case when the propagator of scalar unstable particle has Breit-Wigner form. The expressions for the dressed propagators of unstable vector and spinor fields are derived in an analytical way for this case. We obtain the propagators in modified Breit-Wigner forms which correspond to the complex-mass definition.
PubDate: Wed, 18 Nov 2015 08:13:05 +000
- Fate of Electromagnetic Field on the Cracking of PSR J1614-2230 in
Abstract: We study the cracking of compact object PSR J1614-2230 in quadratic regime with electromagnetic field. For this purpose, we develop a general formalism to determine the cracking of charged compact objects. We apply local density perturbations to hydrostatic equilibrium equation as well as physical variables involved in the model. We plot the force distribution function against radius of the star with different parametric values of model both with and without charge. It is found that PSR J1614-2230 remains stable (no cracking) corresponding to different values of parameters when charge is zero, while it exhibits cracking (unstable) when charge is introduced. We conclude that stability region increases as amount of charge increases.
PubDate: Tue, 17 Nov 2015 08:24:13 +000
- Maximally Localized States and Quantum Corrections of Black Hole
Thermodynamics in the Framework of a New Generalized Uncertainty Principle
Abstract: As a generalized uncertainty principle (GUP) leads to the effects of the minimal length of the order of the Planck scale and UV/IR mixing, some significant physical concepts and quantities are modified or corrected correspondingly. On the one hand, we derive the maximally localized states—the physical states displaying the minimal length uncertainty associated with a new GUP proposed in our previous work. On the other hand, in the framework of this new GUP we calculate quantum corrections to the thermodynamic quantities of the Schwardzschild black hole, such as the Hawking temperature, the entropy, and the heat capacity, and give a remnant mass of the black hole at the end of the evaporation process. Moreover, we compare our results with that obtained in the frameworks of several other GUPs. In particular, we observe a significant difference between the situations with and without the consideration of the UV/IR mixing effect in the quantum corrections to the evaporation rate and the decay time. That is, the decay time can greatly be prolonged in the former case, which implies that the quantum correction from the UV/IR mixing effect may give rise to a radical rather than a tiny influence to the Hawking radiation.
PubDate: Tue, 17 Nov 2015 07:54:30 +000
- Augmented Superfield Approach to Nilpotent Symmetries of the Modified
Version of 2D Proca Theory
Abstract: We derive the complete set of off-shell nilpotent and absolutely anticommuting Becchi-Rouet-Stora-Tyutin (BRST), anti-BRST, and (anti-)co-BRST symmetry transformations for all the fields of the modified version of two -dimensional (2D) Proca theory by exploiting the “augmented” superfield formalism where the (dual-)horizontality conditions and (dual-)gauge invariant restrictions are exploited together. We capture the (anti-)BRST and (anti-)co-BRST invariance of the Lagrangian density in the language of superfield approach. We also express the nilpotency and absolute anticommutativity of the (anti-)BRST and (anti-)co-BRST charges within the framework of augmented superfield formalism. This exercise leads to some novel observations which have, hitherto, not been pointed out in the literature within the framework of superfield approach to BRST formalism. For the sake of completeness, we also mention, very briefly, a unique bosonic symmetry, the ghost-scale symmetry, and discrete symmetries of the theory and show that the algebra of conserved charges provides a physical realization of the Hodge algebra (satisfied by the de Rham cohomological operators of differential geometry).
PubDate: Wed, 11 Nov 2015 06:38:20 +000
- Probing Mixing of Photons and Axion-Like Particles by Geometric Phase
Abstract: We find that a geometric phase characterizes the phenomenon of mixing of photons with axion-like particles (ALPs). The laboratory observation of such a phase may provide a novel tool able to detect such a mixing phenomenon. We show that the geometric phase is dependent on the axion-like particle mass and coupling constant. We discuss an interferometric experiment able to detect the geometric phase associated with the ALPs-photon mixing.
PubDate: Tue, 10 Nov 2015 11:44:49 +000
- Holographic Polytropic Gravity Models
Abstract: The present paper reports a study on the cosmological consequences arising from reconstructing gravity through new holographic polytropic dark energy. We assume two approaches, namely, a particular form of Hubble parameter and a solution for . We obtain the deceleration parameter and effective equation of state, as well as torsion equation of state parameters from total density and pressure in both cases. It is interesting to mention here that the deceleration and torsion equation of state represent transition from deceleration to acceleration phase. We study the statefinder parameters under both approaches which result in the fact that statefinder trajectories are found to attain ΛCDM point. The comparison with observational data represents consistent results. Also, we discuss the stability of reconstructed models through squared speed of sound which represents stability in late times.
PubDate: Wed, 04 Nov 2015 11:27:00 +000
- Study of Nonleptonic and Weak Decays
Abstract: Motivated by the powerful capability of measurement for the hadron decays at LHC and SuperKEKB/Belle-II, the nonleptonic , , , , and decays are studied. With the amplitudes calculated with factorization approach and the form factors evaluated with the BSW model, branching fractions and polarization fractions are firstly presented. Numerically, the CKM-favored and decays have branching fractions ~10−8, which should be sought for with priority and firstly observed by LHC and Belle-II. The and decays are dominated by the longitudinal polarization states, while the parallel polarization fractions of decays are comparable with the longitudinal ones; numerically, + 95% and . Some comparisons between and their corresponding decays are performed, and the relation is found. With the implication of flavor symmetry, the ratios and are discussed and suggested to be verified experimentally.
PubDate: Tue, 03 Nov 2015 13:34:49 +000
- Klein-Gordon Equation with Superintegrable Systems: Kepler-Coulomb,
Harmonic Oscillator, and Hyperboloid
Abstract: We study the two-dimensional Klein-Gordon equation with spin symmetry in the presence of the superintegrable potentials. On Euclidean space, the group generators of the Schrödinger-like equation with the Kepler-Coulomb potential are represented. In addition, by Levi-Civita transformation, the Schrödinger-like equation with harmonic oscillator which is dual to the Kepler-Coulomb potential and the group generators of associated system are studied. Also, we construct the quadratic algebra of the hyperboloid superintegrable system. Then, we obtain the corresponding Casimir operators and the structure functions and the relativistic energy spectra of the corresponding quasi-Hamiltonians by using the quadratic algebra approach.
PubDate: Thu, 29 Oct 2015 14:06:33 +000
- Phase Transitions of the BTZ Black Hole in New Massive Gravity
Abstract: We investigate thermodynamics of the BTZ black hole in new massive gravity explicitly. For with being the mass parameter of fourth-order terms and AdS curvature radius, the Hawking-Page phase transition occurs between the BTZ black hole and AdS (thermal) soliton. For , however, this transition unlikely occurs but a phase transition between the BTZ black hole and the massless BTZ black hole is possible to occur. We may call the latter the inverse Hawking-Page phase transition and this transition is favored in the new massive gravity.
PubDate: Sun, 25 Oct 2015 12:25:19 +000
- From the Schwarzschild Anti-de Sitter Black Hole to the Conformal Field
Abstract: The emergence of the quantum gravitational effects in a very high energy regime necessitates some corrections to the thermodynamics of black holes. In this letter, we investigate a possible modification to the thermodynamics of Schwarzschild anti-de Sitter (SAdS) black holes due to rainbow gravity model. Using the correspondence between a ()-dimensional SAdS black hole and a conformal filed theory in -dimensional spacetime, one may find the corrections to the Cardy-Verlinde formula from the modified thermodynamics of the black hole. Furthermore, we show that the corrected Cardy-Verlinde formula can also be derived by redefining the Virasoro operator and the central charge.
PubDate: Sun, 25 Oct 2015 07:00:38 +000
- On the Thermodynamic Properties of the Spinless Duffin-Kemmer-Petiau
Oscillator in Noncommutative Plane
Abstract: The Duffin-Kemmer-Petiau oscillator for spin 0 particle in noncommutative plane is analyzed and the energy eigenvalue of the system is obtained by employing the functional analysis method. Furthermore, the thermodynamic properties of the noncommutative DKP oscillator are investigated via numerical method and the influence of noncommutative space on thermodynamic functions is also discussed. We show that the energy spectrum and corresponding thermodynamic functions of the considered physical systems depend explicitly on the noncommutative parameter which characterizes the noncommutativity of the space.
PubDate: Thu, 22 Oct 2015 11:40:45 +000
- An Inconsistency in the Spectrum of Bosonic Open 2-Brane
Abstract: We show that the spectrum of a bosonic open 2-brane does not contain any massless states to take the role of gravitons. Moreover, the spectrum of this open 2-brane only contains half integer mass squared values.
PubDate: Wed, 21 Oct 2015 08:36:44 +000
- Exploring New Models in All Detail with SARAH
Abstract: I give an overview about the features the Mathematica package SARAH provides to study new models. In general, SARAH can handle a wide range of models beyond the MSSM coming with additional chiral superfields, extra gauge groups, or distinctive features like Dirac gaugino masses. All of these models can be implemented in a compact form in SARAH and are easy to use: SARAH extracts all analytical properties of the given model like two-loop renormalization group equations, tadpole equations, mass matrices, and vertices. Also one- and two-loop corrections to tadpoles and self-energies can be obtained. For numerical calculations SARAH can be interfaced with other tools to get the mass spectrum, to check flavour or dark matter constraints, and to test the vacuum stability or to perform collider studies. In particular, the interface to SPheno allows a precise prediction of the Higgs mass in a given model comparable to MSSM precision by incorporating the important two-loop corrections. I show in great detail with the example of the B-L-SSM how SARAH together with SPheno, HiggsBounds/HiggsSignals, FlavorKit, Vevacious, CalcHep, MicrOmegas, WHIZARD, and MadGraph can be used to study all phenomenological aspects of a model.
PubDate: Thu, 15 Oct 2015 09:32:50 +000
- Mesons in Asymmetric Hot and Dense Hadronic Matter
Abstract: The in-medium properties of mesons are investigated within the framework of an effective hadronic model, which is a generalization of a chiral model, to , in order to study the interactions of the charmed hadrons. In the present work, the mesons are observed to experience net attractive interactions in a dense hadronic medium, hence reducing the masses of the and mesons from the vacuum values. While this conclusion holds in both nuclear and hyperonic media, the magnitude of the mass drop is observed to intensify with the inclusion of strangeness in the medium. Additionally, in hyperonic medium, the mass degeneracy of the mesons is observed to be broken, due to opposite signs of the Weinberg-Tomozawa interaction term in the Lagrangian density. Along with the magnitude of the mass drops, the mass splitting between and mesons is also observed to grow with an increase in baryonic density and strangeness content of the medium. However, all medium effects analyzed are found to be weakly dependent on isospin asymmetry and temperature. We discuss the possible implications emanating from this analysis, which are all expected to make a significant difference to observables in heavy ion collision experiments, especially the upcoming Compressed Baryonic Matter (CBM) experiment at the future Facility for Antiproton and Ion Research (FAIR), GSI, where matter at high baryonic densities is planned to be produced.
PubDate: Thu, 15 Oct 2015 09:06:29 +000
- Magnetic Moments of 70-Plet Baryons in Quark Model and QCD Sum Rules
Abstract: Magnetic moments of the positive parity 70-plet baryons are estimated in the framework of the nonrelativistic quark model and QCD sum rules method. It is found that the magnetic moments of the 70-plet baryons can be expressed in terms of the F and D couplings and exhibit unitary symmetry. The QCD sum rules for the magnetic moments of the 70-plet octet baryons are formulated. A comparison of our results on magnetic moments of 56-plet and 70-plet baryons predicted from QCD sum rules is presented.
PubDate: Mon, 12 Oct 2015 11:46:35 +000
- Physics at a Fixed-Target Experiment Using the LHC Beams
PubDate: Wed, 07 Oct 2015 08:11:31 +000
- Next-to-Leading Order Differential Cross Sections for , , and Production
in Proton-Proton Collisions at a Fixed-Target Experiment Using the LHC
Abstract: Using nonrelativistic QCD (NRQCD) factorization, we calculate the yields for , , and hadroproduction at GeV and 115 GeV including the next-to-leading order QCD corrections. Both these center-of-mass energies correspond to those obtained with 7 TeV and 2.76 TeV nucleon beam impinging a fixed target. We study the cross section integrated in as a function of the (center-of-mass) rapidity as well as the differential cross section in the central rapidity region. Using different NLO fit results of the NRQCD long-distance matrix elements, we evaluate a theoretical uncertainty which is certainly much larger than the projected experimental uncertainties with the expected 20 fb−1 to be collected per year with AFTER@LHC for collision at the center of mass energy GeV.
PubDate: Mon, 05 Oct 2015 08:17:47 +000
- Supersymmetry beyond the NMSSM
PubDate: Mon, 05 Oct 2015 07:55:03 +000
- Vacuum Condensates as a Mechanism of Spontaneous Supersymmetry Breaking
Abstract: A possible mechanism for the spontaneous breaking of SUSY, based on the presence of vacuum condensates, is reviewed. Such a mechanism could occur in many physical examples, at both the fundamental and emergent levels, and would be formally analogous to spontaneous SUSY breaking at finite temperature in the TFD formalism, in which case it can be applied as well. A possible experimental setup for detecting such a breaking through measurement of the Anandan-Aharonov invariants associated with vacuum condensates in an optical lattice model is proposed.
PubDate: Sun, 04 Oct 2015 14:05:30 +000
- The Gluon Sivers Distribution: Status and Future Prospects
Abstract: We review what is currently known about the gluon Sivers distribution and what are the opportunities to learn more about it. Because single transverse spin asymmetries in provide only indirect information about the gluon Sivers function through the relation with the quark-gluon and tri-gluon Qiu-Sterman functions, current data from hadronic collisions at RHIC have not yet been translated into a solid constraint on the gluon Sivers function. SIDIS data, including the COMPASS deuteron data, allow for a gluon Sivers contribution of natural size expected from large arguments, which is times the nonsinglet quark Sivers contribution. Several very promising processes to measure the gluon Sivers effect directly have been suggested, which besides RHIC investigations, would strongly favor experiments at AFTER@LHC and a possible future Electron-Ion Collider. Due to the inherent process dependence of TMDs, the gluon Sivers TMD probed in the various processes are different linear combinations of two universal gluon Sivers functions that have different behavior under charge conjugation and that therefore satisfy different theoretical constraints. For this reason both hadronic and DIS type of collisions are essential in the study of the role of gluons in transversely polarized protons.
PubDate: Sun, 04 Oct 2015 12:58:11 +000
- Studies of Backward Particle Production with a Fixed-Target Experiment
Using the LHC Beams
Abstract: The foreseen capability to cover the far backward region at a Fixed-Target Experiment using the LHC beams allows one to explore the dynamics of the target fragmentation in hadronic collisions. In this report we briefly outline the required theoretical framework and discuss a number of studies of forward and backward particle production. By comparing this knowledge with the one accumulated in Deep Inelastic Scattering on target fragmentation, the basic concept of QCD factorisation could be investigated in detail.
PubDate: Sun, 04 Oct 2015 12:56:02 +000
- Antishadowing Effect on Charmonium Production at a Fixed-Target Experiment
Using LHC Beams
Abstract: We investigate charmonium production in Pb + Pb collisions at LHC beam energy TeV at fixed-target experiment ( = 72 GeV). In the frame of a transport approach including cold and hot nuclear matter effects on charmonium evolution, we focus on the antishadowing effect on the nuclear modification factors and for the yield and transverse momentum. The yield is more suppressed at less forward rapidity () than that at very forward rapidity () due to the shadowing and antishadowing in different rapidity bins.
PubDate: Sun, 04 Oct 2015 12:16:15 +000
- Bremsstrahlung from Relativistic Heavy Ions in a Fixed Target Experiment
at the LHC
Abstract: We calculate the emission of bremsstrahlung from lead and argon ions in ultraperipheral collisions in a fixed target experiment (AFTER) that uses the LHC beams. With nuclear charges of Ze equal to 82e and 18e, respectively, these ions are accelerated to energies of 7 Tev × Z. The bremsstrahlung peaks around ≈100 GeV and the spectrum exposes the nuclear structure of the incoming ion. The peak structure is significantly different from the flat power spectrum pertaining to a point charge. Photons are predominantly emitted within an angle of 1/γ to the direction of ion propagation. Our calculations are based on the Weizsäcker-Williams method of virtual quanta with application of existing experimental data on photonuclear interactions.
PubDate: Sun, 04 Oct 2015 11:35:27 +000
- Quarkonium Production and Proposal of the New Experiments on Fixed Target
at the LHC
Abstract: The brief review of the experimental data on quarkonium productions measured at the CERN SPS, at the Brookhaven Collider RHIC, and at the LHC is presented. The dissociation of quarkonium resonances produced in heavy ion collisions was suggested as a possible signal of the Quark-Gluon Plasma formation. At the CERN SPS, the anomalous suppression of the production was observed in central Pb-Pb collisions by the NA50 collaboration. However, the effects of suppression on cold nuclear matter, feed-down production from higher charmonium states, and regeneration processes should be taken into account. If proton and ion beams at the LHC will be used with fixed targets, the energy interval between the SPS energy and the nominal RHIC energy (200 GeV) could be investigated. The high statistics data on quarkonium productions at these energies will give the possibility of clarifying the mechanism of charmonium productions to investigate the importance of the recombination process, since the probability of recombination decreases with decreasing the energy of collisions.
PubDate: Sun, 04 Oct 2015 11:09:14 +000
- Quarkonium Suppression from Coherent Energy Loss in Fixed-Target
Experiments Using LHC Beams
Abstract: Quarkonium production in proton-nucleus collisions is a powerful tool to disentangle cold nuclear matter effects. A model based on coherent energy loss is able to explain the available quarkonium suppression data in a broad range of rapidities, from fixed-target to collider energies, suggesting coherent energy loss in cold nuclear matter to be the dominant effect in quarkonium suppression in p-A collisions. This could be further tested in a high-energy fixed-target experiment using a proton or nucleus beam. The nuclear modification factors of and as a function of rapidity are computed in p-A collisions at GeV, and in p-Pb and Pb-Pb collisions at GeV. These center-of-mass energies correspond to the collision on fixed-target nuclei of 7 TeV protons and 2.76 TeV (per nucleon) lead nuclei available at the LHC.
PubDate: Sun, 04 Oct 2015 09:42:48 +000
- Transverse Single-Spin Asymmetries in Proton-Proton Collisions at the
AFTER@LHC Experiment in a TMD Factorisation Scheme
Abstract: The inclusive large- production of a single pion, jet or direct photon, and Drell-Yan processes, are considered for proton-proton collisions in the kinematical range expected for the fixed-target experiment AFTER, proposed at LHC. For all these processes, predictions are given for the transverse single-spin asymmetry, , computed according to a Generalised Parton Model previously discussed in the literature and based on TMD factorisation. Comparisons with the results of a collinear twist-3 approach, recently presented, are made and discussed.
PubDate: Sun, 04 Oct 2015 09:41:32 +000
- Transverse Single-Spin Asymmetries in Proton-Proton Collisions at the
Abstract: We present results for transverse single-spin asymmetries in proton-proton collisions at kinematics relevant for AFTER, a proposed fixed-target experiment at the Large Hadron Collider. These include predictions for pion, jet, and direct photon production from analytical formulas already available in the literature. We also discuss specific measurements that will benefit from the higher luminosity of AFTER, which could help resolve an almost 40-year puzzle of what causes transverse single-spin asymmetries in proton-proton collisions.
PubDate: Sun, 04 Oct 2015 09:39:11 +000
- A Chargeless Complex Vector Matter Field in Supersymmetric Scenario
Abstract: We construct and study a formulation of a chargeless complex vector matter field in a supersymmetric framework. To this aim we combine two nochiral scalar superfields in order to take the vector component field to build the chargeless complex vector superpartner where the respective field strength transforms into matter fields by a global gauge symmetry. For the aim of dealing with consistent terms without breaking the global symmetry we imposes a choice to the complex combination revealing a kind of symmetry between the choices and eliminates the extra degrees of freedom which is consistent with the supersymmetry. As the usual case the mass supersymmetric sector contributes as a complement to dynamics of the model. We obtain the equations of motion of the Proca’s type field for the chiral spinor fields and for the scalar field on the mass-shell which show the same mass as expected. This work establishes the first steps to extend the analysis of charged massive vector field in a supersymmetric scenario.
PubDate: Sun, 04 Oct 2015 09:39:11 +000