Advances in High Energy Physics
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The latest articles from Hindawi Publishing Corporation
© 2015 , Hindawi Publishing Corporation . All rights reserved.

Balance Function in HighEnergy Collisions
Thu, 23 Apr 2015 10:44:37 +0000
http://www.hindawi.com/journals/ahep/2015/186812/
Aspects and implications of the balance functions (BF) in highenergy physics are reviewed. The
various calculations and measurements depending on different quantities, for example, system size, collisions
centrality, and beam energy, are discussed. First, the different definitions including advantages and
even shortcomings are highlighted. It is found that BF, which are mainly presented in terms of
relative rapidity, and relative azimuthal and invariant relative momentum, are sensitive to the interaction
centrality but not to the beam energy and can be used in estimating the hadronization time and the
hadronquark phase transition. Furthermore, the quark chemistry can be determined. The chemical
evolution of the newstateofmatter, the quarkgluon plasma, and its temporalspatial evolution,
femtoscopy of twoparticle correlations, are accessible. The production time of positivenegative
pair of charges can be determined from the widths of BF. Due to the reduction in the diffusion
time, narrowed widths refer to delayed hadronization. It is concluded that BF are powerful tools
characterizing hadronquark phase transition and estimating some essential properties.
A. Tawfik and Asmaa G. Shalaby
Copyright © 2015 A. Tawfik and Asmaa G. Shalaby. All rights reserved.

Quantum Probes of Timelike Naked Singularities in Dimensional PowerLaw Spacetimes
Sun, 19 Apr 2015 17:00:27 +0000
http://www.hindawi.com/journals/ahep/2015/684731/
The formation of naked singularities in dimensional powerlaw spacetimes in linear EinsteinMaxwell and Einsteinscalar theories sourced by azimuthally symmetric electric field and a selfinteracting real scalar field, respectively, are considered in view of quantum mechanics. Quantum test fields obeying the KleinGordon and Dirac equations are used to probe the classical timelike naked singularities developed at . We show that when the classically singular spacetimes probed with scalar waves, the considered spacetimes remain singular. However, the spinorial wave probe of the singularity in the metric of a selfinteracting real scalar field remains quantum regular. The notable outcome in this study is that the quantum regularity/singularity cannot be associated with the energy conditions.
O. Gurtug, M. Halilsoy, and S. Habib Mazharimousavi
Copyright © 2015 O. Gurtug et al. All rights reserved.

Will There Be Future Deceleration? A Study of Particle Creation Mechanism in Nonequilibrium Thermodynamics
Wed, 08 Apr 2015 06:15:04 +0000
http://www.hindawi.com/journals/ahep/2015/654025/
The paper deals with nonequilibrium thermodynamics based on adiabatic particle creation mechanism with the motivation of considering it as an alternative choice to explain the recent observed accelerating phase of the universe. Using Friedmann’s equations, it is shown that the deceleration parameter () can be obtained from the knowledge of the particle production rate (). Motivated by thermodynamical point of view, cosmological solutions are evaluated for the particle creation rates in three cosmic phases, namely, inflation, matter dominated era, and present late time acceleration. The deceleration parameter () is expressed as a function of the redshift parameter (), and its variation is presented graphically. Also, statefinder analysis has been presented graphically in three different phases of the universe. Finally, two noninteracting fluids with different particle creation rates are considered as cosmic substratum, and deceleration parameter () is evaluated. Whether more than one transition of is possible or not is examined by graphical representations.
Supriya Pan and Subenoy Chakraborty
Copyright © 2015 Supriya Pan and Subenoy Chakraborty. All rights reserved.

Decays with the QCD Factorization Approach
Sun, 05 Apr 2015 15:58:41 +0000
http://www.hindawi.com/journals/ahep/2015/104378/
We studied the nonleptonic , decays with the QCD factorization approach. It is found that the Cabibbo favored processes of , , are the promising decay channels with branching ratio larger than 1%, which should be observed earlier by the LHCb collaboration.
Junfeng Sun, Na Wang, Qin Chang, and Yueling Yang
Copyright © 2015 Junfeng Sun et al. All rights reserved.

Global Properties in High Energy Collisions
Thu, 26 Mar 2015 06:40:52 +0000
http://www.hindawi.com/journals/ahep/2015/895609/
BaoChun Li, Edward SarkisyanGrinbaum, Andrey Leonidov, Venktesh Singh, and C. Wu
Copyright © 2015 BaoChun Li et al. All rights reserved.

Transverse Momentum Distributions of Hadrons Produced in PbPb Collisions at LHC Energy TeV
Wed, 25 Mar 2015 12:35:10 +0000
http://www.hindawi.com/journals/ahep/2015/154853/
The transverse momentum spectra of several types of hadrons, , , , , , , , , , and produced in most central PbPb collisions at LHC energy TeV have been studied at midrapidity () using an earlier proposed unified statistical thermal freezeout model. The calculated results are found to be in good agreement with the experimental data measured by the ALICE experiment at LHC. The model calculation fits provide the thermal freezeout conditions in terms of the temperature and collective flow effect parameters for different particle species. Interestingly the model parameter fits to the experimental data reveal stronger collective flow in the system and lesser freezeout temperatures of the different particle species as compared to AuAu collisions at RHIC. The strong increase of the collective flow appears to be a consequence of the increasing particle density at LHC. The model used incorporates a longitudinal as well as transverse hydrodynamic flow. The chemical potential has been assumed to be nearly equal to zero for the bulk of the matter owing to high degree of nuclear transparency effect at such collision energies. The contributions from heavier decay resonances are also taken into account.
Saeed Uddin, Inamul Bashir, and Riyaz Ahmed Bhat
Copyright © 2015 Saeed Uddin et al. All rights reserved.

Search for LongRange Correlations in Relativistic HeavyIon Collisions at SPS Energies
Wed, 25 Mar 2015 12:18:55 +0000
http://www.hindawi.com/journals/ahep/2015/615458/
Longrange correlations are searched for by analysing the experimental data on 16OAgBr and 32SAgBr collisions at 200 A GeV/c and the results are compared with the predictions of a multi phase transport (AMPT) model. The findings reveal that the observed forwardbackward (FB) multiplicity correlations are mainly of short range in nature. The range of FB correlations are observed to extend with increasing projectile mass. The observed extended range of FB correlations might be due to overall multiplicity fluctuations arising because of nuclear geometry. The findings are not sufficient for making any definite conclusions regarding the presence of longrange correlations.
Shakeel Ahmad, Anisa Khatun, Shaista Khan, A. Ahmad, and M. Irfan
Copyright © 2015 Shakeel Ahmad et al. All rights reserved.

Tsallis Statistical Interpretation of Transverse Momentum Spectra in HighEnergy pA Collisions
Wed, 25 Mar 2015 11:16:53 +0000
http://www.hindawi.com/journals/ahep/2015/741816/
In Tsallis statistics, we investigate charged pion and proton production for pCu and pPb interactions at 3, 8, and 15 GeV/c. Two versions of Tsallis distribution are implemented in a multisource thermal model. A comparison with experimental data of the HARPCDP group shows that they both can reproduce the transverse momentum spectra, but the improved form gives a better description. It is also found that the difference between q and q′ is small when the temperature T = T′ for the same incident momentum and angular interval, and the value of q is greater than q′ in most cases.
BaoChun Li, Zhao Zhang, JunHui Kang, GuoXing Zhang, and FuHu Liu
Copyright © 2015 BaoChun Li et al. All rights reserved.

Charged Particle, Photon Multiplicity, and Transverse Energy Production in HighEnergy HeavyIon Collisions
Wed, 25 Mar 2015 08:45:54 +0000
http://www.hindawi.com/journals/ahep/2015/612390/
We review the charged particle and photon multiplicities and transverse energy production in heavyion collisions starting from few GeV to TeV energies. The experimental results of pseudorapidity distribution of charged particles and photons at different collision energies and centralities are discussed. We also discuss the hypothesis of limiting fragmentation and expansion dynamics using the Landau hydrodynamics and the underlying physics. Meanwhile, we present the estimation of initial energy density multiplied with formation time as a function of different collision energies and centralities. In the end, the transverse energy per charged particle in connection with the chemical freezeout criteria is discussed. We invoke various models and phenomenological arguments to interpret and characterize the fireball created in heavyion collisions. This review overall provides a scope to understand the heavyion collision data and a possible formation of a deconfined phase of partons via the global observables like charged particles, photons, and the transverse energy measurement.
Raghunath Sahoo, Aditya Nath Mishra, Nirbhay K. Behera, and Basanta K. Nandi
Copyright © 2015 Raghunath Sahoo et al. All rights reserved.

On Extraction of Chemical Potentials of Quarks from Particle Transverse Momentum Spectra in High Energy Collisions
Wed, 25 Mar 2015 08:19:30 +0000
http://www.hindawi.com/journals/ahep/2015/137058/
We present two methods to extract the chemical potentials of quarks in high energy collisions. The first method is based on the ratios of negatively/positively charged particles, and the temperatures extracted from the transverse momentum spectra of related hadrons are needed. The second method is based on the chemical potentials of some particles, and we also need the transverse momentum spectra of related hadrons. To extract the quark chemical potentials, we would like to propose experimental collaborations to measure simultaneously not only the transverse momentum spectra of , , , , , and , but also those of , , , and (even those of , , and ) in high energy nuclear collisions.
Hong Zhao and FuHu Liu
Copyright © 2015 Hong Zhao and FuHu Liu. All rights reserved.

Axially SymmetricdS Solution in Teleparallel Gravity Theories
Tue, 24 Mar 2015 13:41:00 +0000
http://www.hindawi.com/journals/ahep/2015/915928/
We apply a tetrad field with six unknown functions to Einstein field equations. Exact vacuum solution, which represents axially symmetricdS spacetime, is derived. We multiply the tetrad field of the derived solution by a local Lorentz transformation which involves a generalization of the angle and get a new tetrad field. Using this tetrad, we get a differential equation from the scalar torsion . Solving this differential equation we obtain a solution to the gravity theories under certain conditions on the form of and its first derivatives. Finally, we calculate the scalars of Riemann Christoffel tensor, Ricci tensor, Ricci scalar, torsion tensor, and its contraction to explain the singularities associated with this solution.
Gamal G. L. Nashed
Copyright © 2015 Gamal G. L. Nashed. All rights reserved.

Coupled Scalar Fields Oscillons and Breathers in Some Lorentz Violating Scenarios
Wed, 18 Mar 2015 10:10:57 +0000
http://www.hindawi.com/journals/ahep/2015/673716/
We discuss the impact of the breaking of the Lorentz symmetry on the usual oscillons,
the socalled flattop oscillons, and the breathers. Our analysis is performed by using a Lorentz violation
scenario rigorously derived in the literature. We show that the Lorentz violation is responsible
for the origin of a kind of deformation of the configuration, where the field configuration becomes
oscillatory in a localized region near its maximum value. Furthermore, we show that the Lorentz
breaking symmetry produces a displacement of the oscillon along the spatial direction; the same
feature is present in the case of breathers. We also show that the effect of a Lorentz violation in
the flattop oscillon solution is responsible by the shrinking of the flattop. Furthermore, we find
analytically the outgoing radiation; this result indicates that the amplitude of the outgoing radiation
is controlled by the Lorentz breaking parameter, in such a way that this oscillon becomes more
unstable than its symmetric counterpart; however, it still has a long living nature.
R. A. C. Correa and A. de Souza Dutra
Copyright © 2015 R. A. C. Correa and A. de Souza Dutra. All rights reserved.

Analytical Calculation of Stored Electrostatic Energy per Unit Length for an Infinite Charged Line and an Infinitely Long Cylinder in the Framework of BornInfeld Electrostatics
Tue, 17 Mar 2015 13:43:35 +0000
http://www.hindawi.com/journals/ahep/2015/180185/
More than 80 years ago, BornInfeld electrodynamics was proposed in order to remove the point charge singularity in Maxwell electrodynamics. In this work, after a brief introduction to Lagrangian formulation of Abelian BornInfeld model in the presence of an external source, we obtain the explicit forms of Gauss’s law and the energy density of an electrostatic field for BornInfeld electrostatics. The electric field and the stored electrostatic energy per unit length for an infinite charged line and an infinitely long cylinder in BornInfeld electrostatics are calculated. Numerical estimations in this paper show that the nonlinear corrections to Maxwell electrodynamics are considerable only for strong electric fields. We present an action functional for Abelian BornInfeld model with an auxiliary scalar field in the presence of an external source. This action functional is a generalization of the action functional which was presented by Tseytlin in his studies on low energy dynamics of Dbranes (Nucl. Phys. B469, 51 (1996); Int. J. Mod. Phys. A 19, 3427 (2004)). Finally, we derive the symmetric energymomentum tensor for Abelian BornInfeld model with an auxiliary scalar field.
S. K. Moayedi, M. Shafabakhsh, and F. Fathi
Copyright © 2015 S. K. Moayedi et al. All rights reserved.

The Quantum Effects Role on Weibel Instability Growth Rate in Dense Plasma
Sun, 15 Mar 2015 13:02:21 +0000
http://www.hindawi.com/journals/ahep/2015/746212/
The Weibel instability is one of the basic plasma instabilities that plays an important role in stopping the hot electrons and energy deposition mechanism. In this paper, combined effect of the density gradient and quantum effects on Weibel instability growth rate is investigated. The results have shown that, by increasing the quantum parameter, for large wavelengths, the Weibel instability growth rate shrinks to zero. In the large wavelengths limit, the analysis shows that quantum
effects and density gradient tend to stabilize the Weibel instability. The density perturbations have decreased the growth rate of Weibel instability in the near corona fuel, . In the small wavelengths limit, for the density gradient, , the tunneling quantum effects increase anisotropy in the phase space. The quantum tunneling effect leads to an unexpected increase in the Weibel instability growth rate.
M. Mahdavi and F. Khodadadi Azadboni
Copyright © 2015 M. Mahdavi and F. Khodadadi Azadboni. All rights reserved.

Retracted: Extracting the QCD Cutoff Parameter Using the Bernstein Polynomials and the Truncated Moments
Thu, 12 Mar 2015 07:23:10 +0000
http://www.hindawi.com/journals/ahep/2015/975023/
Advances in High Energy Physics
Copyright © 2015 Advances in High Energy Physics. All rights reserved.

Cosmological Evolution of Pilgrim Dark Energy in Gravity
Tue, 10 Mar 2015 14:16:36 +0000
http://www.hindawi.com/journals/ahep/2015/952156/
We analyze the behavior of pilgrim dark energy with Hubble horizon in gravity. We reconstruct the models through correspondence phenomenon by assuming two values of pilgrim dark energy parameter . We evaluate the equation of state parameter which shows evolution of the universe in the quintessence, vacuum, and phantom phase for both cases of and give favor the pilgrim dark energy phenomenon. Also, squared speed of sound exhibits the stability of model for both cases of . The also provides freezing and thawing regions in this scenario. In this framework, the plane also corresponds to different dark energy scenarios.
Abdul Jawad and Shamaila Rani
Copyright © 2015 Abdul Jawad and Shamaila Rani. All rights reserved.

Thermal Properties of Light Tensor Mesons via QCD Sum Rules
Tue, 10 Mar 2015 13:37:31 +0000
http://www.hindawi.com/journals/ahep/2015/794243/
The thermal properties of (1270), (1320), and (1430) light tensor mesons are investigated in the framework of QCD sum rules at finite temperature. In particular, the masses and decay constants of the light tensor mesons are calculated taking into account the new operators appearing at finite temperature. The numerical results show that, at the point at which the temperaturedependent continuum threshold vanishes, the decay constants decrease with amount of (70–85)% compared to their vacuum values, while the masses diminish about (60–72)% depending on the kinds of the mesons under consideration. The results obtained at zero temperature are in good consistency with the experimental data as well as the existing theoretical predictions.
K. Azizi, A. Türkan, E. Veli Veliev, and H. Sundu
Copyright © 2015 K. Azizi et al. All rights reserved.

Lepton Number Violation and Neutrino Masses in 331 Models
Tue, 10 Mar 2015 06:50:08 +0000
http://www.hindawi.com/journals/ahep/2015/813129/
Lepton number violation and its relation to neutrino masses are investigated in several versions of the model. Spontaneous and explicit violation and conservation of the lepton number are considered. In one of the models (the socalled economical one), the lepton number is spontaneously violated and it is found that the would be Majoron is not present because it is gauged away, providing in this way the longitudinal polarization component to a now massive gauge field.
Richard H. Benavides, Luis N. Epele, Huner Fanchiotti, Carlos García Canal, and William A. Ponce
Copyright © 2015 Richard H. Benavides et al. All rights reserved.

Quintessence and Holographic Dark Energy in Gravity
Mon, 09 Mar 2015 11:21:53 +0000
http://www.hindawi.com/journals/ahep/2015/292767/
We regard theory as an efficient tool to explain the current cosmic acceleration and associate its evolution with the known dark energy models. The numerical scheme is applied to reconstruct theory from dark energy model with constant equation of state parameter and holographic dark energy model. We set the model parameters and as describing the different evolution eras and show the distinctive behavior of each case realized in theory. We also present the future evolution of reconstructed and find that it is consistent with the recent observations.
M. Zubair
Copyright © 2015 M. Zubair. All rights reserved.

Neutron Interferometry at the National Institute of Standards and Technology
Mon, 09 Mar 2015 07:46:40 +0000
http://www.hindawi.com/journals/ahep/2015/687480/
Neutron interferometry has proved to be a very precise technique for measuring the quantum mechanical phase of a neutron caused by a potential energy difference between two spatially separated neutron paths inside interferometer. The path length inside the interferometer can be many centimeters (and many centimeters apart) making it very practical to study a variety of samples, fields, potentials, and other macroscopic medium and quantum effects. The precision of neutron interferometry comes at a cost; neutron interferometers are very susceptible to environmental noise that is typically mitigated with large, active isolated enclosures. With recent advances in quantum information processing especially quantum error correction (QEC) codes we were able to demonstrate a neutron interferometer that is insensitive to vibrational noise. A facility at NIST’s Center for Neutron Research (NCNR) has just been commissioned with higher neutron flux than the NCNR’s older interferometer setup. This new facility is based on QEC neutron interferometer, thus improving the accessibility of neutron interferometry to the greater scientific community and expanding its applications to quantum computing, gravity, and material research.
D. A. Pushin, M. G. Huber, M. Arif, C. B. Shahi, J. Nsofini, C. J. Wood, D. Sarenac, and D. G. Cory
Copyright © 2015 D. A. Pushin et al. All rights reserved.

Status of the GRANIT Facility
Mon, 09 Mar 2015 06:14:37 +0000
http://www.hindawi.com/journals/ahep/2015/730437/
The GRANIT facility is a followup project, which is motivated by the recent discovery of gravitational quantum states of ultracold neutrons. The goal of the project is to approach the ultimate accuracy in measuring parameters of such quantum states and also to apply this phenomenon and related experimental techniques to a broad range of applications in particle physics as well as in surface and nanoscience studies. We overview the current status of this facility, the recent test measurements, and the nearest prospects.
Damien Roulier, Francis Vezzu, Stefan Baeßler, Benoît Clément, Daniel Morton, Valery V. Nesvizhevsky, Guillaume Pignol, and Dominique Rebreyend
Copyright © 2015 Damien Roulier et al. All rights reserved.

Effect of Hadron Contamination on Dielectron Signal Reconstruction in Heavy Flavor Production Measurements
Sun, 08 Mar 2015 11:31:52 +0000
http://www.hindawi.com/journals/ahep/2015/385205/
Dielectron signal reconstruction is an important tool for heavy flavor measurements because of its trigger feasibility and its relatively straightforward particle identification process. However, in the case of time projection chamber detectors, some hadron contamination is unavoidable, even
if additional means are used to improve the particle identification process. In this paper, we investigate the effects of hadron (protons, pions, and kaons) contamination on the dielectron signal
reconstruction process in the measurement of and electrons from heavy
flavor hadron decays.
Daniel Kikoła
Copyright © 2015 Daniel Kikoła. All rights reserved.

Production and Decay of UpType and DownType New Heavy Quarks through Anomalous Interactions at the LHC
Sun, 08 Mar 2015 09:31:45 +0000
http://www.hindawi.com/journals/ahep/2015/134898/
We study the process (where and and ) through the anomalous interactions of the new heavy quarks at the LHC. Considering the present limits on the masses and mixings, the signatures of the heavy quark anomalous interactions are discussed and analysed at the LHC for the center of mass energy of 13 TeV. An important sensitivity to anomalous couplings TeV−1, TeV−1, TeV−1 and TeV−1, TeV−1, TeV−1 for the mass of 750 GeV of the new heavy quarks and can be reached for an integrated luminosity of fb−1.
İ. T. Çakır, S. Kuday, and O. Çakır
Copyright © 2015 İ. T. Çakır et al. All rights reserved.

Neutron Scattering on Impurity Nanoclusters in Gel Samples
Sun, 08 Mar 2015 08:47:36 +0000
http://www.hindawi.com/journals/ahep/2015/808212/
Results of recent SANS experiments with impurityhelium gel (IHG) samples in HeII are presented. We estimate the mean size of the impurity nanoparticles that form the frame of the IHG samples and discuss the possibility to use IHG samples for the production of ultracold neutrons (UCNs) in HeII cooled to the temperature of a few mK, as well as the reflection of UCNs at any temperature. Our results indicate that the most promising materials for these purposes might be the heavy water gel samples with the mean sizes of D2O clusters of d~8 nm and the heavy alcohol gel samples with the mean sizes of clusters of d~15 nm.
V. B. Efimov, L. P. MezhovDeglin, C. D. Dewhurst, A. V. Lokhov, and V. V. Nesvizhevsky
Copyright © 2015 V. B. Efimov et al. All rights reserved.

UCN Source at an External Beam of Thermal Neutrons
Sun, 08 Mar 2015 08:40:11 +0000
http://www.hindawi.com/journals/ahep/2015/547620/
We propose a new method for production of ultracold neutrons (UCNs) in superfluid helium. The principal idea consists in installing a helium UCN source into an external beam of thermal or cold neutrons and in surrounding this source with a solid methane moderator/reflector cooled down to ~4 K. The moderator plays the role of an external source of cold neutrons needed to produce UCNs. The flux of accumulated neutrons could exceed the flux of incident neutrons due to their numerous reflections from methane; also the source size could be significantly larger than the incident beam diameter. We provide preliminary calculations of cooling of neutrons. These calculations show that such a source being installed at an intense source of thermal or cold neutrons like the ILL or PIK reactor or the ESS spallation source could provide the UCN density 105 cm−3, the production rate 107 UCN/s−1. Main advantages of such an UCN source include its low radiative and thermal load, relatively low cost, and convenient accessibility for any maintenance. We have carried out an experiment on cooling of thermal neutrons in a methane cavity. The data confirm the results of our calculations of the spectrum and flux of neutrons in the methane cavity.
E. V. Lychagin, A. Yu. Muzychka, G. V. Nekhaev, V. V. Nesvizhevsky, E. I. Sharapov, and A. V. Strelkov
Copyright © 2015 E. V. Lychagin et al. All rights reserved.

Prospects for Studies of the Free Fall and Gravitational Quantum States of Antimatter
Sun, 08 Mar 2015 08:16:45 +0000
http://www.hindawi.com/journals/ahep/2015/379642/
Different experiments are ongoing to measure the effect of gravity on cold neutral antimatter atoms such as positronium, muonium, and antihydrogen. Among those, the project GBAR at CERN aims to measure precisely the gravitational fall of ultracold antihydrogen atoms. In the ultracold regime, the interaction of antihydrogen atoms with a surface is governed by the phenomenon of quantum reflection which results in bouncing of antihydrogen atoms on matter surfaces. This allows the application of a filtering scheme to increase the precision of the free fall measurement. In the ultimate limit of smallest vertical velocities, antihydrogen atoms are settled in gravitational quantum states in close analogy to ultracold neutrons (UCNs). Positronium is another neutral system involving antimatter for which free fall under gravity is currently being investigated at UCL. Building on the experimental techniques under development for the free fall measurement, gravitational quantum states could also be observed in positronium. In this contribution, we report on the status of the ongoing experiments and discuss the prospects of observing gravitational quantum states of antimatter and their implications.
G. Dufour, D. B. Cassidy, P. Crivelli, P. Debu, A. Lambrecht, V. V. Nesvizhevsky, S. Reynaud, A. Yu. Voronin, and T. E. Wall
Copyright © 2015 G. Dufour et al. All rights reserved.

Can We Observe the Gravitational Quantum States of Positronium?
Sun, 08 Mar 2015 07:48:42 +0000
http://www.hindawi.com/journals/ahep/2015/173572/
We consider the feasibility of observing the gravitational quantum states of positronium. The proposed scheme employs the flowthrow technique used for the first observation of this effect with neutrons. Collimation and Stark deceleration of Rydberg positronium atoms allow selecting the required velocity class. If this experiment could be realized with positronium, it would lead to a determination of for this matterantimatter system at the few % level. As discussed in this contribution, most of the required techniques are currently available but important milestones have to be demonstrated experimentally before such an experiment could become reality. Those are the efficient focusing of a bunched positron beam, Stark deceleration of Rydberg positronium, and its subsequent excitation into states with large angular momentum. We provide an estimate of the efficiencies we expect for these steps and assuming those could be confirmed we calculate the signal rate.
P. Crivelli, V. V. Nesvizhevsky, and A. Yu. Voronin
Copyright © 2015 P. Crivelli et al. All rights reserved.

Phase Transition of the Higher Dimensional Charged GaussBonnet Black Hole in de Sitter Spacetime
Sun, 01 Mar 2015 12:23:51 +0000
http://www.hindawi.com/journals/ahep/2015/134815/
We study the phase transition of charged GaussBonnetde Sitter (GBdS) black hole. For black
holes in de Sitter spacetime, there is not only black hole horizon, but also cosmological horizon.
The thermodynamic quantities on both horizons satisfy the first law of the black hole thermodynamics,
respectively; moreover, there are additional connections between them. Using the effective
temperature approach, we obtained the effective thermodynamic quantities of charged GBdS black
hole. According to Ehrenfest classification, we calculate some response functions and plot their
figures, from which one can see that the spacetime undergoes a secondorder phase transition at
the critical point. It is shown that the critical values of effective temperature and pressure decrease
with the increase of the value of GB parameter .
MengSen Ma, LiChun Zhang, HuiHua Zhao, and Ren Zhao
Copyright © 2015 MengSen Ma et al. All rights reserved.

Weak Minimal Area in Entanglement Entropy
Thu, 26 Feb 2015 11:22:35 +0000
http://www.hindawi.com/journals/ahep/2015/523408/
We revisit the minimal area condition of RyuTakayanagi in the holographic calculation of the entanglement entropy, in particular, the Legendre test and the Jacobi test. The necessary condition for the weak minimality is checked via Legendre test and its sufficient nature via Jacobi test. We show for AdS black hole with a strip type entangling region that it is this minimality condition that makes the hypersurface unable to cross the horizon, which is in agreement with that studied earlier by Engelhardt et al. and Hubeny using a different approach. Moreover, demanding the weak minimality condition on the entanglement entropy functional with the higher derivative term puts a constraint on the GaussBonnet coupling; that is, there should be an upper bound on the value of the coupling, .
Shesansu Sekhar Pal and Shubhalaxmi Rath
Copyright © 2015 Shesansu Sekhar Pal and Shubhalaxmi Rath. All rights reserved.

Theoretical and Phenomenological Status of Neutrino Physics: A Brief Review
Wed, 25 Feb 2015 07:36:04 +0000
http://www.hindawi.com/journals/ahep/2015/385968/
We present an overview of recent progress in the theoretical and phenomenological studies of neutrino masses, lepton avor mixing, and CP violation. Firstly, We discuss the status of neutrino mass with in the Standard Model (SM) of particle physics. Then the possible ways in which neutrino mass terms can be included in the SM are discussed. The inclusion of new physics beyond the SM inevitably brings new parameters which are not constrained by the present
experimental data on neutrino masses and mixing angles and, thus, are free parameters of the theory. We, also, discuss various theoretically motivated phenomenological approaches which can be used to reduce the number of free parameters and, thus, provide an excellent tool to understand the underlying physics of neutrino masses and mixings. Current experimental constraints on
the neutrino mass spectrum and the lepton avor mixing parameters, including the recent observation of nonzero , have been summarized. Finally, We discuss the renewed interest in the possible existence of one or more sterile
neutrinos and their phenomenology.
Surender Verma
Copyright © 2015 Surender Verma. All rights reserved.