Advances in High Energy Physics The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. New Directions in Direct Dark Matter Searches Wed, 16 Apr 2014 11:45:13 +0000 I present the status of direct dark matter detection with specific attention to the experimental results and their phenomenological interpretation in terms of dark matter interactions. In particular I review a new and more general approach to study signals in this field based on nonrelativistic operators which parametrize more efficiently the dark matter-nucleus interactions in terms of a very limited number of relevant degrees of freedom. Then I list the major experimental results, pointing out the main uncertainties that affect the theoretical interpretation of the data. Finally, since the underlying theory that describes both the dark matter and the standard model fields is unknown, I address the uncertainties coming from the nature of the interaction. In particular, the phenomenology of a class of models in which the interaction between dark matter particles and target nuclei is of a long range type is discussed. Paolo Panci Copyright © 2014 Paolo Panci. All rights reserved. Decaying Dark Atom Constituents and Cosmic Positron Excess Wed, 16 Apr 2014 11:00:35 +0000 We present a scenario where dark matter is in the form of dark atoms that can accommodate the experimentally observed excess of positrons in PAMELA and AMS-02 while being compatible with the constraints imposed on the gamma-ray ux from Fermi/LAT. This scenario assumes that the dominant component of dark matter is in the form of a bound state between a helium nucleus and a particle and a small component is in the form of a WIMP-like dark atom compatible with direct searches in underground detectors. One of the constituents of this WIMP-like state is a metastable particle with a mass of 1 TeV or slightly below that by decaying to , and produces the observed positron excess. These decays can naturally take place via GUT interactions. If it exists, such a metastable particle can be found in the next run of LHC. The model predicts also the ratio of leptons over baryons in the universe to be close to . K. Belotsky, M. Khlopov, C. Kouvaris, and M. Laletin Copyright © 2014 K. Belotsky et al. All rights reserved. Hubble Parameter Corrected Interactions in Cosmology Mon, 14 Apr 2014 11:07:30 +0000 We make steps in a new direction by considering fluids with EoS of more general form . It is thought that there should be interaction between cosmic fluids, but this assumption for this stage carries only phenomenological character opening a room for different kinds of manipulations. In this paper we will consider a modification of an interaction , where we accept that interaction parameter (order of unity) in is time dependent and presented as a linear function of Hubble parameter of the form , where and are constants. We consider two different models including modified Chaplygin gas and polytropic gas which have bulk viscosity. Then, we investigate problem numerically and analyze behavior of different cosmological parameters concerning fluids and behavior of the universe. J. Sadeghi, M. Khurshudyan, M. Hakobyan, and H. Farahani Copyright © 2014 J. Sadeghi et al. All rights reserved. Transverse Momentum Distributions in AuAu and dAu Collisions at  GeV Thu, 10 Apr 2014 10:10:33 +0000 We study the transverse momentum distributions of identified particles produced in Au + Au and d + Au collisions at  GeV. The Tsallis description is applied in the multisource model. The results are compared with the experimental data in detail. We obtain some information of the thermodynamic properties of matter produced in the collisions. The difference of the transverse momentum distributions in Au + Au and d + Au collisions is not significant. Li-Li Wang Copyright © 2014 Li-Li Wang. All rights reserved. Comparing Multicomponent Erlang Distribution and Lévy Distribution of Particle Transverse Momentums Thu, 10 Apr 2014 00:00:00 +0000 The transverse momentum spectrums of final-state products produced in nucleus-nucleus and proton-proton collisions at different center-of-mass energies are analyzed by using a multicomponent Erlang distribution and the Lévy distribution. The results calculated by the two models are found in most cases to be in agreement with experimental data from the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). The multicomponent Erlang distribution that resulted from a multisource thermal model seems to give a better description as compared with the Lévy distribution. The temperature parameters of interacting system corresponding to different types of final-state products are obtained. Light particles correspond to a low temperature emission, and heavy particles correspond to a high temperature emission. Extracted temperature from central collisions is higher than that from peripheral collisions. Hua-Rong Wei, Ya-Hui Chen, Li-Na Gao, and Fu-Hu Liu Copyright © 2014 Hua-Rong Wei et al. All rights reserved. Analyzing the Anomalous Dipole Moment Type Couplings of Heavy Quarks with FCNC Interactions at the CLIC Wed, 09 Apr 2014 13:26:37 +0000 We examine both anomalous magnetic and dipole moment type couplings of a heavy quark via its single production with subsequent dominant standard model decay modes at the compact linear collider (CLIC). The signal and background cross sections are analyzed for heavy quark masses 600 and 700 GeV. We make the analysis to delimitate these couplings as well as to find the attainable integrated luminosities for observation limit. A. T. Tasci, A. Senol, and C. Verep Copyright © 2014 A. T. Tasci et al. All rights reserved. What Can We Learn from (Pseudo)Rapidity Distribution in High Energy Collisions? Tue, 08 Apr 2014 07:05:25 +0000 Based on the (pseudo)rapidity distribution of final-state particles produced in proton-proton (pp) collisions at high energy, the probability distributions of momenta, longitudinal momenta, transverse momenta (transverse masses), energies, velocities, longitudinal velocities, transverse velocities, and emission angles of the considered particles are obtained in the framework of a multisource thermal model. The number density distributions of particles in coordinate and momentum spaces and related transverse planes, the particle dispersion plots in longitudinal and transverse coordinate spaces, and the particle dispersion plots in transverse momentum plane at the stage of freeze out in high energy pp collisions are also obtained. Fu-Hu Liu, Tian Tian, Jian-Xin Sun, and Bao-Chun Li Copyright © 2014 Fu-Hu Liu et al. All rights reserved. Shower and Slow Particle Productions in Nucleus-Nucleus Collisions at High Energy Mon, 07 Apr 2014 09:02:44 +0000 The multiplicity distributions of shower, grey, and black particles produced in interactions of 4He, 12C, 16O, 22Ne, and 28Si with emulsion (Em) at 4.1–4.5 A GeV/c beam energies, and their dependence on target groups (H, CNO, and AgBr) is presented and has been reproduced by multisource thermal model. The multiplicity and the angular distributions of the three types of particles have been investigated. The experimental results are compared with the corresponding ones from the model. We found that the experimental data agrees with theoretical calculations using multisource thermal model. S. Fakhraddin, Magda A. Rahim, and Hamdy M. M. Zayd Copyright © 2014 S. Fakhraddin et al. All rights reserved. The Evolution-Dominated Hydrodynamic Model and the Pseudorapidity Distributions in High Energy Physics Thu, 03 Apr 2014 14:11:56 +0000 By taking into account the effects of leading particles, we discuss the pseudorapidity distributions of the charged particles produced in high energy heavy ion collisions in the context of evolution-dominated hydrodynamic model. The leading particles are supposed to have a Gaussian rapidity distribution normalized to the number of participants. A comparison is made between the theoretical results and the experimental measurements performed by BRAHMS and PHOBOS Collaboration at BNL-RHIC in Au-Au and Cu-Cu collisions at  GeV and by ALICE Collaboration at CERN-LHC in Pb-Pb collisions at  TeV. Z. J. Jiang, H. L. Zhang, J. Wang, and K. Ma Copyright © 2014 Z. J. Jiang et al. All rights reserved. Hermitian -Freudenthal-Kantor Triple Systems and Certain Applications of *-Generalized Jordan Triple Systems to Field Theory Thu, 03 Apr 2014 09:57:27 +0000 We define Hermitian -Freudenthal-Kantor triple systems and prove a structure theorem. We also give some examples of triple systems that are generalizations of the and Hermitian 3-algebras. We apply a -generalized Jordan triple system to a field theory and obtain a Chern-Simons gauge theory. We find that the novel Higgs mechanism works, where the Chern-Simons gauge theory reduces to a Yang-Mills theory in a certain limit. Noriaki Kamiya and Matsuo Sato Copyright © 2014 Noriaki Kamiya and Matsuo Sato. All rights reserved. Analyzing Black Hole Super-Radiance Emission of Particles/Energy from a Black Hole as a Gedankenexperiment to Get Bounds on the Mass of a Graviton Thu, 03 Apr 2014 09:27:31 +0000 Use of super-radiance in BH physics, so specifies conditions for a mass of a graviton being less than or equal to 1065 grams, allows for determing what role additional dimensions may play in removing the datum that massive gravitons lead to 3/4th the bending of light past the planet Mercury. The present document makes a given differentiation between super-radiance in the case of conventional BHs and Braneworld BH super-radiance, which may delineate whether Braneworlds contribute to an admissible massive graviton in terms of removing the usual problem of the 3/4th the bending of light past the planet Mercury which is normally associated with massive gravitons. This leads to a fork in the road between two alternatives with the possibility of needing a multiverse containment of BH structure or embracing what Hawkings wrote up recently, namely, a redo of the event horizon hypothesis as we know it. A. Beckwith Copyright © 2014 A. Beckwith. All rights reserved. Studies of Three-Body Decay of to and to * Thu, 03 Apr 2014 00:00:00 +0000 We investigate the and decay by using the Dalitz plot analysis. As we know there are tree, penguin, emission, and emission-annihilation diagrams for these decay modes in the factorization approach. The transition matrix element is factorized into a form factor multiplied by decay constant and also a form factor multiplied by decay constant. According to QCD factorization approach and using the Dalitz plot analysis, we calculate the branching ratios of the and three-body decay in view of the mixing and obtain the value of the , while the experimental results of them are and , respectively. In this research we also analyze the decay which is similar to the previous decay, but there is no experimental data for the last decay. Since for calculations of the decay we use assumptions of the decay, we hope that if this decay will be measured by the LHCb in the future, the experimental results will be in agreement with our calculations. Behnam Mohammadi and Hossein Mehraban Copyright © 2014 Behnam Mohammadi and Hossein Mehraban. All rights reserved. Magnetic String with a Nonlinear Source Wed, 02 Apr 2014 14:16:28 +0000 Considering the Einstein gravity in the presence of Born-Infeld type electromagnetic fields, we introduce a class of 4-dimensional static horizonless solutions which produce longitudinal magnetic fields. Although these solutions do not have any curvature singularity and horizon, there exists a conic singularity. We investigate the effects of nonlinear electromagnetic fields on the properties of the solutions and find that the asymptotic behavior of the solutions is adS. Next, we generalize the static metric to the case of rotating solutions and find that the value of the electric charge depends on the rotation parameter. Furthermore, conserved quantities will be calculated through the use of the counterterm method. Finally, we extend four-dimensional magnetic solutions to higher dimensional solutions. We present higher dimensional rotating magnetic branes with maximum rotation parameters and obtain their conserved quantities. S. H. Hendi Copyright © 2014 S. H. Hendi. All rights reserved. Holographic Brownian Motion in Three-Dimensional Gödel Black Hole Wed, 02 Apr 2014 11:38:36 +0000 By using the AdS/CFT correspondence and Gödel black hole background, we study the dynamics of heavy quark under a rotating plasma. In that case we follow Atmaja (2013) about Brownian motion in BTZ black hole. In this paper we receive some new results for the case of . In this case, we must redefine the angular velocity of string fluctuation. We obtain the time evolution of displacement square and angular velocity and show that it behaves as a Brownian particle in non relativistic limit. In this plasma, it seems that relating the Brownian motion to physical observables is rather a difficult work. But our results match with Atmaja work in the limit . J. Sadeghi, F. Pourasadollah, and H. Vaez Copyright © 2014 J. Sadeghi et al. All rights reserved. A New Flavor Symmetry in 3-3-1 Model with Neutral Fermions Wed, 02 Apr 2014 09:02:35 +0000 A new S4 flavor model based on gauge symmetry responsible for fermion masses and mixings is constructed. The neutrinos get small masses from only an antisextet of SU(3)L which is in a doublet under S4. In this work, we assume the VEVs of the antisextet differ from each other under S4 and the difference of these VEVs is regarded as a small perturbation, and then the model can fit the experimental data on neutrino masses and mixings. Our results show that the neutrino masses are naturally small and a deviation from the tribimaximal neutrino mixing form can be realized. The quark masses and mixing matrix are also discussed. The number of required Higgs multiplets is less and the scalar potential of the model is simpler than those of the model based on S3 and our previous S4 model. The assignation of VEVs to antisextet leads to the mixing of the new gauge bosons and those in the standard model. The mixing in the charged gauge bosons as well as the neutral gauge bosons is considered. V. V. Vien and H. N. Long Copyright © 2014 V. V. Vien and H. N. Long. All rights reserved. How Can the Modified Dispersion Relation Affect Friedmann Equations? Tue, 01 Apr 2014 13:42:45 +0000 The appearance of the quantum gravitational effects in a very high energy regime necessitates some corrections to the thermodynamics of Friedmann-Robertson-Walker (FRW) universe. The modified dispersion relation (MDR) as a phenomenological approach to investigate the high energy physics provides a perturbation framework upon which the FRW universe thermodynamics can be corrected. In this letter, we obtain the corrected entropy-area relation of the apparent horizon of FRW universe by utilizing the extra dimensional form of MDR, leading to the modification of Friedmann equations. The influence of MDR on the Friedmann equations provides a good insight into the understanding of the FRW universe dynamics in the final quantum gravity theory. A. S. Sefiedgar Copyright © 2014 A. S. Sefiedgar. All rights reserved. MicroBlack Holes Thermodynamics in the Presence of Quantum Gravity Effects Tue, 01 Apr 2014 10:18:41 +0000 Black hole thermodynamics is corrected in the presence of quantum gravity effects. Some phenomenological aspects of quantum gravity proposal can be addressed through generalized uncertainty principle (GUP) which provides a perturbation framework to perform required modifications of the black hole quantities. In this paper, we consider the effects of both a minimal measurable length and a maximal momentum on the thermodynamics of TeV-scale black holes. We then extend our study to the case that there are all natural cutoffs as minimal length, minimal momentum, and maximal momentum simultaneously. We also generalize our study to the model universes with large extra dimensions (LED). In this framework existence of black holes remnants as a possible candidate for dark matter is discussed. We study probability of black hole production in the Large Hadronic Collider (LHC) and we show this rate decreasing for sufficiently large values of the GUP parameter. H. Soltani, A. Damavandi Kamali, and K. Nozari Copyright © 2014 H. Soltani et al. All rights reserved. Halo-Independent Comparison of Direct Dark Matter Detection Data Tue, 01 Apr 2014 06:57:39 +0000 We review the halo-independent formalism that allows comparing data from different direct dark matter detection experiments without making assumptions on the properties of the dark matter halo. We apply this method to spin-independent WIMP-nuclei interactions, for both isospin-conserving and isospin-violating couplings, and to WIMPs interacting through an anomalous magnetic moment. Eugenio Del Nobile Copyright © 2014 Eugenio Del Nobile. All rights reserved. Neutrino Masses and Oscillations Sun, 30 Mar 2014 12:53:53 +0000 Elisa Bernardini, Leslie Camilleri, Vincenzo Flaminio, Srubabati Goswami, and Seon-Hee Seo Copyright © 2014 Elisa Bernardini et al. All rights reserved. Black Component of Dark Matter Sun, 30 Mar 2014 11:32:32 +0000 A mechanism of primordial black hole formation with specific mass spectrum is discussed. It is shown that these black holes could contribute to the energy density of dark matter. Our approach is elaborated in the framework of universal extra dimensions. A. V. Grobov, S. G. Rubin, and V. Yu. Shalamova Copyright © 2014 A. V. Grobov et al. All rights reserved. NMC and the Fine-Tuning Problem on the Brane Sun, 30 Mar 2014 10:17:19 +0000 We propose a new solution to the fine-tuning problem related to coupling constant of the potential. We study a quartic potential of the form in the framework of the Randall-Sundrum type II braneworld model in the presence of a Higgs field which interacts nonminimally with gravity via a possible interaction term of the form . Using the conformal transformation techniques, the slow-roll parameters in high energy limit are reformulated in the case of a nonminimally coupled scalar field. We show that, for some value of a coupling parameter and brane tension , we can eliminate the fine-tuning problem. Finally, we present graphically the solutions of several values of the free parameters of the model. A. Safsafi and M. Bennai Copyright © 2014 A. Safsafi and M. Bennai. All rights reserved. Double-Differential Production Cross Sections of Charged Pions in Charged Pion Induced Nuclear Reactions at High Momentums Sun, 30 Mar 2014 07:19:56 +0000 The double-differential production cross sections in interactions of charged pions on targets at high momentums are analyzed by using a multicomponent Erlang distribution which is obtained in the framework of a multisource thermal model. The calculated results are compared and found to be in agreement with the experimental data at the incident momentums of 3, 5, 8, and 12 GeV/c measured by the HARP Collaboration. It is found that the source contributions to the mean momentum of charged particles and to the distribution width of particle momentums decrease with increase of the emission angle, and the source number and temperature do not show an obvious dependence on the emission angle of the considered particle. Ya-Qin Gao, Tian Tian, S. Fakhraddin, Magda A. Rahim, and Fu-Hu Liu Copyright © 2014 Ya-Qin Gao et al. All rights reserved. Holographic Screens in Ultraviolet Self-Complete Quantum Gravity Thu, 27 Mar 2014 07:26:37 +0000 This paper studies the geometry and the thermodynamics of a holographic screen in the framework of the ultraviolet self-complete quantum gravity. To achieve this goal we construct a new static, neutral, nonrotating black hole metric, whose outer (event) horizon coincides with the surface of the screen. The spacetime admits an extremal configuration corresponding to the minimal holographic screen and having both mass and radius equalling the Planck units. We identify this object as the spacetime fundamental building block, whose interior is physically unaccessible and cannot be probed even during the Hawking evaporation terminal phase. In agreement with the holographic principle, relevant processes take place on the screen surface. The area quantization leads to a discrete mass spectrum. An analysis of the entropy shows that the minimal holographic screen can store only one byte of information, while in the thermodynamic limit the area law is corrected by a logarithmic term. Piero Nicolini and Euro Spallucci Copyright © 2014 Piero Nicolini and Euro Spallucci. All rights reserved. Challenges in Double Beta Decay Wed, 26 Mar 2014 13:59:01 +0000 In the past ten years, neutrino oscillation experiments have provided the incontrovertible evidence that neutrinos mix and have finite masses. These results represent the strongest demonstration that the electroweak Standard Model is incomplete and that new Physics beyond it must exist. In this scenario, a unique role is played by the Neutrinoless Double Beta Decay searches which can probe lepton number conservation and investigate the Dirac/Majorana nature of the neutrinos and their absolute mass scale (hierarchy problem) with unprecedented sensitivity. Today Neutrinoless Double Beta Decay faces a new era where large-scale experiments with a sensitivity approaching the so-called degenerate-hierarchy region are nearly ready to start and where the challenge for the next future is the construction of detectors characterized by a tonne-scale size and an incredibly low background. A number of new proposed projects took up this challenge. These are based either on large expansions of the present experiments or on new ideas to improve the technical performance and/or reduce the background contributions. In this paper, a review of the most relevant ongoing experiments is given. The most relevant parameters contributing to the experimental sensitivity are discussed and a critical comparison of the future projects is proposed. Oliviero Cremonesi and Maura Pavan Copyright © 2014 Oliviero Cremonesi and Maura Pavan. All rights reserved. Wormhole Solutions in the Presence of Nonlinear Maxwell Field Wed, 26 Mar 2014 09:17:52 +0000 In generalizing the Maxwell field to nonlinear electrodynamics, we look for the magnetic solutions. We consider a suitable real metric with a lower bound on the radial coordinate and investigate the properties of the solutions. We find that in order to have a finite electromagnetic field near the lower bound, we should replace the Born-Infeld theory with another nonlinear electrodynamics theory. Also, we use the cut-and-paste method to construct wormhole structure. We generalize the static solutions to rotating spacetime and obtain conserved quantities. S. H. Hendi Copyright © 2014 S. H. Hendi. All rights reserved. Lepton Flavour Violation Experiments Thu, 20 Mar 2014 12:50:29 +0000 Lepton Flavour Violation in the charged lepton sector (CLFV) is forbidden in the Minimal Standard model and strongly suppressed in extensions of the model to include finite neutrino mixing. On the other hand, a wide class of Supersymmetric theories, even coupled with Grand Unification models (SUSY-GUT models), predict CLFV processes at a rate within the reach of new experimental searches operated with high resolution detectors at high intensity accelerators. As the Standard model background is negligible, the observation of one or more CLFV events would provide incontrovertible evidence for physics beyond Standard model, while a null effect would severely constrain the set of theory parameters. Therefore, a big experimental effort is currently (and will be for incoming years) accomplished to achieve unprecedented sensitivity on several CLFV processes. In this paper we review past and recent results in this research field, with focus on CLFV channels involving muons and tau's. We present currently operating experiments as well as future projects, with emphasis laid on how sensitivity enhancements are accompanied by improvements on detection techniques. Limitations due to systematic effects are also discussed in detail together with the solutions being adopted to overcome them. F. Cei and D. Nicolò Copyright © 2014 F. Cei and D. Nicolò. All rights reserved. Black Holes and Quantum Mechanics Thu, 20 Mar 2014 12:14:44 +0000 We look at black holes from different, novel perspectives. B. G. Sidharth Copyright © 2014 B. G. Sidharth. All rights reserved. Hulthén and Coulomb-Like Potentials as a Tensor Interaction within the Relativistic Symmetries of the Manning-Rosen Potential Thu, 20 Mar 2014 09:03:04 +0000 The bound-state solutions of the Dirac equation for the Manning-Rosen potential are presented approximately for arbitrary spin-orbit quantum number with the Hulthén and Coulomb-like potentials as a tensor interaction. The generalized parametric Nikiforov-Uvarov (NU) method is used to obtain energy eigenvalues and corresponding two-component spinors of the two Dirac particles and these are obtained in the closed form by using the framework of the spin symmetry and p-spin symmetry concept. We have also shown that tensor interaction removes degeneracies between spin and p-spin doublets. Some numerical results are also given. Hadi Tokmehdashi, Ali Akbar Rajabi, and Majid Hamzavi Copyright © 2014 Hadi Tokmehdashi et al. All rights reserved. Theory and Phenomenology of Space-Time Defects Thu, 20 Mar 2014 06:59:37 +0000 Whether or not space-time is fundamentally discrete is of central importance for the development of the theory of quantum gravity. If the fundamental description of spacetime is discrete, typically represented in terms of a graph or network, then the apparent smoothness of geometry on large scales should be imperfect—it should have defects. Here, we review a model for space-time defects and summarize the constraints on the prevalence of these defects that can be derived from observation. Sabine Hossenfelder Copyright © 2014 Sabine Hossenfelder. All rights reserved. Inflation and Topological Phase Transition Driven by Exotic Smoothness Wed, 19 Mar 2014 12:40:34 +0000 We will discuss a model which describes the cause of inflation by a topological transition. The guiding principle is the choice of an exotic smoothness structure for the space-time. Here we consider a space-time with topology . In case of an exotic , there is a change in the spatial topology from a 3-sphere to a homology 3-sphere which can carry a hyperbolic structure. From the physical point of view, we will discuss the path integral for the Einstein-Hilbert action with respect to a decomposition of the space-time. The inclusion of the boundary terms produces fermionic contributions to the partition function. The expectation value of an area (with respect to some surface) shows an exponential increase; that is, we obtain inflationary behavior. We will calculate the amount of this increase to be a topological invariant. Then we will describe this transition by an effective model, the Starobinski or model which is consistent with the current measurement of the Planck satellite. The spectral index and other observables are also calculated. Torsten Asselmeyer-Maluga and Jerzy Król Copyright © 2014 Torsten Asselmeyer-Maluga and Jerzy Król. All rights reserved.