Showing papers in "International Journal of Modern Physics A in 2011"
TL;DR: In this article, the theoretical status of squark and gluino hadroproduction at the Tevatron and at the LHC was reviewed and numerical predictions were provided for all pair-production processes with a particular emphasis on proton-proton collisions at 7 TeV.
Abstract: We review the theoretical status of squark and gluino hadroproduction and provide numerical predictions for all squark and gluino pair-production processes at the Tevatron and at the LHC, with a particular emphasis on proton–proton collisions at 7 TeV. Our predictions include next-to-leading order supersymmetric QCD corrections and the resummation of soft gluon emission at next-to-leading-logarithmic accuracy. We discuss the impact of the higher-order corrections on total cross-sections, and provide an estimate of the theoretical uncertainty due to scale variation and the parton distribution functions.
308 citations
TL;DR: In this article, a review of the aspects of Lifshitz-type field theories in Particle Physics is presented, including the improvement of graphs convergence, the introduction of new renormalizable interactions, dynamical mass generation, asymptotic freedom, and other features related to more specific models.
Abstract: This introduction to Lifshitz-type field theories reviews some of its aspects in Particle Physics. Attractive features of these models are described with different examples, as the improvement of graphs convergence, the introduction of new renormalizable interactions, dynamical mass generation, asymptotic freedom, and other features related to more specific models. On the other hand, problems with the expected emergence of Lorentz symmetry in the IR are discussed, related to the different effective light cones seen by different particles when they interact.
82 citations
TL;DR: A review of the experimental searches for new particles in the dijet mass spectrum conducted at the CERN $S\bar{p}pS, the Fermilab Tevatron Collider, and the Cern Large Hadron Collider is presented in this paper.
Abstract: We review the experimental searches for new particles in the dijet mass spectrum conducted at the CERN $S\bar{p}pS$, the Fermilab Tevatron Collider, and the CERN Large Hadron Collider. The theory of the QCD background and new particle signals is reviewed, with emphasis on the choices made by the experiments to model the background and signal. The experimental techniques, data, and results of dijet resonance searches at hadron colliders over the last quarter century are described and compared. Model independent and model specific limits on new particles decaying to dijets are reviewed, and a detailed comparison is made of the recently published limits from the ATLAS and CMS experiments.
74 citations
TL;DR: In this paper, the authors review recent work in developing linear sigma model techniques aimed at elucidating the underlying worldsheet description of the heterotic string compactification, and propose a linear sigmoid model to solve the problem.
Abstract: Compactifications of the heterotic string are a viable route to phenomenologically realistic vacua and interesting new mathematics. While supergravity aspects of heterotic compactifications are largely well-understood their worldsheet description remains largely unexplored. We review recent work in developing linear sigma model techniques aimed at elucidating the underlying worldsheet description.
73 citations
TL;DR: In this paper, the authors considered the gravity dual of strongly coupled systems at a Lifshitz fixed point and finite temperature, and constructed an Abelian-Higgs model in that background and calculate condensation and conductivity using holographic techniques.
Abstract: We consider the gravity dual of strongly coupled system at a Lifshitz-fixed point and finite temperature, which was constructed in a recent work arXiv:0909.0263. We construct an Abelian-Higgs model in that background and calculate condensation and conductivity using holographic techniques. We find that condensation happens and DC conductivity blows up when temperature turns below a critical value. We also study the zero temperature limit of strongly coupled system at the Lifshitz-fixed point.
72 citations
66 citations
TL;DR: In this paper, a renormalization group analysis of the E8 × E8 heterotic string and M-theory on Calabi-Yau manifolds with specific SU(4) vector bundles is presented.
Abstract: The matter spectrum of the MSSM, including three right-handed neutrino supermultiplets and one pair of Higgs–Higgs conjugate superfields, can be obtained by compactifying the E8 ×E8 heterotic string and M-theory on Calabi–Yau manifolds with specific SU(4) vector bundles. These theories have the standard model gauge group augmented by an additional gauged U(1)B-L. Their minimal content requires that the B-L gauge symmetry be spontaneously broken by a vacuum expectation value of at least one right-handed sneutrino. In previous papers, we presented the results of a quasianalytic renormalization group analysis showing that B-L gauge symmetry is indeed radiatively broken with an appropriate B-L/electroweak hierarchy. In this paper, we extend these results by (1) enlarging the initial parameter space and (2) explicitly calculating the renormalization group equations numerically. The regions of the initial parameter space leading to realistic vacua are presented and the B-L/electroweak hierarchy computed over these regimes. At representative points, the mass spectrum for all sparticles and Higgs fields is calculated and shown to be consistent with present experimental bounds. Some fundamental phenomenological signatures of a nonzero right-handed sneutrino expectation value are discussed, particularly the cosmology and proton lifetime arising from induced lepton and baryon number violating interactions.
60 citations
TL;DR: In this article, the first-order differential relations allowing one to obtain the associated exceptional orthogonal polynomials from those arising in a (k-1)thorder analysis are established.
Abstract: A previous study of exactly solvable rationally-extended radial oscillator potentials and corresponding Laguerre exceptional orthogonal polynomials carried out in second-order supersymmetric quantum mechanics is extended to kth-order one. The polynomial appearing in the potential denominator and its degree are determined. The first-order differential relations allowing one to obtain the associated exceptional orthogonal polynomials from those arising in a (k-1)th-order analysis are established. Some nontrivial identities connecting products of Laguerre polynomials are derived from shape invariance.
59 citations
TL;DR: In this paper, the authors consider rescaling with N massless fields and show that any curvature quantity takes a sufficiently small value without changing its causal structure, and that any fundamental resolution of the information loss problem should resolve the problem of the singularity.
Abstract: We consider semiclassical black holes and related rescalings with N massless fields. For a given semiclassical solution of an N = 1 universe, we can find other solution of a large N universe by the rescaling. After the rescaling, any curvature quantity takes a sufficiently small value without changing its causal structure. Via the rescaling, we argue that black hole complementarity for semiclassical black holes cannot provide a fundamental resolution of the information loss problem, and the violation of black hole complementarity requires sufficiently reasonable amounts of N. Such N might be realized from some string inspired models. Finally, we claim that any fundamental resolution of the information loss problem should resolve the problem of the singularity.
57 citations
TL;DR: In this article, the authors investigated the properties of κ-Minkowski space-time by using representations of the corresponding deformed algebra in terms of undeformed Heisenberg-Weyl algebra.
Abstract: We investigate the properties of κ-Minkowski space–time by using representations of the corresponding deformed algebra in terms of undeformed Heisenberg–Weyl algebra. The deformed algebra consists of κ-Poincare algebra extended with the generators of the deformed Weyl algebra. The part of deformed algebra, generated by rotation, boost and momentum generators, is described by the Hopf algebra structure. The approach used in our considerations is completely Lorentz covariant. We further use an advantage of this approach to consistently construct a star product, which has a property that under integration sign, it can be replaced by a standard pointwise multiplication, a property that was since known to hold for Moyal but not for κ-Minkowski space–time. This star product also has generalized trace and cyclic properties, and the construction alone is accomplished by considering a classical Dirac operator representation of deformed algebra and requiring it to be Hermitian. We find that the obtained star product is not translationally invariant, leading to a conclusion that the classical Dirac operator representation is the one where translation invariance cannot simultaneously be implemented along with hermiticity. However, due to the integral property satisfied by the star product, noncommutative free scalar field theory does not have a problem with translation symmetry breaking and can be shown to reduce to an ordinary free scalar field theory without nonlocal features and tachyonic modes and basically of the very same form. The issue of Lorentz invariance of the theory is also discussed.
55 citations
TL;DR: In this paper, Implicit Regularization (IReg) is proposed to become an invariant framework in momentum space to perform Feynman diagram calculations to arbitrary loop order, and a systematic implementation of IReg is presented that automatically displays the terms to be subtracted by Bogoliubov's recursion formula.
Abstract: Implicit Regularization (IReg) is a candidate to become an invariant framework in momentum space to perform Feynman diagram calculations to arbitrary loop order. In this work we present a systematic implementation of our method that automatically displays the terms to be subtracted by Bogoliubov's recursion formula. Therefore, we achieve a twofold objective: we show that the IReg program respects unitarity, locality and Lorentz invariance and we show that our method is consistent since we are able to display the divergent content of a multiloop amplitude in a well-defined set of basic divergent integrals in one-loop momentum only which is the essence of IReg. Moreover, we conjecture that momentum routing invariance in the loops, which has been shown to be connected with gauge symmetry, is a fundamental symmetry of any Feynman diagram in a renormalizable quantum field theory.
TL;DR: In this article, the generalized-CP transformations with Higgs-family transformations have been examined in the two-Higgs-doublet model and new results concerning those symmetries have been derived.
Abstract: In the two-Higgs-doublet model (THDM), generalized-CP transformations ( where X is unitary) and unitary Higgs-family transformations (φi→Uijφj) have recently been examined in a series of papers. In terms of gauge-invariant bilinear functions of the Higgs fields φi, the Higgs-family transformations and the generalized-CP transformations possess a simple geometric description. Namely, these transformations correspond in the space of scalar-field bilinears to proper and improper rotations, respectively. In this formalism, recent results relating generalized CP transformations with Higgs-family transformations have a clear geometric interpretation. We will review what is known regarding THDM symmetries, as well as derive new results concerning those symmetries, namely how they can be interpreted geometrically as applications of several CP transformations.
TL;DR: In this paper, Neyenhuis et al. investigated the possibility of detecting the Podolsky generalized electrodynamics constant a. In order to set up bounds for a, they investigated the influence of the electrostatic potential on the ground state of the Hydrogen atom.
Abstract: We investigate the possibility of detecting the Podolsky generalized electrodynamics constant a. First we analyze an ion interferometry apparatus proposed by B. Neyenhuis et al. ( Phys. Rev. Lett.99, 200401 (2007)), who looked for deviations from Coulomb's inverse-square law in the context of Proca model. Our results show that this experiment has not enough precision for measurements of a. In order to set up bounds for a, we investigate the influence of Podolsky's electrostatic potential on the ground state of the Hydrogen atom. The value of the ground state energy of the Hydrogen atom requires Podolsky's constant to be smaller than 5.6 fm, or in energy scales larger than 35.51 MeV.
TL;DR: In this article, the authors explain the motivations for soft leptogenesis, and review its basic ingredients: the different CP-violating contributions, the crucial role played by thermal corrections, and the enhancement of the efficiency from lepton flavor effects.
Abstract: Soft leptogenesis is a scenario in which the cosmic baryon asymmetry is produced from a lepton asymmetry generated in the decays of heavy sneutrinos (the partners of the singlet neutrinos of the seesaw) and where the relevant sources of CP violation are the complex phases of soft supersymmetry-breaking terms. We explain the motivations for soft leptogenesis, and review its basic ingredients: the different CP-violating contributions, the crucial role played by thermal corrections, and the enhancement of the efficiency from lepton flavor effects. We also discuss the high temperature regime T > 107GeV in which the cosmic baryon asymmetry originates from an initial asymmetry of an anomalous R-charge, and soft leptogenesis reembodies in R-genesis.
TL;DR: In this paper, the authors discuss the construction and some applications of such classes of theories, and the one-loop perturbative renormalization of the four-dimensional lattice SYM is discussed in particular.
Abstract: Inspired by the ideas from topological field theory it is possible to rewrite the supersymmetric charges of certain classes of extended supersymmetric Yang–Mills (SYM) theories in such a way that they are compatible with the discretization on a Euclidean space–time lattice. Such theories are known as maximally twisted SYM theories. In this review we discuss the construction and some applications of such classes of theories. The one-loop perturbative renormalization of the four-dimensional lattice SYM is discussed in particular. The lattice theories constructed using twisted approach play an important role in investigating the thermal phases of strongly coupled SYM theories and also the thermodynamic properties of their dual gravitational theories.
TL;DR: In this article, the authors extended these results by computing three-point correlation functions corresponding to a folded three-spin semiclassical string with one angular momentum in AdS and two equal spins in the sphere.
Abstract: Recently there has been progress on the calculation of n-point correlation functions with two "heavy" (with large quantum numbers) states at strong coupling. We extend these findings by computing three-point functions corresponding to a folded three-spin semiclassical string with one angular momentum in AdS and two equal spins in the sphere. We recover previous results as limiting cases. Also, following a recent paper by Buchbinder and Tseytlin, we provide relevant four-point functions and consider some of their limits.
TL;DR: In this article, the sign and peak magnitude of the nonlinearity parameter fNL related to generic features in the inflationary potential were investigated in multiple-field inflationary models.
Abstract: We study the evolution of non-Gaussianity in multiple-field inflationary models, focusing on three fundamental questions: (a) How is the sign and peak magnitude of the non-linearity parameter fNL related to generic features in the inflationary potential? (b) How sensitive is fNL to the process by which an adiabatic limit is reached, where the curvature perturbation becomes conserved? (c) For a given model, what is the appropriate tool – analytic or numerical – to calculate fNL at the adiabatic limit? We summarise recent results obtained by the authors and further elucidate them by considering an inflection point model.
TL;DR: In this article, a generalization of the description of gauge theories is applied to the case of Yang-Mills theories with gauge group SU(N) to consider especially the application to the electroweak theory as it appears in the Standard Model.
Abstract: According to the introduction of a minimal length to quantum field theory, which is directly related to a generalized uncertainty principle, the implementation of the gauge principle becomes much more intricated. It has been shown in another paper how gauge theories have to be extended in general, if there is assumed the existence of a minimal length. In this paper this generalization of the description of gauge theories is applied to the case of Yang–Mills theories with gauge group SU(N) to consider especially the application to the electroweak theory as it appears in the Standard Model. The modifications of the lepton-, Higgs- and gauge field sector of the extended Lagrangian of the electroweak theory maintaining local gauge invariance under SU(2)L ⊗ U(1)Y transformations are investigated. There appear additional interaction terms between the leptons or the Higgs particle respectively with the photon and the W- and Z-bosons as well as additional self-interaction terms of these gauge bosons themselves. It is remarkable that in the quark sector where the full gauge group of the Standard Model, SU(3)c ⊗ SU(2)L ⊗ U(1)Y, has to be considered there arise coupling terms between the gluons und the W- and Z-bosons which means that the electroweak theory is not separated from quantum chromodynamics anymore.
TL;DR: In this article, exact solutions of the Dirac equation with the pseudoharmonic potential including linear as well as Coulomb-like tensor potential with arbitrary spin-orbit coupling number κ under spin and pseudospin symmetry limits are presented.
Abstract: In this paper, we present exact solutions of the Dirac equation with the pseudoharmonic potential including linear as well as Coulomb-like tensor potential with arbitrary spin–orbit coupling number κ under spin and pseudospin symmetry limits. The Nikiforov–Uvarov method is used to obtain energy eigenvalues and corresponding eigenfunctions in closed forms. We show that tensor interaction removes degeneracies between spin and pseudospin doublets. Some numerical results are also given.
TL;DR: In this paper, the authors construct realizations of the generators of the κ-Minkowski space and the Hopf algebra as formal power series in the h-adic extension of the Weyl algebra.
Abstract: We construct realizations of the generators of the κ-Minkowski space and κ-Poincare algebra as formal power series in the h-adic extension of the Weyl algebra. The Hopf algebra structure of the κ-Poincare algebra related to different realizations is given. We construct realizations of the exterior derivative and one-forms, and define a differential calculus on κ-Minkowski space which is compatible with the action of the Lorentz algebra. In contrast to the conventional bicovariant calculus, the space of one-forms has the same dimension as the κ-Minkowski space.
TL;DR: In this article, the half-genus expansion of the resolvent function in the β-deformed matrix model with three-Penner potential under the AGT conjecture and the 0d-4d dictionary is considered.
Abstract: We consider the half-genus expansion of the resolvent function in the β-deformed matrix model with three-Penner potential under the AGT conjecture and the 0d–4d dictionary. The partition function of the model, after the specification of the paths, becomes the DF conformal block for fixed c and provides the Nekrasov partition function expanded both in and in ϵ = ϵ1+ϵ2. Exploiting the explicit expressions for the lower terms of the free energy extracted from the above expansion, we derive the first few ϵ corrections to the Seiberg–Witten prepotential in terms of the parameters of SU(2), Nf = 4, supersymmetric gauge theory.
TL;DR: In this paper, the authors review the importance of the holographic principle to encode nonlocal gravity features allowing us to relate the gravitational physics of local observers with thermodynamics and the role causality plays in these arguments by identifying horizons as diathermic walls.
Abstract: I review some of the concepts at the crossroads of gravitational thermodynamics, holography and quantum mechanics. First, the origin of gravitational thermodynamics due to coarse graining of quantum information is exemplified using the half-BPS sector of SYM and its LLM description in type IIB supergravity. The notion of black holes as effective geometries, its relation to the fuzzball programme and some of the puzzles raising for large black holes are discussed. Second, I review recent progress for extremal black holes, both microscopically, discussing a constituent model for stationary extremal non-BPS black holes, and semiclassically, discussing the extremal black hole/CFT conjecture. The latter is examined from the AdS3/CFT2 perspective. Third, I review the importance of the holographic principle to encode nonlocal gravity features allowing us to relate the gravitational physics of local observers with thermodynamics and the role causality plays in these arguments by identifying horizons (screens) as diathermic walls. I speculate with the emergence of an approximate CFT in the deep IR close to any horizon and its relation with an effective dynamical description of the degrees of freedom living on these holographic screens.
TL;DR: In this paper, it was shown that if the sum of two coherent Breit-Wigner functions is used to fit the measured distribution, there should be two and only two nontrivial solutions, and they are related to each other by analytical formulae.
Abstract: The recent multiple-solution problem in extracting physics information from a fit to the experimental data in high energy physics is reviewed from a mathematical viewpoint. All these multiple solutions were previously found via a fit process, while in this paper we prove that if the sum of two coherent Breit–Wigner functions is used to fit the measured distribution, there should be two and only two nontrivial solutions, and they are related to each other by analytical formulae. For real experimental measurements in more complicated situations, we also provide a numerical method to derive the other solution from the already obtained one. The excellent consistency between the exact solution obtained this way and the fit process justifies the method. From our results it is clear that the physics interpretation should be very different depending on which solution is selected. So we suggest that all the experimental measurements with potential multiple solutions be re-analyzed to find the other solution because the result is not complete if only one solution is reported.
TL;DR: In this article, a simple model for elastic diffractive hadron scattering, reproducing the dip-bump structure is used to analyze pp and scattering, and the role of the nonlinearity of the Regge trajectories is scrutinized.
Abstract: A simple model for elastic diffractive hadron scattering, reproducing the dip-bump structure is used to analyze pp and scattering. The main emphasis is on the delicate and nontrivial dynamics in the dip-bump region, near t = -1 GeV2. The simplicity of the model and the expected smallness of the absorption corrections enables one the control of various contributions to the scattering amplitude, in particular the interplay between the C-even and C-odd components of the amplitude, as well as their relative contribution, changing with s and t. The role of the nonlinearity of the Regge trajectories is scrutinized. The ratio of the real to imaginary parts of the forward amplitude, the ratio of elastic to total cross-sections and the inelastic cross-section are calculated. Predictions for the LHC energy region, where most of the existing models will be either confirmed or ruled out, are presented.
TL;DR: In this article, the cosmological constant in the context of the multiverse in Lorentzian space-time was studied, and it was shown that cosmologically constant will vanish in the future.
Abstract: We study the problem of the cosmological constant in the context of the multiverse in Lorentzian space–time, and show that the cosmological constant will vanish in the future. This sort of argument was started by Sidney Coleman in 1989, and he argued that the Euclidean wormholes make the multiverse partition function a superposition of various values of the cosmological constant Λ, which has a sharp peak at Λ = 0. However, the implication of the Euclidean analysis to our Lorentzian space–time is unclear. With this motivation, we analyze the quantum state of the multiverse in Lorentzian space–time by the WKB method, and calculate the density matrix of our universe by tracing out the other universes. Our result predicts vanishing cosmological constant. While Coleman obtained the enhancement at Λ = 0 through the action itself, in our Lorentzian analysis the similar enhancement arises from the front factor of eiS in the universe wave function, which is in the next leading order in the WKB approximation.
TL;DR: In this article, a new bottom-up holographic model was proposed to describe the Regge-like spectrum of mesons, which emerges due to condensation of a scalar field in the bulk anti-de Sitter space.
Abstract: We propose a new type of bottom-up holographic model describing the Regge-like spectrum of mesons. This type of spectrum emerges due to condensation of a scalar field in the bulk anti-de Sitter space. The gauge invariance of the action describing the vector mesons requires that the bulk scalar field must correspond to an operator of canonical dimension two. This is not necessary for the description of the scalar sector where the generation of the mass spectrum can be directly related to the formation of gluon condensate in QCD. It is also demonstrated that such an explicit introduction of local dimension-2 operator into the model leads to disappearance of the corresponding contribution from the dimension-2 condensate in the power expansion of the gauge-invariant vector correlator as required by QCD.
TL;DR: In this paper, Born's reciprocal general relativity theory in curved space-time was extended to the curved phase-space scenario, which requires the introduction of a complex Hermitian metric, torsion and nonmetricity.
Abstract: We explore some novel consequences of Born's reciprocal relativity theory in flat phase-space and generalize the theory to the curved space–time scenario. We provide, in particular, six specific results resulting from Born's reciprocal relativity and which are not present in special relativity. These are: momentum-dependent time delay in the emission and detection of photons; energy-dependent notion of locality; superluminal behavior; relative rotation of photon trajectories due to the aberration of light; invariance of areas-cells in phase-space and modified dispersion relations. We finalize by constructing a Born reciprocal general relativity theory in curved space–time which requires the introduction of a complex Hermitian metric, torsion and nonmetricity. The latter procedure can be extended to the curved phase-space scenario.
TL;DR: In this paper, the effects of bulk Maxwell field, an extra U (1) gauge field and probe D-branes on the DC conductivity, the DC Hall conductivity and the AC conductivity are extensively analyzed.
Abstract: We give a review on our recent work arXiv:1006.0779 [hep-th] and arXiv:1006.1719 [hep-th], in which properties of holographic strange metals were investigated. The background is chosen to be anisotropic scaling solution in Einstein-Maxwell-Dilaton theory with a Liouville potential. The effects of bulk Maxwell field, an extra U (1) gauge field and probe D-branes on the DC conductivity, the DC Hall conductivity and the AC conductivity are extensively analyzed. We classify behaviors of the conductivities according to the parameter ranges in the bulk theory and characterize conditions when the holographic results can reproduce experimental data.
TL;DR: In this article, a D-brane model of cosmology and space-time foam is proposed to explain variations in the D-particle density encountered at different cosmological epochs.
Abstract: In a D-brane model of cosmology and space–time foam, there are contributions to the dark energy that depend on the D-brane 10-velocities and on the density of D-particle defects in the ten-dimensional bulk. The latter may also reduce the speeds of energetic photons, establishing a phenomenological connection with astrophysical probes of the universality of the velocity of light. Specifically, the cosmological dark energy density measured at the present epoch may be linked to the apparent retardation of energetic photons propagating from nearby AGN's. However, this nascent field of "D-foam phenomenology" may be complicated by variations in the D-particle density encountered at different cosmological epochs. A reduced density of D-particles encountered at redshifts z ~ 1 — a "D-void" — would increase the dark energy while suppressing the vacuum refractive index, and thereby might reconcile the AGN measurements with the relatively small retardation seen for the energetic photons propagating from GRB 090510, as measured by the Fermi satellite.
TL;DR: In this paper, the second-order corrections in the noncommutativity parameter of the Klein-Gordon equation were investigated and shown to be the source of the Lamb shift corrections.
Abstract: We improve the previous study of the Klein–Gordon equation in a noncommutative space–time as applied to the hydrogen atom to extract the energy levels, by considering the second-order corrections in the noncommutativity parameter. Phenomenologically we show that noncommutativity is the source of Lamb shift corrections.