Showing papers in "International Journal of Modern Physics A in 2016"
TL;DR: In this paper, it was shown that the construction of fermionic Symmetry Protected Topological orders has a hidden dependence on a discrete spin structure on the Euclidean space-time.
Abstract: We study lattice constructions of gapped fermionic phases of matter. We show that the construction of fermionic Symmetry Protected Topological orders by Gu and Wen has a hidden dependence on a discrete spin structure on the Euclidean space-time. The spin structure is needed to resolve ambiguities which are otherwise present. An identical ambiguity is shown to arise in the fermionic analog of the string-net construction of 2D topological orders. We argue that the need for a spin structure is a general feature of lattice models with local fermionic degrees of freedom and is a lattice analog of the spin-statistics relation.
173 citations
TL;DR: In this paper, the authors review models of new physics in which dark matter arises as a composite bound state from a confining strongly-coupled non-Abelian gauge theory.
Abstract: We review models of new physics in which dark matter arises as a composite bound state from a confining strongly-coupled non-Abelian gauge theory. We discuss several qualitatively distinct classes of composite candidates, including dark mesons, dark baryons, and dark glueballs. We highlight some of the promising strategies for direct detection, especially through dark moments, using the symmetries and properties of the composite description to identify the operators that dominate the interactions of dark matter with matter, as well as dark matter self-interactions. We briefly discuss the implications of these theories at colliders, especially the (potentially novel) phenomenology of dark mesons in various regimes of the models. Throughout the review, we highlight the use of lattice calculations in the study of these strongly-coupled theories, to obtain precise quantitative predictions and new insights into the dynamics.
148 citations
TL;DR: In this article, the authors build unitary representations of the BMS algebra and its higher-spin extensions in three dimensions using induced representations as a guide, which naturally emerges from an ultra-relativistic limit of highest-weight representations of Virasoro and 𝒲 algebras.
Abstract: We build unitary representations of the BMS algebra and its higher-spin extensions in three dimensions, using induced representations as a guide. Our prescription naturally emerges from an ultrarelativistic limit of highest-weight representations of Virasoro and 𝒲 algebras, which is to be contrasted with nonrelativistic limits that typically give nonunitary representations. To support this dichotomy, we also point out that the ultrarelativistic and nonrelativistic limits of generic 𝒲 algebras differ in the structure of their nonlinear terms.
86 citations
TL;DR: In this article, the sign problem in lattice field theories is reviewed, focusing on two more recent methods: dualization to worldline type of representations and the density-of-states approach.
Abstract: Quantum field theories (QFTs) at finite densities of matter generically involve complex actions. Standard Monte Carlo simulations based upon importance sampling, which have been producing quantitative first principle results in particle physics for almost forty years, cannot be applied in this case. Various strategies to overcome this so-called sign problem or complex action problem were proposed during the last thirty years. We here review the sign problem in lattice field theories, focusing on two more recent methods: dualization to worldline type of representations and the density-of-states approach.
74 citations
TL;DR: In this paper, it has been shown that the overall fit to the cosmological observables SNIa+BAO+H(z)+LSS+BBN+CMB do favor the class of running vacuum models (RVM's) against the "concordance" ΛCDM model.
Abstract: Next year we will celebrate 100 years of the cosmological term, Λ, in Einstein’s gravitational field equations, also 50 years since the cosmological constant problem was first formulated by Zeldovich, and almost about two decades of the observational evidence that a nonvanishing, positive, Λ-term could be the simplest phenomenological explanation for the observed acceleration of the Universe. This mixed state of affairs already shows that we do no currently understand the theoretical nature of Λ. In particular, we are still facing the crucial question whether Λ is truly a fundamental constant or a mildly evolving dynamical variable. At this point the matter should be settled once more empirically and, amazingly enough, the wealth of observational data at our disposal can presently shed true light on it. In this short review, I summarize the situation of some of these studies. It turns out that the Λ = const. hypothesis, despite being the simplest, may well not be the most favored one when we put it in hard-fought competition with specific dynamical models of the vacuum energy. Recently, it has been shown that the overall fit to the cosmological observables SNIa+BAO+H(z)+LSS+BBN+CMB do favor the class of “running” vacuum models (RVM’s) — in which Λ = Λ(H) is a function of the Hubble rate — against the “concordance” ΛCDM model. The support is at an unprecedented level of ∼ 4σ and is backed up with Akaike and Bayesian criteria leading to compelling evidence in favor of the RVM option and other related dynamical vacuum models. I also address the implications of this framework on the possible time evolution of the fundamental constants of Nature.
64 citations
TL;DR: In this article, the authors studied the covariant Duffin-kemmer-petiau (DKP) equation in the cosmic string space-time and considered the interaction of a DKP field with the gravitational field produced by topological defects in order to examine the influence of topology on this system.
Abstract: In this paper, we study the covariant Duffin-Kemmer-Petiau (DKP) equation in the cosmic-string space-time and consider the interaction of a DKP field with the gravitational field produced by topological defects in order to examine the influence of topology on this system. We solve the spin-zero DKP oscillator in the presence of the Cornell interaction with a rotating coordinate system in an exact analytical manner for nodeless and one-node states by proposing a proper ansatz solution.
57 citations
TL;DR: The three-loop ladder diagram is a graph with six links and four cubic vertices that contributes to the D12ℛ4 amplitude at genus one in type II string theory as mentioned in this paper.
Abstract: The three-loop ladder diagram is a graph with six links and four cubic vertices that contributes to the D12ℛ4 amplitude at genus one in type II string theory. The vertices represent the insertion points of vertex operators on the toroidal worldsheet and the links represent scalar Green functions connecting them. By using the properties of the Green function and manipulating the various expressions, we obtain a modular invariant Poisson equation satisfied by this diagram, with source terms involving one-, two- and three-loop diagrams. Unlike the source terms in the Poisson equations for diagrams at lower orders in the momentum expansion or the Mercedes diagram, a particular source term involves a five-point function containing a holomorphic and a antiholomorphic worldsheet derivative acting on different Green functions. We also obtain simple equalities between topologically distinct diagrams, and consider some elementary examples.
49 citations
TL;DR: In this article, the canonical, path-integral, Weyl-Wigner and systematic formulations of quantum mechanics on noncommutative Moyal phase spaces are reviewed.
Abstract: Four formulations of quantum mechanics on noncommutative Moyal phase spaces are reviewed. These are the canonical, path-integral, Weyl–Wigner and systematic formulations. Although all these formulations represent quantum mechanics on a phase space with the same deformed Heisenberg algebra, there are mathematical and conceptual differences which we discuss.
49 citations
TL;DR: In this paper, the spectral sum rule (QSSR) was used to predict the masses of the BK molecule and four-quark states, and the results were improved by adding NLO and N2LO corrections to the PT contributions giving a more precise meaning on the b-quarks mass definition used in the analysis.
Abstract: We scrutinize recent QCD spectral sum rules (QSSR) results to lowest order (LO) predicting the masses of the BK molecule and (su)(bd¯) four-quark states. We improve these results by adding NLO and N2LO corrections to the PT contributions giving a more precise meaning on the b-quark mass definition used in the analysis. We extract our optimal predictions using Laplace sum rule (LSR) within the standard stability criteria versus the changes of the external free parameters (τ-sum rule variable, tc continuum threshold and subtraction constant μ). The smallness of the higher order PT corrections justifies (a posteriori) the LO order results ⊕ the uses of the ambiguous heavy quark mass to that order. However, our predicted spectra in the range (5173 ∼ 5226) MeV, summarized in Table 7, for exotic hadrons built with four different flavors (buds), do not support some previous interpretations of the D0 candidate,1 X(5568), as a pure molecule or a four-quark state. If experimentally confirmed, it could result from their mixing with an angle: sin 2𝜃 ≈ 0.15. One can also scan the region (2327 ∼ 2444) MeV (where the Ds0∗(2317) might be a good candidate) and the one (5173 ∼ 5226) MeV for detecting these (cuds) and (buds) unmixed exotic hadrons (if any) via, eventually, their radiative or π+hadrons decays.
43 citations
TL;DR: In this article, the compatibility of the unified left-right symmetric Pati-Salam models motivated by noncommutative geometry and the TeV-scale right-handed W boson suggested by recent LHC data was analyzed.
Abstract: We analyze the compatibility of the unified left–right symmetric Pati–Salam models motivated by noncommutative geometry and the TeV-scale right-handed W boson suggested by recent LHC data. We find that the unification/matching conditions place conflicting demands on the symmetry breaking scales and that generating the required WR mass and coupling is nontrivial.
42 citations
TL;DR: In this paper, the authors review the theoretical foundations of the effective string theory for confining flux tubes and the comparison of the predictions to pure gauge lattice data. And they summarize the predictions for the spectrum and the profile/width of the flux tube.
Abstract: We review the current knowledge about the theoretical foundations of the effective string theory for confining flux tubes and the comparison of the predictions to pure gauge lattice data. A concise presentation of the effective string theory is provided, incorporating recent developments. We summarize the predictions for the spectrum and the profile/width of the flux tube and their comparison to lattice data. The review closes with a short summary of open questions for future research.
TL;DR: In this paper, the authors study the multiscalar-tensor theories of gravity without derivative couplings and construct a few basic objects that are invariant under a Weyl rescaling of the metric and transform covariantly when the scalar fields are redefined.
Abstract: The aim of the current paper is to study the multiscalar-tensor theories of gravity without derivative couplings. We construct a few basic objects that are invariant under a Weyl rescaling of the metric and transform covariantly when the scalar fields are redefined. We introduce rules to construct further such objects and put forward a scheme that allows to express the results obtained either in the Einstein frame or in the Jordan frame as general ones. These so-called “translation” rules are used to show that the parametrized post-Newtonian approximation results obtained in the aforementioned two frames indeed are the same if expressed in a general frame.
TL;DR: In this paper, the authors present new compact integrated expressions of QCD spectral functions of heavy-light molecules and four-quark XY Z-like states at lowest order (LO) of perturbative (PT) QCD and up to d = 8 condensates of the Operator Product Expansion (OPE).
Abstract: We present new compact integrated expressions of QCD spectral functions of heavy-light molecules and four-quark XY Z-like states at lowest order (LO) of perturbative (PT) QCD and up to d = 8 condensates of the Operator Product Expansion (OPE). Then, by including up to next-to-next leading order (N2LO) PT QCD corrections, which we have estimated by assuming the factorization of the four-quark spectral functions, we improve previous LO results from QCD spectral sum rules (QSSR), on the XY Z-like masses and decay constants which suffer from the ill-defined heavy quark mass. PT N3LO corrections are estimated using a geometric growth of the PT series and are included in the systematic errors. Our optimal results based on stability criteria are summarized in Tables 11–14 and compared, in Sec. 10, with experimental candidates and some LO QSSR results. We conclude that the masses of the XZ observed states are compatible with (almost) pure JPC = 1+±, 0++ molecule or/and four-quark states. The ones of the 1−±, 0−± ...
TL;DR: In this article, the authors review recent progress in the lattice investigations of near-conformal non-Abelian gauge theories relevant for dynamical symmetry breaking and model building of composite Higgs models.
Abstract: We review recent progress in the lattice investigations of near-conformal non-Abelian gauge theories relevant for dynamical symmetry breaking and model building of composite Higgs models. The emphasis is placed on the mass spectrum and the running renormalized coupling. The role of a light composite scalar isosinglet particle as a composite Higgs particle is highlighted.
TL;DR: In this article, it was shown that using dipolar quantization instead of radial quantization leads to a continuous and strongly degenerated spectrum in addition to the Virasoro algebra with a continuous index.
Abstract: Elaborating on our previous presentation, where the term dipolar quantization was introduced, we argue here that adopting L0 − (L1 + L−1)/2 + L0 − (L1 + L−1)/2 as the Hamiltonian instead of L0 + L0 yields an infinite circumference limit in two-dimensional conformal field theory. The new Hamiltonian leads to dipolar quantization instead of radial quantization. As a result, the new theory exhibits a continuous and strongly degenerated spectrum in addition to the Virasoro algebra with a continuous index. Its Hilbert space exhibits a different inner product than that obtained in the original theory. The idiosyncrasy of this particular Hamiltonian is its relation to the so-called sine-square deformation, which is found in the study of a certain class of quantum statistical systems. The appearance of the infinite circumference explains why the vacuum states of sine-square deformed systems are coincident with those of the respective closed-boundary systems.
TL;DR: In this paper, the authors argue that the correction to the Higgs mass coming from the bound state of 6 top and 6 antitop quarks, predicted early by Froggatt and ourselves, leads to the Standard Model vacuum stability and confirms the accuracy of the multiple point principle (principle of degenerate vacua) for all experimentally valued parameters (Higgs mass, top-quark mass, etc.).
Abstract: In the present paper we argue that the correction to the Higgs mass coming from the bound state of 6 top and 6 antitop quarks, predicted early by Froggatt and ourselves, leads to the Standard Model vacuum stability and confirms the accuracy of the multiple point principle (principle of degenerate vacua) for all experimentally valued parameters (Higgs mass, top-quark mass, etc.). Fitting to get the vacuum degeneracy requires a mass of the bound state, just in the region of the new two photon state in Large Hadron Collider, 750–760 GeV.
TL;DR: In this paper, a model of nonlinear electromagnetic fields with a dimensional parameter β was proposed and the bound on the parameter β is obtained from PVLAS experiment and the range of the scale factor, when the causality of the model and a classical stability take place, was obtained, in approximate agreement with the Planck, WMAP, and BICEP2 data.
Abstract: A model of nonlinear electromagnetic fields with a dimensional parameter β is proposed. From PVLAS experiment the bound on the parameter β was obtained. Electromagnetic fields are coupled with the gravitation field and we show that the universe accelerates due to nonlinear electromagnetic fields. The magnetic universe is considered and the stochastic magnetic field is a background. After inflation the universe decelerates and approaches to the radiation era. The range of the scale factor, when the causality of the model and a classical stability take place, was obtained. The spectral index, the tensor-to-scalar ratio, and the running of the spectral index were estimated which are in approximate agreement with the Planck, WMAP, and BICEP2 data.
TL;DR: In this paper, the authors discuss the motivations, difficulties and progress in the study of supersymmetric lattice gauge theories focusing in particular on 𝒩 = 1 and +#x 1d4b4b8; = 4 super-Yang-Mills in four dimensions.
Abstract: We discuss the motivations, difficulties and progress in the study of supersymmetric lattice gauge theories focusing in particular on 𝒩 = 1 and 𝒩 = 4 super-Yang–Mills in four dimensions. Brief reviews of the corresponding lattice formalisms are given and current results are presented and discussed. We conclude with a summary of the main aspects of current work and prospects for the future.
TL;DR: In this paper, the mass spectrum and couplings of non-SM-like Higgs bosons were revisited to identify the relevant parameter space and the discovery potential of these non-sm-like bosons was guided by their couplings with gauge bosons and fermions.
Abstract: The next-to-minimal supersymmetric Standard Model (NMSSM) with an extended Higgs sector offers at least one Higgs boson as the Standard Model (SM)-like Higgs with a mass around 125 GeV. In this work, we revisit the mass spectrum and couplings of non-SM-like Higgs bosons taking into consideration most relevant constraints and identify the relevant parameter space. The discovery potential of these non-SM-like Higgs bosons, apart from their masses, is guided by their couplings with gauge bosons and fermions which are very much parameter space sensitive. We evaluate the rates of productions of these non-SM-like Higgs bosons at the LHC for a variety of decay channels in the allowed region of the parameter space. Although bb, ττ modes appear to be the most promising decay channels, but for a substantial region of parameter space the two-photon decay mode has a remarkably large rate. In this study we emphasize that this diphoton mode can be exploited to find the non-SM-like Higgs bosons of the NMSSM and can als...
TL;DR: In this paper, a nonlinear realisation based on the Kac-Moody algebra E11 and its vector representation is constructed, which is the low energy effective action for type II strings and branes.
Abstract: I begin with some memories of Abdus Salam who was my PhD supervisor. After reviewing the theory of nonlinear realisations and Kac–Moody algebras, I explain how to construct the nonlinear realisation based on the Kac–Moody algebra E11 and its vector representation. I explain how this field theory leads to dynamical equations which contain an infinite number of fields defined on a space–time with an infinite number of coordinates. I then show that these unique dynamical equations, when truncated to low level fields and the usual coordinates of space–time, lead to precisely the equations of motion of 11-dimensional supergravity theory. By taking different group decompositions of E11 we find all the maximal supergravity theories, including the gauged maximal supergravities, and as a result the nonlinear realisation should be thought of as a unified theory that is the low energy effective action for type II strings and branes. These results essentially confirm the E11 conjecture given many years ago.
TL;DR: In this article, the U(1)B−L gauge boson was investigated in a wide mass range mZ′≈ 0 −1012eV and the constraints on its coupling from various experiments were investigated.
Abstract: There is a growing interest for the search of new light gauge bosons. The small mass of a new boson can turn various kinds of low-energy experiments to a new discovery machine, depending on their couplings to the Standard Model particles. It is important to understand the properties of each type of gauge boson and their current constraints for a given mass. While the dark photon (which couples to the electric charges) and the U(1)B−L gauge boson have been well studied in an extensive mass range, the U(1)L gauge boson has not been fully investigated yet. We consider the gauge boson of the U(1)L in a wide mass range mZ′≈ 0–1012eV and investigate the constraints on its coupling from various experiments, discussing the similarities and differences from the dark photon and the U(1)B−L gauge boson.
TL;DR: In this article, a supersymmetric light-front Hamiltonian for hadrons composed of light quarks can be constructed by embedding superconformal quantum mechanics into AdS space.
Abstract: Superconformal algebra leads to remarkable connections between the masses of mesons and baryons of the same parity — supersymmetric relations between the bosonic and fermionic bound states of QCD. Supercharges connect the mesonic eigenstates to their baryonic superpartners, where the mesons have internal angular momentum one unit higher than the baryons: LM = LB + 1. The dynamics of the superpartner hadrons also match; for example, the power-law fall-off of the form factors are the same for the mesonic and baryonic superpartners, in agreement with twist counting rules. An effective supersymmetric light-front Hamiltonian for hadrons composed of light quarks can be constructed by embedding superconformal quantum mechanics into AdS space. This procedure also generates a spin–spin interaction between the hadronic constituents. A specific breaking of conformal symmetry inside the graded algebra determines a unique quark-confining light-front potential for light hadrons in agreement with the soft-wall AdS/QCD approach and light-front holography. Only one mass parameter λ appears; it sets the confinement mass scale, a universal value for the slope of all Regge trajectories, the nonzero mass of the proton and other hadrons in the chiral limit, as well as the length scale which underlies their structure. The mass for the pion eigenstate vanishes in the chiral limit. When one includes the constituent quark masses using the Feynman–Hellman theorem, the predictions are consistent with the empirical features of the light-quark hadronic spectra. Our analysis can be consistently applied to the excitation spectra of the π, ρ, K, K∗ and ϕ meson families as well as to the N, Δ, Λ, Σ, Σ∗, Ξ and Ξ∗ baryons. We also predict the existence of tetraquarks which are degenerate in mass with baryons with the same angular momentum. The mass-squared of the light hadrons can be expressed in a universal and frame-independent decomposition of contributions from the constituent kinetic energy, the confinement potential, and spin–spin contributions. We also predict features of hadron dynamics, including hadronic light-front wave functions, distribution amplitudes, form factors, valence structure functions and vector meson electroproduction phenomenology. The mass scale λ can be connected to the parameter ΛMS¯ in the QCD running coupling by matching the nonperturbative dynamics, as described by the light-front holographic approach to the perturbative QCD regime. The result is an effective coupling defined at all momenta. The matching of the high and low momentum-transfer regimes determines a scale Q0 proportional to λ which sets the interface between perturbative and nonperturbative hadron dynamics. The use of Q0 to resolve the factorization scale uncertainty for structure functions and distribution amplitudes, in combination with the scheme-independent Principle of Maximal Conformality (PMC) procedure for setting renormalization scales, can greatly improve the precision of perturbative QCD predictions.
TL;DR: In this article, the authors studied the quantum modifications of the Reissner-Nordstrom-(A)dS black hole within Quantum Einstein Gravity coupled to an electromagnetic sector, where the originally constant couplings were promoted to scale dependent quantities (Gk, Λk and αk).
Abstract: This paper studies the quantum modifications of the Reissner–Nordstrom–(A)dS black hole within Quantum Einstein Gravity, coupled to an electromagnetic sector. Quantum effects are introduced on the level of the improvements of the classical solution, where the originally constant couplings (G0, Λ0 and α0) are promoted to scale dependent quantities (Gk, Λk and αk). Those running couplings are calculated in the functional renormalization group approach. A crucial point of this so-called “improving solutions” procedure is the scale setting where the arbitrary scale k acquires physical meaning due to a relation to the coordinate scale r. It is proposed to use such scale settings which are stable after iterative improvements. Using this method one finds that for those improved solutions, there is no stable remnant and due to the appearance of a new internal horizon, there is also no necessity to impose a minimal black hole mass for charged black holes, in order to avoid the cosmic censorship hypothesis.
TL;DR: In this paper, the grand canonical potential of SU(3) Polyakov linear-σ model (PLSM) is analyzed for chiral phase transition, σl and σs and for deconfinement order-parameters, ϕ and ϕ∗ of light and strange quarks, respectively.
Abstract: In mean field approximation, the grand canonical potential of SU(3) Polyakov linear-σ model (PLSM) is analyzed for chiral phase transition, σl and σs and for deconfinement order-parameters, ϕ and ϕ∗ of light- and strange-quarks, respectively. Various PLSM parameters are determined from the assumption of global minimization of the real part of the potential. Then, we have calculated the subtracted condensates (Δl,s). All these results are compared with recent lattice QCD simulations. Accordingly, essential PLSM parameters are determined. The modeling of the relaxation time is utilized in estimating the conductivity properties of the QCD matter in thermal medium, namely electric [σel(T)] and heat [κ(T)] conductivities. We found that the PLSM results on the electric conductivity and on the specific heat agree well with the available lattice QCD calculations. Also, we have calculated bulk and shear viscosities normalized to the thermal entropy, ξ/s and η/s, respectively, and compared them with recent lattice QCD. Predictions for (ξ/s)/(σel/T) and (η/s)/(σel/T) are introduced. We conclude that our results on various transport properties show some essential ingredients, that these properties likely come up with, in studying QCD matter in thermal and dense medium.
TL;DR: In this paper, the authors investigated the lightest scalar baryon-like (T-baryon) state B0 = UD with mass mB ≳ 1TeV predicted by the simplest two-flavor vector-like confinement model as a dark matter (DM) candidate.
Abstract: A toy-model with SU(2)TC dynamics confined at high scales ΛTC ≫ 100GeV enables to construct Dirac UV completion from the original chiral multiplets predicting a vector-like nature of their weak interactions consistent with electroweak precision tests. In this work, we investigate a potential of the lightest scalar baryon-like (T-baryon) state B0 = UD with mass mB ≳ 1TeV predicted by the simplest two-flavor vector-like confinement model as a dark matter (DM) candidate. We show that two different scenarios with the T-baryon relic abundance formation before and after the electroweak (EW) phase transition epoch lead to symmetric (or mixed) and asymmetric DM, respectively. Such a DM candidate evades existing direct DM detection constraints since its vector coupling to Z boson absents at tree level, while one-loop gauge boson mediated contribution is shown to be vanishingly small close to the threshold. The dominating spin-independent (SI) T-baryon–nucleon scattering goes via tree-level Higgs boson exchange in the t-channel. The corresponding bound on the effective T-baryon–Higgs coupling has been extracted from the recent LUX data and turns out to be consistent with naive expectations from the light technipion case mπ ≪ ΛTC. The latter provides the most stringent phenomenological constraint on strongly-coupled SU(2)TC dynamics so far. Future prospects for direct and indirect scalar T-baryon DM searches in astrophysics as well as in collider measurements have been discussed.
TL;DR: In this article, a two-loop induced radiative neutrino model at TeV scale with global U(1) symmetry was studied, in which dark matter and resonant leptogenesis were analyzed.
Abstract: In this paper, we study a two-loop induced radiative neutrino model at TeV scale with global U(1) symmetry, in which we analyze dark matter and resonant leptogenesis. The model includes two kinds of dark matter candidates. We discuss what kind of dark matter can satisfy the observed relic density as well as the current direct detection bound, and be simultaneously compatible with the leptogenesis. We also discuss whether our resonant leptogenesis can be differentiated from the other scenarios at TeV scale or not.
TL;DR: In this article, the authors extend the class of finite BRST-anti-BRST transformations with odd-valued parameters to the case of functionally-dependent parameters, and show the equivalence of path integrals in any 3-parameter Rξ-like gauge.
Abstract: We continue our research1–4 and extend the class of finite BRST–anti-BRST transformations with odd-valued parameters λa, a = 1, 2, introduced in these works. In doing so, we evaluate the Jacobians induced by finite BRST–anti-BRST transformations linear in functionally-dependent parameters, as well as those induced by finite BRST–anti-BRST transformations with arbitrary functional parameters. The calculations cover the cases of gauge theories with a closed algebra, dynamical systems with first-class constraints, and general gauge theories. The resulting Jacobians in the case of linearized transformations are different from those in the case of polynomial dependence on the parameters. Finite BRST–anti-BRST transformations with arbitrary parameters induce an extra contribution to the quantum action, which cannot be absorbed into a change of the gauge. These transformations include an extended case of functionally-dependent parameters that implies a modified compensation equation, which admits nontrivial solutions leading to a Jacobian equal to unity. Finite BRST–anti-BRST transformations with functionally-dependent parameters are applied to the Standard Model, and an explicit form of functionally-dependent parameters λa is obtained, providing the equivalence of path integrals in any 3-parameter Rξ-like gauges. The Gribov–Zwanziger theory is extended to the case of the Standard Model, and a form of the Gribov horizon functional is suggested in the Landau gauge, as well as in Rξ-like gauges, in a gauge-independent way using field-dependent BRST–anti-BRST transformations, and in Rξ-like gauges using transverse-like non-Abelian gauge fields.
TL;DR: In this paper, the formation of nonperturbative classical configurations, called classicalons, in scatterings like ϕ → ϕϕ, can avoid typical acausal divergences.
Abstract: We suggest that classicalization can cure nonlocal quantum field theories from acausal divergences in scattering amplitudes, restoring unitarity and causality. In particular, in “trans-nonlocal” limit, the formation of nonperturbative classical configurations, called classicalons, in scatterings like ϕϕ → ϕϕ, can avoid typical acausal divergences.
TL;DR: In this article, the Minimal Unitarity Violation (MUV) scheme, an effective field theory framework which represents the class of extensions of the Standard Model (SM) by heavy neutral leptons, is discussed.
Abstract: The nonunitarity of the leptonic mixing matrix is a generic signal of new physics aiming at the generation of the observed neutrino masses. We discuss the Minimal Unitarity Violation (MUV) scheme, an effective field theory framework which represents the class of extensions of the Standard Model (SM) by heavy neutral leptons, and discuss the present bounds on the nonunitarity parameters as well as estimates for the sensitivity of the CEPC, based on the performance parameters from the preCDR.
CERN1
TL;DR: In this article, the authors review models of inflation based on Supergravity with spontaneously broken local supersymmetry, with emphasis on the role of nilpotent superfields to describe a de Sitter phase of our universe.
Abstract: Abdus Salam was a true master of 20th Century Theoretical Physics. Not only was he a pioneer of the Standard Model (for which he shared the Nobel Prize with S. Glashow and S. Weinberg), but he also (co)authored many other outstanding contributions to the field of Fundamental Interactions and their unification. In particular, he was a major contributor to the development of supersymmetric theories, where he also coined the word Supersymmetry (replacing the earlier “Supergauges” drawn from String Theory). He also introduced the basic concept of “Superspace” and the notion of “Goldstone Fermion”(Goldstino). These concepts proved instrumental for the exploration of the ultraviolet properties and for the study of spontaneously broken phases of super YangMills theories and Supergravity. They continue to play a key role in current developments in Early-Universe Cosmology. In this contribution we review models of inflation based on Supergravity with spontaneously broken local supersymmetry, with emphasis on the role of nilpotent superfields to describe a de Sitter phase of our Universe.