For explaining the AMS-02 cosmic positron excess, which was recently reported, we consider a scenario of thermally produced and decaying dark matter (DM) into the standard model (SM) leptons with an extremely small decay rate, ${\mathrm{\Gamma }}_{\mathrm{DM}}\sim {10}^{-26}{\sec }^{-1}$. Since the needed DM mass is relatively heavy ($700\mathrm{GeV}\lesssim m_{\mathrm{DM}}\lesssim 3000\mathrm{GeV}$), we introduce another DM component apart from the lightest supersymmetric particle (LSP). For its (meta-)stability and annihilation into other particles, the new DM should be accompanied with another $Z_2$ symmetry apart from the $R$ parity. Sizable renormalizable couplings of the new DM with SM particles, which are necessary for its thermalization in the early universe, cannot destabilize the new DM because of the new $Z_2$ symmetry. Since the new DM was thermally produced, it can naturally explain the present energy density of the Universe. The new DM can decay into the SM leptons (and the lightest supersymmetric particle) only through nonrenormalizable operators suppressed by a superheavy squared mass parameter after the new $Z_2$ symmetry is broken around TeV scale. We realize this scenario in a model of “gauged vectorlike leptons,” which was proposed recently for the naturalness of the Higgs boson.

A second Higgs doublet arises naturally as a parity partner of the standard model (SM) Higgs, once the SM is extended to its left-right symmetric version (LRSM) to understand the origin of parity violation in weak interactions, as well as to accommodate small neutrino masses via the seesaw mechanism. The flavor-changing neutral Higgs (FCNH) effects in the minimal version of this model (LRSM), however, push the second Higgs mass to more than 15 TeV, making it inaccessible at the LHC. Furthermore, since the second Higgs mass is directly linked to the $W_R$ mass, discovery of a “low” mass $W_R$ ($M_{W_R}\le 5–6\mathrm{TeV}$) at the LHC would require values for some Higgs self-couplings larger than 1. In this paper we present an extension of LRSM by adding a vectorlike $SU(2{)}_R$ quark doublet which weakens the FCNH constraints, allowing the second Higgs mass to be near or below the TeV range and a third neutral Higgs below 3 TeV for a $W_R$ mass below 5 TeV. It is then possible to search for these heavier Higgs bosons at the LHC without conflicting with FCNH constraints. A right-handed $W_R$ mass in the few TeV range is quite natural in this class of models without having to resort to large scalar coupling parameters. The CKM mixings are intimately linked to the vectorlike quark mixings with the known quarks, which is the main reason why the constraints on the second Higgs mass are relaxed. We present a detailed theoretical and phenomenological analysis of this extended left-right model and point out some tests as well as its potential for discovery of a second Higgs at the LHC. Two additional features of the model are a $5/3$-charged quark and a fermionic top partner with masses in the TeV range.

Confinement in asymptotically free gauge theories is accompanied by the spontaneous breaking of the global flavor symmetry. If a subgroup of the flavor symmetry group is coupled weakly to additional gauge fields, the vacuum state tends to align such that the gauged subgroup is unbroken. Independently, a lattice discretization of the continuum theory typically reduces the manifest flavor symmetry, and, in addition, can give rise to new lattice-artifact phases with spontaneously broken symmetries. Here, we study the interplay of these two phenomena for Wilson fermions, using chiral Lagrangian techniques. We consider two examples: electromagnetic corrections to QCD, and a prototype composite Higgs model.

We introduce a model of free harmonic oscillators that requires renormalization. The model is similar to but simpler than the soluble Lee model. We introduce two concrete examples: the first, resembling the three dimensional ${\varphi }^4$ theory, needs only mass renormalization, and the second, resembling the four dimensional ${\varphi }^4$ theory and the Lee model, needs additional renormalization of a coupling and a wave function.

We study the scattering amplitudes of mass-deformed Chern-Simons theories and Yang-Mills-Chern-Simons theories with $\mathcal{N}=2$ supersymmetry in three dimensions. In particular, we derive the on-shell supersymmetry algebras which underlie the scattering matrices of these theories. We then compute various 3 and 4-point on-shell tree-level amplitudes in these theories. For the mass-deformed Chern-Simons theory, odd-point amplitudes vanish and we find that all of the 4-point amplitudes can be encoded elegantly in superamplitudes. For the Yang-Mills-Chern-Simons theory, we obtain all of the 4-point tree-level amplitudes using a combination of perturbative techniques and algebraic constraints and we comment on difficulties related to computing amplitudes with external gauge fields using Feynman diagrams. Finally, we propose a Britto-Cachazo-Feng-Witten recursion relation for mass-deformed theories in three dimensions and discuss the applicability of this proposal to mass-deformed $\mathcal{N}=2$ theories.

We focus on the evolution of curvature perturbation on superhorizon scales by adopting the spatial gradient expansion and show that the nonlinear theory, called the beyond $\delta N$ formalism as the next-leading order in the expansion. As one application of our formalism for a single scalar field, we investigate the case of varying sound speed. In our formalism, we can deal with the time evolution in contrast to $\delta N$ formalism, where curvature perturbations remain just constant, and nonlinear curvature perturbation follows the simple master equation whose form is similar to one in linear theory. So the calculation of bispectrum can be done in the next-leading order in the expansion as similar as the case of deriving the power spectrum. We discuss localized features of both primordial power and bispectrum generated by the effect of varying sound speed with a finite duration time. We can see a local feature like a bump in the equilateral bispectrum.

We point out that the ability of some models of inflation, such as the Higgs inflation and the universal attractor models at large values of the coupling $\xi$, in reproducing the available data is due to their relation to the Starobinsky model of inflation. For large field values, where the inflationary phase takes place, all of these classes of models are indeed identical to the Starobinsky model. Nevertheless, the inflation is just an auxiliary field in the Jordan frame of the Starobinsky model, and this leads to two important consequences: first, the inflationary predictions of the Starobinsky model and its descendants are slightly different (albeit not measurably); second, the theories have different small-field behavior, leading to different ultraviolet cutoff scales. In particular, one interesting descendant of the Starobinsky model is the nonminimally coupled quadratic chaotic inflation. Although the standard quadratic chaotic inflation is ruled out by the recent Planck data, its nonminimally coupled version is in agreement with observational data and valid up to Planckian scales.

The incompleteness of the Dirac quantization scheme leads to a redundant set of solutions of the Wheeler-DeWitt equation for the wave function in the superspace of quantum cosmology. The selection of physically meaningful solutions that match quantum initial data can be attained by a reduction of the theory to the sector of true physical degrees of freedom and their canonical quantization. The resulting physical wave function unitarily evolving in the time variable introduced within this reduction can then be raised to the level of the cosmological wave function in the superspace of 3-metrics to form a needed subset of all solutions of the Wheeler-DeWitt equation. We apply this technique in several simple but nonlinear minisuperspace models and discuss (at both the classical and quantum level) the physical reduction in extrinsic time—the time variable determined in terms of extrinsic curvature (or momentum conjugated to the cosmological scale factor). Only this extrinsic time gauge can be consistently used in the vicinity of turning points and bounces where the scale factor reaches extremum and cannot monotonically parametrize the evolution of the system. Since the 3-metric scale factor is canonically dual to the extrinsic time variable, the transition from the physical wave function to the wave function in superspace represents a kind of generalized Fourier transform. This transformation selects square-integrable solutions of the Wheeler-DeWitt equation, which guarantees the Hermiticity of canonical operators of the Dirac quantization scheme. This makes this scheme consistent, a property that is not guaranteed with general solutions of the Wheeler-DeWitt equation. Semiclassically this means that wave functions are represented by oscillating waves in classically allowed domains of superspace and exponentially fall off in classically forbidden (underbarrier) regions. This is explicitly demonstrated in a flat Friedmann-Robertson-Walker (FRW) model with a scalar field having a constant negative potential, and for the case of a phantom scalar field with a positive potential. The FRW model of a scalar field with a vanishing potential does not lead to selection rules for solutions of the Wheeler-DeWitt equation, but this does not violate Hermiticity properties, because all these solutions are plane-wave type and describe cosmological dynamics without turning points and bounces. In models with turning points the description of classically forbidden domains goes beyond the original principles of the unitary quantum reduction to the physical sector, because it includes the complexification of the physical time variable or the complex nature of the physical Hamiltonian. However, this does not alter the formalism of the Wheeler-DeWitt equation, which continues describing underbarrier quantum dynamics in terms of real superspace variables.

A combined analysis of data on the isoscalar $S$-wave processes $\pi \pi \to \pi \pi$, $K\overline{K}$, $\eta \eta$ and on decays $J/\psi \to \varphi \pi \pi$, $\varphi K\overline{K}$ from the DM2, Mark III, and BES II Collaborations is performed to study $f_0$ mesons. The method of analysis is based on analyticity and unitarity and uses an uniformization procedure. In the analysis limited only to the multichannel $\pi \pi$-scattering data, two possible sets of parameters of the $f_0(500)$ were found: In both cases the mass was about 700 MeV but the total width was either about 680 or 1040 MeV. The extension of the analysis using only the DM2 and Mark III data on the $J/\psi$ decays does not allow us to choose between these sets. However, the data from BES II on the di-pion mass distribution in the decay $J/\psi \to \varphi {\pi }^{+}{\pi }^{-}$ clearly prefer the wider $f_0(500)$ state. Spectroscopic implications from the results of the analysis are also discussed.

We explore the phenomenology of virtual spin-1 contributions to the $h\to \gamma \gamma$ and $h\to Z\gamma$ decay rates in gauge extensions of the standard model. We consider generic Lorentz and gauge-invariant vector self-interactions, which can have nontrivial structure after diagonalizing the quadratic part of the action. Such features are phenomenologically relevant in models where the electroweak gauge bosons mix with additional spin-1 fields, such as occurs in little Higgs models, extra dimensional models, strongly coupled variants of electroweak symmetry breaking, and other gauge extensions of the standard model. In models where nonrenormalizable operators mix field strengths of gauge groups, the one-loop Higgs decay amplitudes can be logarithmically divergent, and we provide power counting for the size of the relevant counterterm. We provide an example calculation in a four-site moose model that contains degrees of freedom that model the effects of vector and axial-vector resonances arising from TeV scale strong dynamics.

We present results for the magnetic moment and magnetic polarizability of the neutron and the magnetic moment of the proton. These results are calculated using the uniform background field method on $32^3\times 64$ dynamical QCD lattices provided by the PACS-CS Collaboration as part of the ILDG. We use a uniform background magnetic field quantized by the periodic spatial volume. We investigate ways to improve the effective energy plots used to calculate magnetic polarizabilities, including the use of correlation matrix techniques with various source smearings.

We present a detailed numerical study of lepton-pair production via the Drell-Yan process above the $Z$-peak at the LHC. Our results consistently combine next-to-next-to-leading order QCD corrections and next-to-leading order electroweak effects, and include the leading photon-initiated processes using a recent extraction of the photon distribution function. We focus on the effects of electroweak corrections and of photon-photon scattering contributions, and demonstrate which kinematic distributions exhibit sensitivity to these corrections. We show that a combination of measurements allows them to be disentangled and separately determined.

We study the twist-3 three-gluon contribution to the single spin asymmetry in the light-hadron production in pp collision in the framework of the collinear factorization. We derive the corresponding cross-section formula in the leading order with respect to the QCD coupling constant. We also present a numerical calculation of the Relativistic Heavy Ion collider (RHIC) energy, using a model for the three-gluon correlation functions suggested by the asymmetry observed in the $D$-meson production at the RHIC.

We estimate the contribution of nonperturbative quark-gluon chromomagnetic interaction to the high energy elastic proton-proton cross section at a large momentum transfer. It is shown that this contribution is very large in the accessible kinematic region of the present experiments. We argue that Odderon which is the $P=C=-1$ partner of Pomeron, is governed by the spin-flip component related to the nonperturbative three-gluon exchange induced by the anomalous quark chromomagnetic moment. We discuss the possible spin effects in the elastic proton-proton and proton-antiproton scattering coming from the interference of spin-flip nonperturbative Odderon and non-spin-flip Pomeron exchanges.

We present a calculation of the hyperfine splittings in bottomonium using lattice nonrelativistic QCD. The calculation includes spin-dependent relativistic corrections through $\mathcal{O}(v^6)$, radiative corrections to the leading spin-magnetic coupling and, for the first time, nonperturbative effects of four-quark operators which enter at ${\alpha }_s^2{v}^3$. We also include the effect of $u$, $d$, $s$ and $c$ quark vacuum polarization. Our result for the $1S$ hyperfine splitting is $M_{\mathrm{\Upsilon }}(1S)-M_{{\eta }_b}(1S)=62.8(6.7)\mathrm{MeV}$. We find the ratio of $2S$ to $1S$ hyperfine splittings $(M_{\mathrm{\Upsilon }}(2S)-M_{{\eta }_b}(2S))/(M_{\mathrm{\Upsilon }}(1S)-M_{{\eta }_b}(1S))=0.425(25)$.

A class of strongly interacting many-body fermionic systems in $2+1$-dimensional nonrelativistic conformal field theory is examined via the gauge-gravity duality correspondence. The five-dimensional charged black hole with asymptotic Schrödinger isometry in the bulk gravity side introduces parameters of background density and finite particle number into the boundary field theory. We propose the holographic dictionary, and realize a quantum phase transition of this fermionic liquid with fixed particle number by tuning the background density $\beta$ at zero temperature. On the larger $\beta$ side, we find the signal of a sharp quasiparticle pole on the spectral function $A(k,\omega )$, indicating a well-defined Fermi surface. On the smaller $\beta$ side, we find only a hump with no sharp peak for $A(k,\omega )$, indicating the disappearance of the Fermi surface. The dynamical exponent $z$ of quasiparticle dispersion goes from being Fermi-liquid-like $z\simeq 1$ scaling at larger $\beta$ to a non-Fermi-liquid scaling $z\simeq 3/2$ at smaller $\beta$. By comparing the structure of Green’s function with Landau Fermi liquid theory and Senthil’s scaling ansatz, we further investigate the behavior of this quantum phase transition.

We study the possibility of an ultraviolet (UV) zero in the $n$-loop beta function of U(1) and non-Abelian gauge theories with $N_f$ fermions for large $N_f$. The effect of scheme transformations on the coefficients of different powers of $N_f$ in the $n$-loop term in the beta function is calculated. A general criterion is given for determining whether or not the $n$-loop beta function has a UV zero for large $N_f$. We compare the results with exact integral representations of the leading terms in the beta functions for the respective Abelian and non-Abelian theories in the limit $N_f\to \infty$ limit with $N_f\alpha$ finite. As part of this study, new analytic and numerical results are presented for certain coefficients, denoted $b_{n,n-1}$, that control the large-$N_f$ behavior at $n$-loop order in the beta function. We also investigate various test functions incorporating a power-law and essential UV zero in the beta function and determine their manifestations in series expansions in powers of coupling and in powers of $1/N_f$.

The equations of motion of a point particle interacting with its own field are defined in terms of a certain regularized self-field. Two of the leading methods for computing this regularized field are the mode-sum and effective-source approaches. In this work we unite these two distinct regularization schemes by generalizing traditional frequency-domain mode-sum calculations to incorporate effective-source techniques. For a toy scalar-field model we analytically compute an appropriate puncture field from which the regularized residual field can be calculated. To demonstrate the method, we compute the self-force for a scalar particle on a circular orbit in Schwarzschild spacetime. We also demonstrate the relation between the world tube and window function approaches to localizing the puncture field to the neighborhood of the worldline and show how the method reduces to the well-known mode-sum regularization scheme in a certain limit. This new computational scheme can be applied to cases where traditional mode-sum regularization is inadequate, such as in calculations at second perturbative order.

A model for determining the dimensionless spin parameter and mass of the black hole remnant of black hole-neutron star mergers with arbitrary initial black hole spin angular momentum, binary mass ratio, and neutron star mass and cold equation of state is formulated. Tests against numerical-relativity results are carried out, showing that both the dimensionless spin parameter and the final mass are accurately reproduced. For the first time, the behavior of both quantities and of the $l=2$, $m=2$, $n=0$ quasinormal mode frequency is inspected throughout the parameter space. Predictions of this frequency may be exploited to guide gravitational-wave modeling and detection efforts and to extract physical information from detected gravitational-wave signals that would help us break degeneracies between binary black hole and black hole-neutron star systems, improve our understanding of compact binary formation, and constrain the neutron star equation of state.

It has been recently pointed out that the excess of the gamma ray spectrum in the Fermi bubbles at low latitude can be well explained by the annihilation of dark matter particles. The best-fit candidate corresponds to the annihilation of a dark matter with mass of around 62 GeV into $b\overline{b}$ with the cross section, $\sigma v\simeq 3.3\times {10}^{-26}{\mathrm{cm}}^3/\mathrm{s}$, or the annihilation of a dark matter with mass of around 10 GeV into a tau lepton pair with the cross section, $\sigma v\simeq 5.6\times {10}^{-27}{\mathrm{cm}}^3/\mathrm{s}$. We point out that the Higgs portal dark matter models are perfectly compatible with this interpretation of the dark matter annihilation, satisfying other phenomenological constraints. We also show that the parameter region which reproduces the best-fit values can be partly explored by the future direct dark matter search at the XENON1T.