We present a Yang-Mills-Higgs (YMH) gauge theory in which structure constants of the gauge group may depend on Higgs fields. The data of the theory are encoded in the bundle $E\to M$, where the base $M$ is the target space of Higgs fields and fibers carry information on the gauge group. $M$ is equipped with a metric $g$ and $E$ carries a connection $\nabla$. If $\nabla$ is flat, $R_{\nabla }=0$, there is a local field redefinition which gives back the standard YMH gauge theory. If $R_{\nabla }\ne 0$, one obtains a new class of gauge theories. In this case, contrary to the standard wisdom of the YMH theory, the space $(M,g)$ may have no isometries. We build a simple example which illustrates this statement.

Goncalves et al. [Phys. Rev. D 75, 124023 (2007)] derived a nonrelativistic limit of the generalized Dirac Hamiltonian in the presence of a gravitational wave, using the exact Foldy-Wouthuysen transformation. This gave rise to the intriguing notion that spin precession may occur even in the absence of a magnetic field. We argue that this effect is not physical as it is the result of a gauge-variant term that was an artifact of a flawed application of the exact Foldy-Wouthuysen transformation. In this paper we derive the correct nonrelativistic limit of the generalized Dirac Hamiltonian in the presence of a gravitational wave, using both the exact and standard Foldy-Wouthuysen transformation. We show that both transformations consistently produce a Hamiltonian where all terms are gauge invariant. Unfortunately however, we also show that this means the novel spin-precession effect does not exist.

Modified Newtonian dynamics (MOND) is an empirical theory originally proposed to explain the rotation curves of spiral galaxies by modifying the gravitational acceleration, rather than by invoking dark matter. Here, we set constraints on MOND using an up-to-date compilation of kinematic tracers of the Milky Way and a comprehensive collection of morphologies of the baryonic component in the Galaxy. In particular, we find that the so-called “standard” interpolating function cannot explain at the same time the rotation curve of the Milky Way and that of external galaxies for any of the baryonic models studied, while the so-called “simple” interpolating function can for a subset of models. Upcoming astronomical observations will refine our knowledge on the morphology of baryons and will ultimately confirm or rule out the validity of MOND in the Milky Way. We also present constraints on MOND-like theories without making any assumptions on the interpolating function.

In this work, we consider a generalized gravitational theory that contains the Einstein term, a scalar field, and the quadratic Gauss-Bonnet (GB) term. We focus on the early-universe dynamics, and demonstrate that a simple choice of the coupling function between the scalar field and the Gauss-Bonnet term and a simplifying assumption regarding the role of the Ricci scalar can lead to new, analytical, elegant solutions with interesting characteristics. We first argue, and demonstrate in the context of two different models, that the presence of the Ricci scalar in the theory at early times (when the curvature is strong) does not affect the actual cosmological solutions. By considering therefore a pure scalar-GB theory with a quadratic coupling function we derive a plethora of interesting, analytic solutions: for a negative coupling parameter, we obtain inflationary, de Sitter-type solutions or expanding solutions with a de Sitter phase in their past and a natural exit mechanism at later times; for a positive coupling function, we find instead singularity-free solutions with no big bang singularity. We show that the aforementioned solutions arise only for this particular choice of coupling function, a result that may hint at some fundamental role that this coupling function may hold in the context of an ultimate theory.

Precise measurements of the baryon acoustic oscillation (BAO) scale as a standard ruler in the clustering pattern of large-scale structure is a central goal of current and future galaxy surveys. The BAO peak may be sharpened using the technique of density-field reconstruction, in which the bulk displacements of galaxies are estimated using a Zel’dovitch approximation. We use numerical simulations to demonstrate how the accuracy of this approximation depends strongly on local environment, and how this information may be used to construct an improved BAO measurement through environmental reweighting and using higher-order perturbation theory. We outline further applications of the displacement field for testing cosmological models.

The validity of the semiclassical approximation is investigated during the preheating phase in models of chaotic inflation using a modification of a criterion previously proposed for semiclassical gravity. If the modified criterion is violated then fluctuations of the two-point function for the quantum fields are large and the semiclassical approximation is not valid. Evidence is provided that the semiclassical approximation breaks down during the early stages of preheating, well before either scattering effects or backreaction effects are important.

We investigate simplified dark matter models where the dark matter candidate is a Dirac fermion charged only under a new gauge symmetry. In this context one can understand dynamically the stability of the dark matter candidate and the annihilation through the new gauge boson is not velocity suppressed. We present the simplest Dirac dark matter model charged under the local $B-L$ gauge symmetry. We discuss in great detail the theoretical predictions for the annihilation into two photons, into the standard model Higgs and a photon, and into the $Z$ gauge boson and a photon. Our analytical results can be used for any Dirac dark matter model charged under an Abelian gauge symmetry. The numerical results are shown in the $B-L$ dark matter model. We discuss the correlation between the constraints on the model from collider searches and dark matter experiments.

We analyze the quasispherical accretion in the presence of axisymmetric curl. The condition allowing the curl to reach the central object is formulated. Possible implications of the solution to the theory of turbulent accretion are discussed.

We propose a new system suitable for studying analog gravity effects, consisting of a gas flowing in a duct with a compliant wall. Effective transonic flows are obtained from uniform, low-Mach-number flows through the reduction of the one-dimensional speed of sound induced by the wall compliance. We show that the modified equation for linear perturbations can be written in a Hamiltonian form. We perform a one-dimensional reduction consistent with the canonical formulation, and deduce the analog metric along with the first dispersive term. In a weak dispersive regime, the spectrum emitted from a sonic horizon is numerically shown to be Planckian, and with a temperature fixed by the analog surface gravity.

We study the effects of light scalar mesons on the Skyrmion properties by constructing and examining a mesonic model including pion, rho meson, and omega meson fields as well as two-quark and four-quark scalar meson fields. In our model, the physical scalar mesons are defined as mixing states of the two- and four-quark fields. We first omit the four-quark scalar meson field from the model and find that when there is no direct coupling between the two-quark scalar meson and the vector mesons, the soliton mass is smaller and the soliton size is larger for lighter scalar mesons; when direct coupling is switched on, as the coupling strength increases, the soliton becomes heavy, and the radius of the baryon number density becomes large as the repulsive force arising from the $\omega$ meson becomes strong. We then include the four-quark scalar meson field in the model and find that mixing between the two-quark and four-quark components of the scalar meson fields also affects the properties of the soliton. When the two-quark component of the lighter scalar meson is increased, the soliton mass decreases and the soliton size increases.

We demonstrate that the $3\sigma$ excess observed by ATLAS in the $Z+\mathrm{MET}$ channel can be explained within the context of the MSSM. Using the freedom inherent in the pMSSM, we perform a detailed analysis of the parameter space and find a scenario that describes the excess while simultaneously complying with all other search constraints from the Run I data at 7 and 8 TeV, including the $Z+\mathrm{MET}$ analysis by CMS. We generate a small sample of simplified models, using promising models from our existing pMSSM sample as seeds, and study their properties. The successful region is described by the production of $1^{\mathrm{st}}/2^{\mathrm{nd}}$ generation squark pairs, followed by their decay into a bino-like neutralino which in turn decays into a Higgsino-like LSP triplet by emitting a $Z$ boson, i.e., $\tilde{q}\to \tilde{B}\to \tilde{h}$ with $\tilde{q}={\tilde{Q}}_L$, ${\tilde{u}}_R$, or ${\tilde{d}}_R$. The sweet spot for the sparticle spectrum is found to have squark masses in the 500–750 GeV range, with bino masses near 350 GeV with a mass splitting of 150–200 GeV with the Higgsino LSP. If this excess holds, then this scenario predicts that a signal will be observed in the $0l+\mathrm{jets}$ and/or $1l+\mathrm{jets}$ searches in the early operations of Run II.

Adding a scalar triplet to the Standard Model is one of the simplest ways of giving mass to neutrinos, providing at the same time a mechanism to stabilize the theory’s vacuum. In this paper, we revisit these aspects of the type-II seesaw model pointing out that the bounded-from-below conditions for the scalar potential in use in the literature are not correct. We discuss some scenarios where the correction can be significant and sketch the typical scalar boson profile expected by consistency.

A recent lattice study of the Landau-gauge overlap quark propagator has shown a connection between center vortices and dynamical chiral symmetry breaking in SU(3) gauge theory. We further investigate this relationship through an exploration of the connection to the instanton degrees of freedom. After identifying center vortices on the lattice in maximal center gauge, we smooth configurations using multiple algorithms. We are able to create an instanton liquid-like background on configurations consisting solely of center vortices, analogous to that found on Monte-Carlo generated configurations after similar smoothing. Through calculations of the static quark potential and Landau-gauge overlap propagator, we show that this background is able to reproduce all salient long-range features of the original configurations. Thus we conclude that the information necessary to recreate the long-range structure of SU(3) gauge theory is contained within the center vortex degrees of freedom.

The gluon polarization functional is evaluated for a generic linear covariant gauge and for any space dimension in pure Yang-Mills SU(N) theory up to second order in a generalized perturbation theory, where the zeroth order action is freely chosen and can be determined by some variational method. Some numerical data are given for the gluon propagator in the Landau gauge and compared with the Feynman gauge. A comparison is given for several variational methods that can be set up by the knowledge of the second order polarization.

Precise knowledge of the strange and antistrange quark distributions of the nucleon is a major step toward better understanding of the strong interaction and the nucleon structure. Moreover, the $s-\overline{s}$ asymmetry in the nucleon plays an important role in some physical processes involving hadrons. The goal of this paper is the study of intrinsic strange contribution to the strange sea of the nucleon. To this aim, we calculate the intrinsic strange distributions from the various light-cone models, including Brodsky, Hoyer, Peterson, and Sakai (BHPS); scalar five-quark; and meson-baryon models and then compare their results. These models can lead to the rather different distributions for the intrinsic strange that are dominated in different values of $x$. Furthermore, the meson-baryon model leads to the $s-\overline{s}$ asymmetry that can be comparable in some situations to the result obtained from the global analysis of PDFs. We also present a simple parametrization for each model prediction of intrinsic strange distribution.

We extend the recent computation of Higgs boson production in association with a jet through next-to-next-to-leading order in perturbative QCD by including decays of the Higgs boson to electroweak vector bosons. This allows us to compute fiducial cross sections and kinematic distributions including realistic selection criteria for the Higgs boson decay products. As an illustration, we present results for $pp\to H+j\to \gamma \gamma +j$ closely following the ATLAS 8 TeV analysis and for $pp\to H+j\to W^{+}{W}^{-}+j\to e^{+}{\mu }^{-}\nu \overline{\nu }+j$ in a CMS-like 13 TeV setup.

We evaluate the forward Compton scattering off the proton, based on Kramers-Kronig kind of relations which express the Compton amplitudes in terms of integrals of total photoabsorption cross sections. We obtain two distinct fits to the world data on the unpolarized total photoabsorption cross section and evaluate the various spin-independent sum rules using these fits. For the sum of proton electric and magnetic dipole polarizabilities governed by the Baldin sum rule, we obtain the following average (between the two fits): ${\alpha }_{E1}+{\beta }_{M1}=14.0(2)\times 10^{-4}{\mathrm{fm}}^3$. An analogous sum rule involving the quadrupole polarizabilities of the proton is evaluated too. The spin-independent forward amplitude of proton Compton scattering is evaluated in a broad energy range. The results are compared with previous evaluations and the only experimental data point for this amplitude (at 2.2 GeV). We remark on sum rules for the elastic component of polarizabilities.

We investigate the exclusive semileptonic decays $J/\psi \to D_{(s)}^{(*)-}{\ell }^{+}{\nu }_{\ell }$, where $\ell =e,\mu$, within the Standard Model. The relevant transition form factors are calculated in the framework of a relativistic constituent quark model with built-in infrared confinement. Our calculations predict the branching fractions $\mathcal{B}(J/\psi \to D_{(s)}^{(*)-}{\ell }^{+}{\nu }_{\ell })$ to be of the order of $10^{-10}$ for $D_s^{(*)-}$ and $10^{-11}$ for $D^{(*)-}$. Most of our numerical results are consistent with other theoretical studies. However, some branching fractions are larger than those calculated in QCD sum rules approaches but smaller than those obtained in the covariant light-front quark model by a factor of about 2–3.

We present a calculation of the SU(3)-breaking corrections to the hyperon transition vector form factors to $\mathcal{O}(p^4)$ in heavy-baryon chiral perturbation theory with finite-range regularization. Both octet and decuplet degrees of freedom are included. We formulate a chiral expansion at the kinematic point $Q^2=-(M_{B_1}-M_{B_2}{)}^2$, which can be conveniently accessed in lattice QCD. The two unknown low-energy constants at this point are constrained by lattice QCD simulation results for the ${\mathrm{\Sigma }}^{-}\to n$ and ${\mathrm{\Xi }}^0\to {\mathrm{\Sigma }}^{+}$ transition form factors. Hence, we determine lattice-informed values of $f_1$ at the physical point. This work constitutes progress toward the precise determination of $|V_{us}|$ from hyperon semileptonic decays.

With the potential prospects of the $\mathrm{\Upsilon }(1S)$ at high-luminosity dedicated heavy-flavor factories, the bottom-changing $\mathrm{\Upsilon }(1S)\to B_c\pi$, $B_{c}K$ weak decays are studied with the pQCD approach. It is found that branching ratio for the color-favored and CKM-favored $\mathrm{\Upsilon }(1S)\to B_c\pi$ decay can reach up to $\mathcal{O}(10^{-11})$. So the $\mathrm{\Upsilon }(1S)\to B_c\pi$ decay might be measured promisingly by the future experiments.