We study flavor and gravitational anomalies in Galilean theories coupled to torsional Newton-Cartan backgrounds. We establish that the relativistic anomaly inflow mechanism with an appropriately modified anomaly polynomial can be used to generate these anomalies. Similar to the relativistic case, we find that Galilean anomalies also survive only in even dimensions. Further, these anomalies only effect the flavor and rotational symmetries of a Galilean theory; in particular, the Milne boost symmetry remains nonanomalous. We also extend the transgression machinery used in relativistic fluids to Galilean fluids, and use it to determine how these anomalies affect the constitutive relations of a Galilean fluid. Unrelated to the Galilean fluids, we propose an analogue of the off-shell second law of thermodynamics for relativistic fluids, to include torsion and a conserved spin current in the vielbein formalism. Interestingly, we find that even in the absence of spin current and torsion the entropy currents in the two formalisms are different: while the usual entropy current gets a contribution from the gravitational anomaly, the entropy current in the vielbein formalism does not have any anomaly-induced part.

Curvature squared terms, when added to the Einstein-Hilbert action and treated nonperturbatively, generically result in the propagation of an extra massive scalar state and an extra massive spin-2 ghost state. Using the Stückelberg trick, we study the high-energy limit in which the mass of the spin-2 state is taken to zero, with strong-coupling scales held fixed. The Stückelberg approach makes transparent the interplay between the ghost graviton and the healthy graviton which allows the theory to evade the usual ${\mathrm{\Lambda }}_3$ strong coupling scale of massive gravity and become renormalizable, at the expense of stability.

We calculate leading-order medium photon yields from a quark-gluon plasma using ($3+1$)-dimensional anisotropic hydrodynamics. Nonequilibrium corrections to the photon rate are taken into account using a self-consistent modification of the particle distribution functions and the corresponding anisotropic hard-loop fermionic self-energies. We present predictions for the high-energy photon spectrum and photon elliptic flow as a function of transverse momentum, shear viscosity, and initial momentum-space anisotropy. Our findings indicate that high-energy photon production is sensitive to the assumed level of initial momentum-space anisotropy of the quark-gluon plasma. As a result, it may be possible to experimentally constrain the early-time momentum-space anisotropy of the quark-gluon plasma generated in relativistic heavy-ion collisions using high-energy photon yields.

We use a recently obtained resummed quark propagator at finite temperature which takes into account both the chromoelectric scale $gT$ and the chromomagnetic scale $g^{2}T$ through the Gribov action. The electric scale generates two massive modes whereas the magnetic scale produces a new massless spacelike mode in the medium. Moreover, the nonperturbative quark propagator is found to contain no discontinuity in contrast to the standard perturbative hard thermal loop approach. Using this nonperturbative quark propagator and vertices constructed using the Slavnov-Taylor identity, we compute the nonperturbative dilepton rate at vanishing three-momentum at one-loop order. The resulting rate has a rich structure at low energies due to the inclusion of the nonperturbative magnetic scale. We also calculate the quark number susceptibility, which is related to the conserved quark number density fluctuation in the deconfined state. Both the dilepton rate and quark number susceptibility are compared with results from lattice quantum chromodynamics and the standard hard thermal loop approach. Finally, we discuss how the absence of a discontinuity in the imaginary part of the nonperturbative quark propagator makes the results for both dilepton production and quark number susceptibility dramatically different from those in perturbative approaches and seemingly in conflict with known lattice data.

The variational approach to QCD in Coulomb gauge developed previously by the Tübingen group is improved by enlarging the space of the quark trial vacuum wave functionals through a new Dirac structure in the quark-gluon coupling. Our Ansatz for the quark vacuum wave functional ensures that all linear divergences cancel in the quark gap equation resulting from the minimization of the energy calculated to two-loop order. The logarithmic divergences are absorbed in a renormalized coupling which is adjusted to reproduce the phenomenological value of the quark condensate. We also unquench the gluon propagator and show that the unquenching effects are generally small and amount to a small reduction in the midmomentum regime.

Benefiting from the index spinorial formalism, the Killing spinor equation is integrated in six-dimensional spacetimes. The integrability conditions for the existence of a Killing spinor are worked out and the Killing spinors are classified into two algebraic types; in the first type the scalar curvature of the spacetime must be negative, while in the second type the spacetime must be an Einstein manifold. In addition, the equations that define Killing-Yano (KY) and closed conformal Killing-Yano (CCKY) tensors are expressed in the index notation and, as consequence, all nonvanishing KY and CCKY tensors that can be generated from a Killing spinor are made explicit.

Many theories beyond the standard model (BSM) contain new $CP$-odd and $CP$-even neutral scalars $\varphi =\{A,H\}$, and new vectorlike fermions (${\psi }_{VL}$). The couplings of the $CP$-odd scalar $A$ to two standard model (SM) gauge bosons cannot occur from renormalizable operators in a $CP$-conserving sector, but can be induced at the quantum loop level. We compute these effective couplings at the 1-loop level induced by the SM fermions and vectorlike fermions, present analytical expressions for them, and plot them numerically. Using the 8 TeV Large Hadron Collider (LHC) $\gamma \gamma$, ${\tau }^{+}{\tau }^{-}$ and $t\overline{t}$ channel data, we derive constraints on the effective couplings of the $\varphi$ to standard model gauge bosons and fermions. We present the gluon-fusion channel cross sections of the $\varphi$ at the 8 and 14 TeV LHC, and its branching ratios into SM fermion and gauge-boson pairs. We first present our results in a model independent manner, and then we provide results for some simple models containing $\varphi$ and ${\psi }_{VL}$ in the singlet and doublet representations of $SU(2)$. In the doublet case, we focus on the two-Higgs-doublet (2HDM) Type-II and Type-X models in the alignment limit.

All (un)polarized transverse momentum dependent functions (TMDs), both distribution and fragmentation functions, are defined with the same universal soft function, which cancels spurious rapidity divergences within an individual TMD and renders them well-defined hadronic quantities. Moreover, it is independent of the kinematics, whether it is Drell-Yan, deep inelastic scattering, or $e^{+}{e}^{-}\to 2$ hadrons. In this paper, we provide this soft function at next-to-next-to-leading order (NNLO), necessary for the calculation of all TMDs at the same order, and to perform the resummation of large logarithms at next-to-next-to-next-to-leading-logarithmic accuracy. From the results we obtain the $D$ function at NNLO, which governs the evolution of all TMDs. This work represents the first independent and direct calculation of this quantity. Given the all-order relation through a Casimir scaling between the soft function relevant for gluon TMDs and the one for quark TMDs, we also obtain the first at NNLO. The used regularization method to deal with the rapidity divergences is discussed as well.

Deviations from the standard model prediction have been observed in several leptonic and semileptonic $B$ meson decays to $\tau \nu$ final states mediated via $b\to u$ and $b\to c$ charged current interactions. The measured value of the ratio of branching ratios $R_{\pi }^l$ of $B^{-}\to {\tau }^{-}{\nu }_{\tau }$ to $B^0\to {\pi }^{+}{l}^{-}\nu$ decays, where $l=(e,\mu )$, is larger than the standard model prediction by more than a factor of 2. Similarly, a combined excess of $3.9\sigma$ from the standard model expectation has been reported by HFAG for the values of $R_D$ and $R_{D^{*}}$, where $R_{D,D^{*}}$ represents the ratio of branching ratios of $B\to (D,D^{*})\tau \nu$ to corresponding $B\to (D,D^{*})l\nu$ decays, respectively. Very recently, a hint of lepton flavor violation has been observed in the ratio of branching fractions of $B\to K{e}^{+}{e}^{-}$ to $B\to K{\mu }^{+}{\mu }^{-}$ decays as well. In this context, we employ an effective Lagrangian approach to study the decay branching fractions and the ratio of branching fractions of ${\mathrm{\Lambda }}_b\to {\mathrm{\Lambda }}_{c}l\nu$ and ${\mathrm{\Lambda }}_b\to pl\nu$ decays within the standard model and beyond. We constrain the new physics parameter space using the existing experimental data on $R_D$, $R_{D^{*}}$, and $R_{\pi }^l$. We give predictions for various observables in the context of various new physics scenarios.

A detection technique for ultra-high-energy cosmic rays, complementary to the fluorescence technique, would be the use of the molecular bremsstrahlung radiation emitted by low-energy ionization electrons left after the passage of the showers in the atmosphere. In this article, a detailed estimate of the spectral intensity of photons at ground level originating from this radiation is presented. The spectral intensity expected from the passage of the high-energy electrons of the cascade is also estimated. The absorption of the photons in the plasma of electrons and neutral molecules is shown to be negligible. The obtained spectral intensity is shown to be $2\times 10^{-21}\mathrm{W}{\mathrm{cm}}^{-2}{\mathrm{GHz}}^{-1}$ at 10 km from the shower core for a vertical shower induced by a proton of $10^{17.5}\mathrm{eV}$. In addition, a recent measurement of bremsstrahlung radiation in air at gigahertz frequencies from a beam of electrons produced at 95 keV by an electron gun is also discussed and reasonably reproduced by the model.

The momentum-weighted sum of the charges of tracks associated to a jet is sensitive to the charge of the initiating quark or gluon. This paper presents a measurement of the distribution of momentum-weighted sums, called jet charge, in dijet events using $20.3{\mathrm{fb}}^{-1}$ of data recorded with the ATLAS detector at $\sqrt{s}=8\mathrm{TeV}$ in $pp$ collisions at the LHC. The jet charge distribution is unfolded to remove distortions from detector effects and the resulting particle-level distribution is compared with several models. The $p_T$ dependence of the jet charge distribution average and standard deviation are compared to predictions obtained with several leading-order and next-to-leading-order parton distribution functions. The data are also compared to different Monte Carlo simulations of QCD dijet production using various settings of the free parameters within these models. The chosen value of the strong coupling constant used to calculate gluon radiation is found to have a significant impact on the predicted jet charge. There is evidence for a $p_{\mathrm{T}}$ dependence of the jet charge distribution for a given jet flavor. In agreement with perturbative QCD predictions, the data show that the average jet charge of quark-initiated jets decreases in magnitude as the energy of the jet increases.

We study the phenomenon of negative energy densities in quantum field theories with self-interaction. Specifically, we consider a class of integrable models (including the sinh-Gordon model) in which we investigate the expectation value of the energy density in one-particle states. In this situation, we classify the possible form of the stress-energy tensor from first principles. We show that one-particle states with negative energy density generically exist in nonfree situations, and we establish lower bounds for the energy density (quantum energy inequalities). Demanding that these inequalities hold reduces the ambiguity in the stress-energy tensor, in some situations fixing it uniquely. Numerical results for the lowest spectral value of the energy density allow us to demonstrate how negative energy densities depend on the coupling constant and on other model parameters.

The uniqueness of a static asymptotically flat photon sphere for a static black hole solution in the Einstein-Maxwell-dilaton theory with an arbitrary coupling constant is proposed. Using the conformal positive energy theorem, we show that the dilaton photon sphere subject to the nonextremality condition constitutes a cylinder over a topological sphere.

We study the possibility that inflation is driven by a massive vector field with $SO(3)$ global symmetry nonminimally coupled to gravity. From an $E^3$-invariant Robertson-Walker metric we propose an Ansatz for the vector field, allowing us to study the evolution of the system. We study the behavior of the equations of motion using the methods of the theory of dynamical systems and find exponential inflationary regimes.

Folding uncertainty in theoretical models into Bayesian parameter estimation is necessary in order to make reliable inferences. A general means of achieving this is by marginalizing over model uncertainty using a prior distribution constructed using Gaussian process regression (GPR). As an example, we apply this technique to the measurement of chirp mass using (simulated) gravitational-wave signals from binary black holes that could be observed using advanced-era gravitational-wave detectors. Unless properly accounted for, uncertainty in the gravitational-wave templates could be the dominant source of error in studies of these systems. We explain our approach in detail and provide proofs of various features of the method, including the limiting behavior for high signal-to-noise, where systematic model uncertainties dominate over noise errors. We find that the marginalized likelihood constructed via GPR offers a significant improvement in parameter estimation over the standard, uncorrected likelihood both in our simple one-dimensional study, and theoretically in general. We also examine the dependence of the method on the size of training set used in the GPR; on the form of covariance function adopted for the GPR, and on changes to the detector noise power spectral density.

We give predictions for the nonperturbative (intrinsic) contribution to the $s(x)-\overline{s}(x)$ asymmetry of the nucleon sea. For this purpose we use different light-front wave functions inspired by the AdS/QCD formalism, together with a model of the nucleon in terms of meson-baryon fluctuations. The holographic wave functions for an arbitrary number of constituents, recently derived by us, give results quite close to known parametrizations that appear in the literature.

We suggest that the recently observed diphoton excess at 750 GeV comes from a quasidegenerate bunch of gauge singlet scalars produced and decaying through one or more vectorlike fermions. This explains the broad nature of the resonance, even though the decay is loop mediated. At the same time, the model keeps the new Yukawa couplings in the perturbative region, which is necessary for the stability of the potential.

We study the phenomenology of the exotic Higgs bosons in the Georgi-Machacek model at future electron-positron colliders such as the International Linear Collider (ILC), assuming the collision energies of 500 GeV and 1 TeV. We show that the existence of the neutral and singly charged Higgs bosons in the 5-plet representation under the custodial $SU(2{)}_V$ symmetry can be readily identified by studying various energy and invariant mass distributions of the $W^{+}{W}^{-}Z$ final state. Moreover, their masses can be determined with sufficiently high precision to test the mass degeneracy, a feature due to the custodial symmetry of the model. A synergy between such searches at the ILC and the doubly charged Higgs search at the LHC will make the 5-plet Higgs boson study more comprehensive.

We study the radiative corrections induced by the triple Higgs boson coupling $hhh$ in the three-body decay $h\to Z{Z}^{*}\to Zl\overline{l}$. We show that these corrections are potentially sensitive to the specific value of this coupling in the Standard Model and the two Higgs doublet model (2HDM). These effects may induce corrections to the integrated decay width of the three-body decay of order few percent in the 2HDM and thus open a new window to test the Higgs boson self-interaction in physics beyond the Standard Model.

The three-dimensional momenta of quarks inside a hadron are encoded in transverse momentum-dependent parton distribution functions (TMDs). This work presents an exploratory lattice QCD study of a TMD observable in the pion describing the Boer-Mulders effect, which is related to polarized quark transverse momentum in an unpolarized hadron. The primary goal is to gain insight into the behavior of TMDs as a function of a Collins-Soper evolution parameter, $\widehat{\zeta }$, which quantifies the rapidity difference between the hadron momentum and a vector describing the trajectory of the struck quark, e.g., in a semi-inclusive deep-inelastic scattering (SIDIS) process. The lattice calculation, performed at the pion mass $m_{\pi }=518\mathrm{MeV}$, utilizes a definition of TMDs via hadronic matrix elements of a quark bilocal operator with a staple-shaped gauge connection; in this context, the evolution parameter is related to the staple direction. By parametrizing the aforementioned matrix elements in terms of invariant amplitudes, the problem can be cast in a Lorentz frame suited for the lattice calculation. Aided by the lower mass of the pion, compared to the nucleon studied previously, the present investigation of pion TMD observables constitutes an important step towards the quantitative study of the physically important regime of large relative rapidity where the dependence on $\widehat{\zeta }$ appears to approach a limit. Although matching to perturbative evolution equations in $\widehat{\zeta }$ is not yet available, extrapolations based on Ansätze containing inverse powers of $\widehat{\zeta }$ yield stable results with an uncertainty as low as 20%, and both upper and lower bounds for the asymptotics are obtained. In passing, the similarity between the Boer-Mulders effects extracted in the pion and the nucleon is noted.