We present a simultaneous study of baryon-meson systems containing a bottom degree of freedom, either as a quark or as an antiquark. This produces two different types of structures: the $NB$ system, subject to quark antisymmetry effects and whose existence would generate explicit exotic states; and the $N\overline{B}$ system, subject to the coupling to heavy baryon–light meson systems and whose existence would represent a higher Fock space component of the bottom baryon spectrum. Both systems have been studied within the framework of a full-fledged chiral constituent quark model tuned in the description of the baryon and meson spectra and the $NN$ interaction. Although the masses of the constituents are larger than its partners in the charm sector, we do not observe a proliferation of bound states. This is due to the coupled-channel mechanism that governs the dynamics for most spin-isospin channels, and requires, in order to have a bound state, several conditions that are difficult to be met at the same time. Our results point to the existence of a deep $NB$ bound state in the $(T)J^P=(2)3/2^{-}$ channel, as a consequence of the reduction of the mass difference between pseudoscalar and vector mesons when the mass of the heavy quark increases. The same effect gives rise to a resonance at threshold in the $(T)J^P=(0)1/2^{-}$ channel, the best candidate for an exotic state among the channels that do not contain a $\mathrm{\Delta }$ isobar. In the $N\overline{B}$ system, a few channels may lodge molecular or compact hadrons with a five-quark structure, being specially suited the $(T)J^P=(0)1/2^{-}$ and $(T)J^P=(1)5/2^{-}$ channels.

We study the single graviton production at the CERN LHC using the $k_T$-factorization approach of QCD. We consider the Arkani-Hamed-Dimopoulos-Dvali scenario and Randall-Sundrum model with one warped extra dimension and derive the production amplitudes for spin-2 (Kaluza-Klein excitation of the graviton) and spin-0 (radion) states, including subsequent graviton decay into the dilepton or diphoton pairs. We use the transverse momentum dependent (unintegrated) parton densities in a proton obtained from the Ciafaloni-Catani-Fiorani-Marchesini evolution equation, which resums the leading logarithmic small-$x$ corrections to the production cross sections, and estimate the uncertainties of our predictions. We demonstrate that the small-$x$ effects can manifest themselves in the different angular distributions of graviton decay products and give some examples of what these distributions can look like at the LHC energies.

We report on a numerical study of the Boltzmann equation including $2\leftrightarrow 2$ scatterings of gluons and quarks in an overoccupied glasma undergoing longitudinal expansion. We find that when a cascade of gluon number to the infrared occurs, corresponding to an infrared enhancement analogous to a transient Bose-Einstein condensate, gluon distributions qualitatively reproduce the results of classical-statistical simulations for the expanding glasma. These include key features of the distributions that are not anticipated in the “bottom-up” thermalization scenario. We also find that quark distributions, like those of gluons, satisfy self-similar scaling distributions in the overoccupied glasma. We discuss the implications of these results for a deeper understanding of the self-similarity and universality of parton distributions in the glasma.

We study decay properties of the $P$-wave charmed baryons using the method of light-cone QCD sum rules, including the $S$-wave decays of the flavor ${\overline{\mathbf{3}}}_F$ $P$-wave charmed baryons into ground-state charmed baryons accompanied by a pseudoscalar meson ($\pi$ or $K$) or a vector meson ($\rho$ or $K^{*}$), and the $S$-wave decays of the flavor ${\mathbf{6}}_F$ $P$-wave charmed baryons into ground-state charmed baryons accompanied by a pseudoscalar meson ($\pi$ or $K$). We study both two-body and three-body decays which are kinematically allowed. We find two mixing solutions from internal $\rho$- and $\lambda$-mode excitations, which can well describe both masses and decay properties of the ${\mathrm{\Lambda }}_c(2595)$, ${\mathrm{\Lambda }}_c(2625)$, ${\mathrm{\Xi }}_c(2790)$ and ${\mathrm{\Xi }}_c(2815)$. We also discuss the possible interpretations of $P$-wave charmed baryons for the ${\mathrm{\Sigma }}_c(2800)$, ${\mathrm{\Xi }}_c(2930)$, ${\mathrm{\Xi }}_c(2980)$, and the recently observed ${\mathrm{\Omega }}_c(3000)$, ${\mathrm{\Omega }}_c(3050)$, ${\mathrm{\Omega }}_c(3066)$, ${\mathrm{\Omega }}_c(3090)$, and ${\mathrm{\Omega }}_c(3119)$.

The initial singularity is the most troubling feature of the standard cosmology, which quantum effects are hoped to resolve. In this paper, we study quantum cosmology with conformal (Weyl) invariant matter. We show that it is natural to extend the scale factor to negative values, allowing a large, collapsing universe to evolve across a quantum “bounce” into an expanding universe like ours. We compute the Feynman propagator for Friedmann-Robertson-Walker backgrounds exactly, identifying curious pathologies in the case of curved (open or closed) universes. We then include anisotropies, fixing the operator ordering of the quantum Hamiltonian by imposing covariance under field redefinitions and again finding exact solutions. We show how complex classical solutions allow one to circumvent the singularity while maintaining the validity of the semiclassical approximation. The simplest isotropic universes sit on a critical boundary, beyond which there is qualitatively different behavior, with potential for instability. Additional scalars improve the theory’s stability. Finally, we study the semiclassical propagation of inhomogeneous perturbations about the flat, isotropic case, at linear and nonlinear order, showing that, at least at this level, there is no particle production across the bounce. These results form the basis for a promising new approach to quantum cosmology and the resolution of the big bang singularity.

We consider a class of baryogenesis models where the Lagrangian in the visible sector is charge-parity ($CP$) invariant and a baryon asymmetry is produced only when quantum statistics is taken into account. The $CP$ symmetry is broken by matter effects, namely the assumption that the primordial plasma contains another asymmetric species, such as dark matter. Out-of-equilibrium baryon number violating decays can then generate an asymmetry through Bose enhancement and/or Pauli blocking of certain decay channels.

We investigate the approach of pure SU(2) lattice gauge theory with the Wilson action to its continuum limit using the deconfining phase transition, the gradient flow and the cooling flow to set the scale. For the gradient and cooling scales we explore three different energy observables and two distinct reference values for the flow time. When the aim is to follow scaling towards the continuum limit, one gains at least a factor of 100 in computational efficiency by relying on the gradient instead of the deconfinement scale. Using cooling instead of the gradient flow one gains another factor of at least 34 in computational efficiency on the gradient flow part without any significant loss in the accuracy of scale setting. Concerning our observables, the message is to keep it simple. The Wilson action itself performs as well as or even better than the other two observables explored. Two distinct fitting forms for scaling are compared, of which one connects to asymptotic scaling. Differences of the obtained estimates show that systematic errors of length ratios, though only about 1%, can be considerably larger than statistical errors of the same observables.

Recently, the Cachazo-He-Yuan (CHY) approach has been extended to the loop level, but the resulting loop integrand has propagators that are linear in the loop momentum unlike Feynman’s. In this paper, we present a new technique that directly produces quadratic propagators identical to Feynman’s from the CHY approach. This paper focuses on the ${\Phi }^3$ theory, but extensions to other theories are briefly discussed. In addition, our proposal has an interesting geometric meaning; we can interpret this new formula as a unitary cut on a higher genus Riemann surface.

We extend the adiabatic regularization method for an expanding universe to include the Yukawa interaction between quantized Dirac fermions and a homogeneous background scalar field. We give explicit expressions for the renormalized expectation values of the stress-energy tensor $⟨T_{\mu \nu }⟩$ and the bilinear $⟨\overline{\psi }\psi ⟩$ in a spatially flat Friedmann-Lemaitre-Robertson-Walker (FLRW) spacetime. These are basic ingredients in the semiclassical field equations of fermionic matter in curved spacetime interacting with a background scalar field. The ultraviolet subtracting terms of the adiabatic regularization can be naturally interpreted as coming from appropriate counterterms of the background fields. We fix the required covariant counterterms. To test our approach we determine the contribution of the Yukawa interaction to the conformal anomaly in the massless limit and show its consistency with the heat-kernel method using the effective action.

We derive the 1–loop effective action of the cubic Galileon coupled to quantum-gravitational fluctuations in a background and gauge-independent manner, employing the covariant framework of DeWitt and Vilkovisky. Although the bare action respects shift symmetry, the coupling to gravity induces an effective mass to the scalar, of the order of the cosmological constant, as a direct result of the nonflat field–space metric, the latter ensuring the field-reparametrization invariance of the formalism. Within a gauge-invariant regularization scheme, we discover novel, gravitationally induced non-Galileon higher-derivative interactions in the effective action. These terms, previously unnoticed within standard, noncovariant frameworks, are not Planck suppressed. Unless tuned to be subdominant, their presence could have important implications for the classical and quantum phenomenology of the theory.

It is well known that by interpreting the cosmological constant as the pressure, the anti–de Sitter black holes behave as the van der Waals thermodynamic system. In this case, like a phase transition from vapor to liquid in a usual van der Waals system, black holes also change phases about a critical point in the $P\text{−}V$ picture, where $P$ is the pressure and $V$ is the thermodynamic volume. Here, we give a geometrical description of this phase transition. Defining the relevant Legendre-invariant thermogeometrics corresponding to the two criticality conditions, which determine the critical values of respective thermodynamical entities, we show that the critical point refers to the divergence of the Ricci scalars calculated from these metrics. The similar descriptions are also provided for the other two pictures of the van der Waals like phase transition: one is $T\text{−}S$ and the other one is $Y\text{−}X$ where $T$, $S$, $X$ and $Y$ are temperature, entropy, generalized force and generalized displacement (i.e. potential corresponding to external charge, respectively). The whole discussion is very general as no specific black-hole metric is being used.

We present the first surrogate model for gravitational waveforms from the coalescence of precessing binary black holes. We call this surrogate model NRSur4d2s. Our methodology significantly extends recently introduced reduced-order and surrogate modeling techniques, and is capable of directly modeling numerical relativity waveforms without introducing phenomenological assumptions or approximations to general relativity. Motivated by GW150914, LIGO’s first detection of gravitational waves from merging black holes, the model is built from a set of 276 numerical relativity (NR) simulations with mass ratios $q\le 2$, dimensionless spin magnitudes up to 0.8, and the restriction that the initial spin of the smaller black hole lies along the axis of orbital angular momentum. It produces waveforms which begin $\sim 30$ gravitational wave cycles before merger and continue through ringdown, and which contain the effects of precession as well as all $\ell \in \{2,3\}$ spin-weighted spherical-harmonic modes. We perform cross-validation studies to compare the model to NR waveforms not used to build the model and find a better agreement within the parameter range of the model than other, state-of-the-art precessing waveform models, with typical mismatches of ${10}^{-3}$. We also construct a frequency domain surrogate model (called NRSur4d2s_FDROM) which can be evaluated in 50 ms and is suitable for performing parameter estimation studies on gravitational wave detections similar to GW150914.

It has been shown that gravitational waves propagate through ideal fluids without experiencing any dispersion or dissipation. However, if the medium has a nonzero shear viscosity $\eta$, gravitational waves will be dissipated at a rate proportional to $G\eta$. We constrain dark matter and dark energy models with nonzero shear viscosity by calculating the dissipation of gravitational waves from GW150914 which propagate over a distance of 410 Mpc through the dissipative fluid and comparing the data with the theoretical prediction. This provides a proof-of-principle demonstration of the fact that future observations gravitational waves at LIGO have the potential of better constraining the viscosity of dark matter and dark energy.

We study the Unruh Effect for a wide class of nonlocal theories. Using the approach of Bogoliubov coefficients, we show that the Unruh Effect remains entirely unmodified in these theories. However, for those nonlocal theories which incorporate a minimal length, the approach using Unruh-DeWitt detectors predicts a modification in the Unruh Effect. Previous work shows that this modification may even be drastic. This appears contradictory with two apparently equivalent methods giving different results. We investigate the origin of the contradiction and show that for these theories, the two methods are indeed inequivalent. We argue that the detector method incorporates an assumption of local interaction that does not hold for nonlocal theories, and, therefore, the method of Bogoliubov coefficients is preferable.

In order to avoid unphysical causality-violating effects, any rigidly rotating system must be bounded in directions transverse to the axis of rotation. We demonstrate that this requirement implies substantial dependence of properties of the relativistically rotating system on the boundary conditions. We consider a system of interacting fermions described by the Nambu–Jona-Lasinio model in a space bounded by the cylindrical surface of the finite radius. In order to confine the fermions inside the cylinder, we impose “chiral” MIT boundary conditions on its surface. These boundary conditions are parametrized by a continuous chiral angle $\mathrm{\Theta }$. We find that, at any value of $\mathrm{\Theta }$, the chiral restoration temperature $T_c$ decreases as a quadratic function of the angular frequency $\mathrm{\Omega }$. However, the position and the slope of the critical curve $T_c=T_c(\mathrm{\Omega })$ in the phase diagram depend noticeably on the value of the chiral angle.

We study the possibility of radiative electroweak symmetry breaking where loop corrections to the mass parameter of the Higgs boson trigger the symmetry breaking in various extensions of the Standard Model (SM). Although the mechanism fails in the SM, it is shown to be quite successful in several extensions which share a common feature of having an additional scalar around the TeV scale. The positive Higgs mass parameter at a high energy scale is turned negative in the renormalization group flow to lower energy by the cross couplings between the scalars in the Higgs potential. The type-II seesaw model with a TeV scale weak scalar triplet, a two-loop radiative neutrino mass model with new scalars at the TeV scale, the inert doublet model, scalar singlet dark matter model, and a universal seesaw model with an additional $U(1)$ broken at the TeV scale are studied and shown to exhibit successful radiative electroweak symmetry breaking.

We analyze, within several parameter scenarios of type-II two-Higgs doublet extensions of the standard model, the impact of heavy neutral Higgs-boson resonances on top-quark pair production and their subsequent decay to dileptonic final states at the LHC (13 TeV). In particular, we investigate the effects of heavy Higgs bosons on top-spin observables, that is, the longitudinal top-quark polarization and top-quark spin correlations. We take into account NLO QCD as well as weak interaction corrections and show that top-spin observables, if evaluated in judiciously chosen top-quark pair invariant mass bins, can significantly enhance the sensitivity to heavy Higgs resonances in top-quark pair events.

In this paper, we investigate the conserved charges of generally diffeomorphism invariant gravity theories with a wide variety of matter fields, particularly of the theories with multiple scalar fields and $p$-form potentials, in the context of the off-shell generalized Abbott-Deser-Tekin (ADT) formalism. We first construct a new off-shell ADT current that consists of the terms for the variation of a Killing vector and expressions of the field equations as well as the Lie derivative of a surface term with respect to the Killing vector within the framework of generally diffeomorphism invariant gravity theories involving various matter fields. After deriving the off-shell ADT potential corresponding to this current, we propose a formula of conserved charges for these theories. Next, we derive the off-shell ADT potential associated with the generic Lagrangian that describes a large range of gravity theories with a number of scalar fields and $p$-form potentials. Finally, the properties of the off-shell generalized ADT charges for the theory of Einstein gravity and the gravity theories with a single $p$-form potential are investigated by performing Kaluza-Klein dimensional reduction along a compactified direction. The results indicate that the charge contributed by all the fields in the lower-dimensional theory is equal to that of the higher-dimensional one at mathematical level with the hypothesis that the higher-dimensional spacetime allows for the existence of the compactified dimension. In order to illustrate our calculations, the mass and angular momentum for the five-dimensional rotating Kaluza-Klein black holes are explicitly evaluated as an example.

We discuss the geodesic motion of both massive test particles, following timelike geodesics, and light, following null geodesics, on Finsler spacetimes with cosmological symmetry. Using adapted coordinates on the tangent bundle of the spacetime manifold, we derive the general form of the geodesic equation. Further, we derive a complete set of constants of motion. As an application of these findings, we derive the magnitude-redshift relation for light propagating on a cosmologically symmetric Finsler background, both for a general Finsler spacetime and for particular examples, such as spacetimes equipped with Bogoslovsky and Randers length measures. Our results allow a confrontation of these geometries with observations of the magnitude and redshift of supernovae.

We show a simple, systematic and direct approach to decoupling gravitational sources in general relativity. As a direct application, a robust and simple way to generate anisotropic solutions for self-gravitating systems from perfect fluid solutions is presented.