Chiral tensors of mixed Young symmetry, which exist in the same spacetime dimensions $2+4n$ where chiral $p$ forms can be defined, are investigated. Such chiral tensors have been argued to play a central role in exotic formulations of gravity in six dimensions and possess intriguing properties. A variational principle that yields the chiral equations of motion is explicitly constructed and related to the action for a nonchiral tensor. The use of prepotentials turns out to be essential in our analysis. We also comment on dimensional reduction.

Thermal inflation driven by a scalar field called a “flaton” is a possible scenario to solve the cosmological moduli problem. We study a model of thermal inflation with a flaton chemical potential. In the presence of the chemical potential, a negative mass squared of the flaton—which is necessary to terminate thermal inflation—is naturally induced. We identify the allowed parameter region for the chemical potential ($\mu$) and the flaton self-coupling constant to solve the cosmological moduli problem and satisfy theoretical consistencies. In general, the chemical potential is a free parameter and it can be taken to be much larger than the typical scale of soft supersymmetry-breaking parameters of $\mathcal{O}(1)\mathrm{TeV}$. For $\mu \gtrsim 10^8\mathrm{GeV}$, we find that the reheating temperature after thermal inflation can be high enough for the thermal leptogenesis scenario to be operative. This is in sharp contrast to the standard thermal inflation scenario, in which the reheating temperature is quite low and a special mechanism is necessary for generating a sufficient amount of baryon asymmetry in the Universe after thermal inflation.

In many generalized models of gravity, perfect fluids in cosmology give rise to gravitational slip. Simultaneously, in very broad classes of such models, the propagation of gravitational waves is altered. We investigate the extent to which there is a one-to-one relationship between these two properties in three classes of models with one extra degree of freedom: scalar (Horndeski and beyond), vector (Einstein-aether), and tensor (bimetric). We prove that in bimetric gravity and Einstein-aether, it is impossible to dynamically hide the gravitational slip on all scales whenever the propagation of gravitational waves is modified. Horndeski models are much more flexible, but it is nonetheless only possible to hide gravitational slip dynamically when the action for perturbations is tuned to evolve in time toward a divergent kinetic term. These results provide an explicit, theoretical argument for the interpretation of future observations if they disfavored the presence of gravitational slip.

Magnetic monopoles are suggested to play an important role in strongly coupled quark-gluon plasma (sQGP) near the deconfinement temperature. Until now, their many-body treatment has been studied classically; only their binary scattering has been solved in quantum mechanics. In this paper we start quantum many-body studies of the monopole ensembles. Specifically, we carry out numerical simulations of the path integral for one- and two-component Coulomb Bose systems. We determine the relation between the critical temperature for the Bose-Einstein condensation phase transition $T_{\mathrm{c}}$ and the Coulomb coupling strength using two methods, the classic finite-size scaling of the condensate and a lattice-tested method based on permutation cycles. For a one-component Coulomb Bose gas, we observe the same behavior of the critical temperature—initially rising slightly, then falling as interaction strength is increased—as seen in the case of hard spheres; we also observe the same behavior for a two-component Coulomb Bose gas. We then calculate sets of radial correlation functions between the like and unlike charged particles. By matching these with the correlation functions previously calculated on the lattice, we derive an effective quantum model of color magnetic monopoles in QCD. From this matched model, we are able to extract the monopole contribution to the QCD equation of state near $T_{\mathrm{c}}$.

By considering that the weak currents and the electromagnetic current are members of the same $SU(3)$ octet, two sum rules involving leading vector form factors in hyperon semileptonic decays are derived in the limit of exact flavor $SU(3)$ symmetry. Deviations from this limit arise from second-order $SU(3)$ symmetry-breaking effects, according to the Ademollo-Gatto theorem. The $1/N_c$ expansion of QCD is used to evaluate such effects. One sum rule vanishes identically even in the presence of symmetry breaking and the other one obtains contributions mainly from the $\mathbf{10}+\overline{\mathbf{10}}$ representation. Results obtained in (heavy) baryon chiral perturbation theory are used to test the validity of these sum rules. To order $\mathcal{O}(p^2)$ in the chiral expansion, results are encouraging.

We show how to evaluate one-dimensional Minkowski-region Mellin-Barnes representations arising from massive loop integrals, by modifying the contours of integration. We implement an exact solution to the differential equation determining the contours of stationary phase. We also present several simple approximations to these contours. Our approach points the way to more efficient computations of massless and massive Mellin-Barnes integrals in both Euclidean and Minkowski regions.

We study the left-right asymmetric model based on the $SU(3{)}_C\otimes SU(2{)}_L\otimes SU(3{)}_R\otimes U(1{)}_X$ gauge group, which improves the theoretical and phenomenological aspects of the known left-right symmetric model. This new gauge symmetry yields that the fermion generation number is 3, and the tree-level flavor-changing neutral currents arise in both gauge and scalar sectors. Also, it can provide the observed neutrino masses, as well as dark matter, automatically. Further, we investigate the mass spectrum of the gauge and scalar fields. All the gauge interactions of the fermions and scalars are derived. We examine the tree-level contributions of the new neutral vector, $Z_R^{\prime }$, and new neutral scalar, $H_2$, to flavor-violating neutral meson mixings, say $K-\overline{K}$, $B_d-{\overline{B}}_d$, and $B_s-{\overline{B}}_s$, which strongly constrain the new physics scale as well as the elements of the right-handed quark mixing matrices. The bounds for the new physics scale are in agreement with those coming from the $\rho$-parameter, as well as the mixing parameters between $W$, $Z$ bosons and new gauge bosons.

By applying chiral-perturbation-theory methods to the QCD sector of the Lorentz-violating Standard-Model Extension, we investigate Lorentz violation in the strong interactions. In particular, we consider the $CPT$-even pure-gluon operator of the minimal Standard-Model Extension. We construct the lowest-order chiral effective Lagrangian for three as well as two light quark flavors. We develop the power-counting rules and construct the heavy-baryon chiral-perturbation-theory Lagrangian, which we use to calculate Lorentz-violating contributions to the nucleon self-energy. Using the constructed effective operators, we derive the first stringent limits on many of the components of the relevant Lorentz-violating parameter. We also obtain the Lorentz-violating nucleon-nucleon potential. We suggest that this potential may be used to obtain new limits from atomic-clock or deuteron storage-ring experiments.

The electron self-energy and anomalous magnetic moment in ($2+1$) QED with a Chern-Simons term are investigated at finite temperature and density in an external magnetic field. In the limiting case of a relatively weak magnetic field, the exact expression for the vacuum anomalous magnetic moment (AMM) has been found at zero temperature and density of the medium. The energy shift and AMM of an electron are analyzed as a function of the temperature and Chern-Simons parameter in the charge-symmetric case. We obtained the new asymptotic expression for the AMM in the high-temperature region. The electron AMM has been calculated also in the case of a completely degenerate magnetized electron gas.

Tensor-polarized structure functions of a spin-1 hadron are additional observables, which do not exist for the spin-$1/2$ nucleon. They could probe novel aspects of the internal hadron structure. Twist-2 tensor-polarized structure functions are $b_1$ and $b_2$, and they are related by the Callan-Gross-like relation in the Bjorken scaling limit. In this work, we theoretically calculate $b_1$ in the standard convolution description for the deuteron. Two different theoretical models, a basic convolution description and a virtual nucleon approximation, are used for calculating $b_1$, and their results are compared with the HERMES measurement. We found large differences between our theoretical results and the data. Although there is still room to improve by considering higher-twist effects and in the experimental extraction of $b_1$ from the spin asymmetry $A_{zz}$, there is a possibility that the large differences require physics beyond the standard deuteron model for their interpretation. Future $b_1$ studies could shed light on a new field of hadron physics. In particular, detailed experimental studies of $b_1$ will start soon at the Thomas Jefferson National Accelerator Facility. In addition, there are possibilities to investigate tensor-polarized parton distribution functions and $b_1$ at Fermi National Accelerator Laboratory and a future electron-ion collider. Therefore, further theoretical studies are needed for understanding the tensor structure of the spin-1 deuteron, including a new mechanism to explain the large differences between the current data and our theoretical results.

We extend a known multiquark three-flavor Lagrangian of the Nambu-Jona-Lasinio type, which includes a set of effective interactions proportional to the current quark masses, to include the multiquark interactions of vector and axial-vector types. It is shown that the mass spectrum of the four low-lying meson nonets are in agreement with current phenomenological expectations. The role of the new interactions is analyzed in detail.

The $B_c^{*}\to B_{u,d,s}V$, $B_{u,d,s}P$ decays are investigated with the QCD factorization approach, where $V$ and $P$ denote the ground $SU(3)$ vector and pseudoscalar mesons, respectively. The $B_c^{*}\to B_{u,d,s}$ transition form factors are calculated with the Wirbel-Stech-Bauer model. It is found that branching ratios for the color-favored and Cabibbo-favored $B_c^{*}\to B_s\rho$, $B_s\pi$ decays can reach up to $\mathcal{O}({10}^{-7})$, which might be measurable in the future LHC experiments.

In this work, we investigate the possibility of interpreting two nucleon resonances, the $N(1875)$ and the $N(2100)$, as hadronic molecular states from the ${\mathrm{\Sigma }}^{*}K$ and $\mathrm{\Sigma }{K}^{*}$ interactions, respectively. With the help of effective Lagrangians in which coupling constants are determined by the SU(3) symmetry, the ${\mathrm{\Sigma }}^{*}K$ and $\mathrm{\Sigma }{K}^{*}$ interactions are described by the vector-meson and pseudoscalar-meson exchanges. With the one-boson-exchange potential obtained, bound states from the ${\mathrm{\Sigma }}^{*}K$ and $\mathrm{\Sigma }{K}^{*}$ interactions are searched for in a quasipotential Bethe-Saltpeter equation approach. A bound state with quantum number $I(J^P)=1/2(3/2^{-})$ is produced from the ${\mathrm{\Sigma }}^{*}K$ interaction, which can be identified as the $N(1875)$ listed in PDG. It can be seen as a strange partner of the LHCb pentaquark $P_c(4380)$ with the same quantum numbers in the molecular state picture. The $\mathrm{\Sigma }{K}^{*}$ interaction also produces a bound state with quantum number $I(J^P)=1/2(3/2^{-})$, which is related to experimentally observed $N(2100)$ in the $\varphi$ photoproduction. Our results suggest that the $N(2120)$ observed in the $K\mathrm{\Lambda }(1520)$ photoproduction and the $N(2100)$ observed in the $\varphi$ photoproduction have different origins. The former is a conventional three-quark state while the latter is a $\mathrm{\Sigma }{K}^{*}$ molecular state, which can be seen as a strange partner of the $P_c(4450)$ with different spin parity.

Using an electron-positron collision data sample of $2.93{\mathrm{fb}}^{-1}$ collected at a center-of-mass energy of $\sqrt{s}=3.773\mathrm{GeV}$ with the BESIII detector, we present the first search for the radiative leptonic decay $D^{+}\to \gamma e^{+}{\nu }_e$. The analysis is performed with a double-tag method. We do not observe a significant $D^{+}\to \gamma e^{+}{\nu }_e$ signal, and obtain an upper limit on the branching fraction of $D^{+}\to \gamma e^{+}{\nu }_e$ decay with the energy of radiative photon larger than 10 MeV of $3.0\times {10}^{-5}$ at the 90% confidence level.

Holographic entanglement entropies (HEE) associated with four-dimensional Schwarzschild and Reisner-Nordström (RN) black holes in asymptotically Minkowski spacetimes are investigated. Unlike the cases of asymptotically AdS spacetimes for which the boundaries are always taken at (timelike) conformal infinities, we take the boundaries at either large but finite radial coordinates (far boundary) or very close to the black hole event horizons (near horizon boundary). The reason for such choices is that such boundaries are similar to the conformal infinity of AdS spacetime in that they are all timelike, so that there may be some hope to define dual systems with ordinary time evolution on such boundaries. Our results indicate that, in the case of far boundaries, the leading-order contribution to HEEs comes from the background Minkowski spacetime; however, the next-to-leading-order contribution which arises from the presence of the black holes is always proportional to the black hole mass, which constitutes a version of the first law of HEE for asymptotically flat spacetimes, and the higher-order contributions are always negligibly small. In the case of near horizon boundaries, the leading-order contribution to HEE is always proportional to the area of the black hole event horizon, and the case of extremal RN black holes is distinguished from the cases of nonextremal black holes in that the minimal surface defining HEE is completely immersed inside the boundary up to the second order in the perturbative expansion.

We study the effect of a Chern-Simons term on the electrically charged and spinning solitons of several $U(1)$ gauged models in $2+1$ dimensions. These are vortices of complex scalar field theories, both with and without symmetry breaking dynamics, and the $O(3)$ Skyrme model. In all cases the gauge decoupling limits are also considered. It is well known that the effect of the Chern-Simons dynamics is to endow vortices with electric charge $Q_e$ and spin $J$, but our main aim here is to reveal a new feature: that the mass-energy $E$ of the electrically charged vortex can be lower than that of the electrically neutral one, in contrast to the usual monotonic increase of $E$ with $Q_e$ and $J$. These effects of Chern-Simons dynamics were observed previously in $3+1$ dimensional systems, and the present results can be viewed as corroborating the latter. We carry out a detailed quantitative analysis of azimuthally symmetric vortices and describe their qualitative features by constructing the solutions numerically.

We study the role of field redefinitions in general scalar-tensor theories. In particular, we first focus on the class of field redefinitions linear in the spin-2 field and involving derivatives of the spin-0 mode, generically known as disformal transformations. We start by defining the action of a disformal transformation in the tangent space. Then, we take advantage of the great economy of means of the language of differential forms to compute the full transformation of Horndeski’s theory under general disformal transformations. We obtain that Horndeski’s action maps onto itself modulo a reduced set of non-Horndeski Lagrangians. These new Lagrangians are found to be invariant under disformal transformation that depend only in the first derivatives of the scalar. Moreover, these combinations of Lagrangians precisely appear when expressing in our basis the constraints of the recently proposed extended scalar-tensor theories. These results allow us to classify the different orbits of scalar-tensor theories invariant under particular disformal transformations, namely, the special disformal, kinetic disformal, and disformal Horndeski orbits. In addition, we consider generalizations of this framework. We find that there are possible well-defined extended disformal transformations that have not been considered in the literature. However, they generically cannot link Horndeski theory with extended scalar-tensor theories. Finally, we study further generalizations in which extra fields with different spin are included. These field redefinitions can be used to connect different gravity theories such as multiscalar-tensor theories, generalized Proca theories, and bigravity. We discuss how the formalism of differential forms could be useful for future developments in these lines.

We present the asymptotic solutions for spacetimes with nonzero cosmological constant $\mathrm{\Lambda }$ coupled to Maxwell fields, using the Newman-Penrose formalism. This extends a recent work that dealt with the vacuum Einstein (Newman-Penrose) equations with $\mathrm{\Lambda }\ne 0$. The results are given in two different null tetrads: the Newman-Unti and Szabados-Tod null tetrads, where the peeling property is exhibited in the former but not the latter. Using these asymptotic solutions, we discuss the mass loss of an isolated electrogravitating system with cosmological constant. In a universe with $\mathrm{\Lambda }>0$, the physics of electromagnetic (EM) radiation is relatively straightforward compared to those of gravitational radiation: (1) It is clear that outgoing EM radiation results in a decrease to the Bondi mass of the isolated system. (2) It is also perspicuous that if any incoming EM radiation from elsewhere is present, those beyond the isolated system’s cosmological horizon would eventually arrive at the spacelike $\mathcal{I}$ and increase the Bondi mass of the isolated system. Hence, the (outgoing and incoming) EM radiation fields do not couple with $\mathrm{\Lambda }$ in the Bondi mass-loss formula in an unusual manner, unlike the gravitational counterpart where outgoing gravitational radiation induces nonconformal flatness of $\mathcal{I}$. These asymptotic solutions to the Einstein–Maxwell–de Sitter equations presented here may be used to extend a raft of existing results based on Newman-Unti’s asymptotic solutions to the Einstein-Maxwell equations where $\mathrm{\Lambda }=0$, to now incorporate the cosmological constant $\mathrm{\Lambda }$.

We construct regular rotating black hole and no-horizon spacetimes based on the recently introduced spherically symmetric generic regular black hole spacetimes related to electric or magnetic charge under nonlinear electrodynamics coupled to general relativity that for special values of the spacetime parameters reduce to the Bardeen and Hayward spacetimes. We show that the weak and strong energy conditions are violated inside the Cauchy horizons of these generic rotating black holes. We give the boundary between the rotating black hole and no-horizon spacetimes and determine the black hole horizons and the boundary of the ergosphere. We introduce the separated Carter equations for the geodesic motion in these rotating spacetimes. For the most interesting new class of the regular spacetimes, corresponding for magnetic charges to the Maxwell field in the weak field limit of the nonlinear electrodynamics, we determine the structure of the circular geodesics and discuss their properties. We study the epicyclic motion of a neutral particle moving along the stable circular orbits around the “Maxwellian” rotating regular black holes. We show that epicyclic frequencies measured by the distant observers and related to the oscillatory motion of the neutral test particle along the stable circular orbits around the rotating singular and regular Maxwellian black holes are always smaller than ones in the Kerr spacetime.

Banados, Teitelboim, and Zanelli (BTZ) black holes are excellent laboratories for studying black hole thermodynamics, which is a bridge between classical general relativity and the quantum nature of gravitation. In addition, three-dimensional gravity could have equipped us for exploring some of the ideas behind the two-dimensional conformal field theory based on the ${\mathrm{AdS}}_3/{\mathrm{CFT}}_2$. Considering the significant interest in these regards, we examine charged BTZ black holes. We consider the system contains massive gravity with energy dependent spacetime to enrich the results. In order to make high curvature (energy) BTZ black holes more realistic, we modify the theory by energy dependent constants. We investigate thermodynamic properties of the solutions by calculating heat capacity and free energy. We also analyze thermal stability and study the possibility of the Hawking-Page phase transition. At last, we study the geometrical thermodynamics of these black holes and compare the results of various approaches.