The predictions of standard Higgs inflation in the framework of the metric formalism yield a tensor-to-scalar ratio $r\sim {10}^{-3}$ which lies well within the expected accuracy of near-future experiments $\sim {10}^{-4}$. When the Palatini formalism is employed, the predicted values of $r$ get highly suppressed $r\sim {10}^{-12}$ and consequently a possible nondetection of primordial tensor fluctuations will rule out only the metric variant of the model. On the other hand, the extremely small values predicted for $r$ by the Palatini approach constitute contact with observations a hopeless task for the foreseeable future. In this work, we propose a way to remedy this issue by extending the action with the inclusion of a generalized nonminimal derivative coupling term between the inflaton and the Einstein tensor of the form $m^{-2}(\varphi )G_{\mu \nu }{\nabla }^{\mu }\varphi {\nabla }^{\nu }\varphi$. We find that with such a modification, the Palatini predictions can become comparable with the ones obtained in the metric formalism, thus providing ample room for the model to be in contact with observations in the near future.

Dwarf spheroidal galaxies that form in halo substructures provide stringent constraints on dark matter annihilation. Many ultrafaint dwarfs discovered with modern surveys contribute significantly to these constraints. At present, because of the lack of abundant stellar kinematic data for the ultrafaints, noninformative prior assumptions are usually made for the parameters of the density profiles. Based on semianalytic models of dark matter subhalos and their connection to satellite galaxies, we present more informative and realistic satellite priors. We show that our satellite priors lead to constraints on the annihilation rate that are between a factor of 2 and a factor of 7 weaker than under noninformative priors. As a result, the thermal relic cross section can at best only be excluded (with 95% probability) for dark matter masses of $\lesssim 40\mathrm{GeV}$ from dwarf spheroidal data, assuming annihilation into $b\overline{b}$.

We study the relaxation time required for the alignment between the spin of a finite-mass quark or antiquark and the thermal vorticity, at finite temperature and baryon chemical potential, in the context of relativistic heavy-ion collisions. The relaxation time is computed as the inverse of the total reaction rate that in turn is obtained from the imaginary part of the quark or antiquark self-energy. We model the interaction between spin and thermal vorticity within the medium by means of a vertex coupling quarks and thermal gluons that, for a uniform temperature, is proportional to the global angular velocity and inversely proportional to the temperature. We use realistic estimates for the angular velocities for different collision energies and show that the effect of the quark mass is to reduce the relaxation times as compared to the massless quark case. Using these relaxation times we estimate the intrinsic quark and antiquark polarizations produced by the thermal vorticity. We conclude by pointing out that, although the intrinsic global polarization of the $s$-quark turns out to be larger than that of the $\overline{s}$-quark, there is room to explain recent STAR results which show that the global polarization of $\overline{\mathrm{\Lambda }}$ is larger than that of $\mathrm{\Lambda }$ when considering that these hyperons can be produced from different density regions in a core-corona model.

Within the chiral unitary approach and with the constraints of heavy quark spin symmetry, we study the coupled channel interactions of ${\overline{D}}^{(*)}{\mathrm{\Sigma }}_c^{(*)}$ channels, close to whose thresholds three pentaquarklike $P_c$ states have been reported by the LHCb Collaboration. In the present work, we take into account the contributions of pion exchanges via box diagrams to the interaction potentials, and therefore lift the degeneracy in the masses of ${\overline{D}}^{*}{\mathrm{\Sigma }}_c^{(*)}$ spin multiplets. Fitting the $J/\psi p$ invariant mass distributions in the ${\mathrm{\Lambda }}_b^0\to J/\psi K^{-}p$ decay, we find that the LHCb pentaquark states cannot be reproduced in the direct $J/\psi p$ production in the ${\mathrm{\Lambda }}_b^0$ decay, and can only be indirectly produced in the final state interactions of the ${\mathrm{\Lambda }}_b^0$ decay products, ${\overline{D}}^{(*)}{\mathrm{\Sigma }}_c^{(*)}$, which further supports the nature of these states as ${\overline{D}}^{(*)}{\mathrm{\Sigma }}_c$ molecules. Based on the fit results obtained, we study the partial decay widths/branching ratios to the other decay channels, ${\overline{D}}^{*}{\mathrm{\Lambda }}_c$, $\overline{D}{\mathrm{\Lambda }}_c$, and ${\eta }_{c}N$, and the corresponding invariant mass distributions. The resonances with $J^P={\frac{1}{2}}^{-}$, $P_c(4312)$, $P_c(4440)$ and the one of ${\overline{D}}^{*}{\mathrm{\Sigma }}_c^{*}$ around 4500 MeV, have large partial decay width into ${\eta }_{c}N$, and thus can be easily seen in the ${\eta }_{c}N$ invariant mass distributions. By contrast, the states with $J^P={\frac{3}{2}}^{-}$, $P_c(4457)$, the (predicted) narrow $P_c(4380)$, and the bound state of ${\overline{D}}^{*}{\mathrm{\Sigma }}_c^{*}$ with a mass of about 4520 MeV do not decay into ${\eta }_{c}N$. Therefore, the ${\eta }_{c}N$ channel should be studied in the future to provide further insights into the nature of these states, especially that of $P_c(4440)$ and $P_c(4457)$.

In this work, we study the $S$, $P$, and $D$ wave resonance contributions to three-body decays $B_{(s)}\to [D^{(*)},{\overline{D}}^{(*)}]K^{+}{K}^{-}$ by employing the perturbative QCD (PQCD) approach, where the kaon-kaon invariant mass spectra are dominated by the $f_0(980)$, $f_0(1370)$, $\varphi (1020)$, $\varphi (1680)$, $f_2(1270)$, $f_2^{\prime }(1525)$, $f_2(1750)$, and $f_2(1950)$ resonances. The $KK$ $S$-wave component $f_0(980)$ is modeled with the Flatté formalism, while other resonances are described by the relativistic Breit-Wigner line shape. The corresponding decay channels are studied by constructing the kaon-kaon distribution amplitude ${\mathrm{\Phi }}_{KK}$, which captures important final state interactions between the kaon pair in the resonant region. We found that the PQCD predictions for the branching ratios for most considered decays agree with currently available data within errors. The associated polarization fractions of those vector-vector and vector-tensor decay modes are also predicted, which are expected to be tested in the near future experiments. The invariant mass spectra for the corresponding resonances in the $B_{(s)}\to [D^{(*)},{\overline{D}}^{(*)}]K^{+}{K}^{-}$ decays are well established, which can be confronted with the precise data from the LHCb and Belle II experiments.

The search for di-Higgs final states is typically limited at the LHC to the dominant gluon fusion channels, with weak boson fusion only assuming a spectator role. In this work, we demonstrate that when it comes to searches for resonant structures that arise from isosinglet mixing in the Higgs sector, the weak boson fusion sideline can indeed contribute to winning the discovery game. Extending existing experimental resonance searches by including both contributions is therefore crucial.

We show how to formulate a lattice gauge theory whose naive continuum limit corresponds to two-dimensional (Euclidean) quantum gravity including a positive cosmological constant. More precisely the resultant continuum theory corresponds to gravity in a first-order formalism in which the local frame and spin connection are treated as independent fields. Recasting this lattice theory as a tensor network allows us to study the theory at strong coupling without encountering a sign problem. In two dimensions this tensor network is exactly soluble and we show that the system has a series of critical points that occur for pure imaginary coupling and are associated with first order phase transitions. We then augment the action with a Yang-Mills term which allows us to control the lattice spacing and show how to apply the tensor renormalization group to compute the free energy and look for critical behavior. Finally we perform an analytic continuation in the gravity coupling in this extended model and show that its critical behavior in a certain scaling limit depends only on the topology of the underlying lattice. We also show how the lattice gauge theory can be naturally generalized to generate the Polyakov or Liouville action for two dimensional quantum gravity.

The power corrections in the operator product expansion (OPE) of QCD correlators can be viewed mathematically as an illustration of the transseries concept, which allows us to recover a function from its asymptotic divergent expansion. Alternatively, starting from the divergent behavior of the perturbative QCD encoded in the singularities in the Borel plane, a modified expansion can be defined by means of the conformal mapping of this plane. A comparison of the two approaches concerning their ability to recover nonperturbative properties of the true correlator was not explored up to now. In the present paper, we make a first attempt to investigate this problem. We use for illustration the Adler function and observables expressed as integrals of this function along contours in the complex energy plane. We show that the expansions based on the conformal mapping of the Borel plane go beyond finite-order perturbation theory, containing an infinite number of terms when reexpanded in powers of the coupling. Moreover, the expansion functions exhibit nonperturbative features of the true function, while the expansions have a tamed behavior at large orders and are expected even to be convergent. Using these properties, we argue that there are no mathematical reasons for supplementing the expansions based on the conformal mapping of the Borel plane by additional arbitrary power corrections. Therefore, we make the conjecture that they provide an alternative to the standard OPE in approximating the QCD correlator. This conjecture allows to slightly improve the accuracy of the strong coupling extracted from the hadronic $\tau$ decay width. Using the optimal expansions based on conformal mapping and the contour-improved prescription of renormalization-group resummation, we obtain ${\alpha }_s(m_{\tau }^2)=0.314\pm 0.006$, which implies ${\alpha }_s(m_Z^2)=0.1179\pm 0.0008$.

We report on an analysis of the decay $J/\psi \to \gamma {\pi }^0{\eta }^{\prime }$ using a sample of $(1310.6\pm 7.0)\times {10}^{6}J/\psi$ events collected with the BESIII detector. We search for the $CP$-violating process ${\eta }_c\to {\pi }^0{\eta }^{\prime }$ and a dark gauge boson $U^{\prime }$ in $J/\psi \to U^{\prime }{\eta }^{\prime },U^{\prime }\to \gamma {\pi }^0,{\pi }^0\to \gamma \gamma$. No evidence of an ${\eta }_c$ signal is observed in the ${\pi }^0{\eta }^{\prime }$ invariant-mass spectrum and the upper limit of the branching fraction is determined to be $5.6\times {10}^{-5}$ at the 90% confidence level. We also find no evidence of $U^{\prime }$ production and set upper limits at the 90% confidence level on the product branching fraction $\mathcal{B}(J/\psi \to U^{\prime }{\eta }^{\prime })\times \mathcal{B}(U^{\prime }\to {\pi }^0\gamma )$ in the range between $(0.8-6.5)\times {10}^{-7}$ for $0.2\le m_{U^{\prime }}\le 2.1\mathrm{GeV}/c^2$. In addition, we study the process $J/\psi \to \omega {\eta }^{\prime }$ with $\omega \to \gamma {\pi }^0$. The branching fraction of $J/\psi \to \omega {\eta }^{\prime }$ is found to be $(1.87\pm 0.09\pm 0.12)\times {10}^{-4}$, where the first uncertainty is statistical and the second is systematic, with a precision that is improved by a factor of 1.4 over the previously published BESIII measurement.

We extend the stability analysis of the configurations under finite strain using Effective Field Theory (EFT) methods done in [L. Alberte, M. Baggioli, V. C. Castillo, and O. Pujolas, Phys. Rev. D 100, 065015 (2019)]. At finite strain the medium is anisotropic and so fluctuations in different directions behave differently. We recompute the bounds by including the instabilities that may occur in all possible directions. Qualitatively, the main conclusions of [Phys. Rev. D 100, 065015 (2019)] remain unchanged: Nontrivial bounds and correlations between different nonlinear observables can be obtained using EFT methods. Quantitatively, the bounds become more stringent—especially so for materials with power-law stress strain curves ($\sigma \sim {ϵ}^{\nu }$) characterized with a small exponent $\nu$.

For the first time, a gravitational calculation was recently shown to yield the Page curve for the entropy of Hawking radiation, consistent with unitary evolution. However, the calculation takes as essential input Hawking’s result that the radiation entropy becomes large at late times. We call this apparent contradiction the state paradox. We exhibit its manifestations in standard and doubly holographic settings, with and without an external bath. We clarify which version(s) of the Ryu-Takayanagi prescription apply in each setting. We show that the two possible homology rules in the presence of a braneworld generate a bulk dual of the state paradox. The paradox is resolved if the gravitational path integral computes averaged quantities in a suitable ensemble of unitary theories, a possibility supported independently by several recent developments.

We develop a method for treating a series of secularly growing terms obtained from quantum perturbative calculations: autonomous first-order differential equations are constructed such that they reproduce this series to the given order. The exact solutions of these equations are free of secular terms and approach a finite limit at late times. This technique is illustrated for the well-known problem of secular growth of correlation functions of a massless scalar field with a quartic self-interaction in de Sitter space. For the expectation value of the product of two fields at coinciding space-time points, we obtain a finite late-time result that is very close to the one following from Starobinsky’s stochastic approach.

Smirnov and Zamolodchikov recently introduced a new class of two-dimensional quantum field theories, defined through a differential change of any existing theory by the determinant of the energy-momentum tensor. From this $T\overline{T}$ flow equation one can find a simple expression for both the energy spectrum and the $S$-matrix of the $T\overline{T}$ deformed theories. Our goal is to find the renormalized Lagrangian of the $T\overline{T}$ deformed theories. In the context of the $T\overline{T}$ deformation of an integrable theory, the deformed theory is also integrable and, correspondingly, the $S$-matrix factorizes into two-to-two $S$-matrices. One may thus hope to be able to extract the renormalized Lagrangian from the $S$-matrix. We do this explicitly for the $T\overline{T}$ deformation of a free massive scalar, to second order in the deformation parameter. Once one has the renormalized Lagrangian one can, in principle, compute all other observables, such as correlation functions. We briefly discuss this, as well as the relation between the renormalized Lagrangian, the $T\overline{T}$ flow equation, and the $S$-matrix. We also mention a more general class of integrability-preserving deformations of a free scalar field theory.

This paper deals with a detailed study of horizons during the gravitational collapse of dust and viscous fluids, under the assumptions of spherical symmetry. The formation and time evolution of collapsing shells, spherically symmetric marginally trapped tubes, as well as the event horizon are determined and compared through analytical and numerical techniques. Using different density profiles of matter, we analyze how the nature of these marginally trapped surfaces modify as we change the energy-momentum tensor. These studies reveal that depending on the mass function and the mass profile, it is possible to envisage situations where dynamical horizons, timelike tubes, or isolated horizons arise.

A novel fractal structure for the cosmological horizon, inspired by COVID-19 geometry, which results in a modified area entropy, is applied to cosmology in order to serve dark energy. The constraints based on a complete set of observational data are derived. There is a strong Bayesian evidence in favor of such a dark energy in comparison to a standard $\mathrm{\Lambda }\mathrm{CDM}$ model and that this energy cannot be reduced to a cosmological constant. Besides, there is a shift toward smaller values of baryon density parameter and toward larger values of the Hubble parameter, which reduces the Hubble tension.

We study the collision of two massive particles with nonzero intrinsic spin moving in the equatorial plane in the background of a Schwarzschild black hole surrounded by quintessential matter field (SBHQ). For the quintessential matter equation of state (EOS) parameter, we assume three different values. It is shown that for collisions outside the event horizon, but very close to it, the centre-of-mass energy ($E_{\mathrm{CM}}$) can grow without bound if exactly one of the colliding particles is what we call near-critical, i.e., if its constants of motion are fine tuned such that the time component of its four-momentum becomes very small at the horizon. In all other cases, $E_{\mathrm{CM}}$ only diverges behind the horizon if we respect the Møller limit on the spin of the particles. We also discuss radial turning points and constraints resulting from the requirement of subluminal motion of the spinning particles.

We study strong gravitational lensing in a static, spherically symmetric, naked singularity spacetime, without a photon sphere. The nature of the singularity is found to be lightlike. We discuss the characteristic lensing features of this naked singularity in the strong deflection limit. In spite of the absence of a photon sphere in this spacetime, the bending angle of light diverges as it approaches the singularity. However, unlike black holes, it is found that the nature of this divergence is nonlogarithmic, and we derive an analytic formula for the same. Moreover, the relativistic rings produced due to strong lensing by the singularity are found to be well separated from each other, making them easy to resolve and possibly detect. These features are expected to be important in the study of strong lensing by ultracompact objects, especially ones without event horizons.

In this work we revisit the topological mass generation of 2-forms and establish a connection to the unique derivative coupling arising in the quartic Lagrangian of the systematic construction of massive 2-form interactions, relating in this way BF theories to Galileon-like theories of 2-forms. In terms of a massless 1-form $A$ and a massless 2-form $B$, the topological term manifests itself as the interaction $B\wedge F$, where $F=\mathrm{d}A$ is the field strength of the 1-form. Such an interaction leads to a mechanism of generation of mass, usually referred to as “topological generation of mass” in which the single degree of freedom propagated by the 2-form is absorbed by the 1-form, generating a massive mode for the 1-form. Using the systematical construction in terms of the Levi-Civita tensor, it was shown that, apart from the quadratic and quartic Lagrangians, Galileon-like derivative self-interactions for the massive 2-form do not exist. A unique quartic Lagrangian ${\epsilon }^{\mu \nu \rho \sigma }{{\epsilon }^{\alpha \beta \gamma }}_{\sigma }{\partial }_{\mu }{B}_{\alpha \rho }{\partial }_{\nu }{B}_{\beta \gamma }$ arises in this construction in a way that it corresponds to a total derivative on its own but ceases to be so once an overall general function is introduced. We show that it exactly corresponds to the same interaction of topological mass generation. Based on the decoupling limit analysis of the interactions, we make supporting arguments for the uniqueness of such a topological mass term and absence of the Galileon-like interactions. Finally, we discuss some preliminary applications in cosmology.

A new truncation scheme based on the cumulant expansion of the one-particle phase-space distribution function for dark matter particles is developed. Extending the method of moments in relativistic kinetic theory, we derive evolution equations which supplement the covariant conservation of the energy-momentum tensor and particle number current. Truncating the cumulant expansion we obtain a closed, covariant and hyperbolic system of equations which can be used to model the evolution of a general relativistic nonideal fluid. As a working example we consider a Friedmann-Lemaître-Robertson-Walker cosmology with dynamic pressure and solve for the time evolution of the effective equation of state parameter.