We develop a number of sum rules comparing spectral integrals involving judiciously chosen weights to integrals over the corresponding Euclidean two-point function. The applications we have in mind are to the hadronic vacuum polarization that determines the most important hadronic correction $a_{\mu }^{\mathrm{HVP}}$ to the muon anomalous magnetic moment. First, we point out how spectral weights may be chosen that emphasize narrow regions in $\sqrt{s}$, providing a tool to investigate emerging discrepancies between data-driven and lattice determinations of $a_{\mu }^{\mathrm{HVP}}$. Alternatively, for a narrow region around the $\rho$ mass, they may allow for a comparison of the dispersive determination of $a_{\mu }^{\mathrm{HVP}}$ with lattice determinations zooming in on the region of the well-known BABAR-KLOE discrepancy. Second, we show how such sum rules can in principle be used for carrying out precision comparisons of hadronic-$\tau$-decay-based data and $e^{+}{e}^{-}\to \text{hadrons}(\gamma )$-based data, where lattice computations can provide the necessary isospin-breaking corrections.

We investigate static quark-antiquark operators based on trial states formed from eigenvectors of the covariant three-dimensional lattice Laplace operator. We test the method by computing the static quark-antiquark potential and comparing results to standard Wilson loop measurements. The new method is efficient not only for on-axis, but also for many off-axis quark-antiquark separations when a fine spatial resolution is required. We further improve the ground-state overlap by using multiple eigenvector pairs, weighted with Gaussian profile functions of the eigenvalues, providing a variational basis. The method presented here can be applied to potential functions for all possible excitations of a gluonic string with fixed ends, hybrid or tetraquark potentials, as well as static-light systems and allows visualization of the spatial distribution of the Laplace trial states.

We study the threshold effect for neutral and charged Drell-Yan productions, associated production of Higgs boson with a massive vector boson and Higgs production in bottom quark annihilation at the Large Hadron Collider to the third order in QCD. Using the third order soft-virtual results for these processes and exploiting the universality of the threshold logarithms, we extract the process-dependent coefficients for these processes and resum large threshold logarithms to next-to-next-to-next-to leading logarithmic (${\mathrm{N}}^3\mathrm{LL}$) accuracy. By matching our results to the recently available ${\mathrm{N}}^3\mathrm{LO}$ results, we provide the most precise theoretical predictions for these processes. We present numerical results for invariant mass distribution and total production cross sections. We find the conventional scale uncertainties of about 0.4% at ${\mathrm{N}}^3\mathrm{LO}$ level in the fixed order results get reduced to as small as less than 0.1% at ${\mathrm{N}}^3\mathrm{LO}+{\mathrm{N}}^3\mathrm{LL}$ level in the high invariant mass region.

In this paper, we analyze the exclusive photoproduction of heavy quarkonia pairs in the collinear factorization framework. We evaluate the amplitude of the process for the $J/\psi -{\eta }_c$ quarkonia pair in the leading order of the strong coupling ${\alpha }_s$, and express it in terms of generalized parton distributions (GPDs) of gluons in the proton. We make numerical estimates in the kinematics of the Electron Ion Collider and find that, in the photoproduction regime, when the virtuality of the photon is much smaller than the quarkonia mass, the cross section of the process is sufficiently large for experimental studies. We demonstrate that the study of this channel can complement existing studies of gluon GPDs from other channels.

In this work, we treat ${\mathrm{\Lambda }}_c(2910{)}^{+}$ and ${\mathrm{\Lambda }}_c(2940{)}^{+}$ as the conventional $udc$ cores dressed with the $D^{*}N$ channel. We provide a possible interpretation to both ${\mathrm{\Lambda }}_c(2910{)}^{+}$ and ${\mathrm{\Lambda }}_c(2940{)}^{+}$ within the same framework. In the study, we consider not only the effects between the conventional triquark core and the $D^{*}N$ channel but also the $D^{*}N\text{−}{D}^{*}N$ interactions. The mass of the ${\mathrm{\Lambda }}_c$ state with $J^P=1/2^{-}$ is larger than that with $J^P=3/2^{-}$ in this unquenched picture, which is very different from the prediction of the conventional quenched quark model. Based on the mass spectrum, the spin parity of ${\mathrm{\Lambda }}_c(2940{)}^{+}$ is more likely to be $1/2^{-}$, while ${\mathrm{\Lambda }}_c(2910{)}^{+}$ prefers $3/2^{-}$. We look forward to the future experiments that can test our results with more precise experimental data.

Inspired by the BESIII Collaboration’s recent amplitude analysis on $D_s^{+}\to {\pi }^{+}{\pi }^0{\pi }^0$, we develop a model based on the chiral unitary approach to describe the $D_s^{+}\to {\pi }^{+}{\pi }^0{\pi }^0$ decay, where $D_s^{+}$ decays into ${\pi }^{+}$ and a quark-antiquark pair through weak decay of a charm quark. The interaction of pseudoscalar mesons produced by the hadronization of a quark-antiquark pair will lead to dynamically generated $f_0(980)$. The dominant amplitudes from resonances $f_0(1370)$ and $f_2(1270)$ in the BESIII fit are also included in our model. In addition to the above contributions, to obtain a good fit, we also add an amplitude from the resonance $f_2(1430)$ to our model. Our model provides a good fit for the $M_{{\pi }^0{\pi }^0}$ and $M_{{\pi }^{+}{\pi }^0}$ invariant mass distributions simultaneously.

A first nonperturbative and unitary treatment of multichannel systems with anomalous thresholds based on realistic potentials is presented. We consider the isospin one-half example system, with $D\pi$, $D\eta$, $D_s\overline{K}$, $D^{*}\pi$, $D^{*}\eta$, $D^{*}\overline{K}$ coupled channels in the $J^P=1^{-}$ partial wave, chosen such that various phenomena that come with the opening of an anomalous threshold can be illustrated in a stepwise procedure by a suitable variation of up, down and strange quark masses. We use a set of low-energy constants in the chiral Lagrangian that were adjusted to a large set of lattice QCD results. The six phase shifts and inelasticity parameters are presented for various choices of the pion mass. For a pion mass of 150 MeV there are no anomalous thresholds encountered. The small change from 150 MeV to 145 MeV pion mass causes a dramatic impact of the anomalous threshold on the phase shifts showing that our results are highly relevant for the extrapolation of lattice QCD calculations toward the physical pion mass.

We explore the exactly duality invariant higher-derivative extension of double field theory due to Hohm, Siegel, and Zwiebach specialized to cosmological backgrounds. Despite featuring a finite number of derivatives in its original formulation, this theory encodes infinitely many ${\alpha }^{\prime }$ corrections for metric, $B$-field, and dilaton, which are obtained upon integrating out certain extra fields. We perform a cosmological reduction with fields depending only on time and show consistency of this truncation. We compute the ${\alpha }^{\prime 4}$ coefficients of the general cosmological classification. As a possible model for how to deal with all ${\alpha }^{\prime }$ corrections in string theory we give a two-derivative reformulation in which the extra fields are kept. The corresponding Friedmann equations are then ordinary second-order differential equations that capture all ${\alpha }^{\prime }$ corrections. We explore the tensionless limit ${\alpha }^{\prime }\to \infty$, which features string frame de Sitter vacua, and we set up the perturbation theory in $\frac{1}{{\alpha }^{\prime }}$.

In this paper, we discuss the gauge reduction with respect to the simplicity$$ constraint in both classical and quantum theory of all dimensional loop quantum gravity. With the gauge reduction with respect to the edge-simplicity constraint being processed and the anomalous vertex simplicity constraint being imposed weakly in holonomy-flux phase space, the simplicity reduced holonomy can be established. However, we find that the simplicity reduced holonomy cannot capture the degrees of freedom of intrinsic curvature, which leads to its failure to construct a correct scalar constraint operator in all dimensional loop quantum gravity (LQG) following the standard strategy. To tackle this problem, we establish a new type of holonomy corresponding to the simplicity reduced connection, which captures the degrees of freedom of both intrinsic and extrinsic curvature properly. Based on this new type of holonomy, we propose three new strategies to construct the scalar constraint operators, which serve as valuable candidates to study the dynamics of all dimensional LQG in the future.

We discuss the propagation of fermions on generic, curved branes in Ishibashi-Kawai-Kitazawa-Tsuchiya-type matrix models. The Dirac operator can be understood either in terms of a Weitzenböck connection, or in terms of the Levi-Civita connection with an extra torsion term. We discuss in detail the coupling of spin to the background geometry using the Jeffreys-Wentzel-Kramers-Brillouin approximation. Despite the absence of local Lorentz invariance in the underlying Ishibashi-Kawai-Kitazawa-Tsuchiya framework, our results agree with the expectations of Einstein-Cartan theory, and differ from general relativity only by an extra coupling to the totally antisymmetric part of the torsion. The case of Friedmann–-Lemaître-–Robertson-–Walker cosmic background solutions is discussed as a special case.

We construct boson star configurations in quantum field theory using the semiclassical gravity approximation. Restricting our attention to the static case, we show that the semiclassical Einstein-Klein-Gordon system for a single real quantum scalar field whose state describes the excitation of $N$ identical particles, each one corresponding to a given energy level, can be reduced to the Einstein-Klein-Gordon system for $N$ complex classical scalar fields. Particular consideration is given to the spherically symmetric static scenario, where energy levels are labeled by quantum numbers $n$, $\ell$, and $m$. When all particles are accommodated in the ground state $n=\ell =m=0$, one recovers the standard static boson star solutions, that can be excited if $n\ne 0$. On the other hand, for the case where all particles have fixed radial and total angular momentum numbers $n$ and $\ell$, with $\ell \ne 0$, but are homogeneously distributed with respect to their magnetic number $m$, one obtains the $\ell$-boson stars, whereas when $\ell =m=0$ and $n$ takes multiple values, the multistate boson star solutions are obtained. Further generalizations of these configurations are presented, including the multi-$\ell$ multistate boson stars, that constitute the most general solutions to the $N$-particle, static, spherically symmetric, semiclassical real Einstein-Klein-Gordon system, in which the total number of particles is definite. In spite of the fact that the same spacetime configurations also appear in multifield classical theories, in semiclassical gravity, they arise naturally as the quantum fluctuations associated with the state of a single field describing a many-body system. Our results could have potential impact on direct detection experiments in the context of ultralight scalar field/fuzzy dark matter candidates.

We present Hamilton’s equations for the teleparallel equivalent of general relativity (TEGR), which is a reformulation of general relativity based on a curvatureless, metric compatible, and torsionful connection. For this, we consider the Hamiltonian for TEGR obtained through the vector, antisymmetric, symmetric and trace-free, and trace irreducible decomposition of the phase space variables. We present the Hamiltonian for TEGR in the covariant formalism for the first time in the literature, by considering a spin connection depending on Lorentz matrices. We introduce the mathematical formalism necessary to compute Hamilton’s equations in both Weitzenböck gauge and covariant formulation, where for the latter we must introduce new fields: Lorentz matrices and their associated momenta. We also derive explicit relations between the conjugate momenta of the tetrad and the conjugate momenta for the metric that are traditionally defined in GR, which are important to compare both formalisms.

Long-lived configurations of massive scalar fields around black holes may form if the coupling between the mass of the scalar field and the mass of the black hole is very small. In this work we analyze the effect of self-interaction in the distribution of the long-lived cloud surrounding a static black hole. We consider both attractive and repulsive self-interactions. By solving numerically the Klein-Gordon equation on a fixed background in the frequency domain, we find that the spatial distribution of quasistationary states may be larger as compared to the noninteracting case. We performed a time evolution to determine the effect of the self-interaction on the lifetime of the configurations our findings indicate that the contribution of the self-interaction is subdominant.

We systematically extend the statement that the configurational entropy provides an alternative approach to studying gravitational stability of compact objects, carried out in the previous work of Gleiser and Jiang [Phys. Rev. D 92, 044046 (2015)]. Inspired by that paper, we try to answer the crucial question; Is there any one-to-one correspondence between the minimum of the configurational entropy and the stability point for each realistic equation of state? In view of the above question, we focus on neutron stars, quark stars, as well as on the third family of compact stars (hybrid stars), where a possible phase transition may lead to the existence of twin stars (stars with equal mass but different radius). In each case, we use a large set of equations of state investigating the possibility to find correlations between the stability region obtained from the traditional perturbation methods to the one obtained by the minimum of configurational entropy. We found that the suggested prediction of the stability by the minimization of the configurational entropy, concerning neutron stars and quark stars, does not have, at least quantitatively, universal validity. However, in several cases it qualitatively predicts the existence of the stability point. In conclusion, the configurational entropy, can be considered as an additional tool which enters into the quiver for studying the stability of compact objects such as for example neutron and quark stars, but taking into account that the accuracy of the predictions depends on the specific character of each equation of state.

We study numerically the scalar wave emission by a nonspherical oscillation of neutron stars in a scalar-tensor theory of gravity with kinetic screening, considering both the monopole and quadrupole mode emission. In agreement with previous results in the literature, we find that the monopole is always suppressed by the screening effect, regardless of the size of the screening radius, $r_{\mathrm{sc}}$. For the quadrupole mode, however, our analysis shows that the suppression only occurs for a screening radius larger than the wavelength of scalar waves, ${\lambda }_{\mathrm{wave}}$, but not for $r_{\mathrm{sc}}<{\lambda }_{\mathrm{wave}}$. This demonstrates that to fully understand the nature of this theory, it is necessary to study other more complex systems, such as neutron star binaries, considering a wide range of $r_{\mathrm{sc}}$ values.

We study a regular rotating black hole evaporating under the Hawking emission of a single scalar field. The black hole is described by the Kerr-black-bounce metric with a nearly extremal regularizing parameter $\ell =0.99r_{+}$. We compare the results with a Kerr black hole evaporating under the same conditions. First, we compute the graybody factors and show that the Kerr-black-bounce evolves toward a non-Schwarzschild-like asymptotic state with $a_{*}\sim 0.47$, differently from a Kerr black hole whose asymptotic spin would be $a_{*}\sim 0.555$. We show that this result depends on the combined contributions of the changes in the graybody factors and in the surface gravity introduced by the regularizing parameter. We also discuss how the surface gravity affects the temperature and the primary emissivity and decreases those quantities with respect to the Kerr black hole. Consequently, the regular black hole has a longer lifetime. Finally, we briefly comment on the possibility of investigating the beyond-the-horizon structure of a black hole by exploiting its Hawking emission.

The spherical photon orbits around a black hole with constant radii are particularly important in astrophysical observations of the black hole. In this paper, the equatorial and nonequatorial spherical photon orbits around Kerr-Newman black holes are studied. The radii of these orbits satisfy a sextic polynomial equation with three parameters: the rotation parameter $u$, charge parameter $w$, and effective inclination angle $v$. For orbits in the polar plane ($v=1$), we find that there are two positive solutions to the orbit equation, one is inside and the other is outside the event horizon. Particularly, we obtain the analytical expressions for the radii of these two orbits that are functions of $u$ and $w$. For orbits in the equatorial plane ($v=0$) around an extremal Kerr-Newman black hole ($u+w=1$), we find three positive solutions to the equation and provide analytical formulas for the radii of the three orbits. We also find that a critical value of rotation parameter $u=\frac{1}{4}$ exists, above which only one retrograde orbit exists outside the event horizon and below which two orbits (one prograde and one retrograde) exist outside the event horizon. For orbits in the equatorial plane around a nonextremal Kerr-Newman black hole, there are four or two positive solutions to the corresponding sextic equation, which we show numerically. The number of solutions depends on the choice of parameters in different regions of the $(u,w)$ plane. A critical curve in the $(u,w)$ plane that separates these regions is also obtained. On this critical curve, the explicit formulas of three solutions are found. There always exist two equatorial photon orbits outside the event horizon in the nonextremal Kerr-Newman case. For orbits between the above two special planes, there are four or two solutions to the general sextic equation. When the black hole is extremal, we find that there is a critical inclination angle $v_{cr}$, below which only one orbit exists and above which two orbits exist outside the event horizon for a rapidly rotating black hole $u>\frac{1}{4}$. At this critical inclination angle, an exact formula for the radii is also derived. Finally, a critical surface in parameter space of ($u$, $w$, $v$) is shown that separates regions with four or two solutions in the nonextremal black hole case.

We investigate relativistic star solutions in mass-varying massive gravity (MVMG) with a diagonal metric. Contrary to the intuition that there is no fundamental difference between diagonal metric and nondiagonal metric solutions regarding relativistic stars, we find that with a diagonal metric, well-behaved relativistic star solutions may not exist except for trivial ones in which the graviton mass is a constant, whereas nontrivial relativistic star solutions have been found in MVMG with a nondiagonal metric. The reason is that with a diagonal metric, the field equations constitute a system of differential algebraic equations of differential index-2 with two extra constraints that have a significant influence on the system, rendering the relativistic star solution with a nontrivial graviton mass configuration impossible in most cases.

Black bounces are spacetimes that can describe, depending on certain parameters, black holes or wormholes. In this work, we use a method to obtain the matter content that generates black bounce solutions in general relativity. The method is constructed in a general way, and as models, we apply it to the Simpson-Visser black bounce solution and the Bardeen-type black bounce solution. We obtain that these metrics are solutions of Einstein’s equations when we consider the coupling of the gravitational interaction with a phantom scalar field with a nonlinear electrodynamics. The presence of the phantom scalar field is linked to the fact that this type of solution violates the null energy condition. We analyze separately the energy conditions associated with the stress-energy tensor for the scalar field and for the electromagnetic field.