In this work, we make a study of the $T_{cc}^{+}$ state observed by the LHCb collaboration in 2021. In obtaining the effective potentials using the one-boson-exchange potential model we use an exponential form factor and find that, in the short and medium range, the contributions of the $\pi$, $\rho$, and $\omega$ exchanges are comparable while in the long range the pion-exchange contribution is dominant. Based on the assumption that $T_{cc}^{+}$ is a loosely bound state of $D^{*}D$, we focus on its three-body decay using the meson-exchange method. Considering that the difference between the thresholds of $D^{*+}{D}^0$ and $D^{*0}{D}^{+}$ is even larger than the binding energy of $T_{cc}^{+}$, the isospin-breaking effect is amplified by the small binding energy of $T_{cc}^{+}$. Explicitly including such an isospin-breaking effect we obtain, by solving the Schrödinger equation, that the probability of the isoscalar component is about 91% while that of the isovector component is around 9% for $T_{cc}^{+}$. Using the experimental value of the mass of $T_{cc}^{+}$ as an input, we obtain the wave function of $T_{cc}^{+}$ and further obtain its width via the three-body hadronic as well as the radiative decays. The total width we obtain is in agreement with the experimental value of the LHCb measurement with a unitarized Breit-Wigner profile. Conversely, the current results support the conclusion that $T_{cc}^{+}$ is a hadronic molecule of $D^{*}D$.

Using a diffusion Monte Carlo algorithm, we calculated the spectra of all possible $S$-wave fully heavy pentaquarks within the framework of the quark model. Our aim was to compare the masses of different spin-color configurations corresponding to the same spatial wave function for each quark composition. In particular, we computed the masses of the configuration with the maximum number of undistinguishable quarks and those of all the possible $\mathrm{baryon}+\mathrm{meson}$ splittings compatible with the total number of $b$’s and $c$’s for a given pentaquark. What we found was that, in all cases, compact $\mathrm{baryon}+\mathrm{meson}$ configurations had lower masses than their more symmetric counterparts. Moreover, those “molecular” associations were unstable (with larger masses) that their infinitely separated noninteracting pieces except in the case of $(ccb)(c\overline{b})$ and $(bbc)(b\overline{c})$ pentaquarks. In any case, even for unstable arrangements, the excess masses are so small ($\sim 20–60\mathrm{MeV}$) as to make those compact molecular structures serious candidates to be experimentally detected.

Using $2.93{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ collision data collected with the BESIII detector at the center-of-mass energy of 3.773 GeV, we investigate the semileptonic decays $D^{+}\to {\pi }^{+}{\pi }^{-}{\ell }^{+}{\nu }_{\ell }$ ($\ell =e$ and $\mu$). The $D^{+}\to f_0(500){\mu }^{+}{\nu }_{\mu }$ decay is observed for the first time. By analyzing simultaneously the differential decay rates of $D^{+}\to f_0(500){\mu }^{+}{\nu }_{\mu }$ and $D^{+}\to f_0(500)e^{+}{\nu }_e$ in different ${\ell }^{+}{\nu }_{\ell }$ four-momentum transfer intervals, the product of the relevant hadronic form factor $f_{+}^{f_0}(0)$ and the magnitude of the $c\to d$ Cabibbo-Kobayashi-Maskawa matrix element $|V_{cd}|$ is determined to be $f_{+}^{f_0}(0)|V_{cd}|=0.143\pm 0.014_{\mathrm{stat}}\pm 0.011_{\mathrm{syst}}$ for the first time. With the input of $|V_{cd}|$ from the global fit in the standard model, we determine $f_{+}^{f_0}(0)=0.63\pm 0.06_{\mathrm{stat}}\pm 0.05_{\mathrm{syst}}$. The absolute branching fractions of $D^{+}\to f_0(500{)}_{({\pi }^{+}{\pi }^{-})}{\mu }^{+}{\nu }_{\mu }$ and $D^{+}\to {\rho }_{({\pi }^{+}{\pi }^{-})}^0{\mu }^{+}{\nu }_{\mu }$ are determined as $(0.72\pm 0.13_{\mathrm{stat}}\pm 0.08_{\mathrm{syst}})\times {10}^{-3}$ and $(1.64\pm 0.13_{\mathrm{stat}}\pm 0.10_{\mathrm{syst}})\times {10}^{-3}$. Combining these results with those of previous BESIII measurements on their semielectronic counterparts from the same data sample, we test lepton flavor universality by measuring the branching fraction ratios ${\mathcal{B}}_{D^{+}\to {\rho }^0{\mu }^{+}{\nu }_{\mu }}/{\mathcal{B}}_{D^{+}\to {\rho }^0{e}^{+}{\nu }_e}=0.88\pm 0.10$ and ${\mathcal{B}}_{D^{+}\to f_0(500){\mu }^{+}{\nu }_{\mu }}/{\mathcal{B}}_{D^{+}\to f_0(500)e^{+}{\nu }_e}=1.14\pm 0.26$, which are compatible with the standard model expectation.

It is well known that locally defined marginally outer trapped surface (MOTS) is null and coincident with the event horizon of an unperturbed static Schwarzschild black hole. This is however not true for an accreting black hole for which MOTS separates out and turns spacelike. In this Letter, we obtain the necessary and sufficient condition for MOTS to remain null and coincident with the event horizon even when matter is continuously accreting on. This also has an important bearing on the quantum Hawking radiation which is supposed to emanate from the MOTS, and it cannot propagate out to infinity unless MOTS is null. The condition is that infalling timelike type I fluid should turn null or type II as it falls on the horizon. This transition from timelike to null is caused by the tidal deformation of the infalling fluid, and that produces an outward directed heat flux giving rise to Vaidya radiation emanating out of the boundary of accreting zone. We thus predict a remarkable new phenomena that accreting black hole radiates classical Vaidya radiation that paves the way for the Hawking radiation.

We compute new exact analytic expressions for one-loop scalar effective actions in Kerr (A)dS black hole (BH) backgrounds in four and five dimensions. These are computed by the connection coefficients of the Heun equation via a generalization of the Gelfand-Yaglom formalism to second-order linear ordinary differential equations with regular singularities. The expressions we find are in terms of Nekrasov-Shatashvili special functions, making explicit the analytic properties of the one-loop effective actions with respect to the gravitational parameters and the precise contributions of the quasinormal modes. The latter arise via an associated integrable system. In particular, we prove asymptotic formulas for large angular momenta in terms of hypergeometric functions and give a precise mathematical meaning to Rindler-like region contributions. Moreover, we identify the leading terms in the large distance expansion as the point particle approximation of the BH and their finite size corrections as encoding the BH tidal response. We also discuss the exact properties of the thermal version of the BH effective actions by providing a proof of the Denef-Hartnoll-Sachdev formula and explicitly computing it for new relevant cases. Although we focus on the real scalar field in dS-Kerr and (A)dS-Schwarzschild in four and five dimensions, similar formulas can be given for higher spin matter and radiation fields in more general gravitational backgrounds.

Various diagnostics of the emergence of an arrow of time in the bulk description of a holographic theory have been proposed, including the decay of some real time correlation functions and the appearance of type ${\mathrm{III}}_1$ von Neumann algebras carrying half-sided modular inclusions. This Letter puts forward a close parallel between these diagnostics and a quantum formulation of the ergodic hierarchy of dynamical systems. Theories with an emergent spacetime appear to sit near the top of this hierarchy.

We discuss peculiarities of the Schwinger-DeWitt technique for quantum effective action, associated with the origin of dimensionally regularized double-pole divergences of the one-loop functional determinant for massive Proca model in a curved spacetime. These divergences have the form of the total-derivative term generated by integration by parts in the functional trace of the heat kernel for the Proca vector field operator. Because of the nonminimal structure of second-order derivatives in this operator, its vector field heat kernel has a nontrivial form, involving the convolution of the scalar d’Alembertian Green’s function with its heat kernel. Moreover, its asymptotic expansion is very different from the universal predictions of Gilkey-Seeley heat kernel theory because the Proca operator violates one of the basic assumptions of this theory—the nondegeneracy of the principal symbol of an elliptic operator. This modification of the asymptotic expansion explains the origin of double-pole total-derivative terms. Another hypostasis of such terms is in the problem of multiplicative determinant anomalies—lack of factorization of the functional determinant of a product of differential operators into the product of their individual determinants. We demonstrate that this anomaly should have the form of total-derivative terms and check this statement by calculating divergent parts of functional determinants for products of minimal and nonminimal second-order differential operators in curved spacetime.

Supergeometric quantum field theories (SG-QFTs) are theories that go beyond the standard supersymmetric framework, since they allow for general scalar-fermion field transformations on the configuration space of a supermanifold, without requiring an equality between bosonic and fermionic degrees of freedom. After revisiting previous considerations, we extend them by calculating the one-loop effective action of minimal SG-QFTs that feature nonzero fermionic curvature in two and four spacetime dimensions. By employing an intuitive approach to the Schwinger–DeWitt heat-kernel technique and a novel field-space generalized Clifford algebra, we derive the ultraviolet structure of characteristic effective-field-theory (EFT) operators up to four spacetime derivatives that emerge at the one-loop order and are of physical interest. Upon minimizing the impact of potential ambiguities due to the so-called multiplicative anomalies, we find that the EFT interactions resulting from the one-loop supergeometric effective action are manifestly diffeomorphically invariant in configuration space. The extension of our approach to evaluating higher loops of the supergeometric quantum effective action is described. The emerging landscape of theoretical and phenomenological directions for further research of SG-QFTs is discussed.

We investigate gravitational waves generated in $f(Q,B)$ nonmetric gravity, i.e., a theory of gravity described by a nonmetric compatible connection, free of torsion and curvature. It is an extension of symmetric teleparallel gravity, equipped with a boundary term $B$. This theory exhibits gravitational waves regardless of the gauge adopted: they are the standard massless tensors plus a massive scalar gravitational wave like in the case of $f(R)$ gravity. It is precisely the boundary term $B$ that generates the massive scalar mode with an effective mass $m_B$ associated to a Klein-Gordon equation in the linearized boundary term. As in $f(Q)$ gravity also in $f(Q,B)$ nonmetric gravity, a free test particle follows a geodesic motion due to the covariant conservation with respect to the Levi-Civita connection of the energy and momentum densities on-shell. Therefore, in $f(Q,B)$ gravity, the proper acceleration between two neighboring worldlines traveled by two free pointlike particles is governed by a first-order geodesic deviation equation in the metric perturbation $h_{\mu \nu }$. Thanks to this approximate linear equation, $f(Q,B)$ nonmetric gravity shows three polarization modes: two massless transverse tensor radiation modes, with helicity equal to 2, reproducing the standard plus and cross modes, exactly as in general relativity, and an additional massive scalar wave mode with transverse polarization of zero helicity. We obtain the same result both by considering the coincident gauge and by leaving the gauge free. This happens because, at first order, the boundary term $B$ remains unchanged as well as the linearized field equations of metric tensor and connection in vacuum. Furthermore, we derive the energy and momentum balance equations and the equations of motion of the deviation, both in a generic theory of gravitation, where the matter stress-energy tensor ${T^{\alpha }}_{\beta }$ is Levi-Civita covariantly not conserved, i.e., ${\mathcal{D}}_{\alpha }{T^{\alpha }}_{\beta }\ne 0$. In summary, three degrees of freedom propagate in the $f(Q,B)$ linearized theory with amplitudes ${\tilde{h}}^{(+)}$ and ${\tilde{h}}^{(\times )}$ for tensor modes and amplitude ${\tilde{h}}^{(s)}$ for the scalar mode. Specifically, both $f(Q,B)$ and $f(R)$ gravity involve the same massive transverse scalar perturbation.

At the supranuclear densities achieved inside a neutron star, matter may exhibit extreme properties. In particular, it may be the case that a suitable average of the speed of sound squared exceeds the so-called conformal limit, i.e., $⟨c_s^2⟩>1/3$, a condition that is equivalent to the positiveness of the trace of the energy-momentum tensor at the stellar center. This property, which holds for highly compact neutron stars obeying many (but not any) realistic equations of state, would turn these objects into interesting laboratories for tests of several scalar extensions of general relativity. In this paper, we investigate how rapid rotation influences the superconformality of the averaged speed of sound squared and modified gravity effects that depend thereupon, paying particular attention to scalar-tensor theories prone to the spontaneous scalarization effect.

The upcoming discoveries of pulsars orbiting the center of the Milky Way will present unparalleled opportunities to examine the causal structure of the spacetime geometry of Sagittarius A*. In this paper, we investigate the fully relativistic propagation time delay of pulsar signals in the Joshi-Malafarina-Narayan (JMN-1) and Janis-Newman-Winicour (JNW) spacetimes. This delay arises from the spacetime curvatures in the vicinity of these ultracompact objects, induced by the intense gravitational field near the Galactic Center (GC). Using the principles of gravitational lensing, we compute the arrival time of photons originating from a pulsar in orbit around the GC. To validate our approach, we compare our time delay analysis of the Schwarzschild black hole with the corresponding delay in the post-Newtonian framework. Subsequently, we find that the propagation time of pulsar signal is greater and lesser for the given horizonless ultracompact objects for direct and indirect propagation, respectively. Therefore, our results suggest quite significant propagation time delay differences in JMN-1 and JNW spacetimes, when compared to the Schwarzschild black hole case. This can be inferred as a possible distinguishing feature for these ultracompact objects’ geometries.

For interacting classical field theories, such as general relativity, exact solutions typically can only be found by imposing physically motivated (Killing) symmetry assumptions. Such highly symmetric solutions are then often used as backgrounds in a perturbative approach to more general nonsymmetric solutions. If the theory is in addition a gauge theory such as general relativity, the issue arises how to consistently combine the perturbative expansion with the gauge reduction. For instance, it is not granted that the corresponding constraints expanded to a given order still close under Poisson brackets with respect to the nonsymmetric degrees of freedom up to higher order. If one is interested in the problem of backreaction between symmetric and nonsymmetric degrees of freedom, then one also must consider the symmetric degrees of freedom as dynamical variables which supply additional terms in Poisson brackets with respect to the symmetric degrees of freedom and the just mentioned consistency problem becomes even more complicated. In this paper, we show for a general theory how to consistently combine all of these notions. The idea is to first perform the exact gauge reduction on the full phase space, which results in the reduced phase space of observables and physical Hamiltonian, respectively, and secondly, expand that physical Hamiltonian perturbatively. Surprisingly, this strategy is not only practically feasible but also avoids the above mentioned tensions. There is also a variant of this strategy that employs only a partial gauge reduction with respect to some of the nonsymmetric degrees of freedom on the full phase space. We show that in perturbation theory,z the left over constraints close up to higher orders but not exactly, unless there is only one of them such as in cosmology. Since such classically anomalous constraints are problematic to quantize, the full gauge reduction for which these issues are absent is preferred in this case.

Accurate waveform modeling is crucial for parameter estimation in gravitational wave astronomy, impacting our understanding of source properties and the testing of general relativity. The precession of orbital and spin angular momenta in binary black hole (BBH) systems with misaligned spins presents a complex challenge for gravitational waveform modeling. Current precessing BBH waveform models employ a coprecessing frame, which precesses along with the binary. In this paper, we investigate a source of bias stemming from the mismodeling of ringdown frequency in the coprecessing frame. We find that this mismodeling of the coprecessing frame ringdown frequency introduces systematic biases in parameter estimation, for high-mass systems in particular, and in the inspiral-merger-ringdown (IMR)-consistency test of general relativity. Employing the waveform model imrphenomxphm, we conduct an IMR-consistency test using a Fisher matrix analysis across parameter space, as well as full injected signal parameter estimation studies. Our results show that this mismodeling particularly affects BBH systems with high-mass ratios, high-spin magnitudes, and highly inclined spins. These findings suggest inconsistencies for all waveform models which do not address this issue.

We construct a four-dimensional spacetime using a three-dimensional contact manifold equipped with a degenerate metric. The degenerate metric is set to be compatible with the contact structure. The compatibility condition is defined in this paper. Our construction yields a Ricci tensor of a particularly simple form, which leads to a solution of the Einstein equation with a null dust and cosmic strings. The solution includes two arbitrary functions: the energy density of the null dust and the number density of the cosmic strings. When there exist the cosmic strings, the spacetime is of Petrov type D. Otherwise, the spacetime is conformally flat. For some simple matter densities, we examine the Einstein equation in detail.

Einstein-Cartan gravity is a close historical sibling of general relativity that allows for spacetime torsion. As a result, angular momentum couples to spacetime geometry in a similar way to energy. While consequences of this are well studied on cosmological scales, their role in neutron star physics is largely underexplored. We study the effects that torsion, sourced by either microphysical spin or macroscopic angular momentum, has on neutron stars. For this, we use a simplified polytropic model to quantify the microphysical coupling to torsion. We also derive expressions to model rotation-induced torsion effects and estimate the consequences for rotating neutron stars with different rotation rates. We find that the presence of torsion in general leads to neutron stars with smaller radii and masses but higher central densities. Realistic models for microphysical spin lead to torsion effects that have no relevant influence on the neutron star structure. Rotation-induced torsion effects, however, can decrease the radius by up to 900 m, which is comparable to the increase due to centrifugal forces. Depending on which effect dominates, this leads to a torsion-induced spin-up or spin-down of the neutron star. We conclude that torsion effects due to rotation can not be neglected and are large enough to be tested using current or near-future technology.

We study the (anti-)self-duality conditions under which the electric and magnetic parts of the conserved charges of the dyonic Kerr-Newman-NUT-anti-de Sitter solution become equivalent. Within a holographic framework, the stress tensor and the boundary Cotton tensor are computed from the electric/magnetic content of the Weyl tensor. The holographic stress tensor/Cotton tensor duality is recovered along the (anti-)self-dual curve in parameter space. We show that the latter not only implies a duality relation for the mass but also for the angular momentum. The partition function is computed to first order in the saddle-point approximation and a Bogomol’nyi-Prasad-Sommerfield bound is obtained. The ground state of the theory is enlarged to all the (anti-)self-dual configurations when the $SO(4)$ and $U(1)$ Pontryagin densities are introduced. We demonstrate this at the level of the action and variations thereof.

Core-collapse supernovae (CCSNe) are potential multimessenger events detectable by current and future gravitational wave (GW) detectors. The GW signals emitted during these events are expected to provide insights into the explosion mechanism and the internal structures of neutron stars. In recent years, several studies have empirically derived the relationship between the frequencies of the GW signals originating from the oscillations of protoneutron stars (PNSs) and the physical parameters of these stars. This study applies the Hilbert-Huang transform (HHT) [Huang et al., The empirical mode decomposition and the Hilbert spectrum for nonlinear and non-stationary time series analysis, Proc. R. Soc. A 454, 903 (1998)] to extract the frequencies of these modes to infer the physical properties of the PNSs. The results exhibit comparable accuracy to a short-time Fourier transform-based estimation, highlighting the potential of this approach as a complementary method for extracting physical information from GW signals of CCSNe.

We innovate a systematic investigation of the weak cosmic censorship conjecture (WCCC) using gedanken experiments involving black hole perturbations by test particles. We classify various WCCC violation scenarios proposed in recent decades, including Hubeny, mixed, and the latest Sorce-Wald (SW). We provide general formulas in each case, and resolve contradictions in numerous studies. Following the SW type, our analysis reveals that WCCC depends on the sign choice of the parameter $W\equiv (\frac{\partial S}{\partial T}{)}_{Q_i;T=0}$ of the extremal black holes. $W>0$ preserves WCCC and $W<0$ would indicate potential violation. We show explicitly that $W>0$ for spherically symmetric and static black holes, and for general case, we argue that it is protected by the black hole no-hair theorem. We also consider asymptotically (A)dS black holes and argue that there can be no violation either.

The baryon acoustic oscillations (BAO) feature in the two-point correlation function (TPCF) of discrete tracers such as galaxies is an accurate standard ruler. The covariance matrix of the TPCF plays an important role in determining how the precision of this ruler depends on the number density and clustering strength of the tracers, as well as the survey volume. An eigen-decomposition of this matrix provides an objective way to separate the contributions of cosmic variance from those of shot-noise to the statistical uncertainties. For the signal-to-noise levels that are expected in ongoing and next-generation surveys, the cosmic variance eigen-modes dominate. These modes are smooth functions of scale, meaning that they are insensitive to the modest changes in binning that are allowed if one wishes to resolve the BAO feature in the TPCF; they provide a good description of the correlated residuals which result from fitting smooth functional forms to the measured TPCF; they motivate a simple but accurate approximation for the uncertainty on the linear point (LP) estimate of the BAO distance scale. This approximation allows one to quantify the precision of the BAO distance scale estimate without having to generate a large ensemble of mock catalogs and explains why: the uncertainty on the LP does not depend on the functional form fitted to the TPCF or the binning used; the LP is more constraining than the peak or dip scales in the TPCF; the evolved TPCF is less constraining than the initial one, so that reconstruction schemes can yield significant gains in precision.

We study the impact of an early dark energy component (EDE) present during big bang nucleosynthesis (BBN) on the elemental abundances of deuterium D/H, and helium $Y_p$, as well as the effective relativistic degrees of freedom $N_{\mathrm{eff}}$. We consider a simple model of EDE that is constant up to a critical time. After this critical time, the EDE transitions into either a radiation component that interacts with the electromagnetic plasma, a dark radiation component that is uncoupled from the plasma, or kination that is also uncoupled. We use measured values of the abundances and $N_{\mathrm{eff}}$ as determined by cosmic microwave background observations to establish limits on the input parameters of this EDE model. In addition, we explore how those parameters are correlated with BBN inputs; the baryon to photon ratio ${\eta }_b$, neutron lifetime ${\tau }_n$, and number of neutrinos $N_{\nu }$. Finally, we study whether this setup can alleviate the tension introduced by recent measurements of the primordial helium abundance.