We report decay-rate $CP$ asymmetries of the singly-Cabibbo-suppressed decays ${\mathrm{\Xi }}_c^{+}\to {\mathrm{\Sigma }}^{+}{h}^{+}{h}^{-}$ and ${\mathrm{\Lambda }}_c^{+}\to p{h}^{+}{h}^{-}$, with $h=K$, $\pi$, measured using $428{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ collisions collected by the Belle II experiment at the SuperKEKB collider. The results, $A_{CP}({\mathrm{\Xi }}_c^{+}\to {\mathrm{\Sigma }}^{+}{K}^{+}{K}^{-})=(3.7\pm 6.6\pm 0.6)\%$, $A_{CP}({\mathrm{\Xi }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\pi }^{+}{\pi }^{-})=(9.5\pm 6.8\pm 0.5)\%$, $A_{CP}({\mathrm{\Lambda }}_c^{+}\to p{K}^{+}{K}^{-})=(3.9\pm 1.7\pm 0.7)\%$, $A_{CP}({\mathrm{\Lambda }}_c^{+}\to p{\pi }^{+}{\pi }^{-})=(0.3\pm 1.0\pm 0.2)\%$, where the first uncertainties are statistical and the second systematic, agree with $CP$ symmetry. From these results we derive the sums $A_{CP}({\mathrm{\Xi }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\pi }^{+}{\pi }^{-})+A_{CP}({\mathrm{\Lambda }}_c^{+}\to p{K}^{+}{K}^{-})=(13.4\pm 7.0\pm 0.9)\%$, $A_{CP}({\mathrm{\Xi }}_c^{+}\to {\mathrm{\Sigma }}^{+}{K}^{+}{K}^{-})+A_{CP}({\mathrm{\Lambda }}_c^{+}\to p{\pi }^{+}{\pi }^{-})=(4.0\pm 6.6\pm 0.7)\%$, which are consistent with the $U$-spin symmetry prediction of zero. These are the first measurements of $CP$ asymmetries for individual hadronic three-body charmed-baryon decays.

It has been observed that the hint about dynamical dark energy in the Dark Energy Spectroscopic Instrument (DESI) baryon acoustic oscillation (BAO) observation might point to nonminimally coupled gravity. We report the first $3\sigma$ evidence for nonminimal coupling in a model-agnostic effective field theory (EFT) approach. In a nonparametric reconstruction approach, we detect a clear departure from the general relativity expectation of nonminimal coupling based on a combined analysis of DESI data release 2 BAO together with cosmic microwave background and type Ia supernova data. Also, it is found that current data can constrain up to the quadratic order ($n=2$) if the EFT function representing nonminimal coupling is Taylor expanded as a general function of the dark energy fraction ${\mathrm{\Omega }}_{\mathrm{DE}}$, i.e., ${\mathrm{\Omega }}^{\mathrm{EFT}}(a)={\sum }_{i=0}^n{c}_i^{\mathrm{EFT}}{\mathrm{\Omega }}_{\mathrm{DE}}^i(a)$. Our findings constitute a detection of modified-gravity effects and call for a more flexible parametrization of the EFT functions than commonly used ones in literature.

Recent studies on the dark photon (DP) production in collapsing stars argue that the cooling effect induced by DPs can hinder supernova explosions and lead to a “failing supernova” constraint on the photon-DP mixing parameter $\epsilon$. In order to verify the idea, we perform two-dimensional neutrino-radiation hydrodynamic simulations coupled with the DP production with the masses of 0.3 and 0.45 MeV. We find that the shock revival does not happen until the end of the simulations when $\epsilon \gtrsim 3\times {10}^{-9}$. The photon-DP mixing parameter above this value can be excluded by the failing supernova argument. Interestingly, our constraint roughly coincides with the one reported by the previous studies which adopted the postprocessing framework. This result motivates one to investigate a wider parameter range of DPs with self-consistent simulations and evaluate uncertainties in the constraint.

We study the $\gamma \gamma \to {\tau }^{+}{\tau }^{-}$ process including full ${\tau }^{+}{\tau }^{-}$ spin information in Pb-Pb ultraperipheral collisions and at lepton colliders. We present the predictions for the corresponding cross sections and spin correlations at next-to-leading order (NLO) electroweak precision, and find that the NLO electroweak contributions are numerically small for the observables considered. Additionally, we use the spin correlations obtained in this paper to analyze the quantum entanglement in the ${\tau }^{+}{\tau }^{-}$ system of the $\gamma \gamma \to {\tau }^{+}{\tau }^{-}$ process. Our results show that there is a genuine entangled configuration near the ${\tau }^{+}{\tau }^{-}$ invariant mass threshold. This work is helpful for studying the $\tau$-pair production induced by photon-photon collision at high-energy colliders.

A central question in exotic-hadron physics is their internal structure whether these states are loosely bound hadronic molecules or compact multiquark configurations. To shed light on this issue, we develop a model that incorporates mixing between hadronic-molecular and compact multiquark components. We then apply this framework to the specific case of the $T_{cc}(3875{)}^{+}$ and analyze the peak structure in the $D^0{D}^0{\pi }^{+}$ invariant-mass spectrum reported by LHCb. We find that the model admits three solutions of comparable fit quality that can account for the $T_{cc}(3875{)}^{+}$. One solution corresponds to a predominantly compact tetraquark configuration. The other two solutions imply a molecular $T_{cc}(3875{)}^{+}$: (1) the $T_{cc}(3875{)}^{+}$ is a $D^{*+}{D}^0$ molecule and an additional $D^{*0}{D}^{+}$ molecular state appears; (2) the $T_{cc}(3875{)}^{+}$ is a $D^{*0}{D}^{+}$ molecule and an additional $D^{*+}{D}^0$ molecular state is found below the $D^0{D}^0{\pi }^{+}$ threshold. These molecular states are not simple $I=0$ states, but mixtures of $I=0$ and $I=1$ states. We show that all three scenarios are also consistent with the experimentally observed near-threshold $D^0{D}^0$ and $D^0{D}^{+}$ invariant-mass distributions.

We study the information paradox of four-dimensional covariant black holes inspired by loop quantum gravity (LQG) with two well motivated solutions. We first prepare the spacetime in the Hartle-Hawking state, compute the radiation entropy, and recover a linear growth at late time. When considering the mass loss and incorporating graybody factors, we show that for Metric 1 the LQG parameter $\zeta$ leaves temperature and Planckian factor of the spectrum unchanged but enhances the near-horizon barrier, leading to a faster evaporation rate as $M$ decreases. This behavior contrasts sharply with Metric 2, which has slow evaporation rate at small $M$ and admits a nonsingular continuation suggestive of a remnant or a black-to-white-hole transition. We then apply the island prescription on the eternal background and find that quantum extremal surfaces exist in Metric 1 geometries; $\zeta$ gives a larger island and the island suppresses the late-time entropy growth, preserving unitarity. Our results highlight that covariance-respecting LQG black hole do not exhibit a universal late-time behavior.

In this work, we study the long-range interactions in nongravitational field theories and their behavior in the deep infrared. To model such effects, we consider a nonlocal scalar theory obtained by adding a $\varphi {\square }^{-1}\varphi$ term to the local action. Using the functional renormalization group, we analyze its infrared fixed-point structure. Within the local potential approximation (LPA), we show that nonlocality modifies phase-transition patterns and can induce symmetry breaking. Extending the LPA beyond polynomial truncations, we examine the convexity property of the effective potential as $k\to 0$ and find that the flow becomes singular for ${\lambda }^2>0$ before reaching the deep infrared. Including the scale-dependent wave function renormalization, $Z_k$ (${\mathrm{LPA}}^{\prime }$), we find that the infrared-stable fixed point is the nonlocal Gaussian fixed point. We then generalize the model to $\varphi {\square }^{\sigma /2}\varphi$ and analyze how the infrared properties depend on $\sigma$. With appropriate scaling choices, we show that the infrared behavior remains unchanged up to $\sigma =d/2$ and follows Sak’s prediction up to $\sigma =2$. Finally, we study higher-derivative cases within the LPA, focusing on $\sigma =4$, which corresponds to isotropic Lifshitz criticality, and obtain results consistent with earlier work.

We investigate the perturbative structure of the proper time renormalization group flow in scalar and Yang-Mills theories. Although the proper time flow does not belong to the class of exact functional renormalization group equations, we show that it correctly reproduces the universal coefficients of the $\beta$ functions at one and two loops. For the O(N) scalar theory, we derive the one- and two-loop contributions to the running quartic coupling and also confirm the expected anomalous dimension. For the SU(N) Yang-Mills theory, using the background field method, we compute the gauge coupling renormalization recovering the correct two-loop $\beta$ function without generating any gauge-symmetry–violating terms. These results highlight that, despite its limitations for reconstructing the full effective action, the proper time flow retains the essential universal content of renormalization, accounting for its reliability in diverse applications ranging from statistical models to quantum gravity.

Coulomb branch amplitudes of maximally supersymmetric Yang-Mills theory display infrared properties different from their conformal counterparts. While the four-leg amplitude is known to very high perturbative orders, amplitudes of higher multiplicity fall into an uncharted territory starting already from two loops. The reason for this is that they are not easily amenable to traditional techniques like canonical differential equations due to the uncontrolled swelling of solutions to integration-by-parts identities. In this paper, we break the barrier for the five-leg amplitude using a technique based on the analysis of Newton polytopes corresponding to Feynman/Schwinger integrands and their tropical geometry. Specifically, we analytically evaluate the near mass-shell limit of the off-shell pentabox in terms of Goncharov polylogarithms.

In this paper, we study $2+2$ direct product spacetimes sourced by separated electromagnetic and Yang-Mills fields within Weyl conformal gravity. We prove that all such configurations admit at least two independent, commuting non-null Killing vectors, which we use to find general solutions. As a special case, we obtain a generalization of the Birkhoff-Riegert theorem to all spacetimes containing a two-dimensional subspace of constant Gaussian curvature, and we also revisit the original formulation of the theorem. We further analyze the resulting solutions in terms of Weyl equivalence classes. Their connections to known solutions in both Weyl conformal gravity and Einstein gravity are established through conformal relations. We also examine the fundamental physical and geometric properties of the newly obtained configurations and their equivalence classes.

We construct a stationary, vacuum five-dimensional black ring spacetime with rotation only along the $S^2$ direction that is free of conical singularities. We use a solution-generating technique to add external gravitational fields and show these can be used to remove conical singularities from an asymptotically flat black ring with a rotating $S^2$.

With the upcoming third-generation gravitational-wave detectors comes the need to build complete, faithful, and fast waveform models for asymmetric-mass-ratio compact binaries. Most efforts within the self-force community have focused on modeling these binaries’ inspiral regime, but for ground-based detectors the systems’ final merger can represent the dominant part of the signal. Recent work by three of us has extended the multiscale self-force framework through the transition-to-plunge and merger-ringdown regimes for nonspinning binaries. In this paper, we generalize the next-to-next-to-leading-order transition-to-plunge waveform model to include the spin of the primary black hole. We also improve the construction of composite inspiral-transition waveform models by performing a change of variables on the binary’s mechanical phase space during the transition to plunge. We provide detailed discussions of our numerical implementation and comparisons with numerical relativity simulations.

Imaging systematics refers to the inhomogeneous distribution of a galaxy sample caused by varying observing conditions and astrophysical foregrounds. Current mitigation methods correct the galaxy density fluctuations $n_{\mathrm{gal}}/{\overline{n}}_{\mathrm{gal}}$ caused by imaging systematics assuming that all galaxies in a sample have the same $n_{\mathrm{gal}}/{\overline{n}}_{\mathrm{gal}}$. Under this assumption, the corrected sample cannot perfectly recover the true correlation function. We name this effect subsample systematics. For a galaxy sample, even if its overall sample statistics [redshift distribution $n(z)$, galaxy bias $b(z)$], are accurately measured, $n(z)$, $b(z)$ can still vary across the observed footprint. It makes the correlation function amplitude of galaxy clustering higher, while correlation functions for galaxy-galaxy lensing and cosmic shear do not have noticeable change. Such a combination could potentially degenerate with physical signals on small angular scales, such as the amplitude of galaxy clustering, the impact of neutrino mass on the matter power spectrum, etc. subsample systematics cannot be corrected using imaging systematics mitigation approaches that rely on the cross-correlation signal between imaging systematics maps and the observed galaxy density field. In this paper, we derive formulated expressions of subsample systematics, demonstrating its fundamental difference with other imaging systematics. We also provide several toy models to visualize this effect. Finally, we discuss a potential method to estimate and mitigate subsample systematics by forward modeling its behavior using synthetic source injection.

False vacuum decay typically proceeds via the nucleation of spherical bubbles of true vacuum, described by $O(4)$ symmetric field configurations in Euclidean time. In this work, we investigate how the presence of cosmic strings can catalyze the decay process. To this end, we consider a complex scalar field charged under a global or local $U(1)$ symmetry. Assuming a nontrivial vacuum manifold, realizable for example in a simple sextic potential, we derive relativistic bounce solutions with $O(2)\times O(2)$ symmetry, corresponding to elongated bubbles seeded by a cosmic string of the same scalar field. Building up on earlier results in the literature, we identify the region of parameter space where vacuum decay predominantly proceeds via this alternative channel, thereby providing an explicit mechanism for the quantum decay of cosmic strings. Finally, we present an initial discussion of the gravitational wave signal associated with this type of vacuum decay and its possible connection to the recently observed stochastic signal in pulsar timing arrays.

Dark matter (DM) candidates with very small masses, and correspondingly large number densities, have gained significant interest in recent years. These DM candidates are typically said to behave “classically.” More specifically, they are often assumed to reside in an ensemble of coherent states. One notable exception to this scenario is when isocurvature fluctuations of the DM are produced during inflation (or more generally by any Bogoliubov transformation). In such contexts, the ultralight DM instead resides in a squeezed state. In this work, we demonstrate that these two scenarios can be distinguished via the statistics of the DM density fluctuations, such as the matter power spectrum and bispectrum. This provides a probe of the DM state which persists in the limit of large particle number and does not rely on any nongravitational interactions of the DM. Importantly, the statistics of these two states differ when the modes of the squeezed state are all in-phase, as is the case at the end of inflation. Later cosmological dynamics may affect this configuration. Our work motivates future numerical studies of how cosmological dynamics may impact the initial squeezed state and the statistics of its density fluctuations.

We study theories breaking diffeomorphism (Diff) invariance down to the subgroup of transverse diffeomorphisms (TDiff), consisting of multiple scalar fields in a cosmological background. In particular, we focus on models involving a field dominated by its kinetic term and a field dominated by its potential, coupled to gravity through power-law functions of the metric determinant. The Diff symmetry breaking results in the individual energy-momentum tensors not being conserved, although the total conservation law is satisfied. Consequently, an energy exchange takes place between the fields, acting as an effective interaction between them. With this in mind, we consider the covariantized approach to describe the theory in a Diff invariant way but with an additional field and discuss the phenomenological consequences of these models when it comes to the study of the dark sector.

We investigate the impact of one-loop radiative corrections in a nonsupersymmetric model of hybrid inflation with a chaotic (polynomial-like) potential, $V(\varphi )=V_0+{\lambda }_p{\varphi }^p$, in the light of the latest constraints from Planck and Atacama Cosmology Telescope (ACT) observations. Here, $V_0$ denotes the energy scale of inflation, and ${\lambda }_p$ is a coupling associated with the polynomial term of power $p$. These corrections can naturally arise from couplings of the inflaton to other matter fields, which also facilitate the reheating process. At the tree level, the predictions of such models for the scalar spectral index $n_s$ and the tensor-to-scalar ratio $r$ typically lie outside the current observational bounds. However, incorporating one-loop radiative corrections modifies the potential to $V(\varphi )=V_0+{\lambda }_p{\varphi }^p+A{\varphi }^4\ln (\varphi /\mu )$, where $A$ characterizes the strength of the inflaton’s coupling to other fields, and $\mu$ is an appropriate renormalization scale. This radiatively corrected potential can reconcile the model with the combined $\mathrm{Planck}+\mathrm{ACT}$ data over a suitable range of parameter space explored in this work. In particular, radiative corrections from fermionic loops ($A<0$) suppress the tensor-to-scalar ratio $r$, while simultaneously yielding a red-tilted spectrum with $n_s<1$, even for sub-Planckian field excursions. This brings the prediction in line with current observations, while still allowing for potentially detectable signatures of primordial gravitational waves. Furthermore, the inflaton’s couplings enable successful reheating and naturally accommodate nonthermal leptogenesis, providing a unified framework for inflation and baryogenesis.

Understanding the nature of dark matter (DM) particles remains a pivotal challenge in modern cosmology. Current cosmological research on these phenomena primarily utilizes early-universe cosmic microwave background (CMB) observations and other late-time probes, which predominantly focus on large scales. We introduce a novel probe, the 21 cm forest signal, which can be used to investigate DM properties on small scales during the epoch of reionization, thereby addressing the gap left by other cosmological probes. Annihilation and decay of DM particles, as well as Hawking radiation from primordial black holes (PBHs), can heat the intergalactic medium (IGM). This heating suppresses the amplitude of the 21 cm forest 1D power spectrum. Therefore, the 1D power spectrum provides an effective method for constraining DM properties. However, astrophysical heating processes in the early Universe can also affect the 21 cm forest 1D power spectrum. In this work, we assess the potential of using the Square Kilometre Array (SKA) to observe the 21 cm forest 1D power spectrum for constraining DM properties, under the assumption that astrophysical heating can be constrained reliably by other independent probes. Under low astrophysical heating conditions, the 1D power spectrum could constrain the DM annihilation cross section and decay lifetime to $⟨\sigma v⟩\sim {10}^{-31}{\mathrm{cm}}^3{\mathrm{s}}^{-1}$ and $\tau \sim {10}^{30}\mathrm{s}$ for 10 GeV DM particles, and probe PBHs with masses $\sim {10}^{15}\mathrm{g}$ at abundances $f_{\mathrm{PBH}}\simeq {10}^{-13}$. These constraints represent improvements of 5-6 orders of magnitude over current limits. Furthermore, the 21 cm forest 1D power spectrum has the potential to exceed existing bounds on sub-GeV DM and to probe PBHs with masses above ${10}^{18}\mathrm{g}$, which are otherwise inaccessible by conventional cosmological probes. With accumulating observational data and technological advancements, the 21 cm forest emerges as a highly promising tool for probing DM properties.

We propose heavy decaying dark matter (DM) as a new probe of the cosmic neutrino background ($\mathrm{C}\nu \mathrm{B}$). Heavy DM, with mass $\gtrsim {10}^9\mathrm{GeV}$, decaying into neutrinos can be a new source of ultrahigh-energy (UHE) neutrinos. Including this contribution along with the measured astrophysical and predicted cosmogenic neutrino fluxes, we study the scattering of UHE neutrinos with the $\mathrm{C}\nu \mathrm{B}$ via standard weak interactions mediated by the $Z$ boson. We solve the complete neutrino transport equation, taking into account both absorption and reinjection effects, to calculate the expected spectrum of UHE neutrino flux at future neutrino telescopes, such as the IceCube-Gen2 radio. We argue that such observations can be used to probe the $\mathrm{C}\nu \mathrm{B}$ properties and, in particular, local $\mathrm{C}\nu \mathrm{B}$ clustering. We find that, depending on the absolute neutrino mass and the DM mass and lifetime, a local $\mathrm{C}\nu \mathrm{B}$ overdensity $\gtrsim {10}^6$ can be probed at the IceCube-Gen2 radio within ten years of data taking.

The hyperon puzzle refers to the challenge of reconciling the existence of hyperons in neutron star cores and the observed high masses of neutron stars. The recent discovery of PSR J0952-0607 ($2.35\pm 0.17M_{\odot }$) has intensified this challenge. Existing solutions fail to achieve such a high mass and often predict unrealistically fast cooling that is at odds with observations. Here, we propose a novel solution to the hyperon puzzle. Using the Dyson-Schwinger equation approach, we incorporate the quantum many-body effects caused by strong baryon-meson interactions into the equation of state for cold baryonic matter and find it stiff enough to support a maximum hyperon star mass of $M_{\max }\approx 2.59M_{\odot }$, which can explain all the observed high neutron star masses. The resulting proton and hyperon fractions are remarkably low, thus the nucleonic and hyperonic direct Urca processes are significantly suppressed. As a result, fast cooling typically does not occur in ordinary neutron stars.