We discuss a nonfactorizable (NF) contribution of a charm loop to the FCNC $B$-decay amplitude given through the three-particle Bethe-Salpeter amplitude (3BS) of the $B$-meson. This 3BS contains one heavy-quark field and two light fields (a light quark and a gluon). Our discussion is aimed at clarifying properties of the $B$-meson 3BS necessary to describe properly charm-loop contributions to the amplitudes of FCNC $B$-decays. We demonstrate that the dominant contribution of nonfactorizable charm to FCNC $B$-decay amplitude is given in the heavy-quark limit by a convolution of some hard kernel and the $B$-meson 3BS in a “double-collinear” light cone (LC) configuration: one of the light degrees of freedom $\varphi (x)$, $x^2=0$, lies on the ($+$)-direction of the LC, whereas another light degree of freedom ${\varphi }^{\prime }(x^{\prime })$, $x^{\prime 2}=0$ lies along the ($-$)-direction. We show the emergence of new constraints on the distribution amplitudes which parametrize the 3BS in this double-collinear configuration.

This paper presents a systematic investigation of the electromagnetic properties of the hidden-charm molecular pentaquarks within the constituent quark model. Specifically, it focuses on two types of pentaquarks; the ${\mathrm{\Xi }}_c^{(\prime ,*)}{\overline{D}}_s^{*}$-type pentaquarks with double strangeness and the ${\mathrm{\Omega }}_c^{(*)}{\overline{D}}_s^{*}$-type pentaquarks with triple strangeness. The study explores various electromagnetic properties, including the magnetic moments, the transition magnetic moments, and the radiative decay behavior of these pentaquarks. To ensure realistic calculations, the $S\text{−}D$ wave mixing effect and the coupled-channel effect are taken into account. By examining the electromagnetic properties of the hidden-charm molecular pentaquarks with double and triple strangeness, this research contributes to the deeper understanding of their spectroscopic behavior. These findings form a valuable addition to the ongoing investigation into the broader spectrum of properties exhibited by the hidden-charm molecular pentaquarks.

We investigate the consequences of models where dark sector quarks could be produced at the LHC, which subsequently undergo a dark parton shower, generating jets of dark hadrons that ultimately decay back to Standard Model hadrons. This yields collider objects that can be nearly indistinguishable from Standard Model jets, motivating the reliance on substructure observables to tease out the signal. However, substructure predictions are sensitive to the details of the incalculable dark hadronization. We show that the Lund jet plane provides a very effective tool for designing observables that are resilient against the unknown impact of dark hadronization on the substructure properties of dark sector jets.

Jet fragmentation functions are measured for the first time in proton-proton collisions for charged pions, kaons, and protons within jets recoiling against a $Z$ boson. The charged-hadron distributions are studied longitudinally and transversely to the jet direction for jets with transverse momentum $20<p_{\mathrm{T}}<100\mathrm{GeV}$ and in the pseudorapidity range $2.5<\eta <4$. The data sample was collected with the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of $1.64{\mathrm{fb}}^{-1}$. Triple differential distributions as a function of the hadron longitudinal momentum fraction, hadron transverse momentum, and jet transverse momentum are also measured for the first time. This helps constrain transverse-momentum-dependent fragmentation functions. Differences in the shapes and magnitudes of the measured distributions for the different hadron species provide insights into the hadronization process for jets predominantly initiated by light quarks.

Generalized quasitopological gravities (GQTGs) are higher-order extensions of Einstein gravity in $D$ dimensions satisfying a number of interesting properties, such as possessing second-order linearized equations of motion on top of maximally symmetric backgrounds, admitting nonhairy generalizations of the Schwarzschild-Tangherlini black hole which are characterized by a single metric function or forming a perturbative spanning set of the space of effective theories of gravity. In this work, we classify all inequivalent GQTGs at all curvature orders $n$ and spacetime dimension $D\ge 4$. This is achieved after the explicit construction of a dictionary that allows the uplift of expressions evaluated on a single-function static and spherically symmetric ansatz into fully covariant ones. On the one hand, applying such prescription for $D\ge 5$, we find the explicit covariant form of the unique inequivalent quasitopological gravity that exists at each $n$ and, for the first time, the covariant expressions of the $n-2$ inequivalent proper GQTGs existing at every curvature order $n$. On the other hand, for $D=4$, we are able to provide the first rigorous proof of the fact that there is one, and only one, (proper) inequivalent GQTG at each curvature order $n$, deriving along the way a simple expression for such four-dimensional representative at every order $n$.

The Kramers-Kronig relation is a well-known relation, especially in the field of optics. The key to this relation is the causality that output comes only after input. We first show that gravitational lensing obeys the causality in the sense that (electromagnetic/gravitational) waves emitted from the source arrive at an observer only after the arrival of the signal in geometrical optics. This is done by extending the previous work which is based on the thin lens approximation. We then derive the Kramers-Kronig relation in gravitational lensing, as the relation between real and imaginary parts of the amplification factor, which is the amplitude ratio of the lensed wave to the unlensed wave. As a by-product, we find a new relation that equates integration of the square of the real part of the amplification factor over frequency to that for the imaginary part of the amplification factor. We also obtain a sum rule which relates the integral of the imaginary part of the amplification factor with the magnification of the first arrival image in geometrical optics. Finally, we argue that an incorrect separation of the observed gravitational waveform into the amplification factor and the unlensed waveform generically leads to the violation of the Kramers-Kronig relation. Our work suggests that examining the violation of the Kramers-Kronig relation may be used for correctly extracting the lensing signal in the gravitational wave observations.

As a possible alternative to black holes, horizonless compact objects have significant implications for gravitational-wave physics. In this work, we utilize the standard linearized theory of general relativity to calculate the quadrupolar tidal Love numbers of a nonexotic compact object with a thin shell proposed by Rosa and Piçarra. It is found that both types of tidal Love numbers are positive and increase with the initial radius for almost all values of the compactness parameter. Furthermore, they have an unexpected upper bound and vanish in the most compact configurations. As a result, this model is indeed a suitable mimicker of a black hole. However, we also observed that the speed of sound within the fluid on the shell diverges in the black hole limit.

The Standard Model Higgs potential may become unbounded from below at large field values $h\gtrsim h_{\mathrm{top}}\sim {10}^{10}\mathrm{GeV}$, with important cosmological implications. For a potential of this form, the commonly assumed scenario of a nucleated thin-wall bubble driving the transition from the electroweak vacuum to the unstable region does not apply. We present exact analytical solutions for potentials that have the same qualitative form as the Higgs potential. They show that the transition is driven by a thick-wall spherical bubble of true vacuum, with a surface that expands at asymptotically the speed of light. A “crunch” singularity appears in the quasi-anti–de Sitter interior, with the collapsed region also expanding at asymptotically the speed of light. The singularity is surrounded by a region of trapped surfaces whose boundary forms an apparent horizon. An event horizon separates the singularity from the bubble exterior, so that the expansion of the bubble surface is not affected by the collapse of the interior. The solutions provide exact descriptions of the geometry for thick-wall bubbles and are consistent with the analysis of Espinosa et al. [J. High Energy Phys. 09 (2015) 174.] and Strumia-Tetradis [J. High Energy Phys. 09 (2022) 203.] for the Higgs potential.

We study the azimuthal asymmetries in back-to-back leptoproduction of the $D$ meson and jet to probe the gluon TMDs in an unpolarized and transversely polarized electron-proton collision at the kinematics of electron-ion collider (EIC). We give predictions for unpolarized cross sections within the TMD factorization framework. In $D$-meson and jet formation, the only leading order contribution comes from the photon gluon fusion process. We give numerical estimates of the upper bound on the azimuthal asymmetries with the saturation of positivity bounds; also, we present the asymmetries using a Gaussian parametrization of TMDs. We obtain sizable asymmetries in the kinematics that will be accessible at EIC.

Based on $22.7{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ annihilation data collected at 33 different center-of-mass energies between 3.7730 and 4.7008 GeV with the BESIII detector at the BEPCII collider, Born cross sections of the two processes $e^{+}{e}^{-}\to \varphi K^{+}{K}^{-}$ and $e^{+}{e}^{-}\to \varphi K_S^0{K}_S^0$ are measured for the first time. No indication of resonant production through an intermediate vector state $V$ is observed, and the upper limits on the product of the electronic width ${\mathrm{\Gamma }}_{e^{+}{e}^{-}}$ and the branching fraction $\mathrm{Br}(V\to \varphi K\overline{K})$ of the processes $e^{+}{e}^{-}\to V\to \varphi K^{+}{K}^{-}$ and $e^{+}{e}^{-}\to V\to \varphi K_S^0{K}_S^0$ at the 90% confidence level are obtained for a large parameter space in resonance masses and widths. For the current world average mass and width of the $\psi (4230)$ of $m=4.2187\mathrm{GeV}/c^2$ and $\mathrm{\Gamma }=44\mathrm{MeV}$, we set upper limits on the $\varphi K^{+}{K}^{-}$ and $\varphi K_S^0{K}_S^0$ final states of 1.75 and 0.47 eV at the 90% confidence level, respectively.

Quantum-correlated $D\overline{D}$ pairs collected by the BESIII experiment at the $\psi (3770)$ resonance corresponding to an integrated luminosity of $2.93{\mathrm{fb}}^{-1}$ are used to study the $D^0\to K_S^0{\pi }^{+}{\pi }^{-}{\pi }^0$ decay mode. The $CP$-even fraction of $D^0\to K_S^0{\pi }^{+}{\pi }^{-}{\pi }^0$ decays is determined to be $0.235\pm 0.010\pm 0.002$, where the first uncertainty is statistical and the second is systematic.

A search for $K_{\mathrm{S}(\mathrm{L})}^0\to {\mu }^{+}{\mu }^{-}{\mu }^{+}{\mu }^{-}$ decays is performed using proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of $5.1{\mathrm{fb}}^{-1}$. No evidence for signal is found. The 90% confidence level upper limits are the first set for both decays and are $\mathcal{B}(K_{\mathrm{S}}^0\to {\mu }^{+}{\mu }^{-}{\mu }^{+}{\mu }^{-})<5.1\times {10}^{-12}$ and $\mathcal{B}(K_{\mathrm{L}}^0\to {\mu }^{+}{\mu }^{-}{\mu }^{+}{\mu }^{-})<2.3\times {10}^{-9}$.

Based on $e^{+}{e}^{-}$ collision data corresponding to an integrated luminosity of $4.5{\mathrm{fb}}^{-1}$ collected at the center-of-mass energies between 4.600 and 4.699 GeV with the BESIII detector at BEPCII, the absolute branching fraction of the inclusive decay ${\overline{\mathrm{\Lambda }}}_c^{-}\to \overline{n}+X$, where $X$ refers to any possible final state particles, is measured. The absolute branching fraction is determined to be $\mathcal{B}({\overline{\mathrm{\Lambda }}}_c^{-}\to \overline{n}+X)=(32.4\pm 0.7\pm 1.5)\%$, where the first uncertainty is statistical and the second systematic. Assuming $CP$ symmetry, the measurement indicates that about one fourth of ${\mathrm{\Lambda }}_c^{+}$ (${\overline{\mathrm{\Lambda }}}_c^{-}$) decay modes with a neutron (an antineutron) in the final state have not been observed.

We consider general torsion components in three-dimensional Einstein-Cartan gravity, providing a geometrical interpretation for matter, and find new solutions of the corresponding equations for the Riemann curvature and torsion. These geometries involve a peculiar interplay between the vector $({\beta }_i)$ and the singlet ($\tau$) irreducible components of the torsion which, under general conditions, feature a formal analogy with the equation for a Beltrami fluid. Interestingly, we find that the local ${\mathrm{AdS}}_3$ geometry is now deformed by effect of the “Beltrami-torsion” ${\beta }_i$. Some of these new solutions describe deformations of the Bañados, Teitelboim, Zanelli black hole due to the presence of torsion. The latter acts as a geometric flux which, in some cases, removes the causal singularity.

We present the exact solutions of the homoclinic orbits for the timelike geodesics of the particle on the general nonequatorial orbits in the Kerr-Newman black holes. The homoclinic orbit is the separatrix between bound and plunging geodesics, a solution that asymptotes to an energetically bound, unstable spherical orbit. The solutions are written in terms of the elliptical integrals and the Jacobi elliptic functions of manifestly real functions of the Mino time where we focus on the effect from the charge of the black hole to the homoclinic orbits. The parameter space of the homoclinic solutions is explored. The nonequatorial homoclinic orbits in Kerr cases can be obtained by setting the charge of the black holes to be zero. The homoclinic orbits and the associated phase portrait as a function of the radial position and its derivation with respect to the Mino time are plotted using the analytical solutions. In particular, the solutions can reduce to homoclinic orbits with zero azimuthal angular momentum, providing insights into the effects of frame dragging from the spin as well as the charge of the black hole. The implications of the obtained results to observations are discussed.

We study the generalized free energy of the five dimensional charged Gauss-Bonnet anti–de Sitter (AdS) black holes in the grand canonical ensemble by treating the black hole radius and the charge as the order parameters. On the two dimensional free energy landscape, the lowest points in the basins represent the local stable black holes and the saddle point represents the unstable black hole. We show that the black hole is the topological defect of gradient field of the landscape. The black hole stability is determined by the topography of the free energy landscape in terms of the basin depths and the barrier height between the basins and is not by the topology of the gradient field. In addition, we study the stochastic dynamics of the black hole phase transition and obtain the dominant kinetic path for the transition on the free energy landscape. Unlike the one dimensional landscape, the dominant kinetic path between the small and the large black hole state does not necessarily pass through the intermediate black hole state. Furthermore, the inhomogeneity in diffusions can lead to the switching from the coupled cooperative process of black hole phase transition to the decoupled sequential process, giving different kinetic mechanisms.

We perform a Markov Chain Monte Carlo analysis of a simple yet generic multifield inflation model characterized by two scalar fields coupled to each other and nonminimally coupled to gravity, fit to Planck 2018 cosmic microwave background (CMB) data. In particular, model parameters are constrained by data on the amplitude of the primordial power spectrum of scalar curvature perturbations on CMB scales $A_s$, the spectral index $n_s$, and the ratio of power in tensor to scalar modes $r$, with a prior that the primordial power spectrum should also lead to primordial black hole (PBH) production sufficient to account for the observed dark matter abundance. We find that $n_s$ in particular controls the constraints on our model. Whereas previous studies of PBH formation from an ultraslow-roll phase of inflation have highlighted the need for at least one model parameter to be highly fine-tuned, we identify a degeneracy direction in parameter space such that shifts by $\sim 10\%$ of one parameter can be compensated by comparable shifts in other parameters while preserving a close fit between model predictions and observations. Furthermore, we find this allowed parameter region produces observable gravitational wave signals in the frequency ranges to which upcoming experiments are projected to be sensitive, including Advanced LIGO and Virgo, the Einstein Telescope, Cosmic Explorer, DECIGO, and LISA.

Over the past decade, the kinematic Sunyaev-Zel’dovich (kSZ) effect has emerged as an observational probe of the distribution of baryons and velocity fields in the late Universe. Of the many ways to detect the kSZ, the “projected-fields kSZ estimator” has the promising feature of not being limited to galaxy samples with accurate redshifts. The current theoretical modeling of this estimator involves an approximate treatment only applicable at small scales. As the measurement fidelity rapidly improves, we find it necessary to move beyond the original treatment and hence derive an improved theoretical model for this estimator without these previous approximations. We show that the differences between the predicted signal from the two models are scale-dependent and will be significant for future measurements from the Simons Observatory and CMB-S4 in combination with galaxy data from WISE or the Rubin Observatory, which have high forecasted signal-to-noise ratios ($>100$). Thus, adopting our improved model in future analyses will be important to avoid biases. Equipped with our model, we explore the cosmological dependence of this kSZ signal for future measurements. With a Planck prior, residual uncertainty on $\mathrm{\Lambda }\mathrm{CDM}$ parameters leads to $\sim 7\%$ marginalized uncertainties on the signal amplitude, compared to a subpercent level forecasted with a fixed cosmology. To illustrate the potential of this kSZ estimator as a cosmological probe, we forecast initial constraints on $\mathrm{\Lambda }\mathrm{CDM}$ parameters and the sum of neutrino masses, paving the way for jointly fitting both baryonic astrophysics and cosmology in future analyses.

Primordial black holes (PBHs) have recently attracted much attention, as they may explain some of the LIGO/Virgo/KAGRA observations and significantly contribute to the dark matter in our Universe. The next generation of gravitational wave detectors will have the unique opportunity to set stringent bounds on this putative population of objects. Focusing on the Einstein Telescope (ET), in this paper we analyze in detail the impact of systematics and different detector designs on our future capability of observing key quantities that would allow us to discover and/or constrain a population of PBH mergers. We also perform a population analysis, with a mass and redshift distribution compatible with the current observational bounds. Our results indicate that ET alone can reach an exquisite level of accuracy on the key observables considered as well as detect up to tens of thousands of PBH binaries per year (for an optimistic PBH population that saturates current upper bounds on the abundance), but for some key signatures—in particular, high-redshift sources—the cryogenic instrument optimized for low frequencies turns out to be crucial, for both the number of observations and the error on the parameter reconstruction. As far as the detector geometry is concerned, we find that a network consisting of two separated $\mathsf{L}$-shaped interferometers of 15 (20) km arm length, oriented at 45° with respect to each other, performs better than a single triangular-shaped instrument of 10 (15) km arm length, for all the metrics considered.

The cosmological constant presents one of the most fascinating and confounding problems in physics. A straightforward, seemingly robust prediction of quantum mechanics and general relativity is that the vacuum energy gravitates. Therefore, the cosmological constant should be enormous. It is minuscule. Since there is no understanding of why the cosmological constant is so small, it is important to test this idea in many different situations. In particular, given the span of distances in astronomy and particle physics, it is vital to test the gravitation of vacuum energy on as many distance scales as we can. Rydberg atoms open up a new set of distances for exploration. It is satisfying to measure the cosmological constant with an atom, but its main significance is extending measurements to microscopic distances. Here, too, there is no evidence of the gravitation of the vacuum. At scales of a micron and less, we place a limit of 7 GeV on the scale of gravitating vacuum energy, well below the scale of 100 GeV of the Standard Model of particle physics.