We revisit the role that gravitational scattering off stars plays in establishing the steady-state distribution of collisionless dark matter (DM) around a massive black hole (BH). This is a physically interesting problem that has potentially observable signatures, such as $\gamma$ rays from DM annihilation in a density spike. The system serves as a laboratory for comparing two different dynamical approaches, both of which have been widely used: a Fokker-Planck treatment and a two-component conduction fluid treatment. In our Fokker-Planck analysis we extend a previous analytic model to account for a nonzero flux of DM particles into the BH, as well as a cutoff in the distribution function near the BH due to relativistic effects or, further out, possible DM annihilation. In our two-fluid analysis, following an approximate analytic treatment, we recast the equations as a “heated Bondi accretion” problem and solve the equations numerically without approximation. While both the Fokker-Planck and two-fluid methods yield basically the same DM density and velocity dispersion profiles away from the boundaries in the spike interior, there are other differences, especially the determination of the DM accretion rate. We discuss limitations of the two treatments, including the assumption of an isotropic velocity dispersion.

A quantity of particular experimental interest is the forward-backward asymmetry in the angular distribution of positively and negatively charged fermions produced in $Z^0$ decays. Measurements of this asymmetry can enable independent determinations of the neutral-current couplings of these fermions, i.e., the $Z^0$ boson couplings for left- and right-handed fermions, respectively. Due to the quark confinement, however, it is difficult to determine the electroweak interactions of quarks, especially for light quarks. In the hadron production electron positron annihilation process, the parton model with factorization theorem gives a reliable approximate description. Quantities are thus expressed in terms of fragmentation functions in the annihilation process. In this paper, we consider the vector meson production in the inclusive electron positron annihilation process and calculate the forward-backward asymmetry in the hadronic level. Calculations are carried out by applying the collinear expansion in the parton model at leading order twist-4. We note here this process provides not only a tool for analyzing the hadronic weak interactions but also an opportunity for understanding the parton model of the strong interaction. In other words, the results can be used to test the electroweak and strong interactions simultaneously.

The link between ordinary Standard Model (SM) photons and both dark photons and axion-like particles (ALPs) can be introduced through the dark axion portal coupling. Given the dark axion portal setup, in the present paper we refer to the dark photon as the mediator between SM and dark matter (DM) particles, implying that it decays predominantly into a pair of DM fermions. Furthermore, we discuss in detail the implication of the dark axion portal scenario for the lepton (electron and muon) fixed-target experiments. In particular, for the specific fixed-target facility we study the missing-energy signatures of the dark photon production followed by its invisible decay into stable DM particles. We investigate the potential to probe dark axion portal vertices with regarding signatures and derive the expected sensitivities of $\mathrm{NA}64e$, $\mathrm{NA}64\mu$, LDMX and ${\mathrm{M}}^3$. Moreover, we estimate the expected reach of $\mathrm{NA}64e$ from the projected statistics of the $J/\psi$ vector meson invisible decays. We also recast the BABAR monophoton bounds for the specific dark axion portal scenario. In addition, we modify the dark axion portal setup by including in the model both the hadron- and lepton-specific ALP couplings. As a result, we obtain the bounds on the combination of fermion-specific couplings of ALP from the fixed-target experiments. We discuss the implication of the modified dark axion portal scenario for the electric dipole moments (EDMs) of SM fermions. In addition, we derive novel constraints on the combination of the $CP$-violating neutron-specific ALP couplings from the existing bounds on neutron EDMs by taking into account the neutron anomalous magnetic moment.

We use lattice QCD to investigate the existence of strong-interaction-stable antiheavy-antiheavy-light-light tetraquarks. We study the $\overline{b}\overline{b}us$ system with quantum numbers $J^P=1^{+}$ as well as the $\overline{b}\overline{c}ud$ systems with quantum numbers $I(J^P)=0(0^{+})$ and $I(J^P)=0(1^{+})$. We carry out computations on five gauge-link ensembles with $2+1$ flavors of domain-wall fermions, including one at the physical pion mass. The bottom quarks are implemented using lattice nonrelativistic QCD, and the charm quarks using an anisotropic clover action. In addition to local diquark-antidiquark and local meson-meson interpolating operators, we include nonlocal meson-meson operators at the sink, which facilitates the reliable determination of the low-lying energy levels. We find clear evidence for the existence of a strong-interaction-stable $\overline{b}\overline{b}us$ tetraquark with binding energy $(-86\pm 22\pm 10)\mathrm{MeV}$ and mass $(10609\pm 22\pm 10)\mathrm{MeV}$. For the $\overline{b}\overline{c}ud$ systems we do not find any indication for the existence of bound states, but cannot rule out their existence either.

In this paper, we propose a new calculation method for the twist-3 gluon Sivers effect within the collinear factorization approach. The method called pole calculation has been used to derive the cross section formula for the single transverse-spin asymmetry as a standard method. We point out that we encounter a problem when we try to apply the pole calculation to the single transverse-spin asymmetry in the heavy quarkonium production whose hadronization mechanism is described by nonrelativistic QCD framework. We show that the new calculation method solves this problem and successfully reproduces known results derived by the pole calculation. Our new method extends the applicability of the twist-3 calculation technique to heavy quarkonium productions that are ideal observables for the investigation of the gluon Sivers effect.

The branching fractions of the decays $B^{+}\to \eta {\ell }^{+}{\nu }_{\ell }$ and $B^{+}\to {\eta }^{\prime }{\ell }^{+}{\nu }_{\ell }$ are measured, where $\ell$ is either an electron or a muon, using a data sample of $711{\mathrm{fb}}^{-1}$ containing $772\times {10}^{6}B\overline{B}$ pairs collected at the $\mathrm{\Upsilon }(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. To reduce the dependence of the result on the form factor model, the measurement is performed over the entire $q^2$ range. The resulting branching fractions are $\mathcal{B}(B^{+}\to \eta {\ell }^{+}{\nu }_{\ell })=(2.83\pm 0.55_{(\mathrm{stat}.)}\pm 0.34_{(\mathrm{syst}.)})\times {10}^{-5}$ and $\mathcal{B}(B^{+}\to {\eta }^{\prime }{\ell }^{+}{\nu }_{\ell })=(2.79\pm 1.29_{(\mathrm{stat}.)}\pm 0.30_{(\mathrm{syst}.)})\times {10}^{-5}$.

A natural broad energy germanium detector is operated in the China Jinping Underground Laboratory for a feasibility study of building the next generation experiment of the neutrinoless double-beta ($0\nu \beta \beta$) decay of ${}^{76}\mathrm{Ge}$. The setup of the prototype facility, characteristics of the broad energy germanium detector, background reduction methods, and data analysis are described in this paper. A background index of $6.4\times {10}^{-3}\mathrm{counts}/(\mathrm{keV}\mathrm{kg}\mathrm{day})$ is achieved and 1.86 times lower than our previous result of the CDEX-1 detector. No signal is observed with an exposure of 186.4 kg day, thus a limit on the half life of ${}^{76}\mathrm{Ge}$ $0\nu \beta \beta$ decay is set at ${\mathrm{T}}_{1/2}^{0\nu }>5.62\times {10}^{22}\mathrm{yr}$ at 90% C.L. The limit corresponds to an effective Majorana neutrino mass in the range of 4.6–10.3 eV, dependent on the nuclear matrix elements.

We study the primordial nucleosynthesis (BBN) in the stepwise scalar field model proposed by Tián [Phys. Rev. D 101, 063531 (2020)], which provides a multiaccelerating Universe solution to the cosmological coincidence problem and predicts that the scalar field may be non-negligible even in the early Universe. The observed abundances of the light elements can be used to constrain the energy density of the scalar field during the BBN era. We present a public matlab code to implement the BBN calculation in the stepwise scalar field model. We show that the model can survive the BBN constraints. In particular, this model incorporates a new solution to the possible deuterium problem: very early dark energy that appears at the end of BBN. In addition, the BBN constraints, along with constraints from the cosmic late-time acceleration, suggest that the Universe in the radiation era evolves in a chaotic accelerating manner, rather than an oscillating scaling manner.

We study the rates and direct $CP$ violations of two-body baryonic ${\overline{B}}_{u,d,s}\to {\mathbf{\text{B}}\overline{\mathbf{\text{B}}}}^{\prime }$ and $B_c^{-}\to {\mathbf{\text{B}}\overline{\mathbf{\text{B}}}}^{\prime }$ decays, where the final state baryons include low-lying octet and decuplet baryons. We incorporate topological amplitude formalism and the factorization approach. Asymptotic relations at large $m_b$ are used to simplify decay amplitudes. Using the most up-to-date data on ${\overline{B}}^0\to p\overline{p}$ and $B^{-}\to \mathrm{\Lambda }\overline{p}$ decay rates as inputs, rates and direct $CP$ violations of ${\overline{B}}_{u,d,s}\to {\mathbf{\text{B}}\overline{\mathbf{\text{B}}}}^{\prime }$ decays are revised and predicted. It is interesting that the results on rates satisfy all existing experimental bounds and some are close to the bounds. Factorization diagrams contribute to penguin-exchange, exchange, annihilation, and penguin-annihilation amplitudes. Although the resulting penguin-exchange factorization amplitudes are sizable, the rest suffer from severe chiral suppression and are sensitive to nonfactorizable contributions. As the ${\overline{B}}_s\to p\overline{p}$ decay is governed by exchange and penguin annihilation amplitudes, the rate predicted in factorization calculation is very rare, but it can be enhanced by including nonfactorizable contributions. The case where the rate is enhanced to saturate the present experimental bound through the enhancement on exchange or penguin-annihilation amplitudes is discussed. As annihilation modes $B_c^{-}\to {\mathbf{\text{B}}\overline{\mathbf{\text{B}}}}^{\prime }$ decays from factorization calculation are found to be very rare, but they can be enhanced by including nonfactorizable contributions as well. Small direct $CP$ violations of pure penguin modes in $\mathrm{\Delta }S=-1$ ${\overline{B}}_{u,d,s}\to {\mathbf{\text{B}}\overline{\mathbf{\text{B}}}}^{\prime }$ decays are robust predictions of the SM, while vanishing direct $CP$ violations of exchange modes in ${\overline{B}}_{u,d,s}\to {\mathbf{\text{B}}\overline{\mathbf{\text{B}}}}^{\prime }$ decays and in all $B_c^{-}\to {\mathbf{\text{B}}\overline{\mathbf{\text{B}}}}^{\prime }$ decay modes are null tests of the SM.

We develop new perturbative tools to accurately study radiatively induced first-order phase transitions. Previous perturbative methods have suffered internal inconsistencies and been unsuccessful in reproducing lattice data, which is often attributed to infrared divergences of massless modes (the Linde problem). We employ a consistent power counting scheme to perform calculations and compare our results against lattice data. We conclude that the consistent expansion removes many previous issues and indicates that the infamous Linde problem is not as big a factor in these calculations as previously thought.

Quantum entanglement provides a novel way to test short distance physics in the nonrelativistic regime. We will provide a protocol to potentially test new physics by bringing two charged massive particle interferometers adjacent to each other. Being charged, the two superpositions will be entangled via electromagnetic interactions mediated by the photons, including the Coulomb and the Casimir-Polder potential. We will bring a method of entanglement based tomography to seek time evolution of very small entanglement phases to probe new physical effects mediated by hitherto unknown macroscopic force which might be responsible for entangling the two charged superpositions modeled by the Yukawa type potential. We will be able to constrain the Yukawa couplings $\alpha \ge {10}^{-35}$ for $r\ge {10}^{-6}\mathrm{m}$ for new physics occurring in the electromagnetic sector, and in the gravitational potential ${\alpha }_g\ge {10}^{-8}$ for $r\ge {10}^{-6}\mathrm{m}$. Furthermore, our protocol can also constrain the axionlike particle mass and coupling, which is complimentary to the existing experimental bounds.

Recent gravitational wave observation based on the data from GW150914 has confirmed Hawking’s area theorem and estimated the increase in total horizon area during a merger process of two Kerr black holes. We use this result and the validity of the second law to obtain the first observational bound on the 4D topological Gauss-Bonnet coupling as $\gamma \lesssim 2.804_{-1.169}^{+7.946}\times {10}^9{\mathrm{m}}^2$ with 95% credibility.

The discrepancies between $b\to s{\ell }^{+}{\ell }^{-}$ data and the corresponding Standard Model predictions constitute one of the most significant hints for new physics currently available. In fact, many scenarios that can account for these anomalies have been proposed in the literature. However, only a single light new physics explanation, i.e., with a mass below the $B$ meson scale, is possible: a light $Z^{\prime }$ boson. In this article, we aim at excluding any light $Z^{\prime }$ model as a solution to $b\to s{\ell }^{+}{\ell }^{-}$ data, using a minimal and conservative setup. Considering the improved limits on $B\to K^{(*)}\nu \nu$, including the experimental sensitivities required for a proper treatment of the necessarily sizable $Z^{\prime }$ width, together with the forthcoming Belle II analyses of $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}+\text{invisible}$, can rule out a $Z^{\prime }$ explanation of $b\to s{\ell }^{+}{\ell }^{-}$ data with a mass below $\approx 4\mathrm{GeV}$. Importantly, such a light $Z^{\prime }$ is the only viable single particle solution to the $b\to s{\ell }^{+}{\ell }^{-}$ anomalies predicting $R(K^{(*)})>0$ in high $q^2$ bins, therefore providing an essential consistency test of data.

Spin correlations of $\mathrm{\Lambda }$-hyperons embedded in the QCD strings formed in high energy collider experiments provide unique insight into their locality and entanglement features. We show from general considerations that, while the Clauser-Horne-Shimony-Holt inequality is less stringent for such states, they provide a benchmark for quantum-to-classical transitions induced by varying (i) the associated hadron multiplicity, (ii) the spin of nucleons, (iii) the separation in rapidity between pairs, and (iv) the kinematic regimes accessed. These studies also enable the extraction of quantitative measures of quantum entanglement. We first explore such questions within a simple model of a QCD string composed of singlets of two partial distinguishable fermion flavors and compare analytical results to those obtained on quantum hardware. We further discuss a class of spin Hamiltonians that model the dynamics of $\mathrm{\Lambda }$ spin correlations. Prospects for extracting quantum features of QCD strings from hyperon measurements at current and future colliders are outlined.

We study the discretization of a Poincaré/Euclidean BF theory. Upon the addition of a boundary term this theory is equivalent to the BFCG theory defined in terms of the Poincaré/Euclidean 2-group. At an intermediate step in the discretization, we note that there are multiple options for how to proceed. One option brings us back to recovering the discrete variables and phase space of the BF theory. Another option allows us to rediscover the phase space related to the $G$ networks given by Asante et al.. Indeed, our main result is that we are now able to relate the continuum fields with the discrete variables shown by Asante et al. This relation is important in determining how to implement the simplicity constraints to recover gravity using the BFCG action. In fact, we show that such a relation is not as simple as in the BF discretization: the discretized variable on the triangles actually depend on several of the continuum fields instead of solely the continuum $B$ field. We also compare and contrast the discretized BF and BFCG models as pairs of of dual 2-groups. This work highlights (again) how the choice of boundary term influences the resulting symmetry structure of the discretized theory—and hence ultimately the choice of quantum states.

We propose a mapping between geometry and kinematics that implies the classical equivalence of any theory of massless bosons—including spin and exhibiting arbitrary derivative or potential interactions—to a nonlinear sigma model (NLSM) with a momentum-dependent metric in field space. From this kinematic metric we construct a corresponding kinematic connection, covariant derivative, and curvature, all of which transform appropriately under general field redefinitions, even including derivatives. We show explicitly how all tree-level on-shell scattering amplitudes of massless bosons are equal to those of the NLSM via the replacement of geometry with kinematics. Lastly, we describe how the recently introduced geometric soft theorem of the NLSM, which universally encodes all leading and subleading soft scalar theorems, also captures the soft photon theorems.

We study the quantum vacuum zero point energy in the Schwarzschild black hole as well as in the Nariai limit of the de Sitter–Schwarzschild backgrounds. We show that the regularized vacuum energy density near the black hole and also in the Nariai setup match exactly with the corresponding value in the flat background, scaling with the fourth power of the mass of the quantum field. The horizon radius of the de Sitter (dS) space created from the vacuum zero point energy introduces a new length scale which should be compared with the black hole horizon radius. There is an upper limiting mass for the black hole immersed in the vacuum zero point energy which is determined by the mass of the Nariai metric associated to the dS background constructed from zero point energy. We calculate the variance in the distribution of the vacuum zero point energy and the density contrast and show that it develops strong inhomogeneities on subhorizon scales.

We investigate the protocol of entanglement harvesting, where two spacelike separated particle detectors extract quantum correlations from a quantum field. Specifically, we analyze the role of the mass of the field and the energy gap of the detectors in the protocol. Perhaps surprisingly, we find that there are regimes in which the entanglement harvested can increase with the mass of the field by decreasing the noise experienced by the detectors. Finally, we study the optimal relationship between the gap of the detectors and the other parameters of the setting that maximizes the entanglement harvested, showing that a small mass can improve the protocol even in this case.

We obtain approximate analytical solutions of the Einstein equations close to the trapping horizon for a dynamical spherically symmetric black hole in the presence of a minimally coupled self-interacting scalar field. This is made possible by a new parametrization of the metric, in which the displacement from the horizon as well as its expansion rate feature explicitly. Our results are valid in a neighborhood of the horizon and hold for any scalar field potential and spacetime asymptotics. An exact equation for the accretion rate is also obtained, which generalizes the standard Bondi formula. We also develop a dynamical system approach to study near-equilibrium black holes; using this formalism, we focus on a simple model to show that the near-equilibrium dynamics is characterized by scaling relations among dynamical variables. Moreover, we show that solutions with purely ingoing energy-momentum flux never reach equilibrium.

We discuss some aspects related to holography of anti–de Sitter (AdS) dyonic hairy black holes, which break the conformal symmetry of the boundary. We use counterterms for the scalar field that satisfies mixed boundary conditions to compute the Euclidean action and dual stress tensor. We apply these results to show that the Cardy-Verlinde formula is not satisfied. However, when the magnetic (or electric) charge vanishes, the conformal symmetry is preserved and the entropy of the black hole can be put in the Cardy-Verlinde form. In our analysis, there is no need of adding extra finite counterterms and, in this particular case, we explicitly show that our results match the ones obtained from using the superpotential as a counterterm.