Using a nonrelativistic constituent quark model in which the degrees of freedom are quark-antiquark and meson-meson components, we have recently shown that the $D^{(*)}K$ thresholds play an important role in lowering the mass of the $c\overline{s}$ states associated with the physical $D_{s0}^{*}(2317)$ and $D_{s1}(2460)$ mesons. This observation is also supported by other theoretical approaches such as lattice-regularized QCD or chiral unitary theory in coupled channels. Herein, we extend our computation to the lowest $P$-wave $B_s$ mesons, taking into account the corresponding $J^P=0^{+}$, $1^{+}$ and $2^{+}$ bottom-strange states predicted by the naive quark model and the $BK$ and $B^{*}K$ thresholds. We assume that mixing with $B_s^{(*)}\eta$ and isospin-violating decays to $B_s^{(*)}\pi$ are negligible. This computation is important because there is no experimental data in the $b\overline{s}$ sector for the equivalent $j_q^P=1/2^{+}$ ($D_{s0}^{*}(2317)$, $D_{s1}(2460)$) heavy-quark multiplet and, as it has been seen in the $c\overline{s}$ sector, the naive theoretical result can be wrong by more than 100 MeV. Our calculation allows us to introduce the coupling with the $D$-wave $B^{*}K$ channel and to compute the probabilities associated with the different Fock components of the physical state.

The longitudinal polarization of a hyperon in $e^{+}{e}^{-}$ annihilation at high energies depends on the longitudinal polarization of the quark produced at the $e^{+}{e}^{-}$ annihilation vertex, whereas the spin alignment of vector mesons is independent of it. They exhibit very different energy dependences. We use the longitudinal polarization of the Lambda hyperon and the spin alignment of $K^{*}$ as representative examples to present numerical results of energy dependences and demonstrate such distinct differences. We present the results at the leading twist with perturbative QCD evolutions of fragmentation functions at the leading order.

The mass and meson-current coupling of the diquark-antidiquark states with the quantum numbers $J^P=0^{+}$ and quark contents $Z_q=[cq][\overline{b}\overline{q}]$ and $Z_s=[cs][\overline{b}\overline{s}]$ are calculated using the two-point QCD sum rule approach. In calculations the quark, gluon, and mixing condensates up to eight dimensions are taken into account. The parameters of the scalar tetraquarks extracted from this analysis are employed to explore the strong vertices $Z_q{B}_c\pi$, $Z_q{B}_c\eta$, and $Z_s{B}_c\eta$ and compute the couplings $g_{Z_q{B}_c\pi }$, $g_{Z_q{B}_c\eta }$, and $g_{Z_s{B}_c\eta }$. The strong couplings are obtained within the soft-meson approximation of the QCD light-cone sum rule method: they form, alongside with other parameters, the basis for evaluating the widths of $Z_q\to B_c\pi$, $Z_q\to B_c\eta$, and $Z_s\to B_c\eta$ decays. Results obtained in this work for the mass of the tetraquarks $Z_q$ and $Z_s$ are compared with available predictions presented in the literature.

The couplings of the isosinglet axial-vector currents to the $\eta$ and ${\eta }^{\prime }$ mesons are evaluated in a stable, model-independent way by use of polynomial kernels in dispersion integrals. The corrections to the Gell-Mann–Oakes–Renner relation in the isoscalar channel are deduced. The derivative of the topological susceptibility at the origin is calculated taking into account instantons and instanton screening.

The exclusive charmonium production process in $\overline{p}p$ annihilation with an associated ${\pi }^0$ meson $\overline{p}p\to J/\psi {\pi }^0$ is studied in the framework of QCD collinear factorization. The feasibility of measuring this reaction through the $J/\psi \to e^{+}{e}^{-}$ decay channel with the AntiProton ANnihilation at DArmstadt ($\overline{\mathsf{P}}\mathsf{ANDA}$) experiment is investigated. Simulations on signal reconstruction efficiency as well as the background rejection from various sources including the $\overline{p}p\to {\pi }^{+}{\pi }^{-}{\pi }^0$ and $\overline{p}p\to J/\psi {\pi }^0{\pi }^0$ reactions are performed with PandaRoot, the simulation and analysis software framework of the $\overline{\mathsf{P}}\mathsf{ANDA}$ experiment. It is shown that the measurement can be done at $\overline{\mathsf{P}}\mathsf{ANDA}$ with significant constraining power under the assumption of an integrated luminosity attainable in four to five months of data taking at the maximum design luminosity.

Using $448.0\times 10^6$ $\psi (3686)$ events collected with the BESIII detector, an amplitude analysis is performed for $\psi (3686)\to \gamma {\chi }_{c1}$, ${\chi }_{c1}\to \eta {\pi }^{+}{\pi }^{-}$ decays. The most dominant two-body structure observed is $a_0(980{)}^{\pm }{\pi }^{\mp }$; $a_0(980{)}^{\pm }\to \eta {\pi }^{\pm }$. The $a_0(980)$ line shape is modeled using a dispersion relation, and a significant nonzero $a_0(980)$ coupling to the ${\eta }^{\prime }\pi$ channel is measured. We observe ${\chi }_{c1}\to a_2(1700)\pi$ production for the first time, with a significance larger than $17\sigma$. The production of mesons with exotic quantum numbers, $J^{PC}=1^{-+}$, is investigated, and upper limits for the branching fractions ${\chi }_{c1}\to {\pi }_1(1400{)}^{\pm }{\pi }^{\mp }$, ${\chi }_{c1}\to {\pi }_1(1600{)}^{\pm }{\pi }^{\mp }$, and ${\chi }_{c1}\to {\pi }_1(2015{)}^{\pm }{\pi }^{\mp }$, with subsequent ${\pi }_1(X{)}^{\pm }\to \eta {\pi }^{\pm }$ decay, are determined.

We study $\mathcal{N}=4$ supersymmetric QED in three dimensions, on a 3-sphere, with $2N$ massive hypermultiplets and a Fayet-Iliopoulos parameter. We identify the exact partition function of the theory with a conical (Mehler) function. This implies a number of analytical formulas, including a recurrence relation and a second-order differential equation, associated with an integrable system. In the large $N$ limit, the theory undergoes a second-order phase transition on a critical line in the parameter space. We discuss the critical behavior and compute the two-point correlation function of a gauge invariant mass operator, which is shown to diverge as one approaches criticality from the subcritical phase. Finally, we comment on the asymptotic $1/N$ expansion and on mirror symmetry.

We show that the linearized higher derivative gravitational field equations are equivalent to an equilibrium condition on the entanglement entropy of small spherical regions in vacuum. This extends Jacobson’s recent derivation of the Einstein equation using entanglement to include general higher derivative corrections. The corrections are naturally associated with the subleading divergences in the entanglement entropy, which take the form of a Wald entropy evaluated on the entangling surface. Variations of this Wald entropy are related to the field equations through an identity for causal diamonds in maximally symmetric spacetimes, which we derive for arbitrary higher derivative theories. If the variations are taken holding fixed a geometric functional that we call the generalized volume, the identity becomes an equivalence between the linearized constraints and the entanglement equilibrium condition. We note that the fully nonlinear higher curvature equations cannot be derived from the linearized equations applied to small balls, in contrast to the situation encountered in Einstein gravity. The generalized volume is a novel result of this work, and we speculate on its thermodynamic role in the first law of causal diamond mechanics, as well as its possible application to holographic complexity.

The effects which quantum fields and an ${\alpha }_0{R}^2$ term in the gravitational Lagrangian have on future singularities are investigated. While all values of ${\alpha }_0$ are considered, an emphasis is placed on those values which are compatible with the universe having undergone Starobinsky inflation in the past. These are also values which lead to stable solutions to the semiclassical backreaction equations in the present universe. The dark energy is modeled as a perfect fluid, and the focus is on type I–IV singularities and little rips which result when the classical Einstein equations are solved with various types of dark energy as a source. First, evidence is provided that the energy densities of massive conformally coupled scalar fields approach that of the conformally invariant scalar field as a type III singularity is approached. Then, solutions to the semiclassical backreaction equations are investigated when conformally invariant fields and the ${\alpha }_0{R}^2$ term in the gravitational Lagrangian are present. General proofs regarding the behaviors of the solutions are given. The proofs are illustrated by analytic and numerical calculations in specific cases.

The recent detection of gravitational waves indicates that stellar-mass black hole binaries are likely to be a key population of sources for forthcoming observations. With future upgrades, ground-based detectors could detect merging black hole binaries out to cosmological distances. Gravitational-wave bursts from high redshifts ($z\gtrsim 1$) can be strongly magnified by gravitational lensing due to intervening galaxies along the line of sight. In the absence of electromagnetic counterparts, the mergers’ intrinsic mass scale and redshift are degenerate with the unknown magnification factor $\mu$. Hence, strongly magnified low-mass mergers from high redshifts appear as higher-mass mergers from lower redshifts. We assess the impact of this degeneracy on the mass-redshift distribution of observable events for generic models of binary black hole formation from normal stellar evolution, Pop III star remnants, or a primordial black hole population. We find that strong magnification ($\mu \gtrsim 3$) generally creates a heavy tail of apparently massive mergers in the event distribution from a given detector. For LIGO and its future upgrades, this tail may dominate the population of intrinsically massive, but unlensed mergers in binary black hole formation models involving normal stellar evolution or primordial black holes. Modeling the statistics of lensing magnification can help account for this magnification bias when testing astrophysical scenarios of black hole binary formation and evolution.

We study several aspects of higher-order gravities constructed from general contractions of the Riemann tensor and the metric in arbitrary dimensions. First, we use the fast-linearization procedure presented in [P. Bueno and P. A. Cano, arXiv:1607.06463] to obtain the equations satisfied by the metric perturbation modes on a maximally symmetric background in the presence of matter and to classify $\mathcal{L}(\mathrm{Riemann})$ theories according to their spectrum. Then, we linearize all theories up to quartic order in curvature and use this result to construct quartic versions of Einsteinian cubic gravity. In addition, we show that the most general cubic gravity constructed in a dimension-independent way and which does not propagate the ghostlike spin-2 mode (but can propagate the scalar) is a linear combination of $f(\mathrm{Lovelock})$ invariants, plus the Einsteinian cubic gravity term, plus a new ghost-free gravity term. Next, we construct the generalized Newton potential and the post-Newtonian parameter $\gamma$ for general $\mathcal{L}(\mathrm{Riemann})$ gravities in arbitrary dimensions, unveiling some interesting differences with respect to the four-dimensional case. We also study the emission and propagation of gravitational radiation from sources for these theories in four dimensions, providing a generalized formula for the power emitted. Finally, we review Wald’s formalism for general $\mathcal{L}(\mathrm{Riemann})$ theories and construct new explicit expressions for the relevant quantities involved. Many examples illustrate our calculations.

CMB and lensing reconstruction power spectra are powerful probes of cosmology. However, they are correlated, since the CMB power spectra are lensed, and the lensing reconstruction is constructed using CMB multipoles. We perform a full analysis of the auto- and cross-covariances, including polarization power spectra and minimum-variance lensing estimators, and compare with simulations of idealized future CMB-S4 observations. Covariances sourced by fluctuations in the unlensed CMB and instrumental noise can largely be removed by using a realization-dependent subtraction of lensing reconstruction noise, leaving a relatively simple covariance model that is dominated by lensing-induced terms and well described by a small number of principal components. The correlations between the CMB and lensing power spectra will be detectable at the level of $\sim 5\sigma$ for a CMB-S4 mission, and neglecting them could underestimate some parameter error bars by several tens of percent. However, we found that the inclusion of external priors or data sets to estimate parameter error bars can make the impact of the correlations almost negligible.

We apply the differential equations technique to the calculation of the one-loop massless diagram with one off-shell leg. Using a reduction to the $\epsilon$-form, we managed to obtain a simple onefold integral representation exact in space-time dimensionality. Expansion of the obtained result in $\epsilon$ and an analytical continuation to the physical region are discussed.

The vectorlike top partners $T$ are predicted in many extensions of the Standard Model (SM). In a simplified model including a single vectorlike $T$ quark with charge $2/3$, we investigate the process $pp\to Tj$ induced by the couplings between the top partner with the first and the third generation quarks at the LHC. We find that the mixing with the first generation can enhance the production cross section. We further study the observability of the single heavy top partner through the process $pp\to T(\to th)j\to t(\to b\ell {\nu }_{\ell })h(\to \gamma \gamma )j$ at the high-luminosity (HL)-LHC (a 14 TeV $pp$ collider with an integrated luminosity of $3{\mathrm{ab}}^{-1}$). For three typical heavy $T$ quark masses $m_T=600$, 800 and 1000 GeV, the $3\sigma$ exclusion limits, as well as the $5\sigma$ discovery reach in the parameter plane of the two variables $g^{*}-R_L$, are respectively obtained at the HL-LHC.

A muon jet ($\mu$-jet) is a very special feature that consists of a cluster of collimated muons from the decay of a fast-moving light particle of mass about $\mathcal{O}(1\mathrm{GeV})$. We will use this feature to search for very light particles from rare decays of the Higgs boson. For such a small angular separation of muons which might come from a long-lived particle, both ATLAS and CMS could have the displaced-vertexing-reconstruction capability. We use two simple models of the Higgs portal type to explore the possibilities of event topologies with two $2\mu$-jets, one $2\mu$-jet and one $4\mu$-jet, and two $4\mu$-jets in the final state at LHC-14. We also summarize existing constraints on these models.

Using deep inelastic scattering on a large nucleus as an example, we consider the transverse momentum broadening of partons in hard processes in the presence of medium. We find that one can factorize the vacuum radiation contribution and medium related $P_T$ broadening effects into the Sudakov factor and medium dependent distributions, respectively. Our derivations can be generalized to other hard processes, such as dijet productions, which can be used as a probe to measure the medium $P_T$ broadening effects in heavy ion collisions when Sudakov effects are not overwhelming.

We point out two mistakes which affect the computation of the moment of inertia and of the tidal Love number in the original paper. Both mistakes have been corrected in Ref. [1] and the correct tidal Love number agrees with the recent computation of Ref. [2].

A cancellation of conformal anomalies in $d=4$ for the $C^2+{\overline{C}}^2$ and of chiral anomalies for the $C^2-{\overline{C}}^2$ is known in $\mathcal{N}$-extended supergravities with $\mathcal{N}\ge 5$. We propose an explanation of these cancellations using supersymmetry and dimension of linearized chiral superfields. We contrast these models with the ones with $\mathcal{N}<5$, where both types of anomalies are known to be present.