We compare precision $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}$ cross section measurements by BESIII in the $E_{\mathrm{cm}}=3.8–4.6\mathrm{GeV}$ range, to predictions based on measured $R_{\mathrm{had}}$ data. The consistency is poor (p-value $<0.012$). Allowing for resonance contributions not seen in $R_{\mathrm{had}}$ gives an excellent fit. The $4.6\sigma$ state required at 4421 MeV suggests that a substantial portion of $\psi (4415)$ decays are not identified, while the $3.2\sigma$ structure at 4211 MeV, if confirmed, points to a new, very narrow resonance. This analysis shows the power of precision $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}$ measurements to uncover or probe otherwise difficult to access states.

The real part of pseudoentropy in conformal field theories is holographically calculated by the area of some extremal spacelike surfaces in the dual de Sitter (dS) and anti–de Sitter (AdS) spacetimes. We show that the flat-space limit of these curves in three-dimensional (A)dS spacetimes is well defined. We find that, if the length of the curves is calculated from the radial coordinate where the retarded time is extremum, then after taking the flat-space limit, the entanglement entropy of the dual theory of three-dimensional flat spacetime is obtained. For dS spacetime, the radial coordinate corresponding to the extremum of retarded time is located inside the cosmological horizon. Our results suggest that, on the field theory side, the entanglement entropy in the dual theory of flat spacetimes should be obtained from the ultrarelativistic limit of pseudoentropy in the dual conformal field theory to (A)dS spacetimes.

In this paper we analytically explore the modularity of the flavored Schur index of 4d $\mathcal{N}=2$ superconformal field theories. We focus on the $A_1$ theories of class-$\mathcal{S}$ and $\mathcal{N}=4$ theories with $SU(N)$ gauge group. We work out the modular orbit of the flavored index and defect index, compute the dimension of the space spanned by the orbit, and provide complete basis for computing modular transformation matrices. The dimension obtained from the flavored analysis predicts the minimal order of the unflavored modular differential equation satisfied by the unflavored Schur index. With the help of modularity, we also study analytically the high temperature asymptotics of the Schur index. In the high temperature limit $\tau \to +i0$, we identified the (defect) Schur index of the genus-zero $A_1$ theories of class $\mathcal{S}$ with the $S^3$ partition function of the $SU(2)\times U(1{)}^n$ star-shaped quiver (with Wilson line insertion). In the identification, we observe an interesting relation between the linear-independence of defect indices and the convergence of the Wilson line partition functions.

Scattering amplitudes for the simplest theory of colored scalar particles—the $\mathrm{Tr}({\mathrm{\Phi }}^3)$ theory—have recently been the subject of active investigations. In this work we describe an unanticipated wider implication of this work: the $\mathrm{Tr}({\mathrm{\Phi }}^3)$ theory secretly contains nonlinear sigma model (NLSM) amplitudes to all loop orders. The NLSM amplitudes are obtained from $\mathrm{Tr}({\mathrm{\Phi }}^3)$ amplitudes by a unique shift of kinematic variables. We show that this shifted kinematics produces amplitudes for a cubic theory with a linear term in the potential, with extrema spontaneously breaking $U(N)\to U(N-k)\times U(k)$. The Goldstone amplitudes for this theory coincide with those of pions in the $U(N)\times U(N)\to U(N)$ chiral Lagrangian to all orders in the planar limit. We also give a purely on-shell understanding of this correspondence, showing that integrands defined by the kinematic shifts have the correct residues on poles and appropriately produce the Adler zero. Finally, we discuss how similar kinematic shifts produce certain infinite classes of mixed amplitudes of pions and $\mathrm{Tr}({\mathrm{\Phi }}^3)$ scalars, most of which are not interpretable from the Lagrangian description.

We present an exact static spherically symmetric solution for the Brans-Dicke action sourced by a self-gravitating massless Klein-Gordon helicity-0 field, which notably possesses an energy-momentum tensor with nonvanishing trace. Through a Weyl mapping into the Einstein frame, the Brans-Dicke scalar field transforms into a “dilaton” that couples with the Klein-Gordon field. Despite this dilatonic coupling, the field equations of the resulting Einstein-Klein-Gordon-dilaton action are fully soluble using the harmonic radial coordinate. Remarkably, in the limit of $\omega \to \infty$, the Brans-Dicke scalar field exhibits an anomalous behavior of $\mathcal{O}(1/\sqrt{\omega })$ as opposed to the expected $\mathcal{O}(1/\omega )$. Consequently, the solution converges to a spacetime configuration of general relativity sourced by the original Klein-Gordon field and a free scalar field, the latter being the $\mathcal{O}(1/\sqrt{\omega })$ “remnant” of the Brans-Dicke scalar field. Although this $\mathcal{O}(1/\sqrt{\omega })$ anomaly was previously identified for Brans-Dicke vacuum and Brans-Dicke-Maxwell electrovacuum, our findings demonstrate its generic applicability in Brans-Dicke gravity, irrespective of the trace of the energy-momentum tensor of the source. We also provide a formal mathematical proof to bolster this conclusion. Furthermore, we discuss the potential implications of the $\mathcal{O}(1/\sqrt{\omega })$ anomaly in improving the relativistic corrections to Newtonian gravity beyond the weak-field parametrized post-Newtonian formalism.

A microscopic nuclear matter formalism with explicit chiral symmetry based on the Nambu–Jona-Lasinio model is considered to describe nuclear matter. To reproduce nuclear matter properties adequately at the saturation density, four-point and eight-point interactions are introduced. Within a Bayesian inference approach, the parameters of the model are determined by imposing nuclear matter, both experimental and from ab initio calculations, and neutron star observational constraints. Nuclear matter properties are well reproduced with an effective mass of 0.75 to 0.8 nucleon mass at the saturation density. At 90% confidence level, the radius of a $1.4M_{\odot }$ star varies between 11.48 and 13.20 km, masses as large as $\sim 2.2M_{\odot }$ are predicted and the radius of a $2M_{\odot }$ star is above 10.5 km. High-density perturbative QCD (pQCD) results exclude equations of state that predict larger maximum masses and radii. The speed of sound increases monotonically with density and reaches values as large as $\sqrt{0.7}c–\sqrt{0.8}c$ in the center of massive stars. Several properties such as the polytropic index or the renormalized trace anomaly, which have been proposed to identify the deconfined phase transition, are analyzed. Interestingly, the radius of the obtained posterior that also meets pQCD constraints aligns closely with the mass-radius measurement of the recent PSR J0437-4715, which contrasts with other relativistic mean field model results.

The axion, as a leading dark matter candidate, is the target of many ongoing and proposed experimental searches based on its coupling to photons. Ultralight axions that couple to photons can also cause polarization rotation of light which can be probed by the cosmic microwave background. In this work, we show that a large axion field is inevitably developed around black holes due to the Bose-Einstein condensation of axions, enhancing the induced birefringence effects. Therefore, measuring the modulation of supermassive black hole imaging polarization angles is a strong probe to the axion-photon coupling due to the formation of the axion condensation (axion star) which enhances the axion field. The oscillating axion field around black holes induces polarization rotation on the black hole image, which is detectable and distinguishable from astrophysical effects on the polarization angle, as it exhibits distinctive temporal variability and frequency invariability. In this work, we perform the theoretical calculation on the axion star formation rate and correspondingly the enhanced axion field value near supermassive black holes. Then, we present the range of axion-photon couplings within the axion mass range ${10}^{-21}–{10}^{-16}\mathrm{eV}$ that can be probed by the Event Horizon Telescope. The axion parameter space probed by black hole polarimetry will expand with the improvement in sensitivity on the polarization measurement and more black hole polarimetry targets with determined black hole masses.

The pulsar timing array community has recently reported the first evidence of a low-frequency stochastic gravitational wave background. With longer observational time spans we expect to be able to resolve individual gravitational wave sources in our data alongside the background signal. The statistical modeling and Bayesian searches for such individual signals is a computationally taxing task that is the focus of many different avenues of methods development. We present a pipeline for performing efficient joint searches for gravitational waves originating from individual supermassive black hole binaries as well as a gravitational wave background using a Hamiltonian Monte Carlo sampling scheme. Hamiltonian sampling proposes samples based on the gradients of the model likelihood, and can both converge faster to more complicated and high-dimensional distributions as well as efficiently explore highly covariant parameter spaces such as the joint gravitational wave background and individual binary model. We show the effectiveness of our scheme by demonstrating accurate parameter estimation for simulated datasets containing low- (6 nHz) or high- (60 nHz) frequency binary sources. Additionally we show that our method is capable at more efficiently generating skymaps for individual binary sources—maps displaying the upper limits on the gravitational wave strain of the source, $h_0$, as a function of sky location—by sampling over larger portions of the full sky. Comparing against results for the NANOGrav 12.5-year dataset, we find similar reconstructed upper limits on the gravitational wave strain while simultaneously reducing the number of required analyses from 72 independent binned searches down to a single run.

We study the high-scale validity of two kinds of two Higgs doublet models (2HDM), namely, type-II and type-X, but with a scalar SU(2) singlet dark matter (DM) candidate in addition in each case. The additional quartic couplings involving the DM particle in the scalar potential in both the scenarios bring in additional constraints from the requirement of perturbative unitarity and vacuum stability. DM relic density and direct search constraints play a crucial role in this analysis as the perturbative unitarity of the DM-Higgs portal couplings primarily decide the high scale validity of the model. We find that, within the parameter regions thus restricted, the type-II scenario must have a cutoff at around ${10}^6\mathrm{GeV}$, while the type-X scenario admits of validity up to the Planck scale. However, only those regions which are valid up to about ${10}^8\mathrm{GeV}$ in type-X 2HDM is amenable to detection at the High-luminosity LHC (up to $3000{\mathrm{fb}}^{-1}$), while most of the parameter space of the type-II scenario mentioned above is likely to be detectable.

We perform a global fit to the electroweak vertices and four-fermion operators of the standard model effective field theory in this work using $N_{\mathrm{eff}}$ from cosmological probes, as well as datasets from colliders and low-energy experiments. We find $N_{\mathrm{eff}}$, both its current measurement and future projections, can only marginally improve the fit in both the flavor universal and the most general flavor scenarios. The resulting $1\sigma$ bound on $N_{\mathrm{eff}}$ is significantly improved from the global fit and becomes comparable to its current theoretical uncertainty, such that the latter will become important for this study at next generation experiments like future lepton colliders. $N_{\mathrm{eff}}$ from the global fit is also adopted to predict the primordial helium abundance $Y_P$, which significantly reduces the parameter space on the $Y_P-N_{\mathrm{eff}}$ plane. Through error propagation, we also conclude that reducing the experimental uncertainty of $Y_P$ from metal-poor galaxies down below 0.2% could play an important role in deepening our understanding of the free neutron lifetime anomaly.

We investigate the determination of the partonic structure of colorless exchanges in deep inelastic diffractive $ep$ scattering at the Electron Ion Collider (EIC), using the standard decomposition into Pomeron and Reggeon contributions. We perform fits to simulated diffractive cross section pseudodata in four variables, including the momentum transfer $t$, to estimate the achievable precision on the Pomeron and Reggeon quark and gluon distributions. We analyze the influence of different cuts in the kinematic variables, beam energy configurations, and luminosities, including a “first year” scenario. We conclude that the EIC will be able to constrain the partonic structure of the subleading Reggeon exchange with a precision comparable to that of the leading Pomeron exchange.

The two excited vector charmonium states $Y(4220)$ and $Y(4360)$ are difficult to understand as pure $c\overline{c}$ charmonium states. Since they are located close to the mass thresholds of $\overline{D}{D}_1$ and ${\overline{D}}^{*}{D}_1$, they can be viewed as $\overline{D}{D}_1$ and ${\overline{D}}^{*}{D}_1$ molecules. Furthermore, recent studies indicate that the exotic states $X(3872)/Z_c(3900)$ and $X_2(4013)/Z_c(4020)$ are the isoscalar/isovector $\overline{D}{D}^{*}$ and isoscalar/isovector ${\overline{D}}^{*}{D}^{*}$ molecules, respectively. In this work, in the molecular picture, we employ the triangle diagram mechanism to study the productions of $Z_c(3900)$ and $X(3872)$ in the pionic and radiative decays of $Y(4220)$, as well as their heavy-quark spin symmetry partners—i.e., the productions of $Z_c(4020)$ and $X_2(4013)$ in the pionic and radiative decays of $Y(4360)$. Using the effective Lagrangian approach, we obtain the ratios of the branching fractions $\mathcal{B}[Y(4360)\to Z_c(4020)\pi ]/\mathcal{B}[Y(4220)\to Z_c(3900)\pi ]=1.2\pm 0.3$ and $\mathcal{B}[Y(4360)\to X_2(4013)\gamma ]/\mathcal{B}[Y(4220)\to X(3872)\gamma ]=0.5\pm 0.1$, almost independent of model parameters, which indicate that the productions of $X_2(4013)$ and $Z_c(4020)$ in the radiative and pionic decays of $Y(4360)$ are likely to be measured in the future. The experimental studies of the predicted decay modes will help to verify the molecular nature of $X(3872)$, $Z_c(3900)$, and $Y(4220)$. We hope that the present work can stimulate experimental and further theoretical studies on these decay modes.

A search is presented for the pair production of heavy vectorlike quarks (VLQs) that each decay into a $W$ boson and a light quark. This study focuses on events where one $W$ boson decays into leptons and the other into hadrons. The search analyzed $140{\mathrm{fb}}^{-1}$ of $pp$ collision data with $\sqrt{s}=13\mathrm{TeV}$, recorded by the ATLAS detector from 2015 to 2018 during run 2 of the Large Hadron Collider. The final state is characterized by a high-transverse-momentum isolated electron or muon, large missing transverse momentum, multiple small-radius jets, and a single large-radius jet identified as originating from the hadronic decay of a boosted $W$ boson. With higher center-of-mass energy and integrated luminosity than in the run 1 search, and improved analysis tools, this analysis excludes VLQs ($Q$) with masses below 1530 GeV at 95% confidence level for the branching ratio $\mathcal{B}(Q\to Wq)=1$, an improvement of 840 GeV on the previous ATLAS limit.

A search for the nonresonant ${\mathrm{\Lambda }}_c^{+}\to p{\mu }^{+}{\mu }^{-}$ decay is performed using proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the LHCb experiment, corresponding to an integrated luminosity of $5.4{\mathrm{fb}}^{-1}$. No evidence for the decay is found in the dimuon invariant-mass regions where the expected contributions of resonances is subdominant. The upper limit on the branching fraction of the ${\mathrm{\Lambda }}_c^{+}\to p{\mu }^{+}{\mu }^{-}$ decay is determined to be $2.9(3.2)\times {10}^{-8}\text{at}90\%(95\%)$ confidence level. The branching fractions in the dimuon invariant-mass regions dominated by the $\eta$, $\rho$ and $\omega$ resonances are also determined.

Recently, radio emission from tidal disruption events (TDEs) has been observed from months to years after the optical discovery. Some of the TDEs including ASASSN-14ae, ASASSN-15oi, AT 2018hyz, and AT 2019dsg are accompanied by the late-time rebrightening phase characterized by a rapid increase in the radio flux. We show that it can be explained by the off-axis two-component jet model, in which the late-time rebrightening arises from the off-axis view of a decelerating narrower jet with an initial Lorentz factor of $\sim 10$ and a jet opening angle of $\sim 0.1\mathrm{rad}$, while the early-time radio emission is attributed to the off-axis view of a wider jet component. We also argue that the rate density of jetted TDEs inferred from these events is consistent with the observations.

We find a new utility of neutrons, usually treated as an experimental nuisance causing unwanted background, in probing new physics signals. The new physics signals can either be radiated from neutrons (neutron bremsstrahlung) or appear through secondary particles from neutron-on-target interactions, dubbed “neutron beam dump.” As a concrete example, we take the FASER/FASER2 experiment as a “factory” of high-energy neutrons that interact with the iron dump. We find that if new physics particles had the same interaction strength to protons and neutrons, their production rate via neutron-initiated bremsstrahlung would be comparable to that via proton-initiated ones, in terms of the resulting flux and the range of couplings that can be probed. The neutron bremsstrahlung can be used, for instance, to probe dark gauge bosons with nonzero neutron coupling. In particular, we investigate protophobic gauge bosons and find that FASER/FASER2 can probe new parameter space. We also illustrate the possibility of neutron-induced secondary particles by considering axionlike particles with electron couplings. We conclude that the physics potential of FASER/FASER2 in terms of new physics searches can be greatly extended and improved with the inclusion of neutron interactions.

A new approach for operationally studying the effects of spacetime in quantum superpositions of semiclassical states has recently been proposed by some of the authors. This approach was applied to the case of a ($2+1$)-dimensional Bañados-Teitelboim-Zanelli (BTZ) black hole in a superposition of masses, where it was shown that a two-level system interacting with a quantum field residing in the spacetime exhibits resonant peaks in its response at certain values of the superposed masses. Here, we extend this analysis to a mass-superposed rotating BTZ black hole, considering the case where the two-level system corotates with the black hole in a superposition of trajectories. We find similar resonances in the detector response function at rational ratios of the superposed outer horizon radii, specifically in the case where the ratio of the inner and outer horizons is fixed. This suggests a connection with Bekenstein’s seminal conjecture concerning the discrete horizon spectra of black holes in quantum gravity, generalized to the case of rotating black holes. Our results further indicate that deeper insights into quantum-gravitational phenomena may be accessible via tools in relativistic quantum information and curved spacetime quantum field theory.

We characterize the quantum states dual to entanglement wedges in arbitrary spacetimes, in settings where the matter entropy can be neglected compared to the geometric entropy. In AdS/CFT, such states obey special entropy inequalities known as the holographic entropy cone. In particular, the mutual information of CFT subregions is monogamous (MMI). We extend this result to arbitrary spacetimes, using a recent proposal for the generalized entanglement wedge $e(a)$ of a gravitating region $a$. Given independent input regions $a$, $b$, and $c$, we prove MMI: $\mathrm{Area}[e(a)]+\mathrm{Area}[e(b)]+\mathrm{Area}[e(c)]-\mathrm{Area}[e(ab)]-\mathrm{Area}[e(bc)]-\mathrm{Area}[e(ca)]+\mathrm{Area}[e(abc)]\le 0$. We expect that the full holographic entropy cone can be extended to arbitrary spacetimes using similar methods.

The dimer tiling problem asks in how many ways can the edges of a graph be covered by dimers so that each site is covered once. In the special case of a planar graph, this problem has a solution in terms of a free fermionic field theory. We rediscover and explore an expression for the number of coverings of an arbitrary graph by arbitrary objects in terms of an interacting fermionic field theory first proposed by Samuel. Generalizations of the dimer tiling problem, which we call “dimer piling problems,” demand that each site be covered $N$ times by indistinguishable dimers. Our field theory provides a solution of these problems in the large-$N$ limit. We give a similar path integral representation for certain lattice coloring problems.

Tidal interactions play a crucial role in deciphering gravitational wave signals emitted by the coalescence of binary systems. They are usually quantified by a set of complex coefficients which include tidal Love numbers, describing the conservative response to an external perturbation. In the static case, these are found to vanish exactly for asymptotically flat black holes in general relativity in four space-time dimensions, and recently they have been generalized to dynamical interactions. In the context of response theory, the retarded Green’s function provides the complete description of the behavior of dynamical systems. In this work we investigate the relation between Love numbers and Green’s functions, and highlight the relevance of radiation reaction effects to their connection. As a special case, we discuss Banados-Teitelboim-Zanelli black holes, where the absence of radiative modes allows us to make a direct link between them.