The self-lensing of a massive black hole binary (MBHB), which occurs when the two BHs are aligned close to the line of sight, is expected to produce periodic, short-duration flares. Here we study the shapes of self-lensing flares (SLFs) via general-relativistic ray tracing in a superimposed binary BH metric, in which the emission is generated by geometrically thin accretion flows around each component. The suite of models covers eccentric binary orbits, black hole spins, unequal mass binaries, and different emission model geometries. We explore the above parameter space and report how the light curves change as a function of, e.g., binary separation, inclination, and eccentricity. We also compare our light curves to those in the microlensing approximation, and show how strong deflections, as well as time-delay effects, change the size and shape of the SLF. If gravitational waves (GWs) from the inspiraling MBHB are observed by LISA, SLFs can help securely identify the source and localizing it on the sky, and to constrain the graviton mass by comparing the phasing of the SLFs and the GWs. Additionally, when these systems are viewed edge-on the SLF shows a distinct dip that can be directly correlated with the BH shadow size. This opens a new way to measure BH shadow sizes in systems that are unresolvable by current VLBI facilities.

The leptonic and inclusive hadronic decay branching fractions of the $W$ boson are measured using proton-proton collision data collected at $\sqrt{s}=13\mathrm{TeV}$ by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of $35.9{\mathrm{fb}}^{-1}$. Events characterized by the production of one or two $W$ bosons are selected and categorized based on the multiplicity and flavor of reconstructed leptons, the number of jets, and the number of jets identified as originating from the hadronization of $b$ quarks. A binned maximum likelihood estimate of the $W$ boson branching fractions is performed simultaneously in each event category. The measured branching fractions of the $W$ boson decaying into electron, muon, and tau lepton final states are $(10.83\pm 0.10)\%$, $(10.94\pm 0.08)\%$, and $(10.77\pm 0.21)\%$, respectively, consistent with lepton flavor universality for the weak interaction. The average leptonic and inclusive hadronic decay branching fractions are estimated to be $(10.89\pm 0.08)\%$ and $(67.32\pm 0.23)\%$, respectively. Based on the hadronic branching fraction, three standard model quantities are subsequently derived: the sum of squared elements in the first two rows of the Cabibbo–Kobayashi–Maskawa (CKM) matrix ${\sum }_{ij}{|V_{ij}|}^2=1.984\pm 0.021$, the CKM element $|V_{cs}|=0.967\pm 0.011$, and the strong coupling constant at the $W$ boson mass scale, ${\alpha }_{\mathrm{S}}(m_W^2)=0.095\pm 0.033$.

We have performed a combined analysis of the BESIII data for both the $Z_c(3900)$ and $Z_{cs}(3985)$ structures, assuming that the latter is an SU(3) flavor partner of the former one. We have improved on the previous analysis of Albaladejo et al. [Phys. Lett. B 755, 337 (2016)] by computing the amplitude for the $D_1\overline{D}{D}^{*}$ triangle diagram considering both $D$- and $S$-wave $D_1{D}^{*}\pi$ couplings. We have also investigated effects from SU(3) light-flavor violations, which are found to be moderate and of the order of 20%. The successful reproduction of the BESIII spectra, in both the hidden-charm and hidden-charm strange sectors, strongly supports that the $Z_{cs}(3985)$ and $Z_c(3900)$ are SU(3) flavor partners placed in the same octet multiplet. The best results are obtained when an energy-dependent term in the diagonal $D^{(*)}{\overline{D}}_{(s)}^{(*)}$ interaction is included, leading to resonances (poles above the thresholds) to describe these exotic states. We have also made predictions for the isovector $Z_c^{*}$ and isodoublet $Z_{cs}^{*}$, $D^{*}{\overline{D}}^{*}$, and $D^{*}{\overline{D}}_s^{*}$ molecules, with $J^{PC}=1^{+-}$ and $J^P=1^{+}$, respectively. These states would be heavy-quark spin symmetry (HQSS) partners of the $Z_c$ and $Z_{cs}$. Besides the determination of the masses and widths of the $Z_c(3900)$ and $Z_{cs}(3985)$, we also predict those of the $Z_c^{*}$ and $Z_{cs}^{*}$ resonances.

We derive a quantum kinetic theory for QED based on Kadanoff-Baym equations for Wigner functions. By assuming parity invariance and considering a complete set of self-energy diagrams, we find that the resulting kinetic theory expanded to lowest order in $\hslash$ generalizes the well-known classical kinetic theory to the massive case. It contains elastic and inelastic collision terms and integrates a screening effect naturally. For a given solution to the classical kinetic theory, we find at next order in $\hslash$ a nondynamical quantum correction to Wigner functions for both fermions and photons, which gives rise to spin polarization for fermions and photons, respectively. The approach allows us to study the nondynamical part of the collisional effect on the spin polarization phenomenon.

A promising way to measure the distribution of matter on small scales ($k\sim 10h{\mathrm{Mpc}}^{-1}$) is to use gravitational lensing of the cosmic microwave background (CMB). CMB-HD, a proposed high-resolution, low-noise millimeter survey over half the sky, can measure the CMB lensing auto spectrum on such small scales enabling measurements that can distinguish between a cold dark matter (CDM) model and alternative models designed to solve problems with CDM on small scales. However, extragalactic foregrounds can bias the CMB lensing auto spectrum if left untreated. We present a foreground mitigation strategy that provides a path to reduce the bias from two of the most dominant foregrounds, the thermal Sunyaev-Zel’dovich effect and the cosmic infrared background. Given the level of realism included in our analysis, we find that the thermal Sunyaev-Zel’dovich alone and the cosmic infrared background alone bias the lensing auto spectrum by $0.6\sigma$ and $1.1\sigma$, respectively, in the lensing multipole range of $L\in [5000,20000]$ for a CMB-HD survey; combined these foregrounds yield a bias of only $1.3\sigma$. Including these foregrounds, we also find that a CMB-HD survey can distinguish between a CDM model and a ${10}^{-22}\mathrm{eV}$ fuzzy dark matter model at the $5\sigma$ level. These results provide an important step in demonstrating that foreground contamination can be sufficiently reduced to enable a robust measurement of the small-scale matter power spectrum with CMB-HD.

Hydrogen deuteride (HD) is prevalent in a wide variety of astrophysical environments, and measuring its large-scale distribution at different epochs can, in principle, provide information about the properties of these environments. In this paper we explore the prospects for accessing this distribution using line-intensity mapping of emission from the lowest rotational transition in HD, focusing on observations of the epoch of reionization ($z\sim 6–10$) and earlier. We find the signal from the epoch of reionization to be most promising, through cross correlations within existing [CII] intensity mapping surveys. While the signal we predict is out of reach for current-generation projects, planned future improvements should be able to detect reionization-era HD without any additional observations, and would help to constrain the properties of the star-forming galaxies thought to play a key role in reionization. We also investigate several avenues for measuring HD during “cosmic dawn” ($z\sim 10–30$), a period in which HD could provide one of the only complementary observables to 21 cm intensity maps. We conclude that existing and planned facilities are poorly matched to the specifications desirable for a significant detection, though such a measurement may be achievable with sustained future effort. Finally, we explain why HD intensity mapping of the intergalactic medium during the cosmic dark ages ($z\gtrsim 30$) appears to be out of reach of any conceivable experiment.

We proposed a recipe to systematically calculate Feynman integrals containing linear propagators using the auxiliary mass flow method. The key of the recipe is to introduce a quadratic term for each linear propagator and then using differential equations to get rid of their effects. As an application, we calculated all master integrals of vacuum integrals containing a gauge link up to four loops, and we checked the results by nontrivial dimensional recurrence relations.

It is expected that infinite distance limits in the moduli space of quantum gravity are accompanied by a tower of light states. In view of the emergent string conjecture, this tower must either induce a decompactification or correspond to the emergence of a tensionless critical string. We study the consistency conditions implied by this conjecture on the asymptotic behavior of quantum gravity under dimensional reduction. If the emergent string descends from a ($2+1$)-dimensional membrane in a higher-dimensional theory, we find that such a membrane must parametrically decouple from the Kaluza-Klein scale. We verify this censorship against emergent membrane limits, where the membrane would sit at the Kaluza-Klein scale, in the hypermultiplet moduli space of Calabi-Yau 3-fold compactifications of string/M-theory. At the classical level, a putative membrane limit arises, up to duality, from an M5-brane wrapping the asymptotically shrinking special Lagrangian 3-cycle corresponding to the Strominger-Yau-Zaslow fiber of the Calabi-Yau. We show how quantum corrections in the moduli space obstruct such a limit and instead lead to a decompactification to 11 dimensions, where the role of the M5- and M2-branes are interchanged.

It is commonly believed that neutron stars exceeding the maximum mass limit for stability could be formed in the aftermath of binary neutron star mergers, enjoying a short life of metastability before losing centrifugal support and collapsing to a black hole. It is suggested here that a similar scenario could take place when the remnant’s excess mass is supported by an ultrastrong ($\gtrsim {10}^{17}\mathrm{G}$) magnetic field that could be generated during, and shortly after, coalescence. We show that such “magnetically supramassive” neutron stars could stave off collapse and survive for a few years before their magnetic energy is sufficiently dissipated due to ambipolar diffusion. In addition, we speculate on multimessenger signatures of such objects and discuss the robustness of our results against limitations placed by neutron superfluidity and magnetothermal evolution.

LIGO and Virgo have initiated the era of gravitational-wave (GW) astronomy; but in order to fully explore GW frequency spectrum, we must turn our attention to innovative techniques for GW detection. One such approach is to use binary systems as dynamical GW detectors by studying the subtle perturbations to their orbits caused by impinging GWs. We present a powerful new formalism for calculating the orbital evolution of a generic binary coupled to a stochastic background of GWs, deriving from first principles a secularly-averaged Fokker-Planck equation which fully characterizes the statistical evolution of all six of the binary’s orbital elements. We also develop practical tools for numerically integrating this equation, and derive the necessary statistical formalism to search for GWs in observational data from binary pulsars and laser-ranging experiments.

There is a growing need for anomaly detection methods that can broaden the search for new particles in a model-agnostic manner. Most proposals for new methods focus exclusively on signal sensitivity. However, it is not enough to select anomalous events—there must also be a strategy to provide context to the selected events. We propose the first complete strategy for unsupervised detection of nonresonant anomalies that includes both signal sensitivity and a data-driven method for background estimation. Our technique is built out of two simultaneously trained autoencoders that are forced to be decorrelated from each other. This method can be deployed off-line for nonresonant anomaly detection and is also the first complete on-line-compatible anomaly detection strategy. We show that our method achieves excellent performance on a variety of signals prepared for the ADC2021 data challenge.

Liquid scintillator detectors play a central role in the detection of neutrinos from various sources. In particular, it is the only technique used so far for the precision spectroscopy of sub-MeV solar neutrinos, as demonstrated by the Borexino experiment at the Gran Sasso National Laboratory in Italy. The benefit of a high light yield, and thus a low energy threshold and a good energy resolution, comes at the cost of the directional information featured by water Cherenkov detectors, measuring ${}^8\mathrm{B}$ solar neutrinos above a few MeV. In this paper we provide the first directionality measurement of sub-MeV solar neutrinos which exploits the correlation between the first few detected photons in each event and the known position of the Sun for each event. This is also the first signature of directionality in neutrinos elastically scattering off electrons in a liquid scintillator target. This measurement exploits the subdominant, fast Cherenkov light emission that precedes the dominant yet slower scintillation light signal. Through this measurement, we have also been able to extract the rate of ${}^7\mathrm{Be}$ solar neutrinos in Borexino. The demonstration of directional sensitivity in a traditional liquid scintillator target paves the way for the possible exploitation of the Cherenkov light signal in future kton-scale experiments using liquid scintillator targets. Directionality is important for background suppression as well as the disentanglement of signals from various sources.

In this work we focus on computing the conformal dimensions $D(j_L,j_R)$ of local fields that transform in an irreducible representation of $SU(2)\times SU(2)$ labeled with $(j_L,j_R)$ at the $O(4)$ Wilson-Fisher fixed point using the Monte Carlo method. In the large charge expansion, among the sectors with a fixed large value of $j=\max (j_L,j_R)$, the leading sector has $|j_L-j_R|=0$ and the subleading one has $|j_L-j_R|=1$. Since Monte Carlo calculations at large $j$ become challenging in the traditional lattice formulation of the $O(4)$ model, a qubit regularized $O(4)$ lattice model was used recently to compute $D(j,j)$. Here we extend those calculations to the subleading sector. Our Monte Carlo results in the range $2\le j\le 20$ fit well to the expected large $j$ expansion $D(j,j-1)-D(j,j)\sim {\lambda }_0+{\lambda }_{1/2}/\sqrt{j}+{\lambda }_1/j+{\lambda }_{3/2}/j^{3/2}$, but we have to assume that at least one of the purely quantum mechanical contributions ${\lambda }_0$ or ${\lambda }_1$ is nonzero. Assuming ${\lambda }_0=0$ as conjectured recently, we find ${\lambda }_{1/2}\approx 2.1(1)$, ${\lambda }_1\approx 2.3(2)$, and ${\lambda }_{3/2}\approx 1.2(2)$.

We provide numerical evidence that the thermal QCD crossover turns into a first order transition in the presence of large enough magnetic background fields. The critical end point is found to be located between $eB=4{\mathrm{GeV}}^2$ [where the pseudocritical temperature is $T_c=(98\pm 3)\mathrm{MeV}$] and $eB=9{\mathrm{GeV}}^2$ [where the critical temperature is $T_c=(63\pm 5)\mathrm{MeV}$]. Results are based on the analysis of quark condensates and number susceptibilities, determined by lattice simulations of $N_f=2+1$ QCD at the physical point, discretized via rooted stout staggered fermions and a Symanzik tree level improved pure gauge action, adopting two different lattice spacings, $a=0.114$ and 0.086 fm, for $eB=9{\mathrm{GeV}}^2$ and three, $a=0.114$, 0.086, and 0.057 fm, for $eB=4{\mathrm{GeV}}^2$. We also present preliminary results regarding the confining properties of the thermal theory, suggesting that they could change drastically going across the phase transition.

We employ the recently improved description of dense baryonic matter within the Witten-Sakai-Sugimoto model to construct neutron stars. In contrast to previous holographic approaches, the presence of an isospin asymmetry allows us to implement beta equilibrium and electric charge neutrality. As a consequence, we are able to model the crust of the star within the same formalism and compute the location of the crust-core transition dynamically. After showing that a simple pointlike approximation for the baryons fails to satisfy astrophysical constraints, we demonstrate that our improved description does account for neutron stars that meet the current experimental constraints for mass, radius, and tidal deformability. However, we also point out tensions in the parameter fit and large-$N_c$ artifacts and discuss how to potentially resolve them in the future.

We derive supernova (SN) bounds on muon-philic bosons, taking advantage of the recent emergence of muonic SN models. Our main innovations are to consider scalars $\varphi$ in addition to pseudoscalars $a$ and to include systematically the generic two-photon coupling $G_{\gamma \gamma }$ implied by a muon triangle loop. This interaction allows for Primakoff scattering and radiative boson decays. The globular-cluster bound $G_{\gamma \gamma }<0.67\times {10}^{-10}{\mathrm{GeV}}^{-1}$ carries over to the muonic Yukawa couplings as $g_a<3.1\times {10}^{-9}$ and $g_{\varphi }<4.6\times {10}^{-9}$ for $m_{a,\varphi }\lesssim 100\mathrm{keV}$, so SN arguments become interesting mainly for larger masses. If bosons escape freely from the SN core the main constraints originate from SN 1987A $\gamma$ rays and the diffuse cosmic $\gamma$-ray background. The latter allows at most ${10}^{-4}$ of a typical total SN energy of $E_{\mathrm{SN}}\simeq 3\times {10}^{53}\mathrm{erg}$ to show up as $\gamma$ rays, for $m_{a,\varphi }\gtrsim 100\mathrm{keV}$ implying $g_a\lesssim 0.9\times {10}^{-10}$ and $g_{\varphi }\lesssim 0.4\times {10}^{-10}$. In the trapping regime the bosons emerge as quasi-thermal radiation from a region near the neutrino sphere and match $L_{\nu }$ for $g_{a,\varphi }\simeq {10}^{-4}$. However, the $2\gamma$ decay is so fast that all the energy is dumped into the surrounding progenitor-star matter, whereas at most ${10}^{-2}{E}_{\mathrm{SN}}$ may show up in the explosion. To suppress boson emission below this level we need yet larger couplings, $g_a\gtrsim 2\times {10}^{-3}$ and $g_{\varphi }\gtrsim 4\times {10}^{-3}$. Muonic scalars can explain the muon magnetic-moment anomaly for $g_{\varphi }\simeq 0.4\times {10}^{-3}$, a value hard to reconcile with SN physics despite the uncertainty of the explosion-energy bound. For generic axionlike particles, this argument covers the “cosmological triangle” in the $G_{a\gamma \gamma }–m_a$ parameter space.

In the preceding paper [A. A. Mironov, S. Meuren, and A. M. Fedotov, Phys. Rev. D 102, 053005 (2020)] we have demonstrated a feasible resummation of the bubble-chain corrections to the electron elastic scattering amplitude in a strong constant crossed electromagnetic field. Here we present a calculation of a more general contribution to the off-shell electron mass operator in a constant crossed field with an exact photon propagator in a loop. Using such an approximated mass operator, we also obtain a corrected electron propagator and elastic scattering amplitude. The results are expressed in the form of expansion over $\gamma$-matrix structures with scalar coefficients depending on the electron virtuality and the quantum dynamical parameter. By asymptotic analysis we identify the dominant contribution in the strong field limit. All the calculations were made by means of the original open-access computer-algebraic scripts. Our findings can be applied to a consistent study of the Dyson-Schwinger equations in strong-field QED.

We explore a new method to calculate the valence light-front wave function of a system of two interacting particles, which is based on contour deformations combined with analytic continuation methods to project the Bethe-Salpeter wave function onto the light front. In this proof-of-concept study, we solve the Bethe-Salpeter equation for a scalar model and find excellent agreement between the light-front wave functions obtained with contour deformations and those obtained with the Nakanishi method frequently employed in the literature. The contour-deformation method is also able to handle extensions of the scalar model that mimic certain features of QCD such as unequal masses and complex singularities. In principle the method is suitable for computing parton distributions on the light front such as parton distribution functions, transverse momentum distributions and generalized parton distributions in the future.

The appearance of a light composite $0^{+}$ scalar resonance in nearly conformal gauge-fermion theories motivates further study of the low energy structure of these theories. To this end, we present a nonperturbative lattice calculation of s-wave scattering of Goldstone bosons in the maximal-isospin channel in SU(3) gauge theory with $N_f=8$ light, degenerate flavors. The scattering phase shift is measured both for different values of the underlying fermion mass and for different values of the scattering momentum. We examine the effect of a light flavor-singlet scalar (reported in earlier studies) on Goldstone boson scattering, employing a dilaton effective field theory (EFT) at the tree level. The EFT gives a good description of the scattering data, insofar as the magnitude of deviations between EFT and lattice data are no larger than the expected size of next-to-leading order corrections in the EFT.

An improved measurement of the decay $B_s^0\to {\mu }^{+}{\mu }^{-}$ and searches for the decays $B^0\to {\mu }^{+}{\mu }^{-}$ and $B_s^0\to {\mu }^{+}{\mu }^{-}\gamma$ are performed at the LHCb experiment using data collected in proton-proton collisions at $\sqrt{s}=7$, 8 and 13 TeV, corresponding to integrated luminosities of 1, 2 and $6{\mathrm{fb}}^{-1}$, respectively. The $B_s^0\to {\mu }^{+}{\mu }^{-}$ branching fraction and effective lifetime are measured to be $\mathcal{B}(B_s^0\to {\mu }^{+}{\mu }^{-})=(3.09_{-0.43-0.11}^{+0.46+0.15})\times {10}^{-9}$ and $\tau (B_s^0\to {\mu }^{+}{\mu }^{-})=(2.07\pm 0.29\pm 0.03)\mathrm{ps}$, respectively, where the uncertainties include both statistical and systematic contributions. No significant signal for $B^0\to {\mu }^{+}{\mu }^{-}$ and $B_s^0\to {\mu }^{+}{\mu }^{-}\gamma$ decays is found and the upper limits $\mathcal{B}(B^0\to {\mu }^{+}{\mu }^{-})<2.6\times {10}^{-10}$ and $\mathcal{B}(B_s^0\to {\mu }^{+}{\mu }^{-}\gamma )<2.0\times {10}^{-9}$ at 95% confidence level are determined, where the latter is limited to the range $m_{\mu \mu }>4.9\mathrm{GeV}/c^2$. Additionally, the ratio between the $B^0\to {\mu }^{+}{\mu }^{-}$ and $B_s^0\to {\mu }^{+}{\mu }^{-}$ branching fractions is measured to be ${\mathcal{R}}_{{\mu }^{+}{\mu }^{-}}<0.095$ at 95% confidence level. The results are in agreement with the Standard Model predictions.