We present the first complete calculation of the soft photon self-energy to the next-to-leading order in a hot and/or dense ultrarelativistic plasma in QED. The calculation is performed within the real-time formalism utilizing dimensional regularization in $4-2ϵ$ dimensions, while the result is reported including explicit $O(ϵ)$ terms in the zero-temperature limit. This information is required to extend the perturbative calculation of the pressure of cold and dense QED matter to partial next-to-next-to-next-to-leading order in a weak-coupling expansion, reported in a companion paper. These results pave the way for a similar future calculation in quantum chromodynamics.

Gauge fields provide the fundamental interactions in the Standard Model of particle physics. Gauge field configurations with nontrivial topological windings are known to play crucial roles in many important phenomena, from matter-antimatter asymmetry of today’s universe to spontaneous chiral symmetry breaking in strong interaction. Their presence is, however, elusive for direct detection in experiments. Here we show that measurements of the chiral magnetic effect (CME) in heavy ion collisions can be used for accessing the topological fluctuations of the non-Abelian gauge fields in the quantum chromodynamics (QCD). To achieve this, we implemented a key ingredient, the stochastic dynamics of gauge field topological fluctuations, into a state-of-the-art framework for simulating the CME in these collisions. This new framework provides the necessary tool to quantify initial topological fluctuations from any definitive CME signal to be extracted from experimental data. It also reveals a universal scaling relation between initial topological fluctuations and particle multiplicity produced in the corresponding collision events.

Based on a data sample of $983{\mathrm{fb}}^{-1}$ collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider, we present the study of the heavy-flavor-conserving decay ${\mathrm{\Xi }}_c^0\to {\mathrm{\Lambda }}_c^{+}{\pi }^{-}$ with ${\mathrm{\Lambda }}_c^{+}$ reconstructed via its $p{K}^{-}{\pi }^{+}$ decay mode. The branching fraction ratio $\mathcal{B}({\mathrm{\Xi }}_c^0\to {\mathrm{\Lambda }}_c^{+}{\pi }^{-})/\mathcal{B}({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^{-}{\pi }^{+})$ is measured to be $0.38\pm 0.04\pm 0.04$. Combining with the world average value of $\mathcal{B}({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^{-}{\pi }^{+})$, the branching fraction $\mathcal{B}({\mathrm{\Xi }}_c^0\to {\mathrm{\Lambda }}_c^{+}{\pi }^{-})$ is deduced to be $(0.54\pm 0.05\pm 0.05\pm 0.12)\%$. Here, the uncertainties above are statistical, systematic, and from $\mathcal{B}({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^{-}{\pi }^{+})$, respectively.

We present a study of a singly Cabibbo-suppressed decay ${\mathrm{\Lambda }}_c^{+}\to p{K}_S^0{K}_S^0$ and a Cabibbo-favored decay ${\mathrm{\Lambda }}_c^{+}\to p{K}_S^0\eta$ based on $980{\mathrm{fb}}^{-1}$ of data collected by the Belle detector, operating at the KEKB energy-asymmetric $e^{+}{e}^{-}$ collider. We measure their branching fractions relative to ${\mathrm{\Lambda }}_c^{+}\to p{K}_S^0$: $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to p{K}_S^0{K}_S^0)/\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to p{K}_S^0)=(1.48\pm 0.08\pm 0.04)\times {10}^{-2}$ and $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to p{K}_S^0\eta )/\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to p{K}_S^0)=(2.73\pm 0.06\pm 0.13)\times {10}^{-1}$. Combining with the world average $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to p{K}_S^0)$, we have the absolute branching fractions, $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to p{K}_S^0{K}_S^0)=(2.35\pm 0.12\pm 0.07\pm 0.12)\times {10}^{-4}$ and $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to p{K}_S^0\eta )=(4.35\pm 0.10\pm 0.20\pm 0.22)\times {10}^{-3}$. The first and second uncertainties are statistical and systematic, respectively, while the third ones arise from the uncertainty on $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to p{K}_S^0)$. The mode ${\mathrm{\Lambda }}_c^{+}\to p{K}_S^0{K}_S^0$ is observed for the first time and has a statistical significance of $>10\sigma$. The branching fraction of ${\mathrm{\Lambda }}_c^{+}\to p{K}_S^0\eta$ has been measured with a threefold improvement in precision over previous results and is found to be consistent with the world average.

We discuss new possible tunneling processes in the presence of gravity. We formulate quantum tunneling using the Wheeler-deWitt canonical quantization and the WKB approximation. The distinctive feature of our formulation is that it accommodates the coexistence of Euclidean and Lorentzian evolution. It opens up a new possibility of quantum tunneling; e.g. a bubble wall itself tunnels the potential barrier pulling the field nearby, where the wall region experiences the Euclidean evolution while the other regions experience the Lorentzian evolution simultaneously. We execute numerical analysis and find that such a process can have a much higher tunneling rate than that of the Coleman-De Luccia bounce. We also find that the new tunneling processes exist even in the decoupling regime of gravity and affect low energy phenomenology.

We present a semiclassical analysis for Dirac fields on an arbitrary spacetime background and in the presence of a fixed electromagnetic field. Our approach is based on a Wentzel-Kramers-Brillouin approximation, and the results are analyzed at leading and next-to-leading order in the small expansion parameter $\hslash$. Taking into account the spin-orbit coupling between the internal and external degrees of freedom of wave packets, we derive effective ray equations with spin-dependent terms. These equations describe the gravitational spin Hall effect of localized Dirac wave packets. We treat both massive and massless Dirac fields and show how a covariantly defined Berry connection and the associated Berry curvature govern the semiclassical dynamics. The gravitational spin Hall equations are shown to be particular cases of the Mathisson-Papapetrou equations for spinning objects.

A key challenge for current and upcoming cosmic microwave background lensing measurements is their sensitivity to biases from extragalactic foregrounds, such as Sunyaev-Zel’dovich signals or cosmic infrared background emission. Several methods have been developed to mitigate these lensing foreground biases, dividing broadly into multifrequency cleaning approaches and modifications to the estimator geometry, but how to optimally combine these methods has not yet been explored in detail. In this paper, we examine which combination of lensing foreground mitigation strategies is best able to reduce the impact of foreground contamination for a Simons Observatory–like experiment while preserving maximal signal-to-noise. Although the optimal combination obtained depends on whether bias reduction or variance reduction is prioritized and on whether polarization data is used, generally, we find that combinations involving both geometric (profile hardening, source hardening, or shear) and multifrequency (symmetric cleaning) methods perform best. For lensing power spectrum measurements from temperature (polarization and temperature), our combined estimator methods are able to reduce the bias below $\sigma /4$ or 0.3% (0.1%), a factor of 16 (30) lower than the standard quadratic estimator bias, at a modest signal-to-noise cost of only 18% (12%). In contrast, single-method foreground-mitigation approaches struggle to reduce the bias to a negligible level below $\sigma /2$ without incurring a large noise penalty. For upcoming and current experiments, our combined methods therefore represent a promising approach for making lensing measurements with negligible foreground bias.

We constrain the distribution of merging compact binaries across the celestial sphere using the GWTC-3 catalog from the LIGO-Virgo-KAGRA Collaborations’ (LVK) third observing run. With 63 confident detections from O3, we constrain the relative variability (standard deviation) of the rate density across the sky to be $\lesssim 16\%$ at 90% confidence assuming the logarithm of the rate density is described by a Gaussian random field with correlation length $\ge 10°$. This tightens to $\lesssim 3.5\%$ when the correlation length is $\ge 20°$. While the new data provides the tightest constraints on anisotropies available to date, we do not find overwhelming evidence in favor of isotropy, either. A simple counting experiment favors an isotropic distribution by a factor of ${\mathcal{B}}_{\mathrm{ani}}^{\mathrm{iso}}=3.7$, which is nonetheless an improvement of more than a factor of two compared to analogous analyses based on only the LVK’s first and second observing runs.

We calculate the baryon-meson coupling constants for the spin-$1/2$ baryonic octet and spin-$3/2$ decuplet in a unified approach relying on symmetry arguments such as the fact that the Yukawa couplings, present in the Lagrangian density of the Walecka-type models, must be an invariant under SU(3) and SU(6) group transformations. The coupling constants of the baryon with the scalar $\sigma$ meson are fixed to reproduce the known potential depths for the hyperons and $\mathrm{\Delta }$ resonances, in an approach that can be extended to all particles. We then apply the calculated coupling constants to study neutron star matter with hyperons and deltas admixed to its composition. We conclude that the ${\mathrm{\Delta }}^{-}$ is by far the most important exotic particle that can be present in the neutron star interior. It is always present, independent of the chosen parametrization, and might appear in almost every known neutron star, once its onset happens at very low density. Yet, its presence affects the astrophysical properties of the canonical $1.4{\mathrm{M}}_{\odot }$ star, and, in some cases, it can even contribute to an increase in the maximum mass reached.

We present the nonperturbatively renormalized nucleon gluon momentum fraction using ensembles with $2+1+1$ flavors of highly improved staggered quarks (HISQ), generated by the MILC Collaboration. The calculation is done using clover fermions for the valence action with three pion masses, 220, 310, and 690 MeV, and three lattice spacings, 0.09, 0.12, and 0.15 fm. The renormalization is done using RI/MOM nonperturbative renormalization and using cluster-decomposition error reduction (CDER) to enhance the signal-to-noise ratio of the renormalization constant. We find the CDER technique is particularly important to improve the signal at the finer lattice ensembles where the lattice volume is larger. We extrapolate the gluon momentum fraction to the continuum-physical limit and obtain $⟨x{⟩}_g=0.502(53{)}_{\mathrm{stat}+\mathrm{NPR}}(50{)}_{\text{mixing}}$ in the $\overline{\mathrm{MS}}$ scheme at 2 GeV, where first error includes the statistical error and uncertainties in nonperturbative renormalization, while the latter systematic error accounts for ignoring quark mixing. Our gluon momentum fraction is consistent with other recent lattice-QCD results at physical pion mass.

In this work, we study the nonperturbative renormalization of the supercurrent operator in $\mathcal{N}=1$ supersymmetric Yang-Mills theory, using a gauge-invariant renormalization scheme (GIRS). The proposed prescription addresses successfully the unwanted mixing of the supercurrent with other operators of equal or lower dimension, which respect the same global symmetries. This mixing is introduced by the unavoidable breaking of supersymmetry on the lattice. In GIRS all gauge-noninvariant operators, which mix with the supercurrent, are excluded from the renormalization procedure. The one remaining mixing operator is accessible by numerical simulations. We present results for the renormalization of the supercurrent using GIRS. We also compute at one-loop order the conversion matrix which relates the nonperturbative renormalization factors in GIRS to the reference scheme $\overline{\mathrm{MS}}$.

We report a study of ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\pi }^0$, ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}\eta$, and ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\eta }^{\prime }$ using the data sample corresponding to an integrated luminosity of $980{\mathrm{fb}}^{-1}$ collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. The branching fractions relative to ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\pi }^0$ are measured as ${\mathcal{B}}_{{\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}\eta }/{\mathcal{B}}_{{\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\pi }^0}=0.25\pm 0.03\pm 0.01$ and ${\mathcal{B}}_{{\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\eta }^{\prime }}/{\mathcal{B}}_{{\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\pi }^0}=0.33\pm 0.06\pm 0.02$. Using ${\mathcal{B}}_{{\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\pi }^0}=(1.25\pm 0.10)\%$, we obtain ${\mathcal{B}}_{{\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}\eta }=(3.14\pm 0.35\pm 0.17\pm 0.25)\times {10}^{-3}$ and ${\mathcal{B}}_{{\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\eta }^{\prime }}=(4.16\pm 0.75\pm 0.25\pm 0.33)\times {10}^{-3}$. Here the uncertainties are statistical, systematic, and from ${\mathcal{B}}_{{\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\pi }^0}$, respectively. The ratio of the branching fraction of ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\eta }^{\prime }$ with respect to that of ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}\eta$ is measured to be ${\mathcal{B}}_{{\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\eta }^{\prime }}/{\mathcal{B}}_{{\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}\eta }=1.34\pm 0.28\pm 0.08$. We update the asymmetry parameter of ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\pi }^0$, ${\alpha }_{{\mathrm{\Sigma }}^{+}{\pi }^0}=-0.48\pm 0.02\pm 0.02$, with a considerably improved precision. The asymmetry parameters of ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}\eta$ and ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\eta }^{\prime }$ are measured to be ${\alpha }_{{\mathrm{\Sigma }}^{+}\eta }=-0.99\pm 0.03\pm 0.05$ and ${\alpha }_{{\mathrm{\Sigma }}^{+}{\eta }^{\prime }}=-0.46\pm 0.06\pm 0.03$ for the first time.

We exhibit the geometric structure of the convex cone in the linear space of the Wilson coefficients for the dimension-eight operators involving the left-handed lepton doublet $L$ and the Higgs doublet $H$ in the Standard Model effective field theory (SMEFT). The boundary of the convex cone gives rise to the positivity bounds on the Wilson coefficients, while the extremal ray corresponds to the unique particle state in the theory of ultraviolet completion. Among three types of canonical seesaw models for neutrino masses, we discover that only right-handed neutrinos in the type-I seesaw model show up as one of the extremal rays, whereas the heavy particles in the type-II and type-III seesaw models live inside the cone. The experimental determination of the relevant Wilson coefficients close to the extremal ray of the type-I seesaw model will unambiguously pin down or rule out the latter as the origin of neutrino masses. This discovery offers a novel way to distinguish the most popular seesaw model from others, and it also strengthens the SMEFT as an especially powerful tool to probe new physics beyond the Standard Model.

We analyze the general structure of the three-point functions involving conserved bosonic and fermionic higher-spin currents in three-dimensional conformal field theory. Using the constraints of conformal symmetry and conservation equations, we use a computational formalism to analyze the general structure of $⟨J_{s_1}{J}_{s_2}^{\prime }{J}_{s_3}^{\prime \prime }⟩$, where $J_{s_1}$, $J_{s_2}^{\prime }$, and $J_{s_3}^{\prime \prime }$ are conserved currents with spins $s_1$, $s_2$, and $s_3$ respectively (integer or half-integer). The calculations are completely automated for any chosen spins and are limited only by computer power. We find that the correlation function is in general fixed up to two independent “even” structures, and one “odd” structure, subject to a set of triangle inequalities. We also analyze the structure of three-point functions involving higher-spin currents and fundamental scalars and spinors.

String compactifications typically require fluxes, for example in order to stabilize moduli. Such fluxes, when they thread internal dimensions, are topological in nature and take on quantized values. This poses the puzzle as to how they could arise in the early universe, as they cannot be turned on incrementally. Working with string inspired models in six and eight dimensions, we show that there exist no-boundary solutions in which internal fluxes are present from the creation of the universe onwards. The no-boundary proposal can thus explain the origin of fluxes in a Kaluza-Klein context. In fact, it acts as a selection principle since no-boundary solutions are only found to exist when the fluxes have the right magnitude to lead to an effective potential that is positive and flat enough for accelerated expansion. Within the range of selected fluxes, the no-boundary wave function assigns higher probability to smaller values of flux. Our models illustrate how cosmology can act as a filter on a landscape of possible higher-dimensional solutions.

In this paper, we have studied the thermodynamics of Gauss-Bonnet black holes in $D$-dimensional anti–de Sitter (AdS) spacetime. Here, the cosmological constant ($\mathrm{\Lambda }$), Newton’s gravitational constant ($G$) and the Gauss-Bonnet parameter ($\alpha$) are varied in the bulk, and a mixed first law is rewritten considering central charge ($C$) (of dual boundary conformal theory) and its conjugate variable utilizing the gauge-gravity duality. A novel universal nature of central charge near the critical point of black hole phase transition in Einstein’s gravity has been observed in Cong et al. [Phys. Rev. Lett. 127, 091301 (2021)]. We observe that this universal nature breaks when such a phase transition is considered for black holes in the Gauss-Bonnet gravity. Apart from this, treating the Gauss-Bonnet parameter as a thermodynamic variable as suggested in Kastor et al. [Classical Quantum Gravity 27, 235014 (2010)] in light of the consistency between first law and the Smarr relation leads to modified thermodynamic volume (conjugate to variable cosmological constant), adding to a new understanding of the Van der Waals gas like behavior of the black holes in higher dimensional and higher curvature gravity theories. Our analysis considers a general $D$-dimensional background. We have then imposed a greater focus in the analysis of the phase structure of the five dimensional Gauss-Bonnet spacetime. Our analysis also shows that the general universal nature of the critical value of the central charge (which was present in four-dimensional AdS spacetime), breaks down in case of five-dimensional AdS spacetime even in the absence of Gauss-Bonnet gravity. This finding indicates the universal nature of the central charge may be a special feature of the four dimensional AdS spacetime only.

The potential breakdown of the notion of a metric at high energy scales could imply the existence of a fundamental minimal length scale below which distances cannot be resolved. One approach to realizing this minimum length scale is to construct a quantum field theory with a bandlimit on the field. We report on an investigation of the effects of imposing a bandlimit on a field on a curved and compact spacetime and how best to detect such a bandlimit if it exists. To achieve this operationally, we couple two Gaussian-smeared Unruh-DeWitt detectors to a scalar field on a $S^2\times R$ spherical spacetime through delta switching. The bandlimit is implemented through a cutoff of the allowable angular momentum modes of the field. We observe that a number of features of single detector response in the spherical case are similar to those in flat spacetime, including the dependence on the geometry of the detector, and that smaller detectors couple more strongly to the field, leading to an optimal size for bandlimit detection. We find that in flat spacetime squeezed detectors are more sensitive to the bandlimit provided they are larger than the optimal size; however, in spherical spacetime the bandlimit itself determines if squeezing improves the sensitivity. We also explore setups with two detectors, noting that in the spherical case, due to its compact nature, there is a lack of dissipation of any perturbation to the field, which results in locally excited signals being refocused at the poles. Quite strikingly, this feature can be exploited to significantly improve bandlimit detection via field mediated signaling. Moreover, we find that squeezing on a sphere introduces extra anisotropies that could be exploited to amplify or weaken the response of the second detector.

The renormalization of quantum field theories usually assumes Lorentz and gauge symmetries, besides the general restrictions imposed by unitarity and causality. However, the set of renormalizable theories can be enlarged by relaxing some of these assumptions. In this work, we consider the particular case of a $CPT$-preserving but Lorentz-breaking extension of scalar QED. For this theory, we calculate the one-loop radiative corrections to the three- and four-point scalar-vector vertex functions, at the lowest order in the Lorentz-violation parameters, and we explicitly verify that the resulting low-energy effective action is compatible with the usual gauge invariance requirements. With these results, we complete the one-loop renormalization of the model at the leading order in the Lorentz-violating parameters.

We reproduce and extend the previous studies of Lehner and Pretorius of the endpoint of the Gregory-Laflamme instability of black strings in five space-time dimensions. We consider unstable black strings of fixed thickness and different lengths, and in all cases we confirm that at the intermediate stages of the evolution the horizon can be interpreted as a quasistationary self-similar sequence of black strings connecting spherical black holes on different scales. However, we do not find any evidence for a global timescale relating subsequent generations. The endpoint of the instability is the pinch off of the horizon in finite asymptotic time, thus confirming the violation of the weak cosmic censorship conjecture around black string spacetimes.

The possible detection of echoes in late gravitational wave signals is the most promising way to test horizonless alternatives to general relativistic black holes, and probe the physics of these hypothetical ultracompact objects. While there is currently no evidence for the presence of such signatures, better accuracy is expected with the growing wealth of data from gravitational waves observatories. So far, several searches for these specific signals have been performed considering equidistant intervals between consecutive echoes, i.e. quasiperiodic waveforms, and ignoring possible backreaction effects of the incoming waves. Here we study scalar perturbations in exotic compact object scenarios that account for possible backreaction phenomena. In particular, we find that if one considers the increase of the central object mass due to the partial absorption of the energy carried by the perturbation, the echo signal can be quite different and nonperiodic. Apart from this simple scenario, we also consider the case in which, in order to preserve its compactness above the black hole limit, the compact object absorption shuts down in a finite amount of time or leads to an expansion. In both these cases we find interesting new features that should be taken into account in future searches.