The enhancement mechanism due to the resonant properties of the $\rho$ and $\omega$ mesons, which are close in mass, is analyzed when such resonances carry different momenta. Considerations from the particular process where they appear to the individual resonant features are at play for the appearance of the global resonant manifestation. In this work, we first consider the $e^{+}{e}^{-}\to {\pi }^0{\pi }^0\gamma$ process. We use the differential cross section at a given angle of emission of one of the pions, to tune the individual features of the two resonances and exhibit how both resonances combine to produce the enhancement. Then, we incorporate the ${\rho }^{\prime }$ using the information obtained from the $e^{+}{e}^{-}\to {\pi }^0{\pi }^0\gamma$ total scattering process and show that, it becomes important thanks to the same enhancement mechanism between the $\rho$ and the $\omega$. In a second step, we use a similar approach to describe a model dependent contribution to the ${\tau }^{-}\to {\pi }^{-}{\pi }^0{\nu }_{\tau }\gamma$ decay, the so-called $\omega$ channel. We show that the dipion invariant mass distribution at particular angles is sensitive to the individual resonant states. We compute the interference of this channel with the known dominant model independent contribution, and show how a better knowledge of the $e^{+}{e}^{-}\to {\pi }^0{\pi }^0\gamma$ process can help to properly account for such model dependent effects. The implication on the isospin symmetry breaking correction to tau-based estimates of the muon magnetic dipole moment is assessed.

Causality is necessary for retarded Green’s functions to remain retarded in all inertial frames in relativity, which ensures that dissipation of fluctuations is a Lorentz invariant concept. For first-order Bemfica, Disconzi, Noronha, and Kovtun theories with stochastic fluctuations, introduced via the Schwinger-Keldysh formalism, we show that imposing causality and stability leads to correlation functions of hydrodynamic fluctuations that only display the expected physical properties at small frequencies and wave number, i.e., within the expected regime of validity of the first-order approach. For second-order theories of the Israel and Stewart type, constructed using the information current such that entropy production is always non-negative, a stochastic formulation is presented using the Martin-Siggia-Rose approach where imposing causality and stability leads to correlators with the desired properties. We also show how Green’s functions can be determined from such an action. We identify a ${\mathbb{Z}}_2$ symmetry, analogous to the Kubo-Martin-Schwinger symmetry, under which this Martin-Siggia-Rose action is invariant. This modified Kubo-Martin-Schwinger symmetry provides a new guide for the effective action formulation of hydrodynamic systems with dynamics not solely governed by conservation laws. Furthermore, this symmetry ensures that the principle of detailed balance is valid in a covariant manner. We employ the new symmetry to further clarify the connection between the Schwinger-Keldysh and Martin-Siggia-Rose approaches, establishing a precise link between these descriptions in second-order theories of relativistic hydrodynamics. Finally, the modified Kubo-Martin-Schwinger symmetry is used to determine the corresponding action describing diffusion in Israel-Stewart theories in a general hydrodynamic frame.

The Bjorken sum rule and $R$ ratio are constructed to $O(a^4)$ in the Landau gauge in the three momentum subtraction schemes of Celmaster and Gonsalves where $a=g^2/(16{\pi }^2)$. We aim to examine the issue of convergence for observables in the various schemes as well as to test ideas on whether using the discrepancy in different scheme values is a viable and more quantum field theoretic alternative to current ways of estimating the theory error on a measurable.

Recently, Altmannshofer, Dror, and Gori (2022) claimed there is a four-point interaction, $W\text{−}\ell \text{−}\nu \text{−}a$, in the electroweak-violating scenario of axionlike particle (ALP) and lepton interactions which plays a critical role in searching for ALPs from ${\pi }^{\pm }$, $K^{\pm }$ mesons and $W$ boson decays because of the novel energy enhancements. Inspired by this interesting finding, we first propose new t-channel processes, $e^{+}{e}^{-}\to {\nu }_{e}a\overline{{\nu }_e}$ and $e^{-}p\to {\nu }_{e}aj$, for electrophilic ALPs ($e\mathrm{ALPs}$) which also involve $W\text{−}\ell \text{−}\nu \text{−}a$ four-point interaction and have obvious energy enhancement behaviors in their cross sections when the collision energy is increasing. On the other hand, heavier $e\mathrm{ALPs}$ mainly decay to a photon pair induced by the chiral anomaly instead of an electron-positron pair. Therefore, studies of these t-channel processes with a photon pair plus missing energy at $e^{+}{e}^{-}$ and $ep$ colliders open a new door to search for $e\mathrm{ALPs}$ at high energy colliders. The proposed search strategies are not only aiming to generate a larger production rate of $e\mathrm{ALPs}$, but also trying to distinguish electroweak-violating ALP-lepton interactions from electroweak-preserving ones.

We study the properties of hybrid stars containing a color superconducting quark matter phase in their cores, which is described by the chirally symmetric formulation of the confining relativistic density functional approach. It is shown that, depending on the dimensionless vector and diquark couplings of quark matter, the characteristics of the deconfinement phase transition are varied, allowing us to study the relation between those characteristics and mass-radius relations of hybrid stars. Moreover, we show that the quark matter equation of state (EoS) can be nicely fitted by the Alford-Braby-Paris-Reddy model that gives a simple functional dependence between the most important parameters of the EoS and microscopic parameters of the initial Lagrangian. Based on it, we analyze the special points of the mass-radius diagram in which several mass-radius curves intersect. Using the found empirical relation between the mass of the special point, the maximum mass of the mass-radius curve, and the onset mass of quark deconfinement, we constrain the range of values of the vector and diquark couplings of the quark matter model. With this constraint, we construct a family of mass-radius curves, which allow us to describe the black widow pulsar PSR J0952-0607 with a mass of $2.35\pm 0.17M_{\odot }$ as a hybrid star with a color superconducting quark matter core.

A remarkable exact mapping, valid for low-enough energy scales and close to a sharp boundary distribution of hadronic matter, from the ($3+1$)-dimensional Skyrme model to the sine-Gordon theory in ($1+1$) dimensions in the attractive regime is explicitly constructed. Besides the intrinsic theoretical interest to be able to describe the prototype of nonintegrable theories (namely, quantum chromodynamics in the infrared regime) in terms of the prototype of integrable relativistic field theories (namely, sine-Gordon theory in ($1+1$) dimensions), we will show that this mapping can be extremely useful to analyze both equilibrium and out-of-equilibrium features of baryonic distributions in a cavity.

We present the QCD corrections of order ${\alpha }_s^3$ to the decay rate of $b\to u\ell {\overline{\nu }}_{\ell }$, with $\ell =e$, $\mu$, originating from diagrams with closed fermion loops and neglecting the mass of the up quark. Our calculation relies on integration-by-parts reduction of Feynman integrals with one propagator raised to a symbolic power in kira and the numerical evaluation of master integrals with amflow. This allows us to obtain results for the fermionic contributions to the total semileptonic rate with an accuracy of more than 30 digits.

We study fishnet Feynman diagrams defined by a certain triangulation of a planar $n$-gon, with massless scalars propagating along and across the cuts. Our solution theory uses the technique of separation of variables, in combination with the theory of symmetric polynomials and Mellin space. The $n$-point split-ladders are solved by a recursion where all building blocks are made fully explicit. In particular, we find an elegant formula for the coefficient functions of the light-cone leading logs. When the diagram grows into a fishnet, we obtain new results exploiting a Cauchy identity decomposition of the measure over separated variables. This leads to an elementary proof of the Basso-Dixon formula at 4-points, while at $n$-points it provides a natural operator product expansion-like stratification of the diagram. Finally, we propose an independent approach based on “stampede” combinatorics to study the light-cone behavior of the diagrams as the partition function of a certain vertex model.

A new effective approach to the algebraic classification of geometries in $2+1$ gravity is presented. It uses five real Cotton scalars ${\mathrm{\Psi }}_{\mathrm{A}}$ of distinct boost weights, which are $3D$ analogs of the Newman-Penrose scalars representing the Weyl tensor in $4D$. The classification into types I, II, D, III, N, O is directly related to the multiplicity of the four Cotton-aligned null directions (CANDs). We derive a synoptic algorithm based on the invariants constructed from ${\mathrm{\Psi }}_{\mathrm{A}}$, and we show its agreement with the Petrov scheme based on eigenvalues and canonical Jordan form of the Cotton-York tensor. Our method is simpler and also general because it can be used in any $2+1$ theory, such as Einstein’s gravity or topologically massive gravity. As an example we analyze the algebraic structure of Robinson-Trautman spacetimes which include charged black holes with a cosmological constant.

Additional spin-0 particles appear in many extensions of the standard model. We search for long-lived spin-0 particles $S$ in $B$-meson decays mediated by a $b\to s$ quark transition in $e^{+}{e}^{-}$ collisions at the $\mathrm{\Upsilon }(4S)$ resonance at the Belle II experiment. Based on a sample corresponding to an integrated luminosity of $189{\mathrm{fb}}^{-1}$, we observe no evidence for signal. We set model-independent upper limits on the product of branching fractions $\mathcal{B}(B^0\to K^{*}(892{)}^0(\to K^{+}{\pi }^{-})S)\times \mathcal{B}(S\to x^{+}{x}^{-})$ and $\mathcal{B}(B^{+}\to K^{+}S)\times \mathcal{B}(S\to x^{+}{x}^{-})$, where $x^{+}{x}^{-}$ indicates $e^{+}{e}^{-},{\mu }^{+}{\mu }^{-},{\pi }^{+}{\pi }^{-}$, or $K^{+}{K}^{-}$, as functions of $S$ mass and lifetime at the level of ${10}^{-7}$.

A dedicated measurement of additional radiation in $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}\gamma$ and $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}\gamma$ initial-state-radiation events is presented using the full BABAR data sample. For the first time results are presented at next-to- and next-to-next-to-leading order, with one and two additional photons, respectively, for radiation from the initial and final states. Comparison with predictions from phokhara and afkqed Monte Carlo generators is performed, revealing discrepancies in the one-photon rates and angular distributions for the former. This disagreement has a negligible effect on the BABAR measurement of the $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}(\gamma )$ cross section, but could affect other measurements significantly. This study sheds a new light on the longstanding discrepancy in this channel that affects the theoretical prediction of hadronic vacuum polarization contributions to the muon magnetic moment anomaly.

We search for $CP$ violation by measuring a $T$-odd asymmetry in the Cabibbo-suppressed $D^{+}\to K^{+}{K}_S^0{\pi }^{+}{\pi }^{-}$ decay, and in the Cabibbo-favored $D_s^{+}\to K^{+}{K}_S^0{\pi }^{+}{\pi }^{-}$ and $D^{+}\to K^{+}{K}^{-}{K}_S^0{\pi }^{+}$ decays. We use $980{\mathrm{fb}}^{-1}$ of data collected by the Belle detector running at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. The $CP$-violating $T$-odd parameter $a_{CP}^{T\text{−}\mathrm{odd}}$ is measured to be $a_{CP}^{T\text{−}\mathrm{odd}}(D^{+}\to K^{+}{K}_S^0{\pi }^{+}{\pi }^{-})=(0.34\pm 0.87\pm 0.32)\%$, $a_{CP}^{T\text{−}\mathrm{odd}}(D_s^{+}\to K^{+}{K}_S^0{\pi }^{+}{\pi }^{-})=(-0.46\pm 0.63\pm 0.38)\%$, and $a_{CP}^{T\text{−}\mathrm{odd}}(D^{+}\to K^{+}{K}^{-}{K}_S^0{\pi }^{+})=(-3.34\pm 2.66\pm 0.35)\%$, where the first uncertainty is statistical and the second is systematic. We also report the first observation of the Cabibbo-suppressed decay $D_s^{+}\to K^{+}{K}^{-}{K}_S^0{\pi }^{+}$. The branching fraction is measured relative to that of the analogous Cabibbo-favored decay: $\mathcal{B}(D_s^{+}\to K^{+}{K}^{-}{K}_S^0{\pi }^{+})/\mathcal{B}(D_s^{+}\to K^{+}{K}_S^0{\pi }^{+}{\pi }^{-})=(1.36\pm 0.15\pm 0.04)\%$.

We reply to the “Comment” on “Regular evaporating black holes with stable cores” by R. Carballo-Rubio, F. Di Filippo, S. Liberati, C. Pacilio, and M. Visser. As a key result, we show that the regime of mass inflation identified in the comment connects smoothly to the late-time attractors discovered in our works [A. Bonanno et al., Regular black holes with stable cores, Phys. Rev. D 103, 124027 (2021) and Regular evaporating black holes with stable cores, Phys. Rev. D 107, 024005 (2023)]. Hence, the late-time stability of regular black holes is not affected by this intermediate phase.

Regular black holes are generically unstable because of the classical phenomenon that goes by the name of “mass inflation” which destabilizes the inner horizon. In a recent article, [A. Bonanno, A.-P. Khosravi, and F. Saueressig, Phys. Rev. D 107, 024005 (2023)], it is argued that semiclassical effects due to Hawking radiation can cure this instability, and some concerns are raised against the validity of previous analyses showing its existence in the first place. In this short comment, we explain our reservations regarding these recent claims, and reiterate the relevance of the mass inflation instability for regular black holes of astrophysical interest.

Double field theory (DFT) can be constructed as the double copy of a Yang-Mills theory. In this work we extend this statement by including higher-derivative terms. Starting from a four-derivative extension of Yang-Mills theory whose double copy is known to correspond to a conformal-gravity theory, we obtain a four-derivative theory formulated in double space, which in the pure gravity limit reduces to conformal gravity at quadratic order. This result reveals important aspects for the study of conformal symmetry in the context of DFT through double copy maps.

The exploration of scalar field theories that exhibit Carroll and Galilei symmetries has attracted a lot of attention. In this paper, we generalize these studies to fermionic field theories and construct consistent electric and magnetic descriptions of Carrollian and Galilean spin $\frac{1}{2}$ fermions. We showcase various methods that offer complementary perspectives into the limiting process of the underlying relativistic theories. Moreover, we extend our study to $\mathcal{N}=1$ off-shell supersymmetric field theories in four dimensions. By introducing suitable Grassmann-analyticity conditions, we formulate the corresponding super Carrollian and super-Galilean theories. These theories combine the established Carroll/Galilei scalars with the Carroll/Galilei fermions and a range of auxiliary fields into supermultiplets.

The problem of the possibility of observing a uniform sky glow through the throat of an Ellis-Bronnikov wormhole by an observer located in another asymptotically flat space-time is considered. It is shown that an individual star has multiple images, and the image of a luminous sky has a complex structure and contains ring structures. The reasons for the emergence of such structures are considered. The distribution of radiation intensity in the image along the radial coordinate is constructed. In addition, an image of the Ellis-Bronnikov wormhole is constructed against the background of uniform sky radiation in the observer’s space. A comparison to observations can be made by producing a synthetic Ellis-Bronnikov-type wormhole image against a CMB background. This image has been constructed by a combination of the images for inner and outer areas.

Constraining cosmological parameters from large-scale structure observations requires precise and accurate tools to compute its properties. While perturbation theory (PT) approaches can serve this purpose, exploration of large parameter space is challenging due to the potentially large computational cost of such calculations. In this study, we show that a response function approach applied to the regularized PT (RegPT) model at two-loop order, plus correction terms induced by redshift space distortion effects, can reduce the run-time by a factor of 50 compared to direct integration. We illustrate the performance of this approach by performing the parameter inference of five fundamental cosmological parameters from the redshift space power spectrum measured from $N$-body simulations as mock measurements, and inferred cosmological parameters are directly compared with parameters used to generate initial conditions of the simulations. From this PT challenge analysis, the constraining power of cosmological parameters and parameter biases are quantified with the survey volume and galaxy number density expected for the Euclid mission at the redshift $z=1$ as a function of the maximum wave number of data points $k_{\max }$. We find that RegPT with correction terms reproduces the input cosmological parameters without bias up to maximum wave number $k_{\max }=0.18h{\mathrm{Mpc}}^{-1}$. Moreover, $\text{RegPT}+$, which introduces one free parameter to RegPT to handle the damping feature on small scales, delivers the best performance among the examined models and achieves tighter constraints without significant parameter bias for higher maximum wave number $k_{\max }=0.21h{\mathrm{Mpc}}^{-1}$.

A characteristic observational signature of cosmic strings are short duration gravitational wave (GW) bursts. These have been searched for by the LIGO-Virgo-KAGRA (LVK) Collaboration and will be searched for with LISA. We point out that these burst signals are repeated, since cosmic string loops evolve quasiperiodically in time, and will always appear from essentially the same position in the sky. We estimate the number of GW repeaters for LVK and LISA and show that the string tension that can be probed scales as detector sensitivity to the sixth power, which raises hope for detection in future GW detectors. The observation of repeated GW bursts from the same cosmic string loop helps distinguish between the GW waveform parameters and the sky localization.

Ultralight dark matter (ULDM) halos constituted by ultralight axions (ULAs) generate gravitational potentials that oscillate in time. In this paper, I show these potentials interact with gravitational waves, resonantly amplifying them. For all ULA masses considered, the resonance in the solar region is currently negligible, while in a denser dark matter environment, which may arise in different scenarios, it might become significant. The frequency of the amplified gravitational wave is equal to the ULA mass in the case of the first resonance band, which represents the most efficient scenario.