Recognizing symmetries in data allows for significant boosts in neural network training, which is especially important where training data are limited. In many cases, however, the exact underlying symmetry is present only in an idealized dataset, and is broken in actual data, due to asymmetries in the detector, or varying response resolution as a function of particle momentum. Standard approaches, such as data augmentation or equivariant networks fail to represent the nature of the full, broken symmetry, effectively overconstraining the response of the neural network. We propose a learning model which balances the generality and asymptotic performance of unconstrained networks with the rapid learning of constrained networks. This is achieved through a dual-subnet structure, where one network is constrained by the symmetry and the other is not, along with a learned symmetry factor. In a simplified toy example that demonstrates violation of Lorentz invariance, our model learns as rapidly as symmetry constrained networks but escapes its performance limitations.

Calabi-Yau compactifications of the $E_8\times E_8$ heterotic string provide a promising route to recovering the four-dimensional particle physics described by the Standard Model. While the topology of the Calabi-Yau space determines the overall matter content in the low-energy effective field theory, further details of the compactification geometry are needed to calculate the normalized physical couplings and masses of elementary particles. In this work, we present numerical computations of physical Yukawa couplings in a number of heterotic models in the standard embedding and demonstrate the existence of natural hierarchies, a coveted feature in string model building.

We propose a new factorization pattern for tree-level Yang-Mills (YM) amplitudes, where they decompose into a sum of gluings of two lower-point amplitudes by setting specific two-point nonplanar Mandelstam variables within a rectangular configuration to zero. This approach manifests the hidden zeros of YM amplitudes recently identified. Furthermore, by setting specific Lorentz products involving polarization vectors to zero, the amplitudes further reduce to a sum of products of three currents. These novel factorizations provide a fresh perspective on the structure of YM amplitudes, potentially enhancing our understanding and calculation of these fundamental quantities.

Frequentist parameter inference using profile likelihoods has received increased attention in the cosmology literature recently since it can give important complementary information to Bayesian credible intervals. Here, we give a pedagogical review of frequentist parameter inference in cosmology and focus on when the graphical profile likelihood construction gives meaningful constraints, i.e. confidence intervals with correct coverage. This construction rests on the assumption of the asymptotic limit of a large data set such as in Wilks’ theorem. We assess the validity of this assumption in the context of three cosmological models with Planck 2018 Plik_lite data. While our tests for the $\mathrm{\Lambda }\mathrm{CDM}$ model indicate that the profile likelihood method gives correct coverage, $\mathrm{\Lambda }\mathrm{CDM}$ with the sum of neutrino masses as a free parameter appears consistent with a Gaussian near a boundary motivating the use of the boundary-corrected or Feldman-Cousins graphical method; for $w_0\mathrm{CDM}$ with the equation of state of dark energy, $w_0$, as a free parameter, we find indication of a violation of the assumptions. Finally, we compare frequentist and Bayesian constraints of these models. Our results motivate care when using the graphical profile likelihood method in cosmology.

In our galaxy, white dwarfs inevitably undergo scattering and capture processes with the interstellar diffuse dark matter. The captured dark matter forms a dark halo that eventually evaporates or annihilates. Theoretical pulsation modes and observations of pulsating white dwarfs provide predictions about their evolution. This motivates us to study the impact of sub-MeV interstellar dark matter on the cooling processes of white dwarfs. In this work, we consider the collisions between dark matter and relativistic degenerate electrons inside white dwarfs, numerically calculating the energy input and output results from scattering, capture, evaporation, and annihilation processes. Based on observational data from G117-B15, we conclude that the maximum cooling luminosity of the interstellar sub-MeV dark matter is approximately $\sim {10}^{22}\mathrm{erg}/\mathrm{s}$, which is insufficient to provide an effective cooling mechanism for white dwarfs. Finally, if future observations detect a pulsating white dwarf in the Galactic center, the potential sensitivity of this scenario could extend to the region ${10}^{-3}\mathrm{MeV}<m_{\chi }<10\mathrm{MeV}$ and $6.02\times {10}^{-38}{\mathrm{cm}}^2>{\sigma }_0\ge 1.5\times {10}^{-40}{\mathrm{cm}}^2$.

A search for ${\eta }_c(2S)\to p\overline{p}{K}^{+}{K}^{-}$, together with measurement of branching fractions of ${\chi }_{cJ(J=0,1,2)}\to p\overline{p}{K}^{+}{K}^{-}$ in the $\psi (3686)\to \gamma {\eta }_c(2S)$ and the $\psi (3686)\to \gamma {\chi }_{cJ}$ radiative decays, is performed with $(2712.4\pm 14.3)\times {10}^6\psi (3686)$ events collected with the BESIII detector at the BEPCII collider. An evidence for ${\eta }_c(2S)\to p\overline{p}{K}^{+}{K}^{-}$ is found, with a significance of $3.3\sigma$. The product branching fraction of $\mathcal{B}[\psi (3686)\to \gamma {\eta }_c(2S)]·\mathcal{B}[{\eta }_c(2S)\to p\overline{p}{K}^{+}{K}^{-}]$ is determined to be $(1.98\pm 0.41_{\mathrm{stat}}\pm 0.99_{\mathrm{syst}})\times {10}^{-7}$. The product branching fractions of $\mathcal{B}[\psi (3686)\to \gamma {\chi }_{cJ}]·\mathcal{B}[{\chi }_{cJ}\to p\overline{p}{K}^{+}{K}^{-}]$ are measured to be $(2.49\pm 0.03_{\mathrm{stat}}\pm 0.15_{\mathrm{syst}})\times {10}^{-5}$, $(1.83\pm 0.02_{\mathrm{stat}}\pm 0.11_{\mathrm{syst}})\times {10}^{-5}$, and $(2.43\pm 0.02_{\mathrm{stat}}\pm 0.15_{\mathrm{syst}})\times {10}^{-5}$, for $J=0$, 1, and 2, respectively.

We investigate the behavior of vector mesons $\rho$, $\varphi$, and $J/\mathrm{\Psi }$ in both nonrotating and rotating thermal media using the soft-wall holographic QCD model with four flavors. By incorporating anisotropic backgrounds derived from the Einstein-Maxwell-dilaton action, we incorporate rotational effects via a $U(1)$ gauge field, and the induced polarization of gluons is described by a rotation dependent dilation field. Spectral function analysis reveals that $\rho$ and $\varphi$ mesons exhibit broad peaks at lower temperatures, indicating their presence in the medium, while these peaks disappear at higher temperatures. Rotation delays this melting process, increasing the dissociation temperature. In contrast, the $J/\mathrm{\Psi }$ meson, owing to its heavy charm quark content, demonstrates its resilience to thermal effects. We further explore the global spin alignment of these mesons in the event plane frame. For the $\varphi$ meson, the averaged ${\rho }_{00}$ over the full range of azimuthal angles shows weak temperature dependence at low transverse momentum ($p_T$) but significant suppression at high $p_T$, aligning with experimental observations. Rotation enhances ${\rho }_{00}$ at high $p_T$, a phenomenon attributed to angular momentum transfer via spin-orbit coupling. The $J/\mathrm{\Psi }$ meson, however, displays insensitivity to temperature and rotation up to $p_T=5\mathrm{GeV}$, with a very small suppression observed at higher $p_T$, likely due to its heavy quark nature. Although $\rho$ meson spin alignment is not yet experimentally measured, it exhibits behavior qualitatively similar to the $\varphi$ meson, with thermal fluctuations dampening alignment and rotation enhancing it.

In [B. Taghavi et al.Classical Liouville action and uniformization of orbifold Riemann surfaces, Phys. Rev. D 110, 046018 (2024)], two of the authors studied the function ${𝒮}_{\mathit{m}}=S_{\mathit{m}}-\pi {\sum }_{i=1}^n(m_i-\frac{1}{m_i})\log {\mathsf{h}}_i$ for orbifold Riemann surfaces of signature $(g;m_1,\dots ,m_{n_e};n_p)$ on the generalized Schottky space ${\mathfrak{S}}_{g,n}(\mathit{m})$. In this paper, we prove the holographic duality between ${𝒮}_{\mathit{m}}$ and the renormalized hyperbolic volume $V_{\mathrm{ren}}$ of the corresponding Schottky 3-orbifolds with lines of conical singularity that reach the conformal boundary. In case of the classical Liouville action on ${\mathfrak{S}}_g$ and ${\mathfrak{S}}_{g,n}(\mathbf{\infty })$, the holography principle was proved in [K. Krasnov, Holography and Riemann surfaces, Adv. Theor. Math. Phys. 4, 929 (2000).], [J. Park et al., Potentials and Chern forms for Weil–Petersson and Takhtajan–Zograf metrics on moduli spaces, Adv. Math. 305, 856 (2017).], respectively. Our result implies that $V_{\mathrm{ren}}$ acts as a Kähler potential for a particular combination of the Weil-Petersson and Takhtajan-Zograf metrics that appears in the local index theorem for orbifold Riemann surfaces, as discussed by [L. A. Takhtajan and P. Zograf, Local index theorem for orbifold Riemann surfaces, Lett. Math. Phys. 109, 1119 (2019).]. Moreover, we demonstrate that under the conformal transformations, the change of function ${𝒮}_{\mathit{m}}$ is equivalent to the Polyakov anomaly, which indicates that the function ${𝒮}_{\mathit{m}}$ is a consistent height function with a unique hyperbolic solution. Consequently, the associated renormalized hyperbolic volume $V_{\mathrm{ren}}$ also admits a Polyakov anomaly formula. The method we used to establish this equivalence may provide an alternative approach to derive the renormalized Polyakov anomaly for Riemann surfaces with punctures (cusps), as described by [P. Albin et al., Ricci flow and the determinant of the Laplacian on non-compact surfaces, Commun. Partial Diff. Eqn. 38, 711 (2013).].

We investigate the large-$N$ limit of the Berenstein-Maldacena-Nastase (BMN) matrix model with classical bosonic membranes which have spherical topologies and spin inside the 11-dimensional maximally supersymmetric plane-wave background. First we classify all possible M2-brane configurations based on the distribution of their components inside the $SO(3)\times SO(6)$ symmetric plane-wave spacetime. We then formulate a number of simple but very representative Ansätze of dielectric tops that rotate in this space. We examine the leading-order radial and angular/multipole stability for a wide range of these configurations. By analyzing perturbations at the next-to-leading order, we find that they exhibit the phenomenon of turbulent cascading of instabilities. Thereby, long-wavelength perturbations generate higher-order multipole instabilities through their nonlinear couplings.

We give the full representation theory of the gravitational extended corner symmetry group in two dimensions. This includes projective representations, which correspond to representations of the quantum corner symmetry group. We find that they are described by one-dimensional conformal fields with an additional index in the Fock space of the harmonic oscillator. We begin with a review of Mackey’s theory of induced representations and then proceed to its application to the corner symmetries. The field representations, induced from the irreducible representations of the special linear group, are worked out first. The little group method is then applied to the extended corner symmetry group to obtain the irreducible unitary representations. Finally, we focus on projective representations and their application to the description of local subsystems.

We study a landscape of four-dimensional $\mathcal{N}=1$ superconformal field theories (SCFTs) with identical central charges. These theories are obtained by renormalization group flows triggered by supersymmetry-preserving superpotential deformations of the $\mathcal{N}=1$ gauging of the flavor symmetry of a collection of $\mathcal{N}=2$ ${\mathcal{D}}_p(G)$ Argyres-Douglas SCFTs. In this work, we focus on the fixed points in the landscape of the $SU(3)$ gauging of three copies of the ${\mathcal{D}}_2(SU(3))=H_2$ theory together with an adjoint-valued chiral multiplet. We catalog the network of $a=c$ fixed points, and, along the way, we find a variety of dualities and instances of supersymmetry enhancement.

We study the Hagedorn temperature $T_H$ of strongly coupled quantum field theories admitting a holographic string or M-theory description in various regimes and scenarios. In the first part of the paper we propose a “thermal scalar” effective approach to the calculation of $T_H$ in eleven-dimensional supergravity. The proposal allows us to extend the existing results for $T_H$ to the strongly coupled string regime, i.e. to a previously unexplored regime of field theory parameters where the number of colors $N$ is smaller than (some power of) the ’t Hooft coupling $\lambda$. We can thus extend the existing results for the ${\alpha }^{\prime }$ expansion of the Aharony-Bergman-Jafferis-Maldacena model, which have a spectacular agreement with predictions from integrability, in a different direction in parameter space. In particular, we explicate the first nonperturbative corrections. We also apply the formalism to the Witten-Yang-Mills model, finding that the result for the ratio of $T_H$ with the deconfinement temperature is in the same ballpark of the lattice one for pure Yang-Mills. Within the same model, we study the dependence of the Hagedorn temperature on the $\theta$-angle. In the second part of the paper we analyze the effect of dynamical flavors on $T_H$ in confining theories. By studying the few available examples of regular backgrounds dual to confining theories with flavors, we find that generally the effects of flavors is to reduce the value of $T_H$ in units of the square root of the confining string tension. The effect turns out to be milder than the analogous reduction of the critical temperature for deconfinement when the latter is known.

Using the 2PI effective action formalism, we study false vacuum decay beyond the quadratic approximation of the path integral. We derive a coupled system of equations for the bounce and the propagator, and we compute a semianalytic expression for the self-energy of a real scalar field with cubic and quartic interactions from the 2PI effective action truncated at two loops and without further approximations. Deriving numerical results, we can show that the Hartree approximation, where nonlocal contributions to the self-energy are neglected, is generally not justified. The procedure we develop is a key step towards the explicit computation of the quantum corrected bounce, the determinant of fluctuations about it, and the decay rate in the presence of classical zero modes that are lifted by quantum effects, e.g., classically scale-invariant models relevant for assessing the Higgs stability.

We investigate a class of quantum field theories with relativistic Luttinger fermions and local self-interaction in scalar channels. For an understanding of possible low-energy phases, we first classify the set of mass terms arising from scalar fermion bilinears. For large flavor numbers, we show that each of our models features a coupling branch in which the theory is asymptotically free. In order to address the long-range behavior, we use mean-field theory which is exact in the limit of large flavor numbers. We identify two models which undergo dimensional transmutation, interconnecting the asymptotically free high-energy regime with an ordered low-energy phase sustaining a vacuum condensate. We also study the analytic structure of the Luttinger-fermionic propagator in the various possible gapped phases.

A generalization of the Majumdar-Papapetrou multi-black-hole spacetime was recently constructed by Teo and Wan [Phys. Rev. D 109, 044054 (2024)], describing charged and spinning (extremal) balanced black holes in asymptotically flat spacetime. We explore the dynamics of null geodesics on this geometry, focusing on the two-center solution. Using the topological charge formalism, we show that various light ring arrangements arise from different choices of individual angular momenta: light rings with opposite topological charges can merge and annihilate each other, resulting in configurations with a total of 4, 6, or 8 light rings. Using backward ray tracing, we obtained the shadow and lensing of these spacetimes. The former, in particular, closely resembles those for the double Kerr metric.

We study the number of propagating degrees of freedom, at nonlinear order, in torsion gravity theories, a class of modified theories of gravity that include a propagating torsion in addition to the metric. We focus on a three-parameter subfamily of theories (“torsion bigravity”) that contains, at linear order, only two physical excitations: a massless spin-2 one (with 2 degrees of freedom) and a massive spin-2 one (with 5 degrees of freedom). We study the dynamics of the massive spin-2 field in the limit where the torsion field decouples from the metric. The number of degrees of freedom of the torsion field is found to change, at nonlinear order, from five to nine.

Observations of the 21-cm signal are opening a window to the cosmic-dawn epoch when the first stars formed. These observations are usually interpreted with seminumerical or hydrodynamical simulations, which are often computationally intensive and inflexible to changes in cosmological or astrophysical effects. Here, we present an effective, fully analytic model for the impact of the first stars on the 21-cm signal, using the modular code zeus21. zeus21 employs an analytic prescription of the star formation rate density (SFRD) to recover the fully nonlinear and nonlocal correlations of radiative fields that determine the 21-cm signal. We introduce the earliest population stars residing in low-mass molecular-cooling galaxies in zeus21, with distinct spectra from later population II stars. We also self-consistently model feedback in the form of $H_2$-dissociating Lyman-Werner (LW) radiation as well as dark matter-baryon relative velocities, both of which suppress star formation in the lowest-mass halos. LW feedback produces a scale dependence on the SFRD fluctuations, due to the long mean free path of LW photons. Relative velocities give rise to “wiggles” in the spatial distribution of the 21-cm signal; we present an improved calculation of the shape of these velocity-induced acoustic oscillations, showing they remain a standard ruler at cosmic dawn. Our improved version of zeus21 predicts the 21-cm global signal and power spectra in agreement with simulations at the $\sim 10\%$ level, yet is at least 3 orders of magnitude faster. This public code represents a step toward efficient and flexible parameter inference at cosmic dawn, allowing us to predict the first billion years of the Universe in mere seconds.

We investigate the emission of vector radiation by superconducting cosmic string loops, deriving general relations to characterize the vector radiation emission efficiency, and study its impact on the evolution of loops. Building on these results, we compute the stochastic gravitational wave background generated by a chiral superconducting cosmic string network, including the impact of vector radiation for the very first time. Our analysis reveals that strong coupling between superconducting cosmic strings and the vector field may lead to a substantial suppression of the gravitational wave signal, while moderate coupling may still produce a detectable signal. We demonstrate that, in this intermediate limit, the presence of superconductivity in cosmic strings may help reconcile their gravitational wave spectrum with pulsar timing array data for large enough values of current.

We conduct a systematic investigation of freeze-in during reheating while taking care to include both direct and indirect production of dark matter (DM) via gravitational portals and inflaton decay. Direct production of DM can occur via gravitational scattering of the inflaton, while indirect production occurs through scattering in the Standard Model radiation bath. We consider two main contributions to the radiation bath during reheating. The first, which may dominate at the onset of the reheating process, is produced via gravitational scattering of the inflaton. The second (and more standard contribution) comes from inflaton decay. We consider a broad class of DM production rates parametrized as $R_{\chi }\propto T^{n+6}/{\mathrm{\Lambda }}^{n+2}$, and inflaton potentials with a power-law form $V(\varphi )\propto {\varphi }^k$ about the minimum. We find the relic density produced by freeze-in for each contribution to the Standard Model bath for arbitrary $k$ and $n$, and compare these with the DM density produced gravitationally by inflaton scattering. We find that freeze-in production from the gravitationally produced radiation bath can exceed that of the conventional decay bath and account for the observed relic density provided that $m_{\chi }>T_{\mathrm{RH}}$, with additional $k$- and $n$-dependent constraints. For each freeze-in interaction considered, we also find $m_{\chi }$- and $T_{\mathrm{RH}}$-dependent limits on the beyond the Standard Model scale, $\mathrm{\Lambda }$, for which gravitational production will exceed ordinary freeze-in production.