We introduce the use of reinforcement-learning (RL) techniques to the conformal-bootstrap program. We demonstrate that suitable soft Actor-Critic RL algorithms can perform efficient, relatively cheap high-dimensional searches in the space of scaling dimensions and OPE-squared coefficients that produce sensible results for tens of CFT data from a single crossing equation. In this paper we test this approach in well-known 2D CFTs, with particular focus on the Ising and tricritical Ising models and the free compactified boson CFT. We present results of as high as 36-dimensional searches, whose sole input is the expected number of operators per spin in a truncation of the conformal-block decomposition of the crossing equations. Our study of 2D CFTs uses only the global $so(2,2)$ part of the conformal algebra, and our methods are equally applicable to higher-dimensional CFTs. When combined with other, already available, numerical and analytical methods, we expect our approach to yield an exciting new window into the nonperturbative structure of arbitrary (unitary or nonunitary) CFTs.

Muonium is a bound state composed of an antimuon and an electron, and it constitutes a hydrogenlike atom. Because of the absence of the hadronic matter in the bound state, the muonium is a useful probe to explore new physics being free from the hadronic uncertainties. The process of the muonium-to-antimuonium transition is considered to be effective to identify fundamental interactions which relate to the lepton flavor and lepton number violation. New experiments are being planned at J-PARC in Japan and CSNS in China, and it is expected to attract more attention in the near future. In this paper, we will study what kind of model can be verified in the next generation of the muonium-to-antimuonium transition search experiments while escaping the limitations from other experiments. Though the transition probability is strongly suppressed by the lepton flavor conservation in the standard model, it can be much larger by the exchanges of neutral and doubly charged bosons, and by box loop diagrams in new physics beyond the standard model. We study the neutrino models with heavy Majorana neutrinos at TeV scale, a type-II seesaw model, left-right models, and models for radiative neutrino masses such as the Zee-Babu model in particular, in addition to other possible models to induce the sizable transition probability, which can be tested in the forthcoming experiments.

We study how the evaporation of primordial black holes (PBHs) can affect the production of dark matter (DM) particles through thermal processes. We consider fermionic DM interacting with Standard Model particles via a spin-1 mediator in the context of a freeze-out or freeze-in mechanism. We show that when PBHs evaporate after dominating the Universe’s energy density, PBHs act as a source of DM and continuously inject entropy into the visible sector that can affect the thermal production in three qualitatively different ways. We compute the annihilation cross sections which account for the interactions between and within the PBH produced and thermally produced DM populations, and establish a set of Boltzmann equations which we solve to obtain the correct relic abundance in those different regimes and confront the results with a set of different cosmological constraints. We provide analytic formulas to calculate the relic abundance for the freeze-out and freeze-in mechanism in a PBH dominated early Universe. We identify regions of the parameter space where the PBHs dilute the relic density and thermalization occurs. Furthermore, we have made our code that numerically solves the Boltzmann equations publicly available.

Hawking evaporation of black holes in the early Universe is expected to copiously produce all kinds of particles, regardless of their charges under the Standard Model gauge group. For this reason, any fundamental particle, known or otherwise, could be produced during the black hole lifetime. This certainly includes dark matter (DM) particles. This paper improves upon previous calculations of DM production from primordial black holes (PBH) by consistently including the greybody factors, and by meticulously tracking a system of coupled Boltzmann equations. We show that the initial PBH densities required to produce the observed relic abundance depend strongly on the DM spin, varying in about $\sim 2$ orders of magnitude between a spin-2 and a scalar DM in the case of nonrotating PBHs. For Kerr PBHs, we have found that the expected enhancement in the production of bosons reduces the initial fraction needed to explain the measurements. We further consider indirect production of DM by assuming the existence of additional and unstable degrees of freedom emitted by the evaporation, which later decay into the DM. For a minimal setup where there is only one heavy particle, we find that the final relic abundance can be increased by at most a factor of $\sim 4$ for a scalar heavy state and a Schwarzschild PBH, or by a factor of $\sim 4.3$ for a spin-2 particle in the case of a Kerr PBH.

We present the first cosmology results from large-scale structure using the full $5000{\mathrm{deg}}^2$ of imaging data from the Dark Energy Survey (DES) Data Release 1. We perform an analysis of large-scale structure combining three two-point correlation functions ($3\times 2\mathrm{pt}$): (i) cosmic shear using 100 million source galaxies, (ii) galaxy clustering, and (iii) the cross-correlation of source galaxy shear with lens galaxy positions, galaxy–galaxy lensing. To achieve the cosmological precision enabled by these measurements has required updates to nearly every part of the analysis from DES Year 1, including the use of two independent galaxy clustering samples, modeling advances, and several novel improvements in the calibration of gravitational shear and photometric redshift inference. The analysis was performed under strict conditions to mitigate confirmation or observer bias; we describe specific changes made to the lens galaxy sample following unblinding of the results and tests of the robustness of our results to this decision. We model the data within the flat $\mathrm{\Lambda }\mathrm{CDM}$ and $w\mathrm{CDM}$ cosmological models, marginalizing over 25 nuisance parameters. We find consistent cosmological results between the three two-point correlation functions; their combination yields clustering amplitude $S_8=0.776_{-0.017}^{+0.017}$ and matter density ${\mathrm{\Omega }}_{\mathrm{m}}=0.339_{-0.031}^{+0.032}$ in $\mathrm{\Lambda }\mathrm{CDM}$, mean with 68% confidence limits; $S_8=0.775_{-0.024}^{+0.026}$, ${\mathrm{\Omega }}_{\mathrm{m}}=0.352_{-0.041}^{+0.035}$, and dark energy equation-of-state parameter $w=-0.98_{-0.20}^{+0.32}$ in $w\mathrm{CDM}$. These constraints correspond to an improvement in signal-to-noise of the DES Year 3 $3\times 2\mathrm{pt}$ data relative to DES Year 1 by a factor of 2.1, about 20% more than expected from the increase in observing area alone. This combination of DES data is consistent with the prediction of the model favored by the Planck 2018 cosmic microwave background (CMB) primary anisotropy data, which is quantified with a probability-to-exceed $p=0.13$–0.48. We find better agreement between DES $3\times 2\mathrm{pt}$ and Planck than in DES Y1, despite the significantly improved precision of both. When combining DES $3\times 2\mathrm{pt}$ data with available baryon acoustic oscillation, redshift-space distortion, and type Ia supernovae data, we find $p=0.34$. Combining all of these datasets with Planck CMB lensing yields joint parameter constraints of $S_8=0.812_{-0.008}^{+0.008}$, ${\mathrm{\Omega }}_{\mathrm{m}}=0.306_{-0.005}^{+0.004}$, $h=0.680_{-0.003}^{+0.004}$, and $\sum m_{\nu }<0.13\mathrm{eV}$ (95% C.L.) in $\mathrm{\Lambda }\mathrm{CDM}$; $S_8=0.812_{-0.008}^{+0.008}$, ${\mathrm{\Omega }}_{\mathrm{m}}=0.302_{-0.006}^{+0.006}$, $h=0.687_{-0.007}^{+0.006}$, and $w=-1.031_{-0.027}^{+0.030}$ in $w\mathrm{CDM}$.

We investigate, by numerical lattice simulations, the static quark-antiquark potential, the flux tube properties and the chiral condensate for $N_f=2+1$ QCD with physical quark masses in the presence of strong magnetic fields, going up to $eB=9{\mathrm{GeV}}^2$, with continuum extrapolated results. The string tension for quark-antiquark separations longitudinal to the magnetic field is suppressed by 1 order of magnitude at the largest explored magnetic field with respect to its value at zero magnetic background, but is still nonvanishing; in the transverse direction, instead, the string tension is enhanced but seems to reach a saturation at around 50% of its value at $B=0$. The flux tube shows a consistent suppression/enhancement of the overall amplitude, with mild modifications of its profile. Finally, we observe magnetic catalysis in the whole range of explored fields with a behavior compatible with a lowest Landau level approximation, in particular with a linear dependence of the chiral condensate on $B$ which is in agreement, within errors, with that already observed for $eB\sim 1{\mathrm{GeV}}^2$.

When analyzing the galaxy bispectrum measured from spectroscopic surveys, it is imperative to account for the effects of nonuniform survey geometry. Conventionally, this is done by convolving the theory model with the window function; however, the computational expense of this prohibits full exploration of the bispectrum likelihood. In this work, we provide a new class of estimators for the unwindowed bispectrum, a quantity that can be straightforwardly compared to theory. This builds upon the work of Philcox [Phys. Rev. D 103, 103504 (2021)] for the power spectrum and comprises two parts (both obtained from an Edgeworth expansion): a cubic estimator applied to the data and a Fisher matrix, which deconvolves the bispectrum components. In the limit of weak non-Gaussianity, the estimator is minimum variance; furthermore, we give an alternate form based on Feldman-Kaiser-Peacock weights that is close to optimal and easy to compute. As a demonstration, we measure the binned bispectrum monopole of a suite of simulations using both conventional estimators and our unwindowed equivalents. Computation times are comparable, except that the unwindowed approach requires a Fisher matrix, computable in an additional $\mathcal{O}(100)$ CPU hours. Our estimator may be straightforwardly extended to measure redshift-space distortions and the components of the bispectrum in arbitrary separable bases. The techniques of this work will allow the bispectrum to straightforwardly be included in the cosmological analysis of current and upcoming survey data.

Large-scale Fourier modes of the cosmic density field are of great value for learning about cosmology because of their well-understood relationship to fluctuations in the early universe. However, cosmic variance generally limits the statistical precision that can be achieved when constraining model parameters using these modes as measured in galaxy surveys, and moreover, these modes are sometimes inaccessible due to observational systematics or foregrounds. For some applications, both limitations can be circumvented by reconstructing large-scale modes using the correlations they induce between smaller-scale modes of an observed tracer (such as galaxy positions). In this paper, we further develop a formalism for this reconstruction, using a quadratic estimator similar to the one used for lensing of the cosmic microwave background. We incorporate nonlinearities from gravity, nonlinear biasing, and local-type primordial non-Gaussianity, and verify that the estimator gives the expected results when applied to $N$-body simulations. We then carry out forecasts for several upcoming surveys, demonstrating that, when reconstructed modes are included alongside directly observed tracer density modes, constraints on local primordial non-Gaussianity are generically tightened by tens of percents compared to standard single-tracer analyses. In certain cases, these improvements arise from cosmic variance cancellation, with reconstructed modes taking the place of modes of a separate tracer, thus enabling an effective “multitracer” approach with single-tracer observations.

The weak gravity conjecture is typically stated as a bound on the mass-to-charge ratio of a particle in the theory. Alternatively, it has been proposed that its natural formulation is in terms of the existence of a particle which is self-repulsive under all long-range forces. We propose a closely related, but distinct, formulation, which is that it should correspond to a particle with non-negative self-binding energy. This formulation is particularly interesting in anti–de Sitter space, because it has a simple conformal field theory (CFT) dual formulation: let $\mathrm{\Delta }(q)$ be the dimension of the lowest-dimension operator with charge $q$ under some global $U(1)$ symmetry, then $\mathrm{\Delta }(q)$ must be a convex function of $q$. This formulation avoids any reference to holographic dual forces or even to locality in spacetime, and so we make a wild leap, and conjecture that such convexity of the spectrum of charges holds for any (unitary) conformal field theory, not just those that have weakly coupled and weakly curved duals. This charge convexity conjecture, and its natural generalization to larger global symmetry groups, can be tested in various examples where anomalous dimensions can be computed, by perturbation theory, $1/N$ expansions and semiclassical methods. In all examples that we tested we find that the conjecture holds. We do not yet understand from the CFT point of view why this is true.

We undertake the task of studying the nonlinear dynamics of quantum gravity motivated alternatives to black holes that in the classical limit appear as ultracompact shells of matter. We develop a formalism that should be amenable to numerical solution in generic situations. For a concrete model, we focus on the spherically symmetric anti-de Sitter (AdS) black bubble—a shell of matter at the Buchdahl radius separating a Schwarzschild exterior from an AdS interior. We construct a numerical code to study the radial dynamics of and accretion onto AdS black bubbles, with exterior matter provided by scalar fields. In doing so, we develop numerical methods that could be extended to future studies beyond spherical symmetry. Regarding AdS black bubbles in particular, we find that the original prescription for the internal matter fluxes needed to stabilize the black bubble is inadequate in dynamical settings, and we propose a two-parameter generalization of the flux model to fix this. To allow for more efficient surveys of parameter space, we develop a simpler numerical model adapted to spherically symmetric bubble dynamics. We identify regions of parameter space that do allow for stable black bubbles and moreover allow control to a desired end state after an accretion episode. Based on these results, and evolution of scalar fields on black bubble backgrounds, we speculate on some observational consequences if what are currently presumed to be black holes in the Universe were actually black bubbles.

We formulate dissipative magnetohydrodynamic equations for finite-temperature superfluid and superconducting charged relativistic mixtures, taking into account the effects of particle diffusion and possible presence of Feynman-Onsager and/or Abrikosov vortices in the system. The equations depend on a number of phenomenological transport coefficients, which describe, in particular, relative motions of different particle species and their interaction with vortices. We demonstrate how to relate these transport coefficients to the mutual friction parameters and momentum transfer rates arising in the microscopic theory. The resulting equations can be used to study, in a unified and coherent way, a very wide range of phenomena associated with dynamical processes in neutron stars, e.g., the magnetothermal evolution, stellar oscillations and damping, as well as development and suppression of various hydrodynamic instabilities in neutron stars.

Fluctuations of conserved charges are sensitive to the QCD phase transition and a possible critical end point in the phase diagram at finite density. In this work, we compute the baryon number fluctuations up to tenth order at finite temperature and density. This is done in a QCD-assisted effective theory that accurately captures the quantum- and in-medium effects of QCD at low energies. A direct computation at finite density allows us to assess the applicability of expansions around vanishing density. By using different freeze-out scenarios in heavy-ion collisions, we translate these results into baryon number fluctuations as a function of collision energy. We show that a nonmonotonic energy dependence of baryon number fluctuations can arise in the noncritical crossover region of the phase diagram. Our results compare well with recent experimental measurements of the kurtosis and the sixth-order cumulant of the net-proton distribution from the STAR Collaboration. They indicate that the experimentally observed nonmonotonic energy dependence of fourth-order net-proton fluctuations is highly nontrivial. It could be an experimental signature of an increasingly sharp chiral crossover and may indicate a QCD critical point. The physics implications and necessary upgrades of our analysis are discussed in detail.

We determine approximate next-to-next-to-leading order (NNLO) corrections to unpolarized and polarized semi-inclusive deep-inelastic scattering. They are derived using the threshold resummation formalism, which we fully develop to next-to-next-to-leading logarithmic accuracy, including the two-loop hard factor. The approximate NNLO terms are obtained by expansion of the resummed expression. They include all terms in Mellin space that are logarithmically enhanced at threshold, or that are constant. In terms of the customary semi-inclusive deep-inelastic scattering variables $x$ and $z$ they include all double distributions (that is, “plus” distributions and $\delta$ functions) in the partonic variables. We also investigate corrections that are suppressed at threshold and we determine the dominant terms among these. Our numerical estimates suggest much significance of the approximate NNLO terms, along with a reduction in scale dependence.

The standard vacuum bounce formalism suffers from inconsistencies when applied to thermal bubble nucleation, for which ad hoc workarounds are commonly adopted. Identifying the length scales on which nucleation takes place, we demonstrate how the construction of an effective description for these scales naturally resolves the problems of the standard vacuum bounce formalism. Further, by utilising high-temperature dimensional reduction, we make a connection to classical nucleation theory. This offers a clear physical picture of thermal bubble nucleation, as well as a computational framework which can then be pushed to higher accuracy. We demonstrate the method for three qualitatively different quantum field theories.

We study the critical $O(3)$ model using the numerical conformal bootstrap. In particular, we use a recently developed cutting-surface algorithm to efficiently map out the allowed space of conformal field theory data from correlators involving the leading $O(3)$ singlet $s$, vector $\varphi$, and rank-2 symmetric tensor $t$. We determine their scaling dimensions to be $({\mathrm{\Delta }}_{\varphi },{\mathrm{\Delta }}_s,{\mathrm{\Delta }}_t)=(0.518942(51),1.59489(59),1.20954(23))$, and also bound various operator product expansion coefficients. We additionally introduce a new “tip-finding” algorithm to compute an upper bound on the leading rank-4 symmetric tensor $t_4$, which we find to be relevant with ${\mathrm{\Delta }}_{t_4}<2.99056$. The conformal bootstrap thus provides a numerical proof that systems described by the critical $O(3)$ model, such as classical Heisenberg ferromagnets at the Curie transition, are unstable to cubic anisotropy.

We extend the calculation of dark matter direct detection rates via electronic transitions in general dielectric crystal targets, combining state-of-the-art density functional theory calculations of electronic band structures and wave functions near the band gap, with semianalytic approximations to include additional states farther away from the band gap. We show, in particular, the importance of all-electron reconstruction for recovering large momentum components of electronic wave functions, which, together with the inclusion of additional states, has a significant impact on direct detection rates, especially for heavy mediator models and at $\mathcal{O}(10\mathrm{eV})$ and higher energy depositions. Applying our framework to silicon and germanium (that have been established already as sensitive dark matter detectors), we find that our extended calculations can appreciably change the detection prospects. Our calculational framework is implemented in an open-source program exceed-dm (Extended Calculation of Electronic Excitations for Direct detection of Dark Matter), to be released in an upcoming publication.

Stars that approach a supermassive black hole (SMBH) too closely can be disrupted by the tidal gravitational field of the SMBH. The resulting debris forms a tidal stream orbiting the SMBH, which can collide with itself due to relativistic apsidal precession. These self-collisions dissipate energy, causing the stream to circularize. We perform kinematic simulations of these stream self-collisions to estimate the efficiency of this circularization as a function of SMBH mass $M_{•}$ and penetration factor $\beta$, the ratio of the tidal radius to the pericenter distance. We uncover two distinct regimes depending on whether the time $t_c$ at which the most tightly bound debris circularizes is greater or less than the time $t_{\mathrm{fb}}$ at which the mass fallback rate peaks. The bolometric light curve of energy dissipated in the stream self-collisions has a single peak at $t>t_{\mathrm{fb}}$ in the slow circularization regime ($t_c>t_{\mathrm{fb}}$) but two peaks (one at $t<t_{\mathrm{fb}}$ and a second at $t_{\mathrm{fb}}$) in the fast circularization regime ($t_c<t_{\mathrm{fb}}$). Tidal streams will circularize in the slow (fast) regime for apsidal precession angles less (greater) than 0.2 radians, which occur for $\beta \lesssim (\gtrsim )(M_{•}/{10}^6{M}_{\odot }{)}^{-2/3}$. The observation of prominent double peaks in bolometric tidal disruption event light curves near the transition between these two regimes would strongly support our model of tidal-stream kinematics.

Does the value of the Higgs mass parameter affect the expectation value of local operators in the Standard Model? For essentially all local operators the answer to this question is “no”, and this is one of the avatars of the hierarchy problem: Nothing is “triggered” when the Higgs mass parameter crosses zero. In this article, we explore settings in which Higgs mass parameters can act as a “trigger” for some local operators ${\mathcal{O}}_T$. In the Standard Model, this happens for ${\mathcal{O}}_T=\mathrm{Tr}(G\tilde{G})$. We also introduce a “type-0” two Higgs doublet model, with a $Z_4$ symmetry, for which ${\mathcal{O}}_T=H_1{H}_2$ is triggered by the Higgs masses, demanding the existence of new Higgs states necessarily comparable to or lighter than the weak scale, with no wiggle room to decouple them whatsoever. Surprisingly, this model is not yet entirely excluded by collider searches, and will be incisively probed by the high-luminosity run of the LHC, as well as future Higgs factories. We also discuss a possibility for using this trigger to explain the origin of the weak scale, invoking a landscape of extremely light, weakly interacting scalars ${\varphi }_i$, with a coupling to ${\mathcal{O}}_T$ needed to make it possible to find vacua with small enough cosmological constant. The weak scale trigger links the tuning of the Higgs mass to that of the cosmological constant, while coherent oscillations of the ${\varphi }_i$ can constitute dark matter.

Black hole formation in a core-collapse supernova is expected to lead to a distinctive, abrupt drop in neutrino luminosity due to the engulfment of the main neutrino-producing regions as well as the strong gravitational redshift of those remaining neutrinos which do escape. Previous analyses of the shape of the cutoff have focused on specific trajectories or simplified models of bulk neutrino transport. In this article, we integrate over simple null geodesics to investigate potential effects on the cutoff profile of including all neutrino emission angles from a collapsing surface in the Schwarzschild metric, and from a contracting equatorial mass ring in the Kerr metric. We find that the nonradial geodesics contribute to a softening of the cutoff in both cases. In addition, extreme rotation introduces significant changes to the shape of the tail which may be observable in future neutrino detectors, or combinations of detectors.

We report a reanalysis of the reactor antineutrino energy spectra based on the new relative measurements of the ratio $R={{}^{e}S}_5/{{}^{e}S}_9$ between cumulative $\beta$ spectra from ${}^{235}\mathrm{U}$ and ${}^{239}\mathrm{Pu}$, performed at a research reactor in National Research Centre Kurchatov Institute (KI). A discrepancy with the $\beta$ spectra measured at Institut Laue-Langevin (ILL) was observed, indicating a steady excess of the ILL ratio by the factor of $1.054\pm 0.002$. We find a value of the ratio between inverse beta decay cross section per fission for ${}^{235}\mathrm{U}$ and ${}^{239}\mathrm{Pu}$: ${(}^5{\sigma }_f{/}^9{\sigma }_f{)}_{KI}=1.45\pm 0.03$, and then we reevaluate the converted antineutrino spectra for ${}^{235}\mathrm{U}$ and ${}^{238}\mathrm{U}$. We conclude that the new predictions are consistent with the results of Daya Bay and STEREO experiments.