Recent studies of the cosmic-ray antiproton-to-proton ratio have identified an excess of $\sim 10–20\mathrm{GeV}$ antiprotons relative to the predictions of standard astrophysical models. Intriguingly, the properties of this excess are consistent with the same range of dark matter models that can account for the long-standing excess of $\gamma$-rays observed from the Galactic Center. Such dark matter candidates can also produce significant fluxes of antideuterium and antihelium nuclei. Here we study the production and transport of such particles, both from astrophysical processes as well as from dark matter annihilation. Importantly, in the case of AMS-02, we find that Alfvénic reacceleration (i.e., diffusion in momentum space) can boost the expected number of $\overline{\mathrm{d}}$ and ${}^3\overline{\mathrm{He}}$ events from annihilating dark matter by an order of magnitude or more. For relatively large values of the Alfvén speed, and for dark matter candidates that are capable of producing the antiproton and $\gamma$-ray excesses, we expect annihilations to produce a few antideuteron events and about one antihelium event in 6 yr of AMS-02 data. This is particularly interesting in light of recent reports from the AMS-02 Collaboration describing the detection of a number of antihelium candidate events.

Light axions ($m_a\lesssim {10}^{-10}\mathrm{eV}$) can form dense clouds around rapidly rotating astrophysical black holes via a mechanism known as rotational superradiance. The coupling between axions and photons induces a parametric resonance, arising from the stimulated decay of the axion cloud, which can rapidly convert regions of large axion number densities into an enormous flux of low-energy photons. In this work we consider the phenomenological implications of a superradiant axion cloud undergoing resonant decay. We show that the low-energy photons produced from such events will be absorbed over cosmologically short distances, potentially inducing massive shockwaves that heat and ionize the intergalactic medium over Mpc scales. These shockwaves may leave observable imprints in the form of anisotropic spectral distortions or inhomogeneous features in the optical depth.

Mounting evidence indicates that neutrinos likely undergo fast flavor conversion (FFC) in at least some core-collapse supernovae. Outcomes of FFC, however, remain highly uncertain. Here we study the cascade of flavor-field power from large angular scales in momentum space down to small ones, showing that FFC enhances this process and thereby hastens relaxation. Cascade also poses a computational challenge, which is present even if the flavor field is stable: When power reaches the smallest angular scale of the calculation, error from truncating the angular-moment expansion propagates back to larger scales, to disastrous effect on the overall evolution. Essentially the same issue has prompted extensive work in the context of plasma kinetics. This link suggests new approaches to averting spurious evolution, a problem that presently puts severe limitations on the feasibility of realistic oscillation calculations.

If ultralight bosonic fields exist in nature as dark matter, superradiance spins down rotating black holes (BHs), dynamically endowing them with equilibrium bosonic clouds, here dubbed synchronized gravitational atoms (SGAs). The self-gravity of these same fields, on the other hand, can lump them into (scalar or vector) horizonless solitons known as bosonic stars (BSs). We show that the dynamics of BSs yield a new channel forming SGAs. We study BS binaries that merge to form spinning BHs. After horizon formation, the BH spins up by accreting the bosonic field, but a remnant lingers around the horizon. If just enough angular momentum is present, the BH spin up stalls precisely as the remnant becomes a SGA. Different initial data lead to SGAs with different quantum numbers. Thus, SGAs may form both from superradiance-driven BH spin down and accretion-driven BH spin up. The latter process, moreover, can result in heavier SGAs than those obtained from the former: in one example herein, $\sim 18\%$ of the final system’s energy and $\sim 50\%$ of its angular momentum remain in the SGA. We suggest that even higher values may occur in systems wherein both accretion and superradiance contribute to the SGA formation.

The zeroth law of black hole mechanics is an assertion of constancy of the surface gravity on a stationary Killing horizon. The Hawking temperature of the black hole horizon is proportional to the surface gravity. Therefore, the constancy of the surface gravity is reminiscent of the zeroth law of ordinary thermodynamics. In this work, we provide a proof of the zeroth law in Lanczos-Lovelock theories of gravity, where the Einstein Hilbert action is supplemented by higher curvature terms.

We generalize a forward light-by-light scattering sum rule to the case of heavy quarkonium radiative transitions. We apply such a sum rule to the bottomonium states, and use available data on radiative transitions in its evaluation. For the transitions that are not known experimentally, we provide theoretical estimates within a potential model, and consider the spread between similar approaches in the literature as an estimate for the model error. For the $\mathrm{\Upsilon }(1S)$, $\mathrm{\Upsilon }(2S)$, and $\mathrm{\Upsilon }(3S)$ states we observe that, due to a cancellation between transitions involving ${\chi }_{b0},{\chi }_{b1}$, and ${\chi }_{b2}$ states, the sum rule is satisfied within experimental and theoretical error estimates. Having tested this sum rule for the low-lying bottomonium states, it may be used as a tool to investigate the nature of exotic states in the charmonium and bottomonium spectrum through the corresponding radiative transitions.

In this paper, we explore the evolution of baryon asymmetry as well as the hypermagnetic field in the early universe with an assumption that the flavon of the Froggatt-Nielsen carries an asymmetry. Through the decay of the flavon to Standard Model fermions, this asymmetry is transferred to fermions, where the right-handed electron keeps its asymmetry while its Yukawa interaction is out of thermal equilibrium. Through the existence of the flavon, we can ensure that the freezing-in temperature of the right-handed electron is closer to the electroweak phase transition than the Standard cosmology scenario. With this trick, the asymmetry in the right-handed electron is saved for a longer time. Moreover, the injection of the asymmetry to the right-handed electron is gradual, which helps the preservation of the asymmetry in the right-handed sector significantly. Due to the intimate relationship between fermion number violation and the helicity of the hypermagnetic field, some of the asymmetry is used to amplify the hypermagnetic field which itself helps to preserve the remnant asymmetry through keeping the Yukawa processes out of thermal equilibrium. We find the sweet region of the parameter space that can produce the right asymmetry in the baryons while generating a large hypermagnetic field by the time of the electroweak phase transition.

We propose a conceptual distinction between hard and soft realizations of deconfinement from nuclear to quark matter. In the high density region of hard deconfinement the repulsive hard cores of baryons overlap each other and bulk thermodynamics is dominated by the core properties that can be experimentally accessed in high-energy scattering experiments. We find that the equation of state estimated from a single baryon core is fairly consistent with those empirically known from neutron star phenomenology. We next discuss a novel concept of soft deconfinement, characterized by quantum percolation of quark wave functions, at densities lower than the threshold for hard deconfinement. We make a brief review of quantum percolation in the context of nuclear and quark matter and illustrate a possible scenario of quark deconfinement at high baryon densities.

We introduce a model in which the genesis of dark matter (DM) and neutrino masses is associated with a first-order phase transition of a scalar singlet field. During the phase transition a source right-handed neutrino (RHN) acquires a spacetime-dependent mass dynamically, a small fraction of which is converted via resonant oscillations into a very weakly mixed dark RHN which decays to a dark matter RHN with the observed relic abundance. Neutrino masses are generated via a traditional two RHN type-I seesaw between a fourth RHN and the source neutrino. The gravitational waves produced during the phase transition have a peak frequency that increases with the DM mass, and are detectable at future gravitational-wave interferometers for DM masses above $\sim 1\mathrm{MeV}$. Since the source RHNs are heavier than the electroweak scale, successful leptogenesis is also attainable.

Neutrinoless double beta decay ($0\nu \beta \beta$) is a crucial test for lepton number violation. Observation of this process would have fundamental implications for neutrino physics, theories beyond the Standard Model and cosmology. Focusing on so-called short-range operators of $0\nu \beta \beta$ and their potential interplay with the standard light Majorana neutrino exchange, we present the first complete calculation of the relevant nuclear matrix elements, performed within the interacting boson model (IBM-2). Furthermore, we calculate the relevant phase space factors using exact Dirac electron wave functions, taking into account the finite nuclear size and screening by the electron cloud. The obtained numerical results are presented together with up-to-date limits on the standard mass mechanism and effective $0\nu \beta \beta$ short-range operators in the interacting boson model framework. Finally, we interpret the limits in the particle physics scenarios incorporating heavy sterile neutrinos, left-right symmetry and $R$-parity violating supersymmetry.

One of the more important systematic effects affecting lattice computations of the hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon, $a_{\mu }^{\mathrm{HVP}}$, is the distortion due to a finite spatial volume. In order to reach subpercent precision, these effects need to be reliably estimated and corrected for, and one of the methods that has been employed for doing this is finite-volume chiral perturbation theory. In this paper, we argue that finite-volume corrections to $a_{\mu }^{\mathrm{HVP}}$ can, in principle, be calculated at any given order in chiral perturbation theory. More precisely, once all low-energy constants needed to define the effective field theory representation of $a_{\mu }^{\mathrm{HVP}}$ in infinite volume are known to a given order, also the finite-volume corrections can be predicted to that order in the chiral expansion.

We study the dependence of the electric conductivity on chemical potential in finite-density $SU(2)$ gauge theory with $N_f=2$ flavors of rooted staggered sea quarks, in combination with Wilson-Dirac and domain-wall valence quarks. The pion mass is reasonably small with $m_{\pi }/m_{\rho }\approx 0.4$. We concentrate in particular on the vicinity of the chiral crossover, where we find the low-frequency electric conductivity to be most sensitive to small changes in fermion density. Working in the low-density QCD-like regime with spontaneously broken chiral symmetry, we obtain an estimate of the first nontrivial coefficient $c(T)$ of the expansion of conductivity $\sigma (T,\mu )=\sigma (T,0)(1+c(T){(\mu /T)}^2+O({\mu }^4))$ in powers of $\mu$, which has rather weak temperature dependence and takes its maximal value $c(T)\approx 0.10\pm 0.07$ around the critical temperature. At larger densities and lower temperatures, the conductivity quickly grows toward the diquark condensation phase and also becomes closer to the free-quark result. As a by-product of our study we confirm the conclusions of previous studies with heavier pion that for $SU(2)$ gauge theory the ratio of crossover temperature to pion mass $T_c/m_{\pi }\approx 0.4$ at $\mu =0$ is significantly smaller than in real QCD.

The LHCb Collaboration has reported resonant activity in the channel $D^{+}{K}^{-}$, identifying two components: $X_0(2900)$ with $J^P=0^{+}$ at $2866\pm 7\mathrm{MeV}$, ${\mathrm{\Gamma }}_0=57\pm 13\mathrm{MeV}$ and $X_1(2900)$ with $J^P=1^{-}$ at $2904\pm 7\mathrm{MeV}$, ${\mathrm{\Gamma }}_1=110\pm 12\mathrm{MeV}$. We interpret the $X_0(2900)$ component as a $cs\overline{u}\overline{d}$ isosinglet compact tetraquark, calculating its mass to be $2863\pm 12\mathrm{MeV}$. This is the first exotic hadron with open heavy flavor. The analogous $bs\overline{u}\overline{d}$ tetraquark is predicted at $6213\pm 12\mathrm{MeV}$. We discuss possible interpretations of the heavier and wider $X_1(2900)$ state and examine potential implications for other systems with two heavy quarks.

In this work we consider the dilepton production via timelike Compton scattering (TCS) in electron-proton and proton-proton collisions. In particular, the differential cross section in terms of the dilepton invariant mass and rapidity is computed within the $k_T$-factorization approach. Besides, we utilize distinct unintegrated gluon distributions (UGD) in order to compare their impact on the differential cross section of TCS in $pp$ ($ep$) collisions evaluated at the LHC (LHeC), HL-LHC (LHeC), HE-LHC (LHeC), and FCC-hh (eh) center-of-mass energies.

We covariantize calculations over the manifold of phase space, establishing Stokes’ theorem for differential cross sections and providing new definitions of familiar observable properties like infrared and collinear safety. Through the introduction of explicit coordinates and a metric we show phase space is isomorphic to the product space of a simplex and a hypersphere, and we identify geometric phenomena that occur when its dimensions are large. These results have implications for fixed-order subtraction schemes, machine learning in particle physics and high-multiplicity heavy ion collisions.

The ratios of the $B_c{(2S)}^{+}$ to $B_c^{+}$, $B_c^{*}{(2S)}^{+}$ to $B_c^{+}$, and $B_c^{*}{(2S)}^{+}$ to $B_c{(2S)}^{+}$ production cross sections are measured in proton-proton collisions at $\sqrt{s}=13\mathrm{TeV}$, using a data sample collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of $143{\mathrm{fb}}^{-1}$. The three measurements are made in the $B_c^{+}$ meson phase space region defined by the transverse momentum $p_{\mathrm{T}}>15\mathrm{GeV}$ and absolute rapidity $|y|<2.4$, with the excited $B_c^{(*)}{(2S)}^{+}$ states reconstructed through the $B_c^{(*)+}{\pi }^{+}{\pi }^{-}$, followed by the $B_c^{+}\to J/\psi {\pi }^{+}$ and $J/\psi \to {\mu }^{+}{\mu }^{-}$ decays. The $B_c{(2S)}^{+}$ to $B_c^{+}$, $B_c^{*}{(2S)}^{+}$ to $B_c^{+}$, and $B_c^{*}{(2S)}^{+}$ to $B_c{(2S)}^{+}$ cross section ratios, including the unknown $B_c^{(*)}{(2S)}^{+}\to B_c^{(*)+}{\pi }^{+}{\pi }^{-}$ branching fractions, are $(3.47\pm 0.63(\mathrm{stat})\pm 0.33(\mathrm{syst}))\%$, $(4.69\pm 0.71(\mathrm{stat})\pm 0.56(\mathrm{syst}))\%$, and $1.35\pm 0.32(\mathrm{stat})\pm 0.09(\mathrm{syst})$, respectively. None of these ratios shows a significant dependence on the $p_{\mathrm{T}}$ or $|y|$ of the $B_c^{+}$ meson. The normalized dipion invariant mass distributions from the decays $B_c^{(*)}{(2S)}^{+}\to B_c^{(*)+}{\pi }^{+}{\pi }^{-}$ are also reported.

The decays ${\chi }_{cJ}\to {\mathrm{\Sigma }}^0\overline{p}{K}^{+}+\mathrm{c}.\mathrm{c}.$ $(J=0,1,2)$ are studied via the radiative transition $\psi (3686)\to \gamma {\chi }_{cJ}$ based on a data sample of $(448.1\pm 2.9)\times 10^6$ $\psi (3686)$ events collected with the BESIII detector. The branching fractions of ${\chi }_{cJ}\to {\mathrm{\Sigma }}^0\overline{p}{K}^{+}+\mathrm{c}.\mathrm{c}.$ $(J=0,1,2)$ are measured to be $(3.03\pm 0.12\pm 0.15)\times 10^{-4}$, $(1.46\pm 0.07\pm 0.07)\times 10^{-4}$, and $(0.91\pm 0.06\pm 0.05)\times 10^{-4}$, respectively, where the first uncertainties are statistical and the second are systematic. In addition, no evident structure is found for excited baryon resonances on the two-body subsystems with the limited statistics.

Exceptional field theories yield duality-covariant formulations of higher-dimensional supergravity. They have proven to be an efficient tool for the construction of consistent truncations around various background geometries. In this paper, we demonstrate how the formalism can moreover be turned into a powerful tool for computing the Kaluza-Klein mass spectra around these backgrounds. Most of these geometries have little to no remaining symmetries and their spectra are accessible to standard methods only in selected subsectors. The present formalism not only grants access to the full Kaluza-Klein spectra but also provides the scheme to identify the resulting mass eigenstates in higher dimensions. As a first illustration, we rederive in compact form the mass spectrum of IIB supergravity on $S^5$. We further discuss the application of our formalism to determine the mass spectra of higher Kaluza-Klein multiplets around the warped geometries corresponding to some prominent $\mathcal{N}=2$ and $\mathcal{N}=0$ AdS vacua in maximal supergravity.

Current studies of supersymmetric extensions of the Sachdev–Ye–Kitaev model stimulate a renewed interest in super-Schwarzian derivatives. In this work, we apply the method of nonlinear realizations to the finite-dimensional superconformal group $SU(1,1|2)$ and link its invariants to the $\mathcal{N}=4$ super-Schwarzian.

The closed, spatially isotropic Friedmann-Lemaître-Robertson-Walker universe ($k=+1$) is endowed with modifications due to a discrete underlying space-structure. Motivated from loop quantum gravity techniques, a full Thiemann regularization is performed. The impact of these modifications of the single-graph-sector appearing in the scalar constraint are interpreted as physical quantum gravity effects. We investigate the form of the modified scalar constraint and its analytical approximations for $k=+1$ spacetimes and assume this effective constraint as the generator of dynamics on the reduced isotropic phase space. It transpires that the system still features a classical recollapse with only marginal discreteness corrections. Moreover, the initial and final singularities are resolved and we present an effective model mirroring the qualitative features of system.