Recently Dolgov and Pozdnyakov proposed a new baryogenesis mechanism in which baryon asymmetry is produced without violating baryon number at the Lagrangian level. In this scenario, baryon asymmetry is generated by absorption of a new particle $X$ carrying baryon number onto primordial black holes (PBHs). Assuming $CP$-violation, the particle $X$ is absorbed at a different rate than the antiparticle $\overline{X}$, producing an asymmetry in the baryonic number. We independently test this scenario, finding that it suffers from two fundamental issues. At the phenomenological level, strong absorption by PBHs initially increases the baryon asymmetry. However, at later times such asymmetry is completely absorbed by PBHs. In order to overcome this issue, we account for PBH evaporation, which provides a natural way of halting the absorption while keeping a finite baryon asymmetry. We provide a systematic study of the parameter space, identifying the regions leading to the production of the baryon asymmetry without violating the known constraints on PBHs concentration. At the theoretical level, a model realizing the $CP$-violation postulated in this scenario is difficult to realize. We show, by implementing a minimal model, that the framework proposed in the original work in order to produce $CP$-violation, even if qualitatively correct, is quantitatively in disagreement with the observed baryon asymmetry, namely this mechanism produces only a fraction of the total baryon asymmetry.

The next decade is expected to see the launch of one or more space-based gravitational wave detectors: the European-led Laser Interferometer Space Antenna (LISA), and one or more Chinese mission concepts, Taiji and TianQin. One of the primary scientific targets for these missions is the merger of black holes with masses between ${10}^3{M}_{\odot }$ and ${10}^8{M}_{\odot }$. These systems may produce detectable electromagnetic signatures in addition to gravitational waves due to the presence of gas in minidisks around each black hole, and a circumbinary disk surrounding the system. The electromagnetic emission may occur before, during, and after the merger. In order to have the best chance of capturing all phases of the emission, it is imperative that the gravitational wave signals be detected at low latency and used to produce reliable estimates for the sky location and distance to help guide the search for counterparts. Low latency detection also provides a starting point for the “global fit” of the myriad signals that are simultaneously present in the data. Here, a low latency analysis pipeline is presented that is capable of analyzing months of data in just a few hours using a laptop from the last decade. The problem of performing a global fit is avoided by whitening out the bright foreground produced by nearby galactic binaries. The performance of the pipeline is illustrated using simulated data from the LISA Data Challenge.

We study quasinormal modes related to gravitational and electromagnetic perturbations of spherically symmetric charged black holes in nonlinear electrodynamics. Beyond the linear Maxwell electrodynamics, we consider a class of Lagrangian with higher-order corrections written by the electromagnetic field strength and its Hodge dual with arbitrary coefficients, and we parametrize the corrections for quasinormal frequencies in terms of the coefficients. It is confirmed that the isospectrality of quasinormal modes under parity is generally violated due to nonlinear electrodynamics. As applications, the corrections for quasinormal frequencies in Euler-Heisenberg and Born-Infeld electrodynamics are calculated, then it is clarified that the nonlinear effects act to lengthen the oscillation period and enhance the damping rate of the quasinormal modes.

We describe the design of a gravitational wave timing array, a novel scheme that can be used to search for low-frequency gravitational waves by monitoring continuous gravitational waves at higher frequencies. We show that observations of gravitational waves produced by Galactic binaries using a space-based detector like LISA provide sensitivity in the nanohertz to microhertz band. While the expected sensitivity is several magnitudes worse than what can be achieved by pulsar timing arrays, it supplements other recent proposals for gravitational wave searches in the microhertz regime. This regime is below the frequencies to which LISA is directly sensitive, and above the frequency range generally targeted by pulsar timing array searches. The low-frequency extension of sensitivity does not require any experimental design change to space-based gravitational wave detectors, and can be achieved with the data products that would already be collected by them.

We study the Kerr-Schild-Kundt class of metrics in generic gravity theories with Maxwell’s field. We prove that these metrics linearize and simplify the field equations of generic gravity theories with Maxwell’s field.

We study the superposition of primordial massive particles and compute the associated decoherence time scale in the radiation dominated Universe. We observe that for lighter primordial particles with masses up to ${10}^7\mathrm{kg}$, the corresponding decoherence timescale is significantly larger than the age of the observable Universe, demonstrating that a primordial particle would persist in a pure quantum state, with its wave function spreading freely. For heavier particles, they can still be in a quantum state while their position uncertainties are limited by the wavelength of background photons. We then discuss three observational signatures that may arise from a quantum superposition of primordial particles such as primordial black holes and other heavy dark matter candidates, namely, interference effects due to superpositions of the metric, transition lines in the gravitational wave spectrum due to gravitationally bound states indicating the existence of gravitons, and witnesses of quantum entanglement between massive particles and of the gravitational field.

Recent BICEP/Keck data on the cosmic microwave background, in combination with previous WMAP and Planck data, impose strong new constraints on the tilt in the scalar perturbation spectrum, $n_s$, as well as the tensor-to-scalar ratio, $r$. These constrain the number of $e$-folds of inflation, $N_{*}$, the magnitude of the inflaton coupling to matter, $y$, and the reheating temperature, $T_{\mathrm{reh}}$, which we evaluate in attractor models of inflation as formulated in no-scale supergravity. The 68% C.L. region of $(n_s,r)$ favors large values of $N_{*},y$, and $T_{\mathrm{reh}}$ that are constrained by the production of gravitinos and supersymmetric dark matter.

The Universe is not just cold dark matter and dark energy, it also contains baryons, radiation and neutrinos. The presence of these components, beyond the pressureless cold dark matter and the quasiuniform dark energy ones, imply that the single clock assumption from inflation is no longer preserved. Here we quantify this effect and show that the single-clock symmetry is ensured only on scales where baryonic effects, neutrinos effects, or sound speed are zero. These scales depend on the cosmic epoch and the Universe composition. Hence for all use and purposes of interpreting state-of-the-art and possibly forthcoming surveys, in the accessible scales, single clock symmetry cannot be said to be satisfied. Breaking the single-clock symmetry has key consequences for the study of non-Gaussian features generated by pure single-field inflation which arise from nonlinearities in the metric yielding non-Gaussianities of the local type: the $n_s-1$ and the relativistic $-5/3$ term.

In this work, we carry out the study of hidden-charm hexaquark states with the typical configurations $qqc\overline{q}\overline{q}\overline{c}$ ($q=u$, $d$, $s$). The mass spectra of hidden-charm hexaquark states are obtained within the chromomagnetic interaction model. In addition to the mass spectra analysis, we further illustrate their two-body strong decay behaviors. There exist some compact bound states which cannot decay through the strong interaction. Hopefully our results will help to search for such types of the exotic states in future experiments.

We investigate wide-angle photoproduction of the ${\eta }^{\prime }$-meson within the handbag approach to twist-3 accuracy. It turns out that, due to the gluon content of the ${\eta }^{\prime }$, this process is dominated by twist 2 in contrast with pion and $\eta$ photoproduction. Using the presently available information on the twist-2 and twist-3 distribution amplitudes and on the $\eta -{\eta }^{\prime }$ mixing, we provide prediction for the ${\eta }^{\prime }$ cross section and helicity correlations. It is argued that ${\eta }^{\prime }$ photoproduction is well suited to improve our knowledge of the two-gluon distribution amplitude.

We propose the use of isotopically highly enriched detectors for the precise study of coherent-elastic neutrino-nucleus scattering (CEvNS). CEvNS has been measured for the first time in CsI and recently confirmed with a liquid argon detector. It is expected that several new experimental setups will measure this process with increasing accuracy. Taking Ge detectors as a working example, we demonstrate that a combination of different isotopes is an excellent option to do precision neutrino physics with CEvNS, test Standard Model predictions, and probe new physics scenarios. Experiments based on this new idea can make simultaneous differential CEvNS measurements with detectors of different isotopic composition. Particular combination of observables could be used to cancel systematic errors. While many applications are possible, we illustrate the idea with three examples: testing the dominant quadratic dependence on the number of neutrons, $N$, that is predicted by the theoretical models; constraining the average neutron root mean square (rms) radius; and testing the weak mixing angle and the sensitivity to new physics. In all three cases we find that the extra sensitivity provided by this method will potentially allow high-precision robust measurements with CEvNS and particularly, will resolve the characteristic degeneracies appearing in new physics scenarios.

A concise demonstrative summary of the Symmetric-Hybrid ring design for the storage ring proton electric dipole moment experiment is presented. Critical issues such as lattice design, background electrical fields, geometrical phase, general relativity, spin coherence time, and polarimeter systematics are presented. Overall, we find that with the currently proposed design iteration the systematic error sources are reduced by orders of magnitude and that the ring alignment requirements are within currently available technology.

The Sachdev–Ye–Kitaev (SYK) model has a wormholelike solution after averaging over the fermionic couplings in the nearly ${\mathrm{AdS}}_2$ space. Even when the couplings are fixed the contribution of these wormholes continues to exist and new saddle points appear which are interpreted as “half-wormholes.” In this paper, we will study the fate of these wormholes in a model without quenched disorder, namely, a tensor model with $O(N{)}^{q-1}$ gauge symmetry whose correlation function and thermodynamics in the large $N$ limit are the same as that of the SYK model. We will restate the factorization problem linked with the wormhole threaded Wilson operator, in terms of global charges or nontrivial cobordism classes associated with disconnected wormholes. Therefore for the partition function to factorize especially at short distances, there must exist certain topological defects which break the global symmetry associated with wormholes and make the theory devoid of global symmetries. We will interpret these wormholes with added topological defects as our “half-wormholes.” We will also comment on the late time behavior of the spectral form factor, particularly its leading and subleading order contributions coming from higher genus wormholes in the gravitational sector. Finally we will show how the other nontrivial saddles from half-wormhole dominate and give rise to unusual thermodynamics in the bulk sector due to nonperturbative effects.

We study machine learning of phenomenologically relevant properties of string compactifications, which arise in the context of heterotic line bundle models. Both supervised and unsupervised learning are considered. We find that, for a fixed compactification manifold, relatively small neural networks are capable of distinguishing consistent line bundle models with the correct gauge group and the correct chiral asymmetry from random models without these properties. The same distinction can also be achieved in the context of unsupervised learning, using an autoencoder. Learning nontopological properties, specifically the number of Higgs multiplets, turns out to be more difficult, but is possible using sizeable networks and feature-enhanced datasets.

Weak-scale secluded sector dark matter can reproduce the observed dark matter relic density with thermal freeze-out within that sector. If nature is supersymmetric, three portals to the visible sector—a gauge portal, a Higgs portal, and a gaugino portal—are present. We present gamma ray spectra relevant for indirect detection of dark matter annihilation in such setups. Since symmetries in the secluded sector can stabilize dark matter, $R$-parity is unnecessary, and we investigate the impact of $R$-parity violation on annihilation spectra. We present limits from the Fermi Large Area Telescope observations of dwarf galaxies and projections for Cherenkov Telescope Array observations of the galactic center. Many of our results are also applicable to generic, nonsupersymmetric setups.

The next-generation neutrino experiment JUNO will determine the solar oscillation parameters—${\sin }^2{\theta }_{12}$ and $\mathrm{\Delta }{m}_{21}^2$—with great accuracy, in addition to measuring ${\sin }^2{\theta }_{13}$, $\mathrm{\Delta }{m}_{31}^2$, and the mass ordering. In parallel, the continued study of solar neutrinos at Hyper-Kamiokande will provide complementary measurements in the solar sector. In this paper, we address the expected sensitivity to nonuniversal and flavor-changing nonstandard interactions (NSI) with $d$-type quarks from the combination of these two future neutrino experiments. We also show the robustness of their measurements of the solar parameters ${\sin }^2{\theta }_{12}$ and $\mathrm{\Delta }{m}_{21}^2$ in the presence of NSI. We study the impact of the exact experimental configuration of the Hyper-Kamiokande detector, and conclude it is of little relevance in this scenario. Finally, we find that the LMA-D solution is expected to be present if no additional input from nonoscillation experiments is considered.

In this work, we study the lepton flavor and lepton number violating $B_c$ meson decays via two intermediate on-shell Majorana neutrinos $N_j$ into two charged leptons and a charged pion $B_c^{\pm }\to {\mu }^{\pm }{N}_j\to {\mu }^{\pm }{\tau }^{\pm }{\pi }^{\mp }$. We evaluated the possibility to measure the modulation of the decay width along the detector length produced as a consequence of the lepton flavor violating process, in a scenario where the heavy neutrinos masses range between $2.0\mathrm{GeV}\le M_N\le 6.0\mathrm{GeV}$. We study some realistic conditions, which could lead to the observation of this phenomenon at future $B$ factories, such as the HL-LHCb.

We study the optimization of a green-field, two-baseline reactor experiment with respect to the sensitivity for electron antineutrino disappearance in search of a light sterile neutrino. We consider both commercial and research reactors and identify as key factors the distance of closest approach and detector energy resolution. We find that a total of 5 tons of detectors deployed at a commercial reactor with a closest approach of 25 m can probe the mixing angle ${\sin }^{2}2\theta$ down to $\sim 5\times {10}^{-3}$ around $\mathrm{\Delta }{m}^2\sim 1{\mathrm{eV}}^2$. The same detector mass deployed at a research reactor can be sensitive up to $\mathrm{\Delta }{m}^2\sim 20–30{\mathrm{eV}}^2$ assuming a closest approach of 3 m and excellent energy resolution, such as that projected for the Taishan Antineutrino Observatory. We also find that lithium doping of the reactor could be effective in increasing the sensitivity for higher $\mathrm{\Delta }{m}^2$ values.

In this article we calculate the post-Newtonian limit of a general class of scalar-nonmetricity theories of gravity. The action is assumed to be a free function of the nonmetricity scalar, the kinetic term of the scalar field, two derivative couplings and the scalar field itself. We use the parametrized post-Newtonian formalism to solve the arising field equations for the case of a massless scalar field in order to compare several subclasses of this theory to solar system observations. In particular, we find several classes of theories which are indistinguishable from general relativity on the post-Newtonian level and therefore, should be studied further. Most remarkably, we find that this is the generic case, while a post-Newtonian limit that deviates from general relativity occurs only for a particular coupling between the scalar field and nonmetricity.

We study a minimal extension of a recently proposed modification of general relativity that draws on concepts from topological field theory to resolve aspects of the cosmological constant problem. In the original model, the field content of general relativity was augmented to include a gauge field and an adjoint-valued two-form without modifying the classical gravitational dynamics. Here we include a kinetic term for the gauge field which sources fluctuations of the cosmological constant. We then study spherically symmetric black holes and a simple homogeneous, isotropic cosmological model predicted by the extended theory. For the black hole case, we observe deviations near the event horizon as well as a “charge”-like behavior induced by the gauge field. In the cosmological case, $\dot{H}$ is always positive and some solutions asymptote to a constant $H$.