We provide a detailed study of reheating in the kination regime where particle content is created by gravitational production of massive scalars mutually interacting with a massless scalar field. The produced particles subsequently decay into massless particles eventually reheating the Universe. We aim for a more precise picture using Boltzmann equations and decay rates obtained by methods of quantum field theory in curved spacetime. By numerical calculations it is found that after inflation the Universe ends up being dominated by ordinary matter for a while before the radiation-dominated era. The reheating temperature is found to be in the ${10}^4–{10}^{12}\mathrm{GeV}$ regime.

We study the cosmological constant ($\mathrm{\Lambda }$) in the standard $\mathrm{\Lambda }$ cold dark matter model by introducing the graduated dark energy (gDE) characterized by a minimal dynamical deviation from the null inertial mass density of the $\mathrm{\Lambda }$ in the form ${\rho }_{\text{inert}}\propto {\rho }^{\lambda }<0$ with $\lambda <1$ being a ratio of two odd integers, for which its energy density $\rho$ dynamically takes negative values in the finite past. For large negative values of $\lambda$, it creates a phenomenological model described by a smooth function that approximately describes the $\mathrm{\Lambda }$ spontaneously switching sign in the late Universe to become positive today. We confront the model with the latest combined observational datasets of $\mathrm{Planck}+\mathrm{baryon}\mathrm{acoustic}\mathrm{oscillations}+\mathrm{supernova}+H$. It is striking that the data predict bimodal posterior probability distributions for the parameters of the model along with large negative $\lambda$ values; the new maximum significantly excludes the $\mathrm{\Lambda }$, and the old maximum contains the $\mathrm{\Lambda }$. The improvement in the goodness of fit for the $\mathrm{\Lambda }$ reaches highly significant levels, $\mathrm{\Delta }{\chi }_{\min }^2=6.4$, for the new maxima, while it remains at insignificant levels, $\mathrm{\Delta }{\chi }_{\min }^2\lesssim 0.02$, for the old maxima. We show that, in contrast to the old maxima, which do not distinguish from the $\mathrm{\Lambda }$, the new maxima agree with the model-independent $H_0$ measurements, high-precision $\mathrm{Ly}\text{−}\alpha$ data, and model-independent $Om{h}^2$ diagnostic estimates. Our results provide strong hints of a spontaneous sign switch in the cosmological constant and lead us to conjecture that the Universe has transitioned from anti-de Sitter vacua to de Sitter vacua, at a redshift $z\approx 2.32$, and triggered the late-time acceleration, and suggests looking for such mechanisms in string theory constructions.

We explore the bound of the trans-Planckian censorship conjecture on an inflation model with multiple stages. We show that if the first inflationary stage is responsible for the primordial perturbations in the cosmic microwave background window, the $e$-folding number of each subsequent stage will be bounded by the energy scale of the first stage. This seems to imply that the lifetime of the current era of accelerated expansion (regarded as one of the multiple inflationary stages) might be a probe for distinguishing inflation from its alternatives. We also present a multistage inflation model in a landscape consisting of anti–de Sitter vacua separated by potential barriers.

The advent of the Gaia era has led to potentially revolutionary understanding of dark matter (DM) dynamics in our galaxy, which has important consequences for direct detection (DD) experiments. In this paper, we study how the empirical DM velocity distribution inferred from Gaia-sausage, a dominant substructure in the solar neighborhood, affects the interpretation of DD data. We survey different classes of operators in the nonrelativistic effective field theory that could arise from several relativistic benchmark models and emphasize that the Gaia velocity distribution could modify both the total number of events as well as the shape of the differential recoil spectra, the two primary observables in DD experiments. Employing the Euclideanized signal method, we investigate the effects of the Gaia distribution on reconstructing DM model parameters and identifying the correct DM model given a positive signal at future DD experiments. We find that for light DM with mass $\sim 10\mathrm{GeV}$, the Gaia distribution poses an additional challenge for characterizing DM interactions with ordinary matter, which may be addressed by combining complementary DD experiments with different targets and lowering the detection threshold. Meanwhile, for heavy DM with mass above $\sim 30\mathrm{GeV}$, depending on the type of DM model, there could be a (moderate) improvement in the sensitivity at future DD experiments.

We study radial oscillations of non-rotating neutron stars (NSs) in four-dimensional general relativity. The interior of the NS was modeled within a recently proposed multicomponent realistic equation of state (EoS) with the induced surface tension (IST). In particular, we considered the IST EoS with two sets of model parameters, that both reproduce all the known properties of normal nuclear matter, give a high quality description of the proton flow constraint, hadron multiplicities created in nuclear-nuclear collisions, consistent with astrophysical observations and the observational data from the NS-NS merger. We computed the 12 lowest radial oscillation modes, their frequencies and corresponding eigenfunctions, as well as the large frequency separation for six selected fiducial NSs (with different radii and masses of 1.2, 1.5 and 1.9 solar masses) of the two distinct model sets. The calculated frequencies show their continuous growth with an increase of the NS central baryon density. Moreover, we found correlations between the behavior of the first eigenfunction calculated for the fundamental mode, the adiabatic index and the speed of sound profile, which could be used to probe the internal structure of NSs with the asteroseismology data.

Many theories beyond the Standard Model postulate short-range modifications to gravity which produce deviations of Newton’s gravitational potential from a strict $1/r$ dependence. It is common to analyze experiments searching for these modifications using a potential of the form $V^{\prime }(r)=-\frac{GMm}{r}[1+\alpha \exp (-r/\lambda )]$. The best present constraints on $\alpha$ for $\lambda <100\mathrm{nm}$ come from neutron scattering and often employ comparisons of different measurements of the coherent neutron scattering amplitudes $b$. We analyze the internal consistency of existing data from two different types of measurements of low-energy neutron scattering amplitudes: neutron interferometry, which involves squared momentum transfers $q^2=0$, and neutron gravity reflectometry, which involves squared momentum transfers $q^2=8m{V}_{\mathrm{opt}}$ where $m$ is the neutron mass and $V_{\mathrm{opt}}$ is the neutron optical potential of the medium. We show that the fractional difference $\frac{\mathrm{\Delta }b}{|b|}$ averaged over the seven elements where high precision data exist on the same material from both measurement methods is $[2.2\pm 1.4]\times {10}^{-4}$. We also show that $\frac{\mathrm{\Delta }b}{|b|}$ for these data is insensitive both to exotic Yukawa interactions and also to the electromagnetic neutron-atom interactions proportional to the neutron-electron scattering length $b_{ne}$ and the neutron polarizability scattering amplitude $b_{\mathrm{pol}}$. This result will be useful in any future global analyses of neutron scattering data to determine $b_{ne}$ and bound $\alpha$ and $\lambda$. We also discuss how various neutron interferometric and scattering techniques with cold and ultracold neutrons can be used to improve the precision of $b$ measurements and make some specific proposals.

We study the trident process in laser pulses. We provide exact numerical results for all contributions, including the difficult exchange term. We show that all terms are in general important for a short pulse. For a long pulse, we identify a term that gives the dominant contribution even if the intensity is only moderately high, $a_0\gtrsim 1$, which is an experimentally important regime where the standard locally constant field (LCF) approximation cannot be used. We show that the spectrum has a richer structure at $a_0\sim 1$, compared to the LCF regime $a_0\gg 1$. We study the convergence to LCF as $a_0$ increases and how this convergence depends on the momentum of the initial electron. We also identify the terms that dominate at high energy.

We study the discovery prospects of the charged Higgs boson in the context of multi-Higgs models in certain beyond the Standard Model scenarios. We classify models into three categories based on the charged Higgs coupling properties: gaugophobic, fermiophobic, and chromophobic. In each case, we identify viable modes of discovery and present LHC analysis for discovery. We find that extensions of the Standard Model in which the charged Higgs boson does not couple to colored particles offer the best possible avenues for discovery.

The inflation within the minimal supersymmetric standard model (MSSM) is proposed, where the inflaton field is a combination of the Higgs, squark, and slepton states. While the inflationary phase is fully governed by the electron Yukawa superpotential coupling, the fields’ condensates float along the flat $D$-term trajectory. This predicts the MSSM parameter $\tan \beta \simeq 13.1$ determined via the value of the curvature perturbation amplitude. The values of the scalar spectral index and the tensor-to-scalar ratio are predicted to be $n_s\simeq 0.966$ and $r=0.00118$. The postinflation reheating of the Universe proceeds by the radiative decay of the inflaton to the two gluons ($\varphi \to gg$) with the reheating temperature $T_r\simeq 1.4\times {10}^7\mathrm{GeV}$.

We observe that four peaks seen in the high energy part of the ${\mathrm{\Omega }}_b$ spectrum of the recent LHCb experiment are in remarkable agreement with predictions made for molecular ${\mathrm{\Omega }}_b$ states stemming from the meson-baryon interaction, with an approach that applied to the ${\mathrm{\Omega }}_c$ states gives rise to three states in good agreement with experiment in masses and widths. While the statistical significance of the peaks prevents us from claims of states at the present time, the agreement found should be an incentive to look at this experiment with increased statistics to give an answer to this suggestive idea.

This paper presents the first calculations of the parity-violating polarization asymmetry and forward-backward asymmetry of the $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}(\gamma )$ process at a center-of-mass energy of 10.579 GeV with up to one-loop electroweak radiative corrections. The calculations are relevant for future precision electroweak measurements at the Belle II experiment, which is now collecting data at the SuperKEKB $e^{+}{e}^{-}$ collider with a center-of-mass energy at the mass of the $\mathrm{\Upsilon }(4S)$ resonance. In this paper we take under full control the bremsstrahlung process at the conditions of Belle II/SuperKEKB, and the possibilities for a soft photon approach are discussed. The scale of the obtained relative corrections to the parity-violating and forward-backward asymmetries is significant and the scattering angle dependencies of the asymmetries is nontrivial. As an additional validation cross-check using an independent formulation, the calculated asymmetries are compared to results from the $\mathcal{K}\mathcal{K}$ Monte Carlo generator.

Using a data sample of $772\times {10}^{6}B\overline{B}$ pairs collected on the $\mathrm{\Upsilon }(4S)$ resonance with the Belle detector at the KEKB asymmetric energy $e^{+}{e}^{-}$ collider, we report the observation of $B^0\to p\overline{p}{\pi }^{+}{\pi }^{-}$ and the first observation of $B^{+}\to p\overline{p}{\pi }^{+}{\pi }^0$. We measure a decay branching fraction of $(0.83\pm 0.17\pm 0.17)\times {10}^{-6}$ in $B^0\to p\overline{p}{\pi }^{+}{\pi }^{-}$ for $M_{{\pi }^{+}{\pi }^{-}}<1.22\mathrm{GeV}/c^2$ with a significance of 5.5 standard deviations. The contribution from $B^0\to p\overline{p}{K}^0$ is excluded. We measure a decay branching fraction of $(4.58\pm 1.17\pm 0.67)\times {10}^{-6}$ for $B^{+}\to p\overline{p}{\pi }^{+}{\pi }^0$ with $M_{{\pi }^{+}{\pi }^0}<1.3\mathrm{GeV}/c^2$ with a significance of 5.4 standard deviations. We study the difference of the $M_{p\overline{p}}$ distributions in $B^0\to p\overline{p}{\pi }^{+}{\pi }^{-}$ and $B^{+}\to p\overline{p}{\pi }^{+}{\pi }^0$.

A search for proton decay into three charged leptons has been performed by using $0.37\mathrm{Mton}·\mathrm{years}$ of data collected in Super-Kamiokande. All possible combinations of electrons, muons, and their antiparticles consistent with charge conservation were considered as decay modes. No significant excess of events has been found over the background, and lower limits on the proton lifetime divided by the branching ratio have been obtained. The limits range between $9.2\times {10}^{33}$ and $3.4\times {10}^{34}\mathrm{years}$ at 90% confidence level, improving by more than an order of magnitude upon limits from previous experiments. A first limit has been set for the $p\to {\mu }^{-}{e}^{+}{e}^{+}$ mode.

Results are reported from a search for new physics beyond the standard model in proton-proton collisions in final states with a single lepton; multiple jets, including at least one jet tagged as originating from the hadronization of a bottom quark; and large missing transverse momentum. The search uses a sample of proton-proton collision data at $\sqrt{s}=13\mathrm{TeV}$, corresponding to $137{\mathrm{fb}}^{-1}$, recorded by the CMS experiment at the LHC. The signal region is divided into categories characterized by the total number of jets, the number of bottom quark jets, the missing transverse momentum, and the sum of masses of large-radius jets. The observed event yields in the signal regions are consistent with estimates of standard model backgrounds based on event yields in the control regions. The results are interpreted in the context of simplified models of supersymmetry involving gluino pair production in which each gluino decays into a top quark-antiquark pair and a stable, unobserved neutralino, which generates missing transverse momentum in the event. Scenarios with gluino masses up to about 2150 GeV are excluded at 95% confidence level (or more) for neutralino masses up to 700 GeV. The highest excluded neutralino mass is about 1250 GeV, which holds for gluino masses around 1850 GeV.

We use a method to calculate the hadron’s charge radius without model-dependent momentum extrapolations. The method does not require the additional quark propagator inversions on the twisted boundary conditions or the computation of the momentum derivatives of quark propagators and thus is easy to implement. We apply this method to the calculation of pion charge radius $⟨r_{\pi }^2⟩$. For comparison, we also determine $⟨r_{\pi }^2⟩$ with the traditional approach of computing the slope of the form factors. The new method produces results consistent with those from the traditional method and with statistical errors 1.5–1.9 times smaller. For the four gauge ensembles at the physical pion masses, the statistical errors of $⟨r_{\pi }^2⟩$ range from 2.1% to 4.6% by using $\lesssim 50$ configurations. For the ensemble at $m_{\pi }\approx 340\mathrm{MeV}$, the statistical uncertainty is even reduced to a subpercent level.

The relationship between $T\overline{T}$ deformations and the uniform light-cone gauge, first noted by Baggio and Sfondrini [Phys. Rev. D 98, 021902 (2018)], provides a powerful generating technique for deformed models. We recall this construction, distinguishing between changes of the gauge frame, which do not affect the theory, and genuine deformations. We investigate the geometric interpretation of the latter and argue that they affect the global features of the geometry before gauge fixing. Exploiting a formal relation between uniform light-cone gauge and static gauge in a $T$-dual frame, we interpret such a change as a $T$-duality–shift–$T$-duality transformation involving the two light-cone coordinates. In the static-gauge picture, the $T\overline{T}$ Castillejo-Dalitz-Dyson factor then has a natural interpretation as a Drinfeld-Reshetikhin twist of the worldsheet $S$ matrix. To illustrate these ideas, we find the geometries yielding a $T\overline{T}$ deformation of the worldsheet $S$ matrix of $pp$-wave and Lin-Lunin-Maldacena backgrounds.

In the ${\mathrm{AdS}}_3/{\mathrm{CFT}}_2$ setup, we elucidate how gauge-invariant boundary patterns of entanglement of the CFT vacuum are encoded into the bulk via the coefficient dynamics of an $A_{N-3}$, $N\ge 4$, cluster algebra. In the static case, this dynamics of encoding manifests itself in kinematic space, which is a copy of de Sitter space ${\mathrm{dS}}_2$, in a particularly instructive manner. For a choice of partition of the boundary into $N$ regions, the patterns of entanglement, associated with conditional mutual information of overlapping regions, are related to triangulations of geodesic $N$-gons. Such triangulations are then mapped to causal patterns in kinematic space. For a fixed $N$, the space of all causal patterns is related to the associahedron ${\mathcal{K}}^{N-3}$, an object well known from previous studies on scattering amplitudes. On this space of causal patterns, cluster dynamics acts by a recursion provided by Zamolodchikov’s $Y$ system of type $(A_{N-3},A_1)$. We observe that the space of causal patterns is equipped with a partial order and is isomorphic to the Tamari lattice. The mutation of causal patterns can be encapsulated by a walk of $N-3$ particles interacting in a peculiar manner in the past light cone of a point of ${\mathrm{dS}}_2$.

We consider the holographic Abelian Higgs model and show that, in the absence of the scale symmetry breaking effect, chiral symmetry breaking gives linear confinement where the slope is given by the value of the chiral condensation. The model can be considered either as the theory of superconductivity or as the axial sector of QCD depending on the interpretation of the charge. We also provided a few models with linear confinement.

Two topics in soft collinear effective theory (SCET) for gravitational interactions are explored. First, the collinear Wilson lines—necessary building blocks for maintaining multiple copies of diffeomorphism invariance in gravity SCET—are extended to all orders in the SCET expansion parameter $\lambda$, where it has only been known to $O(\lambda )$ in the literature. Second, implications of reparametrization invariance (RPI) for the structure of gravity SCET Lagrangians are studied. The utility of RPI is illustrated by an explicit example in which $O({\lambda }^2)$ hard interactions of a collinear graviton are completely predicted by RPI from its $O(\lambda )$ hard interactions. It is also pointed out that the multiple diffeomorphism invariances and RPI together require certain relations among $O(\lambda )$ terms, thereby reducing the number of $O(\lambda )$ terms that need to be fixed by matching onto the full theory in the first place.

We look for classical traces of the Unruh effect in gravity waves. For this purpose, we start considering a white noise state of gravity waves on the surface of a water basin and calculate the two- and four-point functions of the Fourier transform of the surface height field with respect to accelerated observers. The influence of the basin boundaries and possible deviations from Gaussianity in the white noise state are considered in order to approximate conditions attainable in the laboratory. Eventually, we make the basin infinitely large in order to make contact between our classical results and quantum ones derived in free space. We hope that our results help to strengthen the bridge between the Unruh effect and this classical analog.