We study the predictions for the matter redshift-space power spectrum and correlation function of a Lagrangian-space Gaussian ansatz introduced in a previous work. This model is a natural extension of the Zeldovich approximation, where the displacement and velocity power spectra are determined by the equations of motion, instead of being set equal to the linear power spectrum. It does not contain any free parameter. As for the real-space statistics, we find that this Lagrangian-space approach is much more efficient for the correlation functions than for the power spectra. The damping of the baryon acoustic oscillations (BAO) oscillations is well recovered, but there is a large smooth drift from the simulations in the power spectra. The multipoles of the correlation functions are well recovered on BAO scales, with an accuracy of 2% for ${\xi }_0^s$ down to $10h^{-1}\mathrm{Mpc}$, and of 3% for ${\xi }_2^s$ down to $26h^{-1}\mathrm{Mpc}$, at $z\ge 0.35$.

We show that the entropy of cosmological perturbations originating as quantum vacuum fluctuations in the very early universe, including the contribution of the leading nonlinear interactions, can be viewed as momentum space entanglement entropy between sub- and super-Hubble modes. The interactions between these modes cause decoherence of the super-Hubble fluctuations which, in turn, leads to a nonvanishing entropy of the reduced density matrix corresponding to the super-Hubble inhomogeneities. In particular, applying this to inflationary cosmology reveals that the entanglement entropy produced by leading order nonlinearities dominates over that coming from the squeezing of the vacuum state unless inflation lasts for a very short period. Furthermore, demanding that this entanglement entropy be smaller than the thermal entropy at the beginning of the radiation phase of standard cosmology leads to an upper bound on the duration of inflation which is similar to what is obtained from the trans-Planckian censorship conjecture.

We have conducted extensive lattice simulations to study the postinflation dynamics of multifield models involving nonminimal couplings. We explore the parameter dependence of preheating in these models and describe the various time scales that control such nonlinear processes as energy transfer, rescattering, and the approach to radiation domination and thermalization. In the limit of large nonminimal couplings (${\xi }_I\sim 100$), we find that efficient transfer of energy from the inflaton condensate to radiative degrees of freedom, emergence of a radiation-dominated equation of state, and the onset of thermalization each consistently occur within $N_{\mathrm{reh}}\lesssim 3$ $e$-folds after the end of inflation, largely independent of the values of the other couplings in the models. The exception is the case of negative ellipticity, in which there is a misalignment between the dominant direction in field space along which the system evolves and the larger of the nonminimal couplings ${\xi }_I$. In those cases, the field-space-driven parametric resonance is effectively shut off. More generally, the competition between the scalar fields’ potential and the field-space manifold structure can yield interesting phenomena such as two-stage resonances. Across many regions of parameter space, we find efficient re-scattering between the distinct fields, leading to a partial memory loss of the shape of the initial fluctuation spectrum. Despite the explosive particle production, which can lead to a quick depletion of the background energy density, the nonlinear processes do not induce any superhorizon correlations after the end of inflation in these models, which keeps predictions for cosmic microwave background observables unaffected by the late-time amplification of isocurvature fluctuations. Hence the excellent agreement between primordial observables and recent observations is preserved for this class of models, even when we consider postinflation dynamics.

We propose a new single field inflation model in which the usual slow-roll inflation is joined to a new period of slow-climb and slow-roll inflation through a short intermediate noninflationary phase. We then show that primordial curvature perturbations can be enhanced at small scales, a sizable amount of primordial black holes (PBHs) can be produced which make up most of dark matter, the gravitational waves (GWs) induced by scalar metric perturbations that accompany with the formation of PBHs can be detectable by future GW experiments, and last but not least, our model is compatible with the latest cosmic microwave background observations. Remarkably, the GW spectrum displays a unique oscillating character in the ultraviolet regions which originates from the short noninflationary phase. A detection of such oscillations in the GW spectrum may suggest the existence of such a noninflationary phase in the whole inflation, thus providing us a chance to reveal an interesting period in the evolution of the early Universe and distinguish our model from others.

We investigate the surface tension of strange quark stars by making use of a color-flavor-locked (CFL) equation of state. Compact objects with anisotropic pressures provide richer systems for studying surface tension variations, and establishing physically viable ranges of parameters in maintaining hydrostatic equilibrium of quark matter at densities exceeding that of nuclear material. The strange quark mass, the QCD gap energy, and the MIT bag constant are key parameters in the CFL equation of state used, and thus feature in calculations of the surface tension.

We estimate the sensitivity of LHAASO telescope for the large angular scale diffuse $\gamma$-ray flux in multi-TeV—multi-PeV energy range. We discuss possible sources of the signal in this energy range including the guaranteed flux from cosmic ray interactions in the interstellar medium and possible flux from decaying dark matter. We show that LHAASO will be able to detect the diffuse cosmic ray induced $\gamma$-ray flux up to high Galactic latitude regions thus providing firm identification of the Galactic cosmic ray component of the astrophysical neutrino signal detected by IceCube and clarification of the nature of the knee feature of the cosmic ray spectrum. Comparing the diffuse flux sensitivity with the diffuse $\gamma$-ray flux expected from the dark matter decays, we show LHAASO will be able to detect the $\gamma$-ray signal from dark matter particles of PeV–EeV mass decaying on the time scale up to $3\times {10}^{29}\mathrm{s}$.

We present a simple new approach to the treatment of Coulomb-nuclear interference and form-factor effects in high-energy proton-proton scattering in the context of an eikonal model for the spin-averaged scattering amplitude. We show that the corrections to the nuclear and Coulomb amplitudes do not depend sensitively on the details of the eikonal amplitude and can be taken as universal, and present parametrizations for the necessary corrections. We also present a simple model for the nuclear scattering amplitude useful for data analysis at small momentum transfer which builds in the proper nuclear phase and the diffraction zeros in the real and imaginary parts of the amplitude.

The existing transformation from a relativistic real scalar field to a complex nonrelativistic scalar field by Namjoo, Guth, and Kaiser is generalized from Minkowski space to a more general background metric. In that case the transformation is not purely algebraic any more but determined by a differential equation. We apply the generalized transformation to a real scalar with ${\varphi }^4$ interaction on an Friedmann-Lemaître-Robertson-Walker cosmologically expanding background and calculate the resulting nonrelativistic action up to second order in small parameters. We also show that the transformation can be interpreted as a Bogoliubov transformation between relativistic and nonrelativistic creation and annihilation operators and comment on emerging symmetries in the nonrelativistic theory.

Composite Higgs models feature new strong dynamics leading to the description of the Higgs boson as a bound state arising from the breaking of a global (flavor) symmetry. These models generally include light states generated by the same dynamics, the detection of which may present the first observable signs of compositeness. One such state is a pseudoscalar boson resulting from the breaking of a $U(1)$ symmetry common to most composite setups, and whose hints are expected to be visible through low-mass resonance searches at present and future hadron and lepton colliders. In this work we study the phenomenology of this pseudoscalar field. We show that, for a light state, bottom quark loop effects dominantly impact the production cross section and considerably modify the decay pattern. Moreover, we make a case for targeted low-mass analyses at future lepton colliders, with an emphasis on high-luminosity machines aiming to operate at low center-of-mass energies. We present a simplified outline of a search for this light pseudoscalar at one such machine, considering electron-positron collisions at the $Z$-pole. We focus on a signature arising from the pseudoscalar decay into a pair of hadronic taus and a production mode association with a pair of leptons of opposite electric charges, and compare cut and count methods with machine learning methods.

We discuss the lattice formulation of the ’t Hooft surface, that is, the two-dimensional surface operator of a dual variable. The ’t Hooft surface describes the world sheets of topological vortices. We derive the formulas to calculate the expectation value of the ’t Hooft surface in the multiple-charge lattice Abelian Higgs model and in the lattice non-Abelian Higgs model. As the first demonstration of the formula, we compute the intervortex potential in the charge-2 lattice Abelian Higgs model.

We focus on the four-dimensional central-branch Wilson fermion, which makes good use of six species at the central branch of the Wilson Dirac spectrum and possesses the extra $U(1{)}_{\overline{V}}$ symmetry. With introducing new insights we discuss the prohibition of additive mass renormalization for all the six species, spontaneous symmetry breaking (SSB) of $U(1{)}_{\overline{V}}$ in strong-coupling quantum chromodynamics (QCD), the absence of the sign problem, and the usefulness for many-flavor QCD simulation. We then construct several varieties of the central-branch fermions and study their properties. In particular, we investigate the two-flavor version, where the Dirac spectrum has seven branches and two species live at the central branch. Although the hypercubic symmetry is broken, the other symmetries are the same as those of the original one. We study this setup in terms of lattice perturbation theory, strong-coupling QCD, the absence of sign problem, and the parameter tuning for Lorentz symmetry restoration. By comparing the properties of the original and two-flavor version, we find that the existence of hypercubic symmetry as well as $U(1{)}_{\overline{V}}$ is essential for the absence of additive mass renormalization of all the central-branch species. As the other two-flavor version, we investigate the central-branch staggered-Wilson fermion, which is obtained from the eight-flavor central-branch Wilson fermion via spin diagonalization. We argue that it is free from any additive mass renormalization and is regarded as a minimally doubled fermion with less symmetry breaking.

We extend dilaton chiral perturbation theory (dChPT) to include the taste splittings in the Nambu-Goldstone sector observed in lattice simulations of near-conformal theories with staggered fermions. We then apply dChPT to a recent simulation by the LSD Collaboration of the SU(3) gauge theory with 8 fermions in the fundamental representation, which is believed to exhibit near-conformal behavior in the infrared, and in which a light singlet scalar state, nearly degenerate with the pions, has been found. We find that the mesonic sector of this theory can be successfully described by dChPT, including, in particular, the mesonic taste splittings found in the simulation. We confirm that current simulations of this theory are in the “large-mass” regime.

We demonstrate how an effective density of states can be derived from the S-matrix describing a coupled-channel system. Besides the locations of poles, the phase of the determinant of the S-matrix encodes essential details in characterizing the dynamics of resonant and nonresonant interactions. The density of states is computed for the two channel scattering problem ($\pi \pi$, $K\overline{K}$, S-wave), and the influences from the various dynamical structures: poles, roots, branch cuts, and Riemann sheets, are examined.

Very recently, the BABAR Collaboration indicated that there exists an explicit enhancement structure near 2.2 GeV when focusing on the $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}$ process again, which inspires our interest in studying the production of higher $\rho$ mesonic states. Since the branching ratio of ${\pi }^{+}{\pi }^{-}$ channel of $D$–wave $\rho$ states are much smaller than $S$–wave states, we choose $\rho (1900)$ and $\rho (2150)$ as the intermediate states in $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}$, where $\rho (1900)$ and $\rho (2150)$ are treated as $\rho (3S)$ and $\rho (4S)$ states, respectively. Our result indicates that the BABAR’s data of $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}$ around 2 GeV can be depicted well, which shows that this enhancement structure near 2.2 GeV existing in $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}$ can be due to the contribution from two $\rho$ mesons, $\rho (1900)$ and $\rho (2150)$. Additionally, this conclusion can be enforced by the consistence of the extracted values of ${\mathrm{\Gamma }}_{e^{+}{e}^{-}}\mathcal{B}({\pi }^{+}{\pi }^{-})$ of $\rho (1900)$ and $\rho (2150)$ in the whole fitting processes and the corresponding theoretical calculations. The present study of $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}$ data may provide valuable information to establish the $\rho$ meson family.

A unitary matrix integral that appears in the low-energy limit of QCD-like theories with quarks in real representations of the gauge group at finite chemical potential is analytically evaluated and expressed as a pfaffian. Its application to the Gaussian orthogonal ensemble and the Gaussian unitary ensemble (GOE-GUE) crossover in random matrix theory is discussed. An analogous unitary integral for QCD-like theories with quarks in pseudoreal representations of the gauge group is also evaluated.

We present new contributions to the decay matrix element ${\mathrm{\Gamma }}_{12}^q$ of the $B_q-{\overline{B}}_q$ mixing complex, where $q=d$ or $s$. Our new results constitute the order ${\alpha }_s^2{N}_f$ corrections to the penguin contributions to the Wilson coefficients entering ${\mathrm{\Gamma }}_{12}^q$ with full dependence on the charm quark mass. This is the first step toward the prediction of the $CP$ asymmetry $a_{\mathrm{fs}}^q$ quantifying $CP$ violation in mixing at next-to-next-to-leading logarithmic order (NNLO) in quantum chromodynamics (QCD) and further improves the prediction of the width difference ${\mathrm{\Delta }\mathrm{\Gamma }}_q$ between the two neutral-meson eigenstates. We find a sizable effect from the nonzero charm mass and our partial NNLO result decreases the NLO penguin corrections to $a_{\mathrm{fs}}^q$ by 37% and those to ${\mathrm{\Delta }\mathrm{\Gamma }}_q$ by 16%. We further update the Standard-Model NLO predictions for $a_{\mathrm{fs}}^q$ and the ratio of the width and mass differences of the $B_q$ eigenstates: If we express the results in terms of the pole mass of the bottom quark, we find $a_{\mathrm{fs}}^s=(2.07\pm 0.10)\times {10}^{-5}$, $a_{\mathrm{fs}}^d=(-4.71\pm 0.24)\times {10}^{-4}$, $\mathrm{\Delta }{\mathrm{\Gamma }}_s/\mathrm{\Delta }{M}_s=(4.33\pm 1.26)\times {10}^{-3}$, and $\mathrm{\Delta }{\mathrm{\Gamma }}_d/\mathrm{\Delta }{M}_d=(4.48\pm 1.19)\times {10}^{-3}$. In the $\overline{\mathrm{MS}}$ scheme these numbers read $a_{\mathrm{fs}}^s=(2.04\pm 0.11)\times {10}^{-5}$, $a_{\mathrm{fs}}^d=(-4.64\pm 0.25)\times {10}^{-4}$, $\mathrm{\Delta }{\mathrm{\Gamma }}_s/\mathrm{\Delta }{M}_s=(4.97\pm 1.02)\times {10}^{-3}$, and $\mathrm{\Delta }{\mathrm{\Gamma }}_d/\mathrm{\Delta }{M}_d=(5.07\pm 0.96)\times {10}^{-3}$.

Vector boson scattering is a well known probe of electroweak symmetry breaking. Here we study a related process of two electroweak vector bosons scattering into a vector boson and a Higgs boson ($VV\to Vh$, $V=W$, $Z$). This process exhibits tree level interference and grows with energy if the Higgs couplings to electroweak bosons deviate from their Standard Model values. Therefore, this process is particularly sensitive to the relative sign of the ratio of the coupling between the Higgs and the $W$ and $Z$, ${\lambda }_{WZ}$. In this work we show that a high energy lepton collider is well suited to study this process through vector boson fusion, estimate the potential sensitivity to this ratio, and show that a relatively modest amount of data can exclude ${\lambda }_{WZ}\simeq -1$.

Holography has allowed the exact solution of a small number of large $N_c$ gauge theories. Among these is an $\mathcal{N}=2$ gauge theory of quarks interacting with $\mathcal{N}=4$ gauge fields. The temperature chemical potential phase diagram for this theory in the presence of a magnetic field is exactly known and shows first and second order chiral symmetry restoration transitions and a critical point. Here we extend this phase diagram to imaginary chemical potential to seek structure at small real $\mu$ and imaginary $\mu$ that help to reconstruct the large real $\mu$ phase structure. We also explore a phenomenologically deformed version of the theory where the critical point can be moved into the imaginary chemical potential plane. In particular, we observe that when the transition is second order in these theories, there are naturally two distinct transitions—one for the onset of density and one for chiral symmetry restoration. In addition, the phase diagram has boundaries of regions where metastable vacua exist and these boundaries, as well as the phase boundaries, converge at the critical point. These observations may point to techniques for the study of the QCD critical point either on the lattice or using heavy ion collision data.

We propose to slightly generalize the DeWitt-Schwinger adiabatic renormalization subtractions in curved space to include an arbitrary renormalization mass scale $\mu$. The new predicted running for the gravitational couplings are fully consistent with decoupling of heavy massive fields. This is a somewhat improvement with respect to the more standard treatment of minimal (DeWitt-Schwinger) subtractions via dimensional regularization. We also show how the vacuum metamorphosis model emerges from the running couplings.