We introduce a new approach for cosmological parameter estimation based on the information-theoretical Jensen-Shannon divergence (${\mathcal{D}}_{\mathrm{JS}}$), calculating it for models in the restricted parameter space $\{H_0,w_0,w_a\}$, where $H_0$ is the value of the Hubble constant today, and $w_0$ and $w_a$ are dark energy parameters, with the other parameters held fixed at their best-fit values from the Planck 2018 data. As an application, we investigate the $H_0$ tension between the Planck temperature power spectrum data (TT) and the local astronomical data by comparing the $\mathrm{\Lambda }\mathrm{CDM}$ model with the $w\mathrm{CDM}$ and the $w_0{w}_a\mathrm{CDM}$ dynamic dark energy models. We find agreement with other works using the standard Bayesian inference for parameter estimation; in addition, we show that while the ${\mathcal{D}}_{\mathrm{JS}}$ is equally minimized for both values of $H_0$ along the $(w_0,w_a)$ plane, the lines of degeneracy are different for each value of $H_0$. This allows for distinguishing between the two, once the value of either $w_0$ or $w_a$ is known.

The weak lensing magnification of type Ia supernovae (SNe Ia) is sensitive to the clustering of matter and provides an independent cosmological probe complementary to SN Ia distance measurements. The Nancy Grace Roman Space Telescope is uniquely sensitive to this measurement as it can discover high redshift SNe Ia and measure them with high precision. We present a methodology for reconstructing the probability distribution of the weak lensing magnification $\mu$ of SNe Ia, $p(\mu )$, from observational data, and using it to constrain cosmological parameters. We find that the reconstructed $p(\mu )$ can be fitted accurately by a stretched Gaussian distribution and used to measure the variance of $\mu$, ${\xi }_{\mu }$, which can be compared to theoretical predictions in a likelihood analysis. Applying our methodology to a set of realistically simulated SNe Ia expected from the Roman Space Telescope, we find that using the weak lensing magnification of the SNe Ia constrains a combination of matter density ${\mathrm{\Omega }}_m$ and matter clustering amplitude ${\sigma }_8$. SN Ia distances alone lead to a better than 1% measurement of ${\mathrm{\Omega }}_m$. The combination of SN Ia weak lensing magnification and distance measurements result in a $\sim 10\%$ measurement on ${\sigma }_8$. The SNe Ia from Roman will be powerful in constraining the cosmological model.

We study a semilocal Abelian Higgs sigma model with ${\mathbb{CP}}^2$-valued scalar fields coupled to gravity. We establish the conditions needed for self-duality in this system and obtain cosmic strings, both of self-dual character and out of the self-dual point, in the reference chart of ${\mathbb{CP}}^2$. In any of the other two charts of a minimum atlas, the transition functions break the global $SU(2)$ symmetry to the Abelian subgroup $e^{i{\sigma }^3\alpha }$. In this context, using the transition functions, a new self-dual structure can be constructed, which defines a second species of cosmic strings. Because of the presence of a potential energy for the scalar fields, each species takes values in a different bounded region of the target space and is most naturally described using a particular chart of ${\mathbb{CP}}^2$.

We present a simple extension of the Standard Model that leads to renormalizable long-range vector-mediated neutrino self-interactions. This model can resolve the Hubble tension by delaying the onset of neutrino free-streaming during recombination, without conflicting with other measurements. The extended gauge, scalar, and neutrino sectors lead to observable signatures, including invisible Higgs and $Z$ decays, thereby relating the Hubble tension to precision measurements at the LHC and future colliders. The model has a new neutrinophilic gauge boson with $m_{Z^{\prime }}\sim \mathcal{O}(10\mathrm{eV})$ and charged Higgses at a few 100 GeV. It requires hidden neutrinos with active-hidden mixing angles larger than $5\times {10}^{-4}$ and masses in the range $1÷300\mathrm{eV}$, which could also play a role for short baseline neutrino oscillation anomalies.

We propose a novel method in that quark-gluon tagging of the jets emitted as initial state radiation (ISR) can boost searches of invisible Higgs bosons from gluon fusion processes against irreducible electroweak vector boson productions. While quark ISR typically takes up a dominant portion than gluon in the background processes mainly by frequent quark-gluon-initiated hard scatterings at the LHC, the gluon ISR portion in the gluon fusion can be significantly larger in the central region of the detector. Focusing on invisible Higgs boson searches using jet substructure variables capturing the new features, we demonstrate that the Higgs boson from gluon fusion constrains invisible Higgs boson decays the most, over vector boson fusion traditionally known as the most constraining, and the limit on the branching ratio is significantly improved. We summarize with emphasizing that our method has wider implications in the search for new resonances from gluon fusion processes.

In a recent work [J. Lenz et al., Phys. Rev. D 101, 094512 (2020)] we studied the phase structure of the Gross-Neveu (GN) model in $1+1$ dimensions at finite number of fermion flavors $N_{\mathrm{f}}=2,8,16$, finite temperature and finite chemical potential using lattice field theory. Most importantly, we found an inhomogeneous phase at low temperature and large chemical potential, quite similar to the analytically solvable $N_{\mathrm{f}}\to \infty$ limit. In the present work we continue our lattice field theory investigation of the finite-$N_{\mathrm{f}}$ GN model by studying the formation of baryons, their spatial distribution and their relation to the chiral condensate. As a preparatory step we also discuss a linear coupling of lattice fermions to the chemical potential.

We propose a novel method to calculate the meson mass in the framework of Dyson-Schwinger equation and Bethe-Salpeter equation (BSE), once their dominant interactions are identified. The method is based on the perturbation theory of matrix, which is widely used in quantum mechanics. Taking interactions other than the dominant ones as perturbations, we derive the first order correction of quark propagator. Implementing the perturbation on BSE, the mass correction at first order is then given. We exemplify this method with the well-known rainbow-ladder (RL) truncation, and go beyond the RL using a simple model, i.e., the Munczek-Nemirovsky (MN) model, by studying the pion and $\rho$ mesons mass shift. The results are all in good agreement with those obtained by fully solving the BSE beyond RL. Our perturbative method therefore can be used to give a semiquantitative estimate of meson mass correction in cases when the BSEs are complicated by interactions that go beyond the dominant one.

We use a diffusion Monte Carlo method to solve the many-body Schrödinger equation describing fully heavy tetraquark systems. This approach allows us to reduce the uncertainty of the numerical calculation at the percent level, accounts for multiparticle correlations in the physical observables, and avoids the usual quark clustering assumed in other theoretical techniques applied to the same problem. The interaction between particles was modeled by the most general and accepted potential—i.e., a pairwise interaction including Coulomb, linear-confining and hyperfine spin-spin terms. This means that, in principle, our analysis should provide some rigorous statements about the mass location of the all-heavy tetraquark ground states, which is particularly timely due to the very recent observation made by the LHCb Collaboration of some enhancements in the invariant mass spectra of $J/\psi$ pairs. Our main results are as follows: (i) The $cc\overline{c}\overline{c}$, $cc\overline{b}\overline{b}$ ($bb\overline{c}\overline{c}$), and $bb\overline{b}\overline{b}$ lowest-lying states are located well above their corresponding meson-meson thresholds. (ii) The $J^{PC}=0^{++}cc\overline{c}\overline{c}$ ground state with preferred quark-antiquark pair configurations is compatible with the enhancement(s) observed by the LHCb Collaboration. (iii) Our results for the $cc\overline{c}\overline{b}$ and $bb\overline{c}\overline{b}$ sectors seem to indicate that the $0^{+}$ and $1^{+}$ ground states are almost degenerate, with the $2^{+}$ located around 100 MeV above them. (iv) Smaller mass splittings for the $cb\overline{c}\overline{b}$ system are predicted, with absolute mass values in reasonable agreement with other theoretical works. (v) The $1^{++}$ $cb\overline{c}\overline{b}$ tetraquark ground state lies at its lowest $S$-wave meson-meson threshold, and it is compatible with a molecular configuration.

Magnetic field effect on the pion superfluid phase transition is investigated in the frame of a Pauli–Villars regularized Nambu–Jona-Lasinio model. Instead of directly dealing with a charged pion condensate, we apply Goldstone’s theorem (massless Goldstone boson ${\pi }^{+}$) to determine the onset of the pion superfluid phase and obtain the phase diagram in the magnetic field, temperature, isospin, and baryon chemical potential space. In a weak magnetic field, it is analytically proven that the critical isospin chemical potential of the pion superfluid phase transition is equal to the mass of ${\pi }^{+}$ meson in the magnetic field. The pion superfluid phase is retarded to higher isospin chemical potential and can survive at a higher temperature and higher baryon chemical potential under the external magnetic field.

A comprehensive study of the application of $\mathrm{SO}(D+1)$ coherent states of Perelomov type to loop quantum gravity in general spacetime dimensions $1+D\ge 3$ is given in this paper. We focus on so-called simple representations of $\mathrm{SO}(D+1)$ which solve the simplicity constraint acting on edges and the associated homogeneous harmonic function spaces. With the harmonic function formulation, we study general properties of the coherent states such as the peakedness properties and the inner product. We also discuss the properties of geometric operators evaluated in the coherent states. In particular, we calculate the expectation value of the volume operator, and the results agree with the ones obtained from the classical label of the coherent states up to error terms which vanish in the limit of large representation labels $N$, i.e., the analogue of the large spin limit in standard ($1+3$)-dimensional loop quantum gravity.

We investigate the dynamical Casimir effect for a one-dimensional resonant cavity, with one oscillating mirror. Specifically, we study the discrete spectrum of created particles in a region of frequencies above the oscillation frequency ${\omega }_0$ of the mirror. We focus our investigation on an oscillation time equal to $2L_0/c$, where $L_0$ is the initial and final length of the cavity, and $c$ is the speed of light. For this oscillation duration, a field mode, after being perturbed by the moving mirror, never meets this mirror in motion again, which allows us to exclude this effect of reinteraction on the particle creation process. Then, we describe the creation of particles with energies above $\hslash {\omega }_0$, due only to the relativistic aspect of the mirror’s velocity (and these particles form what we call relativistic bands). Thus, we analyze the formation of these relativistic bands in a discrete spectrum of created particles.

In this paper, we study the small-large black hole phase transition and construct the Ruppeiner geometry for the five-dimensional charged Gauss-Bonnet-AdS black hole in the grand canonical ensemble. By making use of the equal area law, we obtain the analytical coexistence curve of the small and large black holes. Then the phase diagrams are examined. We also calculate the change of the thermodynamic volume during the small-large phase transition, which indicates that there exists a sudden change among the black hole microstructures. The corresponding normalized scalar curvature of the Ruppeiner geometry is also calculated. Combing with the empirical observation of scalar curvature, we find that for low electric potential, the attractive interaction dominates among the microstructures, while a high electric potential produces repulsive interactions. In the reduced parameter space, we observe that only attractive interaction is allowed when the coexistence region is excluded. The normalized scalar curvature also admits a critical exponent 2 and a universal constant $-\frac{1}{8}$. In particular, the value of the normalized scalar curvature keeps the same along the coexistence small and large black hole curves. So in the grand canonical ensemble, the interaction can keep constant at the phase transition where the black hole microstructures change. These results disclose the intriguing microstructures for the charged AdS black hole in the Gauss-Bonnet gravity.

In order to describe magnetogenesis during inflation in the kinetic coupling model, we utilize a gradient expansion which is based on the fact that only long-wavelength (superhorizon) modes undergo amplification. For this purpose, we introduce a set of functions (bilinear combinations of electromagnetic fields with an arbitrary number of spatial curls) satisfying an infinite chain of equations. Apart from the usual mode enhancement due to interaction with the inflaton, these equations also take into account the fact that the number of relevant modes constantly grows during inflation. Truncating this chain, we show that even with a relatively small number of equations, it is possible to describe the electric and magnetic energy densities with a few percent accuracy during the whole inflation stage. We arrive at this conclusion for different types of coupling functions (increasing, decreasing, and nonmonotonic) in the regime with strong backreaction and its absence.

It is common to express cosmological measurements in units of $h^{-1}\mathrm{Mpc}$. Here, we review some of the complications that originate from this practice. A crucial problem caused by these units is related to the normalization of the matter power spectrum, which is commonly characterized in terms of the linear-theory rms mass fluctuation in spheres of radius $8h^{-1}\mathrm{Mpc}$, ${\sigma }_8$. This parameter does not correctly capture the impact of $h$ on the amplitude of density fluctuations. We show that the use of ${\sigma }_8$ has caused critical misconceptions for both the so-called ${\sigma }_8$ tension regarding the consistency between low-redshift probes and cosmic microwave background data and the way in which growth-rate estimates inferred from redshift-space distortions are commonly expressed. We propose to abandon the use of $h^{-1}\mathrm{Mpc}$ units in cosmology and to characterize the amplitude of the matter power spectrum in terms of ${\sigma }_{12}$, defined as the mass fluctuation in spheres of radius 12 Mpc, whose value is similar to the standard ${\sigma }_8$ for $h\sim 0.67$.

This paper is an extension of the paper by Del Popolo et al. [Phys. Rev. D 101, 083505 (2020)] to take account of the effect of dynamical friction. We show how dynamical friction changes the threshold of collapse ${\delta }_c$ and the turnaround radius $R_t$. We numerically determine the relationship between the turnaround radius $R_{\mathrm{t}}$ and mass $M_{\mathrm{t}}$ in $\mathrm{\Lambda }\mathrm{CDM}$, dark energy scenarios, and an $f(R)$ modified gravity model. Dynamical friction gives rise to a $R_{\mathrm{t}}\text{−}{M}_{\mathrm{t}}$ relation differing from that of the standard spherical collapse. In particular, dynamical friction amplifies the effects of shear and vorticity already studied by Del Popolo et al. A comparison of the $R_{\mathrm{t}}\text{−}{M}_{\mathrm{t}}$ relationships for $\mathrm{\Lambda }\mathrm{CDM}$, dark energy, and modified gravity models shows that the $R_{\mathrm{t}}\text{−}{M}_{\mathrm{t}}$ relationship of $\mathrm{\Lambda }\mathrm{CDM}$ is similar to that of the dark energy models, and small differences are seen when comparing with the $f(R)$ models. The effects of shear, rotation, and dynamical friction are particularly evident at galactic scales, giving rise to a difference between the $R_{\mathrm{t}}\text{−}{M}_{\mathrm{t}}$ relation of the standard spherical collapse of the order of $\simeq 60\%$. Finally, we show how the new values of the $R_{\mathrm{t}}\text{−}{M}_{\mathrm{t}}$ relation influence the constraints on the $w$ parameter of the equation of state.

Recent measurements of neutron star mass from several candidates (PSR $\mathrm{J}1614-2230$, PSR $\mathrm{J}0348+0432$, MSP $\mathrm{J}0740+6620$) set the lower bound on the maximum possible mass for this class of compact objects $\sim 2{\mathrm{M}}_{\odot }$. Existence of stars with high mass brings the possibility of existence of exotic matter (hyperons, meson condensates) at the core region of the objects. In this work, we investigate the (anti)kaon ($K^{-}$, ${\overline{K}}^0$) condensation in $\beta$-equilibrated nuclear matter within the framework of covariant density functional theory. The functionals in the kaonic sector are constrained by the experimental studies on $K^{-}$ atomic, kaon-nucleon scattering data fits. We find that the equation of state softens with the inclusion of (anti)kaon condensates, which lowers the maximum mass of neutron star. In one of the density-independent coupling cases, the $K^{-}$ condensation is through a first order phase transition type, which produces a $2{\mathrm{M}}_{\odot }$ neutron star. The first order phase transition results in mixed phase region in the inner core of the stars. While ${\overline{K}}^0$ condensation appears via second-order phase transition for all the models we consider here.

We report here an extension of the measurement of the all-particle cosmic-ray spectrum with IceTop to lower energy. The new measurement gives full coverage of the knee region of the spectrum and reduces the gap in energy between previous IceTop and direct measurements. With a new trigger that selects events in closely spaced detectors in the center of the array, the IceTop energy threshold is lowered by almost an order of magnitude below its previous threshold of 2 PeV. In this paper we explain how the new trigger is implemented, and we describe the new machine-learning method developed to deal with events with very few detectors hit. We compare the results with previous measurements by IceTop and others that overlap at higher energy and with HAWC and Tibet in the 100 TeV range.

QED perturbation theory in a background field has been conjectured to break down for sufficiently high field intensity. The high-intensity behavior of a field theory is however intertwined with its high-energy (UV) behavior. Here we show that a UV modification of QED changes the high-intensity behavior of observables. Specifically we study nonlinear Compton scattering in a constant crossed field in QED with an additional Pauli term. In the UV modified theory the cross section exhibits a faster power-law scaling with intensity than in ordinary QED.

Using the soft pion theorem, crossing, and the dispersion relations for the two-pion distribution amplitude (DA), we argue that the second Gegenbauer moment, the $\rho$-meson DA ($a_2^{(\rho )}$), is most probably negative. This result is at variance with the majority of the model calculations for $a_2^{(\rho )}$. Using the instanton theory of the QCD vacuum, we computed $a_2^{(\rho )}$ at a low normalization point and obtain for the ratio $a_2^{(\rho )}/M_3^{(\pi )}$ a definitely negative value in the range of $a_2^{(\rho )}/M_3^{(\pi )}\in [-2,-1]$. The range of values corresponds to a generous variation of the parameters of the instanton vacuum. The value of the second Gegenbauer moment of pion DA is positive in the whole range and is compatible with its the most advanced lattice measurement. It seems that the topologically nontrivial field configurations in the QCD vacuum (instantons) lead to qualitatively different shapes of the pion and the $\rho$-meson DAs.