In this paper, we compare the scalar field dynamics in the axionlike and power law potentials for both positive and negative values of the exponents. We find that, for positive exponents, both potentials exhibit similar scalar field dynamics, and it can be difficult to distinguish them at least at the background level. Even though the potentials are oscillatory in nature, for positive exponents scaling solutions can be achieved for larger values of the exponent for which the dynamics can be different during early times. Because of the presence of this scaling nature, there is a turnaround in the values of the scalar field equation of state as we increase the values of the exponent in both potentials. This indicates the deviation from the oscillatory behavior for the larger values of the exponent. For negative values of the exponent, the dynamics of the scalar field is distinguishable, and axionlike potential can give rise to cosmologically viable tracker solutions unlike the power law potentials. For negative values of the exponent, the axionlike potential can behave like a cosmological constant around its minima, and the dark energy scale can be related to the potential scale. Because of the cosmological-constant-like behavior of the axionlike potential for negative exponent around its minima, the late time dynamics can be similar to Lambda cold dark matter $(\mathrm{\Lambda }\mathrm{CDM})$, and we get a similar observational constraint on the parameters for both $\mathrm{\Lambda }\mathrm{CDM}$ and the axionlike potential with a negative exponent. So, while for positive exponents we may not distinguish the two potentials, for negative exponents the dynamics of the scalar field is distinguishable.

The recent start of the fourth observing run of the LIGO-Virgo-KAGRA (LVK) Collaboration has reopened the hunt for gravitational-wave (GW) signals, with one compact-binary-coalescence (CBC) signal expected to be observed every few days. Among the signals that could be detected for the first time there is the stochastic gravitational-wave background (SGWB) from the superposition of unresolvable GW signals that cannot be detected individually. In fact, multiple SGWBs are likely to arise given the variety of sources, making it crucial to identify the dominant components and assess their origin. However, most search methods with ground-based detectors assume the presence of one SGWB component at a time, which could lead to biased results in estimating its spectral shape if multiple SGWBs exist. Therefore, a joint estimate of the components is necessary. In this work, we adapt such an approach and analyze the data from the first three LVK observing runs, searching for a multicomponent isotropic SGWB. We do not find evidence for any SGWB and establish upper limits on the dimensionless energy parameter ${\mathrm{\Omega }}_{\mathrm{gw}}(f)$ at 25 Hz for five different power-law spectral indices, $\alpha =0,2/3$, 2, 3, 4, jointly. For the spectral indices $\alpha =2/3$, 2, 4, corresponding to astrophysical SGWBs from CBCs, r-mode instabilities in young rotating neutron stars, and magnetars, we draw further astrophysical implications by constraining the ensemble parameters $K_{\mathrm{CBC}},K_{\mathrm{r}-\text{modes}},K_{\text{magnetars}}$, defined in the main text.

Pulsar timing arrays (PTAs) use an array of millisecond pulsars to search for gravitational waves in the nanohertz regime in pulse time of arrival data. This paper presents rigorous tests of PTA methods, examining their consistency across the relevant parameter space. We discuss updates to the 15-year isotropic gravitational-wave background analyses and their corresponding code representations. Descriptions of the internal structure of the flagship algorithms enterprise and ptmcmcsampler are given to facilitate understanding of the PTA likelihood structure, how models are built, and what methods are currently used in sampling the high-dimensional PTA parameter space. We introduce a novel version of the PTA likelihood that uses a two-step marginalization procedure that performs much faster in gravitational wave searches, reducing the required resources facilitating the computation of Bayes factors via thermodynamic integration and sampling a large number of realizations for computing Bayesian false-alarm probabilities. We perform stringent tests of consistency and correctness of the Bayesian and frequentist analysis methods. For the Bayesian analysis, we test prior recovery, simulation recovery, and Bayes factors. For the frequentist analysis, we test that the optimal statistic, when modified to account for a non-negligible gravitational-wave background, accurately recovers the amplitude of the background. We also summarize recent advances and tests performed on the optimal statistic in the literature from both gravitational wave background detection and parameter estimation perspectives. The tests presented here validate current analyses of PTA data.

This study measured the ${}^{10}\mathrm{Be}$ and ${}^{26}\mathrm{Al}$ production cross sections of muon-induced long-lived radionuclides to investigate the long-term variations in high-energy cosmic ray muon yields and high-energy galactic cosmic rays over a few million years. We exposed targets consisting of synthetic silica plates and quartz samples in a 1-m-long granite core to a beam containing $8.79\times {10}^{12}$ positive muons over $\sim 120\mathrm{days}$ with an energy of 160 GeV extracted at the COMPASS experiment line at CERN-SPS. The experiment revealed the ${}^{10}\mathrm{Be}$ and ${}^{26}\mathrm{Al}$ production rates in the synthetic silica plates as $(1.8\pm 0.1)\times {10}^{-7}$ and $(1.3\pm 0.08)\times {10}^{-6}\text{atoms}/\mathrm{muon}/({\mathrm{g}}_{\mathrm{SiO}2}/{\mathrm{cm}}^2)$, respectively. In addition, we obtained the production rates in the granite core as approximately $(4.1\pm 0.2)\times {10}^{-7}$ and $(4.0\pm 0.3)\times {10}^{-6}\mathrm{atoms}/\mathrm{muon}/({\mathrm{g}}_{\text{quartz}}/{\text{cm}}^2)$ for ${}^{10}\mathrm{Be}$ and ${}^{26}\mathrm{Al}$, respectively, although those rates varied with location. Furthermore, we performed full muon exposure simulations for the identical experimental setup using two simulators, phits and fluka, to examine the ${}^{10}\mathrm{Be}$ and ${}^{26}\mathrm{Al}$ production rates obtained in the muon beam experiment. The experimental rates are approximately 2–3 times higher than the simulated ones. Although the simulations are complex and depend on many models. Additionally, the phits and fluka analysis of the particle contributions to the ${}^{10}\mathrm{Be}$ and ${}^{26}\mathrm{Al}$ production rates indicated that the positive muons and secondary particles produce those nuclides at a constant rate and an increasing rate with respect to granite core location, respectively, suggesting direct muon-induced spallation and secondary particle-induced spallation. The experimental production ratio ${}^{26}\mathrm{A}\mathrm{l}/{}^{10}\mathrm{B}\mathrm{e}$ also exhibited characteristics of both spallation types. We conclude that the production cross sections of ${}^{10}\mathrm{Be}$ and ${}^{26}\mathrm{Al}$ for the target atoms of oxygen and silicon were $9.2\pm 0.6\mathrm{\mu }\mathrm{b}$ and $132.3\pm 7.7\mathrm{\mu }\mathrm{b}$ via direct muon-induced spallation in the synthetic silica, and $27.2\pm 1.9\mathrm{\mu }\mathrm{b}$ and $486\pm 44\mathrm{\mu }\mathrm{b}$ including secondary particle-induced spallation in the granite quartz, respectively. Additionally, the depth profiles of ${}^{10}\mathrm{Be}$ and ${}^{26}\mathrm{Al}$ concentrations in rocks estimated from the known total muon flux deep underground and this study’s cross sections were comparable to those of the concentrations measured at depths greater than $5000{\mathrm{g}/\mathrm{cm}}^2$. Overall, our study showed that these cross sections revealed by the high-energy muon beam experiment are a valuable tool for estimating variations in high-energy galactic cosmic rays over a few million years using in situ rocks and simulators.

We study the effect of isospin-symmetry breaking in the framework of the extended linear $\sigma$ model in vacuum. In this model, several particles mix with each other at tree level, due to the three nonzero scalar condensates (nonstrange, strange, isospin). We resolve these mixings with the help of various field transformations. We compute all possible meson mixings and decay widths at tree level and perform a ${\chi }^2$ fit to PDG data. A very good fit is found if we exclude the (very small $\sim 130\mathrm{keV}$) $\omega \to \pi \pi$ decay. We also investigate the violation of Dashen’s theorem.

The hadron mass can be obtained through the calculation of the trace of the energy-momentum tensor in the hadron which includes the trace anomaly and sigma terms. The anomaly due to conformal symmetry breaking is believed to be an important ingredient for hadron mass generation and confinement. In this work, we will present the calculation of the glue part of the trace anomaly form factors of the pion up to $Q^2\sim 4.3{\mathrm{GeV}}^2$ and the nucleon up to $Q^2\sim 1{\mathrm{GeV}}^2$. The calculations are performed on a domain wall fermion ensemble with overlap valence quarks at seven valence pion masses varying from $\sim 250$ to $\sim 540\mathrm{MeV}$, including the unitary point $\sim 340\mathrm{MeV}$. We calculate the radius of the glue trace anomaly for the pion and the nucleon from the $z$ expansion. By performing a two-dimensional Fourier transform on the glue trace anomaly form factors in the infinite momentum frame with no energy transfer, we also obtain their spatial distributions for several valence quark masses. The results are qualitatively extrapolated to the physical valence pion mass with systematic errors from the unphysical sea quark mass, discretization effects in the renormalization sum rule, and finite-volume effects to be addressed in the future. We find the pion’s form factor changes sign, as does its spatial distribution, for light quark masses. This explains how the trace anomaly contribution to the pion mass approaches zero toward the chiral limit.

We explore the ’t Hooft-Veneziano limit of the Polyakov loop models at finite baryon chemical potential. Using methods developed by us earlier we calculate the two- and $N$-point correlation functions of the Polyakov loops. This gives a possibility to compute the various potentials in the confinement phase and to derive the screening masses outside the confinement region. In particular, we establish the existence of complex masses and an oscillating decay of correlations in a certain range of parameters. Furthermore, it is shown that the calculation of the $N$-point correlation function in the confinement phase reduces to the geometric median problem. This leads to a large $N$ analog of the $Y$ law for the baryon potential.

A model of light hybrid mesons and their strong decays is developed. The model employs a gluonic quasiparticle to describe low energy gluodynamics and uses the QCD Hamiltonian in Coulomb gauge to guide the construction of states and decay amplitudes. We compute the partial widths of the twelve low lying isovector and vector hybrids. Implications of these results on hybrid searches are also made, with the chief conclusions being that direct observation of the vector states will be difficult, that a hybrid $\pi (1800)$ has distinctive decay characteristics, a narrow $\eta (1900)$ hybrid should exist, an ${\eta }_1(1750)$ should be sought, and that the exotic nature of $J^{PC}=2^{-+}$ hybrid mesons should be discernible with sufficient data. We argue that the isovector ${\pi }_2$ hybrid has been discovered, giving a total of four possible hybrid mesons, ${\pi }_1(1600)$, ${\eta }_1(1855)$, $\pi (1800)$, and ${\pi }_2(2360)$, which appear to be filling out the low lying hybrid supermultiplet in the expected fashion.

Following the first science results of the LUX-ZEPLIN (LZ) experiment, a dual-phase xenon time projection chamber operating from the Sanford Underground Research Facility in Lead, South Dakota, USA, we report the initial limits on a model-independent nonrelativistic effective field theory describing the complete set of possible interactions of a weakly interacting massive particle (WIMP) with a nucleon. These results utilize the same 5.5 t fiducial mass and 60 live days of exposure collected for the LZ spin-independent and spin-dependent analyses while extending the upper limit of the energy region of interest by a factor of 7.5 to 270 keV. No significant excess in this high energy region is observed. Using a profile-likelihood ratio analysis, we report 90% confidence level exclusion limits on the coupling of each individual nonrelativistic WIMP-nucleon operator for both elastic and inelastic interactions in the isoscalar and isovector bases.

Recently, there has been a growing interest in investigating homogeneous but anisotropic spacetimes owing to their relation with nonrotating, uncharged black hole interiors. We present a description of axial perturbations for a massless scalar field minimally coupled to this geometry. We truncate the action at the quadratic perturbative order and tailor our analysis to compact spatial sections. Perturbations are described in terms of perturbative gauge invariants, linear perturbative constraints, and their canonically conjugate variables. The entire set, encompassing perturbations and homogeneous degrees of freedom, is consolidated into a canonical one. We employ a hybrid approach to quantize this system, integrating a quantum representation of the homogeneous sector using loop quantum cosmology techniques with a conventional field quantization of the perturbations.

In this paper we study the multipole expansion of the long-wavelength effective action for radiative sources in ($d+1$) spacetime dimensions. We present detailed expressions for the multipole moments for the case of scalar-, electromagnetic-, and (linearized) gravitational-wave emission. For electromagnetism and gravity, we derive expressions for the odd-parity, magnetic-type moments as SO($d$) duals of the ones traditionally used in the literature. The $d$-dimensional case features a novel set of “Weyl-type” moments, coupling to the spatial part of the Weyl tensor, which are absent in three dimensions. Agreement is found in the overlap with previous known results, notably in the $d\to 3$ limit. Because of its reliance on dimensional regularization, the results presented here play a crucial role for the further development of the effective field theory approach to gravitational dynamics, and in particular for the computation of the gravitational-wave flux, starting at the third post-Newtonian order.

Unimodular gravity is a compelling modified theory of gravity that offers a natural solution to the cosmological constant problem. However, for unimodular gravity to be considered a viable theory of gravity, one has to show that it has a well-posed initial value formulation. Working in vacuum, we apply Dirac’s algorithm to find all the constraints of the theory. Then, we prove that, for initial data compatible with these constraints, the evolution is well-posed. Finally, we find sufficient conditions for a matter action to preserve the well-posedness of the initial value problem of unimodular gravity. As a corollary, we argue that the “unimodular” restriction on the spacetime volume element can be satisfied by a suitable choice of the lapse function.

We analyze the scalar radiation emitted by a source interacting with a nonminimally coupled scalar field in four-dimensional Schwarzschild–de Sitter spacetime. We obtain the emission probability using quantum field theory in curved spacetimes at tree level. We find that the source emits synchrotron-type radiation for orbits near the photon sphere for all allowed values of the parameters. We also find that the emitted power strongly depends on the coupling to the curvature scalar. In particular, the previously observed enhancement in the contribution of lower multipoles to the emitted power in this spacetime with minimal coupling is absent when conformal coupling is considered.

This paper explores the evolution of the overdense region of dark matter in the presence of a nonminimally coupled scalar field which is used to model quintessence and phantomlike dark energy. We focus on algebraic coupling, where the interaction Lagrangian is independent of the derivatives of the scalar field. To make our model more relativistic, like the minimal coupling scenario we studied earlier, we consider a spacetime structure that is internally closed Friedmann-Lemaître-Robertson-Walker (FLRW) spacetime and externally the generalized Vaidya spacetime. This structure allows nonzero matter flux at the boundary of the overdense region. Our investigation reveals that an increment of the coupling strength causes dark energy to cluster with dark matter at a certain cosmological scale where the influence of dark energy cannot be ignored. This phenomenon arises from the specific nature of the nonminimal coupling considered in this paper. While the evolution of matter’s energy density remains unchanged, the scalar field’s Klein-Gordon equation is modified, causing dark energy to deviate from its homogeneous state and cluster with dark matter. Similar to minimal coupling scenarios, closed spherical regions do not collapse within certain parameter ranges, exhibiting eternal expansion within the spatially flat FLRW spacetime and acting as voids with decreasing matter density. The study extends our understanding of the cosmological scenarios where the virialization of the overdense regions of dark matter is influenced by the nonminimally coupled dark energy.

We study the constraint of the nonsupersymmetric (non-SUSY) anti–de Sitter (AdS) conjecture on the three-dimensional vacua obtained from the compactification of the Standard Model coupled to Einstein gravity on a circle where the three-dimensional components of the four-dimensional metric are general functions of both noncompact and compact coordinates. We find from studying the wave function profile of the three-dimensional metric in the compactified dimension that the radius of the compactified dimension must be quantized. Consequently, the three-dimensional vacua are constrained by not only the non-SUSY AdS conjecture but also the quantization rule of the circle radius, leading to both upper and lower bounds for the mass of the lightest neutrino as $\sqrt{2}\le m_{\nu }/\sqrt{{\mathrm{\Lambda }}_4}<\sqrt{3}$, where ${\mathrm{\Lambda }}_4\simeq 5.06\times {10}^{-84}{\mathrm{GeV}}^2$ is the observed cosmological constant. This means that the lightest neutrino should have a mass around ${10}^{-32}\mathrm{eV}$ or it would be approximately massless. With this prediction, we reconstruct the light neutrino mass matrix that is fixed by the neutrino oscillation data and in terms of three new mixing angles and six new phases for both the normal ordering and inverted ordering. In the situation where the light neutrino mass matrix is Hermitian, we calculate its numerical value in the $3\sigma$ range.

Thermal freeze-out offers an attractive explanation of the dark matter density free from fine-tuning of initial conditions. For dark matter with a mass below tens of MeV, photons, electrons, and neutrinos are the only available direct Standard Model annihilation products. Using a full three-sector abundance calculation, we determine the minimal mass of dark matter, allowing for an arbitrary branching into electrons/photons and neutrinos that is compatible with current cosmological observations. The analysis takes into account the heat transfer between the various sectors from annihilation and elastic scattering, representing the first fully self-consistent analysis that tracks the respective sectors’ temperatures. We thereby provide accurate thermal annihilation cross sections, particularly for velocity-dependent cases, and deduce the sensitivity of current and upcoming CMB experiments to MeV thermal dark matter. In the latter context, we also establish the fine-tuned parameter region where a tiny admixture of neutrinos in the final states rules in MeV-scale $p$-wave annihilating DM into electrons. Finally, we show that a sub-% millicharged dark matter with an interaction strength that interferes with 21-cm cosmology is still allowed when freeze-out is supplemented with annihilation into neutrinos. For all cases considered, we provide concrete particle physics models and supplement our findings with a discussion of other relevant experimental results.

We argue that the lensing power spectrum of astrometric shift (lensing shift power spectrum) is a powerful tool for probing the clustering property of dark matter on subgalactic scales. First we give the formalism to probe the nature of dark matter by using the lensing shift power spectrum. Then, leveraging recent measurements of the lensing shift power spectrum on an angular scale of approximately 1 arcsec toward the gravitationally lensed quasar MG $\mathrm{J}0414+0534$ at the redshift of $z_S=2.639$, we place constraints on the mass of warm dark matter (WDM) particles $m_{\mathrm{WDM}}$ and their fraction in a mixed dark matter (MDM) model $r_{\mathrm{WDM}}$, in which WDM and cold dark matter coexist. Although the constraint derived from the above single lensing system is not as strong as the existing constraints, as we show in this paper, the lensing shift power spectrum has a great potential to obtain much tighter constraints on WDM and MDM models through future observations, highlighting the importance of well-controlled systematic error considerations for achieving enhanced precision.

In core-collapse supernovae, the neutrino density is so large that neutrino flavor instabilities, leading to flavor conversion, can be triggered by the forward scattering of neutrinos among each other, if a crossing between the angular distributions of electron neutrinos and antineutrinos exists (fast instability in the limit of vanishing vacuum frequency) or in the presence of perturbations induced by the neutrino vacuum frequency (slow instability). Recently, the conjecture has been advanced that neutrino collisions with the medium could be another mean to kick start flavor change (collisional instability). Inspired by a spherically symmetric core-collapse supernova model with mass $18.6M_{\odot }$, we compute the neutrino angular distributions solving the kinetic equations for an average energy mode and investigate the occurrence of flavor instabilities at different postbounce times, ranging from the accretion phase to the early cooling phase. We find that fast and slow flavor instabilities largely dominate over the collisional ones in the decoupling region for all postbounce times. While more work is needed to assess the relevance of collisional instabilities in neutrino-dense environments, our findings suggest that neutrino collisions with matter affect the flavor evolution in the decoupling region but are not responsible for triggering flavor conversion, if crossings in the neutrino lepton number angular distribution exist.

We consider dark matter velocity distributions with an anisotropic component, and analyze how the velocity structure can be probed in a solid-state ionization detector with no directional detection capability using a daily modulation effect due to the anisotropic response function of the target. We show that with an energy resolution of $<10\mathrm{eV}$ it is possible to identify the presence of an anisotropic component consistent with observations for sub-GeV dark matter, and that introduction of daily modulation information substantially improves the sensitivity in a narrow mass range.

The definitions of the quark and gluon transversity generalized parton distributions (GPDs) in spin-$3/2$ particles are obtained in the light-cone gauge. It is found that they contain 16 independent components for each parton. Their even or odd property is found in terms of a skewness variable, and the odd transversity GPDs vanish in the forward limit. There are 16 amplitudes with helicity flip of quark or gluon. We conclude that all the amplitudes, unpolarized, polarized, and transversity amplitudes, have a common factor $F(\zeta )$ carrying all the complex parts. Here, the variable $\zeta$ is the helicity difference $\zeta =({\lambda }^{\prime }-\lambda )-({\mu }^{\prime }-\mu )$ for the amplitude ${\mathcal{A}}_{{\lambda }^{\prime }{\mu }^{\prime },\lambda \mu }$. This kinematical factor is associated with the transfer of the orbital angular momentum in the quark- and gluon-spin-$3/2$ particle scattering amplitudes. We also derive another main physical quantity, transversity distribution, from the transversity GPDs in the forward limit for the spin-$3/2$ particles.