The parameter ${\sigma }_8$, which represents the root-mean-square (rms) mass fluctuations on a scale of $R_8=8h^{-1}\mathrm{Mpc}$ (where $h$ is the reduced Hubble parameter), is commonly used to quantify the amplitude of matter fluctuations at linear cosmological scales. However, the dependence of $R_8$ on $h$ complicates direct comparisons of ${\sigma }_8$ values obtained under different assumptions about $H_0$, since ${\sigma }_8$ in such cases characterizes the amount of structure at different physical scales. This issue arises both when comparing ${\sigma }_8$ values from fitting analyses of cosmological models with differing $H_0$ posteriors and when contrasting constraints from galaxy clustering experiments that employ different priors on the Hubble parameter. As first noted by Sánchez in [Phys. Rev. D 102, 123511 (2020)], quantifying the growth tension using ${\sigma }_8$ can introduce substantial biases and couple the growth and Hubble tensions in an intricate and uncontrolled way. To address these challenges, Sánchez proposed an alternative parameter, ${\sigma }_{12}$, defined as the rms mass fluctuations at a scale of 12 Mpc, which is independent of $h$. Although Sánchez’s work was published five years ago and other authors have since highlighted the limitations of ${\sigma }_8$, much of the cosmological community—including large collaborations—continues to rely on this parameter rather than adopting ${\sigma }_{12}$, seemingly due only to historical considerations. In this work, we illustrate the biases introduced by the use of ${\sigma }_8$ through some clear examples, aiming to motivate the community to transition from ${\sigma }_8$ to ${\sigma }_{12}$. We show that the bias found in models with large values of $H_0$ is more prominent. This artificially complicates the search for a model that can efficiently resolve the Hubble tension without exacerbating the growth tension inferred from galaxy clustering measurements. We argue that the worsening of the growth tension in these models is much less pronounced than previously thought or may even be nonexistent.

In 1998 Carlip [Nucl. Phys. B, Proc. Suppl. 88, 10 (2000)] and Solodukhin [Phys. Lett. B 454, 213 (1999)] independently conjectured the equality between fluctuations in the modular Hamiltonian of black holes and its expectation value. Banks and Zurek’s 2021 work [T. Banks and K. M. Zurek, Phys. Rev. D 104, 126026 (2021)] generalized this observation to any causal diamonds. We use this observation to calculate the precise normalization of primordial scalar and tensor power spectra in the holographic space-time model of inflation. In previous work [T. Banks and W. Fischler, arXiv:1501.01686.] Banks and Fischler outlined the general calculation of inflationary power spectra in this model, which we review here. Its conceptual basis is radically different from field theoretic inflation and it has no trans-Planckian problem, but its predictions for power spectra will be shown to fit extant data equally well, and the tensor-to-scalar ratio agrees with experimental observations.

We investigate whether a violation of the distance duality relation (DDR) $D_L(z)=(1+z{)}^2{D}_A(z)$ connecting the angular diameter and luminosity distances can explain the Hubble tension and alter the evidence for dynamical dark energy in recent cosmological observations. We constrain five phenomenological parametrizations of DDR violation using baryon acoustic oscillation measurements from the DESI survey calibrated with the sound horizon derived from Planck cosmic microwave background data and the $\mathrm{Pantheon}+\text{Type}$ Ia supernova (SNIa) catalog calibrated with the supernova absolute magnitude from the Supernovae $H_0$ for the equation of state program. We find that two toy models can resolve the tension: a constant offset in the DDR (equivalent to a shift in the calibration of the SNIa data) $D_L(z)/D_A(z)\simeq 0.925(1+z{)}^2$, which leaves the hint for evolving dark energy unaffected, or a change in the power-law redshift dependence of the DDR restricted to $z\lesssim 1$, $D_L(z)/D_A(z)\simeq (1+z{)}^{1.866}$, together with a constant phantom dark energy equation of state $w\sim -1.155$. The Bayesian evidence slightly favors the latter model. Our phenomenological approach motivates the investigation of physical models of DDR violation as a novel way to explain the Hubble tension.

Line-of-sight distortions of the cosmic microwave background (CMB), including gravitational lensing, cosmic birefringence, and patchy screening, encode crucial cosmological information. While quadratic estimators (QE) have been excellent tools for extracting these signals, they become suboptimal for current- and next-generation CMB surveys, failing to maximize signal-to-noise and suffering from bias contamination that standard bias-hardening techniques cannot mitigate. We present a joint maximum a posteriori framework that simultaneously reconstructs multiple distortion fields while explicitly accounting for their mutual contamination. For cosmic birefringence searches, our method achieves up to 2.5 times improvement in reconstruction noise compared to the QE, while significantly reducing CMB lensing-induced biases up to a factor of 5. These gains in lensing biases manifest not only in deep polarization surveys like CMB-S4 and SPT-3G, but also in higher-noise experiments like Simons Observatory, where our method reduces lensing-induced biases by a factor of two thanks to the power of delensing. Our code provides a first step to robust analyses of CMB secondary anisotropies, their cross-correlations with large-scale structure, and ultimately enabling more sensitive searches for primordial $B$-modes.

Assuming that (1) the Universe underwent a postinflationary accelerated expansion phase driven by a fluid with equation of state $P=w\rho$ and $-1<w<-1/3$, that (2) the cosmic horizon in an accelerating, quasi–de Sitter Universe has a temperature inversely proportional to the proper size of the horizon, and that (3) we are static observers, we calculate the frozen-in density of a stable particle of mass $m$ produced by the cosmic horizon that does not undergo any number-changing processes in the late Universe. We find that, as a function of the equation of state and the temperature when radiation domination starts and the quasi–de Sitter phase ends, the mass of the dark matter producing the observed cosmological abundance via this mechanism ranges from 10 keV up to close to the Planck scale.

In this paper, we investigate the impact of the lensing anomaly in Planck cosmic microwave background (CMB) data on the nature of dark energy (DE). We constrain the state equation ($w_0,w_a$) of DE with the lensing scaling parameter $A_L=1$ and varying $A_L$, using the Planck PR3 and two updated Planck PR4 likelihoods, camspec and hillipop, respectively, combined with DESI baryon acoustic oscillation (BAO) and $\mathrm{Pantheon}+\text{supernova}$ data. As expected, when $A_L$ is allowed to vary, the evolving DE is not preferred due to the degeneracy between $w_0,w_a$ and $A_L$. In particular, we also consider replacing DESI BAO data with pre-DESI BAO in our analysis, and observe that DESI BAO appears to exacerbate the lensing anomaly, which is caused by the smaller matter density ${\mathrm{\Omega }}_m$ it prefers, however, this effect can be offset by the shifts in $w_0$ and $w_a$ preferring the evolving DE. Our work indicates that the lensing anomaly in Planck data is worth carefully reconsidering when new cosmological survey data is combined with CMB.

Strong gravitational lenses enable direct inference of halo abundance and internal structure, which in turn enable constraints on the nature of dark matter and the primordial matter power spectrum. However, the density profiles of dark subhalos around the main deflector of a strong lens system also depend on tidal evolution inside the host, complicating the interpretation of strong-lensing inferences. We present a model for subhalo tidal evolution that accurately predicts the bound mass function and the density profiles of tidally stripped subhalos that appear near the Einstein radius of a typical deflector for a variety of dark matter models. This model matches predictions from the semianalytic model (SAM) galacticus, but enables the simulation of subhalo populations in seconds, rather than hours. We use this model to examine the expected number of subhalos near the Einstein radius of a typical lens, and examine their lensing signals. We show that in cold dark matter the amplitude of the bound mass function is suppressed by a factor of 20 relative to the infall mass function, and 87% of subhalos appearing in projection near the Einstein radius of a typical strong lensing deflector have lost more than 80% of their mass since infall. Tidal stripping becomes increasingly severe in dark matter models with suppressed small-scale power, such as warm dark matter. This model will be used to forward model subhalo populations in forthcoming analyses of strong lens systems.

In the past few years, NICER data has enabled mass and radius inferences for various pulsars, and thus shed light on the equation of state for dense nuclear matter. This is achieved through a technique called pulse profile modeling. The importance of the results necessitates careful validation and testing of the robustness of the inference procedure. In this paper, we investigate the effect of sampler choice for x-psi (x-ray pulse simulation and inference), an open-source package for pulse profile modeling and Bayesian statistical inference that has been used extensively for analysis of NICER data. We focus on the specific case of the high-mass pulsar PSR $\mathrm{J}0740+6620$. Using synthetic data that mimics the most recently analyzed NICER and XMM-Newton datasets of PSR $\mathrm{J}0740+6620$, we evaluate the parameter recovery performance, convergence, and computational cost for multinest’s multimodal nested sampling algorithm and ultranest’s slice nested sampling algorithm. We find that both samplers perform reliably, producing accurate and unbiased parameter estimation results when analyzing simulated data. We also investigate the consequences for inference using the real data for PSR $\mathrm{J}0740+6620$, finding that both samplers produce consistent credible intervals.

Rotation plays an important role in the evolution of most types of stars; in particular, it can have a strong influence on the evolution of a newly born protoneutron star. In this study, we investigate the effects of rotation on four snapshots of the evolution of protoneutron stars with hyperons and $\mathrm{\Delta }$ resonances in their cores, from birth as neutrino-rich objects to maturity as cold, catalyzed neutron stars. We focus on the effects of uniform rotation on the macroscopic structure of the star at three rotational frequencies—346.53 Hz, 716 Hz, and the Kepler frequency. Our investigation indicates that the impact of rotation at frequencies of 346.53 and 716 Hz causes minor changes in the maximum gravitational mass but leads to significant changes in the stellar radius, particularly for stars with masses smaller than $2M_{\odot }$. However, we observe drastic changes in the star’s mass and radius when considering the Kepler frequency. In addition, we investigate other relevant characteristics of the rotating protoneutron stars as they evolve such as the moment of inertia, compactness, central temperature, and Kerr parameter. Our results suggest that the inclusion of new degrees of freedom in the stellar core lead the star to be more sensitive to rotational dynamics, owing to an increase in compactness, a decrease in the central temperature, and a decrease in the moment of inertia.

octopus is a simulation software specifically developed to calculate the response of a given mechanical system. The initial purpose of its development was to support the design and the commissioning of the superattenuator (SA), i.e., the vibration isolator designed to inhibit the transmission of the seismic noise at the level of the test mass of the Virgo gravitational waves detector. octopus analytically computes the transfer functions of a complex mechanical system using the impedance matrix formalism in the frequency domain and provides an advanced and versatile mechanical simulation tool. This methodology allows to analyze a large set of user-defined mechanical layouts. Within the context of advanced seismic isolation system design, the present software allows to accurately estimate the behavior of specific mechanical components in terms of performance and general requirements achievement, both in open loop and also when feedback control loops are implemented. In the present work, several topics will be addressed. First, the mathematical principles behind the impedance formalism will be introduced, focusing on the modeling of basic elements, which constitute the principal blocks used to develop and build complex mechanical models. Then, as case studies, two examples of mechanical systems models will be presented: the computation of the thermal noise of a body suspended by an elastic beam and the complete model of a superattenuator. To validate the accuracy of the simulation tool, comparisons with experimental measurements will be given in both cases.

Studying exotic hadrons is a challenge against the conventional quark model, providing us with a good platform to deepen our understanding of the strong interaction. An inclusive study of the exotic hadrons in vacuum and at finite temperature is an intriguing approach to shed light on their nature. As a first step, we study the $Z_c(3900)$ in both the $D{\overline{D}}^{*}$ hadronic molecular and the triangle singularity pictures, and discuss the behaviors of $Z_c(3900)$ at finite temperature in these two different pictures. As a result, we show the properties that its mass becomes smaller and its width becomes larger when the temperature increases, which are seen commonly in the hadronic molecular picture and in the triangle singularity picture. The enhanced widths in hot medium indicate that the $Z_c(3900)$ will be dissociated at a sufficiently high temperature. This feature is also reflected by a decrease of the effective couplings in the hadronic molecular picture. It is concluded that, not only in vacuum but also in hot medium, the behaviors of $Z_c(3900)$ are similar in the two different interpretations of $Z_c(3900)$.

At leading power accuracy, the QCD light-cone distribution amplitudes (LCDAs) for a heavy meson can be matched onto the LCDAs in the framework of heavy-quark effective theory (HQET) through a factorization formula. We examine the power corrections to this factorization in the renormalon model, which can associate the power corrections originating from high-twist contributions to the divergent series in a matching kernel. Our analysis indicates that the dominant power corrections originate from the virtual part of the vertex bubble chain diagrams, which generate poles at $w=n+\frac{1}{2},\forall n\in \mathbb{N}$ and $w=1$ in the Borel plane. Employing phenomenological models for both HQET and QCD LCDA, we present a numerical estimate. The results indicate that the power corrections in the peak region are approximately 22% for the D meson and 7% for the $\overline{\mathrm{B}}$ meson. These findings showcase the magnitude and potential importance of power corrections in achieving high-precision phenomenological predictions for heavy mesons.

The exact solution of the Dirac equation for fermions coupled to an external periodic chiral condensate (chiral spiral) is used to obtain the exact formula for the Wigner function (up to the quantum loop corrections). We find that the resulting expressions for various coefficients of the Wigner function exhibit properties that cannot be reproduced within the standard semiclassical expansion. The formula for the axial vector component of the Wigner function can be conveniently used to study spin polarization effects and illustrate connections between the spin density matrix and axial current. In particular, we find that during an adiabatic change of the periodic potential into a uniform one, the polarization vector is twisted from its original direction.

In this work, the perturbative and nonperturbative contributions to the heavy quark (HQ) momentum ($\kappa$) as well as spatial ($D_s$) diffusion coefficients are computed in a weak background magnetic field. The formalism adopted here involves calculation of the in-medium potential of the HQ in a weak magnetic field, which then serves as a proxy for the resummed gluon propagator in the calculation of HQ self-energy ($\mathrm{\Sigma }$). The self-energy determines the scattering rate of HQs with light thermal partons, which is subsequently used to evaluate $\kappa$ and $D_s$. It is observed that nonperturbative effects play a dominant role at low temperature. The spatial diffusion coefficient, $2\pi T{D}_s$, exhibits good agreement with recent lattice QCD results. These findings can be applied to calculate the heavy quark directed flow at RHIC and LHC energies. An extension of this formalism to the case of finite HQ momentum has also been attempted.

We assess the effect of the cosmic neutrino background ($\mathrm{C}\nu \mathrm{B}$) on superradiant instabilities caused by an ultralight scalar field around spinning black holes (BHs). When the scalar couples to neutrinos via a Yukawa interaction, thermal corrections from the $\mathrm{C}\nu \mathrm{B}$ induce a quartic self-interaction and an effective mass term for the scalar. We show that, for Yukawa couplings as small as $y_{\varphi \nu }\sim {10}^{-16}$ (for astrophysical BHs) or ${10}^{-20}$ (for supermassive BHs), the quartic term can quench the instability and set observable bounds, even if the scalar does not constitute dark matter. We assess the robustness of these constraints against several sources of uncertainty, including gravitational focusing of relic neutrinos, galactic clustering, and nonlinear backreaction. An enhanced local neutrino density weakens the bounds by up to an order of magnitude compared to a uniform background, yet the induced self-interaction remains strong enough to significantly affect the superradiant dynamics. Our results open a new observational window on neutrino-coupled scalars via BH superradiance.

Protoneutron stars, highly compact objects formed in the core of exploding supernovae (SNe), are powerful sources of axionlike particles (ALPs). In the SN core, ALPs are dominantly produced via nucleon-nucleon bremsstrahlung and pion conversion, resulting in an energetic ALP spectrum peaked at energies $\mathcal{O}(100)\mathrm{MeV}$. In this work, we revisit the diffuse ALP background, produced from all past core-collapse supernovae, and update the constraints derived from Fermi-LAT observations. Assuming the maximum ALP-nucleon coupling allowed by the SN 1987A cooling, we set the upper limit $g_{a\gamma \gamma }\lesssim 2\times {10}^{-13}{\mathrm{GeV}}^{-1}$ for ALP mass $m_a\lesssim {10}^{-10}\mathrm{eV}$, which is approximately a factor of two improvement with respect to the existing bounds. On the other hand, for $m_a\gtrsim {10}^{-10}\mathrm{eV}$, we find that including pion conversion strengthens the bound on $g_{a\gamma \gamma }$, approximately by a factor of two compared to the constraint obtained from bremsstrahlung alone. Additionally, we present a sensitivity study for future experiments such as AMEGO-X, e-ASTROGAM, GRAMS-balloon, GRAMS-satellite, and MAST. We find that the expected constraint from MAST would be comparable to Fermi-LAT bound. However, SN 1987A constraint remains one order of magnitude stronger as compared to the bound derived from the current and future gamma-ray telescopes.

The FASER experiment was designed to study long-lived dark sector particles and neutrinos traveling in the forward direction at the LHC. Neutrinos are predominantly produced from meson decays, which also result in an intense energetic flux of muons in the forward direction regularly observed by FASER. So far, these muons are treated only as backgrounds to neutrino and new physics studies, and extensive effort is required to suppress them. In this study, we consider the opposite scenario and use muons produced in the forward direction to produce new muonphilic scalars, which can then be searched for at the FASER detector. To minimize the backgrounds for this search, we make use of an upgraded preshower component, which is expected to be installed at FASER before the end of Run 3, and is capable of spatially resolving two energetic photons. We find that FASER, and its upgrade, FASER2, can probe currently unconstrained regions of parameter space, including regions that can potentially explain the $(g-2{)}_{\mu }$ anomaly. This highlights the physics opportunities that the intense TeV muon beam at the LHC can bring.

Searches for axionlike particles (ALPs) with masses in the GeV range are a central objective of present and future intensity-frontier experiments. Interpreting these searches demands a reliable description of ALP production and decay. The prescription currently adopted by the community depends on unphysical chiral-rotation parameters, wrongly describes the mass scaling of the ALP flux, and ignores mixing with heavy pseudoscalar resonances. We introduce the framework that treats GeV-scale ALP interactions self-consistently, includes their mixing with heavier excitations $\pi (1300)$, $\eta (1295)$, and $\eta (1440)$, and properly describes production channels. When applying our description to proton beam experiments, we find that existing bounds and projected sensitivities shift by up to an order of magnitude relative to earlier estimates. We further delineate the dominant theoretical uncertainties, which originate from the still-incomplete experimental knowledge of the light-meson spectrum.

Lattice studies of the doubly charm tetraquark $T_{cc}=cc\overline{u}\overline{d}$ require the determination of the $D{D}^{*}$ scattering amplitude, which most often incorporate only meson-meson interpolators. We additionally incorporate diquark-antidiquark operators and find that these have some impact on certain eigenenergies. This study presents the first extraction of the $D{D}^{*}$ scattering amplitude based on the meson-meson as well as diquark antidiquark interpolators. The effect of the additional operators renders slightly smaller values of $p$ $\cot {\delta }_0$ and a $T_{cc}$ pole slightly closer to the threshold. The scattering amplitude is extracted from eigenenergies by adopting plane-wave and effective-field-theoretic methods, which also incorporate the left-hand cut and address the partial wave mixing. The $T_{cc}$ is found to be a subthreshold resonance with a pole at $m_{T_{cc}}-m_D-m_{D^{*}}=-{5.2}_{-0.8}^{+0.7}-i·{6.3}_{-4.8}^{+2.4}\mathrm{MeV}$, employing coordinated lattice simulations (CLS) ensembles with $m_{\pi }\simeq 280\mathrm{MeV}$ and the distillation method. A more significant effect of diquark-antidiquark operators on eigen-energies is found for larger heavy quark masses relevant for $T_{bb}$. We find that deeply bound $T_{bb}$ does not emerge when employing only meson-meson operators, where each meson is separately momentum projected, while the deeply bound state emerges after adding local diquark antidiquark operators.

We evaluate the phase-space integrals that arise in double real emission diagrams for semi-inclusive deep-inelastic scattering at next-to-next-to-leading order in QCD. Utilizing the reverse unitarity technique, we convert these integrals into loop integrals, allowing us to employ integration-by-parts identities and reduce them to a set of master integrals. The master integrals are then solved using the method of differential equations and expressed in terms of Goncharov polylogarithms. By examining the series expansion in the dimensional regulator, we discover additional relations among some of the master integrals. As an alternative approach, we solve the master integrals by decomposing them into angular and radial components. The angular parts are evaluated using Mellin-Barnes representation, while special attention is given to the singular structures of the radial integrals to handle them accurately. Here the results are provided in terms of one-fold integrals over classical polylogarithms. This approach provides a clearer understanding of the origin of soft and collinear singularities.