Massive particles produced during inflation impact soft limits of primordial correlators. Searching for these signatures presents an exciting opportunity to uncover the particle spectrum in the inflationary epoch. We present nonperturbative methods to constrain intermediate-mass scalars ($0\le m/H<3/2$, where $H$ is the inflationary Hubble scale) produced during inflation, which give rise to a power-law scaling in the squeezed primordial bispectrum. Exploiting the large-scale structure consistency relations and the separate universe approach, we derive models for the late-time squeezed matter bispectrum and collapsed matter trispectrum sourced by these fields. To validate our models, we run $N$-body simulations with the “cosmological collider” squeezed bispectrum for two different particleī masses. Our models yield unbiased constraints on the amplitude of non-Gaussianity, $f_{\mathrm{NL}}^{\mathrm{\Delta }}$, from the squeezed bispectrum and collapsed trispectrum deep into the nonlinear regime ($k_{\max }\approx 2h/\mathrm{Mpc}$ at $z=0$). We assess the information content of these summary statistics, emphasizing the importance of sample variance cancellation in the matter sector. We also study the scale-dependent halo bias in our simulations. For mass-selected halos, the non-Gaussian bias estimated from our simulations agrees with predictions based on (i) separate universe simulations and (ii) universal mass functions. With further work, these results can be used to search for inflationary massive particle production with upcoming galaxy surveys.

Causal parametric representations of neutron-star equations of state are constructed here using Chebyshev polynomial based spectral expansions. The accuracies of these representations are evaluated for a collection of model equations of state from a variety of nuclear-theory models and also a collection of equations of state with first- or second-order phase transitions of various sizes. These tests show that the Chebyshev based representations are convergent (even for equations of state with phase transitions) as the number of spectral basis functions is increased. This study finds that the Chebyshev based representations are generally more accurate than a previously studied power-law based spectral representation, and that pressure-based representations are generally more accurate than those based on enthalpy.

Ultralight vectors can extract energy and angular momentum from a Kerr black hole (BH) due to superradiant instability, resulting in the formation of a BH-condensate system. In this work, we carefully investigate the evolution of this system numerically with multiple superradiant modes. Simple formulas are obtained to estimate important timescales, maximum masses of different modes, as well as the BH mass and spin at various times. Due to the coexistence of modes with small frequency differences, the BH-condensate system emits gravitational waves with a unique beat signature, which could be directly observed by current and projected interferometers. Besides, the current BH spin-mass data from the binary BH merger events already exclude the vector mass in the range $5\times {10}^{-15}\mathrm{eV}<\mu <9\times {10}^{-12}\mathrm{eV}$.

Binary neutron star mergers play an important role in nuclear astrophysics: Their gravitational wave and electromagnetic signals carry information about the equation of state of cold matter above nuclear saturation density, and they may be one of the main sources of r-process elements in the Universe. Neutrino-matter interactions during and after merger impact the properties of these electromagnetic signals and the relative abundances of the produced r-process elements. Existing merger simulations are, however, limited in their ability to realistically model neutrino transport and neutrino-matter interactions. Here, we perform a comparison of the impact of the use of state-of-the art two-moment or Monte Carlo transport schemes on the outcome of merger simulations, for a single binary neutron star system with a short-lived neutron star remnant [(5–10) ms]. We also investigate the use of different reaction rates in the simulations. While the best transport schemes generally agree well on the qualitative impact of neutrinos on the system, differences in the behavior of the high-density regions can significantly impact the collapse time and the properties of the hot tidal arms in this metastable merger remnant. The chosen interaction rates and transport algorithm as well as recent improvements by Radice et al. to the two-moment algorithms can all contribute to changes at the (10–30)% level in the global properties of the merger remnant and outflows. The limitations of previous moment schemes fixed by Radice et al. also appear sufficient to explain the large difference that we observed in the production of heavy-lepton neutrinos in a previous comparison of Monte Carlo and moment schemes in the context of a low-mass binary neutron star system.

We consider the intermediate mass-ratio inspiral of a stellar-mass compact object with an intermediate-mass black hole that is surrounded by a dark matter density spike. The interaction of the inspiraling black hole with the dark matter particles in the spike leads to dynamical friction. This can alter the dynamics of the black hole binary, leaving an imprint on the gravitational wave signal. Previous calculations did not include in the evaluation of the dynamical friction coefficient the contribution from particles that move faster than the inspiraling black hole. This term is neglected in the standard Chandrasekhar treatment where only slower moving particles contribute to the decelerating drag. Here, we demonstrate that dynamical friction produced by the fast moving particles can have a significant effect on the evolution of a massive binary within a dark matter spike. For a density profile $\rho \propto r^{-\gamma }$ with $\gamma \lesssim 1$, the dephasing of the gravitational waveform can be several orders of magnitude larger than estimated using the standard treatment. As $\gamma$ approaches 0.5 the error becomes arbitrarily large. Finally, we show that dynamical friction tends to make the orbit more eccentric for any $\gamma <1.8$. However, energy loss by gravitational wave radiation is expected to dominate the inspiral, leading to orbital circularization in most cases.

The quantum noise in gravitational-wave detectors can be suppressed in a broadband by frequency-dependent squeezing. It usually requires one large scale filter cavity and even two, for example in the low frequency detector of Einstein Telescope, which is a detuned dual recycling Fabry-Perot Michelson interferometer. In this paper, we study the feasibility of replacing two filter cavities with a coupled-cavity, aiming to reduce the optical losses with less number of optics. It turns out this approach is only theoretically valid, however, the required parameters of the optics do not support practical implementation, which is consistent with the results in Jones et al. [Implications of the quantum noise target for the Einstein Telescope infrastructure design, Phys. Rev. D 101, 082002 (2020)]. Furthermore, we investigate the viability of utilizing Einstein-Podolsky-Rosen (EPR) squeezing to eliminate either one or two filter cavities in the Einstein Telescope. It turns out EPR squeezing would allow us to eliminate one filter cavity, and can potentially improve the detector sensitivity with the allowance of higher input squeezing level, benefiting from the longer length of the arm cavity which serves as one of the filter cavities for frequency-dependent squeezing.

We show how to use a worldline-instanton formalism to calculate, to leading order in the weak-field expansion, the momentum spectrum of nonlinear Breit-Wheeler pair production in fields that depend on time and one spatial coordinate. We find a nontrivial dependence on the width, $\lambda$, of the photon wave packet, and the existence of a critical point ${\lambda }_c$. For $\lambda <{\lambda }_c$ and a field with one peak, the spectrum has one peak where the electron and positron have the same energy. For $\lambda >{\lambda }_c$ this splits into two peaks. We calculate a high-energy ($\mathrm{\Omega }\gg 1$) expansion, which to leading order agrees with the results obtained by replacing the spacetime field with a plane wave and using the well-known Volkov solutions. We also calculate an expansion for $\mathrm{\Omega }\sim a_0\gg 1$, where the field is strong enough to significantly bend the trajectories of the fermions despite $\mathrm{\Omega }\gg 1$.

In this paper, we propose two sets of different $CP$-sensitive observables inspired by the Higgs production in association with the top quark. We employ a dark matter simplified model that couples a scalar mediator with top quarks. The reconstruction of the kinematic variables is presented at next to leading order (NLO) accuracy for events associated with this massive scalar particle, which is assumed to be vanishing to invisible decays in a detector such as ATLAS. We build these observables by taking advantage of the similarity between the scalar coupling with the top quark and the factorization theorem in the total scattering amplitude, in order to represent the basis in which the phase space is parametrized. A twofold approach employs the direct implementation of the four-momentum phase space measure in building $CP$ sensitive observables such as $b_2$ for the Higgs, and the spin polarization of the top-quark decays in the narrow width approximation for the employed model. We studied the asymmetries of these distributions to test for any improvement in increasing the exclusion region for the $g_{u_{33}}^S-g_{u_{33}}^P$ parameters associated with this vanishing scalar particle. We have found no significant effect in the exclusion limits by using the forward-backward asymmetry distributions and the full-shaped ones. Considering the case of an invisible mediator with mass of ${10}^{-2}\mathrm{GeV}$ for a luminosity of $300{\mathrm{fb}}^{-1}$ expected at the end of Run 3, the best limits for $g_{u_{33}}^S$ and $g_{u_{33}}^P$ at NLO accuracy were obtained using the variables ${\tilde{b}}_2^{\widehat{y}}$ and $b_2$ respectively, with corresponding limits set to $[-0.0425,0.0425]$ and $[-0.83,0.83]$ at 68% CL.

Jet-energy calibration is an important aspect of many measurements and searches at the LHC. Currently, these calibrations are performed on a per-jet basis, i.e., agnostic to the properties of other jets in the same event. In this work, we propose taking advantage of the correlations induced by momentum conservation between jets in order to improve their jet-energy calibration. By fitting the $p_T$ asymmetry of dijet events in simulation, while remaining agnostic to the $p_T$ spectra themselves, we are able to obtain correlation-improved maximum likelihood estimates. This approach is demonstrated with simulated jets from the CMS detector, yielding a 3%–5% relative improvement in the jet-energy resolution, corresponding to a quadrature improvement of approximately 35%.

In this study, we explore the interactions between mesons and baryons in the open heavy sectors to identify potential triple-heavy molecular pentaquarks. We derive the meson-baryon interaction potentials using the vector meson exchange mechanism within the extended local hidden gauge formalism. The scattering amplitudes are computed by solving the coupled-channel Bethe-Salpeter equation, revealing several bound systems. By analyzing the poles of these amplitudes in the complex plane, we determine the masses and widths of these bound states. Additionally, we evaluate the couplings and compositeness of different channels within each bound system to assess their molecular characteristics. Our predictions include 4 ${\mathrm{\Omega }}_{ccc}$-like states, 4 ${\mathrm{\Omega }}_{bbb}$-like states, 14 ${\mathrm{\Omega }}_{bcc}$-like states, and 10 ${\mathrm{\Omega }}_{bbc}$-like states, which could be targets for future experimental investigations.

We consider the Dirac field uniformly rotating with angular velocity $\mathrm{\Omega }$ and also subject to the constant magnetic field $\mathit{B}$ directed along the rotation axis. The causal states are constrained to the interior of the light cylinder of radius $c/\mathrm{\Omega }$. When this radius is smaller than the system size, as in the quark-gluon plasma, the effect of the boundary on the fermion spectrum is critical. We derive the fermion spectrum and study its properties. We compute the intensity of the electromagnetic radiation emitted due to transitions between the fermion states. We study its dependence on energy and angular momentum for different values of the angular velocity and the magnetic field. Rotation has enormous impact on the electromagnetic radiation by the quark-gluon plasma with or without the magnetic field.

The minimum seesaw model with two right-handed neutrinos is considered, where the lightest neutrino is naturally massless. Instead of adopting texture zeros in the lepton Yukawa matrices, which cause both theoretical and experimental troubles, here we propose two-$\mathit{\epsilon }$ textures, where $\mathit{\epsilon }$ is a small number. Combined with neutrino oscillation experimental data, we find that a large $CP$ angle is preferred for the normal neutrino mass order. In contrast, the $CP$ angle almost vanishes for the inverted order. This can be well tested in near-future experiments, such as Hyper-Kamiokande. Besides, the predicted effective Majorana neutrino mass $m_{ee}$ and the total neutrino mass $\sum m_i^{\nu }$ are also within reach of ongoing or future experiments.

There is a large and growing interest in observations of small-scale structure in dark matter. We propose a new way to probe dark matter structures in the $\sim 10–{10}^8{M}_{\odot }$ range. This allows us to constrain the primordial power spectrum over shorter distances scales than possible with direct observations from the CMB. For $k$ in the range $\sim 10–1000{\mathrm{Mpc}}^{-1}$ our constraints on the power spectrum are orders of magnitude stronger than previous bounds. We also set some of the strongest constraints on dark matter isocurvature perturbations. Our method relies on the heating effect such dark matter substructures would have on the distribution of stars in an ultrafaint dwarf galaxy. Many models of inflation produce enhanced power at these short distance scales and can thus be constrained by our observation. Further, many dark matter models such as axion dark matter, self-interacting dark matter and dissipative dark matter, produce dense structures which could be constrained this way.

We place limits on dark matter made up of compact objects significantly heavier than a solar mass, such as MACHOs or primordial black holes (PBHs). In galaxies, the gas of such objects is generally hotter than the gas of stars and will thus heat the gas of stars even through purely gravitational interactions. Ultrafaint dwarf galaxies (UFDs) maximize this effect. Observations of the half-light radius in UFDs thus place limits on MACHO dark matter. We build upon previous constraints with an improved heating rate calculation including both direct and tidal heating, and consideration of the heavier mass range above ${10}^4{M}_{\odot }$. Additionally we find that MACHOs may lose energy and migrate in to the center of the UFD, increasing the heat transfer to the stars. UFDs can constrain MACHO dark matter with masses between about $10M_{\odot }$ and ${10}^8{M}_{\odot }$ and these are the strongest constraints over most of this range.

The lepton flavor violating (LFV) decays $h,Z\to e_b{e}_a$, and $e_b\to e_a\gamma$ are discussed in a class of general 3-3-1 models adding heavy neutral leptons and singly charged Higgs bosons to accommodate experimental data of neutrino oscillation and $(g-2{)}_{e_a}$ anomalies of charged leptons through the inverse seesaw mechanism. We show that the models with the minimal number of inverse seesaw neutrinos cannot reach the $1\sigma$ range of $(g-2{)}_{\mu }$ data due to the experimental upper bounds on decay rates of $(\tau \to \mu \gamma )$ and $(\mu \to e\gamma )$. Features of LFV decays are presented in detail, focusing on the regions of parameter space satisfying the $1\sigma$ ranges of $(g-2{)}_{e,\mu }$ data.

As the planning stages for a high energy muon collider enter a more concrete era, an important question arises as to what new physics could be uncovered. A TeV-scale muon collider is also a vector boson fusion (VBF) factory with a very clean background, and as such it is a promising environment to look for new physics that couples to the electroweak (EW) sector. In this paper, we explore the ability of a future TeV-scale muon collider to search for Majorana and Dirac heavy neutral leptons (HNLs) produced via EW bosons. Employing a model-independent, conservative approach, we present an estimation of the production and decay rate of HNLs over a mass range between 200 GeV and 9.5 TeV in two benchmark collider proposals with $\sqrt{s}=3$, 10 TeV, as well as an estimation of the dominant Standard Model (SM) background. We find that exclusion limits for the mixing between the HNLs and SM neutrinos can be as low as $\mathcal{O}({10}^{-6})$. Additionally, we demonstrate that a TeV-scale muon collider allows for the ability to discriminate between Majorana and Dirac type HNLs for a large range of mixing values.

The simulation of lattice gauge theories on quantum computers necessitates digitizing gauge fields. One approach involves substituting the continuous gauge group with a discrete subgroup, but the implications of this approximation still need to be clarified. To gain insights, we investigate the subduction of $SU(2)$ and $SU(3)$ to discrete crystal-like subgroups. Using classical lattice calculations, we show that subduction offers valuable information based on subduced direct sums, helping us identify additional terms to incorporate into the lattice action that can mitigate the effects of digitization. Furthermore, we compute the static potentials of all irreducible representations of $\mathrm{\Sigma }(360\times 3)$ at a fixed lattice spacing. Our results reveal a percent-level agreement with the Casimir scaling of $SU(3)$ for irreducible representations that subduce to a single $\mathrm{\Sigma }(360\times 3)$ irreducible representation. This provides a diagnostic measure of approximation quality, as some irreducible representations closely match the expected results while others exhibit significant deviations.

We investigate the higher-twist generalized parton distributions (GPDs) of the pion and kaon at zero skewness by adopting the overlap representation within the light-cone formalism. Using the wave functions of pion and kaon deduced from a light-cone quark model (LCQM), we calculate the twist-3 and twist-4 GPDs $E_2(x,0,t)$, $G_2(x,0,t)$, $F_3(x,0,t)$, and $H_3(x,0,t)$ of valence quarks inside the pion and kaon mesons. Numerical results for these higher-twist GPDs of valence quark and antiquark are presented. By taking the forward limit, we also present the numerical results for the corresponding twist-3 and twist-4 parton distribution functions (PDFs) $e(x)$ and $f_3(x)$ of pion and kaon. We further study the relations between $e(x)$ or $f_3(x)$ and the twist-2 unpolarized PDF $f_1(x)$.

Inspired by the newly observed three scalar states $f_0(2020)$, $f_0(2330)$, and $f_0(2470)$ by the BESIII collaboration in $J/\psi \to \gamma {\eta }^{\prime }{\eta }^{\prime }$, we carried out the study of spectroscopic behavior of these high-lying unflavored scalar mesonic states. In this work, using the phenomenological description of radial $(n,M^2)$ trajectory and the quark pair creation model, we discussed the assignments of the $f_0(2020)$, $f_0(2330)$, and $f_0(2470)$ associated with the $f_0(2200)$ as the isoscalar high-lying scalar mesonic states and predicted the spectroscopic properties of their high-lying partners. The present study may provide valuable information for the construction of the scalar meson family.

Many machine learning applications involve learning a latent representation of data, which is often high-dimensional and difficult to directly interpret. In this work, we propose “moment pooling,” a natural extension of deep sets networks which drastically decreases the latent space dimensionality of these networks while maintaining or even improving performance. Moment pooling generalizes the summation in deep sets to arbitrary multivariate moments, which enables the model to achieve a much higher effective latent dimensionality for a fixed learned latent space dimension. We demonstrate moment pooling on the collider physics task of quark/gluon jet classification by extending energy flow networks (EFNs) to moment EFNs. We find that moment EFNs with latent dimensions as small as 1 perform similarly to ordinary EFNs with higher latent dimension. This small latent dimension allows for the internal representation to be directly visualized and interpreted, which in turn enables the learned internal jet representation to be extracted in closed form.