The dark photon not only provides a portal linking dark sector particles and ordinary matter but also is a well-motivated dark matter candidate. We propose to detect the dark photon dark matter through the inverse Compton-like scattering process $p+{\gamma }^{\prime }\to p+\gamma$. Thanks to the ultrahigh energy primary cosmic rays, we find that such a method is able to probe the dark photon mass from ${10}^{-2}\mathrm{eV}$ down to ${10}^{-19}\mathrm{eV}$ with the expected sensitivity of eROSITA $X$-ray telescope, which can extend the current lower limit of dark photon mass from Jupiter’s magnetic fields experiment by about three orders of magnitude.

We describe a proposed experimental search for exotic spin-dependent interactions using rotationally modulated source masses and an atomic magnetometer array. Rather than further improving the magnetometer sensitivity, noise reduction can be another way to reach higher measurement precision. In this work, we propose to use modulating techniques of the source masses to reduce the noise of the experiment. Better precision can be achieved if the fundamental frequency and harmonics of the rotating source masses are used to detect the new interactions. Furthermore, if an array of magnetometers are applied, the statistical precision can be improved, and some common-mode noises can be canceled. Our analysis and simulations indicate that the proposed experiment scheme can improve the detection precisions of three types of spin-dependent interactions by as much as $\sim 5$ orders of magnitude in the force range of $\sim \mathrm{cm}$ to $\sim 10\mathrm{m}$.

We investigate flavored gauge mediation models in which the Higgs and messenger doublets are embedded in multiplets of the discrete non-Abelian symmetry ${\mathcal{S}}_3$. In these theories, the ${\mathcal{S}}_3$ symmetry correlates the flavor structure of the quark and lepton Yukawa couplings with the structure of the messenger Yukawa couplings that contribute to the soft supersymmetry breaking mass parameters. We provide a systematic exploration of possible scenarios within this framework that can accommodate hierarchical quark and charged lepton masses, and examine the resulting phenomenological implications in each case. We find a heavier spectrum for the superpartner masses compared to flavored gauge mediation models controlled by Abelian symmetries, which can be directly traced back to the need in our scenarios for two vectorlike pairs of messenger fields for viable electroweak symmetry breaking.

A top-down approach to the flavor puzzle leads to eclectic flavor groups which include modular and traditional flavor symmetries. Based on examples of semirealistic ${\mathbb{T}}^2/{\mathbb{Z}}_3$ orbifold compactifications of heterotic string theory, we discuss the breakdown patterns of the eclectic flavor group via the interplay of vacuum expectation values (vevs) of moduli and flavon fields. This leads to an attractive flavor scheme with various possibilities to obtain “flavor hierarchies” through the alignment of these vevs. Despite the fact that the top-down approach gives strong restrictions for bottom-up flavor model building, it seems to be well suited to provide a realistic flavor pattern for quarks and leptons.

We develop a methodology for the computation of the $K\to \ell {\nu }_{\ell }{{\ell }^{\prime }}^{+}{{\ell }^{\prime }}^{-}$ decay width using lattice QCD and present an exploratory study here. We use a scalar function method to account for the momentum dependence of the decay amplitude and adopt the infinite-volume reconstruction method to reduce the systematic errors such as the temporal truncation effects and the finite-volume effects. We then perform a four-body phase-space integral to obtain the decay width. The only remaining technical problem is the possible power-law finite-volume effects associated with the process of $K\to \pi \pi \ell {\nu }_{\ell }\to \ell {\nu }_{\ell }{{\ell }^{\prime }}^{+}{{\ell }^{\prime }}^{-}$, where the intermediate state involves multiple hadrons. In this work, we use a gauge ensemble of a twisted-mass fermion with a pion mass $m_{\pi }=352\mathrm{MeV}$ and a nearly physical kaon mass. At this kinematics, the $\pi \pi$ in the intermediate state cannot be on shell simultaneously, as $2m_{\pi }>m_K$, and the finite-volume effects associated with the $\pi \pi$ state are exponentially suppressed. Using the developed methods mentioned above, we calculate the branching ratios for four channels of $K\to \ell {\nu }_{\ell }{{\ell }^{\prime }}^{+}{{\ell }^{\prime }}^{-}$, and obtain the results comparable to the experimental measurements and ChPT predictions. Our work demonstrates the capability of lattice QCD to improve the Standard Model prediction in the $K\to \ell {\nu }_{\ell }{{\ell }^{\prime }}^{+}{{\ell }^{\prime }}^{-}$ decay width.

The process of pion axioproduction, $aN\to \pi N$, with an intermediate $\mathrm{\Delta }$ resonance is analyzed using baryon chiral parturbation theory. The $\mathrm{\Delta }$ resonance is included in two ways: First, deriving the $a\mathrm{\Delta }N$-vertices, the axion is brought into contact with the resonance, and, second, taking the results of $\pi N$ elastic scattering including the $\mathrm{\Delta }$, it is implicitly included in the form of a pion rescattering diagram. As a result, the partial wave cross section of axion-nucleon scattering shows an enhancement in the energy region around the $\mathrm{\Delta }$ resonance. Because of the isospin breaking, the enhancement is not as pronounced as previously anticipated. However, since the isospin breaking here is much milder than that for usual hadronic processes, novel axion-search experiments might still exploit this effect.

We show, from a diabatic analysis of lattice results for string breaking, that mixing of $Q\overline{Q}$ with open-flavor meson-meson configurations may be expressed through a mixing potential which is order $1/m_Q$. A relation between the minimum string breaking energy gap and the string tension comes out naturally. Using this relation, and matching the energy gap for $b\overline{b}$ with lattice QCD data, we study the mixing in the $c\overline{c}$ case without any additional parameter. A $1^{++}$ bound state very close below the $D^0{\overline{D}}^{*0}$ threshold, in perfect correspondence with ${\chi }_{c1}(3872)$, is predicted.

The $2\to 3$ scattering of longitudinal vector bosons (VBS) has been proven to be a complementary channel to measure the Higgs self-couplings in the Standard Model (SM) and the SM effective field theory (SMEFT) at colliders. We perform the first comprehensive study of all main $2\to 3$ VBS processes at high-energy muon colliders, especially including background analysis. The main contributing channels turn out to be the scattering of $W^{+}{W}^{-}\to W^{+}{W}^{-}h$, $ZZh$, and $hhh$. We obtain the constraints on $c_6$ and $c_{{\mathrm{\Phi }}_1}$ which are the Wilson coefficients of the dimension-6 operators relevant for Higgs self-couplings in the SMEFT. With the center-of-mass energies of 10 TeV and 30 TeV, we find the expected sensitivity to the coefficients $c_6/{\mathrm{\Lambda }}^2$ and $c_{{\mathrm{\Phi }}_1}/{\mathrm{\Lambda }}^2$ can reach the level of $0.01{\mathrm{TeV}}^{-2}$. The tightest constraints come from the $hhh$ channel, while the constraints from $WWh$ are also comparable. Our results crucially depend on selecting the longitudinal polarizations for the final $W$ and $Z$ bosons. We then study how the sensitivities change by varying the efficiency of tagging longitudinal polarizations, and find that the significance remains consistently high.

IsoDAR seeks to place a high-power-cyclotron and target combination, as an intense source of ${\overline{\nu }}_e$ at the level of $\sim {10}^{23}/\mathrm{year}$, close to a kiloton-scale neutrino detector in order to gain sensitivity to very short-baseline neutrino oscillations (${\overline{\nu }}_e\to {\overline{\nu }}_e$) and perform precision tests of the weak interaction, among other physics opportunities. Recently, IsoDAR has received preliminary approval to be paired with the 2.26 kton target volume liquid scintillator detector at the Yemi Underground Laboratory (Yemilab) in Korea, at a 17 m center-to-center baseline, and cavern excavation for IsoDAR is now complete. In this paper, we present the physics capabilities of IsoDAR@Yemilab in terms of sensitivity to oscillations (via inverse beta decay, IBD; ${\overline{\nu }}_e+p\to e^{+}+n$), including initial-state wave packet effects, and the weak mixing angle (via elastic scattering off atomic electrons, ${\overline{\nu }}_e+e^{-}\to {\overline{\nu }}_e+e^{-}$). We also introduce a study of IsoDAR sensitivity to new particles, such as a light $X$ boson, produced in the target that decays to ${\nu }_e{\overline{\nu }}_e$.

Understanding the properties of the strange ${\mathrm{\Lambda }}^{*}$ baryon resonances is a long-standing and fascinating problem. ${\mathrm{\Lambda }}_c$ charm-baryon semileptonic weak decays to these resonances are highly sensitive to their internal structure and can be used to test theoretical models. We have performed the first lattice-QCD computation of the form factors governing ${\mathrm{\Lambda }}_c$ semileptonic decays to a ${\mathrm{\Lambda }}^{*}$ resonance: the ${\mathrm{\Lambda }}^{*}(1520)$, which has negative parity and spin $3/2$. Here we present the resulting Standard Model predictions of the ${\mathrm{\Lambda }}_c\to {\mathrm{\Lambda }}^{*}(1520){\ell }^{+}{\nu }_{\ell }$ differential and integrated decay rates as well as angular observables. Furthermore, by combining the recent BESIII measurement of the ${\mathrm{\Lambda }}_c\to X{e}^{+}{\nu }_e$ inclusive semipositronic branching fraction [Phys. Rev. Lett. 121, 251801 (2018)] with lattice-QCD predictions of the ${\mathrm{\Lambda }}_c\to \mathrm{\Lambda }{e}^{+}{\nu }_e$, ${\mathrm{\Lambda }}_c\to n{e}^{+}{\nu }_e$, and ${\mathrm{\Lambda }}_c\to {\mathrm{\Lambda }}^{*}(1520)e^{+}{\nu }_e$ decay rates, we obtain an upper limit on the sum of the branching fractions to all other semipositronic final states. In particular, this upper limit constrains the ${\mathrm{\Lambda }}_c\to {\mathrm{\Lambda }}^{*}(1405)e^{+}{\nu }_e$ branching fraction to be very small, which may be another hint for a molecular structure of the ${\mathrm{\Lambda }}^{*}(1405)$.

The transport properties of dense QCD matter play a crucial role in the physics of neutron stars and their mergers but are notoriously difficult to study with traditional quantum field theory tools. Specializing to the case of unpaired quark matter in beta equilibrium, we approach the problem through the machinery of holography, in particular the V-QCD and D3-D7 models, and derive results for the electrical and thermal conductivities and the shear and bulk viscosities. In addition we compare the bulk to shear viscosity ratio to the speed of sound and find that it violates the so-called Buchel bound. Our results differ dramatically from earlier predictions of perturbative QCD, the root causes and implications of which we analyze in detail.

The moduli space approximation to kink dynamics permits a relativistic generalization if the Derrick scaling parameter is used as a collective coordinate. We develop a perturbative approach to the resulting relativistic moduli space by expanding the Derrick scaling parameter about unity and treating the higher-order Derrick modes as new degrees of freedom. This approach allows us to resolve (coordinate) singularities order by order and systematically incorporates relativistic corrections perturbatively in kink scattering. It gives an excellent description of kink-antikink collisions in ${\varphi }^4$ field theory already at first order and at higher order reproduces the fractal structure in the formation of the final state with an error of only 4%.

We present methods to rigorously extract parameter combinations that are constrained by data from posterior distributions. The standard approach uses linear methods that apply to Gaussian distributions. We show the limitations of the linear methods for current surveys and develop nonlinear methods that can be used with non-Gaussian distributions and are independent of the parameter basis. These are made possible by the use of machine-learning models, normalizing flows, to learn posterior distributions from their samples. These models allow us to obtain the local covariance of the posterior at all positions in parameter space and use its inverse, the Fisher matrix, as a local metric over parameter space. The posterior distribution can then be nonlinearly decomposed into the leading constrained parameter combinations via parallel transport in the metric space. We test our methods on two non-Gaussian, benchmark examples and then apply them to the parameter posteriors of the Dark Energy Survey and Planck CMB lensing. We illustrate how our method automatically learns the survey-specific, best constrained effective amplitude parameter $S_8$ for cosmic shear alone, cosmic shear and galaxy clustering, and CMB lensing. We also identify constrained parameter combinations in the full parameter space, and as an application we estimate the Hubble constant $H_0$ from large-structure data alone.

We use machine learning to distinguish between spherically-symmetric perturbations on a superhorizon scale which later collapse to primordial black holes (PBHs) and those which do not, focusing on the evolution of perturbations during radiation domination. We use a number of simulation results to train machine learning models, and test their accuracy using other simulation results which have not been used to train them. Different machine learning models and the parameters of each model lead to different accuracies, but we find that, overall, machine learning can predict PBH formation well. For instance, we show that the error rate can be of the order of ${10}^{-3}$. Hence, machine learning could be useful in estimating the abundance of PBHs accurately for each model of the early Universe which can predict PBH formation.

A measurement with high statistics of the differential energy spectrum of light elements in cosmic rays, in particular, of primary H plus He nuclei, is reported. The spectrum is presented in the energy range from 6 to 158 TeV per nucleus. Data was collected with the High Altitude Water Cherenkov (HAWC) Observatory between June 2015 and June 2019. The analysis was based on a Bayesian unfolding procedure, which was applied on a subsample of vertical HAWC data that was enriched to 82% of events induced by light nuclei. To achieve the mass separation, a cut on the lateral age of air shower data was set guided by predictions of CORSIKA/QGSJET-II-04 simulations. The measured spectrum is consistent with a broken power-law spectrum and shows a kneelike feature at around $E={24.0}_{-3.1}^{+3.6}\mathrm{TeV}$, with a spectral index $\gamma =-2.51\pm 0.02$ before the break and with $\gamma =-2.83\pm 0.02$ above it. The feature has a statistical significance of $4.1\sigma$. Within systematic uncertainties, the significance of the spectral break is $0.8\sigma$.

The direct detection of sub-GeV dark matter particles is hampered by their low energy deposits. If the maximum deposit allowed by kinematics falls below the energy threshold of a direct detection experiment, it is unable to detect these light particles. Mechanisms that boost particles from the Galactic halo can therefore extend the sensitivity of terrestrial direct dark matter searches to lower masses. Sub-GeV and sub-MeV dark matter particles can be efficiently accelerated by colliding with thermal nuclei and electrons of the solar plasma, respectively. This process is called “solar reflection.” In this paper, we present a comprehensive study of solar reflection via electron and/or nuclear scatterings using Monte Carlo simulations of dark matter trajectories through the Sun. We study the properties of the boosted dark matter particles, obtain exclusion limits based on various experiments probing both electron and nuclear recoils, and derive projections for future detectors. In addition, we find and quantify a novel, distinct annual modulation signature of a potential solar reflection signal which critically depends on the anisotropies of the boosted dark matter flux ejected from the Sun. Along with this paper, we also publish the corresponding research software.

The common phenomenon of lightning still harbors many secrets and only recently a new propagation mode was observed for negative leaders. While propagating in this “intensely radiating negative leader” (IRNL) mode a negative leader emits 100 times more very-high frequency (VHF) and broadband radiation than a more normal negative leader. We have reported that this mode occurs soon after initiation of all lightning flashes we have mapped as well as sometimes long thereafter. Because of the profuse emission of VHF the leader structure is very difficult to image. In this work we report on measurements made with the LOFAR radio telescope, an instrument primarily built for radio-astronomy observations. For this reason, as part of the present work, we have refined our time resolved interferometric 3-dimensional (TRI-D) imaging to take into account the antenna function. The images from the TRI-D imager show that during an IRNL there is an ionization front with a diameter in excess of 500 m where strong corona bursts occur. This is very different from what is seen for a normal negative leader where the corona bursts happen at the tip, an area of typically 10 m in diameter. The observed massive ionization wave supports the idea that this mode is indicative of a dense charge pocket.

Time delay interferometry (TDI) is a postprocessing technique used in the Laser Interferometer Space Antenna (LISA) to reduce laser frequency noise by building an equal-arm interferometer via combining time-shifted raw phase measurements. The set of so-called second generation TDI variables that sufficiently suppress laser frequency noise considering realistic LISA orbital dynamics has recently been expanded by a large number of additional solutions. In this paper, we characterize these new TDI channels by relating them to the well-known first generation variables $\alpha$, $\beta$, $\gamma$, and $\zeta$. We compute explicitly how each second generation variable can be approximated as a linear combination of these four first generation variables and show numerically that these approximations are accurate enough to model the noises not suppressed by TDI. We use these results to discuss how the newly found channels might be advantageous to use for the LISA data analysis. In addition, we demonstrate that newly found variants of the variable $\zeta$ significantly outperform the ones previously known from the literature.

We calculate the gravitational form factors (GFFs) and pressure, shear, and energy distributions for a quark state dressed with a gluon at one loop in QCD. We use the light-front Hamiltonian approach. In the light-front gauge, we use a two-component formalism to eliminate the constrained fields. The state may be thought of as a perturbative model for a relativistic spin-$1/2$ composite system having a gluonic degree of freedom. We compare the results with model calculations for a nucleon.

In this paper, we investigate the mutual impact between the dark matter (DM) requirements and the scalar sector in the scale invariant (SI) scotogenic model [A. Ahriche et al., J. High Energy Phys. 06 (2016) 182], that is motivated by the neutrino mass and DM within a classically SI framework. We show that the existence of annihilation channels that are mediated by the Higgs/dilaton may relax the DM relic density constraints on the contributions of $N_1{N}_1\to {\ell }_{\alpha }{\ell }_{\beta },{\nu }_{\alpha }{\overline{\nu }}_{\beta }$. This allows the new Yukawa interactions (responsible for neutrino mass generation) to take small values and therefore avoid the mass degeneracy between the $CP$-even and $CP$-odd inert scalars, unlike the case of the minimal scotogenic model. In contrast to many Majorana DM models, the DM in the SI-scotogenic model couples to the quarks at tree level, and hence the constraint from the direct detection experiments is very important on the space parameter.