Recent works combining neutrino oscillation and cosmological data to determine the neutrino hierarchy found a range of odds in favor of the normal hierarchy. These results arise from differing approaches to incorporating prior knowledge about neutrinos. We develop a hierarchy-agnostic prior and show that the hierarchy cannot be conclusively determined with current data. The determination of the hierarchy is limited by the neutrino mass scale ${\mathrm{\Sigma }}_{\nu }$ measurement. We obtain a target precision of $\sigma ({\mathrm{\Sigma }}_{\nu })=0.014\mathrm{eV}$, necessary for conclusively establishing the normal hierarchy with future data.

We account for particle emission and gravitational radiation from cosmic string loops to determine their effect on the loop distribution and observational signatures of strings. The effect of particle emission is that the number density of loops no longer scales. This results in a high-frequency cutoff on the stochastic gravitational wave background, but we show that the expected cutoff is outside the range of current and planned detectors. Particle emission from string loops also produces a diffuse gamma-ray background that is sensitive to the presence of kinks and cusps on the loops. However, both for kinks and cusps, and with mild assumptions about particle physics interactions, current diffuse gamma-ray background observations do not constrain $G\mu$.

We propose the mean field dynamo model for the generation of strongest magnetic fields, $B\sim 10^{15}\mathrm{G}$, in a neutron star (NS) accounting for the chiral magnetic effect (CME) driven by the shock in a supernova (SN) progenitor of that NS. The temperature jump at a narrow shock front, where an initial magnetic field existing in inflowing matter rises sharply, is the source of the CME that prevails significantly diminishing the CME due to the spin flip through Coulomb collisions in plasma. The growth of the magnetic field just behind the shock given by the instability term $\nabla \times (\alpha \mathbf{B})$ in induction equation stops after a successful SN explosion that throws out the mantle of a protoneutron star. As a result, such an explosion interrupts the transfer of strongly magnetized plasma from the shock onto NS surface and leads to the saturation of the magnetic field. Assuming the rigid protostar rotation, we employ the mean field dynamo, which is similar to the ${\alpha }^2$-dynamo known in the standard magnetohydrodynamics (MHD). The novelty of our model is that ${\alpha }^2$-dynamo is based on concepts of particle physics, applied in MHD, rather than by a mirror asymmetry of convective vortices in the rotating convection.

Primordial black holes (PBHs), as dark matter candidates, have attracted more and more attention as they could be possible progenitors of the heavy binary black holes (BBHs) observed by LIGO/Virgo. Accurately estimating the merger rate of PBH binaries will be crucial to reconstruct the mass distribution of PBHs. It was pointed out the merger history of PBHs may shift the merger rate distribution depending on the mass function of PBHs. In this paper, we use 10 BBH events from LIGO/Virgo O1 and O2 observing runs to constrain the merger rate distribution of PBHs by taking into account the effect of merger history. We perform the analysis by explicitly considering two commonly used PBH mass functions: the power-law and the log-normal ones, respectively. It is found that the second merger process makes a subdominant contribution to the total merger rate, and hence the merger history effect can be safely neglected. We also confirm that the main components of dark matter should not be made of stellar-mass PBHs.

Ultralight particles ($m_a\sim {10}^{-21}–{10}^{-22}\mathrm{eV}$) with axionlike couplings to other particles can be candidates for fuzzy dark matter (FDM) if the axion decay constant $f_a\sim {10}^{17}\mathrm{GeV}$. If a compact star is immersed in such a low-mass axionic potential, it develops a long-range field outside the star. This axionic field is radiated away when the star is in a binary orbit. The orbital period of a compact binary decays mainly due to the gravitational wave radiation, which was confirmed first in the Hulse-Taylor binary pulsar. The orbital period can also decay by radiation of other light particles like axions and axionlike particles (ALPs). For axionic radiation to take place, the orbital frequency of the periodic motion of the binary system should be greater than the mass of the scalar particle which can be radiated. This implies that, for most of the observed binaries, particles with mass $m_a<{10}^{-19}\mathrm{eV}$ can be radiated, which includes FDM particles. In this paper, we consider four compact binary systems—PSR $\mathrm{J}0348+0432$, PSR $\mathrm{J}0737-3039$, PSR $\mathrm{J}1738+0333$, and PSR $\mathrm{B}1913+16$ (Hulse-Taylor binary)—and show that the observations of the decay in orbital period set a bound on the axion decay constant of $f_a\lesssim \mathcal{O}({10}^{11}\mathrm{GeV})$. This implies that fuzzy dark matter cannot couple to gluons.

In the multimessenger astronomy era, accurate sky localization and low latency time of gravitational-wave (GW) searches are keys in triggering successful follow-up observations on the electromagnetic counterpart of GW signals. We, in this work, study the feasibility of adopting a supervised machine learning (ML) method for scoring rank on candidate GW events. We consider two popular ML methods, random forest and neural networks. We observe that the evaluation time of both methods takes tens of milliseconds for $\sim \mathrm{45,000}$ evaluation samples. We compare the classification efficiency between the two ML methods and a conventional low-latency search method with respect to the true positive rate at given false positive rate. The comparison shows that about 10% improved efficiency can be achieved at lower false positive rate $\sim 2\times {10}^{-5}$ with both ML methods. We also present that the search sensitivity can be enhanced by about 18% at $\sim {10}^{-11}\mathrm{Hz}$ false alarm rate. We conclude that adopting ML methods for ranking candidate GW events is a prospective approach to yield low latency and high efficiency in searches for GW signals from compact binary mergers.

We derive, in a manifestly covariant and electromagnetic gauge independent way, the evolution law of the electric field $E^{\alpha }=E{e}^{\alpha }(e^{\alpha }{e}_{\alpha }=1)$, relative to an arbitrary set of instantaneous observers along a null geodesic ray, for an arbitrary Lorentzian spacetime, in the geometrical optics limit of Maxwell’s equations in vacuum. We show that, in general, neither the magnitude $E$ nor the direction $e^{\alpha }$ of the electric field (here interpreted as the observed polarization of light) are parallel transported along the ray. For an extended reference frame around the given light ray, we express the evolution of the direction $e^{\alpha }$ in terms of the frame’s kinematics, proving thereby that its expansion never spoils parallel transport, which bears on the unbiased inference of intrinsic properties of cosmological sources, such as, for instance, the polarization field of the cosmic microwave background (CMB). As an application of the newly derived laws, we consider a simple setup for a gravitational wave (GW) interferometer, showing that, despite the (kinematic) shear induced by the GW, the change in the final interference pattern is negligible since it turns out to be of the order of the ratio of the GW and laser frequencies.

The bulk nuclear matter produced in heavy ion collisions carries a multitude of conserved quantum numbers: electric charge, baryon number, and strangeness. Therefore, the diffusion processes associated with these conserved charges cannot occur independently and must be described in terms of a set of coupled diffusion equations. This physics is implemented by replacing the traditional diffusion coefficients for each conserved charge by a diffusion coefficient matrix, which quantifies the coupling between the conserved quantum numbers. The diagonal coefficients of this matrix are the usual charge diffusion coefficients, while the off-diagonal entries describe the diffusive coupling of the charge currents. In this paper, we show how to calculate this diffusion coefficient matrix from kinetic theory and provide results for a hadron resonance gas and a gas of partons. We further find that the off-diagonal entries can reach similar magnitudes compared to the diagonal entries. In order to provide some insight on the influence that the coupling between the net charge diffusion currents can have on heavy ion observables, we present first results for the diffusive evolution of a hadronic system in a simple $(1+1)\mathrm{D}$-fluid dynamics approach, and study different configurations of the diffusion matrix.

Scattering methods make it possible to compute the effects of renormalized quantum fluctuations on classical field configurations. As a classic example of a topologically nontrivial classical solution, the Abrikosov-Nielsen-Olesen vortex in U(1) Higgs-gauge theory provides an ideal case in which to apply these methods. While physically measurable gauge-invariant quantities are always well behaved, the topological properties of this solution give rise to singularities in gauge-variant quantities used in the scattering problem. In this paper we show how modifications of the standard scattering approach are necessary to maintain gauge invariance within a tractable calculation. We apply this technique to the vortex energy calculation in a simplified model, and show that to obtain accurate results requires an unexpectedly extensive numerical calculation, beyond what has been used in previous work.

We present a realization of the idea that the Higgs boson is mainly a bound state of neutrinos induced by strong four-fermion interactions. The conflicts of this idea with the measured values of the top quark and Higgs boson masses are overcome by introducing, in addition to the right-handed neutrino, a new fermion singlet, which, at low energies, implements the inverse seesaw mechanism. The singlet fermions also develop a scalar bound state that mixes with the Higgs boson. This allows us to obtain a small Higgs boson mass even if the couplings are large, as required in composite scalar scenarios. The model gives the correct masses for the top quark and Higgs boson for compositeness scales below the Planck scale and masses of the new particles above the electroweak scale, so that we obtain naturally a low-scale seesaw scenario for neutrino masses. The theory contains additional scalar particles coupled to the neutral fermions, which could be tested in present and near future experiments.

We analyze a novel signature of the type-II seesaw model—a same-sign tetralepton signal arising from the mixing of neutral Higgs bosons and their subsequent decays to singly and doubly charged Higgs bosons. For this, we consider wide ranges of the triplet vacuum expectation value (vev) and Yukawa couplings that are consistent with the observed neutrino masses and mixing as well as the LHC search limits. We find that a doubly charged Higgs boson with mass around 250 GeV and triplet vev around ${10}^{-4}–{10}^{-2}\mathrm{GeV}$ can give a significantly large number of events through its decay to same-sign $W$ gauge bosons at the high-luminosity LHC with $3000{\mathrm{fb}}^{-1}$ of data. We also pursue the analysis for a future hadron collider with the c.m. energy of 100 TeV. Considering a heavy Higgs boson of around 900 GeV and an intermediate region of the triplet vev, where both same-sign dilepton and gauge boson decays can occur, we identify a limited range of the parameters where the number of same-sign tetralepton events are as large as 1000.

We propose a minimal extension of the standard model of particle physics to accommodate cosmic inflation, dark matter, and light neutrino masses. While the inflationary phase is obtained from a modified chaotic inflation scenario, consistent with the latest cosmology data, the dark matter particle is a fermion singlet that remains out of equilibrium in the early universe. The scalar field that revives the chaotic inflation scenario by suitable modification also assists in generating tiny couplings of dark matter with its mother particle, naturally realizing the nonthermal or freeze-in type dark matter scenario. Interestingly, the same assisting scalar field also helps in realizing tiny Yukawa couplings required to generate the sub–electron volt Dirac neutrino mass from neutrino couplings to the standard model–like Higgs field. The minimality as well as providing a unified solution to all three problems keeps the model predictive at experiments spanning out to all frontiers.

We study two-color QCD with two flavors of Wilson fermion as a function of quark chemical potential $\mu$ and temperature $T$, for two different lattice spacings and two different quark masses. We find that the quarkyonic region, where the behavior of the quark number density and the diquark condensate are described by a Fermi sphere of almost free quarks distorted by a Bardeen-Cooper-Schrieffer gap, extends to larger chemical potentials with decreasing lattice spacing or quark mass. In both cases, the quark number density also approaches its noninteracting value. The pressure at low temperature is found to approach the Stefan–Boltzmann limit from below.

Quark bilinear operators with staple-shaped Wilson lines are used to study transverse-momentum-dependent parton distribution functions (TMDPDFs) from lattice quantum chromodynamics (QCD). Here, the renormalization factors for the isovector operators, including all mixings between operators with different Dirac structures, are computed nonperturbatively in the regularization-independent momentum subtraction scheme for the first time. This study is undertaken in quenched QCD with three different lattice spacings. With Wilson flow applied to the gauge fields in the calculations, the operator mixing pattern due to chiral symmetry breaking with the lattice regularization is found to be significantly different from that predicted by one-loop lattice perturbation theory calculations. These results constitute a critical step toward the systematic extraction of TMDPDFs from lattice QCD.

Interiors of neutron stars are ultradense and may contain a core of deconfined quark matter. Such a core connects to the outer layers smoothly or through a sharp microscopic interface or through an intermediate macroscopic layer of inhomogeneous mixed phases, which is globally neutral but locally contains electrically charged domains. Here I employ a nucleon-meson model under neutron star conditions that shows a first-order chiral phase transition at large densities. In the vicinity of this chiral transition I calculate the free energies of various mixed phases—different “pasta structures”—in the Wigner-Seitz approximation. Crucially, chirally broken nuclear matter and the approximately chirally symmetric phase (loosely interpreted as quark matter) are treated on the same footing. This allows me to compute the interface profiles of bubbles, rods, and slabs fully consistently, taking into account electromagnetic screening effects and without needing the surface tension as an input. I find that the full numerical results tend to disfavor mixed phases compared to a simple steplike approximation used frequently in the literature and that the predominantly favored pasta structure consists of slabs with a surface tension $\mathrm{\Sigma }\simeq 6\mathrm{MeV}/{\mathrm{fm}}^2$.

I present results for top-quark double-differential distributions in transverse momentum and rapidity. Second- and third-order soft-gluon corrections derived from next-to-next-to-leading-logarithm resummation are added to the complete next-to-leading-order result, and the combination is denoted as approximate ${\mathrm{N}}^3\mathrm{LO}$. The corrections are large and they reduce theoretical uncertainties. The theoretical results are in good agreement with recent data from the LHC.

A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell $W$ and $Z$ bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of $\sqrt{s}=13\mathrm{TeV}$ were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of $139{\mathrm{fb}}^{-1}$. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV.

A new generation of experiments is expected to shed light on the elusive parton structure of the bound proton. One of the most promising directions is incoherent deeply virtual Compton scattering, which can provide a tomographic view of the bound proton. The first measurement has been recently performed, using ${}^4\mathrm{He}$ targets at Jefferson Lab. In the work presented here, a rigorous impulse approximation analysis of this process is proposed. As ingredients, state-of-the-art models of the nuclear spectral function and of the parton structure of the struck proton, together with novel scattering amplitudes expressions for a bound moving nucleon, have been used. The overall agreement obtained with the data, good in particular at high values of the photon virtuality, demonstrates the solidity of the framework, which is also suitable for further improvements. It is found that possible big differences between results for the bound proton and those for the free one could be related to kinematical nuclear effects and not to modifications of the parton structure. The analysis demonstrates that the comparison of the results of this approach, based on a conventional description, with future precise data, has the potential to expose exotic quark and gluon effects in nuclei.

We compute the electric dipole moment (EDM) of the deuteron in the holographic QCD model of Witten-Sakai-Sugimoto. Previously, the leading contribution to the EDM of nucleons was computed, finding opposite values for the proton and the neutron, which then cancel each other in the deuteron state. Here we compute the next-to-leading order contribution, which provides a splitting between their absolute value. At large $N_{\mathrm{c}}$ and large ‘t Hooft coupling $\lambda$, nuclei are bound states of almost isolated nucleons. In particular, we find that in this limit the deuteron EDM is given by the splitting between proton and neutron EDMs. Our estimate for the deuteron EDM extrapolated to the physical values of $N_{\mathrm{c}}$, $\lambda$, $M_{\mathrm{KK}}$, and $m_q$ is $d_d=-0.92\times {10}^{-16}\theta e·\mathrm{cm}$. This is consistent, in sign and magnitude, with results found previously in the literature and obtained using completely different methods.