Understanding the properties of dust emission in the microwave domain is an important premise for the next generation of cosmic microwave background (CMB) experiments, devoted to the measurement of the primordial $B$-modes of polarization. In this paper, we compare three solutions to thermal dust emission by the Planck Collaboration [A. Abergel, P. A. R. Ade et al. (Planck Collaboration), Astron. Astrophys. 571, A11 (2014).,R. Adam, P. A. R. Ade et al. (Planck Collaboration), Astron. Astrophys. 594, A10 (2016)., N. Aghanim, M. Ashdown et al. (Planck Collaboration), Astron. Astrophys. 596, A109 (2016).] to point out significant differences between their respective parameters (the spectral index $\beta$, the optical depth $\tau$, and the dust temperature $T_d$). These differences originate from, e.g., the priors on the parameters or the contribution of the cosmic infrared background (CIB). In addition to investigating the angular distributions and statistical properties of each of the $\beta$, $\tau$, and $T_d$-maps for the whole sky, we also compute cross-correlations among the maps, specifically the $\beta -T_d$ and $\tau -T_d$ correlations. All power spectra differ noticeably from each other, which we claim is partly due to the influence of the CIB. Peculiar behavior in the cross-correlations at dust temperatures $\gtrsim 21\mathrm{K}$ supports this claim; the precise differences depend on the particular solutions considered. Finally, by the example of two zones on the sky (the BICEP2 zone and a region around the North Celestial Pole), we show that not only the properties of dust are different in these regions on the sky, but moreover the dust emission products do not agree. Furthermore, it is illustrated that the use of average values for dust parameters in one zone will not necessarily be applicable to another zone. In this context, we therefore recommend pixel-based approaches for future analyses, with less stringent constraints in form of priors, despite its higher computational expenditure, and an inclusion of a CIB treatment, which finally allows for a direction dependent removal of dust foregrounds. The central statement of this brief analysis is that while all available solutions are in rough agreement at $\sim 5\%–20\%$, further progress must be made to match the goals of planned $B$-mode experiments.

We study the process of dark matter particles scattering off ${}^{3,4}\mathrm{He}$ with nuclear wave functions computed using an ab initio many-body framework. We employ realistic nuclear interactions derived from chiral effective field theory at next-to-next-to-leading order (NNLO) and develop an ab initio scheme to compute a general set of different nuclear response functions. In particular, we then perform an accompanying uncertainty quantification on these quantities and study error propagation to physical observables. We find a rich structure of allowed nuclear responses with significant uncertainties for certain spin-dependent interactions. The approach and results that are presented here establish a new framework for nuclear structure calculations and uncertainty quantification in the context of direct and (certain) indirect searches for dark matter.

We examine how future gravitational-wave measurements from merging black holes (BHs) can be used to infer the shape of the black-hole mass function, with important implications for the study of star formation and evolution and the properties of binary BHs. We model the mass function as a power law, inherited from the stellar initial mass function, and introduce lower and upper mass cutoff parametrizations in order to probe the minimum and maximum BH masses allowed by stellar evolution, respectively. We initially focus on the heavier BH in each binary, to minimize model dependence. Taking into account the experimental noise, the mass measurement errors and the uncertainty in the redshift dependence of the merger rate, we show that the mass function parameters, as well as the total rate of merger events, can be measured to $<10\%$ accuracy within a few years of advanced LIGO observations at its design sensitivity. This can be used to address important open questions such as the upper limit on the stellar mass which allows for BH formation and to confirm or refute the currently observed mass gap between neutron stars and BHs. In order to glean information on the progenitors of the merging BH binaries, we then advocate the study of the two-dimensional mass distribution to constrain parameters that describe the two-body system, such as the mass ratio between the two BHs, in addition to the merger rate and mass function parameters. We argue that several years of data collection can efficiently probe models of binary formation, and show, as an example, that the hypothesis that some gravitational-wave events may involve primordial black holes can be tested. Finally, we point out that in order to maximize the constraining power of the data, it may be worthwhile to lower the signal-to-noise threshold imposed on each candidate event and amass a larger statistical ensemble of BH mergers.

In this work we present the cosmological dynamics of interacting dark energy models in the framework of the particle-creation mechanism. The particle-creation mechanism presented here describes the true nonequilibrium thermodynamics of the Universe. In the spatially flat Friedmann-Lemaître-Robertson-Walker universe considered here, the dissipative bulk viscous pressure is due to the nonconservation of particle number. For simplicity, we assume that the creation of perfect-fluid particles is isentropic (adiabatic) and consequently the viscous pressure obeys a linear relationship with the particle-creation rate. Due to the complicated nature of Einstein’s field equations, dynamical systems analysis is performed to understand the cosmological dynamics. We find some interesting cosmological scenarios, like a late-time evolution of the universe dominated by dark energy which could mimic quintessence, a cosmological constant, and a phantom field through a dark-matter-dominated era. We also find a possibility of crossing the phantom divide line which is favored by observations.

We have performed magnetohydrodynamic simulations in general relativity of binary neutron star and binary black hole-neutron star mergers, as well as the magnetorotational collapse of supermassive stars. In many cases the outcome is a spinnng black hole (BH) immersed in a magnetized disk, with a jet emanating from the poles of the BH. While their formation scenarios differ and their BH masses, as well as their disk masses, densities, and magnetic field strengths, vary by orders of magnitude, these features conspire to generate jet Poynting luminosities that all lie in the same, narrow range of $\sim 10^{52\pm 1}\mathrm{erg}{\mathrm{s}}^{-1}$. A similar result applies to their BH accretion rates upon jet launch, which is $\sim 0.1-10M_{\odot }{\mathrm{s}}^{-1}$. We provide a simple model that explains these unanticipated findings. Interestingly, these luminosities reside in the same narrow range characterizing the observed luminosity distributions of over 400 short and long GRBs with distances inferred from spectroscopic redshifts or host galaxies. This result, together with the GRB lifetimes predicted by the model, supports the belief that a compact binary merger is the progenitor of an SGRB, while a massive, stellar magnetorotational collapse is the progenitor of an LGRB.

We study the tidal deformability of bare quark stars and hybrid compact stars composed of a quark-matter core in general relativity, assuming that the deconfined quark matter exists in a crystalline color superconducting phase. We find that taking the elastic property of crystalline quark matter into account in the calculation of the tidal deformability can break the universal I-Love relation discovered for fluid compact stars, which connects the moment of inertia and tidal deformability. Our result suggests that measurements of the moment of inertia and tidal deformability can in principle be used to test the existence of solid quark stars, despite our ignorance of the high-density equation of state. Assuming that the moment of inertia can be measured to 10% level, one can then distinguish a $1.4(1)M_{\odot }$ solid quark star described by our quark-matter equation of state model with a gap parameter $\mathrm{\Delta }=25\mathrm{MeV}$ from a fluid compact star if the tidal deformability can be measured to about 10% (45%) level. On the other hand, we find that the nuclear matter fluid envelope of a hybrid star can screen out the effect of the solid core significantly so that the resulting I-Love relation for hybrid stars still agrees with the universal relation for fluid stars to about 1% level.

Within the standard three-neutrino framework, the absolute neutrino masses and their ordering (either normal, NO, or inverted, IO) are currently unknown. However, the combination of current data coming from oscillation experiments, neutrinoless double beta ($0\nu \beta \beta$) decay searches, and cosmological surveys, can provide interesting constraints for such unknowns in the sub-eV mass range, down to $O({10}^{-1})\mathrm{eV}$ in some cases. We discuss current limits on absolute neutrino mass observables by performing a global data analysis that includes the latest results from oscillation experiments, $0\nu \beta \beta$ decay bounds from the KamLAND-Zen experiment, and constraints from representative combinations of Planck measurements and other cosmological data sets. In general, NO appears to be somewhat favored with respect to IO at the level of $\sim 2\sigma$, mainly by neutrino oscillation data (especially atmospheric), corroborated by cosmological data in some cases. Detailed constraints are obtained via the ${\chi }^2$ method, by expanding the parameter space either around separate minima in NO and IO or around the absolute minimum in any ordering. Implications for upcoming oscillation and nonoscillation neutrino experiments, including $\beta$-decay searches, are also discussed.

We study the leptonic decay of charged pions in a compact star environment. Considering leptons as a degenerated Fermi system, pions are tightly constrained to decay into these particles because their Fermi levels are occupied. Thus, pion decay is only possible through thermal fluctuations. Under these circumstances, pion lifetime is larger and hence can be considered to reach a metastable state. We explore restrictions under which such a metastability is possible. We also study conditions under which pions and leptons already in chemical equilibrium can reach simultaneously the thermal equilibrium, and obtain the neutrino emissivity from metastable pions. Scenarios that favor this metastable state are protoneutron stars.

We study the real-time evolution of an electron influenced by intense electromagnetic fields using the time-dependent basis light-front quantization (tBLFQ) framework. We focus on demonstrating the nonperturbative feature of the tBLFQ approach through a realistic application of the strong coupling QED problem, in which the electromagnetic fields are generated by an ultrarelativistic nucleus. We calculate transitions of an electron influenced by such electromagnetic fields and we show agreement with light-front perturbation theory when the atomic number of the nucleus is small. We compare tBLFQ simulations with perturbative calculations for nuclei with different atomic numbers, and obtain the significant higher-order contributions for heavy nuclei. The simulated real-time evolution of the momentum distribution of an electron evolving inside the strong electromagnetic fields exhibits significant nonperturbative corrections compared to light-front perturbation theory calculations. The formalism used in this investigation can be extended to QCD problems in heavy ion collisions and electron ion collisions.

We describe the unitarity approach for the numerical computation of two-loop integral coefficients of scattering amplitudes. It is well known that the leading propagator singularities of an amplitude’s integrand are related to products of tree amplitudes. At two loops, Feynman diagrams with doubled propagators appear naturally, which lead to subleading pole contributions. In general, it is not known how these contributions can be directly expressed in terms of a product of on-shell tree amplitudes. We present a universal algorithm to extract these subleading pole terms by releasing some of the on-shell conditions. We demonstrate the new approach by numerically computing two-loop four-gluon integral coefficients.

By making use of the chiral kinetic theory in the relaxation-time approximation, we derive an Israel-Stewart type formulation of the hydrodynamic equations for a chiral relativistic plasma made of neutral particles (e.g., neutrinos). The effects of chiral asymmetry are captured by including an additional continuity equation for the axial charge, as well as the leading-order quantum corrections due to the spin of particles. In a formulation of the chiral kinetic theory used, we introduce a symmetric form of the energy-momentum tensor that is suitable for the description of a weakly nonuniform chiral plasma. By construction, the energy and momentum are conserved to the same leading order in the Planck constant as the kinetic equation itself. By making use of such a chiral kinetic theory and the Chapman-Enskog approach, we obtain a set of second-order dissipative hydrodynamic equations. The effects of the fluid vorticity and velocity fluctuations on the dispersion relations of chiral vortical waves are analyzed.

We study the transport properties of strongly interacting matter in the context of ultrarelativistic heavy ion collision experiments. We calculate the transport coefficients viz. shear viscosity ($\eta$) and electrical conductivity (${\sigma }_{\mathrm{el}}$) of the quark gluon plasma phase in the presence of momentum anisotropy arising from different expansion rates of the medium in longitudinal and transverse direction. We solve the relativistic Boltzmann kinetic equation in relaxation time approximation to calculate the shear viscosity and electrical conductivity. The calculation are performed within the quasiparticle model to estimate these transport coefficients and discuss the connection between them. We also compare the electrical conductivity results calculated from the quasiparticle model with the ideal case. We compare our results with the corresponding results obtained in different lattice as well as model calculations.

In this work we present a new computation of the lepton flavor violating Higgs boson decays that are generated radiatively to one-loop from heavy right-handed neutrinos. We work within the context of the inverse seesaw model with three ${\nu }_R$ and three extra singlets $X$, but the results could be generalized to other low scale seesaw models. The novelty of our computation is that it uses a completely different method by means of the mass insertion approximation which works with the electroweak interaction states instead of the usual 9 physical neutrino mass eigenstates of the inverse seesaw model. This method also allows us to write the analytical results explicitly in terms of the most relevant model parameters, that are the neutrino Yukawa coupling matrix $Y_{\nu }$ and the right-handed mass matrix $M_R$, which is very convenient for a phenomenological analysis. This $Y_{\nu }$ matrix, being generically nondiagonal in flavor space, is the only one responsible for the induced charged lepton flavor violating processes of our interest. We perform the calculation of the decay amplitude up to order $\mathcal{O}(Y_{\nu }^2+Y_{\nu }^4)$. We also study numerically the goodness of the mass insertion approximation results. In the last part we present the computation of the relevant one-loop effective vertex $H{\ell }_i{\ell }_j$ for the lepton flavor violating Higgs decay which is derived from a large $M_R$ mass expansion of the form factors. We believe that our simple formula found for this effective vertex can be of interest for other researchers who wish to estimate the $H\to {\ell }_i{\overline{\ell }}_j$ rates in a fast way in terms of their own preferred input values for the relevant model parameters $Y_{\nu }$ and $M_R$.

In twin Higgs models, a discrete ${\mathbb{Z}}_2$ symmetry between the standard model Higgs and the twin Higgs is introduced to address the hierarchy problem. In this work, we propose another discrete symmetry in twin Higgs: the $T$ parity, which maps the twin Higgs quadruplet into its mirror copy. The $T$ parity brings us a whole group of $T$-odd particles, and leads to a promising dark matter candidate. We present one realization of the $T$-parity twin Higgs scenario by implementing the $SU(2{)}_L\times SU(2{)}_R\times U(1{)}_1\times U(1{)}_2$ gauge symmetry in the left-right twin Higgs model. In this specific setup, the $T$-odd $U(1)$ gauge boson could be the dark matter candidate, and the $T$-odd particles have very distinct and interesting phenomenology.

According to the standard model, the Cabibbo-favored (CF) decays are $CP$ conserved at tree level. Observation of any finite $CP$ asymmetry can be received as a signal of new physics. In CF charm meson decays, $D^0\to K^{-}{\pi }^{+}$ and $D^{+}\to K_s^0{\pi }^{+}$, the following experimental values for their $CP$ asymmetry are reported, respectively: ($0.3\pm 0.7$)% and ($-0.41\pm 0.09$)%. The value of the later can be attributed to the mixing of $K^0$ and $\overline{K^0}$, however, its contribution is about ($-0.332\pm 0.006$)%. In this paper, we use these experimental results to constrain the unparticle stuff as a new physics which may contribute to these $CP$ asymmetries.

We investigate single- and double-$h$, the discovered Standard-Model- (SM) like Higgs boson, production at future $e^{+}{e}^{-}$ colliders in composite 2-Higgs doublet models (C2HDMs) and elementary 2-Higgs doublet models (E2HDMs) with a softly broken $Z_2$ symmetry. We first survey their parameter spaces allowed by theoretical bounds from perturbative unitarity and vacuum stability as well as by future data at the Large Hadron Collider with an integrated luminosity up to $3000{\mathrm{fb}}^{-1}$ under the assumption that no new Higgs boson is detected. We then discuss how different the cross sections can be between the two scenarios when ${\kappa }_V$, the $hVV$ ($V=W^{\pm },Z$) coupling normalized to the SM value, is taken to be the same value in both scenarios. We find that if ${\kappa }_V^2$ is found to be, e.g., 0.98, then the cross sections in C2HDMs with $f$ (the compositeness scale) in the TeV region can be maximally changed to be about $-15\%$, $-18\%$, $-50\%$ and $-35\%$ for the $e^{+}{e}^{-}\to t\overline{t}h$, $e^{+}{e}^{-}\to Zhh$, $e^{+}{e}^{-}\to e^{+}{e}^{-}hh$ and $e^{+}{e}^{-}\to t\overline{t}hh$ processes, respectively, with respect to those in E2HDMs. Thus, a future electron-positron collider has the potential to discriminate between E2HDMs and C2HDMs, even when only $h$ event rates are measured.

We examine lepton flavor violating (LFV) interactions for heavy right-handed neutrinos that exist in most of the standard model extensions that address dark matter (DM) and neutrino mass at the loop level. In order to probe the collider effect of these LFV interactions, we impose the assumption that the model parameters give the right values of the DM relic density and fulfill the constraints from the LFV processes ${\ell }_{\alpha }\to {\ell }_{\beta }\gamma$ and ${\ell }_{\alpha }\to 3{\ell }_{\beta }$. We also investigate the possibility of probing these interactions, and hence the right-handed neutrino, at leptonic colliders through different final state signatures.

In the context of a left-right symmetric model, we introduce one full generation of vectorlike lepton doublets (both left- and right-handed) together with their mirror doublets. We show that the lightest vectorlike neutrino in the model is right-handed, and can serve as the dark matter candidate. We find that the relic density as well as the direct and indirect DM detection bounds are satisfied for a large range of the parameter space of the model. In accordance with the parameter space, we then explore the possibility of detecting signals of the model at both the LHC and the ILC, in the pair production of the associated vectorlike charged leptons which decay into final states including dark matter. A comprehensive analysis of signal and backgrounds shows that the signals at the ILC, especially with polarized beams, are likely to be visible for light vectorlike leptons, even with low luminosity, rendering our model highly predictable and experimentally testable.

A common problem in lattice QCD simulations on the torus is the extremely long autocorrelation time of the topological charge when one approaches the continuum limit. The reason is the suppressed tunneling between topological sectors. The problem can be circumvented by replacing the torus with a different manifold, so that the connectivity of the configuration space is changed. This can be achieved by using open boundary conditions on the fields, as proposed earlier. It has the side effect of breaking translational invariance strongly. Here we propose to use a nonorientable manifold and show how to define and simulate lattice QCD on it. We demonstrate in quenched simulations that this leads to a drastic reduction of the autocorrelation time. A feature of the new proposal is that translational invariance is preserved up to exponentially small corrections. A Dirac fermion on a nonorientable manifold poses a challenge to numerical simulations: the fermion determinant becomes complex. We propose two approaches to circumvent this problem.

When the multiplicities of particles produced in heavy-ion collisions are fitted to the hadron-resonance-gas model, excluded-volume effects play a significant role. In this work, we study the impact of such effects on the equation of state of pure Yang-Mills theory at low temperatures, comparing the predictions of the statistical model with lattice results. In particular, we present a detailed analysis of the SU(2) and SU(3) Yang-Mills theories: we find that, for both of them, the best fits to the equilibrium thermodynamic quantities are obtained when one assumes that the volume of different glueball states is inversely proportional to their mass. The implications of these findings for QCD are discussed.