We study the tunneling probability of a massive ($m_w$) uncharged scalar packet out from a near-extremal, static charged black hole (with mass $M$ and charge $Q\lesssim M$). We show that there is indeed a net probability that a massive uncharged particle tunnels out from the black hole so that the final state (with new mass $M^{\prime }\equiv M-m_w<Q$) does violate the cosmic censorship conjecture. Nevertheless, the typical time for such a black hole to discharge (i.e., to absorb charge $-Q$ from its surroundings and then become neutral) is much smaller than the tunneling time; therefore, the violation is never attained in practice. Even for a completely isolated black hole (should it exist), the standard time dilation near the horizon stretches the typical violation time scale to unobservable values.

We propose a one-parameter extension to $\mathrm{\Lambda }\mathrm{CDM}$, expected to strongly affect cosmological tensions. An effective dark radiation component in the early Universe redshifts away as hot dark matter, then quintessence, tracking the dominant equation-of-state parameter and leaving a falsifiable torsion field in the current epoch. This picture results from a new Poincaré gauge theory (PGT), one of the most promising among the latest batch of 58 PGTs found to be both power-counting renormalizable and free from ghosts and tachyons. We systematically categorize the cosmologies of 33 of these PGTs, as special cases of the most general parity-preserving, Ostrogradsky-stable PGT with a purely Yang-Mills action. The theory we consider contains two propagating massless gravitons, which may be $J^P=2^{+}$ (long-range gravitation and gravitational waves). A conspiracy among the coupling constants eliminates the spatial curvature $k\in \{\pm 1,0\}$ from the field equations. We show that this “$k$-screening” is not restricted to conformal gravity theories. The flat Friedmann equations are then emergent, with potentially tension-resolving freedom at the early scale-invariant epoch that reliably gives way to an attractorlike state of modern $\mathrm{\Lambda }\mathrm{CDM}$ evolution. We compare with related theories and promising special cases, such as $k$-screened theories with negative-definite effective $k$, and more traditional theories with effective $\mathrm{\Lambda }$ and a $J^P=0^{-}$ massive graviton (dark matter candidate). As a bonus, we analyze similarly constrained actions in the new extended Weyl gauge theory (eWGT). We show that in cosmology, PGT and eWGT span exactly the same classical phenomenology up to a linear map between their coupling constants, hinting at a deeper relationship between the two.

Understanding the origin of fast radio bursts (FRBs) is a central unsolved problem in astrophysics that is severely hampered by their poorly determined distance scale. Determining the redshift distribution of FRBs appears to require arcsecond angular resolution, in order to associate FRBs with host galaxies. In this paper, we forecast prospects for determining the redshift distribution without host galaxy associations, by cross-correlating FRBs with a galaxy catalog such as the SDSS photometric sample. The forecasts are extremely promising: a survey such as CHIME/FRB that measures catalogs of $\sim {10}^3$ FRBs with few-arcminute angular resolution can place strong constraints on the FRB redshift distribution, by measuring the cross-correlation as a function of galaxy redshift $z$ and FRB dispersion measure $D$. In addition, propagation effects from free electron inhomogeneities modulate the observed FRB number density, either by shifting FRBs between dispersion measure (DM) bins or through DM-dependent selection effects. We show that these propagation effects, coupled with the spatial clustering between galaxies and free electrons, can produce FRB-galaxy correlations that are comparable to the intrinsic clustering signal. Such effects can be disentangled based on their angular and $(z,D)$ dependence, providing an opportunity to study not only FRBs but also the clustering of free electrons.

A future detection of the stochastic gravitational wave background (SGWB) with gravitational wave (GW) experiments is expected to open a new window on early universe cosmology and on the astrophysics of compact objects. In this paper we study SGWB anisotropies, that can offer new tools to discriminate between different sources of GWs. In particular, the cosmological SGWB inherits its anisotropies both (i) at its production and (ii) during its propagation through our perturbed universe. Concerning (i), we show that it typically leads to anisotropies with order one dependence on frequency. We then compute the effect of (ii) through a Boltzmann approach, including contributions of both large-scale scalar and tensor linearized perturbations. We also compute for the first time the three-point function of the SGWB energy density, which can allow one to extract information on GW non-Gaussianity with interferometers. Finally, we include nonlinear effects associated with long wavelength scalar fluctuations, and compute the squeezed limit of the 3-point function for the SGWB density contrast. Such limit satisfies a consistency relation, conceptually similar to that found in the literature for the case of cosmic microwave background perturbations.

During inflation, scalar fields with masses less than the Hubble scale acquire vacuum expectation values (VEVs) via stochastic processes driven by quantum fluctuations. For nearly massless spectator scalars transforming nontrivially under a continuous symmetry group, we demonstrate that the evolution of the VEV depends on the dimensionality of the scalar field space. Fields in larger representations both attain larger vacuum expectation values and converge more rapidly to equilibrium. We present an argument demonstrating how this higher-dimensional evolution can be obtained in unitary gauge for fields transforming under local symmetries with a mass gap that is small compared to the Hubble scale. Finally, we show that accounting for the full number of degrees of freedom in the Standard Model Higgs multiplet tightens Higgs stability constraints on the inflationary scale at the percent level and has more dramatic consequences for both the VEV and the energy stored in the Higgs field after inflation.

The Fermi Large Area Telescope has observed an excess of $\sim \mathrm{GeV}$ energy gamma rays from the center of the Milky Way, which may arise from near-thermal dark matter annihilation. Firmly establishing the dark matter origin for this excess is however complicated by challenges in modeling diffuse cosmic-ray foregrounds as well as unresolved astrophysical sources, such as millisecond pulsars. Non-Poissonian template fitting (NPTF) is one statistical technique that has previously been used to show that at least some fraction of the GeV excess is likely due to a population of dim point sources. These results were recently called into question by Leane and Slatyer (2019), who showed that a synthetic dark matter annihilation signal injected on top of the real Fermi data is not recovered by the NPTF procedure. In this work, we perform a dedicated study of the Fermi data and explicitly show that the central result of Leane and Slatyer (2019) is likely driven by the fact that their choice of model for the Galactic foreground emission does not provide a sufficiently good description of the data. We repeat the NPTF analyses using a state-of-the-art model for diffuse gamma-ray emission in the Milky Way and introduce a novel statistical procedure, based on spherical-harmonic marginalization, to provide an improved description of the Galactic diffuse emission in a data-driven fashion. With these improvements, we find that the NPTF results continue to robustly favor the interpretation that the Galactic Center excess is due, in part, to unresolved astrophysical point sources across the analysis variations that we have explored.

We correct 5 typos and add important information for our Phys. Rev. D 83, 094004 (2011) article. The solutions to the equations obtained using QCD sum rules, the results, and the conclusions in our original article are not modified.

We investigate the nonequilibrium evolution of the quark-meson model using two-particle irreducible effective action techniques. Our numerical simulations, which include the full dynamics of the order parameter of chiral symmetry, show how the model thermalizes into different regions of its phase diagram. In particular, by studying quark and meson spectral functions, we shed light on the real-time dynamics approaching the crossover transition, revealing, e.g., the emergence of light effective fermionic degrees of freedom in the infrared. At late times in the evolution, the fluctuation-dissipation relation emerges naturally among both meson and quark degrees of freedom, confirming that the simulation approaches thermal equilibrium.

The $B_c$ meson pair, including pairs of pseudoscalar states and vector states, productions in high energy photon-photon interaction are investigated at the next-to-leading order (NLO) accuracy in the nonrelativistic quantum chromodynamics factorization formalism. The corresponding cross sections at the future $e^{+}{e}^{-}$ colliders with $\sqrt{s}=250\mathrm{GeV}$ and 500 GeV are evaluated. Numerical result indicates that the inclusion of the NLO corrections shall greatly suppress the scale dependence and enhance the prediction reliability. In addition to the phenomenological meaning, the NLO QCD calculation of this process subjects to certain technical issues, which are elucidated in detail and might be applicable to other relevant investigations.

We study the interference between the amplitudes for $gg\to X\to gg$, where $X$ is a new heavy digluon resonance, and the QCD background $gg\to gg$, at the Large Hadron Collider. The interference produces a large low-mass tail and a deficit of events above the resonance mass, compared to the naive pure-resonance peak. For a variety of different resonance quantum numbers and masses, we evaluate the signal-background interference contribution at leading order, including showering, hadronization, and detector effects. The resulting new physics dijet mass distribution may have a shape that appears, after QCD background fitting and subtraction, to resemble an enhanced peak, a shelf, a peak/dip, or even a pure dip. We argue that the true limits on new digluon resonances are likely to differ significantly from the limits obtained when interference is neglected, especially if the branching ratio to $gg$ is less than 1.

It is well known that the standard model of electroweak interactions rests on a metastable vacuum. This can be fixed only by means of new physics. Presently neutrino physics provides the most intriguing framework to formulate new physics. This is so because, in addition to the problem with lightness for the active standard neutrinos, current MiniBooNE experimental results may indicate that sterile neutrinos exist and are light, too. In this case, it is reasonable to expect that the framework that yields light active and sterile neutrinos could stabilize the vacuum, too. To achieve this goal, we consider an extension of the standard model which involves new fermions in the form of right-handed neutrinos (${\nu }_R$) and new scalars in the form of triplets ($\mathrm{\Delta }$) and singlets ($\sigma$). Within this framework, tiny masses are obtained when we consider that lepton number is spontaneously broken at low-energy scale, which means that $\mathrm{\Delta }$ and $\sigma$ both develop very small vacuum expectation values. We investigate whether this setting leads to a stable vacuum. For this, we obtain the whole set of conditions over the quartic terms of the potential that ensures that the model is bounded from below and evaluate the renormalization group equation of the self-coupling of the Higgs. We show that in such a scenario the quartic coupling $\kappa$ of the interaction (${\mathrm{\Phi }}^T\mathrm{\Delta }\mathrm{\Phi }\sigma +\mathrm{H}.\mathrm{c}.$), where $\mathrm{\Phi }$ is the standard Higgs doublet, is responsible for the stability of the electroweak vacuum up to Planck scale. We also extract constraints over the parameters of the potential by means of lepton flavor violating processes and from invisible decay of the standardlike Higgs.

In this work, we present a solution to the persistent tensions in the decay observables $R_{D^{(*)}}$ and $R_{K^{(*)}}$ by introducing a $SU(2{)}_L$ doublet and a $SU(2{)}_L$ triplet scalar leptoquarks (LQs) that reside at the TeV energy scale. Neutrinos that remain massless in the Standard Model receive naturally small masses at one-loop level via the propagation of the same LQs inside the loop. Such a common origin of apparently disjoint phenomenological observations is appealing, and we perform a comprehensive analysis of this setup. We identify the minimal Yukawa textures required to accommodate these flavor anomalies and to successfully incorporate neutrino oscillation data while being consistent with all experimental constraints. This scenario has the potential to be tested at the experiments by the future improved measurements in the lepton flavor violating processes. Furthermore, proper explanations of these flavor anomalies predict TeV scale LQs that are directly accessible at the LHC.

We consider the effect on early Universe cosmology of the dark photon associated with the gauging of $U(1{)}_{T3R}$, a symmetry group under which only right-handed Standard Model fermions transform nontrivially. We find that cosmological constraints on this scenario are qualitatively much more severe than on other well-studied cases of a new $U(1)$ gauge group, because the dark photon couples to chiral fermions. In particular, the dark photon of $U(1{)}_{T3R}$ is always produced and equilibrates in the early Universe, no matter how small the gauge coupling, unless the symmetry-breaking scale is extremely large. This occurs because, no matter how the weak the coupling, the Goldstone mode (equivalently, the longitudinal polarization) does not decouple. As a result, even the limit of an extremely light and weakly coupled dark photon of $U(1{)}_{T3R}$ is effectively ruled out by cosmological constraints, unless the symmetry-breaking scale is extremely large. We also discuss the possibility of ameliorating the Hubble tension in this model.

We provide a simple UV theory for Dirac dark matter with a massless Abelian gauge boson. We introduce a single fermion transforming as the 16 representation in the ${\mathrm{SO}(10)}^{\prime }$ gauge group, which is assumed to be spontaneously broken to $\mathrm{SU}(5{)}^{\prime }\times \mathrm{U}(1{)}^{\prime }$. The ${\mathrm{SU}(5)}^{\prime }$ gauge interaction becomes strong at an intermediate scale, and then we obtain a light composite Dirac fermion with ${\mathrm{U}(1)}^{\prime }$ gauge interaction at a low-energy scale. Its thermal relic can explain the observed amount of dark matter consistently with other cosmological and astrophysical constraints. The dark matter mass and ${\mathrm{U}(1)}^{\prime }$ fine-structure constant are predicted to be 600–700 GeV and $(2.5–2.9)\times {10}^{-2}$, respectively. We discuss that a nonzero kinetic mixing between the ${\mathrm{U}(1)}^{\prime }$ gauge boson and the hypercharge gauge boson is allowed and the temperature of the visible sector and the dark matter sector can be equal to each other.

Implications of supersymmetrizing the clockwork axions are studied. Supersymmetry ensures that the saxions and axinos have the same pattern of the coupling hierarchy as the clockwork axions. If we assume supersymmetry breaking is universal over the clockwork sites, the coupling structure is preserved, while the mass orderings of the saxions and axinos can differ depending on the supersymmetry breaking scale. While the massive saxions and axions quickly decay, the lightest axino can be stable and, thus, a dark matter candidate. The relic abundance of the axino dark matter from thermal production is mostly determined by decays of the heavier axinos in the normal mass ordering. This exponentially enhances the thermal yield compared to the conventional axino scenarios. Some cosmological issues are discussed.

We discuss the possibility to distinguish between Dirac and Majorana neutrinos in the context of the minimal gauge theory for neutrino masses, the $B-L$ gauge extension of the Standard Model. We revisit the possibility to observe lepton number violation at the Large Hadron Collider and point out the importance of the decays of the new gauge boson to discriminate between the existence of Dirac or Majorana neutrinos.

Above a pseudocritical temperature of chiral symmetry restoration $T_c$, the energy and the pressure are very far from the quark-gluon-plasma limit (i.e., ideal gas of free quarks and gluons). At the same time, very soon above $T_c$, fluctuations of conserved charges behave as if quarks were free particles. Within the $T_c-3T_c$ interval, a chiral-spin symmetry emerges in QCD which is not consistent with free quarks and suggests that degrees of freedom are chirally symmetric quarks bound into the color-singlet objects by the chromoelectric field. Here we analyze temporal and spatial correlators in this interval and demonstrate that they indicate simultaneously the chiral-spin symmetry as well as the absence of the interquark interactions in channels constrained by a current conservation. The latter channels are responsible for both fluctuations of conserved charges and for dileptons. Assuming that an $SU(2{)}_{\text{color}}$ subgroup of $SU(3{)}_{\text{color}}$ is deconfined soon above $T_c$ but confinement persists in $SU(3{)}_{\text{color}}/SU(2{)}_{\text{color}}$ in the interval $T_c-3T_c$, we are able to reconcile all empirical facts listed above.

We perform a first calculation for the unpolarized parton distribution function of the ${\mathrm{\Delta }}^{+}$ baryon using lattice QCD simulations within the framework of large momentum effective theory. Two ensembles of $N_f=2+1+1$ twisted mass fermions are utilized with a pion mass of 270 and 360 MeV, respectively. The baryon, which is treated as a stable single-particle state, is boosted with momentum $P_3$ with values $\{0.42,0.83,1.25\}\mathrm{GeV}$, and we utilize momentum smearing to improve the signal. The unpolarized parton distribution function of ${\mathrm{\Delta }}^{+}$ is obtained using a nonperturbative renormalization and a one-loop formula for the matching, with encouraging precision. In particular, we compute the $\overline{d}(x)-\overline{u}(x)$ asymmetry and compare it with the same quantity in the nucleon, in a first attempt towards resolving the physical mechanism responsible for generating such asymmetry.

Recently LHCb reported the discovery of four extremely narrow excited ${\mathrm{\Omega }}_b$ baryons decaying into ${\mathrm{\Xi }}_b^0{K}^{-}$. We interpret these baryons as bound states of a $b$-quark and a $P$-wave $ss$-diquark. For such a system there are exactly five possible combinations of spin and orbital angular momentum. We predict two of spin $1/2$, two of spin $3/2$, and one of spin $5/2$, all with negative parity. We favor identifying the observed states as those with spins $1/2$ and $3/2$, and give a range of predicted masses for the one with spin $5/2$. We update earlier predictions for these states based on the five narrow excited ${\mathrm{\Omega }}_c$ states reported by LHCb. An alternative picture of the states in which one of $J=1/2$ is extremely wide and hence not seen by LHCb is discussed.

We investigate the $\sigma$ and $\rho$ coupling constants for the $DD$ and $D^{*}{D}^{*}$ interactions, based on correlated $2\pi$ exchange in the $DD$ and $D^{*}{D}^{*}$ interactions. Starting from the $D\overline{D}\to \pi \pi$ and $D^{*}{\overline{D}}^{*}\to \pi \pi$ amplitudes derived in the pseudophysical region ($4m_{\pi }^2\le t\le 52m_{\pi }^2$) with the $S$- and $P$-wave $2\pi$ correlations considered, we obtain the spectral functions for the $DD\to DD$ and $D^{*}{D}^{*}\to D^{*}{D}^{*}$ amplitude with correlated $S$- and $P$-wave $2\pi$ exchanges. Using the pole approximation, we estimate the $DD\sigma$, $DD\rho$, $D^{*}{D}^{*}\sigma$, and $D^{*}{D}^{*}\rho$ coupling constants. We extended phenomenologically the present results to the region in $t\le 0$ and compare them with those from lattice QCD. The results are also compared with those of other models. We also present the results of the $BB\sigma$, $BB\rho$, $B^{*}{B}^{*}\sigma$, and $B^{*}{B}^{*}\rho$ coupling constants. We observe that it is unlikely that the $\sigma$ and $\rho$ coupling constants for the $B$ and $B^{*}$ mesons are the same as those for the $D$ and $D^{*}$ mesons. On the contrary, they are quite larger than those for the charmed mesons.