We consider the constraints on the fraction of dark matter in the universe in the form of primordial black holes taking into account the crucial role of accretion which may change both their mass and mass function. We show that accretion may drastically weaken the constraints at the present epoch for primordial black holes with masses larger than a few solar masses.

We consider $f(R)$ gravity theories which unify $R^n$ inflation and dark energy models. First, from the final Planck data of the cosmic microwave background, we obtain a condition, $1.977<n<2.003$. Next, under this constraint, we investigate local-gravity tests for three models. We find that the $R^n$ term can dominate over the dark energy term even at the Earth’s curvature scale, contrary to intuition; however, the $R^n$ term does not relax or tighten the constraints on the three models.

We calculate the two loop correction to the quark 2-point function with the nonzero momentum insertion of the flavor singlet axial vector current at the fully symmetric subtraction point for massless quarks in the modified minimal subtraction ($\overline{\mathrm{MS}}$) scheme. The Larin method is used to handle ${\gamma }^5$ within dimensional regularization at this loop order ensuring that the effect of the chiral anomaly is properly included within the construction.

We use $\overline{p}p$ and $e^{+}{e}^{-}$ annihilation data to further strengthen lower bounds on the partial lifetimes for the baryon-number-violating dinucleon decays $nn\to e^{+}{e}^{-}$ and $nn\to {\mu }^{+}{\mu }^{-}$. These bounds are of interest since baryon number violation is expected to occur in nature and is predicted in many theories beyond the Standard Model.

The phase diagram and the location of the critical endpoint (CEP) of lattice QCD with unimproved staggered fermions on a $N_t=4$ lattice was determined fifteen years ago with the multiparameter reweighting method by studying Fisher zeros. We first reproduce the old result with an exact algorithm (not known at the time) and with statistics larger by an order of magnitude. As an extension of the old analysis we introduce stout smearing in the fermion action in order to reduce the finite lattice spacing effects. First we show that increasing the smearing parameter $\rho$ the crossover at $\mu =0$ gets weaker, i.e., the leading Fisher zero gets farther away from the real axis. Furthermore as the chemical potential is increased the overlap problem gets severe sooner than in the unimproved case, therefore shrinking the range of applicability of the method. Nevertheless certain qualitative features remain, even after introducing the smearing. Namely, at small chemical potentials the Fisher zeros first get farther away from the real axis and later at around $a{\mu }_q=0.1–0.15$ they start to get closer, i.e., the crossover first gets weaker and later stronger as a function of $\mu$. However, because of the more severe overlap problem the CEP is out of reach with the smeared action.

Using a recently proposed method [Y. Meng, C. Liu, and K. L. Zhang, arXiv:1910.11597v3], we study the two-photon decay rate of ${\eta }_c$ using two $N_f=2$ twisted mass gauge ensembles with lattice spacings 0.067 fm and 0.085 fm. The results obtained from these two ensembles can be extrapolated in a naive fashion to the continuum limit, yielding a result that is consistent with the experimental one within two standard deviations. To be specific, we obtain the results for two-photon decay of ${\eta }_c$ as $\mathcal{B}({\eta }_c\to 2\gamma )=1.29(3)(18)\times {10}^{-4}$ where the first error is statistical and the second is our estimate for the systematic error caused by the finite lattice spacing. It turns out that Ward identity for the vector current is of vital importance within this new method. We verify that the Ward identity is violated for local current with a finite lattice spacing, however it will be restored after the continuum limit is taken.

Experimental checks of the second row unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix involve extractions of the matrix element $V_{cd}$, which may be obtained from semileptonic decay rates of $D$ to $\pi$. These decay rates are proportional to hadronic form factors which parametrize how the quark $c\to d$ transition is realized in $D\to \pi$ meson decays. The form factors cannot yet be analytically computed over the whole range of available momentum transfer $q^2$, but can be parametrized with a varying degree of model dependency. We propose analysis of the form factor shapes using a system of artificial neural networks trained from experimental pseudodata and averaged together to predict their shapes with a prescribed uncertainty. We comment on the parameters of several commonly-used model parametrizations of semileptonic form factors. We extract shape parameters and use unitarity to bound the form factor at a given $q^2$, which then allows us to bound the CKM matrix element $|V_{cd}|$.

The bottom-charmed meson spectrum is studied via an effective version of the Coulomb gauge QCD Hamiltonian. The Tamm-Dancoff approximation is employed to estimate the energies of the low-lying and radial-excited $B_c$ states with quantum numbers $J^P=0^{-},0^{+},1^{-},1^{+},2^{+},2^{-}$. In particular, we analyze the effects of incorporating an effective transverse hyperfine interaction and spin mixing. The Regge trajectories and hyperfine splitting of both $S$- and $P$-wave states are also examined. The numerical results are compared with available experimental data and the theoretical predictions of other models.

The addition of $SU(2{)}_L$ triplet fermions of zero hypercharge with the Standard Model (SM) helps to explain the origin of the neutrino mass by the so-called seesaw mechanism. Such a scenario is commonly known as the type-III seesaw model. After the electroweak symmetry breaking, the mixings between the light and heavy mass eigenstates of the neutral leptons are developed and play important roles in the study of the charged and neutral multiplets of the triplet fermions at the colliders. In this article, we study such interactions to produce these multiplets of the triplet fermion at the electron-positron and electron-proton colliders at different center-of-mass energies. We focus on the heavy triplets, for example, having mass in the TeV scale so that their decay products including the SM, the gauge bosons, or the Higgs boson can be sufficiently boosted, leading to a fat jet. Hence, we probe the mixing between light-heavy mass eigenstates of the neutrinos and compare the results with the bounds obtained by the electroweak precision study.

The PHENIX experiment at the Relativistic Heavy Ion Collider has measured the longitudinal double spin asymmetries, $A_{LL}$, for charged pions at midrapidity ($|\eta |<0.35$) in longitudinally polarized $p+p$ collisions at $\sqrt{s}=510\mathrm{GeV}$. These measurements are sensitive to the gluon spin contribution to the total spin of the proton in the parton momentum fraction $x$ range between 0.04 and 0.09. One can infer the sign of the gluon polarization from the ordering of pion asymmetries with charge alone. The asymmetries are found to be consistent with global quantum-chromodynamics fits of deep-inelastic scattering and data at $\sqrt{s}=200\mathrm{GeV}$, which show a nonzero positive contribution of gluon spin to the proton spin.

We propose that the definition of holographic subregion complexity needs a slight modification for supergravity solutions with warped anti–de Sitter (AdS) factors. Such warp factors can arise due to the nontrivial dilaton profile, for example, in ${\mathrm{AdS}}_6$ solutions of type IIA supergravity. This modified definition ensures that the universal piece of the holographic subregion complexity is proportional to that of the holographic entanglement entropy, as is the case for supergravity solutions without warp factors. This also means that the leading behavior at large $N$ is the same for both these quantities, as we show for some well-known supergravity solutions (with and without warp factors) in various dimensions. We also show that this relation between the universal pieces suggests “universal” relations between the field theoretical analogue of holographic subregion complexity and the sphere partition function or Weyl $a$-anomaly in odd or even dimensions, respectively.

Black holes found in binaries move at very high velocities relative to our own reference frame and can accelerate due to the emission of gravitational radiation. Here, we investigate the numerical stability and late-time behavior of linear scalar perturbations in accelerating black holes described by the $C$-metric. We identify a family of quasinormal modes associated with the photon surface and a brand new family of purely imaginary modes associated with the boost parameter of the accelerating black hole spacetime. When the accelerating black hole is charged, we find a third family of modes which dominates the ringdown waveform near extremality. Our frequency- and time-domain analysis indicates that such spacetimes are stable under scalar fluctuations, while the late-time behavior follows an exponential decay law, dominated by quasinormal modes. This result is in contrast with the common belief that such perturbations, for black holes without a cosmological constant, always have a power-law cutoff. In this sense, our results suggest that the asymptotic structure of black hole backgrounds does not always dictate how radiative fields behave at late times.

We study the Hawking flux from a black hole with soft hair by the anomaly cancellation method proposed by Robinson and Wilczek. Unlike the earlier studies considering the black hole with linear supertranslation hair, our study takes into account the supertranslation hair to the quadratic order, which then yields the angular dependent horizon. As a result, highly nontrivial kinetic-mixings appear among the spherical Kaluza-Klein modes of the $(1+1)\mathrm{d}$ near-horizon reduced theory, which obscures the traditional derivation of the Hawking flux. However, after a series of field redefinitions, we can disentangle the mode-mixings into canonical normal modes, but the reduced metrics for these normal modes are mode-dependent. Despite of this, the resultant Hawking flux turns out to be mode-independent and remains the same as the Schwarzschild’s one. Thus, one cannot tell the black holes with nonlinear supertranslation hairs from the Schwarzschild’s one by examining the Hawking flux, so that the nonlinear soft hairs can be thought as the microstates.

Quantitative studies of the evolution and cosmological consequences of networks of cosmic strings (or other topological defects) require a combination of numerical simulations and analytic modeling with the velocity-dependent one-scale (VOS) model. In previous work, we demonstrated that a GPU-accelerated code for local Abelian-Higgs string networks enables a statistical separation of key dynamical processes affecting the evolution of the string networks and thus a precise calibration of the VOS model. Here we further exploit this code in a detailed study of two important aspects connecting the simulations with the VOS model. First, we study the sensitivity of the model calibration to the presence (or absence) of thermal oscillations due to high gradients in the initial conditions. This is relevant since in some Abelian-Higgs simulations described in the literature a period of artificial (unphysical) dissipation—usually known as cooling—is introduced with the goal of suppressing these oscillations and accelerating the convergence to scaling. We show that a small amount of cooling has no statistically significant impact on the VOS model calibration, while a longer dissipation period does have a noticeable effect. Second, in doing this analysis we also introduce an improved Markov Chain Monte Carlo based pipeline for calibrating the VOS model, Comparison to our previous bootstrap based pipeline shows that the latter accurately determined the best-fit values of the VOS model parameter, but underestimated the uncertainties in some of the parameters. Overall, our analysis shows that the calibration pipeline is robust and can be applied to future much larger field theory simulations.

We present results from the FUNK experiment in the search for hidden-photon dark matter. Near the surface of a mirror, hidden photons may be converted into ordinary photons. These photons are emitted perpendicularly to the surface and have an energy equal to the mass of the dark matter hidden photon. Our experimental setup consists of a large, spherical mirror with an area of more than $14{\mathrm{m}}^2$, which concentrates the emitted photons into its central point. Using a detector sensitive to visible and near-UV photons, we can exclude a kinetic-mixing coupling of stronger than $\chi \approx {10}^{-12}$ in the mass range of 2.5 to 7 eV, assuming hidden photons comprise all of the dark matter. The experimental setup and analysis used to obtain this limit are discussed in detail.

We demonstrate the scale invariance of the vacuum Bianchi type IX equations and use this to argue for the possibility of multifractal turbulence as a realization of the suggestion by Belinski that there will be a fragmentation of local regions of inhomogeneous Mixmaster chaos on approach to an initial inhomogeneous cosmological singularity. Differences between the gravitational and hydrodynamical situations are outlined. Various potential obstacles to this picture of gravitational turbulence are discussed together with links to preinflation.

In the low-energy effective theory of neutrinos, the Haar measure for unitary matrices is very likely to give rise to something similar to the observed Pontecorvo-Maki-Nakagawa-Sakata matrix. Assuming the Haar measure, we determine the probability density functions for all quadratic, quartic Majorana, and quartic Dirac rephasing invariants for an arbitrary number of neutrino generations. We show that for a fixed number of neutrinos, all rephasing invariants of the same type have the same probability density function under the Haar measure. We then compute the moments of the rephasing invariants to determine, with the help of the Mellin transform, the three probability density functions. We finally investigate the physical implications of our results in function of the number of neutrinos.

The Standard Model (SM), when extended with a leptoquark (LQ) and right-handed neutrinos, can have interesting new implications for Higgs physics. We show that sterile neutrinos can induce a boost to the down-type quark Yukawa interactions through a diagonal coupling associated with the quarks and a scalar LQ of electromagnetic charge $1/3$. The relative change is moderately larger in the case of the first two generations of quarks, as they have vanishingly small Yukawa couplings in the SM. The enhancement in the couplings would also lead to a non-negligible contribution from the quark fusion process to the production of the 125 GeV Higgs scalar in the SM, though the gluon fusion always dominates. However, this may not be true for a general scalar. As an example, we consider a scenario with a SM-gauge-singlet scalar $\varphi$ where an $\mathcal{O}(1)$ coupling between $\varphi$ and the LQ is allowed. The $\varphi q\overline{q}$ Yukawa couplings can be generated radiatively only through a loop of LQ and sterile neutrinos. Here, the quark fusion process can have a significant cross section, especially for a light $\varphi$. It can even supersede the normally dominant gluon fusion process for a moderate to large value of the LQ mass. This model can be tested/constrained at the high luminosity run of the LHC through a potentially large branching fraction of the scalar to two jets.

Experiments searching for the electric dipole moment (EDM) of the electron $d_e$ utilize atomic/molecular states with one or more uncompensated electron spins, and these paramagnetic systems have recently achieved remarkable sensitivity to $d_e$. If the source of $CP$ violation resides entirely in the hadronic sector, the two-photon exchange processes between electrons and the nucleus induce $CP$-odd semileptonic interactions, parametrized by the Wilson coefficient $C_{\mathrm{SP}}$, and provide the dominant source of EDMs in paramagnetic systems instead of $d_e$. We evaluate the $C_{\mathrm{SP}}$ coefficients induced by the leading hadronic sources of $CP$ violation, namely, nucleon EDMs and $CP$-odd pion-nucleon couplings, by calculating the nucleon-number-enhanced $CP$-odd nuclear scalar polarizability, employing chiral perturbation theory at the nucleon level and the Fermi-gas model for the nucleus. This allows us to translate the ACME EDM limits from paramagnetic ThO into novel-independent constraints on the QCD theta term $|\overline{\theta }|<3\times {10}^{-8}$, proton EDM $|d_p|<2\times {10}^{-23}e\mathrm{cm}$, isoscalar $CP$-odd pion-nucleon coupling $|{\overline{g}}_{\pi NN}^{(1)}|<4\times {10}^{-10}$, and color EDMs of quarks $|{\tilde{d}}_u-{\tilde{d}}_d|<2\times {10}^{-24}\mathrm{cm}$. We note that further experimental progress with EDM experiments in paramagnetic systems may allow them to rival the sensitivity of EDM experiments with neutrons and diamagnetic atoms to these quantities.

We propose a new version of the $\mathrm{AdS}/\mathrm{CFT}$ correspondence, where polymer structures similar to loop quantum cosmology spin networks can be induced on an isotropic and homogeneous flat Randall-Sundrum II brane, corresponding to the holographic duals of closed string states living in the bulk. Such polymer structures drive a discrete evolution of the braneworld spacetime that leads to the regularization of the big bang singularity. The present results show that the $\mathrm{AdS}/\mathrm{CFT}$ conjecture can be a possible bridge between string theory and loop quantum gravity.