We study a testable dark-matter (DM) model outside of the standard weakly interacting massive particle paradigm in which the observed ratio ${\mathrm{\Omega }}_{\mathrm{dark}}\simeq {\mathrm{\Omega }}_{\text{visible}}$ for visible and dark-matter densities finds its natural explanation as a result of their common QCD origin when both types of matter (DM and visible) are formed at the QCD phase transition and both are proportional to ${\mathrm{\Lambda }}_{\mathrm{QCD}}$. Instead of the conventional “baryogenesis” mechanism, we advocate a paradigm when the “baryogenesis” is actually a charge separation process which always occurs in the presence of the $CP$ odd axion field $a(x)$. In this scenario, the global baryon number of the Universe remains zero, while the unobserved antibaryon charge is hidden in the form of heavy nuggets, similar to Witten’s strangelets and compromise the DM of the Universe. In the present work, we study in great detail a possible formation mechanism of such macroscopically large heavy objects. We argue that the nuggets will be inevitably produced during the QCD phase transition as a result of Kibble-Zurek mechanism on formation of the topological defects during a phase transition. Relevant topological defects in our scenario are the closed bubbles made of the $N_{\mathrm{DW}}=1$ axion domain walls. These bubbles, in general, accrete the baryon (or antibaryon) charge, which eventually results in the formation of the nuggets and antinuggets carrying a huge baryon (antibaryon) charge. A typical size and the baryon charge of these macroscopically large objects are mainly determined by the axion mass $m_a$. However, the main consequence of the model, ${\mathrm{\Omega }}_{\mathrm{dark}}\approx {\mathrm{\Omega }}_{\text{visible}}$, is insensitive to the axion mass which may assume any value within the observationally allowed window ${10}^{-6}\mathrm{eV}\lesssim m_a\lesssim {10}^{-3}\mathrm{eV}$. We also estimate the baryon-to-entropy ratio $\eta \equiv n_B/n_{\gamma }\sim {10}^{-10}$ within this scenario. Finally, we comment on implications of these results to the axion search experiments, including the microwave cavity and the Orpheus experiments.

One of the outstanding problems in general relativistic cosmology is that of the averaging, that is, how the lumpy universe that we observe at small scales averages out to a smooth Friedmann-Lemaître-Robertson-Walker (FLRW) model. The root of the problem is that averaging does not commute with the Einstein equations that govern the dynamics of the model. This leads to the well-known question of backreaction in cosmology. In this work, we approach the problem using the covariant framework of macroscopic gravity. We use its cosmological solution with a flat FLRW macroscopic background where the result of averaging cosmic inhomogeneities has been encapsulated into a backreaction density parameter denoted ${\mathrm{\Omega }}_{\mathcal{A}}$. We constrain this averaged universe using available cosmological data sets of expansion and growth including, for the first time, a full cosmic microwave background analysis from Planck temperature anisotropy and polarization data, the supernova data from Union 2.1, the galaxy power spectrum from WiggleZ, the weak lensing tomography shear-shear cross correlations from the CFHTLenS survey, and the baryonic acoustic oscillation data from 6Df, SDSS DR7, and BOSS DR9. We find that $-0.0155\le {\mathrm{\Omega }}_{\mathcal{A}}\le 0$ (at the 68% C.L.), thus providing a tight upper bound on the backreaction term. We also find that the term is strongly correlated with cosmological parameters, such ${\mathrm{\Omega }}_{\mathrm{\Lambda }}$, ${\sigma }_8$, and $H_0$. While small, a backreaction density parameter of a few percent should be kept in consideration along with other systematics for precision cosmology.

In a Rindler-type coordinate system spanned in a region outside of a black hole horizon, we have nonvanishing classical holographic charges as soft hairs on the horizon for stationary black holes. Taking a large black hole mass limit, the spacetimes with the charges are described by asymptotic Rindler metrics. We construct a general theory of gravitational holographic charges for a ($1+3$)-dimensional linearized gravity field in the Minkowski background with Rindler horizons. Although matter crossing a Rindler horizon causes horizon deformation and a time-dependent coordinate shift—that is, gravitational memory—the supertranslation and superrotation charges on the horizon can be defined during and after its passage through the horizon. It is generally proven that holographic states on the horizon cannot store any information about absorbed perturbative gravitational waves. However, matter crossing the horizon really excites holographic states. By using gravitational memory operators, which consist of the holographic charge operators, we suggest a resolution of the no-cloning paradox of quantum information between matter falling into the horizon and holographic charges on the horizon from the viewpoint of the contextuality of quantum measurement.

Nonvirialized dark-matter axions may be present in the Milky Way halo in the form of low-velocity-dispersion flows. The Axion Dark-Matter eXperiment performed a search for the conversion of these axions into microwave photons using a resonant cavity immersed in a strong, static magnetic field. The spread of photon energy in these measurements was measured at spectral resolutions of the order of 1 Hz and below. If the energy variation were this small, the frequency modulation of any real axion signal due to the orbital and rotational motion of Earth would become non-negligible. Conservative estimates of the expected signal modulation were made and used as a guide for the search procedure. The photon frequencies covered by this search are 812–852 and 858–892 MHz, which correspond to an axion mass of 3.36–3.52 and $3.55–3.69\mu \mathrm{eV}$. No axion signal was found, and limits were placed on the maximum local density of nonvirialized axions of these masses.

The Higgs boson discovered at the LHC opened a new chapter for particle physics. Its properties need to be studied in detail to distinguish a purely standard model (SM) Higgs boson from one of many scalars in an enlarged Higgs sector. The CMS Collaboration has reported a possible signal for lepton flavor violation in $h\to \mu \tau$, which if confirmed, implies that the Higgs sector is larger than in the SM. New physics responsible for this type of decay may, in general, also introduce other observable effects such as charge-parity ($CP$) violation in $h\to \tau \tau$. We study two types of models that single out the third generation and can induce large $h\to \mu \tau$ rates with different consequences for $CP$ violation in $h\to \tau \tau$. Predictions for the size of the $CP$ violating couplings require knowledge of the lepton Yukawa matrices and we discuss this in the context of two different textures considering all existing constraints.

The explicit breaking of chiral symmetry of the Wilson fermion action results in additive quark mass renormalization. Moreover, flavor singlet and nonsinglet scalar currents acquire different renormalization constants with respect to continuum regularization schemes. This complicates keeping the renormalized strange quark mass fixed when varying the light quark mass in simulations with $N_f=2+1$ sea quark flavors. Here we present and validate our strategy within the CLS (coordinated lattice simulations) effort to achieve this in simulations with nonperturbatively order-$a$ improved Wilson fermions. We also determine various combinations of renormalization constants and improvement coefficients.

In the era of precision physics measurements at the LHC, efficient and exhaustive estimations of theoretical uncertainties play an increasingly crucial role. In the context of Monte Carlo (MC) event generators, the estimation of such uncertainties traditionally requires independent MC runs for each variation, for a linear increase in total run time. In this work, we report on an automated evaluation of the dominant (renormalization-scale and nonsingular) perturbative uncertainties in the pythia 8 event generator, with only a modest computational overhead. Each generated event is accompanied by a vector of alternative weights (one for each uncertainty variation), with each set separately preserving the total cross section. Explicit scale-compensating terms can be included, reflecting known coefficients of higher-order splitting terms and reducing the effect of the variations. The formalism also allows for the enhancement of rare partonic splittings, such as $g\to b\overline{b}$ and $q\to q\gamma$, to obtain weighted samples enriched in these splittings while preserving the correct physical Sudakov factors.

We revisit the $\rho$-meson longitudinal leading-twist distribution amplitude (DA) ${\varphi }_{2;\rho }^{\parallel }$ by using the QCD sum rules approach within the background field theory. To improve the accuracy of the sum rules for its moments $⟨{\xi }_{n;\rho }^{\parallel }⟩$, we include the next-to-leading order QCD correction to the perturbative part and keep all nonperturbative condensates up to dimension-six consistently within the background field theory. The first two moments read $⟨{\xi }_{2;\rho }^{\parallel }⟩{|}_{1\mathrm{GeV}}=0.241(28)$ and $⟨{\xi }_{4;\rho }^{\parallel }⟩{|}_{1\mathrm{GeV}}=0.109(10)$, indicating a double humped behavior for ${\varphi }_{2;\rho }^{\parallel }$ at small energy scale. As an application, we apply them to the $B\to \rho$ transition form factors within the QCD light-cone sum rules, which are key components for the decay width $\mathrm{\Gamma }(B\to \rho \ell {\nu }_{\ell })$. To compare with the world average of $\mathrm{\Gamma }(B\to \rho \ell {\nu }_{\ell })$ issued by Particle Data Group, we predict $|V_{\mathrm{ub}}|=3.19_{-0.62}^{+0.65}$, which agrees with the BABAR and Omnès parametrization prediction within errors.

This paper provides results for the ground state and excited spectra of three-flavored doubly heavy baryons, $bcn$ and $bcs$. We take advantage of the spin-independent interaction recently obtained to reconcile the lattice SU(3) QCD static potential and the results of nonperturbative lattice QCD for the triply heavy baryon spectra. We show that the spin-dependent potential might be constrained on the basis of nonperturbative lattice QCD results for the spin splittings of three-flavored doubly heavy baryons. Our results may also represent a challenge for future lattice QCD work, because a smaller lattice error could help in distinguishing between different prescriptions for the spin-dependent part of the interaction. Thus, by comparing with the reported baryon spectra obtained with parameters estimated from lattice QCD, one can challenge the precision of lattice calculations. The present work supports a coherent description of singly, doubly and triply heavy baryons with the same Cornell-like interacting potential. The possible experimental measurement of these states at LHCb is an incentive for this study.

We study the splitting in the screening mass of pions and the $\eta$-meson across the chiral crossover. This splitting is determined by the ’t Hooft determinant. We use results for the renormalization group scale dependence of the ’t Hooft determinant obtained within the functional renormalization group in quenched QCD with two flavors. The scale dependence of the ’t Hooft determinant is mapped to its temperature dependence with the help of a Polyakov-quark-meson model. As a result we obtain the temperature dependence of the splitting in the screening mass of pions and the $\eta$-meson.

We provide an updated analysis of the forward $J/\psi$-p scattering amplitude, relating its imaginary part to $\gamma p\to J/\psi p$ and $\gamma p\to c\overline{c}X$ cross section data, and calculating its real part through a once-subtracted dispersion relation. From a global fit to both differential and total cross section data, we extract a value for the spin-averaged $J/\psi$-p s-wave scattering length $a_{\psi p}=0.046\pm 0.005\mathrm{fm}$, which can be translated into a $J/\psi$ binding energy in nuclear matter of $B_{\psi }=2.7\pm 0.3\mathrm{MeV}$. We estimate the forward-backward asymmetry to the $\gamma p\to e^{-}{e}^{+}p$ process around the $J/\psi$ resonance, which results from interchanging the leptons in the interference between the $J/\psi$ production and the Bethe-Heitler mechanisms. We show that to good approximation this asymmetry depends linearly on $a_{\psi p}$, and can reach values around $-25\%$ for forthcoming $J/\psi$ threshold production experiments at Jefferson Lab. Its measurement can thus provide a very sensitive observable for a refined extraction of $a_{\psi p}$.

As an extension to our previous work, we study the transport properties of the Witten-Sakai-Sugimoto model in the black D4-brane background with smeared D0 branes (D0-D4/D8 system). Because of the presence of the D0 branes, in the bubble configuration, this model is holographically dual to four-dimensional QCD or Yang-Mills theory with a Chern-Simons term, and the number density of the D0 branes corresponds to the coupling constant ($\theta$ angle) of the Chern-Simons term in the dual field theory. In this paper, we accordingly focus on the small number density of the D0 branes to study the sound mode in the black D0-D4 brane system since the coupling of the Chern-Simons term should be quite weak in QCD. Then, we derive its five-dimensional effective theory and analytically compute the speed of sound and the sound wave attenuation in the approach of gauge/gravity duality. Our result shows the speed of sound and the sound wave attenuation are modified by the presence of the D0 branes. Thus, they depend on the $\theta$ angle or chiral potential in this holographic description.

We construct a new class of superstrata, the regular supergravity solutions describing the microstates of D1-D5-P black holes. Our solutions are obtained by adding momentum charge to the D1-D5 geometries based on multiple concentric Kaluza-Klein monopoles.

We investigate the stability of the pion string in a thermal bath and a dense medium. We find that stability is dependent on the order of the chiral transition. String core stability within the experimentally allowed regime is found only if the chiral transition is second order, and even there the stable region is small; i.e., the temperature below which the core is unstable is close to the critical temperature of the phase transition. We also find that the presence of a dense medium, in addition to the thermal bath, enhances the experimentally accessible region with stable strings. We also argue that once the string core decays, the “effective winding” of the string persists at large distances from the string core. Our analysis is done both in the chiral limit, which is mainly what has been explored in the literature up to now, and for the physical $h\ne 0$ case, where a conceptual framework is set up for addressing this regime and some simple estimates are done.

Using novel nonlinear kinetic terms for gravitons, a large class of bigravity models was constructed, which are potentially free of the Boulware-Deser (BD) ghost, at the price of the presence of spin-2 ghosts. In this work, we derive their Hamiltonians using the Arnowitt-Deser-Misner formalism, and verify that the BD ghost is eliminated by additional constraints. The general Hamiltonian structure is analogous to that of the other class of bigravity models free of the BD ghost.

A set of novel derivative terms for spin-2 fields are proposed. They are the wedge products of curvature two-forms and vielbeins. In this work, we investigate the properties of novel two-derivative terms in the context of bigravity. Based on a minisuperspace analysis, we identify a large class of bigravity models where the Boulware-Deser ghost could be absent. We give a new perspective that Weyl gravity and new massive gravity belong to this class of bigravity models involving novel derivative terms. This is related to the fact that this class of models contains spin-2 ghosts. In addition, we discuss the UV cutoff scales, dynamical symmetric conditions, and novel higher-derivative terms.

We analyze from a classical and quantum point of view the behavior of the Universe close to a little rip, which can be interpreted as a big rip sent towards the infinite future. Like a big rip singularity, a little rip implies the destruction of all bounded structures in the Universe and is thus an event where quantum effects could be important. We present here a new phantom scalar field model for the little rip. The quantum analysis is performed in quantum geometrodynamics, with the Wheeler-DeWitt equation as its central equation. We find that the little rip can be avoided in the sense of the DeWitt criterion, that is, by having a vanishing wave function at the place of the little rip. Therefore our analysis completes the answer to the question: can quantum cosmology smoothen or avoid the divergent behavior genuinely caused by phantom matter? We show that this can indeed happen for the little rip, similar to the avoidance of a big rip and a little sibling of the big rip.

We consider decaying dark matter with masses $10^7\lesssim M\lesssim 10^{16}\mathrm{GeV}$ as a source of ultrahigh energy (UHE) gamma rays. Using recent limits on UHE gamma-ray flux for energies $E_{\gamma }>2\times 10^{14}\mathrm{eV}$, provided by extensive air shower observatories, we put limits on masses and lifetimes of the dark matter. We also discuss possible dark matter decay origin of tentative 100 PeV photon flux detected with the EAS-MSU experiment.

Weak gravitational lensing is becoming a mature technique for constraining cosmological parameters, and future surveys will be able to constrain the dark energy equation of state $w$. When analyzing galaxy surveys, redshift information has proven to be a valuable addition to angular shear correlations. We forecast parameter constraints on the triplet $({\mathrm{\Omega }}_m,w,{\sigma }_8)$ for a LSST-like photometric galaxy survey, using tomography of the shear-shear power spectrum, convergence peak counts and higher convergence moments. We find that redshift tomography with the power spectrum reduces the area of the $1\sigma$ confidence interval in $({\mathrm{\Omega }}_m,w)$ space by a factor of 8 with respect to the case of the single highest redshift bin. We also find that adding non-Gaussian information from the peak counts and higher-order moments of the convergence field and its spatial derivatives further reduces the constrained area in $({\mathrm{\Omega }}_m,w)$ by factors of 3 and 4, respectively. When we add cosmic microwave background parameter priors from Planck to our analysis, tomography improves power spectrum constraints by a factor of 3. Adding moments yields an improvement by an additional factor of 2, and adding both moments and peaks improves by almost a factor of 3 over power spectrum tomography alone. We evaluate the effect of uncorrected systematic photometric redshift errors on the parameter constraints. We find that different statistics lead to different bias directions in parameter space, suggesting the possibility of eliminating this bias via self-calibration.