Acceleration of $\pi$’s and $\mu$’s modifies the flavor ratio at Earth (at astrophysical sources) of neutrinos produced by $\pi$ decay, ${\nu }_e:{\nu }_{\mu }:{\nu }_{\tau }$, from $1:1:1$ ($1:2:0$) to $1:1.8:1.8$ ($0:1:0$) at high energy, because $\pi$’s decay more than $\mu$’s during secondary acceleration. The neutrino spectrum accompanies a flat excess, differently from the case of energy losses. With the flavor spectra, we can probe time scales of cosmic-ray acceleration and shock dynamics. We obtain general solutions of convection-diffusion equations and apply them to gamma-ray bursts, which may have the flavor modification at around PeV–EeV detectable by IceCube and next-generation experiments.

We describe the quantum flat universe in Quantum Reduced Loop Gravity in terms of states based on cuboidal graphs with six-valent nodes. We investigate the action of the scalar constraint operator at each node, and we construct proper semiclassical states. This allows us to discuss the semiclassical effective dynamics of the quantum universe, which resembles that of Loop Quantum Cosmology. In particular, the regulator is identified with the third root of the inverse number of nodes within each homogeneous patch, while inverse-volume corrections are enhanced.

We examine the spatial extrema (local maxima, minima and saddle points) of the covariant scalars (density, Hubble expansion, spatial curvature and eigenvalues of the shear and electric Weyl tensors) of the quasispherical Szekeres dust models. Sufficient conditions are obtained for the existence of distributions of multiple extrema in spatial comoving locations that can be prescribed through initial conditions. These distributions evolve without shell crossing singularities at least for ever expanding models (with or without cosmological constant) in the full evolution range where the models are valid. By considering the local maxima and minima of the density, our results allow for setting up elaborated networks of “pancake” shaped evolving cold dark matter overdensities and density voids whose spatial distribution and amplitudes can be controlled from initial data compatible with standard early Universe initial conditions. We believe that these results have an enormous range of potential application by providing a fully relativistic nonperturbative coarse grained modeling of cosmic structure at all scales.

Redshift-space distortions in galaxy surveys happen along the radial direction, breaking statistical translation invariance. We construct estimators for radial distortions that, using only fast fourier transforms (FFTs) of the overdensity field multipoles for a given survey geometry, compute the power spectrum monopole, quadrupole and hexadecapole, and generalize such estimators to the bispectrum. Using realistic mock catalogs we compare the signal to noise of two estimators for the power spectrum hexadecapole that require different number of FFTs and measure the bispectrum monopole, quadrupole and hexadecapole. The resulting algorithm is very efficient, e.g. the BOSS survey requires about 3 min for $\ell =0,2,4$ power spectra for scales up to $k=0.3h{\mathrm{Mpc}}^{-1}$ and about 15 additional min for $\ell =0,2,4$ bispectra for all scales and triangle shapes up to $k=0.2h{\mathrm{Mpc}}^{-1}$ on a single core. The speed of these estimators is essential as it makes possible for one to compute covariance matrices from large number of realizations of mock catalogs with realistic survey characteristics, and paves the way for improved constraints of gravity on cosmological scales, inflation and galaxy bias.

We derive the second-order hydrodynamic equation and the microscopic formulas of the relaxation times as well as the transport coefficients systematically from the relativistic Boltzmann equation. Our derivation is based on a novel development of the renormalization-group method, a powerful reduction theory of dynamical systems, which has been applied successfully to derive the nonrelativistic second-order hydrodynamic equation. Our theory nicely gives a compact expression of the deviation of the distribution function in terms of the linearized collision operator, which is different from those used as an ansatz in the conventional fourteen-moment method. It is confirmed that the resultant microscopic expressions of the transport coefficients coincide with those derived in the Chapman-Enskog expansion method. Furthermore, we show that the microscopic expressions of the relaxation times have natural and physically plausible forms. We prove that the propagating velocities of the fluctuations of the hydrodynamical variables do not exceed the light velocity, and hence our second-order equation ensures the desired causality. It is also confirmed that the equilibrium state is stable for any perturbation described by our equation.

We investigate a class of relativistic fermion theories in $2<d<4$ space-time dimensions with continuous chiral $\mathrm{U}(N_{\mathrm{f}})\times \mathrm{U}(N_{\mathrm{f}})$ symmetry. This includes a number of well-studied models, e.g., of Gross-Neveu and Thirring type, in a unified framework. Within the limit of pointlike interactions, the RG flow of couplings reveals a network of interacting fixed points, each of which defines a universality class. A subset of fixed points are “critical fixed points” with one RG relevant direction being candidates for critical points of second-order phase transitions. Identifying invariant hyperplanes of the RG flow and classifying their attractive/repulsive properties, we find evidence for emergent higher chiral symmetries as a function of $N_{\mathrm{f}}$. For the case of the Thirring model, we discover a new critical flavor number that separates the RG stable large-$N_{\mathrm{f}}$ regime from an intermediate-$N_{\mathrm{f}}$ regime in which symmetry-breaking perturbations become RG relevant. This new critical flavor number has to be distinguished from the chiral-critical flavor number, below which the Thirring model is expected to allow spontaneous chiral symmetry breaking, and its existence offers a resolution to the discrepancy between previous results obtained in the continuum and the lattice Thirring models. Moreover, we find indications for a new feature of universality: details of the critical behavior can depend on additional “spectator symmetries” that remain intact across the phase transition. Implications for the physics of interacting fermions on the honeycomb lattice, for which our theory space provides a simple model, are given.

We derive a formula for the entanglement entropy of squeezed states on a lattice in terms of the complex structure $J$. The analysis involves the identification of squeezed states with group-theoretical coherent states of the symplectic group and the relation between the coset $Sp(2N,\mathbb{R})/\text{Isot}(J_0)$ and the space of complex structures. We present two applications of the new formula: (i) we derive the area law for the ground state of a scalar field on a generic lattice in the limit of small speed of sound, (ii) we compute the rate of growth of the entanglement entropy in the presence of an instability and show that it is asymptotically bounded from above by the Kolmogorov-Sinai rate.

The proof of the multi-Regge form of multiple production amplitudes in the next-to-leading logarithmic approximation is presented for Yang-Mills theories with fermions and scalars in any representations of the color group and with any Yukawa-type interaction. Explicit expressions for the Reggeized gauge boson trajectory, the Reggeon vertices, and the impact factors are given. Fulfillment of the bootstrap conditions is proved.

We have studied the dynamics of an equal-mass magnetized neutron-star binary within a resistive magnetohydrodynamic (RMHD) approach in which the highly conducting stellar interior is matched to an electrovacuum exterior. Because our analysis is aimed at assessing the modifications introduced by resistive effects on the dynamics of the binary after the merger and through to collapse, we have carried out a close comparison with an equivalent simulation performed within the traditional ideal magnetohydrodynamic approximation. We have found that there are many similarities between the two evolutions but also one important difference: the survival time of the hypermassive neutron star increases in a RMHD simulation. This difference is due to a less efficient magnetic-braking mechanism in the resistive regime, in which matter can move across magnetic-field lines, thus reducing the outward transport of angular momentum. Both the RMHD and the ideal magnetohydrodynamic simulations carried here have been performed at higher resolutions and with a different grid structure than those in previous work of ours [L. Rezzolla, B. Giacomazzo, L. Baiotti, J. Granot, C. Kouveliotou, and M. A. Aloy, Astrophys. J. Letters 732, L6 (2011)] but confirm the formation of a low-density funnel with an ordered magnetic field produced by the black hole-torus system. In both regimes the magnetic field is predominantly toroidal in the highly conducting torus and predominantly poloidal in the nearly evacuated funnel. Reconnection processes or neutrino annihilation occurring in the funnel, none of which we model, could potentially increase the internal energy in the funnel and launch a relativistic outflow, which, however, is not produced in these simulations.

Computations of quantum corrections to the cosmic microwave background spectrum and to scalar field dynamics during inflation very often take advantage of the “semiclassical” approach, where the metric fluctuations are simply omitted. On the other hand, a complete computation ought to take into account that the matter field perturbation and scalar metric perturbation together constitute a single physical degree of freedom. The question then naturally arises, in which sense the semiclassical approach is an approximation to the complete calculation, and whether there are specific limits where this is also a good approximation. We demonstrate this by explicitly computing the leading quantum radiative corrections to the evolution equation of the mean field (“condensate”) and the Friedmann equations taking into account scalar perturbations of both the matter field and the metric, and when omitting the latter. We find that the two agree in the limit $H\ll M_{\text{pl}}$, but one is not a limit of the other. We also find that in simple models of inflation, $H/M_{\text{pl}}$ is not small enough that the two approaches can be said to agree.

We study the weak decay of the ${\mathrm{\Lambda }}_b$ into $J/\psi K\mathrm{\Xi }$ and $J/\psi \eta \mathrm{\Lambda }$ states, and relate these processes to the ${\mathrm{\Lambda }}_b\to J/\psi \overline{K}N$ decay mode. The elementary weak transition at the quark level proceeds via the creation of a $J/\psi$ meson and an excited $sud$ system with $I=0$, which upon hadronization leads to $\overline{K}N$ or $\eta \mathrm{\Lambda }$ pairs. These states undergo final-state interaction in coupled channels and produce a final meson-baryon pair. The $K\mathrm{\Xi }$ state only occurs via rescattering, hence making the ${\mathrm{\Lambda }}_b\to J/\psi K\mathrm{\Xi }$ process very sensitive to the details of the meson-baryon interaction in strangeness $S=-1$ and isospin $I=0$. We show that the corresponding invariant mass distribution is dominated by the next-to-leading-order terms of the chiral interaction. The $I=0$ selectivity of this decay, and its large sensitivity to the higher-order terms, makes its measurement very useful and complementary to the $K^{-}p\to K\mathrm{\Xi }$ cross section data. The rates of the ${\mathrm{\Lambda }}_b\to J/\psi K\mathrm{\Xi }$ and ${\mathrm{\Lambda }}_b\to J/\psi \eta \mathrm{\Lambda }$ invariant mass distributions are sizable compared to those of the ${\mathrm{\Lambda }}_b\to J/\psi \overline{K}N$ decay, which is measured experimentally, and thus, we provide arguments for an experimental determination of these decay modes that will help us understand better the chiral dynamics at higher energies.

We propose a new mechanism for baryogenesis at the 1–200 MeV scale. Enhancement of charge parity ($CP$) violation takes place via interference between oscillations and decays of mesinos—bound states of a scalar quark and antiquark and their $CP$ conjugates. We present the mechanism in a simplified model with four new fundamental particles, with masses between 300 GeV and 10 TeV, and show that some of the experimentally allowed parameter space can give the observed baryon-to-entropy ratio.

An important ingredient of many composite Higgs scenarios is partial compositeness: a mass for the top quark is generated via mixing with baryonic operators of the same new strong dynamics that produces the composite Higgs particle. These baryonic operators are scale dependent. We construct these operators, and calculate their one-loop anomalous dimension, in a set of ultraviolet completions of the standard model proposed by Ferretti and Karateev.

Measurements of the off-shell Higgs boson production cross section in $gg(\to h^{*})\to ZZ$ have recently been used by the CMS and ATLAS collaborations to indirectly constrain the total width of the Higgs boson. I point out that the interpretation of these measurements as a Higgs width constraint can be invalidated if additional neutral Higgs boson(s) are present with masses below about 350 GeV.

We examine the deflected mirage mediation supersymmetry breaking (DMMSB) scenario, which combines three supersymmetry breaking scenarios, namely anomaly mediation, gravity mediation and gauge mediation using the one-loop renormalization group invariants (RGIs). We examine the effects on the RGIs at the threshold where the gauge messengers emerge, and derive the supersymmetry breaking parameters in terms of the RGIs. We further discuss whether the supersymmetry breaking mediation mechanism can be determined using a limited set of invariants, and derive sum rules valid for DMMSB below the gauge messenger scale. In addition we examine the implications of the measured Higgs mass for the DMMSB spectrum.

We investigate the phenomenological viability of a recently proposed class of composite dark matter models where the relic density is determined by $3\to 2$ number-changing processes in the dark sector. Here the pions of the strongly interacting field theory constitute the dark matter particles. By performing a consistent next-to-leading- and next-to-next-to-leading-order chiral perturbative investigation we demonstrate that the leading-order analysis cannot be used to draw conclusions about the viability of the model. We further show that higher-order corrections substantially increase the tension with phenomenological constraints challenging the viability of the simplest realization of the strongly interacting massive particle paradigm.

Positive parity meson states $D_{s0}^{*}(2317{)}^{+}$ and $D_{s1}(2460{)}^{+}$ have masses slightly below the $DK$ threshold. Both states can strongly decay only into isospin violating decays $D_{s1}(2460{)}^{+}\to D_s^{+}\pi \pi$, $D_{s1}(2460{)}^{+}\to D_s^{*+}{\pi }^0$, and $D_{s0}^{*}(2317{)}^{+}\to D_s^{+}{\pi }^0$. The $\pi$ states have rather small energies, which makes these decays appropriate to study within heavy meson chiral perturbation theory and to calculate loop contributions. The $D_{s1}(2460{)}^{+}\to D_s^{+}\pi \pi$ decays occur only at the loop level. Amplitude is a result of chiral loop contributions, which then have to be finite. However, in the case of $D_{s1}(2460{)}^{+}\to D_s^{*+}{\pi }^0$ and $D_{s0}^{*}(2317{)}^{+}\to D_s^{+}{\pi }^0$ decays, there is a tree-level contribution. We find that chiral loop contributions might be important in both cases. The calculated amplitudes are sensitive on the coupling constant describing the interaction of positive and negative parity heavy meson multiplets with the light pseudoscalars. The counterterm contributions are also present in the amplitudes $D_{s1}(2460{)}^{+}\to D_s^{*+}{\pi }^0$ and $D_{s0}^{*}(2317{)}^{+}\to D_s^{+}{\pi }^0$. We explore an experimentally known ratio of the decay widths for these two decay modes to estimate the size of counterterm contributions. We determine decay widths for both decay modes to be $\mathrm{\Gamma }(D_{s1}(2460{)}^{+}\to D_s^{+}{\pi }^{+}{\pi }^{-})\simeq 0.25\mathrm{keV}$ and $\mathrm{\Gamma }(D_{s1}(2460{)}^{+}\to D_s^{+}{\pi }^0{\pi }^0)\simeq 0.15\mathrm{keV}$.

Using the repeated Laplace transform, we find an analytical solution for Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations for extracting the pion, kaon, and proton fragmentation functions at next-to-leading-order approximation. We also study the symmetry breaking of the sea quarks fragmentation functions $D_{\overline{q}}^h(z,Q^2)$ and simply separate them according to their mass ratio. Finally, we calculate the total fragmentation functions of these hadrons and compare them with experimental data and those from global fits. Our results show a good agreement with the fragmentation functions obtained from global parametrizations as well as with the experimental data.

The numerically dominant QED contributions to the anomalous magnetic moment of the muon stem from Feynman diagrams with internal electron loops. We consider such corrections and present a calculation of the four-loop light-by-light-type corrections where the external photon couples to a closed electron or muon loop. We perform an asymptotic expansion in the ratio of electron and muon mass and reduce the resulting integrals to master integrals which we evaluate using analytical and numerical methods. We confirm the results present in the literature which are based on different computational methods.