The reduced cross sections for $e^{+}p$ deep inelastic scattering have been measured with the ZEUS detector at HERA at three different center-of-mass energies, 318, 251 and 225 GeV. The cross sections, measured double differentially in Bjorken $x$ and the virtuality, $Q^2$, were obtained in the region $0.13\le y\le 0.75$, where $y$ denotes the inelasticity and $5\le Q^2\le 110{\mathrm{GeV}}^2$. The proton structure functions $F_2$ and $F_L$ were extracted from the measured cross sections.

We present measurements of the forward-backward asymmetry in the angular distribution of leptons from decays of top quarks and antiquarks produced in proton-antiproton collisions. We consider the final state containing a lepton and at least three jets. The entire sample of data collected by the D0 experiment during Run II of the Fermilab Tevatron Collider, corresponding to $9.7{\mathrm{fb}}^{-1}$ of integrated luminosity, is used. The asymmetry measured for reconstructed leptons is $A_{\mathrm{FB}}^l=(2.9\pm 2.1{(\text{stat}.)}_{-1.7}^{+1.5}(\text{syst}.))\%$. When corrected for efficiency and resolution effects within the lepton rapidity coverage of $|y_l|<1.5$, the asymmetry is found to be $A_{\mathrm{FB}}^l=(4.2\pm 2.3{(\text{stat}.)}_{-2.0}^{+1.7}(\text{syst}.))\%$. We examine the dependence of $A_{\mathrm{FB}}^l$ on the transverse momentum and rapidity of the lepton. Combination with the asymmetry measured in the final states containing two leptons yields $A_{\mathrm{FB}}^l=(4.2\pm 2.0(\text{stat}.)\pm 1.4(\text{syst}.))\%$. The results are in agreement with predictions from the next-to-leading-order QCD generator mc@nlo, which predicts an asymmetry of $A_{\mathrm{FB}}^l=2.0\%$ for $|y_l|<1.5$.

We describe a new class of models of quantum space-time based on energetic causal sets and show that under natural conditions space-time emerges from them. These are causal sets whose causal links are labeled by energy and momentum and conservation laws are applied at events. The models are motivated by principles we propose govern microscopic physics which posit a fundamental irreversibility of time. One consequence is that each event in the history of the universe has a distinct causal relationship to the rest; this requires a novel form of dynamics which can be applied to uniquely distinctive events. We hence introduce a new kind of deterministic dynamics for a causal set in which new events are generated from pairs of progenitor events by a rule which is based on extremizing the distinctions between causal past sets of events. This dynamics is asymmetric in time, but we find evidence from numerical simulations of a $1+1$ dimensional model, that an effective dynamics emerges which restores approximate time reversal symmetry. Finally we also present a natural twistorial representation of energetic causal sets.

We study the thermodynamic behavior of static and spherically symmetric hairy black holes in massive gravity. In this case, the black hole is surrounded in a spherical cavity with a fixed temperature on the surface. It is observed that these black holes have a phase transition similar to the liquid-gas phase transition of a Van der Waals fluid. Also, by treating the cosmological constant $\mathrm{\Lambda }$ as a thermodynamic pressure $P$, we study the thermodynamic behavior of charged anti–de Sitter black holes in an ensemble with a pressure of $P$ and an electric potential $\mathrm{\Phi }$ as the natural variables. A second order phase transition is observed to take place for all the values of the electric potential $\mathrm{\Phi }$.

We investigate a quantum mechanical system on a noncommutative space for which the structure constant is explicitly time dependent. Any autonomous Hamiltonian on such a space acquires a time-dependent form in terms of the conventional canonical variables. We employ the Lewis-Riesenfeld method of invariants to construct explicit analytical solutions for the corresponding time-dependent Schrödinger equation. The eigenfunctions are expressed in terms of the solutions of variants of the nonlinear Ermakov-Pinney equation and discussed in detail for various types of background fields. We utilize the solutions to verify a generalized version of Heisenberg’s uncertainty relations for which the lower bound becomes a time-dependent function of the background fields. We study the variance for various states, including standard Glauber coherent states with their squeezed versions and Gaussian Klauder coherent states resembling a quasiclassical behavior. No type of coherent state appears to be optimal in general with regard to achieving minimal uncertainties, as this feature turns out to be background field dependent.

We study models of quintessence consisting of a number of scalar fields coupled to several dark matter components. In the case of exponential potentials the scaling solutions can be described in terms of a single field. The corresponding effective logarithmic slope and effective coupling can be written in a simple form in terms of the individual slopes and couplings of the original fields. We also investigate solutions where the scalar potential is negligible, in particular those leading to transient matter dominated solutions. Finally, we compute the evolution equations for the linear perturbations which will allow these models to be tested against current and future observational data.

We simulate the adiabatic contraction of a dark matter (DM) distribution during the process of the star formation, paying particular attention to the phase space distribution of the DM particles after the contraction. Assuming the initial uniform density and Maxwellian distribution of DM velocities, we find that the number $n(r)$ of DM particles within the radius $r$ scales like $n(r)\propto r^{1.5}$, leading to the DM density profile $\rho \propto r^{-1.5}$, in agreement with the Liouville theorem and previous numerical studies. At the same time, the number of DM particles $\nu (r)$ with periastra smaller than $r$ is parametrically larger, $\nu (r)\propto r$, implying that many particles contributing at any given moment into the density $\rho (r)$ at small $r$ have very elongated orbits and spend most of their time at distances larger than $r$. This has implications for the capture of DM by stars in the process of their formation. As a concrete example we consider the case of primordial black holes (PBHs). We show that accounting for very eccentric orbits boosts the amount of captured PBH by a factor of up to $2\times {10}^3$ depending on the PBH mass, improving correspondingly the previously derived constraints on the PBH abundance.

We calculate the neutrino yield from collisions of cosmic ray (CR) nuclei with gas using the event generator QGSJET-II. We present first the general characteristics and numerical results for the neutrino yield assuming power-law fluxes for the primary CR nuclei. Then we use three parametrizations for the Galactic CR flux to derive the neutrino yield for energies around and above the knee. The shape and the normalization of the resulting neutrino flux above $\sim 10^{14}\mathrm{eV}$ depends on the composition of the Galactic CR flux employed, but is generally dominated by its proton component. The spectral shape and magnitude of the neutrino flux suggest that the IceCube excess is not connected to interactions of Galactic sea CRs.

We discuss the generalization of the Dirac equations and spinors in momentum space to free unstable spin-$1/2$ fermions taking into account the fundamental requirement of Lorentz covariance. We derive the generalized adjoint Dirac equations and spinors, and explain the very simple relation that exists, in our formulation, between the unstable and stable cases. As an application of the generalized spinors, we evaluate the probability density. We also discuss the behavior of the generalized Dirac equations under time reversal.

The point-form version of the Bakamjian-Thomas construction is applied to the description of several semileptonic decays of mesons. Weak form factors are extracted without ambiguity for pseudoscalar-to-pseudoscalar as well as for pseudoscalar-to-vector transitions of mesons from the most general covariant decomposition of the weak current. No manifestation of cluster-separability violation appears in the form of nonphysical contributions to the structure of such a current, in contrast to what happens in the electromagnetic case. Moreover, no frame dependence is observed when we extract the form factors from the most general covariant decomposition of the current, which contrasts with analogous front-form calculations that involve vector mesons in the transition. We present our results for heavy-light meson decays, i.e. $B\to D$, as well as for $B$ and $D$ mesons decaying into $\pi$, $\rho$ and $K^{(*)}$, and perform a numerical comparison with the analogous front-form approach. Differences between point and front forms that are not seen in the heavy-quark limit of $q\overline{Q}$ systems appear. These differences are attributed to the different role that the nonvalence contributions play in the description of hadronic reactions in each form. It is argued how contributions from missing $Z$ graphs can be estimated.

We compute the isospin asymmetry distribution in the rare dileptonic decay $B\to K^{*}{\mu }^{+}{\mu }^{-}$, in the dimuon mass squared ($q^2$) region below the $J/\mathrm{\Psi }$ resonance, using nonperturbative inputs as predicted by the anti–de Sitter/quantum chromodynamics correspondence and by sum rules. We predict a positive asymmetry at $q^2=0$ which flips sign in the region $q^2\in [1,2]{\mathrm{GeV}}^2$ to remain small ($\le 2\%$) and negative for larger $q^2$. While our predictions are distinct as $q^2\to 0$, they become hardly model-dependent $q^2\ge 4{\mathrm{GeV}}^2$. We compare our predictions to the most recent LHCb data.

In the chiral symmetric phase, the polarized instanton–anti-instanton molecule pairing induces a nontrivial repulsive interaction in the isoscalar axial-vector channel. As a consequence, one unusual property is observed that in the chiral restoration phase, there is a first order phase transition for the spontaneous generation of local charge parity ($\mathcal{C}\mathcal{P}$) violation and chirality imbalance. Furthermore, it is found that external magnetic fields will lower the critical temperature for the local $\mathcal{C}\mathcal{P}$-odd phase transition and catalyze the chirality imbalance, which destroys the chiral condensate with pairing quarks between different chiralities. A reasonable strength of the repulsive interaction in the isoscalar axial-vector channel can naturally explain the inverse magnetic catalysis around the critical temperature under external magnetic fields.

In this paper, we study the prospects for determining the nature of neutrinos in the context of a supersymmetric $B-L$ extension of the standard model by using dark matter indirect detection signals and bounds on $N_{\text{eff}}$ from the cosmic microwave background data. The model contains two new dark matter candidates whose dominant annihilation channels produce more neutrinos than neutralino dark matter in the minimal supersymmetric standard model. The photon and neutrino counts may then be used to discriminate between the two models. If the dark matter comes from the $B-L$ sector, its indirect signals and impact on the cosmic microwave background can shed light on the nature of the neutrinos. When the light neutrinos are of Majorana type, the indirect neutrino signal from the Sun and the Galactic center may show a prompt neutrino box feature, as well as an earlier cutoff in both neutrino and gamma-ray energy spectra. When the light neutrinos are of Dirac type, their contribution to the effective number of neutrinos $N_{\text{eff}}$ is at a detectable level.

We propose a model based on the gauge group $SU(3{)}_C\otimes SU(3{)}_L\otimes U(1{)}_X$ with an extra $S_3$ flavor symmetry, which accounts for the lepton masses and mixing. The small active neutrino masses are generated via a double seesaw mechanism. In this scenario, the spectrum of neutrinos presents very light, light and very heavy masses. The model predicts a quasidegenerate normal hierarchy active neutrino mass spectrum and the relation $\mathrm{\Delta }{m}_{21}^2\ll \mathrm{\Delta }{m}_{31}^2$ arises from effective six-dimensional operators. The obtained neutrino mixing parameters are in agreement with the neutrino oscillation experimental data. We find $CP$ violation in neutrino oscillations with a Jarlskog invariant of about $10^{-2}$.

An infalling shell in the hard wall model provides a simple holographic model for energy injection in a confining gauge theory. Depending on its parameters, a scalar shell either collapses into a large black brane, or scatters between the hard wall and the anti–de Sitter boundary. In the scattering regime, we find numerical solutions that keep oscillating for as long as we have followed their evolution, and we provide an analytic argument that shows that a black brane can never be formed. This provides examples of states in infinite-volume field theory that never thermalize. We find that the field theory expectation value of a scalar operator keeps oscillating, with an amplitude that undergoes modulation.

Using fluid-gravity correspondence, we determine the (linearized) stress energy tensor of $\mathcal{N}=4$ super-Yang-Mills theory at strong coupling with all orders in derivatives of fluid velocity included. We find that the dissipative effects are fully encoded in the shear term and a new one, which emerges starting from the third order. We derive, for the first time, closed linear holographic renormalization group flow-type equations for (generalized) momenta-dependent viscosity functions. In the hydrodynamic regime, we obtain the stress tensor up to third order in derivative expansion analytically. We then numerically determine the viscosity functions up to large momenta. As a check of our results, we also derive the generalized Navier-Stokes equations from the Einstein equations in the dual gravity.

We construct analytic solutions in cubic open superstring field theory at higher superconformal ghost numbers. The solutions are the pure ghost ones, given by combinations of Bell polynomials of bosonized superconformal ghost fields multiplied by exponents of the bosonized ghosts. Based on the structure of the solutions, we conjecture them to describe the ghost part of collective vacuum for higher spin modes in open string theory.

We develop quantum electrodynamics into a kinetic-theory-like evolution equation for electrons, positrons and photons. To keep the “collision rules” simple, we make use of longitudinal and temporal photons in addition to the usual transverse photons. For our explicitly time-dependent approach, we introduce proper time-correlation functions. We then develop a stochastic simulation technique for solving the resulting kinetic equation. To illustrate the validity and potential of the proposed ideas, we show how a very simple simulation of the dynamics of field quanta can be used to obtain the leading-order contribution to the anomalous magnetic moment of the electron.