We study the equation of state in $2+1$ flavor QCD with nonperturbatively improved Wilson quarks coupled with the renormalization group-improved Iwasaki glue. We apply the $T$-integration method to nonperturbatively calculate the equation of state by the fixed-scale approach. With the fixed-scale approach, we can purely vary the temperature on a line of constant physics without changing the system size and renormalization constants. Unlike the conventional fixed-$N_t$ approach, it is easy to keep scaling violations small at low temperature in the fixed-scale approach. We study $2+1$ flavor QCD at light quark mass corresponding to $m_{\pi }/m_{\rho }\simeq 0.63$, while the strange quark mass is chosen around the physical point. Although the light quark masses are still heavier than the physical values, our equation of state is roughly consistent with recent results with highly improved staggered quarks at large $N_t$.

$B$ physics has played a prominent role in investigations of new physics effects at low-energies. Presently, the largest discrepancy between a standard model prediction and experimental measurements appears in the branching ratio of the charged current mediated $B\to \tau {\overline{\nu }}_{\tau }$ decay, where the large $\tau$ mass lifts the helicity suppression arising in leptonic $B$ decays. Less significant systematic deviations are also observed in the semileptonic $B\to D^{(*)}\tau {\overline{\nu }}_{\tau }$ rates. Because of the rich spin structure of the final state, the decay mode $B\to D^{*}\tau {\overline{\nu }}_{\tau }$ offers a number of tests of such possible standard model deviations. We investigate the most general set of lowest dimensional effective operators leading to helicity suppressed modifications of $b\to c$ (semi)leptonic transitions. We explore such contributions to the $B\to D^{*}\tau {\overline{\nu }}_{\tau }$ decay amplitudes by determining the differential decay rate, longitudinal $D^{*}$ polarization fraction, $D^{*}-\tau$ opening angle asymmetry and the $\tau$ helicity asymmetry. We identify the size of possible new physics contributions to these observables constrained by the present $B\to D^{(*)}\tau {\overline{\nu }}_{\tau }$ rate measurements and find significant modifications are still possible in all of them. In particular, the opening angle asymmetry can be shifted by almost 30%, relative to the standard model prediction, while the $\tau$ helicity asymmetry can still deviate by as much as 80%.

The multiperipheral ladder structure of the Pomeron leads to the quite natural conclusion that the elastic slope, $B_{\mathrm{el}}$, is not a simple linear function of the logarithm of the collision energy. The existing experimental data on the diffraction cone shrinkage provide evidence in favor of such “complicated” energy dependence. An increase of the diffraction cone shrinkage with the beam energy is directly connected with the extreme rise of the total cross section (Froissart limit).

We investigate the unpolarized pion and kaon fragmentation functions, employing the nonlocal chiral-quark model, which manifests the nonlocal interactions between the quarks and pseudoscalar mesons, considering the explicit flavor-SU(3)-symmetry breaking in terms of the current-quark masses. Moreover, we study the quark distribution functions, derived from the fragmentation ones with the Drell-Yan-Levi relation. Numerical results are evaluated to higher $Q^2$ by the QCD evolution and compared with the empirical data. The ratios between the relevant valance-quark distribution functions are also discussed. It turns out that the present results are in relatively good agreement with available data and other theoretical estimations.

Employing our previous framework to treat nonperturbative effects self-consistently, including duality violations, we update the determination of the strong coupling, ${\alpha }_s$, using a modified version of the 1998 OPAL data, updated to reflect current values of exclusive-mode hadronic $\tau$-decay branching fractions. Our best $n_f=3$ values from the updated OPAL data are ${\alpha }_s(m_{\tau }^2)=0.325\pm 0.018$ and ${\alpha }_s(m_{\tau }^2)=0.347\pm 0.025$ in fixed-order and contour-improved perturbation theory, respectively. To account for nonperturbative effects, nonlinear, multiparameter fits are necessary. We have, therefore, investigated the posterior probability distribution of the model parameters underlying our fits in more detail. We find that OPAL data alone provide only weak constraints on some of the parameters needed to model duality violations, especially in the case of fits involving axial-vector channel data, making additional prior assumptions on the expected size of these parameters necessary at present. We provide evidence that this situation could be greatly improved if hadronic spectral functions based on the high-statistics BABAR and Belle data were to be made available.

A measurement of the cross section for the production of an isolated photon in association with jets in proton-proton collisions at a center-of-mass energy $\sqrt{s}=7\mathrm{TeV}$ is presented. Photons are reconstructed in the pseudorapidity range $|{\eta }^{\gamma }|<1.37$ and with a transverse energy $E_{\mathrm{T}}^{\gamma }>25\mathrm{GeV}$. Jets are reconstructed in the rapidity range $|y^{\mathrm{jet}}|<4.4$ and with a transverse momentum $p_{\mathrm{T}}^{\mathrm{jet}}>20\mathrm{GeV}$. The differential cross section $d\sigma /d{E}_{\mathrm{T}}^{\gamma }$ is measured, as a function of the photon transverse energy, for three different rapidity ranges of the leading-$p_{\mathrm{T}}$ jet: $|y^{\mathrm{jet}}|<1.2$, $1.2\le |y^{\mathrm{jet}}|<2.8$ and $2.8\le |y^{\mathrm{jet}}|<4.4$. For each rapidity configuration the same-sign $({\eta }^{\gamma }{y}^{\mathrm{jet}}\ge 0)$ and opposite-sign $({\eta }^{\gamma }{y}^{\mathrm{jet}}<0)$ cases are studied separately. The results are based on an integrated luminosity of $37{\mathrm{pb}}^{-1}$, collected with the ATLAS detector at the LHC. Next-to-leading order perturbative QCD calculations are found to be in fair agreement with the data, except for $E_{\mathrm{T}}^{\gamma }\lesssim 45\mathrm{GeV}$, where the theoretical predictions overestimate the measured cross sections.

We develop holographic prescriptions for obtaining spectral functions in nonequilibrium states and space-time dependent nonequilibrium shifts in the energy and spin of quasiparticle-like excitations. We reproduce strongly coupled versions of aspects of nonequilibrium dynamics of Fermi surfaces in Landau’s Fermi-liquid theory. We find that the incoming wave boundary condition at the horizon does not suffice to obtain a well-defined perturbative expansion for nonequilibrium observables. Our prescription, based on analysis of regularity at the horizon, allows such a perturbative expansion to be achieved nevertheless and can be precisely formulated in a universal manner independent of the nonequilibrium state, provided the state thermalizes. We also find that the nonequilibrium spectral function furnishes information about the relaxation modes of the system. Along the way, we argue that in a typical nonsupersymmetric theory with a gravity dual, there may exist a window of temperature and chemical potential at large $N$, in which a generic nonequilibrium state can be characterized by just a finitely few operators with low scaling dimensions, even far away from the hydrodynamic limit.

We analyze $U(N)$ Born-Infeld gauge theory in two spacetime dimensions. We derive the exact energy spectrum on the circle and show that it reduces to $N$ relativistic fermions on a dual space. This contrasts to the Yang-Mills case that reduces to nonrelativistic fermions. The theory admits a string theory interpretation, analogous to the one for ordinary Yang-Mills, but with higher-order string interactions. We also demonstrate that the partition function on the sphere exhibits a large-$N$ phase transition in the area and calculate the critical area. The limit in which the dimensionless coupling of the theory goes to zero corresponds to massless fermions, admits a perturbatively exact free string interpretation and exhibits no phase transition.

There is recent evidence that some SiC $X$ grains from the Murchison meteorite may contain supernova-produced $\nu$-process ${}^{11}\mathrm{B}$ and or ${}^7\mathrm{Li}$ encapsulated in the grains. The synthesis of ${}^{11}\mathrm{B}$ and ${}^7\mathrm{Li}$ via neutrino-induced nucleon emission (the $\nu$ process) in supernovas is sensitive to the neutrino mass hierarchy for finite ${sin}^{2}2{\theta }_{13}>0.001$. This sensitivity arises because, when there is 13 mixing, the average electron neutrino energy for charged-current neutrino reactions is larger for a normal mass hierarchy than for an inverted hierarchy. Recent constraints on ${\theta }_{13}$ from the Daya Bay, Double Chooz, MINOS, RENO, and T2K collaborations all suggest that indeed ${sin}^{2}2{\theta }_{13}>0.001$. We examine the possible implications of these new results based upon a Bayesian analysis of the uncertainties in the measured meteoritic material and the associated supernova nucleosynthesis models. We show that although the uncertainties are large, they hint at a marginal preference for an inverted neutrino mass hierarchy. We discuss the possibility that an analysis of more $X$ grains enriched in $\mathrm{Li}$ and $\mathrm{B}$ along with a better understanding of the relevant stellar nuclear and neutrino reactions could eventually reveal the neutrino mass hierarchy.

Boson clouds around black holes exhibit interesting physical phenomena through the Penrose process of superradiance, leading to black-hole spin-down. Axionic clouds are of particular interest, since the axion Compton wavelength could be comparable to the Schwarzschild radius, leading to the formation of “gravitational atoms” with a black-hole nucleus. These clouds collapse under certain conditions, leading to a “Bosenova.” We model the dynamics of such unstable boson clouds by a simple cellular automaton and show that it exhibits self-organized criticality. Our results suggest that the evolution through the black-hole Regge plane is due to self-organized criticality.

In this paper, we present the higher order spectra of a scalar field produced through the higher derivative interactions in the initially anisotropic universe. Although we ignore the backreaction of the scalar field on the geometry, our analysis should have much overlap with the quantum fluctuations of the inflaton field in the anisotropic universe. We also include the planar modes whose momenta are along the plane which is perpendicular to the primordial preferred direction, for which effects of the initial anisotropy are not suppressed. The presence of a negative frequency mode produces features distinguishable from the case of the de Sitter inflation. We also show that richer features appear in the trispectra due to the primordial anisotropy.

We derive the arrows of time of our universe that follow from the no-boundary theory of its quantum state (NBWF) in a minisuperspace model. Arrows of time are viewed four-dimensionally as properties of the four-dimensional Lorentzian histories of the universe. Probabilities for these histories are predicted by the NBWF. For histories with a regular “bounce” at a minimum radius fluctuations are small at the bounce and grow in the direction of expansion on either side. For recollapsing classical histories with big bang and big crunch singularities the fluctuations are small near one singularity and grow through the expansion and recontraction to the other singularity. The arrow of time defined by the growth in fluctuations thus points in one direction over the whole of a recollapsing spacetime but is bidirectional in a bouncing spacetime. We argue that the electromagnetic, thermodynamic, and psychological arrows of time are aligned with the fluctuation arrow. The implications of a bidirectional arrow of time for causality are discussed.

Based on strong-field QED in the Furry picture we use the Dirac-Volkov propagator to derive a compact expression for the differential emission probability of the two-photon Compton process in a pulsed intense laser field. The relation of real and virtual intermediate states is discussed, and the natural regularization of the on-shell contributions due to the finite laser pulse is highlighted. The inclusive two-photon spectrum is 2 orders of magnitude stronger than expected from a perturbative estimate.

We reexamine the quark-lepton complementarity (QLC) in nine angle-phase parametrizations with the latest result of a large lepton mixing angle ${\vartheta }_{13}$ from the T2K, MINOS, and Double-Chooz experiments. We find that there are still two QLC relations satisfied in P1, P4, and P6 parametrizations, whereas only one QLC relation holds in P2, P3, P5, and P9 parametrizations separately. We also work out the corresponding reparametrization-invariant forms of the QLC relations and check the resulting expressions with the experimental data. The results can be viewed as a check of the validity of the QLC relations, as well as a new perspective into the issue of seeking for the connection between quarks and leptons.

Existence of a mirror world in the Universe is a fundamental way to restore the observed parity violation in weak interactions and provides the lightest mirror nucleon as a unique GeV-scale dark matter particle candidate. The visible and mirror worlds share the same spacetime of the Universe and are connected by a unique space-inversion symmetry—the mirror parity ($P$). We conjecture that the mirror parity is respected by the fundamental interaction Lagrangian, and study its spontaneous breaking from minimizing the Higgs vacuum potential. The domain-wall problem is resolved by a unique soft-breaking linear term from the $P$-odd weak-singlet Higgs field. We also derive a constraint from big-bang nucleosynthesis. We then analyze the neutrino seesaw for both visible and mirror worlds, and demonstrate that the desired amounts of visible matter and mirror dark matter in the Universe arise from a common origin of $CP$ violation in the neutrino sector via leptogenesis. We derive the Higgs mass spectrum and Higgs couplings with gauge bosons and fermions. We show their consistency with the direct Higgs searches and the indirect precision constraints. We further study the distinctive signatures of the predicted nonstandard Higgs bosons at the LHC. Finally, we analyze the direct detections of GeV-scale mirror dark matter by the TEXONO and CDEX experiments.

We consider the production at the LHC of exotic composite leptons of charge $Q=+2e$. Such states are allowed in composite models that contain extended isospin multiplets ($I_W=1$ and $I_W=3/2$). These doubly charged leptons couple with standard model (SM) fermions via gauge interactions, thereby delineating and restricting their possible decay channels. We discuss the production cross section at the LHC of $L^{++}(pp\to L^{++},{\ell }^{-})$ and concentrate on the leptonic signature deriving from the cascade decays $L^{++}\to W^{+}{\ell }^{+}\to {\ell }^{+}{\ell }^{+}{\nu }_{\ell }$ i.e. $pp\to {\ell }^{-}({\ell }^{+}{\ell }^{+}){\nu }_{\ell }$ showing that the invariant mass distribution of the like-sign dilepton has a sharp end point corresponding to excited lepton mass $m^{*}$. We find that the $\sqrt{s}=7\mathrm{TeV}$ run is sensitive at the 3-sigma (5-sigma) level to a mass of the order of 600 GeV if $L=10{\mathrm{fb}}^{-1}$ ($L=20{\mathrm{fb}}^{-1}$). The $\sqrt{s}=14\mathrm{TeV}$ run can reach a sensitivity at 3-sigma (5-sigma) level up to $m^{*}=1\mathrm{TeV}$ for $L=20{\mathrm{fb}}^{-1}$ ($L=60{\mathrm{fb}}^{-1}$).

We determine the constraints on the isospin and hypercharge of a scalar electroweak multiplet from partial wave unitarity of tree-level scattering diagrams. The constraint from $SU(2{)}_L$ interactions yields $T\le 7/2$ (i.e., $n\le 8$) for a complex scalar multiplet and $T\le 4$ (i.e., $n\le 9$) for a real scalar multiplet, where $n=2T+1$ is the number of isospin states in the multiplet.

We study the prospects of probing large extra-dimension models at the LHC through neutral triple gauge boson production processes. In theories with extra dimensions these processes result from the exchange of a tower of massive graviton modes between the SM particles. We consider $\gamma \gamma \gamma$, $\gamma \gamma Z$, $\gamma ZZ$, and $ZZZ$ production processes, and present our results for various kinematic distributions at the LHC for $\sqrt{S}=14\mathrm{TeV}$.

We estimate the valence quark contributions for the ${\gamma }^{*}Y\to {\Lambda }^{*}$ ($Y=\Lambda$, ${\Sigma }^0$) electromagnetic transition form factors. We focus particularly on the case of ${\Lambda }^{*}=\Lambda (1670)$ as an analogue reaction with ${\gamma }^{*}N\to N(1535)$. The results are compared with those obtained from chiral unitary model, where the ${\Lambda }^{*}$ resonance is dynamically generated and thus the electromagnetic structure comes directly from the meson cloud excitation of the baryon ground states. The form factors for the case $Y={\Sigma }^0$ in particular, depend crucially on the two real phase (sign) combination, a phase between the $\Lambda$ and ${\Lambda }^{*}$ states, and the other, the phase between the $\Lambda$ and ${\Sigma }^0$ radial wave functions. Depending on the combination of these two phases, the form factors for the ${\gamma }^{*}{\Sigma }^0\to {\Lambda }^{*}$ reaction can be enhanced or suppressed. Therefore, there is a possibility to determine the phase combination by experiments.

We use the three-flavor Nambu–Jona-Lasinio model, which includes strangeness and quark physical masses in the mean field approximation, to investigate the influence of strong magnetic fields on the QCD phase diagram covering the whole $T\mathrm{\text{−}}\mu$ plane. It is found that the first order segment of the transition line becomes longer as the field strength increases so that a larger coexistence region for hadronic and quark matter should be expected for strong magnetic fields. The location of the critical end point is also affected by the presence of magnetic fields that invariably increase the temperature value at which the first order line terminates. On the other hand, at low temperatures, the critical chemical potential displays an oscillation around the $B=0$ value for magnetic fields within the ${10}^{17}-{10}^{20}\mathrm{G}$ range. These findings may have nontrivial consequences for the physics of magnetars and heavy ion collisions.