We study the symmetries of the three-heavy-quark system under exchange of the quark fields within the effective field theory framework of potential nonrelativistic QCD. The symmetries constrain the form of the matching coefficients in the effective theory. We then focus on the color-singlet sector and determine the so far unknown leading ultrasoft contribution to the static potential, which is of order ${\alpha }_{\mathrm{s}}^4\ln \mu$, and consequently to the static energy, which is of order ${\alpha }_{\mathrm{s}}^4\ln {\alpha }_{\mathrm{s}}$. Finally, in the case of an equilateral geometry, we solve the renormalization group equations and resum the leading ultrasoft logarithms for the static potential of three quarks in a color singlet, octet and decuplet representation.

When high-energy single-hadron production takes place inside an identified jet, there are important correlations between the fragmentation and phase-space cuts. For example, when one-hadron yields are measured in on-resonance $B$-factory data, a cut on the thrust event shape $T$ is required to remove the large $b$-quark contribution. This leads to a dijet final-state restriction for the light-quark fragmentation process. Here, we complete our analysis of unpolarized fragmentation of (light) quarks and gluons to a light hadron $h$ with energy fraction $z$ in $e^{+}{e}^{-}\to \mathrm{\text{dijet}}+h$ at the center-of-mass energy $Q=10.58\mathrm{GeV}$. In addition to the next-to-next-to-leading order resummation of the logarithms of $1-T$, we include the next-to-leading order nonsingular $\mathcal{O}(1-T)$ contribution to the cross section, the resummation of threshold logarithms of $1-z$, and the leading nonperturbative contribution to the soft function. Our results for the correlations between fragmentation and the thrust cut are presented in a way that can be directly tested against $B$-factory data. These correlations are also observed in Pythia but are surprisingly smaller at next-to-leading order.

Magnetic moments of charged and neutral mesons are calculated with the use of the relativistic Hamiltonian derived from the path integral form of the $q_1{\overline{q}}_2$ Green’s function. The magnetic moments are shown to be expressed via the average quark energies, which are defined by the following fundamental quantities: the string tension $\sigma$, the current quark masses, and the strong coupling constant ${\alpha }_s$. Resulting values for vector, axial, and tensor light and $K$ mesons agree well with all available lattice data.

Neutrino masses and mixings can be generated in many different ways, with some of these scenarios featuring new physics at energy scales relevant for Large Hadron Collider searches. A systematic approach to constructing a large class of models for Majorana neutrinos may be founded upon a list of gauge-invariant effective operators—formed from quarks, leptons and the Higgs doublet—that violate lepton-number conservation by two units. By opening up these operators in all possible ways consistent with some minimality assumptions, a complete catalog of a class of minimal radiative neutrino mass models may be produced. In this paper we present an analysis of Feynman diagram topologies relevant for the ultraviolet completions of these effective operators and collect these into a simple recipe that can be used to generate radiative neutrino mass models. Since high mass-dimension effective operators are suppressed by powers of the scale of new physics, many of the resulting models can be meaningfully tested at the Large Hadron Collider.

We analyze geometrical scaling (GS) of negative pion multiplicity $p_{\mathrm{T}}$ distributions at NA61/SHINE energies. We show that even though NA61/SHINE energies are low, one may expect to find GS in the particle spectra. We argue that qualitative behavior of ratios of multiplicities at different energies is in agreement with a simple picture of GS which is violated for $p_{\mathrm{T}}$ smaller than some nonperturbative scale $\Lambda$ and when larger Bjorken $x$ of one of the scattering patrons crosses $x_{\max }$ above which a gluonic cloud becomes dilute and quark degrees of freedom become important.

We a simplified holographic model of chiral symmetry breaking in the gauge theory. The chiral condensate is represented by a single scalar field in anti–de Sitter (AdS) space, with the gauge dynamics input through radial dependence of its mass, representing the running of the anomalous dimension of the $\overline{q}q$ operator. We discuss simple examples of the chiral transition out of the conformal window when the infrared value of the anomalous dimension, ${\gamma }_m$, is tuned to one (equivalently the AdS-scalar mass squared is tuned to the Breitenlohner-Freedman [BF] bound of -4). The outputs of the model are the masses of the $\overline{q}q$ scalar meson bound states. We show in an explicit example that if the gradient of the running of the anomalous dimension falls to zero at the scale where the BF bound violation occurs, so that the theory becomes near conformal, then the theory possesses a technidilaton state that is parametrically lighter than the dynamically generated quark mass. Indeed the full spectrum of excited meson states also become light (relative to the techniquark mass) as they approach a conformal spectrum.

By means of a triple master action we deduce here a linearized version of the “new massive gravity” (NMG) in arbitrary dimensions. The theory contains a 4th-order and a 2nd-order term in derivatives. The 4th-order term is invariant under a generalized Weyl symmetry. The action is formulated in terms of a traceless ${\eta }^{\mu \nu }{\Omega }_{\mu \nu \rho }=0$ mixed symmetry tensor ${\Omega }_{\mu \nu \rho }=-{\Omega }_{\mu \rho \nu }$ and corresponds to the massive Fierz-Pauli action with the replacement $e_{\mu \nu }={\partial }^{\rho }{\Omega }_{\mu \nu \rho }$. The linearized 3D and 4D NMG theories are recovered via the invertible maps ${\Omega }_{\mu \nu \rho }=ϵ_{\nu \rho }{}^{\beta }{h}_{\beta \mu }$ and ${\Omega }_{\mu \nu \rho }=ϵ_{\nu \rho }{}^{\gamma \delta }{T}_{[\gamma \delta ]\mu }$ respectively. The properties $h_{\mu \nu }=h_{\nu \mu }$ and $T_{[[\gamma \delta ]\mu ]}=0$ follow from the traceless restriction. The equations of motion of the linearized NMG theory can be written as zero “curvature” conditions ${\partial }_{\nu }{T}_{\rho \mu }-{\partial }_{\rho }{T}_{\nu \mu }=0$ in arbitrary dimensions.

We analyze the relation between the present (and foreseen) bounds on matter stability and the presence of TeV-scale color octet scalar states in nonsupersymmetric $SO(10)$ grand unification with one adjoint Higgs representation triggering the symmetry breaking. This scenario, discarded long ago due to tree-level tachyonic instabilities appearing in all phenomenologically viable breaking patterns, has been recently revived at the quantum level. By including the relevant two-loop corrections we find a tight correlation between the octet mass and the unification scale which either requires a light color octet scalar within the reach of the LHC or, alternatively, a proton lifetime accessible to the forthcoming megaton-scale facilities.

We study the dual fluid on a finite cutoff surface outside the black brane horizon in the third order Lovelock gravity. Using nonrelativistic long-wavelength expansion, we obtain the incompressible Navier-Stokes equations of dual fluid with external force density on the finite cutoff surface. The viscosity to entropy density ratio $\eta /s$ is independent of the cutoff surface and does not get modification from the third order Lovelock gravity influence. The obtained ratio agrees with the results obtained by using other methods, such as the Kubo formula at the AdS boundary and the membrane paradigm at the horizon in the third order Lovelock gravity. These results can be related by Wilson renormalization group flow. However the kinematic viscosity receives correction from the third order Lovelock term. We show that the equivalence between the isentropic flow of the fluid and the radial component of the gravitational equation observed in the Einstein and Gauss-Bonnet gravities also holds in the third order Lovelock gravity. This generalization brings more understanding of relating the gravity theory to the dual fluid.

We introduce a new approach to modified gravity which generalizes the recently proposed hybrid metric-Palatini gravity. The gravitational action is taken to depend on a general function of both the metric and Palatini curvature scalars. The dynamical equivalence with a nonminimally coupled biscalar field gravitational theory is proved. The evolution of cosmological solutions is studied using dynamical systems techniques.

A possible cause of the late-time cosmic acceleration is an exotic fluid with an equation of state lying within the phantom regime, i.e., $w=p/\rho <-1$. This violates the null energy condition, which is a fundamental ingredient in wormhole physics. Thus, cosmic phantom energy may, in principle, provide a natural fluid to support wormholes. In this work, we find new asymptotically flat wormhole solutions supported by the phantom energy equation of state, consequently extending previous solutions. Thus, there is no need to surgically paste the interior wormhole geometry to an exterior vacuum spacetime. In the first example, we carefully construct a specific shape function, where the energy density and pressures vanish at large distances as $\sim 1/r^n$, with $n>0$. We also consider the “volume integral quantifier,” which provides useful information regarding the total amount of energy-condition-violating matter, and show that, in principle, it is possible to construct asymptotically flat wormhole solutions with an arbitrary small amount of energy-condition-violating matter. In the second example, we analyze two equations of state, i.e., $p_r=p_r(\rho )$ and $p_t=p_t(\rho )$, where we consider a specific integrability condition in order to obtain exact asymptotically flat wormhole solutions. In the final example, we postulate a smooth energy density profile, possessing a maximum at the throat and vanishing at spatial infinity.

We study the process of decoherence induced by the presence of an environment in acoustic black holes, using the open quantum system approach, thus extending previous work. We focus on the ion trap model but the formalism is general to any experimental implementation. We compute the decoherence time for that setup. We find that a quantum-to-classical transition occurs during the measurement and we propose improved parameters to avoid such a feature. We provide analytic estimations for both zero and finite temperature. We also study the entanglement between the Hawking-pair phonons for an acoustic black hole while in contact with a reservoir, through the quantum correlations, showing that they remain strongly correlated for small enough times and temperatures. We use the stochastic formalism and the method of characteristic to solve the field wave equation.

The matching of our epoch of existence with the approximate equality of the dark energy and dark matter densities is an apparent further fine-tuning, beyond the already troubling 120 orders of magnitude that separate dark energy from the Planck scale. In this paper I will argue that this coincidence is not a fine-tuning problem, but instead an artifact of anthropic selection. Rather than assuming observations are equally likely in all epochs, one should insist that measurements of a quantity be typical amongst all such measurements. As a consequence, particular observations will reflect the epoch in which they are most easily made. In the specific case of cosmology, most measurements of dark energy and dark matter will be done during an epoch when large numbers of linear modes are available to observers, so we should not be surprised to be living at such a time. This idea is made precise in a particular model for the probability distribution for $r\equiv \min (\frac{{\Omega }_m}{{\Omega }_{\Lambda }},\frac{{\Omega }_{\Lambda }}{{\Omega }_m})$, where it is shown that if $p(r)\sim [N(r){]}^b$ [where $N(r)$ is the number of linear modes, and $b$ is some arbitrary positive power], the probability that $r$ is greater than its observed value of 0.4 is close to 1. Thus the cosmological coincidence is no longer problematic.

We develop a relativistic lattice Boltzmann model capable of describing relativistic fluid dynamics at ultra-high velocities, with Lorentz factors up to $\gamma \sim 10$. To this purpose, we first build a new lattice kinetic scheme by expanding the Maxwell-Jüttner distribution function in an orthogonal basis of polynomials and applying an appropriate quadrature, providing the discrete versions of the relativistic Boltzmann equation and the equilibrium distribution. To achieve ultra-high velocities, we include a flux limiter scheme, and introduce the bulk viscosity by a suitable extension of the discrete relativistic Boltzmann equation. The model is validated by performing simulations of shock waves in viscous quark-gluon plasmas and comparing with existing models, finding very good agreement. To the best of our knowledge, we for the first time successfully simulate viscous shock waves in the highly relativistic regime. Moreover, we show that our model can also be used for near-inviscid flows even at very high velocities. Finally, as an astrophysical application, we simulate a relativistic shock wave, generated by, say, a supernova explosion, colliding with a massive interstellar cloud, e.g., molecular gas.

Previous studies of the semilinear wave equation in Minkowski space have shown a type of critical behavior in which large initial data collapse to singularity formation due to nonlinearities while small initial data does not. Numerical solutions in spherically symmetric anti–de Sitter space are presented here which suggest that, in contrast, even small initial data collapse eventually. Such behavior appears analogous to the recent result of Bizoń and Rostworowski [Phys. Rev. Lett. 107, 031102, 2011] that found that even weak, scalar initial data collapse gravitationally to black hole formation via a weakly turbulent instability. Furthermore, the imposition of a reflecting boundary condition in the bulk introduces a cutoff, below which initial data fails to collapse. This threshold appears to arise because of the dispersion introduced by the boundary condition.

We present a QCD sum rule analysis for the newly observed resonance $X_c(3250)$ by assuming it to be a $D_0^{*}(2400)N$ molecular state. Technically, contributions of operators up to dimension 12 are included in the operator product expansion (OPE). We find that it is difficult to find the conventional OPE convergence in this work. By releasing the rigid OPE convergence criterion, one could find that the OPE convergence is still under control in the present work, and the numerical result for the $D_0^{*}(2400)N$ state is $3.18\pm 0.51\mathrm{GeV}$, which is in agreement with the experimental data of $X_c(3250)$. In view of that, the conventional OPE convergence is not obtained here; thus only weak conclusions can be drawn regarding the explanation of $X_c(3250)$ in terms of a $D_0^{*}(2400)N$ molecular state. As a byproduct, the mass for the bottom counterpart ${\overline{B}}_0^{*}N$ state is predicted to be $6.50\pm 0.49\mathrm{GeV}$.

Supersymmetric SO(10) grand unified models with renormalizable Yukawa couplings involving 10, 126, and 120 Higgs fields have been shown to give a very economical theory for understanding quark-lepton flavor in a unified framework. In previous papers, we showed how nucleon decay can be suppressed in these models without invoking cancellation, by choice of Yukawa flavor texture within a type II seesaw framework for neutrinos that explains all mixings and masses including the recently observed “large” ${\theta }_{13}$. In this followup paper, we extend our earlier work to the case of type I seesaw and show that the recently measured large ${\theta }_{13}$ can be accommodated in this case while suppressing proton decay. We then point out that the two cases (type I and II) lead to different testable predictions for $B(\mu \to e+\gamma )$ and $B(\tau \to \mu (e)+\gamma )$ as well as different flavor final states in nucleon decay. In particular, we find that for the type I seesaw case, $B(\tau \to \mu +\gamma )$ can be observable while at the same time suppressing $B(\mu \to e+\gamma )$, whereas in the type II seesaw case, $B(\tau \to \mu +\gamma )$ is always suppressed whereas $B(\mu \to e+\gamma )$ is observable.

We report a new analysis of lattice simulation results for octet baryon masses in $2+1$-flavor QCD, with an emphasis on a precise determination of the pion-nucleon and strangeness nucleon sigma terms. A controlled chiral extrapolation of a recent PACS-CS Collaboration data set yields baryon masses which exhibit remarkable agreement both with experimental values at the physical point and with the results of independent lattice QCD simulations at unphysical meson masses. Using the Feynman-Hellmann relation, we evaluate sigma commutators for all octet baryons. The small statistical uncertainty and considerably smaller model dependence allows a significantly more precise determination of the pion-nucleon sigma commutator and the strangeness sigma term than hitherto possible, subject to an unresolved issue concerning the lattice scale setting.