We study the role of viscosity and the effects of a magnetic field on a rotating, self-gravitating fluid, using Newtonian theory and adopting the ideal magnetohydrodynamic approximation. Our results confirm that viscosity can generate vorticity in inhomogeneous environments, while the magnetic tension can produce vorticity even in the absence of fluid pressure and density gradients. Linearizing our equations around an Einstein-de Sitter cosmology, we find that viscosity adds to the diluting effect of the universal expansion. Typically, however, the dissipative viscous effects are confined to relatively small scales. We also identify the characteristic length below which the viscous dissipation is strong and beyond which viscosity is essentially negligible. In contrast, magnetism seems to favor cosmic rotation. The magnetic presence is found to slow down the standard decay rate of linear vortices, thus leading to universes with more residual rotation than generally anticipated.

We revisit the construction of the viable parameter space of No-Scale $\mathcal{F}-SU(5)$, a model built on the $\mathcal{F}$-lipped $SU(5)\times U(1{)}_{\mathrm{X}}$ gauge group, supplemented by a pair of $\mathcal{F}$-theory derived vectorlike multiplets at the TeV scale, and the dynamically established boundary conditions of No-Scale Supergravity. Employing an updated numerical algorithm and a substantially upgraded computational engine, we significantly enhance the scope, detail and accuracy of our prior study. We sequentially apply a set of “bare-minimal” phenomenological constraints, consisting of i) the dynamically established boundary conditions of No-Scale Supergravity, ii) consistent radiative electroweak symmetry breaking, iii) precision LEP constraints on the light supersymmetric mass content, iv) the world average top-quark mass, and v) a light neutralino satisfying the 7-year WMAP cold dark-matter relic density measurement. The overlap of the viable parameter space with key rare-process limits on the branching ratio for $b\to s\gamma$ and the muon anomalous magnetic moment is identified as the “golden strip” of $\mathcal{F}-SU(5)$. A cross check for top-down theoretical consistency is provided by application of the “Super No-Scale” condition, which dynamically selects a pair of undetermined model parameters in a manner that is virtually identical to the corresponding phenomenological (driven primarily by the relic density) selection. The predicted vectorlike particles are candidates for production at the future LHC, which is furthermore sensitive to a distinctive signal of ultrahigh multiplicity hadronic jets. The lightest CP-even Higgs boson mass is predicted to be ${120}_{-1}^{+3.5}\mathrm{GeV}$, with an additional 3–4 GeV upward shift possible from radiative loops in the vectorlike multiplets. The predominantly bino flavored lightest neutralino is suitable for direct detection by the Xenon collaboration.

Real and virtual contributions to the quark-initiated forward jet vertex in QCD are calculated at next-to-leading logarithmic accuracy using Lipatov’s effective action, valid in the high-energy multi-Regge limit. A regularization of longitudinal divergencies is proposed which allows for the determination of jet observables. Agreement with previous results in the literature is found.

It is well known that $R$-parity violating supersymmetric models predict a nonzero magnetic moment for neutrinos. In this work we study the Majorana neutrino transition magnetic moments within an RpV modified minimal supergravity model. Specifically, we discuss the contributions coming from the charged Higgs bosons, Higgsinos, leptons, sleptons, charged gauge bosons, and charginos. We use the experimental results from the MUNU Collaboration to restrict the model’s parameter space. A comparison with two other types of contributions (only trilinear RpV couplings and trilinear plus neutrino-neutralino mixing) is also presented. We have found that the presently discussed processes dominate significantly, exceeding in some cases even the experimental limits.

In a recent paper, we introduced a new Little Higgs model, which contains the gauge structure $SU(2{)}^3\times U(1)$ embedded in an approximate global $SO(5)\times SO(5)$ symmetry. After breaking to the standard model, $SU(2{)}_L\times U(1{)}_Y$, this produces two heavy $Z^{\prime }$ bosons and two heavy $W^{\prime \pm }$ bosons along with a single standard model-like Higgs scalar. The unique feature of the model was that it was possible to obtain electroweak symmetry breaking and a light Higgs mass entirely from perturbative loop contributions to the Higgs effective potential. In this paper, we consider the electroweak constraints on this model, including tree and loop contributions to the universal oblique and nonoblique parameters, tree-level corrections to the $ZWW$ vertex, and tree- and loop-level corrections to $Zb\overline{b}$. The most significant corrections are positive tree-level corrections to $\widehat{S}$ and negative fermion-loop corrections to $\widehat{T}$, which require that the scale for the global symmetry breaking be $\gtrsim 2\mathrm{TeV}$, depending on the top-quark mixing parameter and the extra gauge couplings. In addition, the loop corrections to $Zb\overline{b}$ contain a divergence that must be absorbed into the coefficient of a new operator in the theory. The finite part of this $Zb\overline{b}$ correction, however, is negligible.

We give results for the Upsilon spectrum from lattice QCD using an improved version of the nonrelativistic QCD action for $b$ quarks which includes radiative corrections to kinetic terms at $\mathcal{O}(v^4)$ in the velocity expansion. We also include for the first time the effect of up, down, strange and charm quarks in the sea using “second generation” gluon field configurations from the MILC Collaboration. Using the ${\rm Y}$ $2S-1S$ splitting to determine the lattice spacing, we are able to obtain the $1P-1\overline{S}$ splitting to 1.4% and the $3S-1S$ splitting to 2.4%. Our improved result for $M({\rm Y})-M({\eta }_b)$ is 70(9) MeV and we predict $M({{\rm Y}}^{\prime })-M({\eta }_b^{\prime })=35(3)\mathrm{MeV}$. We also calculate $\pi$, $K$ and ${\eta }_s$ correlators using the highly improved staggered quark action and perform a chiral and continuum extrapolation to give values for $M_{{\eta }_s}(0.6893(12)\mathrm{GeV})$ and $f_{{\eta }_s}(0.1819(5)\mathrm{GeV})$ that allow us to tune the strange quark mass as well as providing an independent and consistent determination of the lattice spacing. Combining the nonrelativistic QCD and highly improved staggered quark analyses gives $m_b/m_s=54.7(2.5)$ and a value for the heavy quark potential parameter of $r_1=0.3209(26)\mathrm{fm}$.

We compute the quark number susceptibilities in two flavor QCD for staggered fermions by adding the chemical potential as a Lagrange multiplier for the point-split number density term. Since a lesser number of quark propagators is required at any order, this method leads to faster computations. We propose a subtraction procedure to remove the inherent undesired lattice terms and check that it works well by comparing our results with the existing ones where the elimination of these terms is analytically guaranteed. We also show that the ratios of susceptibilities are robust, opening a door for better estimates of location of the QCD critical point through the computation of the tenth and twelfth order baryon number susceptibilities without significant additional computational overload.

We perform a thorough analysis of the $VP\gamma ({\gamma }^{*})$ and $P\gamma \gamma ({\gamma }^{*})$ decays in the resonance chiral theory, where $V$ stands for the vector resonances $\rho$, $K^{*}$, $\omega$, and $\varphi$; $P$ stands for $\pi$, $K$, $\eta$, and ${\eta }^{\prime }$; and ${\gamma }^{*}$ subsequently decays into lepton pairs. Upon imposing QCD short-distance constraints on resonance couplings, the $\omega \to \pi \gamma ({\gamma }^{*})$, $\rho \to \pi \gamma ({\gamma }^{*})$, $K^{*0}\to K^0\gamma$ processes only depend on one free parameter and $\pi \to \gamma \gamma ({\gamma }^{*})$ can be completely predicted. The four mixing parameters of the $\eta –{\eta }^{\prime }$ system, i.e. two mixing angles ${\theta }_8$, ${\theta }_0$ and two decay constants $F_8$, $F_0$, are determined from radiative decays involving $\eta$ or ${\eta }^{\prime }$. The higher order low energy constants of the pseudo-Goldstone Lagrangian in the chiral anomaly sector are predicted by integrating out heavy resonances. We also predict the decay widths of $\rho \to \pi e^{+}{e}^{-}$, ${\eta }^{\prime }\to \gamma e^{+}{e}^{-}$ and $\varphi \to \eta {\mu }^{+}{\mu }^{-}$, which can be compared with the future measurement in these channels.

Experiments at the Large Hadron Collider (LHC) have measured multiplicity distributions in proton-proton collisions at a new domain of center-of-mass energy ($\sqrt{s}$) in limited pseudorapidity intervals. We analyze multiplicity distribution data of proton-proton collisions at LHC energies as measured by the Compact Muon Solenoid (CMS) experiment in terms of characteristic parameters of the negative binomial distribution (NBD) function that has played a significant role in describing multiplicity distribution data of particle production in high-energy physics experiments, in the pre-LHC energy range, in various kinds of collisions for a wide range of collision energy and for different kinematic ranges. Beside a single NBD, we apply the formalism of weighted superposition of two NBDs to examine if the multiplicity distribution data of CMS could be better explained. The weighted superposition of two NBDs indeed explains the distribution data better at the highest available LHC energy and in large intervals of phase space. The two-NBD formalism further reveals that the energy invariance of the multiplicity distribution of the soft component of particle production in hadronic collisions is valid at LHC also, as it is at RHIC and Tevatron. We analyze the data further in terms of clan parameters in the framework of the two-NBD model.

We present the first comprehensive study of hybrid baryons using lattice QCD methods. Using a large basis of composite QCD interpolating fields, we extract an extensive spectrum of baryon states and isolate those of hybrid character using their relatively large overlap onto operators which sample gluonic excitations. We consider the spectrum of nucleon and delta states at several quark masses finding a set of positive-parity hybrid baryons with quantum numbers $N_{1/2^{+}}$, $N_{1/2^{+}}$, $N_{3/2^{+}}$, $N_{3/2^{+}}$, $N_{5/2^{+}}$, and ${\Delta }_{1/2^{+}}$, ${\Delta }_{3/2^{+}}$ at an energy scale above the first band of “conventional” excited positive-parity baryons. This pattern of states is compatible with a color-octet gluonic excitation having $J^P=1^{+}$ as previously reported in the hybrid meson sector and with a comparable energy scale for the excitation, suggesting a common bound-state construction for hybrid mesons and baryons.

The relativistic Boltzmann equation for a single particle species generally implies a fixed, unchangeable equation of state that corresponds to that of an ideal gas. Real-world systems typically have more complicated equations of state which cannot be described by the Boltzmann equation. The present work derives a ’Boltzmann-like’ equation that gives rise to a conserved energy-momentum tensor with an arbitrary (but thermodynamically consistent) equation of state. Using this, a Lattice Boltzmann scheme for diagonal metric tensors and arbitrary equations of state is constructed. The scheme is verified for QCD in the Milne metric by comparing to viscous fluid dynamics.

We consider Freund-Rubin-type compactifications which are described by ($p+q$)-dimensional Einstein gravity with a positive cosmological constant and a $q$-form flux. Using perturbative expansions of Kinoshita’s ansatz for warped ${\mathrm{dS}}_p\times S^q$ and ${\mathrm{AdS}}_p\times S^q$ spacetimes, we obtain analytical solutions describing the warped branches and their respective phase spaces. These equations are given by inhomogeneous Gegenbauer differential equations which can be solved by the Green’s function method. The requirement that the Green’s functions are regular provides constraints which determine the structure of the phase space of the warped branches. We apply the perturbation results to calculate the thermodynamic variables for the warped ${\mathrm{dS}}_p\times S^q$ branch. In particular, the first law of thermodynamics can be reproduced using this method.

The Alcubierre warp drive allows a spaceship to travel at an arbitrarily large global velocity by deforming the spacetime in a bubble around the spaceship. Little is known about the interactions between massive particles and the Alcubierre warp drive, or the effects of an accelerating or decelerating warp bubble. We examine geodesics representative of the paths of null and massive particles with a range of initial velocities from $-c$ to $c$ interacting with an Alcubierre warp bubble traveling at a range of globally subluminal and superluminal velocities on both constant and variable velocity paths. The key results for null particles match what would be expected of massive test particles as they approach $\pm c$. The increase in energy for massive and null particles is calculated in terms of $v_s$, the global ship velocity, and $v_p$, the initial velocity of the particle with respect to the rest frame of the origin/destination of the ship. Particles with positive $v_p$ obtain extremely high energy and velocity and become “time locked” for the duration of their time in the bubble, experiencing very little proper time between entering and eventually leaving the bubble. When interacting with an accelerating bubble, any particles within the bubble at the time receive a velocity boost that increases or decreases the magnitude of their velocity if the particle is moving toward the front or rear of the bubble, respectively. If the bubble is decelerating, the opposite effect is observed. Thus Eulerian matter is unaffected by bubble accelerations/decelerations. The magnitude of the velocity boosts scales with the magnitude of the bubble acceleration/deceleration.

The South Pole Telescope (SPT), Atacama Cosmology Telescope (ACT), and Wilkinson Microwave Anisotropy Probe (WMAP) have each reported measurements of the cosmic microwave background’s (CMB) angular power spectrum which favor the existence of roughly one additional neutrino species, in addition to the three contained in the standard model of particle physics. Neutrinos influence the CMB by contributing to the radiation density, which alters the expansion rate of the universe during the epoch leading up to recombination. In this paper, we consider an alternative possibility that the excess kinetic energy implied by these measurements was possessed by dark matter particles that were produced through a nonthermal mechanism, such as late-time decays. In particular, we find that if a small fraction ($\lesssim 1\%$) of the dark matter in the universe today were produced through the decays of a heavy and relatively long-lived state, the expansion history of the universe can be indistinguishable from that predicted in the standard cosmological model with an additional neutrino. Furthermore, if these decays take place after the completion of big bang nucleosynthesis, this scenario can avoid tension with the value of three neutrino species preferred by measurements of the light element abundances.

We present a way to evaluate the scattering of unstable particles quantized in a finite volume with the aim of extracting physical observables for infinite volume from lattice data. We illustrate the method with the $\pi \rho$ scattering which generates dynamically the axial-vector $a_1(1260)$ resonance. Energy levels in a finite box are evaluated both considering the $\rho$ as a stable and unstable resonance and we find significant differences between both cases. We discuss how to solve the problem to get the physical scattering amplitudes in the infinite volume, and hence phase shifts, from possible lattice results on energy levels quantized inside a finite box.

We present predictions for the production cross section of t-quark pair production in association with a $Z$-boson at the next-to-leading order accuracy using matrix elements obtained from the HELAC-Oneloop package. We use the subtraction method for computing the radiative corrections as implemented in the POWHEG-Box, which was also used in several other computations of similar complexity.

The LHCb Collaboration has recently reported evidence for a $CP$ asymmetry approaching the percent level in the difference between $D^0\to {\pi }^{+}{\pi }^{-}$ and $D^0\to K^{+}{K}^{-}$. We analyze this effect as if it is due to a penguin amplitude with the weak phase of the standard model $c\to b\to u$ loop diagram, but with a $CP$-conserving enhancement as if due to the strong interactions. In such a case the magnitude and strong phase of this amplitude $P_b$ are correlated in order to fit the observed $CP$ asymmetry, and one may predict $CP$ asymmetries for a number of other singly-Cabibbo-suppressed decays of charmed mesons to a pair of pseudoscalar mesons. Nonzero $CP$ asymmetries are expected for $D^{+}\to K^{+}{\overline{K}}^0$ (the most promising channel for which a nonzero $CP$ asymmetry has not yet been reported), as well as $D^0\to {\pi }^0{\pi }^0$, $D_s^{+}\to {\pi }^{+}{K}^0$, and $D_s\to {\pi }^0{K}^{+}$. No $CP$ asymmetry is predicted for $D^{+}\to {\pi }^{+}{\pi }^0$ or $D^0\to K^0{\overline{K}}^0$ in this framework.

We present a measurement of the inclusive jet cross section using the Run II cone algorithm and data collected by the D0 experiment in $p\overline{p}$ collisions at a center-of-mass energy $\sqrt{s}=1.96\mathrm{TeV}$, corresponding to an integrated luminosity of $0.70{\mathrm{fb}}^{-1}$. The jet energy calibration and the method used to extract the inclusive jet cross section are described. We discuss the main uncertainties, which are dominated by the jet energy scale uncertainty. The results cover jet transverse momenta from 50 GeV to 600 GeV with jet rapidities in the range $-2.4$ to 2.4 and are compared to predictions using recent proton parton distribution functions. Studies of correlations between systematic uncertainties in transverse momentum and rapidity are presented.