We suggest that specific thermal low-frequency g-modes can exist in superfluid neutron stars. They can be excited in the matter with a nonzero gradient of entropy per electron. We determine the Brunt-Väisälä frequency for these modes and demonstrate that they can be unstable with respect to convection. The criterion for the instability onset (analogue of the well-known Schwarzschild criterion) is derived. It is very sensitive to the equation of state and a model of nucleon superfluidity. In particular, convection may occur for both positive and negative temperature gradients. Our results may have interesting implications for neutron star cooling and seismology.

In the forthcoming high-luminosity phase at the LHC, many of the most interesting measurements for precision QCD studies are hampered by conditions of large pileup, particularly at not very high transverse momenta. We study observables based on measuring ratios of color-singlet currents via Higgs boson and Drell-Yan production, which may be accessed also at large pileup, and used for an experimental program on QCD physics of gluon fusion processes in the LHC high-luminosity runs. We present results of Monte Carlo calculations for a few specific examples.

With the LHC discovery of a 125 GeV Higgs-like boson, we study the gravitational interaction of the Higgs boson via the unique dimension-four operator involving the Higgs doublet and scalar curvature, $\xi H^{†}H\mathcal{R}$, with nonminimal coupling $\xi$. This Higgs portal term can be transformed away in the Einstein frame and induces gauge-invariant effective interactions in the Higgs sector. We study the weak boson scattering in the Einstein frame and explicitly demonstrate the longitudinal-Goldstone boson equivalence theorem in the presence of $\xi$ coupling. With these, we derive a perturbative unitarity bound on the Higgs gravitational coupling $\xi$ in the Einstein frame, which is stronger than that inferred from the LHC Higgs measurements. We further study $\xi$-dependent weak boson scattering cross sections at the TeV scale and propose a new LHC probe of Higgs-gravity coupling $\xi$ via weak boson scattering experiments.

In this work, we build a covariant basis for operators acting on the $(j,0)\oplus (0,j)$ Lorentz group representations. The construction is based on an analysis of the covariant properties of the parity operator, which for these representations transforms as the completely temporal component of a symmetrical tensor of rank $2j$. The covariant properties of parity involve the Jordan algebra of anticommutators of the Lorentz group generators which unlike the Lie algebra is not universal. We make the construction explicit for $j=1/2$, 1 and $3/2$, reproducing well-known results for the $j=1/2$ case. We provide an algorithm for the corresponding calculations for arbitrary $j$. This covariant basis provides an inventory of all the possible interaction terms for gauge and nongauge theories of fields for these representations. In particular, it supplies a single second-rank antisymmetric structure, which in the Poincaré projector formalism implies a single Pauli term arising from gauge interactions and a single (free) parameter $g$, the gyromagnetic factor. This simple structure predicts that for an elementary particle in this formalism all multipole moments, $Q_E^l$ and $Q_M^l$, are dictated by the complete algebraic structure of the Lorentz generators and the value of $g$. We explicitly calculate the multipole moments, for arbitrary $j$ up to $l=8$. Comparing with results in the literature we find that only the electric charge and magnetic moment of a spin $j$ particle are independent of the Lorentz representation under which it transforms, all higher multipoles being representation dependent. Finally we show that the propagation of the corresponding spin $j$ waves in an electromagnetic background is causal.

We present an analysis of production and signature of neutral Higgs boson ($H_2^0$) on the version of the 3-3-1 model containing heavy leptons at the Large Hadron Collider. We studied the possibility to identify it using the respective branching ratios. Cross section are given for the collider energy, $\sqrt{s}=14\mathrm{TeV}$. Event rates and significances are discussed for two possible values of integrated luminosity, $300{\mathrm{fb}}^{-1}$ and $3000{\mathrm{fb}}^{-1}$.

Dihadron fragmentation functions (DiFF) provide a vast amount of information on the intricate details of the parton hadronization process. Moreover, they provide unique access to the “clean” extraction of nucleon transversity parton distribution functions in semi-inclusive deep inelastic two-hadron production processes with a transversely polarized target. The Nambu–Jona-Lasinio–jet model has been extended for calculations of light and strange quark unpolarized DiFFs to pions, kaons and several vector mesons. This is accomplished by using the probabilistic interpretation of the DiFFs and employing the Nambu–Jona-Lasinio–jet hadronization model in the Monte Carlo simulations, which includes the transverse momentum of the produced hadrons. The strong decays of the vector mesons and the subsequent modification of the pseudoscalar meson DiFFs are also considered. The resulting pseudoscalar meson DiFFs are strongly influenced by the decays of the relevant vector mesons. This is because of the large combinatorial factors involved in counting the number of hadron pairs that include the decay products. The evolution of the DiFFs from the model scale to a typical experimental scale has also been performed.

We calculate second and fourth order quark number susceptibilities for $2+1$ flavor QCD in the high temperature region. In our study, we use two improved staggered fermion formulations, namely, the highly improved staggered quark formulation and the so-called p4 formulation, as well as several lattice spacings. Second order quark number susceptibilities are calculated using both improved staggered fermion formulations, and we show that in the continuum limit the two formulations give consistent results. The fourth order quark number susceptibilities are studied only using the p4 formulation and at nonzero lattice spacings. We compare our results on quark number susceptibilities with recent weak coupling calculations and find that these agree reasonably well with the lattice calculations within the estimated uncertainties.

In this work, we study the newly observed $D_J(3000)$ and $D_J^{*}(3000)$ through the analysis of mass spectrum and calculation of the corresponding two-body strong decay behaviors. Our results show that $D_J(3000)$ and $D_J^{*}(3000)$ are explained as the $2P(1^{+})$ and $2{}^{3}P_0$ states in the $D$ meson family, respectively, which is supported by the calculated masses of these two states and their decay behaviors. As a byproduct, the decay behaviors of $3{}^{1}S_0$, $3{}^{3}S_1$, $2D(2^{-})$, $2{}^{3}D_1$, $2D^{\prime }(2^{-})$, $2{}^{3}D_3$, $2P^{\prime }(1^{+})$, $2{}^{3}P_2$, $1F(3^{+})$, $1{}^{3}F_2$, $1F^{\prime }(3^{+})$, and $1{}^{3}F_4$ states are also given, which will be helpful to further experimentally study mixings of these $D$ mesons, too.

We describe the main features of recent LHC data on elastic $pp$ scattering through a simple parametrization to the amplitude, inspired by a model proposed by Barger and Phillips in 1973, comprised of two exponentials with a relative phase. Despite its simplicity, this parametrization reproduces two essential aspects of the elastic differential cross section: the well-known precipitous descent in the forward direction and a sharp “dip” structure. To include a complete description of data sets near $-t=0$, we correct the original parametrization. We examine two possibilities: the presence of the two-pion threshold singularity or a multiplicative factor reflecting the proton form factor. We find good descriptions of LHC7 and ISR data in either case. The form-factor model allows simple predictions for higher energies through asymptotic theorems and asymptotic sum rules in impact parameter space. We present predictions for this model at higher LHC energies, which can be used to test whether asymptotia is reached. The black-disk limit in this model is seen to be reached only for $\sqrt{s}\sim {10}^6\mathrm{TeV}$.

In this paper we document the modifications introduced to the previous version of the resonance chiral Lagrangian current [Phys. Rev. D 86, 113008 (2012)] of the ${\tau }^{\pm }\to {\pi }^{\pm }{\pi }^{\pm }{\pi }^{\mp }{\nu }_{\tau }$ decay which enable the one-dimensional distributions measured by the BABAR Collaboration to be well modeled. The main change required to model the data is the addition of the $\sigma$ resonance. Systematic errors, theoretical and experimental ones, limitations due to fits of one-dimensional distributions only, and resulting difficulties and statistical/systematic errors for fitted parameters are addressed. The current and fitting environment is ready for comparisons with the fully exclusive experimental data. The present result for ${\tau }^{\pm }\to {\pi }^{\pm }{\pi }^{\pm }{\pi }^{\mp }{\nu }_{\tau }$ is encouraging for work on other $\tau$ decay modes and resonance chiral Lagrangian based currents.

We derive the corrections induced by the $W$-boson propagator to the differential rates of the leptonic decay of a polarized muon and $\tau$ lepton. Results are presented both for decays inclusive of inner bremsstrahlung as well as for radiative ones, when a photon emitted in the decay process is measured. The numerical effect of these corrections is discussed. The definition of the Fermi constant $G_F$ is briefly reviewed.

We have exposed a dual-phase liquid argon time projection chamber (LAr-TPC) to a low energy pulsed narrow-band neutron beam, produced at the Notre Dame Institute for Structure and Nuclear Astrophysics, to study the scintillation light yield of recoiling nuclei. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the LAr-TPC and to select the energy of the recoiling nuclei. We report the observation of a significant dependence (up to 32%) on the drift field of liquid argon scintillation from nuclear recoils of energies between 10.8 and 49.9 keV. The field dependence is stronger at lower energies. Since it is the first measurement of such an effect in liquid argon, this observation is important because, to date, estimates of the sensitivity of LAr-TPC dark matter searches are based on the assumption that the electric field has only a small effect on the light yield from nuclear recoils.

We report measurements of the inclusive transverse momentum ($p_T$) distribution of centrally produced $K_S^0$, $K^{\star \pm }(892)$, and ${\varphi }^0(1020)$ mesons up to $p_T=10\mathrm{GeV}/c$ in minimum bias events, and $K_S^0$ and ${\Lambda }^0$ particles up to $p_T=20\mathrm{GeV}/c$ in jets with transverse energy between 25 and 160 GeV in $p\overline{p}$ collisions. The data were taken with the CDF II detector at the Fermilab Tevatron at $\sqrt{s}=1.96\mathrm{TeV}$. We find that as $p_T$ increases, the $p_T$ slopes of the three mesons ($K_S^0$, $K^{\star \pm }$, and $\varphi$) are similar. And using our previous ${\Lambda }^0$ results from minimum bias events, we show that the ratio of ${\Lambda }^0$ to $K_S^0$ as a function of $p_T$ in minimum bias events becomes similar to the fairly constant ratio in jets at $p_T\sim 5\mathrm{GeV}/c$. This suggests that the particles with $p_T\gtrsim 5\mathrm{GeV}/c$ in minimum bias events are from “soft” jets, and that the $p_T$ slope of particles in jets is insensitive to light quark flavor ($u$, $d$, or $s$) and to the number of valence quarks. We also find that for $p_T\lesssim 4\mathrm{GeV}$ relatively more ${\Lambda }^0$ baryons are produced in minimum bias events than in jets.

We report on a search for a dijet resonance in events with only two or three jets and a large imbalance in the total event transverse momentum. This search is sensitive to the possible production of a new particle in association with a $W$ or $Z$ boson, where the boson decays leptonically with one or more neutrinos in the final state. We use the full data set collected by the CDF II detector at the Tevatron collider at a proton-antiproton center-of-mass energy of 1.96 TeV. These data correspond to an integrated luminosity of $9.1{\mathrm{fb}}^{-1}$. We study the invariant mass distribution of the two jets with highest transverse energy. We find good agreement between data and standard model background expectations and measure the combined cross section for $WW$, $WZ$, and $ZZ$ production to be ${13.8}_{-2.7}^{+3.0}\mathrm{pb}$. No significant anomalies are observed in the mass spectrum, and 95% credibility level upper limits are set on the production rates of a potential new particle in association with a $W$ or $Z$ boson.

We construct a perturbative framework for understanding the collision of solitons (more precisely, solitary waves) in relativistic scalar field theories. Our perturbative framework is based on the suppression of the space-time interaction area proportional to $1/(\gamma v)$, where $v$ is the relative velocity of an incoming solitary wave and $\gamma =1/\sqrt{1-v^2}\gg 1$. We calculate the leading order results for collisions of ($1+1$) dimensional kinks in periodic potentials and provide explicit, closed form expressions for the phase shift and the velocity change after the collisions. We find excellent agreement between our results and detailed numerical simulations. Crucially, our perturbation series is controlled by a kinematic parameter and hence not restricted to small deviations around integrable cases such as the Sine-Gordon model.

We study the Hamiltonian structure of the general parity-invariant model of three-dimensional gravity with propagating torsion, with eight parameters in the Lagrangian. In the scalar sector, containing scalar or pseudoscalar modes with respect to maximally symmetric background, the phenomenon of constraint bifurcation is observed and analyzed. The stability of the Hamiltonian structure under linearization is used to identify dynamically acceptable values of parameters.

We investigate the cosmological predictions of several $f(T)$ models, with up to two parameters, at both the background and the perturbation levels. Using current cosmological observations (geometric supernovae type Ia, cosmic microwave background and baryonic acoustic oscillation and dynamical growth data) we impose constraints on the distortion parameter, which quantifies the deviation of these models from the concordance $\Lambda$ cosmology at the background level. In addition we constrain the growth index $\gamma$ predicted in the context of these models using the latest perturbation growth data in the context of three parametrizations for $\gamma$. The evolution of the best fit effective Newton constant, which incorporates the $f(T)$-gravity effects, is also obtained along with the corresponding $1\sigma$ error regions. We show that all the viable parameter sectors of the $f(T)$ gravity models considered practically reduce these models to $\Lambda \mathrm{CDM}$. Thus, the degrees of freedom that open up to $\Lambda \mathrm{CDM}$ in the context of $f(T)$ gravity models are not utilized by the cosmological data leading to an overall disfavor of these models.

We present a TeV-scale left-right ultraviolet completion of the type-I seesaw for neutrino masses based on the $SU(2{)}_L\times SU(2{)}_R\times U(1{)}_{B-L}$ gauge group without parity, which leads to “large” light-heavy neutrino mixing while keeping the neutrino masses small in a natural manner guaranteed by discrete symmetries. We point out specific observable implications of this class of models if the $SU(2{)}_R$-breaking scale is of order 5 TeV, in searches for lepton flavor violating processes such as $\mu \to e\gamma$, $\mu \to 3e$ and $\mu \to e$ conversion in nuclei, and lepton number violating processes such as neutrinoless double beta decay as well as at the LHC. In particular, if the upper limit on $\mathrm{BR}(\mu \to e\gamma )$ improves by 1 order of magnitude, a large range of the parameters of the model would be ruled out.

The accuracy of the numerical findings of [G. Lukes-Gerakopoulos, Phys. Rev. D 86, 044013 (2012)], regarding the existence of additional first integrals in the Zipoy-Voorhees space-time, was recently questioned [A. J. Maciejewski, M. Przybylska, and T. Stachowiak, Phys. Rev. D 88, 064003 (2013)]. In this Comment, it is shown that the discrepancy between the results of Lukes-Gerakopoulos; Maciejewski et al. is not due to issues related to numerical accuracy, as claimed in Maciejewski et al., but due to a different choice of coordinates used in Maciejewski et al.