117218759
Particle production in relativistic heavy-ion collisions with perturbative QCD
119470349
Kaon Fragmentation Function and $K/\pi$ Ratios in Nuclear Collisions
An improved leading order fragmentation functions set of kaon is proposed based on the experimental data. We compare it with currently available sets, and use it to calculate high-$p_T$ $K/\pi$ ratios in relativistic proton-proton collisions. A prediction of $K/\pi$ ratios in relativistic nucleus-nucleus collisions ($d + Au$ and $Au + Au$) at RHIC $\sqrt{s} = 200$ GeV is given.
17260983
Differences in high $p_t$ meson production between CERN SPS and RHIC heavy ion collisions
In this talk we present a perturbative QCD improved parton model calculation for light meson production in high energy heavy ion collisions. In order to describe the experimental data properly, one needs to augment the standard pQCD model by the transverse momentum distribution of partons ("intrinsic k_T"). Proton-nucleus data indicate the presence of nuclear shadowing and multiscattering effects. Further corrections are needed in nucleus-nucleus collisions to explain the observed reduction of the cross section. We introduce the idea of proton dissociation and compare our calculations with the SPS and RHIC experimental data.
119239259
Petrov type I condition and dual fluid dynamics
A bstractRecently Lysov and Strominger [arXiv:1104.5502] showed that imposing Petrov type I condition on a (p + 1)-dimensional timelike hypersurface embedded in a (p + 2)-dimensional vacuum Einstein gravity reduces the degrees of freedom in the extrinsic curvature of the hypersurface to that of a fluid on the hypersurface, and that the leading-order Einstein constraint equations in terms of the mean curvature of the embedding give the incompressible Navier–Stokes equations of the dual fluid. In this paper we show that the non-relativistic fluid dual to vacuum Einstein gravity does not satisfy the Petrov type I condition at next order, unless additional constraint such as the irrotational condition is added. In addition, we show that this procedure can be inversed to derive the non-relativistic hydrodynamics with higher order corrections through imposing the Petrov type I condition, and that some second order transport coefficients can be extracted, but the dual “Petrov type I fluid” does not match the dual fluid constructed from the geometry of vacuum Einstein gravity in the non-relativistic limit. We discuss the procedure both on the finite cutoff surface via the non-relativistic hydrodynamic expansion and on the highly accelerated surface via the near horizon expansion.
32909787
Effective Theory and Simple Completions for Neutrino Interactions
We consider all the dimension 6 operators as well as some simple extensions of the standard model that give new contributions to neutrino interactions with matter. Such interactions are usually parametrized by ϵ_(αβ), where α and β are neutrino flavor indices taking the values e, μ and τ. In the simple models we consider the ϵ_(αβ)'s are much more constrained than in the operator-based model-independent approach. Typically the ϵ_(αβ)'s are restricted to be smaller in magnitude than around 10^(−3). In some of the leptoquark models, a specific pattern for the leptoquark Yukawa couplings allows the diagonal element ϵ_(ττ) to be as large as ∼0.1, or one of ϵ_(ee), ϵ_(μμ)∼0.01. We discuss the interplay between neutrino physics and leptoquark searches at the LHC.
15694234
Warm Dark Matter in Low Scale Left-Right Theory
We investigate the viability of having dark matter in the minimal left-right symmetric theory. We find the lightest right-handed neutrino with a mass around keV as the only viable candidate consistent with a TeV scale of left-right symmetry. In order to account for the correct relic density with such low scales, the thermal overproduction of the dark matter in the early universe is compensated by a sufficient late entropy production due to late decay of heavier right-handed neutrinos. We point out that the presence of the right-handed charge-current interactions, operative around the QCD phase transition, has a crucial impact on the amount of dilution, as does the nature of the phase transition itself. A careful numerical study, employing the Boltzmann equations, reveals the existence of a narrow window for the right-handed gauge boson mass, possibly within the reach of LHC (in disagreement with a previous study). We also elaborate on a variety of astrophysical, cosmological and low energy constraints on this scenario.
119230697
Elliptic functions and maximal unitarity
Modern perturbative scattering amplitudes in gauge theories such as QCD are calculated from general principles of analyticity and unitarity without inspecting Feynman diagrams. By virtue of analyticity, amplitudes are reconstructed from their singularity structure, while unitarity ensures that residues factorize onto simpler objects. Starting from complex internal momenta and three-point amplitudes whose form is entirely xed by eld theory arguments, all trees are generated recursively
118650793
Entropic uncertainty relations under the relativistic motion
Abstract The uncertainty principle bounds our ability to simultaneously predict two incompatible observables of a quantum particle. Assisted by a quantum memory to store the particle, this uncertainty could be reduced and quantified by a new Entropic Uncertainty Relation (EUR). In this Letter, we explore how the relativistic motion of the system would affect the EUR in two sample scenarios. First, we show that the Unruh effect of an accelerating particle would surely increase the uncertainty if the system and particle entangled initially. On the other hand, the entanglement could be generated from nonuniform motion once the Unruh decoherence is prevented by utilizing the cavity. We show that, in a uncertainty game between an inertial cavity and a nonuniformly accelerated one, the uncertainty evolves periodically with respect to the duration of acceleration segment. Therefore, with properly chosen cavity parameters, the uncertainty bound could be protected. Implications of our results for gravitation are also discussed.