Florida State University

About: Florida State University is a education organization based out in Tallahassee, Florida, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 25117 authors who have published 65361 publications receiving 2527087 citations. The organization is also known as: FSU & Florida State.

Handbook of perturbative QCD

Abstract: The elements, theoretical basis, and experimental status of perturbative quantum chromodynamics are presented. Relevant field-theoretic methods are introduced at a nonspecialist level, along with a review of the basic ideas and methods of the parton model. This is followed by an account of the fundamental theorems of quantum chromodynamics, which generalize the parton model. Summaries of the theoretical and experimental status of the most important hard-scattering processes are then given, including electron-positron annihilation, deeply inelastic scattering, and hard hadron-hadron scattering, as induced both by electoweak interactions and by quantum chromodynamics directly. In addition, a discussion is presented of the global fitting approach to the determination of parton distributions in nucleons.

Magnetic brightening and control of dark excitons in monolayer WSe2

Abstract: Monolayer transition metal dichalcogenide crystals, as direct-gap materials with strong light-matter interactions, have attracted much recent attention. Because of their spin-polarized valence bands and a predicted spin splitting at the conduction band edges, the lowest-lying excitons in WX2 (X = S, Se) are expected to be spin-forbidden and optically dark. To date, however, there has been no direct experimental probe of these dark excitons. Here, we show how an in-plane magnetic field can brighten the dark excitons in monolayer WSe2 and permit their properties to be observed experimentally. Precise energy levels for both the neutral and charged dark excitons are obtained and compared with ab initio calculations using the GW-BSE approach. As a result of their spin configuration, the brightened dark excitons exhibit much-increased emission and valley lifetimes. These studies directly probe the excitonic spin manifold and reveal the fine spin-splitting at the conduction band edges.

Large momentum transfer production of direct photons, jets, and particles

Abstract: The theoretical framework for describing the production of direct photons in hadronic collisions is reviewed. A detailed comparison between the theoretical predictions and existing data is presented along with a critical evaluation of the various sources of theoretical uncertainty. The information available from direct-photon experiments is contrasted with that learned from jet or single-hadron production. Prospects for new types of measurements in future experiments are also presented.

Enhanced Production of Direct Photons in Au plus Au Collisions at root s(NN)=200 GeV and Implications for the Initial Temperature

Abstract: The production of e(+)e(-) pairs for m(e+e-) < 0.3 GeV/c(2) and 1< p(T) < 5 GeV/c is measured in p + p and Au + Au collisions at root s(NN) = 200 GeV. An enhanced yield above hadronic sources is observed. Treating the excess as photon internal conversions, the invariant yield of direct photons is deduced. In central Au + Au collisions, the excess of the direct photon yield over p + p is exponential in transverse momentum, with an inverse slope T = 221 +/- 19(stat) +/- 19(syst) MeV. Hydrodynamical models with initial temperatures ranging from T-init similar to 300-600 MeV at times of similar to 0.6-0.15 fm/c after the collision are in qualitative agreement with the data. Lattice QCD predicts a phase transition to quark gluon plasma at similar to 170 MeV.