109 research outputs found
Hadronization of a Quark-Gluon Plasma in the Chromodielectric Model
We have carried out simulations of the hadronization of a hot, ideal but
effectively massive quark-gluon gas into color neutral clusters in the
framework of the semi-classical SU(3) chromodielectric model. We have studied
the possible quark-gluon compositions of clusters as well as the final mass
distribution and spectra, aiming to obtain an insight into relations between
hadronic spectral properties and the confinement mechanism in this model.Comment: 34 pages, 37 figure
REAL-TIME DESCRIPTION OF PARTON-HADRON CONVERSION AND CONFINEMENT DYNAMICS
We propose a new and universal approach to the hadronization problem that
incorporates both partonic and hadronic degrees of freedom in their respective
domains of relevance, and that describes the conversion between them within a
kinetic field theory formulation in real time and full 7-dimensional phase
space. We construct a scale-dependent effective theory that reduces to
perturbative QCD with its scale and chiral symmetry properties at short
space-time distances, but at large distances (r > 1 fm) yields symmetry
breaking gluon and quark condensates plus hadronic excitations. The approach is
applied to the evolution of fragmenting qq~ and gg jet pairs as the system
evolves from the initial 2-jet configuration, via parton showering and cluster
formation, to the final yield of hadrons. The phenomenological implications for
e+e- -> hadrons are investigated, such as the time scale of the transition, and
its energy dependence, cluster size and mass distributions. We compare our
results for particle production and Bose-Einstein correlations with
experimental data, and find an interesting possibility of extracting the basic
parameters of the space-time evolution of the system from Bose enhancement
measurements.Comment: 51 pages, latex, 14 figures as uu-encoded postscript file
Graphene on hexagonal boron nitride as a tunable hyperbolic metamaterial
Hexagonal boron nitride (h-BN) is a natural hyperbolic material1, in which the dielectric constants are the same in the basal plane (Δ[superscript t]ââĄâΔ[superscript x]â=âΔ[superscript y]) but have opposite signs (Δ[superscript t] Δ[superscript zâ]<â0) in the normal plane (Δ[superscript z]). Owing to this property, finite-thickness slabs of h-BN act as multimode waveguides for the propagation of hyperbolic phonon polaritonsâcollective modes that originate from the coupling between photons and electric dipoles in phonons. However, control of these hyperbolic phonon polaritons modes has remained challenging, mostly because their electrodynamic properties are dictated by the crystal lattice of h-BN. Here we show, by direct nano-infrared imaging, that these hyperbolic polaritons can be effectively modulated in a van der Waals heterostructure composed of monolayer graphene on h-BN. Tunability originates from the hybridization of surface plasmon polaritons in graphene with hyperbolic phonon polaritons in h-BN so that the eigenmodes of the graphene/h-BN heterostructure are hyperbolic plasmonâphonon polaritons. The hyperbolic plasmonâphonon polaritons in graphene/h-BN suffer little from ohmic losses, making their propagation length 1.5â2.0 times greater than that of hyperbolic phonon polaritons in h-BN. The hyperbolic plasmonâphonon polaritons possess the combined virtues of surface plasmon polaritons in graphene and hyperbolic phonon polaritons in h-BN. Therefore, graphene/h-BN can be classified as an electromagnetic metamaterial as the resulting properties of these devices are not present in its constituent elements alone
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