Quark fragmentation in the $θ$-vacuum - High Energy Physics - PhenomenologyReportar como inadecuado




Quark fragmentation in the $θ$-vacuum - High Energy Physics - Phenomenology - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: The vacuum of Quantum Chromodynamics is a superposition of degenerate stateswith different topological numbers that are connected by tunneling the$\theta$-vacuum. The tunneling events are due to topologically non-trivialconfigurations of gauge fields e.g. the instantons that induce local $\p$-odddomains in Minkowski space-time. We study the quark fragmentation in thistopologically non-trivial QCD background. We find that even though QCD globallyconserves $\p$ and $\cp$ symmetries, two new kinds of $\p$-odd fragmentationfunctions emerge. They generate interesting dihadron correlations: one is theazimuthal angle correlation $\sim \cos\phi 1 + \phi 2$ usually referred to asthe Collins effect, and the other is the $\p$-odd correlation $\sim \sin\phi 1+ \phi 2$ that vanishes in the cross section summed over many events, butsurvives on the event-by-event basis. Using the chiral quark model we estimatethe magnitude of these new fragmentation functions. We study their experimentalmanifestations in dihadron production in $e^+e^-$ collisions, and comment onthe applicability of our approach in deep-inelastic scattering, proton-protonand heavy ion collisions.



Autor: Zhong-Bo Kang RIKEN BNL, Dmitri E. Kharzeev BNL

Fuente: https://arxiv.org/







Documentos relacionados