Poissonian limit of soft gluon multiplicity

Abstract

It is shown that the gluons produced with small transverse momenta $k_{\perp }$ inside a jet ($k_{\perp }<k_{\perp }^{cut}$, $k_{\perp }^{cut}\to 0$) are independently emitted from the primary parton, as QCD coherence suppresses their showering. Consequently, the low $k_{\perp }$ gluons follow a Poisson distribution, very much like the soft photons radiated by a charged particle in QED. On the contrary, the distribution of gluons with limited absolute momenta $|\vec{k}|<k^{cut}$ remains non-Poissonian even for small $k^{cut}$. It will be interesting to find out to what extent this perturbative prediction for partons survives the hadronization process.

Comments: LaTeX2e, 41 pages, 8 figures