On the concept of local parton-hadron duality

Abstract

E the !& decade jet physics h s bee. i&~sive!y .?-.died zt ete-afid hadro~ic colliders. With the start of LEP activity a wealth of new data has become available (see, for example, [l]). They show that the global features of hadronic jets systems (multiplicities, angular patterns of particle flows, inclusive energy spectra etc), calcnlated at the parton level, agree very well with the measured ones. This convincingly demonstrates the dominant role of the perturbative (PT) phase of jet evolution and strongly supports the hypothesis of local parton-hadron duality (LPHD) [Zj 31; Such a local duality is naturally connected with the 'preconfinement' properties [4] of the QCD cascades. Together with the modified leading logarithmic approximation (MLLA)

QCD Matrix Elements + Parton Showers

“…[5]- [12]. Here we suggest a method in which the domains of applicability of matrix elements and parton showers are clearly separated at a given value y ini of the jet resolution variable y cut , defined according to the k T -algorithm [13,14] for jet clustering (sometimes called the Durham algorithm). Recall that two objects i and j are resolved according to the k T -algorithm if y ij ≡ 2 min{E 2 i , E 2 j }(1 − cos θ ij )/Q 2 > y cut ,…”

Rates for rapidity gap Higgs production

“…A remarkable advantage of the double-rapidity-gap signature for the H → bb events is that here the H → bb signal/bb background ratio is strongly enhanced due to the colour factors, gluon polarization selection and the spin 1 2 nature of the quarks [12]. First, the background bb-dijet rate is suppressed due to the absence of the colour-octet bb-state.…”

“…One possibility, which at first sight looks attractive, is the search for the Higgs boson in double rapidity gap events at proton colliders, see, for example, [1]- [9]. This has become more important since LEP is no longer available for Higgs hunting.…”

Measurement of triple gauge-boson couplings at 172 GeV

“…The resulting e ciency was found to be 86% with a purity of 94%. The remaining events are forced into two jets using the Durham (P scheme) jet algorithm [18], disregarding the candidate for the lepton originating from one of the W bosons. Finally, the energies of the two jets are required to be greater than 10 GeV each.…”