Measurement of the spin density matrix for the ϱ0, K∗0(892) and F produced in Z0 decays

Abstract

The spin density matrix elements for the 0 , K 0 (892) and produced in hadronic Z 0 decays are measured in the DELPHI detector. There is no evidence To be submitted to Physics Letters B ii

Leading and higher twist contributions in semi-inclusivee+e−annihilation at high energies

“…We see that these data [17][18][19][20][21][22] indeed provide some clue to parameterize the z-dependence of these components of the fragmentation function. For the TMD session, even less data is available yet in particular when azimuthal asymmetries and polarizations are concerned.…”

“…For the semi-inclusive e + + e − → h +q + X, they are given by, 21) in contrast to those for the inclusive process e…”

“…There are also measurements on the spin alignment ρ 00 = (1 − 2S LL )/3 for vector mesons such as K * , ρ and so on [19][20][21][22]. Results for z dependences have been obtained in both cases.…”

“…Among them, a series of calculations have been carried out [41][42][43][44][45][46] using a formalism where hyperon polarization is calculated according to the origin of its production and event generator JETSET [57] based on Lund Measurements of longitudinal Lambda hyperon polarization and vector meson spin alignments have been carried out at LEP by ALEPH and OPAL Collaborations [17][18][19][20][21][22], and z dependences have been obtained. These data provides good hints for z-dependence of the corresponding components of the spin dependent session of the fragmentation function.…”

“…Many progresses have been made and summarized constantly in Review of Particle Properties [1] and also other recent reviews [2]. Much attention has been attracted recently in particular in the spin and transverse momentum dependent (TMD) sessions both in theory [3][4][5][6][7][8][9][10][11][12][13][14][15][16], and in experiment [17][18][19][20][21][22][23][24][25][26]. This provides a new window to study the fragmentation function, to test the hadronization models and to learn the properties of Quantum Chromodynamics (QCD).…”