Measurement of Inclusive f_1(1285) and f_1(1420) Production in Z Decays with the DELPHI Detector

TL;DR

This paper reports on the measurement of the production rates and properties of the f_1(1285) and f_1(1420) mesons in Z boson decays at LEP I, including their masses, widths, and decay modes.

Contribution

First measurement of inclusive production rates and detailed analysis of the f_1(1285) and f_1(1420) mesons in Z decays using the DELPHI detector.

Findings

Masses and widths of the states are consistent with known f_1(1285) and f_1(1420)

Partial-wave analysis supports their meson assignments

Measured production rates align with theoretical expectations

Abstract

DELPHI results are presented on the inclusive production of two (K Kbar pi)^0 states in the mass region 1.2-1.6 GeV/c^2 in hadronic Z decays at LEP I. The measured masses (widths) are 1274 +/- 6 MeV/c^2 (29 +/- 12 MeV/c^2) and 1426 +/- 6 MeV/c^2 (51 +/- 14 MeV/c^2) respectively. A partial-wave analysis of the (K Kbar pi)^0 system shows that the first peak is consistent with the I^G(J^{PC})=0^+(1^{++})/(0^{-+}) a_0(980)pi and the second with the I^G(J^{PC})=0^+(1^{++}) K^*(892)Kbar + c.c. assignments. The total hadronic production rates per hadronic Z decay are (0.165 +/- 0.051) and (0.056 +/- 0.012) respectively. These measurements are consistent with the two states being the f_1(1285) and f_1(1420) mesons.