Study of the tau- --> 3h-2h+nu Decay

TL;DR

This paper measures the branching fractions of tau decays involving multiple pions and investigates the decay dynamics, revealing significant resonance contributions and deviations from phase space predictions.

Contribution

It provides precise measurements of tau decay branching fractions and observes the tau- --> f1 pi nu decay mode with detailed resonance analysis.

Findings

Branching fraction of tau- --> 3h- 2h+ nu is (8.56 +/- 0.05 +/- 0.42)E-04.

Tau- --> f1 pi nu decay observed with branching fraction (3.9 +/- 0.7 +/- 0.5)E-04.

Decay structure differs from phase space, indicating strong rho resonance influence.

Abstract

The branching fraction of the tau- --> 3h- 2h+ nu decay (h= pi, kaon) is measured with the BaBar detector to be (8.56 +/- 0.05 +/- 0.42)E-04 where the first error is statistical and the second systematic. The observed structure of this decay is significantly different from the phase space prediction, with the rho resonance playing a strong role. The decay tau- --> f1 pi nu with the f1 meson decaying to four charged pions, is observed and the branching fraction is measured to be (3.9 +/- 0.7 +/- 0.5)E-04.