Measurement of Tau Branching Ratios.
Several branching ratios for (tau) decays have been measured using e('+)e('-) (--->) (tau)('+)(tau)(' -) events. The data were accumulated with the TPC/Two-Gamma detector at the SLAC e('+)e('-) storage ring PEP and corresponded to an integrated luminosity of 77 pb('-1) at a center-of -mass energy of 29 GeV. One data sample consisted of events which had final state topologies containing one-charged -particle opposite to three-charged-particle, while the second data sample consisted of events in which both (tau)'s decayed to only one charged particle each. The one- and three-charged-particle inclusive branching ratios of the (tau) decay were measured to be (84.6 (+OR-) 0.9(,-1.0)('+0.9))% and 15.4 (+OR-) 0.9(, -0.9)('+1.0))%. The branching ratios of the two leptonic decays and two semihadronic decays of the (tau), B((tau) (--->) e(nu)(,e)(nu)(,(tau))), B((tau) (--->) (mu)(nu)(,(mu))(nu)(,(tau))), B((tau) (--->) one charged hadron + neutrals), and B((tau) (--->) (pi)('-) + neutrals), were measured to be (19.4 (+OR-) 1.3(,-1.6)('+1.8))%, (18.2 (+OR-) 1.2(,-0.4)('+0.5))%, (47.0 (+OR-) 1.2(,-0.9)('+0.4))%, and (45.5 (+OR-) 1.2(, -0.9)('0.5))%, respectively. Using particle identification by dE/dx in the TPC, charged K mesons in one-prong (tau) decays were identified. With the identified K mesons the branching ratios of Cabibbo-suppressed (tau) decays, B((tau)(' - )(--->) K('-)(nu)(,(tau)) + N(,(gamma))) with N (GREATERTHEQ) 0 and N (GREATERTHEQ) 1, were measured to be (1.5 (+OR -) 0.3 (+OR-) 0.2)% and (1.1 (+OR-) 0.4 (+OR-) 0.2)%. A search was also made for K*('(+OR-))(892)'s by reconstructing the decay, K*('(+OR-) )(--->) K(,8)('0)(pi)('(+OR-)), with the three (pi)'s in three-prong (tau) decays. The branching ratio of the Cabibbo-suppressed (tau) decay, B((tau)(' - )(--->) K*('-)(892)(nu)(,(tau))), was measured to be (1.4 (+OR-) 0.9)%. In addition to these branching ratios, an upper limit on the branching ratio of the rare (tau) decay, B((tau)('(+OR-) )(--->) K('(+OR-)) + 2 charged + neutrals), of 0.6% (90% C.L.) was set for the first time. The quoted errors are the combined statistical and systematic errors.
- Pub Date:
- Physics: Elementary Particles and High Energy