Date: 7 March, 1978
To: SP26, SP28 Physicists
From: G. Hanson
Subject: Does tau pi + nu(tau)?
The Data Sample
I have been looking at SP17 two-prong data with a high-momentum leading particle. The basic cuts are the following:
It is clear that there is an excess of such 2-prong events with low NXSHW (0, 1, and 2) over what would be expected from "old" physics. The NXSHW distribution is shown in Figure 1 and compared with a jet model Monte Carlo which is normalized to give the correct number of 3-prong hadron events. The Monte Carlo predicts about the right number of events for NXSHW 3. Charm production contributes very little to the 2-prong, NXSHW = 0 sample because (1) it is difficult to produce both low charged and low neutral multiplicity with charm and (2) charm production does not include many events with x > 0.5. (I have done some Monte Carlo studies of high energy charm production.) These low NXSHW 2-prong events, then, are almost certainly due to +- production, unless there is a third type of "new" physics. Such events are, of course, expected assuming the usual models of decay. I therefore concentrate on the 2-prong, NXSHW = 0 sample as a source of events which are mainly due to +- production and decay.