[G12] g12/neutral pi1(1600)

[Dennis Weygand]

Reflecting on Andrea's captivating presentation yesterday, I have an idea regarding the 
neutral pi1(1600) analysis.

My premise is that the pi1(1600) decays both to rho pi and eta' pi (from E852 and VES)
In fact, eta' pi at 1600 is dominantly pi1

We are actively pursuing the PWA of the neutral 3 pi now (Carlos, Veronique, and myself)
But we can get an estimate of neutral pi1(1600) photo production cross section merely by counting how
many events we have- no PWA.

The system is highly constrained: First skim for p pi+ pi- and four gammas

one gam-gam mass must be eta
other gam-gam mass must be pi0
eta pi+ pi- must be eta' mass
0 missing mass, 0 missing four momentum

Also we can relax need for either of the neutrals so as to see it in missing mass

We then just count how many such events are visible at a mass of 1600: there should be VERY few.
Then given the acceptance (which is not hard to calculate from MC) we estimate the cross section(more likely an upper limit), and from that estimate how many pi1(1600) -> pi+ pi- pi0 there should be (VES estimates the ratio of branching ratios for the charged pi1(1600)).

Comments?

Dennis
--
Dennis Weygand
weygand at jlab.org
(757) 269-5926 (office)
(757) 870-4844 (cell)