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Re: Question On Proton Decay.



Exdperimental searches are not governed (hopefully) by theoretical
prejudices. A high energy lepton, accompanied by another track, seen in a
detector would certainly be analyzed with a variety of hypotheses as to
the nature of the process involved.

On Wed, 7 May 2003, Robert B Zannelli wrote:

Dear List Members.
I hope someone can provide some help on a question about proton decay.
In SU(5) theory the proton is predicted to decay by an exchange of a virtual
lepto quark vector boson. The decay mode favored is

P to pi0 + e+
For example

U_g to (anti)U_b(bar)

U_b to U_b

d_r to e+

With an X (+- 4/3) particle exchange between the d_r and U_g quark.

However the following decay mode (I would think) should be equally probable

P to pi+ + (anti)v_e

U_g to d_b

U_b to U_b

d_r to (anti)v_e

With a Y( +- 1/3 ) particle exchange between the d_r and U_g quark.

My question is, why has the neutral pion and positron decay mode been favored
in the search for proton decay and not the decay to a positive pion (short
lived decays to charged lepton and associated anti neutrino) and the anti
electron neutrino?
Both decay channels conserve Q_b-L charge and all other charges. Why is the
X channel apparently preferred in so far as the search for proton decay in
concerned? I think that the experimental signatures should be significantly
different since the predominate decay mode for pi+ is a muon and anti muon
neutrino. The pi0 decays into two photons.
Now I know that the simplest version of SU(5) has been falsified
because the mean proton decay time predicted should have produced observable
decay events, and no decay events have been observed to date. However with a
little SUSY fixer upper in may still be in play.

Bob Zannelli


--
"What did Barrow's lectures contain? Bourbaki writes with some
scorn that in his book in a hundred pages of the text there are about 180
drawings. (Concerning Bourbaki's books it can be said that in a thousand
pages there is not one drawing, and it is not at all clear which is
worse.)"
V. I. Arnol'd in
Huygens & Barrow, Newton & Hooke