[Halld-physics] Friday Journal Club

[Shepherd, Matthew]

We can now add to this list (rehashing the discussion from last fall):

Recall that conservation of C restricts what can be produced when one doesn't have charge exchange.  One thing we'd like to be able to make are states with C = +, and to do that we have to exchange something besides a pion or pomeron.  There was question about how suppressed these types of production are.  This lead to Elton's homework, and Justin's reply, which we can add to below.

> On Sep 1, 2015, at 11:06 PM, Justin Stevens <jrsteven at jlab.org> wrote:
> 
> Hi All,
> 
> On Aug 31, 2015, at 8:18 AM, Elton Smith wrote:
> 
>> 1) Are there examples of C=+ neutral states produced in photoproduction (i.e. is there evidence for rho-exchange)
> 
> Following up on this, here are a few examples if people are interested:
> 
> 1) f0(980) -> pi+ pi- (CLAS):  http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.102.102001
> 	-Observed in a moment analysis of the unpolarized pi+ pi- angular distributions
> 	-There is also a signal for f2(1270) (JPC=2++) in the same analysis 
> 
> 2) a0(980) -> pi0 eta (CB-ELSA): http://link.springer.com/article/10.1140%2Fepja%2Fi2008-10657-7
> 	-This is lower energy so not ideal for meson spectroscopy, but they did see the a0(980) in the PWA
> 
> 3) pi0 photoproduction (SLAC): http://journals.aps.org/prd/abstract/10.1103/PhysRevD.4.1937
> 	-Similar beam energy to GlueX, measured dsigma/dt and Sigma beam asymmetry

4)  Production of f0, f2, a0, and a2 evident in preliminary checks of GlueX data by Simon.

Matt