[Halld-physics] interesting new paper

[Mark Macrae Dalton]

Hi Richard,

As it was proposed in the LOI, the experiment is not intended to test any specific model.  It would be sensitive to a difference in the proton form factor between electron and muon probes for Q2 between 5e-4 and 3e-1 GeV2.  

I now understand that a scalar boson would modify the form factor for Q2 below the mass squared of the boson.  The minimum observable mass would thus be about 20 MeV (MUSE is almost 40 MeV.)  Very heavy masses appear to be ruled out, so If the boson were above 20 MeV it would produce a broad transition in the muon form factor at its M2.  Observing such a transition would support this explanation as well and constrain the mass.

Having said that, some believe that the observation of a large radius in muonic 3He and 4He constrains the mass to be <2 MeV.

Best,
Mark Macrae Dalton



> On Sep 15, 2016, at 11:00 AM, Richard Jones <richard.t.jones at uconn.edu> wrote:
> 
> Hello all,
> 
> (Sorry Mr Moderator, will try not to send big attachments next time!)
> 
> Found this recent paper (linked below) interesting, not sure to what to make of it. Unlike most of these search plots, this one looks like the available mass/coupling space that would simultaneously explain muon g-2 and the proton radius puzzle is pretty narrow. I am curious whether GlueX might be able to close this window using the idea outlined in our June 2016 LOI?
> 
> PhysRevLett 117 101801 (2016) Sept. 2. <https://drive.google.com/file/d/0B8giqd10L9kkay1nUkdvS1o2cVU/view?usp=sharing>
> 
> 
> -Richard Jones
> 
> 
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