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High Energy Physics Seminar

Tuesday, June 25, 2024
4:00pm to 5:00pm
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Online and In-Person Event
Unexplained "invisible" final states in the charmonium region
Glennys Farrar, NYU,

With collaborators Qiming Li and Changzheng Yuan of the BESIII collaboration, we have compared published precision BESIII measurements of the cross section for e+e—>mu+mu-  in the E_cm = 3.8-4.6 GeV range, to predictions based on measured R_had data using dispersion relations.  The consistency is poor (p-value <0.012).  However allowing for resonance contributions not seen in R_had gives an excellent fit.  The 4.6-sigma state required at 4421 MeV is consistent with its being the known resonance at the same mass, psi(4415), with only about half of its decays are being counted in the R_had analysis.   The 3.2 sigma structure at 4211 MeV, if confirmed, points to a new, very narrow resonance.  I will discuss the analysis we performed, as well as some elements of the event selection criteria in the R_had measurements that could in principle cause final states to be missed.  

As of now, no compelling explanation has been found for such a significant portion of final states being missed or what the state at 4211 MeV might be.  I am eager to brainstorm about what could be going on.  One question we might be able to settle is whether a BSM explanation for the 4211 state can be excluded based on other experimental constraints.  (Note these have nothing apparently to do with the sexaquark Dark Matter proposal which prompted me to undertake this analysis.)

The talk is in 469 Lauritsen.

Contact for Zoom link.