Xi_b mass comparison June 16, 2007Posted by dorigo in news, physics, science.
The recent discovery of the new Xi_b baryon has been announced first by D0 at Fermilab on June 12th, and then in a back-to-back seminar of D0 and CDF findings, which was given yesterday at the usual place – the “wine and cheese seminar” at 1-west in Fermilab’s Wilson Hall.
The mass of the baryon is in good agreement with theoretical estimates, which – for heavy hadrons – are relatively easy to make and less error-prone, because the large mass of the heaviest quark in the bag (the bottom quark in this case, but the same goes for charm-quark hadrons to some extent) makes the system easier to model.
So let us compare the findings of D0 and CDF with theory. A picture is worth a thousand words… Here it is:
As you can see, the two measurements are in agreement with the theory bands. CDF has by far the more precise determination, thanks to its better measurement of track momenta (in particular, muons in this case).
I will have more to say soon about the details of the analysis procedure, but now I am off to a weekend in the dolomites…
Ok ok before I go: here are two plots from CDF. The first is the mass of J/psi Xi combinations – the signal which provided the mass measurement in CDF. The second is the mass of Xi_c pion combinations, one that has not yielded a mass combination yet. CDF will improve its analysis with these latter decays!