Precision electroweak physics by ATLAS
Posted: Fri Jan 27, 2017 9:28 pm
Two nice recent measurements from ATLAS:
W+, W-, Z cross sections (7 TeV) - with an uncertainty of just 0.6% and 0.3% for W and Z, respectively, and with many precise differential cross section values. The additional luminosity uncertainty of 1.9% is dominant, but not that relevant for the main result: The proton has a strong sea quark contribution from strange-quarks.
This sea quark contribution is the largest uncertainty in the W mass measurement, where ATLAS reached the precision of the best Tevatron result already (0.025% uncertainty) - with further improvements they will probably beat the previous world average. Reaching that so early was quite unexpected. While the previous world average was a bit higher than the electroweak fit based on other measurements, the new measurement is right in between the old measurements and the prediction. The SM fits again.
The improved strange sea quark measurement will probably allow updates of a few older measurements and help future measurements, theory predictions and MC generators.
W+, W-, Z cross sections (7 TeV) - with an uncertainty of just 0.6% and 0.3% for W and Z, respectively, and with many precise differential cross section values. The additional luminosity uncertainty of 1.9% is dominant, but not that relevant for the main result: The proton has a strong sea quark contribution from strange-quarks.
This sea quark contribution is the largest uncertainty in the W mass measurement, where ATLAS reached the precision of the best Tevatron result already (0.025% uncertainty) - with further improvements they will probably beat the previous world average. Reaching that so early was quite unexpected. While the previous world average was a bit higher than the electroweak fit based on other measurements, the new measurement is right in between the old measurements and the prediction. The SM fits again.
The improved strange sea quark measurement will probably allow updates of a few older measurements and help future measurements, theory predictions and MC generators.