Some people seem to be puzzled by the update of the R(K) and R(K*) measurements presented today by the LHCb collaboration. Renato Quagliani made a great presentation explaining it all, but in case you missed it, I asked ChatGPT for a clarification and here is what I’ve got in response:
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The LHCb experiment at the Large Hadron Collider (LHC) is a particle physics experiment that studies the properties of subatomic particles, including the behavior of mesons, which are composed of quarks and antiquarks. One of the measurements made by the LHCb experiment is the ratio of the decay rates of a particular type of meson called a K meson, denoted as R(K).
In 2013, the LHCb collaboration published a measurement of R(K) that showed a discrepancy with the Standard Model prediction for certain ranges of the meson’s decay products. This result generated a lot of interest and discussion within the particle physics community, as it suggested the possibility of new physics beyond the Standard Model.
However, subsequent measurements of R(K) by the LHCb collaboration have refined and updated the original result, and the current measurement is consistent with the Standard Model prediction within the experimental uncertainties. It is not uncommon for experimental measurements to be refined or revised as more data is collected and analyzed, and this is what happened in the case of the LHCb R(K) measurement.
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Not bad
When I asked for more details it basically said go read the paper, which clearly indicates it didn’t read it yet
Unfortunately this is, as Guillelmo Gomez-Ceballos puts it, one of those major results where you do not open a bottle of Champagne after the presentation.
The results are compatible with the SM at 0.2 σ level.
