Thursday, May 27, 2010 ... //

CDF refutes a D0 claim about CP-violation

Ten days ago, we wrote about the Tevatron's D0 Collaboration that claimed a 3.2-sigma evidence supporting a

new source of CP violation
using the data from dimuon events. The trustworthiness of the D0 statement was amplified by another finding by both D0 and CDF, namely a 2.12-sigma discrepancy between the observed "B_0^s" decays to "J/psi phi" and the Standard Model.

The 3.2-sigma statement is equivalent to a 99.9% confidence level while the 2.12-sigma statement is something like a 96% confidence level. But even for the higher confidence level, the proverb says that one half of the published 3-sigma results are wrong. It may actually be more than one-half and in less than ten days, we see some evidence of this general principle.

At a flavor physics and CP conference in Italy, the CDF Collaboration (see the detector on the picture) just announced the results of their own analysis of the "B_0^s" decays, using a significantly higher number of events than what they had analyzed together with D0 in the past. And the
result is that the Standard Model is doing fine.
The discrepancy is 0.8 sigma only - a smooth consistency. So the 95%-confident result about the decays has been rejected. Because the likely underlying reason behind this anomaly was probably related to the cause of the dimuon CP anomaly, it's probable that the latter - which is a 99.9% claim - is incorrect, too.
Again, you can't really build science on 2-sigma (95%) and not even 3-sigma (99.7%) claims because most of them turn out to be wrong.

Thanks to Jester at Resonaances

snail feedback (3) :

The title and the content of this post is misleading if not malicious. Let's state the facts: D0 observes a 3 s.d. anomaly from SM measuring CP violation in B mixing. CDF observes 2.2 s.d. anomaly in a different decay (Bs-> J/Psi phi). These two effects can be interpreted coherently as a crack in the SM originating from a common source of new Physics. Then the CDF effect disappears. You conclude that the D0 observation is then likely to be fake as well. That's not true: you should conclude instead that the interpretation is wrong. The D0 observation, as an experimental fact, remains. Then it should be up to other experiments (or D0 looking at other channels or reanalysing the data) to confirm or deny that effect.

Dear fsimo,

you're confused if not deliberately confusing others.

The character of the CDF observation, based on stronger data, implies that the original first D0 observation was just wrong or a fluke.

There is no coherent "crack" identified by these experiments as a "whole". The very nature is that the observations are incompatible with one another because all explanations - at least those that have been proposed - of the D0 signal as a new effect would influence the CDF measurement as well but CDF sees nothing.

Moreover, I don't know why you chose me for your obnoxious attack - it was Jester who wrote the same interpretation of the two results as the first guy.

Cheers
LM