Deviation from Standard Model observed at LHCb (B->K* mu mu)

In summary, the LHCb study of the angular distribution in the decay of the B0 particle to the K* meson showed a large deviation (3.7 sigma) in one variable, P'5, in two bins. This suggests the presence of a statistical fluctuation. The analysis was based on 2011 data only, and the prediction will be improved with 2012 data. There is still speculation about what could be causing this effect, but it is an interesting difference.
  • #1
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As usual, the interpretation is still unclear, but I think it is an interesting effect.

LHCb studied the angular distributions in the decay ##B^0 \to K* \mu \mu## and presented the result at EPS2013. In one variable (called P'5) in two bins, a large deviation was found (3.7 sigma in one bin).
As many variables and bins were studied, the probability of a random fluctuation is larger than this significance suggests - LHCb gives the total probability as .5% (2.8 sigma).
The analysis was based on 2011 data only, 2012 data will increase the statistics by more than a factor of 3.

LHCb talk
Theory interpretation (based on LHCb results)
phys.org newsMy guess: theory error (as with ##\Delta A_{CP}##), or maybe a statistical fluctuation, or some measurement error. With the full LHCb dataset (and CMS, if they can measure it as well), the measurement will become much cleaner.
New physics would be the most amazing explanation, of course.
 
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  • #2
Remember that ##B_{s} \to \phi \mu \mu## has also been recently measured, and while the angular observables are "consistent" with the SM the branching ratio is measured to be half of the SM prediction. (1305.2168)
This obviously depends on the same NP operators as well as the ## \hat{O}_{7,9,10}'## opposite chirality operators. And again, the effect of any new contribution must be to lessen the width, meaning some large interference must be in play or some internal contribution that lessens the Wilson coeffs.

Hopefully it doesn't just go away with more statistics, though 2.8##\sigma## isn't all that large yet.
 
  • #3
"The uncertainties on these predictions originating from the form factor calculations are typically of the order of 20{30%."
As we know, theory uncertainties do not follow a Gaussian distribution.
Still an interesting difference, I did not see that.
 
  • #4
"I won’t believe this experiment until it is confirmed by theory!" -- Sir Arthur Eddington
 
  • #5
Here was something,

[44] arXiv:1308.1959 [pdf, other]
 

1. What is the Standard Model and why is it important?

The Standard Model is a theory in particle physics that describes the fundamental particles and their interactions. It is important because it has successfully predicted and explained many experimental observations, and is considered the most accurate description of the subatomic world to date.

2. What is the LHCb experiment and how does it relate to the Standard Model?

The LHCb (Large Hadron Collider beauty) experiment is one of the four main experiments at the Large Hadron Collider (LHC) at CERN. Its main focus is on studying the behavior of particles containing the beauty quark. The LHCb experiment is important for testing the predictions of the Standard Model and searching for any deviations or inconsistencies.

3. What is the significance of the "B->K* mu mu" decay observed at LHCb?

The "B->K* mu mu" decay is a rare process predicted by the Standard Model, where a B meson decays into a K* meson and two muons. The significance of this observation is that it provides an opportunity to test the predictions of the Standard Model and search for any deviations, which could potentially lead to the discovery of new physics beyond the Standard Model.

4. What are the potential implications of a deviation from the Standard Model in the "B->K* mu mu" decay?

If a deviation from the Standard Model is observed in the "B->K* mu mu" decay, it could indicate the presence of new particles or interactions that are not accounted for in the current theory. This could lead to a better understanding of the fundamental laws of nature and potentially open up new avenues for research in particle physics.

5. What further research is being conducted to investigate the "B->K* mu mu" decay at LHCb?

The LHCb experiment is continuously collecting data and analyzing it to further investigate the "B->K* mu mu" decay and search for any deviations from the Standard Model. Other experiments, such as Belle II and CMS, are also studying this decay process, providing complementary results and helping to confirm any potential deviations. Additionally, theoretical studies and simulations are being conducted to better understand the underlying mechanisms and potential implications of this observation.

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