Decay of the Bs0 particle and supersymmetry

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Discussion Overview

The discussion centers around the decay of the Bs0 particle, specifically the decay mode Bs0→ μ+μ-, and its implications for supersymmetry (SUSY) in the context of experimental results and theoretical predictions. Participants explore the relationship between observed decay rates, standard model (SM) predictions, and how these findings may constrain or support various SUSY models.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants note that the recent observation of the decay Bs0→ μ+μ- aligns with SM predictions, while also suggesting it is a promising avenue for exploring new effects of SUSY.
  • There is mention of previous results showing the decay rate slightly above SM expectations, but recent findings bring it closer to those predictions.
  • Some participants propose that SUSY predictions cover a broad range, including values below SM predictions, which complicates the ability to rule out SUSY.
  • Questions arise regarding the viability of specific SUSY models, such as MSSM or nMSSM, in light of current experimental constraints.
  • One participant expresses a preference for "no SUSY," arguing that any evidence for beyond the standard model (BSM) physics would be preferable to SUSY, citing its flexibility and numerous free parameters.
  • There are inquiries about rumors related to BSM physics from the 2016 LHC run and expectations for results to be announced at the Moriond conference.
  • Participants discuss the timeline for results, indicating that most searches will likely utilize the full 2016 dataset, as partial results may not be meaningful.

Areas of Agreement / Disagreement

Participants express a range of views on the implications of the decay results for SUSY, with some supporting the search for new physics through SUSY models, while others are skeptical or prefer alternative explanations. The discussion remains unresolved regarding the viability of specific SUSY models and the interpretation of the decay results.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the decay rates and the interpretations of the results in relation to SUSY models. The conversation reflects ongoing uncertainty and the need for further experimental data to clarify these issues.

kodama
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14 February 2017: First single experiment observation of the decay Bs0→ μ+μ-.
From discovery to precision measurement.
[ Branching fraction Bs0→ μ+μ- = (2.8±0.6)x10-9 ; B0→ μ+μ- < 3.4x10-10 ]

"“We love this decay because it is one of the most promising places to search for any new effects of supersymmetry,” Archilli says. “Scientists searched for this decay for more than 30 years and now we finally have the first single-experiment observation.”

the decay and lifetime is accord with SM predictions

how does supersymmetry effect decay in precision measurements and how many standard deviations does supersymmetry effects differ from SM, and from LHCb results?
 
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Nice to see that result.

##B^0 \to \mu \mu## was a bit above the SM expectation in previous results, now it is closer to the SM prediction again.

The predictions with supersymmetry cover the whole interesting range, sometimes even values below the SM prediction. You cannot rule out supersymmetry that way, but it narrows down the parameter range a lot.
 
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mfb said:
Nice to see that result.

##B^0 \to \mu \mu## was a bit above the SM expectation in previous results, now it is closer to the SM prediction again.

The predictions with supersymmetry cover the whole interesting range, sometimes even values below the SM prediction. You cannot rule out supersymmetry that way, but it narrows down the parameter range a lot.

any specific details, esp in combination with other constraints from other measurements supersymmetry? is MSSM or nMSSM still viable, or does something like nnMSSM is needed?
 
You can find specific details in the specific publications of your favorite SUSY model.
 
mfb said:
You can find specific details in the specific publications of your favorite SUSY model.
what is your favorite SUSY model? one that survives all previous constraints ?

any SUSY rumors on 2016 LHC run?
 
My favorite SUSY model is no SUSY.

Every experimental evidence for BSM physics would be better than no such evidence, no matter which theory it supports, but until we have such evidence I don't care much about SUSY. It is just too flexible with its 1xx free parameters.
 
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mfb said:
My favorite SUSY model is no SUSY.

Every experimental evidence for BSM physics would be better than no such evidence, no matter which theory it supports, but until we have such evidence I don't care much about SUSY. It is just too flexible with its 1xx free parameters.
has there been any rumors of any bsm about the 2016 lhc run, some 40 fb-1? when will results be announced?
 
First results are expected by Moriond in March. I can't (and don't want to) comment on rumors.
 
mfb said:
First results are expected by Moriond in March. I can't (and don't want to) comment on rumors.

March is only a few weeks away. will results reflect analysis of the full 2016 40 fb-1 plus 2011-2015 data, or only a small fraction of 2016 results?
 
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We had a small fraction of 2016 data for ICHEP in August already.

Most searches will probably use the full 2016 dataset (+2015). It doesn't make much sense to publish results now that are based on a part of the 2016 dataset. If the analyses are not done yet, the results will be shown later. More complex analyses need more time.
 
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