Tuesday, 24 May 2016

Planck 2016 Liveblog: Day One Session Four

Last session of the day, BSM 1.

5:10 pm: Phenomenology of Decoupled New Physics with the SM EFT, Jeremie Quevillon

Precision measurements matching UV physics to observables.  In particular, what of Higgs as portal to new physics?  Model-independent constraints: no need to redo analyses.

Important note: must use mass-independent renormalisation scheme, otherwise higher-dimension operators will not decouple.  But then integrating out of heavy fields and matching must be done by hand.  Can be done with Feynman diagrams or by path integrals.  This technique (CDE, covariant derivative expansion) improves and simplifies this piece.

This is the rare example of a talk I'd prefer to last an hour.

Point is: can do all matching in a general language, such that any UV theory can use pre-calculated expressions to derive one-loop matching with minimal effort.

5:30 pm: Searching for heavy scales in the Electroweak Effective Theory, Joaquin Santos Blasco

EWEFT theory assuming arbitrary (non-linear) Higgs representation.  Fermions to be added.  Add bosonic singlet/triplet resonances (consider only one at a time).  Impose additional constraints for UV consistency, e.g. from Weinberg sum rules.

5:50 pm: One-loop effective Lagrangians after matching, Jose Santiago

"Goal: Generate a UV/IR dictionary (map all possible UV completions of the SM to the Wilson coefficients of the SM effective Lagrangian)" (emphasis mine).

At tree level and dimension-6, this is done?!? except for mixed contributions.  Dimensionful couplings mean states of different spin can simultaneously contribute.  To be completed soon.

One loop is next.  Many operators can only be generated at this order, not tree level (both in general and in specific models).  Number of contributions is so large that automation is necessary.  Matching in presence of linear couplings (mixings) major task.  Development of new tool MatchMaker based on FeynRules/FORM/other to do this.  Write your FeynRules model as input and the rest is taken care of.

Tensors?  In principle possible but not in the first release.
Arbitrary UV?  e.g. String RS involved parametrically light high-spin states.  OK. 

6:10 pm: Mass hierarchy and naturalness from TeV scale strong dynamics, Roberto Frezzotti

That sure was a talk.

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