[Jlab-seminars] Theory Center Seminar

[Mary Fox]

*Theory Center Seminar*
Wed., May 28, 2014
2:00 p.m. (coffee at 1:45 p.m.)
CEBAF Center, Room L102


Juan Jose Sanz Cillero
Universidad Autonoma de Madrid

*EW Chiral Lagrangians and the Higgs Properties at the One-Loop Level*

So far LHC has found only a relatively light Higgs boson with mass 
mh=126 GeV and no
beyond-SM particle has appeared yet below the TeV. Likewise, there have 
been no significant
deviations in the interaction couplings with respect to the expected SM 
values. EW chiral
Lagrangians are found to be, therefore, a natural and systematic 
approach for the study of
this type of scenario. However, due to the tight constraints from LHC 
data, one needs to go
beyond the leading order approximation in order to disentangle possible 
new physics. That
is, full one-loop effects must be computed and handled in a systematic 
way; tree-level
phenomenological estimates are simply not accurate enough and miss 
crucial contributions.
More specifically, I will discuss the one-loop calculation of the 
photon-photon transition
into longitudinal ZZ and W+W-, and related observables like e.g. the 
oblique parameter S,
at the one-loop level. The renormalization and running of the relevant 
chiral couplings are
analyzed and a joined analysis of several observables (photon-photon 
transitions, decay rates,
oblique parameters and form-factors) is proposed for the extraction of 
the corresponding EW
Lagrangian parameters. In the last part of the talk, I will look at the 
particular predictions
that arise in strongly-coupled models with resonances. Strongly coupled 
EW models with massive
resonances are found not in conflict with the experimental S and T as 
far as the masses of the
new vector and axial-vector resonance lie above the TeV scale and the 
hWW coupling remains close
to the Standard Model one. All through the talk we will employ the usual 
QCD tools such as effective
chiral Lagrangians, Weinberg's EFT dimensional power counting and 
dispersion relations.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://mailman.jlab.org/pipermail/jlab-seminars/attachments/20140523/393be6dc/attachment.html