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<b><tt>Theory Center Seminar</tt></b><tt><br>
</tt><tt>Wed., May 28, 2014</tt><tt><br>
</tt><tt>2:00 p.m. (coffee at 1:45 p.m.)</tt><tt><br>
</tt><tt>CEBAF Center, Room L102</tt><tt><br>
<br>
</tt><tt><br>
</tt><tt>Juan Jose Sanz Cillero</tt><tt><br>
</tt><tt>Universidad Autonoma de Madrid </tt><tt><br>
</tt><tt><br>
</tt><tt><b>EW Chiral Lagrangians and the Higgs Properties at the
One-Loop Level</b></tt><tt> </tt><tt><br>
</tt><tt><br>
</tt><tt>So far LHC has found only a relatively light Higgs boson
with mass mh=126 GeV and no </tt><tt><br>
</tt><tt>beyond-SM particle has appeared yet below the TeV.
Likewise, there have been no significant</tt><tt><br>
</tt><tt>deviations in the interaction couplings with respect to the
expected SM values. EW chiral </tt><tt><br>
</tt><tt>Lagrangians are found to be, therefore, a natural and
systematic approach for the study of </tt><tt><br>
</tt><tt>this type of scenario. However, due to the tight
constraints from LHC data, one needs to go</tt><tt><br>
</tt><tt>beyond the leading order approximation in order to
disentangle possible new physics. That </tt><tt><br>
</tt><tt>is, full one-loop effects must be computed and handled in a
systematic way; tree-level </tt><tt><br>
</tt><tt>phenomenological estimates are simply not accurate enough
and miss crucial contributions. <br>
More specifically, I will discuss the one-loop calculation of the
photon-photon transition</tt><tt><br>
</tt><tt>into longitudinal ZZ and W+W-, and related observables like
e.g. the oblique parameter S, </tt><tt><br>
</tt><tt>at the one-loop level. The renormalization and running of
the relevant chiral couplings are</tt><tt><br>
</tt><tt>analyzed and a joined analysis of several observables
(photon-photon transitions, decay rates, </tt><tt><br>
</tt><tt>oblique parameters and form-factors) is proposed for the
extraction of the corresponding EW </tt><tt><br>
</tt><tt>Lagrangian parameters. In the last part of the talk, I will
look at the particular predictions</tt><tt><br>
</tt><tt>that arise in strongly-coupled models with resonances.
Strongly coupled EW models with massive</tt><tt><br>
</tt><tt>resonances are found not in conflict with the experimental
S and T as far as the masses of the</tt><tt><br>
</tt><tt>new vector and axial-vector resonance lie above the TeV
scale and the hWW coupling remains close </tt><tt><br>
</tt><tt>to the Standard Model one. All through the talk we will
employ the usual QCD tools such as effective<br>
chiral Lagrangians, Weinberg's EFT dimensional power counting and
dispersion relations.</tt><br>
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