28 research outputs found
On the renormalization of the electroweak chiral Lagrangian with a Higgs
We consider the scalar sector of the effective non-linear electroweak
Lagrangian with a light "Higgs" particle, up to four derivatives in the chiral
expansion. The complete off-shell renormalization procedure is implemented,
including one loop corrections stemming from the leading two-derivative terms,
for finite Higgs mass. This determines the complete set of independent chiral
invariant scalar counterterms required for consistency; these include bosonic
operators often disregarded. Furthermore, new counterterms involving the Higgs
particle which are apparently chiral non-invariant are identified in the
perturbative analysis. A novel general parametrization of the pseudoescalar
field redefinitions is proposed, which reduces to the various usual ones for
specific values of its parameter; the non-local field redefinitions reabsorbing
all chiral non-invariant counterterms are then explicitly determined. The
physical results translate into renormalization group equations which may be
useful when comparing future Higgs data at different energies
Renormalization group evolution of Higgs effective field theory
The one-loop renormalization of the action for a set Dirac fermions and a set
of scalars spanning an arbitrary manifold coupled via Yukawa-like and gauge
interactions is presented. The computation is performed with functional methods
and in a geometric formalism that preserves at all stages the symmetries of the
action. The result is then applied to Higgs effective field theory to obtain
the renormalization group evolution. In the Standard Model limit of this EFT
the RGE equations collapse into a smaller linearly independent set; this allows
to probe the dynamics of the scalar discovered at LHC via de-correlations in
the running of couplings
The linear–non-linear frontier for the Goldstone Higgs
The minimal SO(5) / SO(4) -model is used as a template for the ultraviolet completion of scenarios in which the Higgs particle is a low-energy remnant of some high-energy dynamics, enjoying a (pseudo) Nambu–Goldstone-boson ancestry. Varying the mass allows one to sweep from the perturbative regime to the customary non-linear implementations. The low-energy benchmark effective non-linear Lagrangian for bosons and fermions is obtained, determining as well the operator coefficients including linear corrections. At first order in the latter, three effective bosonic operators emerge which are independent of the explicit soft breaking assumed. The Higgs couplings to vector bosons and fermions turn out to be quite universal: the linear corrections are proportional to the explicit symmetry-breaking parameters. Furthermore, we define an effective Yukawa operator which allows a simple parametrization and comparison of different heavy-fermion ultraviolet completions. In addition, one particular fermionic completion is explored in detail, obtaining the corresponding leading low-energy fermionic operators