Related papers: Correlations in flavor-changing tqZ couplings cons…
In models with partially composite quarks, the couplings of quarks to the Z boson generically receive non-universal corrections that are not only constrained by electroweak precision tests but also lead to flavour-changing neutral currents…
Contrary to a widely spread believe, we have demonstrated that strongly coupled electroweak models including both a light Higgs-like boson and massive spin-1 resonances are not in conflict with experimental constraints on the oblique S and…
We compile information from low-energy observables sensitive to flavor-conserving 4-fermion operators with two or four leptons. Our analysis includes data from e+e- colliders, neutrino scattering on electron or nucleon targets, atomic…
Using effective-lagrangian techniques we perform a systematic survey of the lowest-dimension effective interactions through which heavy physics might manifest itself in present experiments. We do not restrict ourselves to special classes of…
The study of the properties of the scalar boson recently discovered at the LHC (ATLAS and CMS experiments) may allow us to know whether it is well described by the Standard Model. In the case where deviations from SM predictions are…
Below the electroweak scale, new physics that violates lepton number in two units ($\Delta L = 2$) and is mediated by heavy particle exchange can be parameterized by a dimension-9 low-energy effective Lagrangian. Operators in this…
We assume that strong and electroweak interactions become strong at very high energies. With this assumption, we compute the low-energy gauge coupling constants $\alpha_i (m_Z)$ as a function of the cutoff scale, taking the supersymmetric…
We study the SU(3) gauge theory with Nf=12 flavors in the fundamental representation by use of lattice simulations with staggered fermions. With a non-improved action we observe a chiral zero-temperature (bulk) transition separating a…
A Planck-scale model that includes quantum chromodynamics and goes beyond it, is tested against observations. The model is based on a single fundamental principle. Starting with Dirac's proposal describing spin 1/2 particles as tethered…
The couplings of the electroweak effective theory contain information on the heavy-mass scales which are no-longer present in the low-energy Lagrangian. We build a general effective Lagrangian, implementing the electroweak chiral symmetry…
We examine flavour-changing neutral-current decays of the top quark, $t\to q \gamma$, $t \to qZ$, $t \to q H$, and $ t\to q g$ (with $q=u, c$), in the Alternative Left-Right Model, a left right-symmetric model featuring exotic quarks and…
We construct the six dimensional Quantum Chromodynamics (QCD) Lagrangian in a linear covariant gauge and subsequently renormalize it at two loops in the MSbar scheme. The coupling constant corresponding to the gauge interaction is…
Arguments coming from Quantum Field Theory are supplemented with a 1-loop perturbative calculation to settle the non-unitarity of mixing matrices linking renormalized mass eigenstates to bare flavor states for non-degenerate coupled…
We compute the dimension 6 effective Lagrangian arising from the tree level integration of an arbitrary number of bulk fermions in models with warped extra dimensions. The coefficients of the effective operators are written in terms of…
Walking technicolor theory attempts to realize electroweak symmetry breaking as the spontaneous chiral symmetry breakdown caused by the gauge dynamics with slowly varying gauge coupling constant and large mass anomalous dimension.…
An Effective Lagrangian description is useful for describing potential physics beyond the Standard Model. The method is illustrated by reference to interactions among the electroweak bosons ($W^\pm$ \& $Z^0$). The resulting estimates of the…
Strong-interaction physics that lies beyond the standard model may conveniently be described by an effective Lagrangian. The only genuinely gluonic CP-conserving term at dimension six is the three-gluon-field-strength operator $G^3$. This…
The initial $P$-invariance of the electroweak interaction Lagrangian together with the low-energy results of the Weinberg-Salam model is provided by a local secondary symmetry. Among the transformation parameters of this symmetry there are…
When the Standard Model is considered as an effective low-energy theory, higher dimensional interaction terms appear in the Lagrangian. Dimension-six terms have been enumerated in the classical article by Buchmueller and Wyler [3]. Although…
Using a manifestly gauge-invariant approach we show that the set of low-energy constants in the electroweak chiral Lagrangian currently used in the literature is redundant. In particular, by employing the equations of motion for the gauge…