Related papers: Decoupling relations, effective Lagrangians and lo…
We present in analytic form the matching conditions for the strong-coupling constant alpha_s^(n_f)(mu) at the flavor thresholds to four loops in the modified minimal-subtraction scheme. Taking into account the present knowledge on the…
We present a new perspective on the study of the behavior of the strong coupling $\alpha_s(Q^2)$ -- the fundamental coupling underlying the interactions between quarks and gluons as described by the Quantum Chromodynamics (QCD) -- in the…
Charged Higgs decays are discussed within an effective lagrangian extension of the two-higgs doublet model, assuming new physics appearing in the Higgs sector of this model. Low energy constrains are used to imposse bounds on certain…
CP-odd Higgs couplings to bottom and charm quarks arise in many extensions of the standard model and are of potential interest for electroweak baryogenesis. These couplings induce a contribution to the electron EDM. The experimental limit…
In extended Higgs models, a discrete symmetry is needed in the quark sector to avoid tree-level flavor-changing neutral currents. However, this is not necessary the case in the lepton sector. We consider a model in which one Higgs couples…
An evaluation of the effective QED coupling at the scale M_Z is presented. It employs the predictions of perturbative QCD for the cross section of electron positron annihilation into hadrons up to order \alpha_s^2, including the full quark…
In composite Higgs models the Higgs is a pseudo-Goldstone boson of a high-energy strong dynamics. We have constructed the effective chiral Lagrangian for a generic symmetric coset, restricting to CP-even bosonic operators up to four momenta…
In the "intense--coupling" regime all Higgs bosons of the Minimal Supersymmetric extension of the Standard Model (MSSM) are rather light and have comparable masses of O(100 GeV). They couple maximally to electroweak gauge bosons, and for…
The progress in determining the coupling constants of mesonic chiral Lagrangians is reviewed, with emphasis on the work performed in three successive European Networks (Eurodaphne I and II, Euridice). Reliable estimates of those constants…
We study the potential of the LHC and future low-energy experiments to precisely measure the underlying model parameters of a new Z' boson. We emphasize the complimentary information obtained from both on- and off-peak LHC dilepton data,…
We discuss the influence of the vacuum fluctuations of \bar{q}q pairs on low-energy constants and condensates. The analysis of the Goldstone boson masses and decay constants shows that the three-flavour condensate and some low-energy…
Probing the properties of the discovered Higgs boson may tell us whether or not it is the same particle as the one predicted by the Standard Model. To this aim we parametrize deviations of the Higgs couplings to matter from the Standard…
We present the two-loop SUSY-QCD corrections to the effective bottom Yukawa couplings within the minimal supersymmetric extension of the Standard Model. The effective Yukawa couplings include the resummation of the non-decoupling…
Depending on the Higgs-boson and top-quark masses, $M_H$ and $M_t$, the effective potential of the {\bf Standard Model} can develop a non-standard minimum for values of the field much larger than the weak scale. In those cases the standard…
We calculate the top-quark-induced three-loop corrections of O(alpha_s^2 G_F M_t^2) to the Yukawa couplings of the first five quark flavours in the framework of the minimal standard model with an intermediate-mass Higgs boson, with mass M_H…
We compute the decoupling function of the MSbar renormalized fine-structure constant up to four-loop order in perturbative QCD. The results are used in order to determine the related top-quark contributions to the Higgs-boson decay into two…
We show that both flavor-conserving and flavor-violating Yukawa couplings of the Higgs boson to first- and second-generation quarks can be probed by measuring rare decays of the form h->MV, where M denotes a vector meson and V indicates…
In the heavy quark limit, there are three independent strong axial coupling constants in chiral Lagrangians for ground-state heavy hadrons: g in the meson sector, and g_1, g_2 in the baryon sector. The coupling g_2 is extracted from recent…
We discuss the emergence of a low-energy effective theory with quarks, mesons, diquarks and baryons at vanishing and finite baryon density from first principle QCD. The present work also includes an overview on diquarks at vanishing and…
We calculate the coupling constants, $g_{\pi NS_{11}}$ and $g_{\eta NS_{11}}, using QCD sum rules in the presence of an external meson field. A covariant derivative is introduced within the S_{11} interpolating field so that in the…