We attempt a description of the recently discovered Z_{c,b} states in terms of Feshbach resonances arising from the interaction between the `closed subspace of hadrocharmonium levels and the `open one of open-charm/beauty thresholds. We show how the
neutrality of the X(3872) might be understood in this scheme and provide a preliminary explanation of the pattern of the measured total widths of X,Z_{c,b}.
At the Large Hadron Collider, we prove the feasibility to detect pair production of the lightest CP-even Higgs boson h of a Type II 2-Higgs Doublet Model through the process q bar q --> Vhh (Higgs-strahlung, V=W+-,Z), in presence of two h --> b bar b
decays. We also show that, through such production and decay channels, one has direct access to the following Higgs self-couplings, thus enabling one to distinguish between a standard and the Supersymmetric version of the above model: lambda_(Hhh) -- which constrains the form of the Higgs potential -- as well as lambda_(W+- H+- h) and lambda_(Z A h) -- which are required by gauge invariance. Unfortunately, such claims cannot be extended to the Minimal Supersymmetric Standard Model, where the extraction of the same signals is impossible.
We describe the impact of the full one-loop electroweak terms of O(alpha_s alpha_EM^3) entering the electron-positron into three-jet cross-section from sqrt(s)=M_Z to TeV scale energies. We include both factorisable and non-factorisable virtual corre
ctions and photon bremsstrahlung. Their importance for the measurement of alpha_S from jet rates and shape variables is explained qualitatively and illustrated quantitatively, also in presence of b-tagging.
We describe the impact of the full one-loop EW terms of O(alpha_s alpha_EM^3) entering the electron-positron into three-jet cross-section from sqrt{s}=M_Z to TeV scale energies. We include both factorisable and non-factorisable virtual corrections, p
hoton bremsstrahlung but not the real emission of W and Z bosons. Their importance for the measurement of alpha_S from jet rates and shape variables is explained qualitatively and illustrated quantitatively.
We compute the full one-loop Electro-Weak (EW) contributions of O(alpha_S alpha_EM^3) entering the electron-positron into a quark-antiquark pair plus one gluon cross section at the Z peak and LC energies in presence of polarisation of the initial sta
te and by retaining the event orientation of the final state. We include both factorisable and non-factorisable virtual corrections, photon bremsstrahlung but not the real emission of W^pm and Z bosons. Their importance for the final state orientation is illustrated for beam polarisation setups achieved at SLC and foreseen at ILC and CLIC.
We suggest a new approach for the automatic and fully numerical evaluation of one-loop scattering amplitudes in perturbative quantum field theory. We use suitably formulated dispersion relations to perform the calculation as a convolution of tree-lev
el amplitudes. This allows to take advantage of the iterative numerical algorithms for the evaluation of leading order matrix elements.
At the Large Hadron Collider, we prove the feasibility to detect pair production of the lightest CP-even Higgs boson $h$ of Type II 2-Higgs Doublet Models through $q q^{()}to q q^{()} {hh}$ (vector-boson fusion). We also show that, through the $hhto
4b$ decay channel in presence of heavy-flavour tagging, further exploiting forward/backward jet sampling, one has direct access to the $lambda_{Hhh}$ triple Higgs coupling -- which constrains the form of the Higgs potential.
