We study the decay of the lightest neutral Higgs boson to a charm quark pair at full one-loop level in the MSSM with non-minimal quark flavour violation (QFV). In the numerical analysis we consider mixing between the second and the third squark gener
ation and all relevant constraints from B meson data are taken into account. It is shown that the full one-loop corrected decay width can be quite sensitive to the MSSM QFV parameters due to large $tilde c - tilde t$ mixing and large trilinear couplings. After summarising the theoretical and experimental errors, we conclude that an observation of these SUSY QFV effects is possible at the ILC.
We study the effect of squark generation mixing on squark production and decays at the LHC in the Minimal Supersymmetric Standard Model (MSSM). We show that the effect can be very large despite the very strong constraints on quark flavour violation (
QFV) from experimental data on B mesons. We find that the two lightest up-type squarks ${tilde u}_{1,2}$ can have large branching ratios for the decays into $c {tildechi_1^0}$ and $t {tildechi_1^0}$ at the same time, leading to QFV signals $p p to c bar t, (t bar c)$ + missing-$E_T$ + $X$ with a significant rate. The observation of this remarkable signature would provide a powerful test of supersymmetric QFV at LHC. This could have a significant impact on the search for squarks and the determination of the underlying MSSM parameters.
HFOLD (Higgs Full One Loop Decays) is a Fortran program package for calculating all MSSM Higgs two-body decay widths and the corresponding branching ratios at full one-loop level. The package is done in the SUSY Parameter Analysis convention and supp
orts the SUSY Les Houches Accord input and output format.
We study the effects of CP violation in charged Higgs boson production $ppto t H^pm + X$ at the LHC, as well as in the charged Higgs boson decays $H^pm to t b$ and $H^pm to W^pm H_i^0$, $i=1,2,3$. The study is done in the framework of the type II com
plex Two Higgs Doublet Model (2HDM) with softly broken $Z_2$ symmetry. In this model violation of CP invariance is induced by the complex parameter $m^2_{12}$ of the tree-level Higgs potential. We calculate the CP violating rate asymmetries for $H^+$ and $H^-$ production and decays as well as for the combined processes at one-loop level and perform a detailed numerical analysis. All calculations are done with the automatic amplitude generator FeynArts and the calculational tool FormCalc, for which we have written a complete complex 2HDM model file and relevant fortran drivers. The implementation of the complex 2HDM in FeynArts and FormCalc is described. In comparison with the analogous results in the MSSM, all considered CP violating asymmetries are smaller by an order of magnitude and do not exceed 2 to 3%.
We study effects of CP violation in the associated production of a charged Higgs boson and a top quark at the LHC, $pp to tH^pm + X$. We calculate the CP violating asymmetry between the total cross section for $H^+$ and $H^-$ production at next-to-le
ading order in the MSSM, and perform a detailed numerical analysis. In the production the asymmetry is of the order of 20%. The asymmetry in the production and any subsequent decay of an on-shell charged Higgs boson is to a good approximation the sum of the asymmetry in the production and the asymmetry in the decay. We consider subsequent decays of $H^pm $ to $t b$, $ u_tau tau^pm$ and $W h^0$. In the case with $H^pm to t b$ decay, mainly due to CP violating box graphs with gluino, the asymmetry can go up to $sim$ 12%.
