On D→Xul+l- within the Standard Model and frameworks like the littlest Higgs model with T Parity

The D→Xul+l- transitions--branching ratios, forward-backward (FB) asymmetry AFBc, the CP asymmetry ACPc, and the CP asymmetry in the forward-backward asymmetry AFBCP--have two sources: for D± they represent a pure ΔC=1 and ΔQ=0 current interaction whereas neutral D mesons can also communicate via their antihadron. Standard model (SM) contributions to BR(D→Xul+l-) come primarily from long distance dynamics, which overshadow short distance contributions by several orders of magnitude; still they fall much below the present upper experimental bounds. Even the SM contributions to AFBc, ACPc, and AFBCP are tiny, quite unlike in beauty hadrons. The branching ratios are hardly dented by contributions from the littlest Higgs models with T parity (LHT) even in the short distance regime, let alone in the SM long distances dynamics. Yet the asymmetries AFBc, ACPc, and AFBCP in these new physics models can be enhanced over SM predictions, as they arise purely from short distance dynamics; this can occur, in particular, for AFBc and AFBCP, which get enhanced by orders of magnitudes. Even such enhancements hardly reach absolute sizes for observable experimental effects for AFBc and ACPc. However, LHT contributions to AFBCP could be measured in experiments like the LHCb and the SuperB Collaboration. These results lead us to draw further conclusions on flavor-changing neutral-current interactions within LHT-like models through some simple scaling arguments that encapsulate the essence of flavor dynamics in and beyond the standard model.