Analysis of direct CP violation in B−→D0Ds−,D0D−B^- \to D^0 D_s^-, D^0 D^- decays

We investigate the possibility of observing the direct CP violation in the decay modes $B^- \to D^0 D_s^-$ and $D^0 D^-$ within the Standard Model. Including the contributions arising from the tree, annihilation, QCD as well as electroweak penguins with both time- and space-like components, we find that the direct CP asymmetry in $B^- \to D^0 D_s^-$ is very small $\sim 0.2$ % but in $B^- \to D^0 D^-$ decay it can be as large as 4%. Approximately $10^7$ charged $B$ mesons are required to experimentally observe the CP asymmetry parameter for the later case. Since this is easily accessible with the currently running B factories, the decay mode $B^- \to D^0 D^-$ may be pursued to look for CP violation.Comment: Latex, 14 page

Single polymer gating of channels under a solvent gradient

We study the effect of a gradient of solvent quality on the coil-globule transition for a polymer in a narrow pore. A simple self-attracting self-avoiding walk model of a polymer in solution shows that the variation in the strength of interaction across the pore leads the system to go from one regime (good solvent) to the other (poor solvent) across the channel. This may be thought analogous to thermophoresis, where the polymer goes from the hot region to the cold region under the temperature gradient. The behavior of short chains is studied using exact enumeration whilst the behavior of long chains is studied using transfer matrix techniques. The distribution of the monomer density across the layer suggests that a gate-like effect can be created, with potential applications as a sensor.Comment: 5 Pages, 7 Figures, Accepted in Phys. Rev. E (2013