Search Talks

The D0 Collaboration recently reported a 3.2sigma deviation from the standard model prediction in the like-sign dimuon asymmetry. I will discuss the implications of this anomaly assuming that new physics contributes only to B_{d,s} mixing. The data allow universal new physics with similar contributions relative to the SM in the B_d and B_s systems, but favors a larger deviation in B_s than in B_d mixing. The general minimal flavor violation framework with flavor diagonal CP violating phases can account for the former and remarkably even for the latter case. This observation makes it simpler to speculate about which extensions with general flavor structure may also fit the data.

Graphene-like materials provide a unique opportunity to explore quantum-relativistic phenomena in a condensed matter laboratory. Interesting phenomena associated with the internal degrees of freedom, spin and valley, including quantum spin-Hall effect, have been theoretically proposed, but could not be observed so far largely due to disorder and density inhonogeneity. We show that weak magnetic field breaks the symmetries that protect flavor (spin, valley) degeneracy, and induces large bulk non-quantized flavor-Hall effect in graphene. The effect occurs due to flavor splitting which generates the imbalance of the Hall resistivities of the two flavor species. At the Dirac point, flavor-Hall effect is greatly enhanced due to anomalous magnetotransport of Dirac-like carriers. The flavor-Hall effect is robust in the presence of disorder and interactions, and can serve as a hallmark of the quasi-relativistic carriers in the system. It manifests itself in large nonlocal transport mediated by long-lived flavor currents, as well as in flavor injection and accumulation experiments. Recent experimental observation of the giant nonlocal transport in graphene following our prediction opens up new opportunities for creating and manipulating flavor currents. Our work also shows that nonlocal electric transport provides a tool to study neutral modes in solid-states systems.