Constraints on unparticle interaction from b → sγ

We study unparticle effects on b → sγ. The unparticle contributions can contribute significantly to both left- and right-handed chirality amplitudes. Using available experimental data and SM calculation for B → Xsγ, we obtain constraints on various vector and scalar unparticle couplings. We find that the constraints sensitively depend on the unparticle dimension dU. For dU close to one, the constraints can be very stringent. The constraints become weak when dU is increased. In general the constraints on scalar unparticle couplings are weaker than those for vector unparticle couplings. Sizeable coupling strength for unparticles with quarks is still allowed. We also show that polarization measurement in Λb → Λγ can further constrain the couplings.