Naturally Small $x_s$?

Abstract

Within the Standard Model, $x_s$ (the mixing parameter in the $B_s-{\bar{B}}_s$ system) is constrained to the range $7\le x_s\le 40$. We point out that if New Physics contributes significantly to $x_d$ (the mixing parameter in the $B_d-{\bar{B}}_d$ system), then $2\le x_s\le 7$ is possible without any fine-tuned cancellations between the Standard Model and the New Physics contributions.

Comments: 9 pages, WIS-94/9/Feb-PH