The like-sign dimuon asymmetry and New Physics

TL;DR

This paper investigates whether extensions of the Standard Model can explain the D0 collaboration's observed large like-sign dimuon asymmetry, but finds that such models are insufficient to fully account for the measurement.

Contribution

The paper analyzes generic Standard Model extensions with enlarged CKM matrices to assess their ability to explain the D0 asymmetry anomaly.

Findings

Extensions can enhance individual semileptonic asymmetries

Enhancements are insufficient to match D0 measurement

Standard Model extensions alone cannot fully explain the observed asymmetry

Abstract

The measurement by the D0 collaboration of a large like-sign dimuon asymmetry deviates significantly from Standard Model expectations. New Physics may be invoked to account for such a deviation. We analyse how generic extensions of the Standard Model where the Cabibbo-Kobayashi-Maskawa $3\times 3$ mixing matrix is enlarged can accommodate a significant enhancement of $A^b_{SL}$ with respect to standard expectations through enhancements of the individual semileptonic asymmetries $A^d_{SL}$ and $A^s_{SL}$ in the $B^0_d$-$\bar B^0_d$ and $B^0_s$-$\bar B^0_s$ systems. The potential enhancement reachable in this class of scenario is, nevertheless, insufficient to reproduce the D0 measurement.