Improving the theoretical prediction for the Bs - B̅s width difference: matrix elements of next-to-leading order ΔB = 2 operatorsChristine Davies, Judd Harrison, G Peter Lepage, Christopher Monahan, Junko Shigemitsu and Matthew WingateEPJ Web Conf., 175 (2018) 13023DOI: https://doi.org/10.1051/epjconf/201817513023