Gedalia Oram, Isidori Gino, Maltoni Fabio, Perez Gilad, Selvaggi Michele, Soreq Yotam
Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100, Israel.
Theory Division, CERN, CH1211 Geneva 23, Switzerland and Laboratori Nazionali di Frascati, INFN, Via Enrico Fermi 40, 00044 Frascati, Italy.
Phys Rev Lett. 2013 Jun 7;110(23):232002. doi: 10.1103/PhysRevLett.110.232002. Epub 2013 Jun 5.
In top-pair events where at least one of the tops decays semileptonically, the identification of the lepton charge allows us to tag not only the top quark charge but also that of the subsequent b quark. In cases where the b also decays semileptonically, the charge of the two leptons can be used to probe CP violation in heavy flavor mixing and decays. This strategy to measure CP violation is independent of those adopted so far in experiments, and can already constrain non standard model sources of CP violation with current and near future LHC data. To demonstrate the potential of this method we construct two CP asymmetries based on same-sign and opposite-sign leptons and estimate their sensitivities. This proposal opens a new window for doing precision measurements of CP violation in b and c quark physics via high p(T) processes at ATLAS and CMS.
在顶夸克对事件中，若至少有一个顶夸克通过半轻子衰变，轻子电荷的识别不仅能让我们标记顶夸克的电荷，还能标记后续b夸克的电荷。在b夸克也通过半轻子衰变的情况下，两个轻子的电荷可用于探测重味混合与衰变中的CP破坏。这种测量CP破坏的策略独立于目前实验中采用的策略，并且利用当前和不久后LHC的数据，已经能够约束CP破坏的非标准模型来源。为了展示这种方法的潜力，我们基于同号和异号轻子构建了两个CP不对称性，并估计了它们的灵敏度。该提议为通过ATLAS和CMS的高p(T)过程对b和c夸克物理中的CP破坏进行精确测量打开了一扇新窗口。
