Fakultät für Mathematik und Physik, Albert-Ludwigs-Universität, Freiburg i.Br., Germany.
Phys Rev Lett. 2012 Aug 17;109(7):071801. doi: 10.1103/PhysRevLett.109.071801. Epub 2012 Aug 16.
A search is reported for the pair production of a new quark b' with at least one b' decaying to a Z boson and a bottom quark. The data, corresponding to 2.0 fb(-1) of integrated luminosity, were collected from pp collisions at √s = 7 TeV with the ATLAS detector at the CERN Large Hadron Collider. Using events with a b-tagged jet and a Z boson reconstructed from opposite-charge electrons, the mass distribution of large transverse momentum b' candidates is tested for an enhancement. No evidence for a b' signal is detected in the observed mass distribution, resulting in the exclusion at a 95% confidence level of b' quarks with masses m (b') < 400 GeV that decay entirely via b' → Z+b. In the case of a vectorlike singlet b' mixing solely with the third standard model generation, masses m(b') < 358 GeV are excluded.
据报道，正在寻找新夸克 b' 的对产生，其中至少有一个 b' 衰变为 Z 玻色子和一个底夸克。该数据是使用 ATLAS 探测器在 CERN 大型强子对撞机上以 √s = 7 TeV 的质子-质子对撞收集的，对应于 2.0 fb(-1) 的积分亮度。利用带有 b 标记喷流和由相反电荷电子重建的 Z 玻色子的事件，测试了大横动量 b' 候选物的质量分布是否存在增强。在观察到的质量分布中未检测到 b' 信号的证据，导致在 95%置信水平下排除了完全通过 b' → Z+b 衰变的质量 m (b') < 400 GeV 的 b' 夸克。在与第三代标准模型完全混合的类矢量单态 b' 的情况下，排除了质量 m(b') < 358 GeV 的情况。
