论文标题
追踪异常的$ tqg $和$tqγ$改变风味的互动
Tracing the anomalous $tqg$ and $tqγ$ flavor changing interactions at the FCC-he
论文作者
论文摘要
我们在未来的质子电子模式（FCC-HE）中，通过$ e^-p \ to E^-p \ to E^-p \ to E^-pj $进程调查了顶部夸克与Gluon和Photon的风味变化中性电流（FCNC）耦合的可能存在。我们专注于解开可能存在的不同耦合的效果，我们利用了散射电子的存在，其角度分布对所涉及的耦合类型敏感。通过衰减轻子的角度分布访问的顶级夸克极化为识别耦合的性质提供了更多的手柄。此外，我们展示了电子束极化在区分Gluon和Photon的左手和右手耦合方面的潜力。考虑到$ e^-p $ collider $ e_ {e（p）} = 60〜（50000）$ 〜GEV在2〜Ab $^{ - 1} $集成的发光度，可以在$ 10^{ - 2} $的级别上探测耦合，并具有相应的分支机构的$ n- timper time， 10^{ - 6} $和$ {\ rm br}（t \ tocγ）\ le 1-2 \ times 10^{ - 5} $，具体取决于耦合是右手还是左手。 Gluon耦合的相应限制导致$ {\ rm br}（t \ to ug）\ le 1.7 \ times 10^{ - 5} $和$ {\ rm br}（t \ t \ to cg）\ le 3-4 \ le 3-4 \ times 10^{ - 5} $。
We investigate the possible presence of Flavor Changing Neutral Current (FCNC) couplings of the top quark with gluon and photon through $e^-p\to e^-tj$ process at the Future Circular Collider in the proton-electron mode (FCC-he). Focusing on disentangling the effects of different couplings that could be present, we exploit the presence of the scattered electron, the angular distribution of which is sensitive to the type of coupling involved. Top quark polarisation accessed through the angular distribution of the decay lepton provides additional handle in identifying the nature of the couplings. Further, we demonstrate the potential of electron beam polarisation in distinguishing the left-handed and right-handed couplings of both gluon and photon separately. Considering an $e^-p$ collider of beam energies of $E_{e(p)} = 60~(50000)$~GeV at 2~ab$^{-1}$ integrated luminosity, couplings can be probed at the level of $10^{-2}$ with the corresponding branching fractions of ${\rm BR}(t\to uγ)\le 4 - 7 \times 10^{-6}$ and ${\rm BR}(t\to cγ) \le 1-2 \times 10^{-5}$, depending on if the coupling is right-handed or left-handed. The corresponding limits on the gluon couplings lead to ${\rm BR}(t\to ug)\le 1.7 \times 10^{-5}$ and ${\rm BR}(t\to cg) \le 3-4 \times 10^{-5}$.
