论文标题
通过LHC的光子 - 光子过程生产重粒子对
Production of heavy particle pairs via photon-photon processes at the LHC
论文作者
论文摘要
我们讨论了$ W^+ W^ - $ Pairs和$ t \ bar t $ Quark-Antiquark对质子proton碰撞造成的质子碰撞，这是由两光融合引起的，包括传入光子的横向动量。光子的未集成非弹性通量（与质子分离有关）是根据深度非弹性结构功能的现代参数化计算的，其范围为$ x $和$ q^2 $。我们专注于单质质子分离的过程。高度激发的残余系统强调产生可以在量热计中否决的颗粒。我们计算相关的间隙存活因子。差距存活因子取决于过程，残余系统的质量和碰撞能量。双重解离（DD）碰撞的残余碎片引起的快速差距存活因子小于单个解离（SD）过程。我们观察到近似分解：$ s_ {r，dd} \ of s_ {r，sd}^2 $当施加快速性否决时。对于$ w^+w^ - $最终状态，当施加快速差距要求时，残留的碎片会导致横截面的驯服。同样，对于$ t \ bar t $ quark-antiquark对，这种条件逆转了考虑到这种情况时观察到的层次结构。我们的结果表明，对于生产诸如$ t $ quark和$ \ bar t $ Antiquark之类的重物，分离系统附加的光子的虚拟性非常大（$ q^2 <$ 10 $^{4} $ gev $^2 $）。对于$ w^+ w^ - $系统也观察到类似的效果。
We discuss production of $W^+ W^-$ pairs and $t \bar t$ quark-antiquark pairs in proton-proton collisions induced by two-photon fusion including transverse momenta of incoming photons. The unintegrated inelastic fluxes (related to proton dissociation) of photons are calculated based on modern parametrizations of deep inelastic structure functions in a broad range of $x$ and $Q^2$. We focus on processes with single and double proton dissociation. Highly excited remnant systems hadronise producing particles that can be vetoed in the calorimeter. We calculate associated gap survival factors. The gap survival factors depend on the process, mass of the remnant system and collision energy. The rapidity gap survival factor due to remnant fragmentation for double dissociative (DD) collisions is smaller than that for single dissociative (SD) process. We observe approximate factorisation: $S_{R,DD} \approx S_{R,SD}^2$ when imposing rapidity veto. For the $W^+W^-$ final state, the remnant fragmentation leads to a taming of the cross section when the rapidity gap requirement is imposed. Also for $t \bar t$ quark-antiquark pairs such a condition reverses the hierarchy observed for the case when such condition is taken into account. Our results imply that for the production of such heavy objects as $t$ quark and $\bar t$ antiquark the virtuality of the photons attached to the dissociative system are very large ($Q^2 <$ 10$^{4}$ GeV$^2$). A similar effect is observed for the $W^+ W^-$ system.
