Harland-Lang L A, Khoze V A, Ryskin M G
1Clarendon Laboratory, Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Parks Road, Oxford, OX1 3PU UK.
2Institute for Particle Physics Phenomenology, University of Durham, Durham, DH1 3LE UK.
Eur Phys J C Part Fields. 2019;79(1):39. doi: 10.1140/epjc/s10052-018-6530-5. Epub 2019 Jan 18.
We present results of the updated SuperChic 3 Monte Carlo event generator for central exclusive production. This extends the previous treatment of proton-proton collisions to include heavy ion (pA and AA) beams, for both photon and QCD-initiated production, the first time such a unified treatment of exclusive processes has been presented in a single generator. To achieve this we have developed a theory of the gap survival factor in heavy ion collisions, which allows us to derive some straightforward results about the scaling of the corresponding cross sections. We compare against the recent ATLAS and CMS measurements of light-by-light scattering at the LHC, in lead-lead collisions. We find that the background from QCD-initiated production is expected to be very small, in contrast to some earlier estimates. We also present results from new photon-initiated processes that can now be generated, namely the production of axion-like particles, monopole pairs and monopolium, top quark pair production, and the inclusion of loops in light-by-light scattering.
我们展示了用于中心独产过程的升级版SuperChic 3蒙特卡罗事件发生器的结果。这将质子 - 质子碰撞的先前处理扩展到包括重离子（pA和AA）束，用于光子和QCD引发的产生过程，这是首次在单个发生器中对独产过程进行这样的统一处理。为实现这一点，我们发展了重离子碰撞中的能隙存活因子理论，这使我们能够得出一些关于相应截面标度的直接结果。我们将其与大型强子对撞机（LHC）铅 - 铅碰撞中近期ATLAS和CMS对光 - 光散射的测量结果进行比较。我们发现，与一些早期估计相反，QCD引发产生过程的背景预计非常小。我们还展示了现在可以生成的新光子引发过程的结果，即类轴子粒子、单极子对和单极偶素的产生、顶夸克对产生，以及在光 - 光散射中包含圈图。
