This paper is a write-up of the ideas that were presented, developed and discussed at the third International Workshop on QCD Challenges from pp to A–A, which took place in August 2019 in Lund, Sweden (Workshop link: https://indico.lucas.lu.se/event/1214/). The goal of the workshop was to focus on some of the open questions in the field and try to come up with concrete suggestions for how to make progress on both the experimental and theoretical sides. The paper gives a brief introduction to each topic and then summarizes the primary results.

中文翻译：

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从pp碰撞到A–A碰撞的QCD挑战

本文是在2019年8月在瑞典隆德举行的第三届从pp到A–A的QCD挑战国际研讨会上介绍，发展和讨论的想法的文章（工作坊链接：https：// indico.lucas.lu.se/event/1214/）。研讨会的目的是集中于该领域的一些未解决的问题，并试图就如何在实验和理论两方面取得进展提出具体建议。本文简要介绍了每个主题，然后总结了主要结果。