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(Seminar)The strong CP problem revisited

08/14 2020
  • Title (Seminar)The strong CP problem revisited
  • Speaker
  • Date
  • Venue
  • Abstract

    CAS Key Laboratory of Theoretical Physics

    Institute of Theoretical Physics

    Chinese Academy of Sciences

    Seminar

    Title

    题目

    The strong CP problem revisited

    Speaker

    报告人

    艾稳元  博士

    Affiliation

    所在单位

    比利时天主教鲁汶大学

    Date

    日期

    2020年8月14日(周五)下午15:00

    Venue

    地点

    腾讯会议 会议 ID:581 297 6941

    Contact Person

    所内联系人

    郭奉坤

    Abstract

    摘要

    The strong CP problem, i.e., the question why the CP violation by the strong interaction is smaller than 10^-10, is one of the most important problems in the Standard Model. There are two potential sources of CP violation in QCD, namely complex chiral phases in the quark mass matrix and the so-called 't Hooft vertex, which arises from instanton effects. Only one of them can be removed by field redefinitions, meaning that QCD should violate CP unless the chiral phases in these two terms happen to be aligned. In this talk, I will discuss a recent computation of the fermionic correlation functions in the θ vacuum in which we find such an alignment. If our approach is correct the phases can be removed by chiral rotations of quarks, and thus there is no physical CP violation in QCD.