报告人：李政阳助理研究员（四川大学）

题目：Quantum field theory with two-fold Wigner degeneracy

时间：2023年11月19日（周日）下午15:00

地点：理工楼1226

邀请人：张玉鹏

报告摘要：In 1964, Weinberg derived the Dirac equation and its higher-spin generalizations from the irreducible unitary representations of the Poincarè group. Due to the first-principle derivation given by Weinberg, and the subsequent successes of the Standard Model of particle physics, it is commonly believed that all massive spin-half quantum fields must satisfy the Dirac equation.

The theory of spin-half mass dimension one field presents a shift to the prevailing consensus. These quantum fields have the following properties. They satisfy the Klein-Gordon but not the Dirac equation and have mass dimension one instead of three-half. Here, we present the construction of mass dimension one fields and explain why the theory is not in conflict with Weinberg's derivation. We show that the mass dimension one fields furnish the irreducible representation of the extended Poincarè group where the particle-antiparticle degrees of freedom is doubled from four to eight. The doubling of degrees of freedom (two-fold degeneracy) resolves the long-standing problems of rotational symmetry violation and non-locality. Particle states with such degeneracies was originally envisioned by Wigner (hence the term Wigner degeneracy). The introduction of Wigner degeneracy allows us to evade Weinberg's derivation and construct massive spin-half fields that are local, have mass dimension one, and respect Lorentz symmetry. Since the fields have mass dimension one, they have renormalizable quartic self-interaction and cannot form multiplets with the Standard fermions. These properties makes them viable dark matter candidates.

报告人简介：李政阳，四川大学理论物理中心助理研究员。2012年在Dharam Vir Ahluwalia的指导下在特伯雷大学获得博士学位。之后在巴西和印度从事博士后研究。2019年起入职四川大学。主要研究领域是粒子物理学和量子场论。