PIRSA:25030169

Running EFT-hedron with null constraints at loop level

(2025). Running EFT-hedron with null constraints at loop level. Perimeter Institute. https://pirsa.org/25030169

Running EFT-hedron with null constraints at loop level. Perimeter Institute, Mar. 18, 2025, https://pirsa.org/25030169 

          @misc{ pirsa_PIRSA:25030169,
            doi = {10.48660/25030169},
            url = {https://pirsa.org/25030169},
            author = {},
            keywords = {Particle Physics},
            language = {en},
            title = {Running EFT-hedron with null constraints at loop level},
            publisher = {Perimeter Institute},
            year = {2025},
            month = {mar},
            note = {PIRSA:25030169 see, \url{https://pirsa.org}}
          }
Long-Qi Shao
Talk numberPIRSA:25030169
DOI10.48660/25030169
Collection
Talk Type Scientific Series
Subject

Abstract

I will introduce how to incorporate loop contributions into positivity bounds in a massless scalar theory with shift symmetry. The allowed region of Wilson coefficients is called the EFT-hedron. With loop contributions, the n=4 null constraint, which plays an important role in determining the allowed region for g3–g4 (the Wilson coefficients of dimension-10 and dimension-12 operators, respectively), is modified. This modification of the null constraint reveals new features of the EFT-hedron. We obtained a much stronger bound for g2 (the Wilson coefficient of dimension-8 operators) without using the full unitarity condition. Furthermore, we found a negative g4, which is not possible under the tree-level bound. It would be interesting to generalize our method to more complicated theory and test our results.