Joint Particle Physics Meeting - "The electroweak effective field theory from on-shell amplitudes" / "Changing the Universe During the Dark Ages with New Physics"

by Gauthier Durieux / Hongwan Liu

Technion / New York University & Princeton

at Special seminar

Wed, 06 Nov 2019, 10:55
Barkan Hall (adjacent to the Student Center)

Abstract

10:55 Refreshments

11:10 Gauthier Durieux (Technion)
"The electroweak effective field theory from on-shell amplitudes"
Abstract: On-shell methods trivialize the representation of particles to provide an efficient description of scatterings without gauge or field redefinition redundancies. Applications to effective field theories (EFTs) have recently multiplied, yielding new understandings (e.g. of non-renormalizations) and simpler descriptions (e.g. for operator enumerations). The treatment of massive spinors introduced by Arkani-Hamed, Huang and Huang now notably allows for a systematic description of the electroweak sector of the standard-model effective field theory. We aimed at putting this program on firm grounds. After an introduction to the massless and massive spinor formalisms, I will describe how we bootstrapped all three-point amplitudes of the electroweak EFT, from its particle spectrum, Poincaré symmetry and locality only. We explicitly examined the bottom-up emergence of the electroweak symmetry from perturbative unitarity. A full example of four-point amplitude was worked out, including both factorizable and contact-term contributions. The matching between amplitude and operator coefficients was finally performed and paves the way for electroweak-EFT computations with on-shell methods. [1909.10551]

12:10  Lunch

13:00  Hongwan Liu (NYU & Princeton)
"Changing the Universe During the Dark Ages with New Physics"
Abstract: The injection or removal of energy can change the properties of the baryon fluid between recombination and reionization, and can leave observable changes in the ionization and thermal histories of the universe; it can also generate spectral distortions that may be detectable in the CMB today. In this talk, I will detail some recent and significant improvements in calculating these effects, and discuss why we should be excited about these signatures, especially in the context of dark matter.

Created on 01-11-2019 by Kats, Yevgeny (katsye)
Updaded on 01-11-2019 by Kats, Yevgeny (katsye)