ITP |
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Teilchentee SS 2019
Seminar at the Institute for Theoretical Physics, Heidelberg University
on Thursdays, 4 pm
organizers: Juergen Berges and Joerg Jaeckel
Before each seminar, the speaker gives an informal Pre-Talk, introducing the MSc and PhD students at the ITP to the broader context of the topic of the seminar.
Pre-Talks start at 3:30 pm
Date: 16.5.2019
Speaker: Matthias Neubert
Title: Effective Field Theory after a New-Physics Discovery
Abstract
When a new heavy particle is discovered at the LHC or at a future high-energy collider, it will be interesting to study its decays into Standard Model particles using an effective field-theory framework. We point out that the proper effective theory must be based on non-local operators defined in soft-collinear effective theory (SCET). For the interesting case where the new resonance is a gauge-singlet spin-0 boson, which is the first member of a new sector governed by a mass scale $M$, we show how a consistent scale separation between $M$ and the electroweak scale $v$ is achieved up to next-to-next-to-leading order in the expansion parameter $\lambda\sim v/M$. The Wilson coefficients in the effective Lagrangian depend in a non-trivial way on the mass of the new resonance and the masses of yet undiscovered heavy particles. Large logarithms of the ratio $M/v$ can be systematically resummed using the renormalization group. We develop a SCET toolbox, with which it is straightforward to construct the relevant effective Lagrangians for new heavy particles with other charges and spin.
