Theory Seminar(Prof. Yu-tin Huang)

Start2018/12/03(Mon) 2:00 PM
End2018/12/03(Mon) 3:00 PM
VenueKenkyu Honkan 1F, Meeting Room 1
TitleBuild the wall and drain the swamp: positive constraints on EFT from the UV
SpeakerProf. Yu-tin Huang (Department of Physics, National Taiwan University)
ContactYusuke Kimura/


In this talk I will introduce new constraints on couplings of operators in

effective field theory derived from Unitarity and Lorentz invariance in the

UV. These constraints come in the form of positive geometries in the space

of couplings. The origin of this positivity originates from the remarkable

positive properties of Gegenbauer polynomials, which are the basis

polynomials dictated by Lorentz invariance. Unitarity then dictates that

the discontinuity of the S-matrix has a positive expansion on these

polynomials. This double positivity give rises to the mathematical object

that we named the "EFThedron", for which all consistent QFT must reside in.

Adding that the underlying theory has a worldsheet description, allows us

to begin to carve out the string landscape in an on-shell fashion.