The S-matrix program of the nineteen-sixties was founded on the belief that scattering amplitudes should be uniquely determined by a small set of mathematical and physical principles. While this dream has yet to be realized, significant progress has recently been made towards understanding the universal properties of scattering amplitudes, and teasing out the concrete implications of principles such as causality and unitarity. In large part, this progress has been achieved by two separate communities investigating the S-matrix in different regimes---one working perturbatively to bootstrap the explicit functional form of scattering amplitudes at weak coupling, and the other working to bootstrap the space of possible amplitudes non-perturbatively. This workshop aims to bring these communities together, in order to highlight promising points of contact and promote new collaboration. Specific topics to be discussed include:
 

• analytic and numerical bootstrap methods
• constraints from crossing, unitarity, and causality
• all-order perturbative results
• resummation and resurgence
• perturbative and non-perturbative symmetries
• Landau analysis
• special functions

 
Organizers: Lucia Cordova (CERN), Lance Dixon (SLAC), Andrew McLeod (University of Edinburgh), Alexander Zhiboedov (CERN)