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\nIn the first part of the talk\, we will ask a bedrock question of quantum gra vity: Is string theory unique? String amplitudes famously accomplish s everal extraordinary and interrelated mathematical feats\, including a n infinite spin tower\, tame UV behavior\, and dual resonance. I will demonstrate that it is possible to construct infinite new classes of t ree-level\, dual resonant amplitudes with customizable\, nonlinear mas s spectra. The construction generalizes naturally to n-point scatterin g and allows for a worldsheet integral representation. However\, these constructions can be strongly constrained using multiparticle factori zation\, which provides a powerful new set of tools for building consi stent amplitudes. In the case of a Regge spectrum\, I will investigate whether string amplitudes can be bootstrapped from first principles\, finding extra freedom in the dynamics that allows for a new class of dual resonant hypergeometric amplitudes.

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\nIn the second part of the talk\, I will take a particle physics-driven approach\, constr aining effective field theories using unitarity and causality. We will construct analytic dispersion relations for the effective field theor y of the standard model\, bounding the size and sign of higher-dimensi on operators\, with significant implications for CP and flavor violati on. These positivity bounds allow us to connect qualitatively differen t experiments\, including predictions for the LHC and precision measur ements. I will then apply these tools in a cosmological context\, buil ding positivity bounds for the theory of multifield inflation and extr acting predictions for non-Gaussianities in the cosmic microwave backg round.

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\nTaken together\, these two complementary initiative s comprise a program unifying phenomenological\, formal\, and cosmolog ical approaches to high energy physics\, bringing together powerful to ols bridging fields to map the possibilities of future physics. URL:https://www.physics.wisc.edu/events/?id=8582 END:VEVENT END:VCALENDAR