Events List

DateEvent TypeSpeaker
01/01/2026Holiday [ + ]
01/02/2026Holiday [ + ]
01/14/2026Special SeminarSilvia Almada Monter [ + ]
01/14/2026Informal HEP TalkSam Witte [ + ]
01/19/2026Holiday [ + ]
01/20/2026First Day of Class [ + ]
01/20/2026Astro SeminarWolfgang Kerzendorf [ + ]
01/20/2026Cosmic Happy HourMarius Kongsore [ + ]
01/21/2026HEP SeminarUri Kol [ + ]
01/22/2026Physics Dept ColloquiumKaden Hazzard [ + ]
01/26/2026Reseach GroupAndrew MacFadyen [ + ]
01/27/2026Astro SeminarJeff Hazboun [ + ]
01/28/2026HEP Seminar [ + ]
01/28/2026HEP SeminarCarolina Figueiredo [ -- ]

Title: Large n: scattering amplitudes at large multiplicity
Abstract: What happens when we scatter a large number $n$ of particles, say with $n = 10^1000$? This question is out of reach of all existing approaches to scattering amplitudes, whether directly through Feynman diagrams or recursion relations. In this talk, I will study this problem at tree-level for a simple scalar theory, Tr($phi^3$) theory, and describe a new way of accessing this regime. Remarkably, we find that at large $n$ the sum over diagrams "smooths out". Working at leading order in $n$, and in certain "positive" regions of kinematic space, the final answer is astonishingly simple, given by a single term, determined by an optimization problem associated with a biased random walk. I will also describe a new "dual" theory for amplitudes, which in simple limits reduces to the motion of a particle on a half-line, evolving for a "time'' $n$, allowing us to systematically extract the $1/n$ expansion of the amplitude. I will end by explaining how these results generalize to other large $n$ contexts, from the scattering of pions, to string scattering at ultra-high energies. (2:00 PM - 3:00 PM, 726 Broadway, 940, CCPP Seminar)
01/29/2026Physics Dept ColloquiumKen Dill [ + ]
02/02/2026Reseach GroupAndrew MacFadyen [ + ]
02/03/2026Astro SeminarMax Isi [ + ]
02/04/2026HEP Seminar [ + ]
02/04/2026HEP SeminarBeatrix Muehlmann [ + ]
02/09/2026Reseach GroupAndrew MacFadyen [ + ]
02/10/2026Special SeminarShai Chester [ + ]
02/10/2026Astro SeminarNicholas Rui [ + ]
02/12/2026Oral DefenseMarius Kongsore [ + ]
02/16/2026Holiday [ + ]
02/16/2026Reseach GroupAndrew MacFadyen [ + ]
02/18/2026HEP SeminarAlice Garoffolo [ + ]
02/23/2026Reseach GroupAndrew MacFadyen [ + ]
02/25/2026HEP SeminarSahand Seifnashri [ + ]
02/26/2026Physics Dept ColloquiumNatasha Holmes [ + ]
03/02/2026Reseach GroupAndrew MacFadyen [ + ]
03/03/2026Astro SeminarNadine Soliman [ + ]
03/04/2026HEP SeminarRegina Caputo [ + ]
03/09/2026Reseach GroupAndrew MacFadyen [ + ]
03/10/2026Astro SeminarNeal Dalal [ + ]
03/11/2026HEP SeminarJiji Fan [ + ]
03/12/2026Physics Dept ColloquiumVictor M Yakovenko [ + ]
03/16/2026Spring Break [ + ]
03/16/2026Reseach GroupAndrew MacFadyen [ + ]
03/17/2026Spring Break [ + ]
03/18/2026Spring Break [ + ]
03/19/2026Spring Break [ + ]
03/20/2026Spring Break [ + ]
03/23/2026Reseach GroupAndrew MacFadyen [ + ]
03/24/2026Astro SeminarYanqin Wu [ + ]
03/30/2026CCPP Brown BagGabriel Cuomo [ + ]
03/30/2026Reseach GroupAndrew MacFadyen [ + ]
03/31/2026Astro SeminarNicolas Fernandez Gonzalez [ + ]
04/01/2026HEP SeminarKevin Langhoff [ + ]
04/06/2026Reseach GroupAndrew MacFadyen [ + ]
04/07/2026Astro SeminarAnna-Christina Eilers [ + ]
04/08/2026HEP SeminarSilviu Pufu [ + ]
04/13/2026Reseach GroupAndrew MacFadyen [ + ]
04/14/2026Astro SeminarAndrei M. Beloborodov [ + ]
04/15/2026HEP SeminarAlfredo Guevara [ + ]
04/20/2026Reseach GroupAndrew MacFadyen [ + ]
04/21/2026Astro SeminarCharlie Conroy [ + ]
04/22/2026HEP SeminarJan Albert [ + ]
04/27/2026Reseach GroupAndrew MacFadyen [ + ]
04/28/2026Astro SeminarKelsey Lund [ + ]
04/29/2026HEP SeminarHuangyu Xiao [ + ]
05/04/2026Reseach GroupAndrew MacFadyen [ + ]
05/06/2026HEP SeminarCiaran Williams [ + ]
05/11/2026Special SeminarKleban [ + ]