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SUMMARY:Gauge Theory Bootstrap: computing pion amplitudes and low energy p
 arameters from QCD - Yifei He\, Ecole Normale Supérieure
DTSTART:20250320T130000Z
DTEND:20250320T140000Z
UID:TALK225292@talks.cam.ac.uk
CONTACT:122734
DESCRIPTION:We propose the Gauge Theory Bootstrap -- a method to compute t
 he pion S-matrix that describes the low energy physics of the strong inter
 action and other similar gauge theories. Using this method\, we compute pi
 on scattering phase shifts for all partial waves with angular momentum \\e
 ll<=3 up to 2 GeV and calculate the low energy chiPT coefficients L_{1\,2\
 ,4\,6}​. The method looks for the most general S-matrix that matches at 
 low energy the tree level amplitudes of the non-linear sigma model and at 
 high energy\, QCD sum rules and form factors. This is a theoretical/numeri
 cal calculation that uses as only data the pion mass m_\\pi​\, pion deca
 y constant f_\\pi​ and the QCD parameters N_c​=3\, N_f​=2\, m_q​ a
 nd alpha_s​. All results are in reasonable agreement with experiment. In
  particular\, we find the rho(770)\, f_2​(1270) and rho(1450) resonances
 . The interplay between the UV gauge theory and chiral dynamics is an exam
 ple of a general situation where we know the microscopic theory as well as
  the effective theory of long wavelength fluctuations but we want to solve
  the strongly coupled dynamics at intermediate energies. The bootstrap bui
 lds a bridge between the low and high energy by determining the consistent
  S-matrix that matches both and provides\, in this case\, a new direction 
 to understand the strongly coupled physics of gauge theories.\n\nReference
 s:\n[1] YH and Martin Kruczenski\, Phys. Rev. Lett. 133\, 191601 and Phys.
  Rev. D 110\, 096001.\n[2] YH and Martin Kruczenski\, arXiv: 2403.10772.
LOCATION:Potter Room (B1.19)
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