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DTSTAMP:20260926T103412Z
UID:55d93ba2-07cf-4c9e-a540-5e082fe2ac99
DTSTART:20260929T141500
DTEND:20260929T154500
DESCRIPTION:Lorentz invariance is the cornerstone of modern physics. Howeve
 r\, many ‘real-world’ systems from condensed matter to cosmology have 
 a preferred background which spontaneously breaks Lorentz invariance\, con
 sequently yielding Goldstone bosons. In this talk\, we will show that the 
 notion of microcausality survives the symmetry breaking\, implying analyti
 city of the retarded two-point function. Using that\, we show that dispers
 ion relations of non-dissipative Goldstone modes can be written in terms o
 f ‘typically-real functions’\, yielding two-sided bounds on Wilson coe
 fficients of higher-derivative operators as explicit functions of the soun
 d speed. We check these bounds against multiple systems such as the U(1) s
 uperfluid and QED. Finally\, I will comment on the implications for cosmol
 ogy through the EFT of Inflation and Dark Energy.
LOCATION:ETH Zürich\, Hönggerberg HIT F 12
ORGANIZER:Warin Patrick McBlain
SUMMARY:Microcausality Bounds on Goldstone Dispersion Relations
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