BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Andreas Mantziris (Imperial College) DTSTART:20210408T140000Z DTEND:20210408T150000Z DTSTAMP:20260423T003256Z UID:IFTWeb/43 DESCRIPTION:Title: Cosmological implications of electroweak vacuum instability: constraints o n the Higgs curvature coupling from inflation\nby Andreas Mantziris (I mperial College) as part of IFT-Madrid Webinars\n\n\nAbstract\nThe current experimentally measured parameters of the Standard Model (SM) suggest tha t our universe lies in a metastable electroweak vacuum\, where the Higgs f ield could decay to a lower vacuum state with catastrophic consequences. O ur measurements dictate that such an event has not happened yet\, despite the many different mechanisms that could have triggered it during our past light-cone. Via this observation\, we can establish a promising link betw een cosmology and particle physics and thus constrain important parameters of our theories. The focus of our work has been to explore this possibili ty by calculating the probability of the false vacuum to decay during the period of inflation and using it to constrain the last unknown renormalisa ble SM parameter $\\xi$\, which couples the Higgs field with space-time cu rvature. In our latest study\, we derived lower bounds for the Higgs-curva ture coupling from vacuum stability in three inflationary models: quadrati c and quartic chaotic inflation\, and Starobinsky-like power-law inflation . In contrast to most previous studies we took the time-dependence of the Hubble rate into account both in the geometry of our past light-cone and i n the Higgs effective potential\, which is approximated with three-loop re normalisation group improvement supplemented with one-loop curvature corre ctions. We find that in all three models\, the lower bound is $\\xi \\gtrs im 0.051 ... 0.066$ depending on the top quark mass. We also demonstrated that vacuum decay is most likely to happen a few e-foldings before the end of inflation.\n LOCATION:https://researchseminars.org/talk/IFTWeb/43/ END:VEVENT END:VCALENDAR