Event calendar file
Free Meson Seminars
Probing the relaxed relaxion across frontiers
by Prof. Gilad Perez (Weizmann Institute)
Thursday, July 16, 2020
from
to
(Asia/Kolkata)
at Zoom
at Zoom
| Description |
Please contact rishi(at)theory(dot)tifr(dot)res(dot)in for the zoom meeting id and the password for this seminar. Cosmological relaxation of the electroweak scale is an attractive scenario addressing the gauge hierarchy problem. Its main actor, the relaxion, is a light spin-zero field which dynamically relaxes the Higgs mass with respect to its natural large value. We show that the relaxion is generically stabilized at a special position in the field space, which leads to suppression of its mass and potentially unnatural values for the model's effective low-energy couplings. In particular, we find that the relaxion mixing with the Higgs can be several orders of magnitude above its naive naturalness bound. Low energy observers may thus find the relaxion theory being fine-tuned although the relaxion scenario itself is constructed in a technically natural way. More generally, we identify the lower and upper bounds on the mixing angle. We examine the experimental implications of the above observations at the energy, luminosity and precision frontiers. In addition, we study the recent XENON1T excess in context of solar scalar. We show that m_ϕ~2 keV sinθ=10(−8) can explain the excess. The best fit parameters are in tension with stellar cooling bounds. We furthermore point that the shallow potential of the relaxion implies that the large densities of red giants could naturally destabilise its potential similar to chameleon-type models, potentially suppressing the stellar cooling, albeit for masses of the order of 200 eV or less. This scenario is being currently tested using the S2-only analysis at XENON1T. https://www.youtube.com/watch?v=IUijSEUBPKg |
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