* FíSICA NUCLEAR * Seminario de los martes

Hola a Todos,

les copio info del seminario de mañana.

saludos

Rolo

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Dear Colleagues,

 

Please join us for our next Rising Researchers seminar tomorrow (February 6th) at 10:30 AM Pacific Time by Damiano Fiorillo --- Niels Bohr Institute.

 

The seminar is fully virtual. Please find the Zoom link below.

 

Title: Supernova neutrinos as a fluid: The subtleties of large neutrino secret interactions

 

Abstract: 

Large neutrino secret interactions are not excluded and could be a portal to hitherto unknown physics beyond the standard model. The consequence of supernova (SN) neutrinos forming a self-coupled relativistic fluid has been a long-standing unresolved mystery that has been recently revived. For the first time, we solve all steps, systematically using relativistic hydrodynamics, and a simplified source model.  First, we examine how heat transport via neutrino diffusion inside the central protoneutron star (PNS) is affected by the secret interactions. We solve the equations of the relativistic fluid coupled to the nuclear matter in the presence of temperature gradients, showing that the heat flux transported by the neutrino fluid is very similar to the non-interacting case. Small energy-transfer modifications may affect the neutrino-driven explosion mechanism, but on present evidence are not ruled in or out. If secret interactions violate lepton number, the PNS would quickly deleptonize, although even in this case no definite statement on the SN fate can be drawn without dedicated simulations.  Later, we discuss the emission of the neutrino fluid from the PNS surface, which we simplify as an ideal blackbody. While the standard blackbody emission of non-interacting particles is described by the Stefan-Boltzmann law, we show that the fluid nature of the emitted neutrinos changes the effective temperature outside the blackbody, with the fluid being emitted sonically from the PNS surface. The energy outflow is remarkably similar to the standard case.  Finally, after the neutrino fluid leaves the PNS, we study its free expansion, showing that it evolves into a fireball, while its spectrum in the laboratory frame remains unaffected. After the density has rarefied sufficiently, secret interactions decouple, leading to the formation of the neutrino spectrum observable at Earth.  Overall, the impact on SN physics and the neutrino signal is remarkably small. Signal duration is left unchanged; even for complete thermalization within the fireball, the observable spectrum barely changes. The results of this work are published in two preprints, one of which is accepted and the other of which is presently under review.

 

Zoom link:

https://us06web.zoom.us/j/85077701870

 

Sincerely,

Rising Researchers Seminar Series Committee

 

Upcoming seminar:

Feb 20th:  "Quantum Monte Carlo Calculations of neutron scattering from alpha" by Abraham Flores