Apr. 28, 2026 (In person)

Prof.  Marcus Bluhm (SUBATECH, Nantes and University of Wrocław)

Location: Swiatecki Lounge B70 annex - 228

Time: 4:00pm Pacific Time

ZOOM for those who are unable to come in-person: LINK

Host: Volker Koch

Title: Dynamics of (coupled) charge fluctuations in heavy-ion collisions 

Abstract: Fluctuation observables measured in heavy-ion collisions provide a means to explore and delineate the phase diagram of strongly interacting matter. The search for the expected QCD chiral critical point, for example, is one of the major goals in current and future heavy-ion programs. To understand these measurements, theoretical approaches base on the assumption of local thermal equilibrium and, moreover, on chemical equilibration when the particle multiplicities are fixed. The matter created in heavy-ion collisions is, however, spatially tiny, evolves highly dynamically, is extremely short-lived, and inhomogeneous even near a critical point. In this talk, the dynamics of the fluctuations in conserved charges (such as the net-baryon number) and correlation functions is discussed from different angles, including the competition between diffusion and expansion, critical slowing down near the critical point, finite system-size effects as well as the coupling between different conserved charges. It is shown, for example, that by using realistic diffusion rates for the late hadronic stage of a heavy-ion collision, it is difficult to maintain local thermal equilibrium. 

[postponed]

Prof. Jen-Chieh Peng  (University of Illinois at Urbana-Champaign)

Location: Swiatecki Lounge B70 annex - 228

Time: 4:00pm Pacific Time

ZOOM for those who are unable to come in-person: LINK

Host: Keh-Fei Liu

Title: Evolution of Helicity Property of Relic Neutrinos and Implications 

on Their Detection

Abstract: Neutrinos in the early Universe decoupled essentially in helicity eigenstates.

As they propagate through the Universe, their helicities could be modified via

two effects. First, neutrinos with a finite magnetic moment would rotate their

spins with respect to their momenta as they encounter cosmic magnetic fields,

modifying their helicities. Second, the bending of neutrino's spin by a

gravitational field lags the bending of its momentum, again modifying its helicity. 

We study both effects and investigate the implications of the

helicity modification on the detection of relic neutrinos using the Inverse

Tritium Beta Decay (ITBD) reaction. We find that the ITBD rate depends

sensitively on the neutrino mass hierarchy and on the Dirac or Majorana nature

of the neutrinos. This talk is based on several papers in collaboration with 

Gordon Baym.