July 21 2026 (in-person)

Volodymyr Y. Vovchenko ( University of Houston)

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

[Slide]  [Youtube]

Title: Extracting baryon number susceptibilities at finite density from heavy-ion collisions

Abstract:  Exploring the QCD phase diagram at finite baryon density and searching for the QCD critical point remain major goals of nuclear physics. I will first discuss recent constraints obtained from the constant entropy contours method, recently extended to a four-dimensional thermodynamic parameter space. These results place the candidate critical region near the chemical freeze-out in intermediate-energy heavy-ion collisions.

I will then present an extended hydrodynamic framework for describing proton-number cumulants in heavy-ion collisions. Augmented with a maximum-entropy freeze-out prescription and a generalized subensemble acceptance method, the framework relates experimentally measured proton cumulants to equilibrium baryon-number susceptibilities while consistently incorporating the equation of state, kinematic acceptance, and global baryon number conservation.

A Bayesian analysis of experimental fluctuation measurements then enables the direct extraction of baryon-number susceptibilities from heavy-ion collision data. I will discuss the inferred susceptibilities in comparison with a lattice-QCD-based equation of state and examine their implications for the possible existence and location of the QCD critical point.

[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.