Hadron Ion Tea (HIT) Seminar Series
[formerly the Heavy Ion Tea Seminars]
Nuclear Science Division
Lawrence Berkeley National Laboratory
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HIT seminars are on Tuesdays at 4:00pm Pacific Time (unless otherwise noted)
HIT seminars are on Tuesdays at 4:00pm Pacific Time (unless otherwise noted)
Organizers: Yuxun Guo, Yuuka Kanakubo, Felipe Ortega, Mateusz Ploskon, Bigeng Wang and Zhenyu Ye (Contact us at hit-organizers@lbl.gov)
Previous seminars can be viewed on our HIT Youtube Channel
Upcoming seminars
Upcoming seminars
Welcome to our Hadron-Ion Tea Seminar Series in 2025! All talks are available on zoom, some are in-person as well - we hope you join us!
Dec. 09, 2025 (Remote)
Jonathan D. Kroth (Iowa State U.)
Location: Room 328, Birge Hall, UC Berkeley Campus MAP
Time: 4:00pm Pacific Time
ZOOM for those who are unable to come in-person: LINK
Host: Feng Yuan
Title: Searching for missing direct photons in heavy-ion collisions with P and CP violation
Abstract: The spectrum of direct photons from the quark-gluon plasma produced at RHIC has defied the efforts of theorists to describe it. In particular, a significant increase in the number of photons produced at low $p_T$ and the correct non-zero $v_2$ flow coefficient have yet to be predicted simultaneously. In an attempt to investigate possible solutions, we study synchrotron radiation from massive fermions in a medium with a chiral chemical potential and a chiral gradient parallel to the magnetic field. In the limit of a non-interacting plasma, these parameters increase the number of photons produced at low $p_T$ while suppressing the traditionally large synchrotron radiation flow coefficient $v_2$ to levels comparable to those seen in experiments. Given these results, we suggest that P- or CP-violating domains, long conjectured to exist in quark-gluon plasma and recently suggested by results from the STAR collaboration, may be a solution to the problem of missing direct photons.
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