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SUMMARY:Chiral and $U(1)_A$ symmetries in background magnetic fields from 
 lattice QCD
DTSTART;VALUE=DATE-TIME:20261010T093000Z
DTEND;VALUE=DATE-TIME:20261010T094500Z
DTSTAMP;VALUE=DATE-TIME:20261005T030045Z
UID:indico-contribution-2820@indico.itp.ac.cn
DESCRIPTION:Speakers: 丹 张 (Central China Normal University)\nUnderstan
 ding how external magnetic fields affect chiral and singlet $U(1)_A$ symme
 try breaking is an important question in QCD under extreme conditions. In 
 a pure magnetic background\, the unequal electric charges of the light qua
 rks explicitly reduce the non-singlet flavor symmetry\, making it necessar
 y to identify the appropriate neutral mesonic partner channels. We clarify
  the neutral-sector symmetry structure and identify $\\chi_{\\pi^0}-\\chi_
 \\sigma$ as the chiral-partner splitting associated with the surviving neu
 tral non-singlet axial symmetry\, and $\\chi_{\\pi^0}-\\chi_{\\delta^0}$ a
 s the singlet $U(1)_A$ partner splitting.\nUsing fixed-scale $(2+1)$-flavo
 r HISQ ensembles with $m_\\pi\\simeq220\\\,\\mathrm{MeV}$ at vanishing mag
 netic field\, we study these observables over a broad range of temperature
 s and magnetic fields. At low temperatures\, both splittings increase with
  $eB$. At intermediate temperatures\, both splittings decrease with increa
 sing $eB$ once the field is sufficiently strong. The decrease of the singl
 et $U(1)_A$ partner splitting sets in at larger $eB$ and is milder than in
  the chiral channel. These results provide fixed-scale lattice-QCD evidenc
 e for distinct magnetic responses of the neutral chiral and singlet $U(1)_
 A$ partner susceptibility splittings.\n\nhttps://indico.itp.ac.cn/event/43
 7/contributions/2820/
LOCATION:会议楼2 CXII102
URL:https://indico.itp.ac.cn/event/437/contributions/2820/
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