Measurements of the chiral magnetic effect with background isolation in 200 GeV Au+Au collisions at STAR

Zhao, Jie

doi:10.1016/j.nuclphysa.2018.08.035

Title: Measurements of the chiral magnetic effect with background isolation in 200 GeV Au+Au collisions at STAR

Abstract

Using two novel methods, pair invariant mass (m_inv) and comparative measurements with respect to reaction plane (Ψ_RP) and participant plane (Ψ_PP), we isolate the possible chiral magnetic effect (CME) from backgrounds in 200 GeV Au+Au collisions at STAR. The invariant mass method identifies the resonance background contributions, coupled with the elliptic flow (ν₂), to the charge correlator CME observable (Δγ). At high mass (m_inv > 1.5 GeV/c²) where resonance contribution is small, we obtain the average Δγ magnitude. In the low mass region (m_inv > 1.5 GeV/c²), resonance peaks are observed in Δγ(m_inv). An event shape engineering (ESE) method is used to model the background shape in m_inv to extract the potential CME signal at low m_inv. In the comparative method, the Ψ_RP is assessed by spectator neutrons measured by the ZDCs, and the Ψ_PP by the 2^nd-harmonic event plane measured by the TPC. The ν₂ is stronger along Ψ_PP and weaker along Ψ_RP; in contrast, the magnetic field, mainly from spectator protons, is weaker along Ψ_PP and stronger along Ψ_RP. As a result, the Δγ measured with respect to Ψ_RP and Ψ_PP contain different amounts of CME and background, and can thus determine these two contributions. It is foundmore »« less

Authors:

^[1]

Purdue Univ., West Lafayette, IN (United States)

Publication Date:: Tue Jan 22 00:00:00 EST 2019

Research Org.:: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Nuclear Physics (NP)

Contributing Org.:: STAR Collaboration

OSTI Identifier:: 1580374

Grant/Contract Number:: AC02-05CH11231; SC0012910

Resource Type:: Accepted Manuscript

Journal Name:: Nuclear Physics. A

Additional Journal Information:: Journal Volume: 982; Journal Issue: C; Journal ID: ISSN 0375-9474

Publisher:: Elsevier

Country of Publication:: United States

Language:: English

Subject:: 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; QCD; heavy-ion collisions; chiral magnetic effect; invariant mass; reaction plane; participant plane

Citation Formats


                    Zhao, Jie. Measurements of the chiral magnetic effect with background isolation in 200 GeV Au+Au collisions at STAR.  United States: N. p., 2019. 
Web.  doi:10.1016/j.nuclphysa.2018.08.035.

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                    Zhao, Jie. Measurements of the chiral magnetic effect with background isolation in 200 GeV Au+Au collisions at STAR.  United States.  https://doi.org/10.1016/j.nuclphysa.2018.08.035

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                    Zhao, Jie. Tue .  
"Measurements of the chiral magnetic effect with background isolation in 200 GeV Au+Au collisions at STAR".  United States.  https://doi.org/10.1016/j.nuclphysa.2018.08.035.  https://www.osti.gov/servlets/purl/1580374.

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@article{osti_1580374,

  title        = {Measurements of the chiral magnetic effect with background isolation in 200 GeV Au+Au collisions at STAR},

  author       = {Zhao, Jie},

  abstractNote = {Using two novel methods, pair invariant mass (minv) and comparative measurements with respect to reaction plane (ΨRP) and participant plane (ΨPP), we isolate the possible chiral magnetic effect (CME) from backgrounds in 200 GeV Au+Au collisions at STAR. The invariant mass method identifies the resonance background contributions, coupled with the elliptic flow (ν2), to the charge correlator CME observable (Δγ). At high mass (minv > 1.5 GeV/c2) where resonance contribution is small, we obtain the average Δγ magnitude. In the low mass region (minv > 1.5 GeV/c2), resonance peaks are observed in Δγ(minv). An event shape engineering (ESE) method is used to model the background shape in minv to extract the potential CME signal at low minv. In the comparative method, the ΨRP is assessed by spectator neutrons measured by the ZDCs, and the ΨPP by the 2nd-harmonic event plane measured by the TPC. The ν2 is stronger along ΨPP and weaker along ΨRP; in contrast, the magnetic field, mainly from spectator protons, is weaker along ΨPP and stronger along ΨRP. As a result, the Δγ measured with respect to ΨRP and ΨPP contain different amounts of CME and background, and can thus determine these two contributions. It is found that the possible CME signals with background isolation by these two novel methods are small, on the order of a few percent of the inclusive Δγ measurements.},

  doi          = {10.1016/j.nuclphysa.2018.08.035},

  journal      = {Nuclear Physics. A},

  number       = C,

  volume       = 982,

  place        = {United States},

  year         = {Tue Jan 22 00:00:00 EST 2019},

  month        = {Tue Jan 22 00:00:00 EST 2019}

}

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Works referenced in this record:

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Works referencing / citing this record:

Back-to-back relative-excess observable to identify the chiral magnetic effect
journal, January 2020

Feng, Yicheng; Zhao, Jie; Wang, Fuqiang
Physical Review C, Vol. 101, Issue 1
DOI: 10.1103/physrevc.101.014915

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Title: Measurements of the chiral magnetic effect with background isolation in 200 GeV Au+Au collisions at STAR

Abstract

Citation Formats

Possibility of Spontaneous Parity Violation in Hot QCD journal, July 1998

Parity violation in hot QCD: How to detect it journal, November 2004

Chiral magnetic and vortical effects in high-energy nuclear collisions—A status report journal, May 2016

Charge conservation at energies available at the BNL Relativistic Heavy Ion Collider and contributions to local parity violation observables journal, January 2011

Measurement of charge multiplicity asymmetry correlations in high-energy nucleus-nucleus collisions at s N N = 200 GeV journal, April 2014

Chiral magnetic effect search in p+Au, d+Au and Au+Au collisions at RHIC journal, January 2018

The effects of topological charge change in heavy ion collisions: “Event by event and violation” journal, May 2008

Ultra-relativistic nuclear collisions: Event shape engineering journal, February 2013

The RHIC zero-degree calorimeters journal, April 2001

Back-to-back relative-excess observable to identify the chiral magnetic effect journal, January 2020

Possibility of Spontaneous Parity Violation in Hot QCD
journal, July 1998

Parity violation in hot QCD: How to detect it
journal, November 2004

Chiral magnetic and vortical effects in high-energy nuclear collisions—A status report
journal, May 2016

Charge conservation at energies available at the BNL Relativistic Heavy Ion Collider and contributions to local parity violation observables
journal, January 2011

Measurement of charge multiplicity asymmetry correlations in high-energy nucleus-nucleus collisions at $\sqrt{s_{N N}} = 200$ GeV
journal, April 2014

Chiral magnetic effect search in p+Au, d+Au and Au+Au collisions at RHIC
journal, January 2018

The effects of topological charge change in heavy ion collisions: “Event by event and violation”
journal, May 2008

Ultra-relativistic nuclear collisions: Event shape engineering
journal, February 2013

The RHIC zero-degree calorimeters
journal, April 2001

Back-to-back relative-excess observable to identify the chiral magnetic effect
journal, January 2020