A novel invariant mass method to isolate resonance backgrounds from the chiral magnetic effect

Journal Article · 21 January 2019 · Nuclear Physics. A

DOI: https://doi.org/10.1016/j.nuclphysa.2018.08.006 · OSTI ID:1611952

Li, Hanlin ^[1]; Zhao, Jie ^[2]; Wang, Fuqiang  ^[3]

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1. Wuhan Univ. of Science and Technology, Wuhan, Hubei (China); DOE/OSTI
2. Purdue Univ., West Lafayette, IN (United States)
3. Huzhou Univ., Huzhou, Zhejiang (China); Purdue Univ., West Lafayette, IN (United States)

The Chiral Magnetic Effect (CME) refers to charge separation along a strong magnetic field, due to topological charge fluctuations in QCD. Charge correlation (Δγ) signals consistent with CME have been first observed almost a decade ago. It has also been known since then that the Δγ is contaminated by a major background from resonance decays coupled with elliptic flow. In this contribution, we propose differential Δγ measurements as function of the pair invariant mass (m_inv). The Δγ in the high minv region is essentially free of resonance backgrounds. In the low m_inv region, the Δγ backgrounds show resonance peaks. The CME signal, presumably smooth in m_inv, may thus be extracted from a two-component model fit. We demonstrate the feasibility and effectiveness of this novel method by using the AMPT and toy-model Monte-Carlo simulations. We also discuss an application of the method in data analysis.

• Research Organization: Purdue Univ., West Lafayette, IN (United States)
• Sponsoring Organization: National Natural Science Foundation of China (NNSFC); USDOE Office of Science (SC)
• Grant/Contract Number: SC0012910
• OSTI ID: 1611952
• Journal Information: Nuclear Physics. A, Journal Name: Nuclear Physics. A Journal Issue: C Vol. 982; ISSN 0375-9474
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English