Methods for a blind analysis of isobar data collected by the STAR collaboration

作者：Adam, J.; Adamczyk, L.; Adams, J. R.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Anderson, D. M.; Aparin, A.; Aschenauer, E. C.; Ashraf, M. U.; Atetalla, F. G.; Attri, A.; Averichev, G. S.; Bairathi, V.; Barish, K.; Behera, A.; Bellwied, R.; Bhasin, A.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Brandenburg, J. D.; Brandin, A. V.; Butterworth, J.; Caines, H.; de la Barca Sanchez, M. Calderon; Cebra, D.; Chakaberia, I.; Chaloupka, P.

来源：Nuclear Science and Techniques, 2021, 32(5): 48.

DOI：10.1007/s41365-021-00878-y

• Blind analysis
• Chiral magnetic effect
• Heavy-ion collisions

In 2018, the STAR collaboration collected data from 4496</mml:msubsup>Ru+4496</mml:msubsup>Ru and 4096Zr+4096Zr at <mml:msqrt><mml:msub>sNN</mml:msqrt>=200 GeV to search for the presence of the chiral magnetic effect in collisions of nuclei. The isobar collision species alternated frequently between 4496Ru+4496Ru and 4096Zr+4096Zr. In order to conduct blind analyses of studies related to the chiral magnetic effect in these isobar data, STAR developed a three-step blind analysis procedure. Analysts are initially provided a "reference sample" of data, comprised of a mix of events from the two species, the order of which respects time-dependent changes in run conditions. After tuning analysis codes and performing time-dependent quality assurance on the reference sample, analysts are provided a species-blind sample suitable for calculating efficiencies and corrections for individual approximate to 30-min data-taking runs. For this sample, species-specific information is disguised, but individual output files contain data from a single isobar species. Only run-by-run corrections and code alteration subsequent to these corrections are allowed at this stage. Following these modifications, the "frozen" code is passed over the fully un-blind data, completing the blind analysis. As a check of the feasibility of the blind analysis procedure, analysts completed a "mock data challenge," analyzing data from Au+Au collisions at <mml:msqrt><mml:msub>sNN</mml:msqrt>=27 GeV, collected in 2018. The Au+Au data were prepared in the same manner intended for the isobar blind data. The details of the blind analysis procedure and results from the mock data challenge are presented.