This blog contains studies performed that will show how global and helicity spin alignment parameters (including off-diagonal spin density matrix elements) affect each other. Elliptic flow (v2) plays a crucial role and is varied in these studies.

Note that these are all shown for MC (No detector effects).

All of these studies are conducted for 19.6 GeV.

Information about the simulation:

• Pythia decay
• Flat rapidity input
• pT spectra is from published data in the range |y| < 0.5

Here we will input varying values of helicity frame spin density matrix elements and see the effect on the extracted global parameters from the same simulation:

• Global parameters vs Helicity parameters compared for no v2 and v2 from preliminary results: STAR/system/files/userfiles/6551/GlobalvsHelicity_parametercomparison_Mc_v2.pdf
• Global parameters vs v2 for various inputs of helicity parameters: STAR/system/files/userfiles/6551/GlobalvsHelicity_parametercomparison_Mc_v2_Variance.pdf
• Helicity parameters vs v2 for various input of helicity parameters (QA check): STAR/system/files/userfiles/6551/HelicityvsHelicity_parametercomparison_Mc_v2_Variance.pdf

Here we will input varying values of global frame spin density matrix elements and see the effect on the extracted helicity parameters from the same simulation:

• Helicity parameters vs Global parameters compared for no v2 and v2 from preliminary results: STAR/system/files/userfiles/6551/HelicityvsGlobal_parametercomparison_Mc_v2_On_Off.pdf
• Helicity parameters vs v2 for various inputs of global parameters: STAR/system/files/userfiles/6551/HelicityvsGlobal_parametercomparison_Mc_v2_Variance.pdf
• Global parameters vs v2 for various input of global parameters (QA check): STAR/system/files/userfiles/6551/GlobalvsGlobal_parametercomparison_Mc_v2_Variance.pdf