Single spin asymmetry utilising relative luminosity

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Single spin asymmetry making use of relative luminosity

I also calculate the asymmetry via an alternative method, making use of Tai Sakuma's relative luminosity work. The left-right asymmetry is defined as

Definition of left-right asymmetry
Equation 1

where NL is the particle yield to the left of the polarised beam. The decomposition of the up/down yields into contributions from the four different beam polarisation permutations is the same as given in the cross-asymmetry section (equations 2 and 3). Here, the yields must be scaled by the appropriate relative luminosity, giving the following relations:

Contributions to blue beam counts, scaled for luminosity
Equation 2
Contributions to yellow beam counts, scaled for luminosity
Equation 3

The relative luminosities R4, R5 and R6 are the ratios of luminosity for, respectively, up-up, up-down and down-up bunches to that for down-down bunches. I record the particle yields for each polarisation permutation (i.e. spin bits) on a run-by-run basis, scale each by the appropriate relative luminosity for that run, then combine yields from all the runs in a given fill to give fill-by-fill yields. These are then used to calculate a fill-by-fill raw asymmetry, which is scaled by the beam polarisation. The figures below show the resultant fill-by-fill asymmetry for each beam and particle species, summed over all pT. The fits are again satisfactory, and give asymmetries consistent with zero within errors, as expected.

K0s blue beam asymmetry using relative luminosity
Figure 1a: Blue beam asymmetry for K0S
K0s yellow beam asymmetry using relative luminosity
Figure 1b: Yellow beam asymmetry for K0S
Lambda blue beam asymmetry using relative luminosity
Figure 2a: Blue beam asymmetry for Λ
Lambda yellow beam asymmetry using relative luminosity
Figure 2b: Yellow beam asymmetry for Λ