April 2009 posts

The STAR spin program with longitudinally polarized proton beams

ROOT implementation for LDA:

LDA configuration: default

LDA input parameters:

- Energy fraction in 3x3 cluster within a r=0.7 radius: r3x3
- Photon-jet pt balance: [pt_gamma-pt_jet]/pt_gamma
- Number of charge tracks within r=0.7 around gamma candidate
- Number of Endcap towers fired within r=0.7 around gamma candidate
- Number of Barrel towers fired within r=0.7 around gamma candidate

**Figure 1:** LDA discriminant (no SMD involved in training)

**Figure 2:** LDA (no SMD): Efficiency, rejection, purity vs. discriminant

**Figure 3:** SMD energy in 25 central strips (LDA-dsicriminant>0, no pre-shower1 cut)

**Figure 4:** SMD energy in 25 central strips (LDA-dsicriminant>0, pre-shower1 < 10MeV)

**Figure 5:** Maximum residual (LDA-dsicriminant>0, no pre-shower1 cut)

**Figure 6:** Maximum residual (LDA-dsicriminant>0, pre-shower1 < 10MeV)

SMD info added:

a) energy in 5 central srtips

b) maximum sided residual

**Figure 7:**LDA with SMD: Efficiency, rejection, purity vs. LDA discriminant

**Figure 8:** LDA discriminant with SMD

**Figure 9:** Maximum residual (SMD LDA-dsicriminant>0, pre-shower1 < 10MeV)

**Figure 10:**LDA (no SMD): Efficiency, rejection, purity plots

**Figure 11:** LDA with SMD: Efficiency, rejection, purity plots

ROOT implementation for LDA:

LDA configuration: default

LDA input parameters (includes SMD inromation of the distance from max sided residual plot):

- Energy fraction in 3x3 cluster within a r=0.7 radius: r3x3
- Photon-jet pt balance: [pt_gamma-pt_jet]/pt_gamma
- Number of charge tracks within r=0.7 around gamma candidate
- Number of Endcap towers fired within r=0.7 around gamma candidate
- Number of Barrel towers fired within r=0.7 around gamma candidate
- Distance to 80% cut line (see this link for more details)

The number of strips in SMD u or v planes is required to be greater than 3

**Figure 1:** SMD energy in 25 central strips sorted by pre-shower energy

- Upper left: pre1=0, pre2=0
- Upper right: pre1=0, pre2>0
- Lower left: 0<4MeV
- Lower right: 4<10MeV

Right plot for each pre-shower condition shows the ratio of pp2006 data to sum of the Monte-Carlo samples

**Colour coding**:

black pp2006 data, red gamma-jet MC, green QCD MC, blue gamma-jet+QCD

(combined plot for all pre-shoer bins can be found here)

**Figure 2:** SMD energy in 5 central strips sorted by pre-shower energy

(combined plot can be found here)

**Figure 3:** Maximum residual sorted by pre-shower energy

(combined plot can be found here)

**Figure 4:** LDA discriminant. Note: LDA algo trained for each pre-shower condition independently

**Figure 5:** LDA: Efficiency, rejection, purity vs. discriminant, sorted by pre-shower energy

**Figure 6:** LDA: Efficiency, rejection, purity plots sorted by pre-shower energy

For each pre-shower condition each plot has 4 figures:

- u-left: rejection vs. efficiency
- u-right: purity vs. efficiency
- l-left: purity vs. rejection
- l-right: significance (signal/sqrt{signal+background}) vs. efficiency