Pile-up Mitigation: Straw Picker

Table of Contents

• Using all particles
• Using neutral particles
• Using charged particles

Using all particles

• Identify centers of hard-scatter jets by clustering all particles in the event.
• Order clustered jets by P_T and take jets with P_T higher than P_T min, but no more than N_max = 12.
• Subtract areas of the jets from detector area and remove all tracks associated with the jets.
• Divide sum of P_T left in the event by the area.

Plots

Resolution

4 Tops

Dijets

Z'

Bias

4 Tops

Dijets

Z'

ρ Difference

4 Tops

Dijets

Z'

Using neutral particles

• Identify centers of hard-scatter jets by clustering neutral particles in the event.
• Order clustered jets by P_T and take jets with P_T higher than P_T min, but no more than N_max = 12.
• Subtract areas of the jets from detector area and remove all tracks associated with the jets.
• Divide sum of P_T left in the event by the area.

Plots

Resolution

4 Tops

Dijets

Z'

Bias

4 Tops

Dijets

Z'

ρ Difference

4 Tops

Dijets

Z'

Using charged signal particles

Strategy

1. Identify centers of hard-scatter by jet clustering charged signal particles in the event.
2. Discard clustered jets with $p_\mathrm{T}$ smaller than $p_\mathrm{T}^{\min}$. Remaining jets order by $p_\mathrm{T}$ and keep at most $N^{\max}$.
3. Tag all tiles which centers are closer to the centers of the jets than jet radius $R$.
4. In every tile sum $p_\mathrm{T}$ of all deposits, excluding tagged ones. Tagged tiles exclude from the list of tiles.
5. Determine median $p_\mathrm{T}^\mathrm{median}$ and divide it by tile area to obtain $\rho_\mathrm{straw}$

Settings

• Grid spacing: 0.5
• jet $R = 0.7$
• $p_\mathrm{T}^{\min} = 5$ GeV
• $N^{\max} = 12$

Plots $R=0.7$

Resolution

4 Tops

Dijets

Z'

Bias

4 Tops

Dijets

Z'

ρ Difference

4 Tops

Dijets

Z'

Plots $R=0.2$

Resolution

4 Tops

Dijets

Bias

4 Tops

Dijets

ρ Difference

4 Tops

Dijets