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SoftKiller, a particle-level pileup removal method.

Cacciari M, Salam GP, Soyez G - Eur Phys J C Part Fields (2015)

Bottom Line: It removes the softest particles in an event, up to a transverse momentum threshold that is determined dynamically on an event-by-event basis.In simulations, this simple procedure appears to be reasonably robust and brings superior jet resolution performance compared to existing jet-based approaches.It is also nearly two orders of magnitude faster than methods based on jet areas.

View Article: PubMed Central - PubMed

Affiliation: Université Paris Diderot, Paris, France ; Sorbonne Universités, UPMC Univ Paris 06, UMR 7589, LPTHE, 75005 Paris, France ; CNRS, UMR 7589, LPTHE, 75005 Paris, France.

ABSTRACT

Existing widely used pileup removal approaches correct the momenta of individual jets. In this article we introduce an event-level, particle-based pileup correction procedure, SoftKiller. It removes the softest particles in an event, up to a transverse momentum threshold that is determined dynamically on an event-by-event basis. In simulations, this simple procedure appears to be reasonably robust and brings superior jet resolution performance compared to existing jet-based approaches. It is also nearly two orders of magnitude faster than methods based on jet areas.

No MeSH data available.


Same as Fig. 5, for events with charged-hadron subtraction (CHS). Note that the grid size used for the SoftKiller curves has been set to
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Fig10: Same as Fig. 5, for events with charged-hadron subtraction (CHS). Note that the grid size used for the SoftKiller curves has been set to

Mentions: One important change that arises from applying SK just to the neutral particles is that there is a reduced contribution of low- hard-event particles. This means that for a given actual amount of pileup contamination (in terms of visible transverse momentum per unit area), one can afford to cut more aggressively, i.e. raise the as compared to the full particle-level case, because for a given there will be a reduced loss of hard-event particles. This can be achieved through a moderate increase in the grid spacing, to . Figure 10 shows the results, with the shift (left) and dispersion (right) for the jet in dijet and samples. The SK method continues to bring an improvement, though that improvement is slightly more limited than in the particle-level case. We attribute this reduced improvement to the fact that SK’s greatest impact is at very high pileup, and for a given , SK with CHS is effectively operating at lower pileup levels than without CHS. A further study with our toy CHS simulation concerns lepton isolation and is given in Appendix E.Fig. 10


SoftKiller, a particle-level pileup removal method.

Cacciari M, Salam GP, Soyez G - Eur Phys J C Part Fields (2015)

Same as Fig. 5, for events with charged-hadron subtraction (CHS). Note that the grid size used for the SoftKiller curves has been set to
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4376401&req=5

Fig10: Same as Fig. 5, for events with charged-hadron subtraction (CHS). Note that the grid size used for the SoftKiller curves has been set to
Mentions: One important change that arises from applying SK just to the neutral particles is that there is a reduced contribution of low- hard-event particles. This means that for a given actual amount of pileup contamination (in terms of visible transverse momentum per unit area), one can afford to cut more aggressively, i.e. raise the as compared to the full particle-level case, because for a given there will be a reduced loss of hard-event particles. This can be achieved through a moderate increase in the grid spacing, to . Figure 10 shows the results, with the shift (left) and dispersion (right) for the jet in dijet and samples. The SK method continues to bring an improvement, though that improvement is slightly more limited than in the particle-level case. We attribute this reduced improvement to the fact that SK’s greatest impact is at very high pileup, and for a given , SK with CHS is effectively operating at lower pileup levels than without CHS. A further study with our toy CHS simulation concerns lepton isolation and is given in Appendix E.Fig. 10

Bottom Line: It removes the softest particles in an event, up to a transverse momentum threshold that is determined dynamically on an event-by-event basis.In simulations, this simple procedure appears to be reasonably robust and brings superior jet resolution performance compared to existing jet-based approaches.It is also nearly two orders of magnitude faster than methods based on jet areas.

View Article: PubMed Central - PubMed

Affiliation: Université Paris Diderot, Paris, France ; Sorbonne Universités, UPMC Univ Paris 06, UMR 7589, LPTHE, 75005 Paris, France ; CNRS, UMR 7589, LPTHE, 75005 Paris, France.

ABSTRACT

Existing widely used pileup removal approaches correct the momenta of individual jets. In this article we introduce an event-level, particle-based pileup correction procedure, SoftKiller. It removes the softest particles in an event, up to a transverse momentum threshold that is determined dynamically on an event-by-event basis. In simulations, this simple procedure appears to be reasonably robust and brings superior jet resolution performance compared to existing jet-based approaches. It is also nearly two orders of magnitude faster than methods based on jet areas.

No MeSH data available.