Background estimator for jet studies in p+p and A+A collisions

Yacine Mehtar-Tani; Alba Soto-Ontoso; Marta Verweij

doi:10.1103/PhysRevD.100.114023

Background estimator for jet studies in p+p and A+A collisions

Yacine Mehtar-Tani
, Alba Soto-Ontoso
, Marta Verweij

Subatomic Physics

Brookhaven National Laboratory

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

Experimentally, jet physics studies face an unavoidable task: Distinguishing, at the detector level, the particles produced in the hard partonic scattering from the ones created in unrelated soft processes such as pileup interactions in high-luminosity proton-proton scattering or the underlying event in heavy-ion collisions. The fluctuating nature of the background constitutes the main source of uncertainty for any subtraction algorithm. Aiming at mitigating the effect of such fluctuations, we present a new method to estimate the background contribution to the transverse momentum on a jet-by-jet basis. Our approach is based on estimating the median background momentum density stored above a pT-cut applied at the constituent level and an experimentally accessible correction term related to the signal contribution below the cut. This allows to trade part of the uncertainty due to background contamination for that of the signal below the cut, similarly to the SoftKiller method. We propose to reduce the fluctuations of the latter by exploiting intrinsic correlations among the soft and hard sectors generated in the branching process of QCD jets. Our data-driven approach is tested against pythia8 and jewel dijet events embedded in minimum bias events and thermal background, respectively, and compared to the area-median and SoftKiller methods. The main result of this study is a ∼5%-35% improvement on the resolution of the reconstructed jet pT compared to previous methods in both high-luminosity proton-proton and heavy-ion collisions.

Original language	English
Article number	114023
Number of pages	8
Journal	Physical Review D
Volume	100
Issue number	11
DOIs	https://doi.org/10.1103/PhysRevD.100.114023
Publication status	Published - 13 Dec 2019

Funding

We would like to express our gratitude to Antonio Bueno, Megan Connors, Kolja Kauder and Brian Page for helpful discussions during the realization of this work. We thank Gavin Salam for a careful reading of the manuscript and sharing his insights into the SoftKiller method. Y. M. T. and A. S. O.’s work was supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Contract No. DE- SC0012704, and by Laboratory Directed Research and Development (LDRD) funds from Brookhaven Science Associates. [1] 1 K. Adcox ( PHENIX Collaboration ) , Phys. Rev. Lett. 88 , 022301 ( 2001 ). PRLTAO 0031-9007 10.1103/PhysRevLett.88.022301 [2] 2 K. Aamodt ( ALICE Collaboration ) , Phys. Lett. B 696 , 30 ( 2011 ). PYLBAJ 0370-2693 10.1016/j.physletb.2010.12.020 [3] 3 G. Aad ( ATLAS Collaboration ) , Phys. Rev. Lett. 105 , 252303 ( 2010 ). PRLTAO 0031-9007 10.1103/PhysRevLett.105.252303 [4] 4 A. M. Sirunyan ( CMS Collaboration ) , Phys. Rev. Lett. 120 , 142302 ( 2018 ). PRLTAO 0031-9007 10.1103/PhysRevLett.120.142302 [5] 5 K. Kauder ( STAR Collaboration ) , Nucl. Phys. A967 , 516 ( 2017 ). NUPBBO 0550-3213 10.1016/j.nuclphysa.2017.07.004 [6] 6 H. A. Andrews , arXiv:1808.03689 . [7] 7 S. Catani , Y. L. Dokshitzer , M. H. Seymour , and B. R. Webber , Nucl. Phys. B406 , 187 ( 1993 ). NUPBBO 0550-3213 10.1016/0550-3213(93)90166-M [8] 8 Y. L. Dokshitzer , G. D. Leder , S. Moretti , and B. R. Webber , J. High Energy Phys. 08 ( 1997 ) 001 . JHEPFG 1029-8479 10.1088/1126-6708/1997/08/001 [9] 9 M. Cacciari , G. P. Salam , and G. Soyez , J. High Energy Phys. 04 ( 2008 ) 063 . JHEPFG 1029-8479 10.1088/1126-6708/2008/04/063 [10] 10 B. Abelev ( ALICE Collaboration ) , J. High Energy Phys. 03 ( 2012 ) 053 . JHEPFG 1029-8479 10.1007/JHEP03(2012)053 [11] 11 S. Acharya ( ALICE Collaboration ) , Phys. Lett. B 776 , 249 ( 2018 ). PYLBAJ 0370-2693 10.1016/j.physletb.2017.11.044 [12] 12 ATLAS Collaboration , ATLAS Report No. 2018/014 , 2018 . [13] 13 Y. Mehtar-Tani , A. Soto-Ontoso , and M. Verweij (to be published). [14] 14 M. Cacciari and G. P. Salam , Phys. Lett. B 659 , 119 ( 2008 ). PYLBAJ 0370-2693 10.1016/j.physletb.2007.09.077 [15] 15 M. Cacciari , G. P. Salam , and G. Soyez , Eur. Phys. J. C 75 , 59 ( 2015 ). EPCFFB 1434-6044 10.1140/epjc/s10052-015-3267-2 [16] 16 P. Berta , M. Spousta , D. W. Miller , and R. Leitner , J. High Energy Phys. 06 ( 2014 ) 092 . JHEPFG 1029-8479 10.1007/JHEP06(2014)092 [17] 17 R. Haake and C. Loizides , Phys. Rev. C 99 , 064904 ( 2019 ). PRVCAN 2469-9985 10.1103/PhysRevC.99.064904 [18] 18 T. Sjostrand , S. Mrenna , and P. Z. Skands , Comput. Phys. Commun. 178 , 852 ( 2008 ). CPHCBZ 0010-4655 10.1016/j.cpc.2008.01.036 [19] 19 ATLAS and CMS Collaborations , arXiv:1902.10229 . [20] 20 K. C. Zapp , J. Stachel , and U. A. Wiedemann , J. High Energy Phys. 07 ( 2011 ) 118 . JHEPFG 1029-8479 10.1007/JHEP07(2011)118 [21] 21 M. Cacciari , G. P. Salam , and G. Soyez , Eur. Phys. J. C 72 , 1896 ( 2012 ). EPCFFB 1434-6044 10.1140/epjc/s10052-012-1896-2 [22] 22 A. J. Larkoski , J. Thaler , and W. J. Waalewijn , J. High Energy Phys. 11 ( 2014 ) 129 . JHEPFG 1029-8479 10.1007/JHEP11(2014)129 [23] 23 Y. Mehtar-Tani , J. G. Milhano , and K. Tywoniuk , Int. J. Mod. Phys. A 28 , 1340013 ( 2013 ). IMPAEF 0217-751X 10.1142/S0217751X13400137 [24] 24 P. T. Komiske , E. M. Metodiev , B. Nachman , and M. D. Schwartz , J. High Energy Phys. 12 ( 2017 ) 051 . JHEPFG 1029-8479 10.1007/JHEP12(2017)051

Access to Document

10.1103/PhysRevD.100.114023

PhysRevD.100.114023Final published version, 341 KB

Cite this

@article{e10ff9e5ea314687908233f8f929693d,

title = "Background estimator for jet studies in p+p and A+A collisions",

abstract = "Experimentally, jet physics studies face an unavoidable task: Distinguishing, at the detector level, the particles produced in the hard partonic scattering from the ones created in unrelated soft processes such as pileup interactions in high-luminosity proton-proton scattering or the underlying event in heavy-ion collisions. The fluctuating nature of the background constitutes the main source of uncertainty for any subtraction algorithm. Aiming at mitigating the effect of such fluctuations, we present a new method to estimate the background contribution to the transverse momentum on a jet-by-jet basis. Our approach is based on estimating the median background momentum density stored above a pT-cut applied at the constituent level and an experimentally accessible correction term related to the signal contribution below the cut. This allows to trade part of the uncertainty due to background contamination for that of the signal below the cut, similarly to the SoftKiller method. We propose to reduce the fluctuations of the latter by exploiting intrinsic correlations among the soft and hard sectors generated in the branching process of QCD jets. Our data-driven approach is tested against pythia8 and jewel dijet events embedded in minimum bias events and thermal background, respectively, and compared to the area-median and SoftKiller methods. The main result of this study is a ∼5\%-35\% improvement on the resolution of the reconstructed jet pT compared to previous methods in both high-luminosity proton-proton and heavy-ion collisions.",

author = "Yacine Mehtar-Tani and Alba Soto-Ontoso and Marta Verweij",

year = "2019",

month = dec,

day = "13",

doi = "10.1103/PhysRevD.100.114023",

language = "English",

volume = "100",

journal = "Physical Review D",

issn = "2470-0010",

publisher = "American Physical Society",

number = "11",

}

TY - JOUR

T1 - Background estimator for jet studies in p+p and A+A collisions

AU - Mehtar-Tani, Yacine

AU - Soto-Ontoso, Alba

AU - Verweij, Marta

PY - 2019/12/13

Y1 - 2019/12/13

N2 - Experimentally, jet physics studies face an unavoidable task: Distinguishing, at the detector level, the particles produced in the hard partonic scattering from the ones created in unrelated soft processes such as pileup interactions in high-luminosity proton-proton scattering or the underlying event in heavy-ion collisions. The fluctuating nature of the background constitutes the main source of uncertainty for any subtraction algorithm. Aiming at mitigating the effect of such fluctuations, we present a new method to estimate the background contribution to the transverse momentum on a jet-by-jet basis. Our approach is based on estimating the median background momentum density stored above a pT-cut applied at the constituent level and an experimentally accessible correction term related to the signal contribution below the cut. This allows to trade part of the uncertainty due to background contamination for that of the signal below the cut, similarly to the SoftKiller method. We propose to reduce the fluctuations of the latter by exploiting intrinsic correlations among the soft and hard sectors generated in the branching process of QCD jets. Our data-driven approach is tested against pythia8 and jewel dijet events embedded in minimum bias events and thermal background, respectively, and compared to the area-median and SoftKiller methods. The main result of this study is a ∼5%-35% improvement on the resolution of the reconstructed jet pT compared to previous methods in both high-luminosity proton-proton and heavy-ion collisions.

AB - Experimentally, jet physics studies face an unavoidable task: Distinguishing, at the detector level, the particles produced in the hard partonic scattering from the ones created in unrelated soft processes such as pileup interactions in high-luminosity proton-proton scattering or the underlying event in heavy-ion collisions. The fluctuating nature of the background constitutes the main source of uncertainty for any subtraction algorithm. Aiming at mitigating the effect of such fluctuations, we present a new method to estimate the background contribution to the transverse momentum on a jet-by-jet basis. Our approach is based on estimating the median background momentum density stored above a pT-cut applied at the constituent level and an experimentally accessible correction term related to the signal contribution below the cut. This allows to trade part of the uncertainty due to background contamination for that of the signal below the cut, similarly to the SoftKiller method. We propose to reduce the fluctuations of the latter by exploiting intrinsic correlations among the soft and hard sectors generated in the branching process of QCD jets. Our data-driven approach is tested against pythia8 and jewel dijet events embedded in minimum bias events and thermal background, respectively, and compared to the area-median and SoftKiller methods. The main result of this study is a ∼5%-35% improvement on the resolution of the reconstructed jet pT compared to previous methods in both high-luminosity proton-proton and heavy-ion collisions.

U2 - 10.1103/PhysRevD.100.114023

DO - 10.1103/PhysRevD.100.114023

M3 - Article

AN - SCOPUS:85076542031

SN - 2470-0010

VL - 100

JO - Physical Review D

JF - Physical Review D

IS - 11

M1 - 114023

ER -

Background estimator for jet studies in p+p and A+A collisions

Abstract

Funding

Access to Document

Fingerprint

Cite this