Measurement of groomed jet substructure observables in p+p collisions at $$\sqrt{s} =$$ 200 GeV with STAR
In this letter, measurements of the shared momentum fraction ( ) and the groomed jet radius ( ), as defined in the SoftDrop algorithm, are reported in p+p collisions at GeV collected by the STAR experiment. These substructure observables are differentially measured for jets of varying resolution parameters from in the transverse momentum range GeV/c. These studies show that, in the range accessible at GeV and with increasing jet resolution parameter and jet transverse momentum, the distribution asymptotically converges to the DGLAP splitting kernel for a quark radiating a gluon. The groomed jet radius measurements reflect a momentum-dependent narrowing of the jet structure for jets of a given resolution parameter, i.e., the larger the , the narrower the first splitting. For the first time, these fully corrected measurements are compared to Monte Carlo generators with leading order QCD matrix elements and leading log in the parton shower, and to state-of-the-art theoretical calculations at next-to-leading-log accuracy. We observe that PYTHIA 6 with parameters tuned to reproduce RHIC measurements is able to quantitatively describe data, whereas PYTHIA 8 and HERWIG 7, tuned to reproduce LHC data, are unable to provide a simultaneous description of both and , resulting in opportunities for fine parameter tuning of these models for p+p collisions at RHIC energies. We also find that the theoretical calculations without non-perturbative corrections are able to qualitatively describe the trend in data for jets of large resolution parameters at high , but fail at small jet resolution parameters and low jet transverse momenta.
- Research Organization:
- Texas A & M Univ., College Station, TX (United States); Brookhaven National Lab. (BNL), Upton, NY (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Nuclear Physics (NP); National Science Foundation (NSF)
- Contributing Organization:
- STAR Collaboration
- Grant/Contract Number:
- SC0015636; SC0012704; AC02-05CH11231
- OSTI ID:
- 1787646
- Alternate ID(s):
- OSTI ID: 1670683; OSTI ID: 1713315
- Report Number(s):
- BNL-219906-2020-JAAM; TRN: US2210488
- Journal Information:
- Physics Letters. B, Vol. 811; ISSN 0370-2693
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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