Strange hadron collectivity in pPb and PbPb collisions

ARXIV EPRINT: 2205.00080 (https://arxiv.org/abs/2205.00080).Copyright © 2023 CERN, for the benefit of the CMS Collaboration. The collective behavior of $${\textrm{K}}_{\textrm{S}}^0$$ K S 0 and $$\Lambda /\overline{\Lambda}$$ Λ / Λ ¯ strange hadrons is studied by measuring the elliptic azimuthal anisotropy (v2) using the scalar-product and multiparticle correlation methods. Proton-lead (pPb) collisions at a nucleon-nucleon center-of-mass energy $$\sqrt{s_{\textrm{NN}}}$$ s NN = 8.16 TeV and lead-lead (PbPb) collisions at $$\sqrt{s_{\textrm{NN}}}$$ s NN = 5.02 TeV collected by the CMS experiment at the LHC are investigated. Nonflow effects in the pPb collisions are studied by using a subevent cumulant analysis and by excluding events where a jet with transverse momentum greater than 20 GeV is present. The strange hadron v2 values extracted in pPb collisions via the four- and six-particle correlation method are found to be nearly identical, suggesting the collective behavior. Comparisons of the pPb and PbPb results for both strange hadrons and charged particles illustrate how event-by-event flow fluctuations depend on the system size.SCOAP

Strange hadron collectivity in pPb and PbPb collisions

Abstract The collective behavior of K S 0 $${\textrm{K}}_{\textrm{S}}^0$$ and Λ / Λ ¯ $$\Lambda /\overline{\Lambda}$$ strange hadrons is studied by measuring the elliptic azimuthal anisotropy (v 2) using the scalar-product and multiparticle correlation methods. Proton-lead (pPb) collisions at a nucleon-nucleon center-of-mass energy s NN $$\sqrt{s_{\textrm{NN}}}$$ = 8.16 TeV and lead-lead (PbPb) collisions at s NN $$\sqrt{s_{\textrm{NN}}}$$ = 5.02 TeV collected by the CMS experiment at the LHC are investigated. Nonflow effects in the pPb collisions are studied by using a subevent cumulant analysis and by excluding events where a jet with transverse momentum greater than 20 GeV is present. The strange hadron v 2 values extracted in pPb collisions via the four- and six-particle correlation method are found to be nearly identical, suggesting the collective behavior. Comparisons of the pPb and PbPb results for both strange hadrons and charged particles illustrate how event-by-event flow fluctuations depend on the system size

Strange hadron collectivity in pPb and PbPb collisions

The collective behavior of ${\textrm{K}}_{\textrm{S}}^0$ and $\Lambda /\overline{\Lambda}$ strange hadrons is studied by measuring the elliptic azimuthal anisotropy (v$_{2}$) using the scalar-product and multiparticle correlation methods. Proton-lead (pPb) collisions at a nucleon-nucleon center-of-mass energy $\sqrt{s_{\textrm{NN}}}$ = 8.16 TeV and lead-lead (PbPb) collisions at $\sqrt{s_{\textrm{NN}}}$ = 5.02 TeV collected by the CMS experiment at the LHC are investigated. Nonflow effects in the pPb collisions are studied by using a subevent cumulant analysis and by excluding events where a jet with transverse momentum greater than 20 GeV is present. The strange hadron v$_{2}$ values extracted in pPb collisions via the four- and six-particle correlation method are found to be nearly identical, suggesting the collective behavior. Comparisons of the pPb and PbPb results for both strange hadrons and charged particles illustrate how event-by-event flow fluctuations depend on the system size.[graphic not available: see fulltext

Measurement of b jet shapes in proton-proton collisions at s=5.02 TeV

We present the first study of charged-hadron production associated with jets originating from b quarks in proton-proton collisions at a center-of-mass energy of 5.02 TeV. The data sample used in this study was collected with the CMS detector at the CERN LHC and corresponds to an integrated luminosity of 27.4 pb(-1). To characterize the jet substructure, the differential jet shapes, defined as the normalized transverse momentum distribution of charged hadrons as a function of angular distance from the jet axis, are measured for b jets. In addition to the jet shapes, the per-jet yields of charged particles associated with b jets are also quantified, again as a function of the angular distance with respect to the jet axis. Extracted jet shape and particle yield distributions for b jets are compared with results for inclusive jets, as well as with the predictions from the pythia and herwig++ event generators

Strange hadron collectivity in pPb and PbPb collisions

International audienceThe collective behavior of ${\textrm{K}}_{\textrm{S}}^0$ and $\Lambda /\overline{\Lambda}$ strange hadrons is studied by measuring the elliptic azimuthal anisotropy (v$_{2}$) using the scalar-product and multiparticle correlation methods. Proton-lead (pPb) collisions at a nucleon-nucleon center-of-mass energy $\sqrt{s_{\textrm{NN}}}$ = 8.16 TeV and lead-lead (PbPb) collisions at $\sqrt{s_{\textrm{NN}}}$ = 5.02 TeV collected by the CMS experiment at the LHC are investigated. Nonflow effects in the pPb collisions are studied by using a subevent cumulant analysis and by excluding events where a jet with transverse momentum greater than 20 GeV is present. The strange hadron v$_{2}$ values extracted in pPb collisions via the four- and six-particle correlation method are found to be nearly identical, suggesting the collective behavior. Comparisons of the pPb and PbPb results for both strange hadrons and charged particles illustrate how event-by-event flow fluctuations depend on the system size.[graphic not available: see fulltext