{"@context":"http://schema.org","@id":"https://doi.org/10.17182/hepdata.156181.v1","@reverse":{"isBasedOn":[{"@type":"ScholarlyArticle","identifier":{"@type":"PropertyValue","propertyID":"URL","value":"https://inspirehep.net/literature/2879229"}},{"@id":"https://doi.org/10.1103/6ywq-gm61","@type":"JournalArticle"}]},"@type":"Dataset","additionalType":"Collection","author":{"@type":"Organization","name":"CMS Collaboration"},"creator":{"@type":"Organization","name":"CMS Collaboration"},"datePublished":"2025","description":"The polarization of the $\u039b$ and $\\overline\u039b$ hyperons along the beam direction has been measured in proton-lead (pPb) collisions at a center-of-mass energy per nucleon pair of 8.16 TeV. The data were obtained with the CMS detector at the LHC and correspond to an integrated luminosity of 186.0 $\\pm$ 6.5 nb$^{-1}$. A significant azimuthal dependence of the hyperon polarization, characterized by the second-order Fourier sine coefficient $P_{z,s2}$, is observed. The $P_{z,s2}$ values decrease as a function of charged particle multiplicity, but increase with transverse momentum. A hydrodynamic model that describes the observed $P_{z,s2}$ values in nucleus-nucleus collisions by introducing vorticity effects does not reproduce either the sign or the magnitude of the pPb results. These observations pose a challenge to the current theoretical implementation of spin polarization in heavy ion collisions and offer new insights into the origin of spin polarization in hadronic collisions at LHC energies.","hasPart":[{"@id":"https://doi.org/10.17182/hepdata.156181.v1/t1","@type":"Dataset","description":"The second-order Fourier sine coefficients of $\\Lambda$, $\\bar{\\Lambda}$ and $\\Lambda+\\bar{\\Lambda}$ polarizations along the beam direction as functions of $N_\\mathrm{trk}^\\mathrm{offline}$ in...","name":"Table 1"},{"@id":"https://doi.org/10.17182/hepdata.156181.v1/t2","@type":"Dataset","description":"The second-order Fourier sine coefficients of $\\Lambda+\\bar{\\Lambda}$ polarization along the beam direction as functions of $p_{T}$ in pPb collisions at...","name":"Table 2"},{"@id":"https://doi.org/10.17182/hepdata.156181.v1/t3","@type":"Dataset","description":"The second-order Fourier sine coefficients of $K_{S}^{0}$ polarization along the beam direction as functions of $N_\\mathrm{trk}^\\mathrm{offline}$ in pPb collisions at...","name":"Table 3"},{"@id":"https://doi.org/10.17182/hepdata.156181.v1/t4","@type":"Dataset","description":"The second-order Fourier sine coefficients of $\\Lambda$ polarization along the beam direction as functions of $N_\\mathrm{trk}^\\mathrm{offline}$ in pPb collisions at...","name":"Table 4"},{"@id":"https://doi.org/10.17182/hepdata.156181.v1/t5","@type":"Dataset","description":"The second-order Fourier sine coefficients of $\\bar{\\Lambda}$ polarization along the beam direction as functions of $N_\\mathrm{trk}^\\mathrm{offline}$ in pPb collisions at...","name":"Table 5"},{"@id":"https://doi.org/10.17182/hepdata.156181.v1/t6","@type":"Dataset","description":"The second-order Fourier sine coefficients of $\\Lambda+\\bar{\\Lambda}$ polarization along the beam direction as functions of $N_\\mathrm{trk}^\\mathrm{offline}$ in pPb collisions at...","name":"Table 6"}],"identifier":[{"@type":"PropertyValue","propertyID":"HEPDataRecord","value":"https://www.hepdata.net/record/ins2879229?version=1"},{"@type":"PropertyValue","propertyID":"HEPDataRecordAlt","value":"https://www.hepdata.net/record/156181"}],"inLanguage":"en","name":"Observation of $\\Lambda$ hyperon local polarization in pPb collisions at $\\sqrt{s_\\mathrm{NN}}$ = 8.16 TeV","provider":{"@type":"Organization","name":"HEPData"},"publisher":{"@type":"Organization","name":"HEPData"},"url":"https://www.hepdata.net/record/ins2879229?version=1","version":1}