Probing small Bjorken-$x$ nuclear gluonic structure via coherent J/$\psi$ photoproduction in ultraperipheral PbPb collisions at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV

The CMS collaboration
Phys.Rev.Lett. 131 (2023) 262301, 2023.

Abstract
Quasireal photons exchanged in relativistic heavy ion interactions are powerful probes of the gluonic structure of nuclei. The coherent J/$\psi$ photoproduction cross section in ultraperipheral lead-lead collisions is measured as a function of photon-nucleus center-of-mass energies per nucleon (W$^\text{Pb}_{\gamma\text{N}}$), over a wide range of 40 $\lt$ W$^\text{Pb}_{\gamma\text{N}}$$\lt$ 400 GeV. Results are obtained using data at the nucleon-nucleon center-of-mass energy of 5.02 TeV collected by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of 1.52 nb$^{-1}$. The cross section is observed to rise rapidly at low W$^\text{Pb}_{\gamma\text{N}}$, and plateau above W$^\text{Pb}_{\gamma\text{N}}$$\approx$ 40 GeV, up to 400 GeV, a new regime of small Bjorken-$x$ ($\approx$ 6 $\times$ 10$^{-5}$) gluons being probed in a heavy nucleus. The observed energy dependence is not predicted by current quantum chromodynamic models.

  • Table 1

    Data from Figure 2

    10.17182/hepdata.138867.v2/t1

    The differential coherent $\mathrm{J}/\psi$ photoproduction cross section as a function of rapidity, in different neutron multiplicity classes: 0n0n, 0nXn, XnXn...

  • Table 2

    Data from Figure 3

    10.17182/hepdata.138867.v2/t2

    The total coherent $\mathrm{J}/\psi$ photoproduction cross section as a function of photon-nuclear center-of-mass energy per nucleon $W_{\gamma \mathrm{N}}^{\mathrm{Pb}}$, measured in...

  • Table 3

    Data from Figure 4

    10.17182/hepdata.138867.v2/t3

    The nuclear gluon suppression factor $R_{\mathrm{g}}^{\mathrm{Pb}}$ as a function of Bjorken $x$ extracted from the CMS measurement of the coherent...

  • Table 4

    Photon flux values used in Equation 2

    10.17182/hepdata.138867.v2/t4

    The photon flux values from STARLight as a function of rapidity, in different neutron multiplicity classes: 0n0n, 0nXn, and XnXn.

  • Flux Covariance Matrix 0n0n

    Covariance matrix for 0n0n

    10.17182/hepdata.138867.v2/t5

    The covariance matrix for the flux in the 0n0n neutron multiplicity class.

  • Flux Covariance Matrix 0nXn

    Covariance matrix for 0nXn

    10.17182/hepdata.138867.v2/t6

    The covariance matrix for the flux in the 0nXn neutron multiplicity class.

  • Flux Covariance Matrix XnXn

    Covariance matrix for XnXn

    10.17182/hepdata.138867.v2/t7

    The covariance matrix for the flux in the XnXn neutron multiplicity class.

  • Total covariance matrix

    Total covariance matrix for data from Figure 3

    10.17182/hepdata.138867.v2/t8

    The total covariance matrix of the total coherent photoproduction cross section as a function of photon-nuclear center-of-mass energy per nucleon...

  • Experimental covariance matrix

    Experimental covariance matrix for data from Figure 3

    10.17182/hepdata.138867.v2/t9

    The experimental covariance matrix of the total coherent photoproduction cross section as a function of photon-nuclear center-of-mass energy per nucleon...

  • Theoretical covariance matrix

    Theoretical covariance matrix for data from Figure 3

    10.17182/hepdata.138867.v2/t10

    The theoretical (photon flux) covariance matrix of the total coherent photoproduction cross section as a function of photon-nuclear center-of-mass energy...

Version 2 modifications: Added extra material

Loading Data...

Ask a Question


Your question will be emailed to those involved with the submission. Please mention the relevant table.


Please log in to HEPData to send a question.