HEPData Search

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Observation of coherent $\phi$(1020) meson photoproduction in ultraperipheral PbPb collisions at $\sqrt{s_\text{NN}}$ = 5.36 TeV

The CMS collaboration Chekhovsky, Vladimir ; Hayrapetyan, Aram ; Makarenko, Vladimir ; et al.

CMS-HIN-24-009, 2025.

Inspire Record 2908607 DOI 10.17182/hepdata.156183

The first observation of coherent $\phi$(1020) meson photoproduction off heavy nuclei is presented using ultraperipheral lead-lead collisions at a center-of-mass energy per nucleon pair of 5.36 TeV. The data were collected by the CMS experiment and correspond to an integrated luminosity of 1.68 $\mu$b$^{-1}$. The $\phi$(1020) meson signals are reconstructed via the K$^+$K$^-$ decay channel. The production cross section is presented as a function of the $\phi$(1020) meson rapidity in the range 0.3 $\lt$$\lvert y\rvert$$\lt$ 1.0, probing gluons that carry a fraction of the nucleon momentum ($x$) around $10^{-4}$. The observed cross section exhibits little dependence on rapidity and is significantly suppressed, by a factor of ${\sim}$5, compared to a baseline model that treats a nucleus as a collection of free nucleons. Theoretical models that incorporate either nuclear shadowing or gluon saturation predict suppression of the $\phi$(1020) meson cross section with only a small dependence on rapidity, but the magnitude of the predicted suppression varies greatly. Models considering only nuclear shadowing effects result in the best agreement with the experimental data. This study establishes a powerful new tool for exploring nuclear effects and nuclear gluonic structure in the small-$x$ regime at a unique energy scale bridging the perturbative and nonperturbative quantum chromodynamics domains.

1 data table

Table 1

The differential coherent $\phi$ photoproduction cross section and the nuclear suppression factor as a function of rapidity.

Study of hadronic final states from double tagged gamma gamma events at LEP.

The ALEPH collaboration Heister, A. ; Schael, S. ; Barate, R. ; et al.

CERN-EP-2003-025, 2003.

Inspire Record 619958 DOI 10.17182/hepdata.49702

The interaction of virtual photons is investigated using double tagged gammagamma events with hadronic final states recorded by the ALEPH experiment at e^+e^- centre-of-mass energies between 188 and 209 GeV. The measured cross section is compared to Monte Carlo models, and to next-to-leading-order QCD and BFKL calculations.

10 data tables

Table 1

Differential cross section as a function of the relative energy of the scattered electrons.

Table 2

Differential cross section as a function of the polar angle THETA of the scattered electrons.

Table 3

Differential cross section as a function of the virtuality Q**2 of the photons.