First Measurement of the |t| Dependence of Incoherent J/ψ Photonuclear Production

2024-04-27T12:00:00
UPC PRL

 

 

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PHYSICAL REVIEW LETTERS 132, 162302 (2024)


The first experimental measurement of the incoherent photonuclear production of J/ψ in ultraperipheral heavy-ion collisions is better explained by the presence of subnuclear quantum fluctuations of the gluon field.

The first measurement of the cross-section for incoherent photonuclear production of π½/πœ“ vector mesons as a function of the Mandelstam |𝑑| variable is presented. The measurement was carried out with the ALICE detector at midrapidity, |𝑦|<0.8, using ultraperipheral collisions of Pb nuclei at a center-of-mass energy per nucleon pair of sqrt(𝑠NN)=5.02  TeV. This rapidity interval corresponds to a Bjorken-π‘₯ range (0.3–1.4)Γ—10βˆ’3. Cross sections are given in five |𝑑| intervals in the range 0.04<|𝑑|<1  GeV2 and compared to the predictions by different models. Models that ignore quantum fluctuations of the gluon density in the colliding hadron predict a |𝑑| dependence of the cross-section much steeper than in data. The inclusion of such fluctuations in the same models provides a better description of the data.

 

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