nucl-th digest · Jul 31, 2024

The Proton Charge Radius from Dimuon Photoproduction off the Proton

We investigate the feasibility of measuring the proton charge radius through dimuon photoproduction off a proton target. Our findings indicate that the Bethe-Heitler mechanism, which dominates at small momentum transfers, allows for an extraction of the proton electromagnetic form factors in the extremely low

Q^{2}

region below

1 0^{- 3}

GeV

^{2}

in the spacelike region, when the incident photon beam energy exceeds several hundred MeV. The optimal kinematical region and a sensitivity study of the proton charge radius from dimuon photoproduction are presented. Such a measurement is expected to provide an alternative to the elastic muon-proton scattering measurements such as MUSE at PSI and AMBER at CERN.

Comments:: 6 pages, 5 figures. The version to be published in PLB
Subjects:: High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:: 2407.20375 [pdf]

PLB(2024)·2 citations

[Submitted on 30 Jul 2024] (cross-list from hep-ph)

System size dependence of energy loss and correlations of heavy mesons at LHC energies

Jiaxing Zhao🇫🇷 · Joerg Aichelin🇫🇷 · Pol Bernard Gossiaux🇫🇷 · Klaus Werner🇫🇷

We study the system size dependence of heavy quark (HQ) observables at a center of mass energy of $s_{NN} = 5.02$ TeV to explore whether it can provide further constraints on the physical processes which are involved: energy loss of HQs in the quark gluon plasma (QGP), hadronization and hadronic rescattering. We use the EPOS4HQ approach to study p-p and 0-10\% central O-O, Ar-Ar, Kr-Kr and Pb-Pb reactions and investigate in detail the momentum change of heavy quarks from creation until their detection as part of a hadron as well as the enhancement of heavy baryon production at low $p_{T}$ . We investigate furthermore the origin and the system size dependence of the azimuthal correlations between the heavy quark $Q$ and the heavy antiquark $Q ˉ$ and how one can bypass the problem that correlations are washed out due to the combinatorial background. We conclude that a systematic study of the system size dependence of the momentum loss allows to separate the momentum loss due to the passage through the QGP from the momentum change due to hadronization and the $Q Q ˉ$ correlations allow to gain inside into the different pQCD processes in which the heavy quarks are created.

Subjects:: High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:: 2407.20919 [pdf]

PRC(2025)·12 citations

Wednesday·July 31, 2024

The Proton Charge Radius from Dimuon Photoproduction off the Proton

System size dependence of energy loss and correlations of heavy mesons at LHC energies

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