Sensitivity of the photon-induced processes to the proton charge radius
Abstract
We study the exclusive production of dileptons in proton--proton collisions as a probe of the proton charge-radius scale. Using a dipole form factor model, we compare the conventional choice of Λ2=0.71~GeV2 with PDG test scenarios corresponding to rp=0.8751 ± 0.0061~fm and rp=0.84087 ± 0.00039~fm, representative of the historical large-radius from CODATA and smaller-radius from muonic-hydrogen determinations, respectively. The sensitivity is greatest at large dilepton invariant masses and forward/backward rapidity. Fitting to the current ATLAS and CMS data within the adopted model gives Λ2 = 0.465 ± 0.056 GeV2, corresponding to an effective radius rp = 1.002 ± 0.038 fm, which indicates non-trivial sensitivity on the proton radius scale, but is not yet a definitive solution to the proton radius puzzle. While this result depends on the theoretical model used in the calculation, it shows that exclusive dilepton production at LHC can provide complementary model-dependent information on the proton electromagnetic forms factor.
Related
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BibTeX
@misc{krishna2026sensitivity,
title = {{Sensitivity of the photon-induced processes to the proton charge radius}},
author = {Nikhil Krishna and Mariola Klusek-Gawenda and Rafal Staszewski},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.19604},
eprint = {2606.19604},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.19604},
note = {CC0},
}
RIS
TY - UNPB
TI - Sensitivity of the photon-induced processes to the proton charge radius
AU - Nikhil Krishna
AU - Mariola Klusek-Gawenda
AU - Rafal Staszewski
PY - 2026
DA - 2026/09/15
PB - arXiv
DO - 10.48550/arxiv.2606.19604
UR - https://arxiv.org/abs/2606.19604
AB - We study the exclusive production of dileptons in proton--proton collisions as a probe of the proton charge-radius scale. Using a dipole form factor model, we compare the conventional choice of Λ^2=0.71~GeV^2 with PDG test scenarios corresponding to r_p=0.8751 ± 0.0061~fm and r_p=0.84087 ± 0.00039~fm, representative of the historical large-radius from CODATA and smaller-radius from muonic-hydrogen determinations, respectively. The sensitivity is greatest at large dilepton invariant masses and forward/backward rapidity. Fitting to the current ATLAS and CMS data within the adopted model gives Λ^2 = 0.465 ± 0.056 GeV^2, corresponding to an effective radius r_p = 1.002 ± 0.038 fm, which indicates non-trivial sensitivity on the proton radius scale, but is not yet a definitive solution to the proton radius puzzle. While this result depends on the theoretical model used in the calculation, it shows that exclusive dilepton production at LHC can provide complementary model-dependent information on the proton electromagnetic forms factor.
ER -