Probing the X(3700) through two-photon D D̅ production in ultraperipheral collisions and at the EIC
Abstract
We investigate whether photon-induced production in ultraperipheral heavy-ion collisions and at the EIC can provide a new environment to search for the scalar D D̅ molecular candidate usually denoted as X(3700). We calculate the tree-level amplitudes for γγ→ D+ D- and γγ→ D0 D0̅, dress the outgoing pair with a coupled-channel Bethe-Salpeter interaction in the (D+ D- , D0 D0̅) basis, and convolute the resulting subprocess cross sections with equivalent-photon spectra. In the adopted two-channel scenario the analytic continuation of the T-matrix gives a bound state at MX=3.7162~GeV, which is below the D0 D0̅ threshold. As a consequence of this, the observed signal in the continuum is not simply an isolated narrow peak, and a characteristic near-threshold line-shape distortion is produced: around 3.70 ≤ W ≤ 3.85~GeV the integrated dressed-to-bare ratios are $(13.71,0.35)$ in Pb-Pb UPCs and $(13.74,0.35)$ in e-Au collisions for (D+D-,D0 D0̅). Using the BABAR-fitted central normalization Kdressed=0.382, the corresponding dressed cross sections are (24.6,14.6) μb in Pb-Pb UPCs and (2.41,1.43) nb at the EIC. The charged-to-neutral ratios are directly accessible observables, whereas the dressed-to-bare ratios provide theoretical diagnostics of the final-state interaction. The near-threshold features are controlled by the common γγ→ DD̅ dynamics and are rather independent of the external photon source.
Versions
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BibTeX
@misc{sobrinho2026probing,
title = {{Probing the X(3700) through two-photon $D \barD$ production in ultraperipheral collisions and at the EIC}},
author = {F. C. Sobrinho and F. S. Navarra and K. P. Khemchandani and A. Martínez Torres},
howpublished = {arXiv},
year = {2026},
month = jul,
doi = {10.48550/arxiv.2607.12224},
eprint = {2607.12224},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.12224},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Probing the X(3700) through two-photon D D̅ production in ultraperipheral collisions and at the EIC
AU - F. C. Sobrinho
AU - F. S. Navarra
AU - K. P. Khemchandani
AU - A. Martínez Torres
PY - 2026
DA - 2026/07/13
PB - arXiv
DO - 10.48550/arxiv.2607.12224
UR - https://arxiv.org/abs/2607.12224
AB - We investigate whether photon-induced production in ultraperipheral heavy-ion collisions and at the EIC can provide a new environment to search for the scalar D D̅ molecular candidate usually denoted as X(3700). We calculate the tree-level amplitudes for γγ→ D^+ D^- and γγ→ D^0 D^0̅, dress the outgoing pair with a coupled-channel Bethe-Salpeter interaction in the (D^+ D^- , D^0 D^0̅) basis, and convolute the resulting subprocess cross sections with equivalent-photon spectra. In the adopted two-channel scenario the analytic continuation of the T-matrix gives a bound state at M_X=3.7162~GeV, which is below the D^0 D^0̅ threshold. As a consequence of this, the observed signal in the continuum is not simply an isolated narrow peak, and a characteristic near-threshold line-shape distortion is produced: around 3.70 ≤ W ≤ 3.85~GeV the integrated dressed-to-bare ratios are $(13.71,0.35)$ in Pb-Pb UPCs and $(13.74,0.35)$ in e-Au collisions for (D^+D^-,D^0 D^0̅). Using the BABAR-fitted central normalization K_dressed=0.382, the corresponding dressed cross sections are (24.6,14.6) μb in Pb-Pb UPCs and (2.41,1.43) nb at the EIC. The charged-to-neutral ratios are directly accessible observables, whereas the dressed-to-bare ratios provide theoretical diagnostics of the final-state interaction. The near-threshold features are controlled by the common γγ→ DD̅ dynamics and are rather independent of the external photon source.
ER -