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arXiv · 2507.06207

Dilepton angular distributions in the color-dipole $S$-matrix framework

Yan B. Bandeira·Victor P. Goncalves·Wolfgang Schäfer
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Abstract

The dilepton production at forward rapidities in hadronic collisions at the LHC energies is considered and the helicity density matrix elements of gauge bosons that enter the Drell--Yan angular coefficients associated with the gauge boson decay ($G = \gamma^*, Z^0, W$) are derived using the color-dipole $S$ - matrix framework. We show results for $pp$ collisions at $\sqrt{s} = 14$ TeV for the nonvanishing helicity density matrix elements in the rapidity range of $2.0 \le y \le 4.0$ of the gauge boson. We consider different models for the proton unintegrated gluon distributions, among others a solution of the Balitsky--Kovchegov equation. We compare the associated predictions with those obtained disregarding the non-linear term in the evolution equation. In addition, the Lam--Tung relation is discussed.

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Yan B. Bandeira, Victor P. Goncalves, Wolfgang Schäfer. 2025-07-08. Dilepton angular distributions in the color-dipole $S$-matrix framework. https://arxiv.org/abs/2507.06207

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