Drell-Yan production at NLO in the Parton Branching method at low and high DY masses

It has been observed that measurements of low-mass Drell-Yan (DY) transverse momentum spectra at low center-of-mass energies $\sqrt{s}$ are not well described by perturbative QCD calculations in collinear factorization in the region where transverse momenta are comparable with the DY mass. This issue can be examined with the Parton Branching (PB) method combining next-to-leading-order (NLO) calculations of the hard process with the evolution of transverse momentum dependent (TMD) parton distribution. The predictions are compared with measurements of low mass DY production, and they are in very good agreement. Predictions have also been compared with the measurement of DY production at high energies at the LHC. We find that at low-mass DY and low $\sqrt{s}$ even in the region of $p_{T}/m_{DY}\sim 1$ the contribution of multiple soft gluon emissions (included in the PB-TMDs) is essential to describe the measurements, while at larger masses ($m_{DY}\sim m_{Z}$) and LHC energies the contribution from soft gluons in the region of $p_{T}/m_{DY}\sim 1$ is small.