Speakers
Description
The transverse momentum spectrum of low mass Drell-Yan (DY) production at low
center-of-mass energies $\sqrt{s}$ is calculated by applying transverse momentum
dependent (TMD) parton distributions obtained from the Parton Branching (PB)
evolution method, combined with the next-to-leading-order (NLO) calculation of
the hard process in the MCatNLO method. We compare our predictions with
experimental measurements at low DY mass, and find very good agreement. In addition
we use the low mass DY measurements at low $\sqrt{s}$ to determine the width $q_s$
of the intrinsic Gauss distribution of the PB-TMDs at low evolution scales. We find
values close to what has earlier been used in application of PB-TMDs to high-energy
processes at the Large Hadron Collider (LHC) and HERA. We find that low DY mass and
low $q_s$ 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 and LHC energies the contribution from soft
gluons in the region of $p_t/m_{DY}\sim 1$ is small.
