Exclusive emissions of rho-mesons and the unintegrated gluon distribution
Andrèe Dafne Bolognino, Francesco Giovanni Celiberto, Dmitry Yu. Ivanov, Alessandro Papa
Abstract
Exclusive emissions of vector mesons in forward directions of rapidity offer us a faultless chance to probe the proton structure at small x <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>x</mml:mi></mml:math> . A high-energy factorization formula is established within BFKL, given as the convolution of an impact factor depicting the forward-meson emission and of an unintegrated gluon distribution (UGD) driving the gluon evolution at small x <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>x</mml:mi></mml:math> . As a nonperturbative quantity, the UGD is not well known and several models for it exist. We present recent progresses on the study of the exclusive forward \rho <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>ρ</mml:mi></mml:math> -meson leptoproduction at HERA and EIC energies, showing how osbervables sensitive to different polarization states of the \rho <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>ρ</mml:mi></mml:math> -particle act as discriminators for the existing UGD models.