Probing transverse-momentum dependent evolution with groomed jets

• Main Authors: Yiannis Makris, Duff Neill, Varun Vaidya
• Format: Article
• Language: English
• Published: SpringerOpen 2018-07-01
• Series: Journal of High Energy Physics
• Subjects: Jets; QCD Phenomenology
• Online Access: http://link.springer.com/article/10.1007/JHEP07(2018)167

Abstract We propose an observable which involves measuring the properties (transverse momentum p h⊥ and energy fraction z h ) of an identified hadron inside a groomed jet. The jet is identified with an anti-kT/CA algorithm and is groomed by implementing the modified mass drop procedure with an energy cut-off parameter, z cut. The transverse momentum of the hadron inside the jet is measured with respect to the groomed jet axis. We obtain a factorization theorem in the framework of Soft Collinear Effective Theory (SCET), to define a Transverse Momentum Dependent Fragmenting Jet Function (TMDFJF). The TMDFJF is factorized into collinear and collinear soft modes by matching onto SCET+. We resum large logarithms in E J /p h⊥, where E J is the ungroomed jet energy, to NLL accuracy and apply this formalism for computing the shape of the p h⊥ distribution of a pion produced in an e + + e − collision. We observe that the introduction of grooming makes this observable insensitive to non-global logarithms and particularly sensitive to non-perturbative physics of the transverse momentum dependent evolution at low values of p h⊥, which can be probed in the variation of the cut-off parameter, z cut, of the groomer. We discuss how this observable can be used to distinguish between non-perturbative models that describe universal TMD evolution and provide a window into the three dimensional structure of hadrons.