The Boer-Mulders and Cahn effects: azimuthal modulations in the spin-independent SIDIS cross section at Hermes

The coφh and cos 2φh modulations of the spin independent semi-inclusive deep inelastic scattering cross section were measured at Hermes. These modulations are sensitive to the polarization and transverse motion of quarks within the nucleon. The Cahn effect, which contributes at subleading twist (twist-3) to cosφh and twist-4 to cos2φh, is sensitive to transverse motion of quarks. The Boer-Mulders effect, which contributes at subleading twist to cosφh and leading twist to cos2φh, requires non-zero transverse quark motion and is sensitive to quark polarization, effectively measuring the quark spin-orbit correlation. These modulations were measured in a fully differential way, as a function of x, y, z, and Ph⊥ for positive and negative pions, kaons, and unidentified-hadrons produced from hydrogen and deuterium targets at Hermes. This is the the most complete measurement to date, for the first time granting access to the flavor dependent distribution and fragmentation functions that generate these moments. These measurement would not have been possible without an improved hadron-type identification algorithm for the Ring Imaging Cherenkov (RICH) detector. The EVT event-level algorithm is presented and now is the primary method used at Hermes

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2010

Author dc:creator

• Lamb, Rebecca M.

Contributors dc:contributor

• Makins, Naomi C.R.
• Grosse Perdekamp, Matthias
• Willenbrock, Scott S.
• Stack, John D.

• Cahn effect
• Boer-Mulders distribution function
• azimuthal modulations
• semi-inclusive deep inelastic scattering
• intrinsic transverse momentum
• spin

Statement dc:rights

• Copyright 2010 Rebecca M. Lamb

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/16759

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/16759