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[PAST EVENT] Physics Colloquium - Vossen
March 4, 2016
4pm - 5pm
Abstract:
The discovery of transverse spin effects in e+e- jets in Belle has handed us a unique quark polarimeter that connects microscopic quark spin observables in high energy collisions with measurable angular distributions of final state hadrons reconstructed in the detector. The Belle discovery makes it possible for the first time, to extract the transverse spin distributions of quarks inside the proton from transverse spin observables measured in polarized proton-proton collisions and in lepton-nucleon scattering. The net transverse polarization, the so-called tensor charge, is a fundamental property of the proton and can be computed ab initio QCD using lattice techniques. The theoretical effort aims at describing QCD at the nucleon mass scale and will shed light on the dynamics that leads to the creation of most of the visible mass in the Universe. The tensor charge also can be used for constraining coupling constants for certain extension of the standard model. This colloquium will cover the measurement of quark spin effects in e+e- annihilation in Belle and spin asymmetry measurements in polarized p+p collisions with the STAR detector at the Relativistic Heavy Ion Collider. Together, these results are used to extract the transverse polarization of quarks in the proton. Finally, Belle is currently being upgraded to Belle II to take advantage of an increase of the delivered instantaneous luminosity by a factor of about 40. The status of the upgrade and future possibilities it enables in conjunction with high precision data on transverse spin asymmetries in lepton-nucleon scattering to be collected at the JLab12 experiments will be discussed.
The discovery of transverse spin effects in e+e- jets in Belle has handed us a unique quark polarimeter that connects microscopic quark spin observables in high energy collisions with measurable angular distributions of final state hadrons reconstructed in the detector. The Belle discovery makes it possible for the first time, to extract the transverse spin distributions of quarks inside the proton from transverse spin observables measured in polarized proton-proton collisions and in lepton-nucleon scattering. The net transverse polarization, the so-called tensor charge, is a fundamental property of the proton and can be computed ab initio QCD using lattice techniques. The theoretical effort aims at describing QCD at the nucleon mass scale and will shed light on the dynamics that leads to the creation of most of the visible mass in the Universe. The tensor charge also can be used for constraining coupling constants for certain extension of the standard model. This colloquium will cover the measurement of quark spin effects in e+e- annihilation in Belle and spin asymmetry measurements in polarized p+p collisions with the STAR detector at the Relativistic Heavy Ion Collider. Together, these results are used to extract the transverse polarization of quarks in the proton. Finally, Belle is currently being upgraded to Belle II to take advantage of an increase of the delivered instantaneous luminosity by a factor of about 40. The status of the upgrade and future possibilities it enables in conjunction with high precision data on transverse spin asymmetries in lepton-nucleon scattering to be collected at the JLab12 experiments will be discussed.