Anselm G. Vossen
Assistant Professor of Physics
In Quantum Chromodynamics (QCD), the theory of the strong interactions, the nucleon emerges as a strongly interacting, relativistic bound state of almost massless quarks and gluons.
Fifty years of experimental investigations into the nucleon's internal structure have provided remarkable insight into quark and gluon dynamics. However, many outstanding questions remain.
For example, the origin of the spin of the proton is still eludes us and many other properties of the nucleon cannot yet be derived from first order calculations. Even fundamental aspects like a quantitative understanding of the origin of the mass of the nuclei (and thus most of the visible mass in the universe) as well as the confinement of quarks into hadrons remain outside our current understanding.
My research approaches these questions from two sides. At the newly upgraded Jefferson Lab facility, we use electron proton scattering data to map out the 3D dynamics of the nucleon. We are in particular interested in polarized probes that are sensitive to spin-orbit coupling in the proton wavefunction.
And at the newly constructed Belle II experiment, we use electron-positron annihilation data, to study how hadrons emergy from initial quarks. We are in particular interested how the quantum numbers of the inital quark, like spin, are expressed in the final state hadrons.
My group also works on precision tests of the flavor sector of the standard model at the intensity frontier. To this end we study the properties of B meson detected with the Belle II experiment.
Tamponi, U., et al. “First Observation of the Hadronic Transition ϒ(4S)→ηh(b)(1P) and New Measurement of the h(b)(1P) and η(b)(1S) Parameters.” Physical Review Letters, vol. 115, no. 14, Oct. 2015, p. 142001. Epmc, doi:10.1103/physrevlett.115.142001. Full Text
Adare, A., et al. “Measurements of Elliptic and Triangular Flow in High-Multiplicity 3He+Au Collisions at √(s(NN))=200 GeV.” Physical Review Letters, vol. 115, no. 14, Oct. 2015, p. 142301. Epmc, doi:10.1103/physrevlett.115.142301. Full Text
Kronenbitter, B., et al. “Measurement of the branching fraction of B+ →τ+ντ decays with the semileptonic tagging method.” Physical Review D Particles, Fields, Gravitation and Cosmology, vol. 92, no. 5, Sept. 2015. Scopus, doi:10.1103/PhysRevD.92.051102. Full Text
Choi, S. K., et al. “Erratum: Publisher's Note: Measurements of B → D ¯ Ds0∗+ (2317) decay rates and a search for isospin partners of the Ds0∗+ (2317) (Physical Review D - Particles, Fields, Gravitation and Cosmology (2015) 91 (092011)).” Physical Review D Particles, Fields, Gravitation and Cosmology, vol. 92, no. 3, Aug. 2015. Scopus, doi:10.1103/PhysRevD.92.039905. Full Text
Adamczyk, L., et al. “Precision Measurement of the Longitudinal Double-Spin Asymmetry for Inclusive Jet Production in Polarized Proton Collisions at sqrt[s]=200 GeV.” Physical Review Letters, vol. 115, no. 9, Aug. 2015, p. 092002. Epmc, doi:10.1103/physrevlett.115.092002. Full Text
Adamczyk, L., et al. “Measurements of dielectron production in Au + Au collisions at sNN =200 GeV from the STAR experiment.” Physical Review C Nuclear Physics, vol. 92, no. 2, Aug. 2015. Scopus, doi:10.1103/PhysRevC.92.024912. Full Text
Adamczyk, L., et al. “Energy dependence of Kπ, pπ, and Kp fluctuations in Au + Au collisions from sNN =7.7 to 200 GeV ENERGY DEPENDENCE of Kπ, pπ, and Kp ... L. ADAMCZYK et al.” Physical Review C Nuclear Physics, vol. 92, no. 2, Aug. 2015. Scopus, doi:10.1103/PhysRevC.92.021901. Full Text
Han, Y. L., et al. “Measurement of e+e- →γχcJ via initial state radiation at Belle.” Physical Review D Particles, Fields, Gravitation and Cosmology, vol. 92, no. 1, July 2015. Scopus, doi:10.1103/PhysRevD.92.012011. Full Text
Adamczyk, L., et al. “Beam-energy-dependent two-pion interferometry and the freeze-out eccentricity of pions measured in heavy ion collisions at the STAR detector.” Physical Review C Nuclear Physics, vol. 92, no. 1, July 2015. Scopus, doi:10.1103/PhysRevC.92.014904. Full Text