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.
Jia, S., et al. “Search for ϒ(1S,2S)→Zc+Zc(′)− and e+e−→Zc+Zc(′)− at s=10.52 , 10.58, and 10.867 GeV.” Physical Review D, vol. 97, no. 11, June 2018. Scopus, doi:10.1103/PhysRevD.97.112004. Full Text
Adamczyk, L., et al. “Measurement of the H Λ3 lifetime in Au+Au collisions at the BNL Relativistic Heavy Ion Collider.” Physical Review C, vol. 97, no. 5, May 2018. Scopus, doi:10.1103/PhysRevC.97.054909. Full Text
Adamczyk, L., et al. “Transverse spin-dependent azimuthal correlations of charged pion pairs measured in p↑ + p collisions at s=500 GeV.” Physics Letters, Section B: Nuclear, Elementary Particle and High Energy Physics, vol. 780, May 2018, pp. 332–39. Scopus, doi:10.1016/j.physletb.2018.02.069. Full Text
Nakano, H., et al. “Measurement of time-dependent CP asymmetries in B0 → KS0 ηγ decays.” Physical Review D, vol. 97, no. 9, May 2018. Scopus, doi:10.1103/PhysRevD.97.092003. Full Text
Grygier, J., et al. “Erratum: Search for B →hν ν decays with semileptonic tagging at Belle (Physical Review D (2017) (R) 96 (091101) DOI: 10.1103/PhysRevD.96.091101).” Physical Review D, vol. 97, no. 9, May 2018. Scopus, doi:10.1103/PhysRevD.97.099902. Full Text
Niiyama, M., et al. “Production cross sections of hyperons and charmed baryons from e+e- annihilation near s =10.52 GeV.” Physical Review D, vol. 97, no. 7, Apr. 2018. Scopus, doi:10.1103/PhysRevD.97.072005. Full Text
Masuda, M., et al. “Study of KS0 pair production in single-tag two-photon collisions.” Physical Review D, vol. 97, no. 5, Mar. 2018. Scopus, doi:10.1103/PhysRevD.97.052003. Full Text
Li, Y. B., et al. “Observation of Ξ c(2930) 0 and updated measurement of B-→K-Λc+Λ¯c- at Belle: Belle Collaboration.” European Physical Journal C, vol. 78, no. 3, Mar. 2018. Scopus, doi:10.1140/epjc/s10052-018-5720-5. Full Text
Yelton, J., et al. “Measurement of branching fractions of hadronic decays of the Ω c 0 baryon.” Physical Review D, vol. 97, no. 3, Feb. 2018. Scopus, doi:10.1103/PhysRevD.97.032001. Full Text
AdamczyK, L., et al. “Azimuthal transverse single-spin asymmetries of inclusive jets and charged pions within jets from polarized-proton collisions at s = 500 GeV.” Physical Review D, vol. 97, no. 3, Feb. 2018. Scopus, doi:10.1103/PhysRevD.97.032004. Full Text