Azimuthal Asymmetries in Hadronic Final States at HERA

Abstract

The distribution of hadrons produced in deeply inelastic electron-proton collisions depends on the azimuthal angle between lepton scattering plane and hadron production plane in the photon-proton centre-of-mass frame. In addition to the well known up-down asymmetry induced by the azimuthal dependence of the Born level subprocess, there is also a non-vanishing left-right asymmetry, provided the incoming electron is polarized. This asymmetry is time-reversal-odd and induced by absorptive corrections to the Born level process. We investigate the numerical magnitude of azimuthal asymmetries in semi-inclusive hadron production at HERA with particular emphasis on a possible determination of the time-reversal-odd asymmetry.

Figures (7)

• Figure 1: The asymmetry $\langle \cos \phi\rangle(P_T)$ in neutral current charged hadron production. Solid line: $0.005 < z < 0.01$, dashed line: $0.01 < z < 0.05$, dotted line: $0.05< z < 0.1$, short dot-dashed line: $0.1<z<0.3$ and long dot-dashed line $0.3<z<0.9$.
• Figure 2: The asymmetry $\langle \cos (2\phi)\rangle(P_T)$ in neutral current charged hadron production. Curves as in Fig. \ref{['fig:nccos']}.
• Figure 3: The $T$-odd asymmetry $\langle \sin \phi\rangle(P_T)$ in neutral current charged hadron production. Curves as in Fig. \ref{['fig:nccos']}.
• Figure 4: The asymmetry $\langle \cos \phi\rangle(P_T)$ in charged current $(e^-)$ charged hadron production. Curves as in Fig. \ref{['fig:nccos']}.
• Figure 5: The asymmetry $\langle \cos (2\phi)\rangle(P_T)$ in charged current $(e^-)$ charged hadron production. Curves as in Fig. \ref{['fig:nccos']}.