A Generalised Area Law for Hadronic String Reinteractions

Abstract

A new model for hadronic string reinteractions based on a generalised area law is presented. The model describes both the hadronic final states in $e^+e^-$ annihilation and the diffractive structure function in deep inelastic scattering. The model also predicts a shift in the W-mass reconstructed from hadronic decays of W-pairs of the order 65 MeV.

Figures (5)

• Figure 1: Illustration of two different string configurations in W-pair production in the lowest order (the strings are indicated with dashed lines).
• Figure 2: The charged multiplicity distribution (a) and the momentum distribution for $\pi^\pm$ (b). The model (solid line) is compared with default Jetset (dashed line) and the model without retuning (dotted line). The data are from the ALEPH and OPAL collaborations respectively with the statistical and systematic errors added in quadrature. The ratio of the model, with (solid) and without (dotted) retuning, to default Jetset is shown below, (b) also shows the ratio of data to default Jetset.
• Figure 3: (a) Illustration of the string effect as explained in the text and (b) the largest rapidity gap distribution. The model (solid line) is compared with default Jetset (dashed line) and in (a) the model without the area suppression factor (dotted line). The ratio of the model and default Jetset is shown below.
• Figure 4: The diffractive structure function obtained with the model applied to Lepto compared to data from the H1 collaboration. The hashed plots corresponds to kinematic points where the mass of the diffractive system $M_X$ is smaller than 2 GeV which is the cut-off in the matrix element.
• Figure 5: The dijet mass spectrum (a) and the charged multiplicity (b) for W-pairs decaying hadronically produced in $e^+e^-$ annihilation at $\sqrt{s}=183$ GeV. The model (solid) is compared with default Pythia (dashed). As indicated, the reconstructed mass is shifted with $\Delta m_W = m_W^{Model} - m_W^{Def} = 65\pm15$ MeV, the mean multiplicity is shifted with $\Delta\!<\!n_{ch}\!> = <\!n_{ch}\!>\!^{Model} - \!<\!n_{ch}\!>\!^{Def} = - 0.4$ whereas the dispersion $D=\sqrt{\!<\!n_{ch}^2\!>\! - \!<\!n_{ch}\!>\!^2}$ is unchanged.