Studying possible higher twist contributions in the inclusive charged hadron cross sections

TL;DR

This study investigates higher twist contributions in inclusive charged hadron production using xT scaling analysis of ALICE data, comparing standard and HT-inclusive PYTHIA8 models, and finds observed effects are due to isolation cut biases.

Contribution

It introduces a shape analysis method to study higher twist effects in charged hadron production and compares experimental data with models including and excluding HT processes.

Findings

Observed effects are due to isolation cut biases.

No significant evidence of HT enrichment in the data.

Comparison with models helps understand production mechanisms.

Abstract

In the standard pQCD picture particles are produced via the parton jet fragmentation process. However, there are also other production mechanisms like higher twist (HT) processes. A usual example of a HT process is a direct production of an outgoing hadron, where the hadron is produced in the hard subprocess without fragmentation. We study the HT phenomena using a shape analysis (xT scaling) of the inclusive invariant cross sections of charged hadrons, measured by the ALICE collaboration at center-of-mass energies \sqrt{s}=2.76 TeV and 7 TeV. The data is compared to PYTHIA8 event generator and to a phenomenological model for HT. Using PYTHIA8, we explore a possible enhancement of HT phenomena for isolated particles, by comparing the shapes of the isolated distributions to inclusive distributions. The results from the standard PYTHIA8, without HT, is compared to a PYTHIA8 where we had included a HT process. Finally, we found out that the effects observed in the xT spectra originate from kinematic biases posed by the isolation cuts, rather than from an enrichment of the HT hadrons at the observed cross sections. A more detailed data analysis is ongoing.