Upper Limit on the Prompt Muon Flux Derived from the LVD Underground Experiment

TL;DR

This study analyzes muon events from the LVD underground experiment to establish an upper limit on prompt muon flux, providing constraints on cosmic ray muon models and charm production mechanisms.

Contribution

It offers the first comprehensive measurement of muon flux parameters and sets an upper limit on prompt muon flux based on extensive underground data.

Findings

Measured muon intensity distribution and derived spectral parameters.

Established an upper limit on prompt muon flux, R_c < 2.0 x 10^-3.

Results support charm production models based on QGSM and dual parton model.

Abstract

We present the analysis of the muon events with all muon multiplicities collected during 21804 hours of operation of the first LVD tower. The measured depth-angular distribution of muon intensities has been used to obtain the normalization factor, A, the power index, gamma, of the primary all-nucleon spectrum and the ratio, R_c, of prompt muon flux to that of pi-mesons - the main parameters which determine the spectrum of cosmic ray muons at the sea level. The value of gamma = 2.77 +/- 0.05 (68% C.L.) and R_c < 2.0 x 10^-3 (95% C.L.) have been obtained. The upper limit to the prompt muon flux favours the models of charm production based on QGSM and the dual parton model.