# Some properties of the pT regions observed at the LHC energies

## TL;DR

This paper analyzes the properties of transverse momentum (pT) regions observed at LHC energies, revealing two distinct groups with different energy dependencies, and suggests a connection to string fragmentation dynamics in particle production.

## Contribution

It identifies two groups of pT regions with distinct characteristics and proposes a link to string fragmentation processes, providing new insights into particle production mechanisms at high energies.

## Key findings

- Two pT region groups with different energy dependencies.
- Ratios of eta-mesons to pions lengths approximate their mass ratios.
- Evidence supporting string fragmentation dynamics in hadronization.

## Abstract

The inclusive spectra of the charged particles, $\pi^0$- and $\eta$-mesons produced in the pp collisions at LHC energies were analyzed . The data revealed several $p_T$ regions, which could be characterized by the length of the regions L and two free fitting parameters a and b. The study of the characteristics of the regions shown that the regions are divided into two groups. The values of the L and b for the first group don't depend on colliding energy and the properties of the particles (though the values of a increase linearly with energy), however, the second group regions' characteristics show strong dependencies. We found that the ratio of the eta-mesons to neutral pions lengths is approximately equal to the ratio of their masses. Assuming that the L values are directly proportional to the string tension, this result could be the evidence of parton string fragmentation dynamics, since in string theory the masses of elementary particles and their energy are defined by the intensity of string vibration . The increasing lengths for the eta-mesons' regions are accompanied with increasing values of b parameter. Taking into account that $Q^2\sim 1/b^2$ we have concluded that the eta-mesons were produced at lesser values of $\alpha _S$ compare to neutral pions. The results show that the lengths of the first group of regions are ~3-5 times greater than the lengths of neighboring lower pT regions. The second group's lengths are ~ 2 times greater than the lengths of neighboring lower pT region. In the framework of string fragmentation and hadronization dynamics, it could mean that the group I is produced through string decay into ~ 3-5 strings, whereas group II is produced through decay into ~2 strings. The existence of 2 groups of regions could hint to two types of strings responsible for the observed groups.

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Source: https://tomesphere.com/paper/1812.07468