Researchers simulate important structural elements of the pion

Simone Ulmer works at the Swiss National Supercomputing Centre.

QCD is a research field that deals with the structure and composition of matter. One of the four fundamental forces of physics can be described in hadrons with the help of QCD. The particles are held together by a strong interaction. The lesser-known pion is also a hadron and is the driving particles behind the strong interaction.

The pion is fleeting in high-energy experiments, for example in the scattering of protons or the collision of protons. The structure of the pion has been difficult to study so far. Understanding high-energy physics depends on theoretical descriptions. Due to the strength of the forces being studied and the small amount of particles, computer simulations are the only way to achieve theoretical descriptions.

The description for the momentum fractions of quarks and gluons in the pion was provided by the researchers from Switzerland, Germany and Cyprus. The study was the result of a long-term research collaboration.

A sea of particles.

The parton distribution function can be used to determine a quark with a certain fraction in the pion.

To be able to determine the real momentum fractions of the quarks and gluons in the pion, the researchers must calculate an entire sea of particles and how they interact with each other. The quark building blocks of the pion, known as valence quarks, the virtual fractions of short-lived quarks, and the so-called unconnected contributions, are found in this vast sea.

The path to the results of the calculations of the sea of particles was long and difficult. The researchers took into account the gluons and four types of quarks that make up the pion and other hadrons in the development of ensemble of so-called gluon configurations. There are two different quarks flavors inions. There are six different quark flavors. To complete the picture, we need to include all the contributions in the calculations and simulations.

We can use the simulation to calculate the properties of other particles composed of quarks from the experiment and compare them, because each particle has its own physics. This allows us to understand the experiments and learn something about the particles.

There were no hidden shares.

The high computer performance of the 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 888-349-8884 The results obtained were correct because of the fact that the determined momentum fractions of the four quarks and the gluon added up to a value.

The physical values of the quark mass were used in the calculations. This has only been possible since a few years ago, as calculations with real mass are very complex and demanding. The researchers had to determine a statistically significant signal for the unconnected contributions of the sea quarks and gluons. It would not have been possible to detect a clear signal because of the quantum effects between the quarks and the gluons. The researchers were able to reduce both the statistical and systematic errors in their calculations because of the improved computer performance, better algorithms and real values of the quark mass.

The researchers used a certain lattice spacing. This mistake is automatic because we are on a grid and not in a continuum. The grid spacing needs to approach zero to be able to reach the continuum. The calculations become more complex when the distance is smaller. Even smaller grid spacings have been calculated by the researchers. The results of new experiments and the particles involved in them will be better understood once the findings are available.

More information: Constantia Alexandrou et al, Quark and Gluon Momentum Fractions in the Pion from Nf=2+1+1 Lattice QCD, Physical Review Letters (2021). DOI: 10.1103/PhysRevLett.127.252001 Journal information: Physical Review Letters Provided by Swiss National Supercomputing Centre Citation: Researchers simulate important structural elements of the pion (2022, February 25) retrieved 25 February 2022 from https://phys.org/news/2022-02-simulate-important-elements-pion.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.