Easy tests in high energy experiments

Tre fisici teorici hanno fatto un passo in avanti per eliminare alcune ambiguità che derivano dalle complesse formule matematiche che vengono utilizzate per studiare le interazioni tra i quark, le particelle più fondamentali della materia che compongono protoni e neutroni, e i gluoni, le particelle enigmatiche responsabili dell’interazione nucleare forte che lega i quark nei nucleoni. Secondo gli scienziati, semplificando questi calcoli è possibile facilitare, per così dire, il lavoro dei fisici per realizzare previsioni più accurate quando vengono eseguiti gli esperimenti di laboratorio.

The theory describing those interactions is known as quantum chromodynamics (QCD), and is an important component of the Standard Model, the reigning theory of the interactions of subatomic particles. “An important goal in high energy physics is to make predictions that are as precise as possible“, said SLAC theoretical physicist Stan Brodsky. “This makes tests of QCD more rigorous. Most important, if QCD doesn’t pass our experimental tests, it could reveal new physics beyond the Standard Model“. In a paper published in Physical Review Letters, Brodsky and his colleagues, Matin Mojaza of CP3-Origins at the University of Southern Denmark and Xing-Gang Wu of Chongqing University in China, have presented a method that will help theorists to automatically eliminate an important theoretical ambiguity of QCD predictions. Particle theorists attempt to put the quantum realm under a mathematical microscope. However, the world of subatomic particles operates according to very different rules than our familiar everyday world. Quantum uncertainties take hold.

On the scale of quarks and gluons, E=mcis not a slogan on a t-shirt, it’s the law of the land, if there’s a possibility for a particular particle to exist, it, and others, will pop into and out of existence, obscuring what lies under the physicists’ calculational lenses.

These “now you see them, now you don’t” particles, called virtual particles, give rise to infinite terms in quantum calculations, a big problem for theorists, who must remove the uncertainty in their calculations caused by these infinities without introducing new ambiguities. This problem has obscured the precision of the theorists’ mathematical microscope. Brodsky and his colleagues have been developing a method called the Principle of Maximum Conformality (PMC) which can focus the mathematical microscope into the quantum world.

Building on this work, in their new paper, Mojaza, Wu and Brodsky show how a novel generalization of a technique that many theorists employ to remove infinities, called modified minimal subtraction, can be used to identify patterns within the calculations.

This, along with PMC, makes the calculations easier to reduce to a form that can be used to make testable predictions, free of ambiguities, the heart of scientific progress. In addition to adding another tool to the theorists’ toolbox and providing testable predictions to experimenters, their technique has another advantage, said Brodsky: “Since the method is systematic, it can be used as the basis of a computer algorithm“, automating the calculations even further.

SLAC: SLAC Theorist Helps Sharpen Tests of Fundamental Theory in High Energy Experiments

arXiv:A Systematic All-Orders Method to Eliminate Renormalization-Scale and Scheme Ambiguities in PQCD

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