ﻻ يوجد ملخص باللغة العربية
Pions were predicted by H. Yukawa as force carriers of the inter-nucleon forces, and were detected in 1947. Today they are known to be bound states of quarks and anti-quarks of the two lightest flavours. They satisfy Bose statistics, and are the lightest particles of the strong interaction spectrum. Determination of the parameters of the Standard Model, including the masses of the lightest quarks, has only recently reached high precision on the lattice. Pions are also known to be pseudo-Goldstone bosons of spontaneously broken approximate axial-vector symmetries, and a probe of their properties and interactions at high precision tests our knowledge of the strong interactions. While also being a probe of the solution of the strong interactions on the computer, which is known as lattice gauge theory. Despite their long history, there are significant experimental and theoretical challenges in determining their properties at high precision. Examples include the lifetime of the neutral pion, and the status of their masses and decay widths in effective field theories. Pion-pion scattering has been studied for several decades using general methods of field theory such as dispersion relations based on analyticity, unitarity and crossing. Knowledge from these theoretical methods are used to confront high precision experimental data, and to analyze them to extract information on their scattering and phase shift parameters. This knowledge is crucial for estimating the Standard Model contributions to the anomalous magnetic moment of the muon, which is being probed at Fermilab in ongoing experiments. Other sensitive tests include the rare decay of the eta meson into three pions, which represents an isospin violating decay. The present article briefly reviews these important developments.
This is a historical account from my personal perspective of the development over the last few decades of the standard model of particle physics. The model is based on gauge theories, of which the first was quantum electrodynamics, describing the int
We trace the origin of the concept which was named by the High Energy Physics Community The Cabibbo angle
We compute the leading-order evolution of parton distribution functions for all the Standard Model fermions and bosons up to energy scales far above the electroweak scale, where electroweak symmetry is restored. Our results include the 52 PDFs of the
After the LHC Run 1, the standard model (SM) of particle physics has been completed. Yet, despite its successes, the SM has shortcomings vis-`{a}-vis cosmological and other observations. At the same time, while the LHC restarts for Run 2 at 13 TeV, t
We study interactions of unparticles ${cal {U}}$ of dimension $d_{cal {U}}$ due to Georgi with Standard Model (SM) fields through effective operators. The unparticles describe the low energy physics of a non-trivial scale invariant sector. Since unpa