Proton Neutron


The article Plot of the week – quark compositeness is nowhere near posted in Tommaso Dorigo’s blog is wrong. After reading this post, please take a look at the post BIASED NUCLEON STRUCTURE.

As I explain in the paper The Higgs Boson and Quark Compositeness (presented at Moriond 2014), and in its presentation, and in the paper Weak decays of hadrons reveal compositeness of quarks, what CMS and ATLAS have found is that prequarks are pointlike, actually, the three outermost prequarks (in the proton) as the three innermost prequarks form a small hard core. This hard core has been observed in many energy ranges and has recently been confirmed by TOTEM at 7 and 8 TeV. Please, see the important references on the subject in the presentation at Moriond 2014.

In order to see prequarks it is enough to take a look at the electric charge distributions in the nucleons (shown below) found by R. Hofstadter (Nobel Prize of 1961 together with R. L. Mössbauer) in the 1950s at SLAC (Rev. Modern Phys. Vol. 28, 214, 1956) and R. Wilson (then at Cornell University) in the early 1960s (Electric Structure of Nucleons) which cannot be produced by the three pointlike quarks uud and udd, according to QCD. A word of caution here: everybody knows that the quark model is very successful, but it cannot describe Hofstadter results in terms of pointlike quarks. We clearly see that both nucleons have a common core and that both of them have two layers of constituents. Therefore, the great physicists R. Hofstadter and R. Wilson found out prequarks before the discovery of quarks. In the paper  The Higgs Boson and Quark Compositeness I show the reason of the success of the quark model: the hard core is small and around it there are 3 prequarks that are looser (we also see this in Hofstadter results because the outer layer varies from about 0.3 fm up to about 1.75 fm) than the innermost prequarks. These outer prequarks are confused with the so-called valence quarks which are almost massless. But in hadronization processes we just plug in the masses of constituent quarks which are, actually, the true quarks. And when we probe the proton with electrons through very deep inelastic scattering (that is, electrons with very small Compton wavelength) we see the three prequarks of the hard core and, again we confuse them with the so-called valence quarks. That is also the reason why it is very hard to pinpoint prequarks. Therefore, prequarks, constituent quarks and the so-called valence quarks are completely entangled. But the quantum numbers don’t lie and through them we clearly see the whole picture. For example, take a look at the post All Higgs decays linked to a new quantum number.