The following comments on the Brightsen Nucleon Cluster Model were received from the web site [ MadSci Network: Physics ] in answer to a question submitted by the webmaster of this site about the possible binding of matter protons [P] to antimatter neutrons [N] to form deuterium of the type [Pmatter-Nantimatter]. See "unmatter" concept of Florentin Smarandache in the June 5, 2005 posting below for the motivation for this question.
Question: Re: can matter proton bind to antimatter neutron to form deuteron ?
Date: Tue Jun 7 09:47:49 2005
Posted By: Benn Tannenbaum, Senior Program Associate
Area of science: Physics
ID: 1117994649.Ph
Message:
I'm afraid that the Brightsen model has been disproved. We now know that protons and neutrons are made of up and down quarks-- two up and one down for the proton and two down and one up for the neutron.
Webmaster update: June 30, 2005. In fact, what we know (as of June, 2005) is that the above statement by Dr. Tannenbaum is incomplete. Research as viewed at this link indicates that the internal structure of the proton is much more complex than three simple quarks (uud). Within the "proton sea" are known to exist so-called virtual mesons (matter quarks bound to antimatter quarks), and the strange quark has recently been verified as being present within the internal structure of the proton (see this link to Science Daily)
This was realized in the 1960s and eventually codified in Quantum Chromodynamics, part of the Standard Model. Gross, Politzer and Wilczek won the 2004 Nobel Prize in Physics for their discovery of asymptotic freedom in the strong force (see http://nobelprize.org/physics/laureates/2004/index.html for more details) which binds quarks together to form protons and neutrons. Because of this knowledge, we know that a proton is made of two up and a down quark and an anti-matter neutron is made of two anti-down quarks and an anti-up quark. Instead of a neutron, what you'd likely get is three pions: two (up/anti-down) pions and one (down/anti-up) pion, or (up/anti-up), (up/anti-down), and (down/anti-up).
Webmaster update: June 30, 2005. The above statement by Dr. Tennenbaum implies that in all cases Quantum chromodynamics (QCD) predicts that matter and antimatter nucleons cannot form bound clusters. However, as read at this link, it has been shown experimentally that a proton and antiproton can form "protonium", with the following quark structure (uud) + (u^u^d^). The quark structure for proton + antineutron is (uud) + (d^d^u^). Thus if the quark structure of "protonium" can bind to form a matter + antimatter nucleon pair, then [P + N^] interactions may also be possible.
So... why would this happen rather than what you predicted? My reading of the Brightsen nuclear cluster model is that it assumes that protons and neutrons are point particles, or at least ones that are indivisible. We know that not to be true-- 40+ years of experiment and theory have convinced us that protons and neutrons are composed of quarks.
Webmaster update: June 30, 2005. The above comments represent a misunderstanding of the Brightsen Model. As discussed below, Mr. Brightsen did recognize quarks as possible sub-structure particles of nucleons.
Further, we also know that protons and neutrons inside a nucleus do not behave as point particles but rather as bags of quarks.
Webmaster update: June 30, 2005. The Brightsen Model does not recognize proton and neutrons as "point particles" for the simple reason that the model predicts that free protons and free neutrons (unbound) do not exist within nuclear shells of isotopes. This is not to say that the Brightsen MOdel predicts that free [P] and [N] do not exist somewhere, they just do not exist within the bounds of isotopes. The Brightsen Model recognizes "clusters of protons and neutrons" as the basic macroscopic building blocks of isotopes. This seemingly radical view is in complete agreement with the various "bag models" of quark structure. According to the Brightsen Model, the "bag of quarks" is not confined to the volume of individual nucleons, but is confined within the boundaries of various "cluster of nucleons" such as {NP], [PNP], [NPN], [NN], [PP].
By shooting probes at nuclei (such as electrons, protons, or neutrons) we have learned that we can get scattering from either individual quarks (shooting softly) or protons or neutrons (shooting hard). This, in turn, tells us that the quarks inside the nucleus are not confined to the proton or neutron but rather spread out across the nucleus. This is what prevents the reaction you describe from occuring.
I hope this helps! MadSci Network: Physics
(Comments and experimental facts on this question are welcome)
In his answer, Dr. Tannenbaum does not include "color" quark dynamics, which may allow for the formation of a strange type of deuterium with mixture of matter and antimatter nucleons and quarks. According to QCD with color, up and down quarks come in three color forms, red, blue, green, and a baryon must include one of each to form a "white" structure. Thus, for example, reducing the nucleon [P+N^] macroscopic cluster to quark dynamics, and including "color", will yield the following type of deuterium structure: [(r-u+b-u+g-d) + (g-u^+b-d^+r-d^)], which suggests the possibility that a bound [PN^] nucleon resonance can result, given that no identicle matter-antimatter quark color pairs are present in the final structure.
In addition, Dr. Tennenbaum makes what turns out to be a false assumption in his final paragraph that "....the Brightsen Model views protons and neutrons as point particles, or at least ones that are indivisble..." This statement is factually incorrect, but in all fairness to Dr. Tannenbaum, he had no way to know this, since Mr. Brightsen never published on quark structure. However, in a December 31, 1988 memo from Mr. Brightsen titled "Introduction to the Nucleon Cluster Model" of the previous Nuclear Science Research Corporation (personal papers of Mr. Brightsen), Mr. Brightsen makes the following comments:
"Today the search for systematics by the nuclear physics community is concentrated almost totally on determining the sub-nuclear components (quarks, leptons, bosons) by means of powerful accelerators... In contrast to the efforts of the particle physicists, the ... Nucleon Cluster Model will focus on the possible explanations of the macroscopic properties that derive from the constitution of the nucleus, specifically their mass, charge, and spin. From a practical point of view, the future applications of these findings (...e.g., macroscopic nuclear properties such as beta-stability, nuclear cross sections, magnetic moments, etc.) is most important (... for national security and improvements of technology)". R. A. Brightsen, December, 1988.
Thus, it is clear that Mr. Brightsen held the view that protons and neutrons are in fact composed of sub-nuclear particles such as quarks, but he also felt that such "microscopic" knowledge was of little practical importance for the future of nuclear physics (at least in 1988). Mr. Brightsen's research was focused on the "macroscopic" properties that derive from the "microscopic" quark constitution of the atomic nucleus. The practical applications of this macroscopic view of the atomic nucleus are presented by Mr.Brightsen in his various publications (see Publications link). (Comments are welcome).
