Open Questions: The Strong Force and QCD

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Prerequisites: The standard model

See also: Quantum field theory


Quark confinement

Quark-gluon plasma


Nucleon spin


Lattice gauge theory

Relation to string theory (Maldacena)

Quark nuggets and strange matter

Recommended references: Web sites

Recommended references: Magazine/journal articles

Recommended references: Books


Recommended references: Web sites

Site indexes

Open Directory Project: Particle Physics: Chromodynamics
Categorized and annotated links. A version of this list is at Google, with entries sorted in "page rank" order.
Galaxy: Chromodynamics
Categorized site directory. Entries usually include descriptive annotations.

Sites with general resources

Relativistic Heavy Ion Collider
Web site of the research project which is investigating quark-gluon plasma.

Surveys, overviews, tutorials

Strong interaction
Article from Wikipedia. See also Quark, Gluon, Quantum chromodynamics.
Of gluons, atoms and strings
September 2009 article from Physics World. "An unusual alliance between physicists who study ultrahot plasmas and ultracold atoms is yielding intriguing results - and may even lead to an experimental test for string theory, as Barbara Jacak reveals."
Colourful calculations
Summary of December 2006 article from Physics World. "The formidable computational power of lattice QCD is finally allowing researchers to make solid predictions about the force that binds quarks inside protons and neutrons."
Liquid universe hints at strings
June 2005 article from Physics World. "Researchers at RHIC have seen convincing new evidence for a quark-gluon plasma. But it looks more like a perfect liquid than a gas, which could have implications for string theory."
Do pentaquarks really exist?
February 2005 article from Physics World, by Frank Close. "Results from a growing number of experiments at laboratories around the world are casting doubt on the recent discovery of particles containing five quarks."
Quarks, diquarks and pentaquarks
June 2004 article from Physics World, by Robert Jaffe and Frank Wilczek. "Pentaquarks do not fit into the traditional quark model of hadrons, but understanding these exotic new particles is offering fresh insights into the subtleties of the strong interaction."
Charmed particles at the double
October 2002 article from Physics World, by John Yelton. "The observation of baryons containing two charm quarks in a fixed-target experiment at Fermilab has surprised and puzzled the high-energy-physics community. Why do different doubly charmed baryons have such different masses?"
Physicists Find Evidence for an Exotic Baryon
Contains several explanatory articles on experiments which seem to have found evidence for the existence of pentaquarks. There are also a number of external links to further information.
Physicists report signs of new relatives of the proton
June 14, 2002 press release on the observation of a doubly-charmed baryon.
A strange quark plasma
October 2000 article from Physics World, by Emanuele Quercigh and Johann Rafelski. "Laboratory experiments have recreated the conditions that existed in the early universe before the quarks and gluons created in the big bang had formed the protons and neutrons that make up the world today."
The "Strangeness" of Protons
December 2000 Scientific American news article about experiments investigating the contribution of strange quarks to the proton's magnetic moment.
Fireballs of Free Quarks
Brief April 2000 article from Scientific American on the observation of quark-gluon plasma.
RHIC makes its debut
June 2000 news article from Physics World.
CERN claims quark-gluon first
February 2000 news article from Physics World.
Maybe this watched pot already boiled
May 2001 news article in Science News, about attempts to create a quark-gluon plama in the Relativistic Heavy Ion Collider.
Collider is cookin', but is it soup?
January 2001 news article in Science News, about attempts to create a quark-gluon plama in the Relativistic Heavy Ion Collider.
Melting nuclei re-create Big Bang broth
February 2000 news article in Science News, about attempts to create a quark-gluon plama in the CERN Super Proton Synchrotron.
Mashing atomic nuclei to create a quark soup
September 1996 news article in Science News, about discussions of quark-gluon plama at a conference on quark matter.

Recommended references: Magazine/journal articles

The First Few Microseconds
Michael Riordan; William A. Zajc
Scientific American, May 2006
Shattered Glass
David Appell
Scientific American, April 2004
The Search for QCD Exotics
Alex R. Dzierba; Curtis A. Meyer; Eric S. Swanson
American Scientist, September-October, 2000, pp 406-415
Quantum Chromodynamics provides the fundamental theoretical framework of the Standard Model. It predicts the existence of certain "exotic" particles such as "glueballs" consisting entirely of gluons. Currently ongoing experiments may detect such particles.
QCD Made Simple
Frank Wilczek
Physics Today, August 2000, pp. 22-28
Quantum chromodynamics (QCD) is the mathematical theory of the strong force. The theory resembles quantum electrodynamics (QED), the theory of the electromagnetic force, but with important differences.
Seeking the Mother of All Matter
Peter Weiss
Science News, August 26, 2000, pp. 136-138
The Relativistic Heavy Ion Collider (RHIC) has finally started to produce quark-gluon plasma from the collisions of very high energy gold ions.
The Glue that Holds the World Together
Robert Kunzig
Discover, July 2000, pp 64-69
Quantum Chromodynamics predicts a form of matter called quark-gluon plasma, which can exist only at extremely high energies. New accelerator experiments may be able to create it. The theory also suggests that common particles like protons are much more complex than normally envisioned.
The Mystery of Nucleon Spin
Klaus Rith; Andreas Schäfer
Scientific American, July 1999, pp. 58-63
Although the spin of the proton seems to be consistent with the spin of its constituent quarks, precise calculations to prove this are infeasible. Experiments indicate the situation is much more complex than had been supposed, leading to a "spin crisis", but theorists are gradually coming up with a plausible account of the situation.
Frank E. Close, Philip R. Page
Scientific American, November 1998, pp. 80-85
Gluons are particles that mediate the strong nuclear force. Clumps of gluons called glueballs that are predicted by the theory of the strong force may have been detected.
Quarks by Computer
Donald H. Weingarten
Scientific American, February 1996, pp. 116-120
Computations lasting a year on one of the largest supercomputers have helped confirm predictions of quantum chromodynamics. They have also accurately predicted the existence and properties of "glueballs".
Where Does the Proton Really Get Its Spin?
Robert L. Jaffe
Physics Today, September 1995, pp. 24-30
Polarized scattering experiments show that quarks actually contribute little to the proton's spin. This "spin crisis" is helping clarify QCD in contrast to a naive quark model.
The Search for Strange Matter
Henry J. Crawford; Carsten H. Greiner
Scientific American, January 1994, pp. 72-77
No theoretical principles seem to rule out assemblages of nuclear matter intermediate in size between atomic nuclei and neutron stars, yet nothing of the sort has ever been observed. If it exists, it may include "strange" quarks in addition to the usual "up" and "down" flavors.
Asymptotic Freedom
David J. Gross
Physics Today, January 1987, pp. 39-44
The strong force between quarks varies with the distance between them. But unlike electromagnetic force, for example, the force decreases with distance, due to dynamics of the vacuum. As the force becomes vanishingly small at very small distances, quarks in effect become "asymptoticall free".

Recommended references: Books


Copyright © 2002 by Charles Daney, All Rights Reserved