Gravity-like theories give insight into the strong force

Jun 07, 2010 by Kandice Carter

A new computation of the constant that describes the strength of the force between the quarks in a proton may help theorists tackle one of the most challenging problems of physics: analytically solving the theory of QCD and determining its coupling strength at large distances.

Quantum Chromodynamics is the theory of the strong force, describing how combine to make the protons and neutrons in the of the atom. While the strong force strength is known to be weak at small separation between quarks, its value and behavior at large distances is uncertain and hotly debated.

To tackle that problem, three scientists, including one based at DOE's Jefferson Lab, computed the constant that describes the strength of the force between the quarks in a proton. They computed the constant using a novel approach: the Maldacena conjecture, a method that connects QCD-like theories in physical space to gravity-like theories in a mathematical five-dimensional space.

The calculation showed that the Maldacena conjecture provides an analytical way to solve QCD. Their analysis also clarifies why different earlier calculations have yielded different values for the constant, thus giving new insights into how to consistently define coupling, as well as providing new non-trivial tests of QCD.

A paper describing the result was published on May 28 in the journal Physical Review D.

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User comments : 9

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MorituriMax
2.3 / 5 (3) Jun 07, 2010
Oh! The Maldacena conjecture! (slaps forehead) Was THAT all it was?!

Heh..
nuge
1 / 5 (1) Jun 07, 2010
Isn't Maldacena that String Theory bloke?
Sonhouse
Jun 07, 2010
This comment has been removed by a moderator.
solidspin
not rated yet Jun 08, 2010
yes, as a matter of fact -

it WAS a lot of very useful information...
jsa09
5 / 5 (2) Jun 08, 2010
I just feel the this article could be twice or three times as long and go into a little more depth. Not that I want to be drowned in Math; but a little mix of theory and history to put everything into context would be marvelous.
daywalk3r
3.1 / 5 (15) Jun 08, 2010
A new computation of the CONSTANT that describes the strength of the force between the quarks in a proton
Fail. The only true/real constants are all geometry/symetry based. So unless such relation is found and at least attempted to be understood (expressed mathematically), any other attempt to define/pinpoint it is, at least in my book, just an indication that a wrong approach was chosen..

Cosmological "constant" anyone? That was an analytical/statistical approach too :-|
PinkElephant
5 / 5 (2) Jun 08, 2010
@daywalk3r,

There are lots of non-geometrical constants in physics. For instance, the gravitational constant, vacuum permittivity constant, speed of light, and mass of an electron come to mind.

Perhaps at some deeper (heretofore unknown) level all these "constants" indeed derive from structural/geometric relationships. However, lacking access to such fundamental insight we can only treat them as empirical constants, and move along.
daywalk3r
2.7 / 5 (17) Jun 09, 2010
Perhaps at some deeper (heretofore unknown) level all these "constants" indeed derive from structural/geometric relationships. However, lacking access to such fundamental insight we can only treat them as empirical constants, and move along.
Exactly. That was my point.

Also that many of the currently known "constants", which are based on empirical measurements and we have yet to discover the background of, might not even be real constants at all.

Everything in the Universe is relative, there are no absolutes, so every real constant is, in fact, just a representation of a relation (or multiples of them) at some point.

Of course we don't know most of these relations yet - physics would be no fun anymore if we did, after all :) As the route to infinity is infinitively long, it is an eternal task for physics research to discover them all.
Gene_H
not rated yet Jun 09, 2010
For interested readers this older article may be interesting as an introduction into subject from mainstream physics perspective.

http://www.hep.ph...vans.pdf

If doesn't deal with QCD calculations of force constant, but mass of proton - but the usage of Maldacena's conjecture is analogous here.

For nonformal intro into Maldacena duality this article may be interesting, too:

http://www.tinyurl.cz/rgb
daywalk3r
3.1 / 5 (15) Jun 09, 2010
There are lots of non-geometrical constants in physics. For instance, the gravitational constant, vacuum permittivity constant, speed of light, and mass of an electron come to mind.
And a major step forward, on the route to knowledge, would be to "get rid" of them :) - eg. find the fundamental relations, that define them, rather than "derivation" from empirical measurements.