What is the status at the moment about "proton and neutron spincrisis" ?

What is the status at the moment about "proton and neutron spin
crisis" ?

Experiments (EMC and SMC ? gave result 1988 and 1993 ? that

"sum of spins of quarks inside the proton is = 0"

and also

"sum of spins of quarks inside the neutron is = 0".


Hannu

Dear mathematician:

On Mar 23, 7:55*am, mathematician wrote:
What is the status at the moment about "proton
and neutron spin crisis" ?

Experiments (EMC and SMC ? gave result 1988
and 1993 ? that

"sum of spins of quarks inside the proton is = 0"

*and also

"sum of spins of quarks inside the neutron is = 0".

A work in progress.
http://arxiv.org/abs/0911.1974

David A. Smith

On 23 maalis, 18:24, dlzc wrote:
Dear mathematician:

On Mar 23, 7:55*am, mathematician wrote:

What is the status at the moment about "proton
and neutron spin crisis" ?

Experiments (EMC and SMC ? gave result 1988
and 1993 ? that

"sum of spins of quarks inside the proton is = 0"

*and also

"sum of spins of quarks inside the neutron is = 0".

A work in progress.http://arxiv.org/abs/0911.1974

David A. Smith

If I understood their paper right:

pion cloud and three core quarks inside the proton
means actually five quarks inside the proton?

What experiments says about the number of
quarks inside the proton?

Hannu Poropudas

On 24 maalis, 10:34, Hannu Poropudas wrote:
On 23 maalis, 18:24, dlzc wrote:



Dear mathematician:

On Mar 23, 7:55*am, mathematician wrote:

What is the status at the moment about "proton
and neutron spin crisis" ?

Experiments (EMC and SMC ? gave result 1988
and 1993 ? that

"sum of spins of quarks inside the proton is = 0"

*and also

"sum of spins of quarks inside the neutron is = 0".

A work in progress.http://arxiv.org/abs/0911.1974

David A. Smith

If I understood their paper right:

pion cloud and three core quarks *inside the proton
means actually five quarks inside the proton?

What experiments says about the number of
quarks inside the proton?

Hannu Poropudas

References:

EMC, Ashman,J. et al. 1988.
Phys. Lett. B206 (1988) 364.

SMC Collaboration, Adera,B. et al. 1993.
Phys. Lett. B302, 553 (1993).

EMC Collaboration, 1989.
Nucl. Phys. B328, 1 (1989).

References about number of quarks inside proton:

Gross,D.J. and Llewellyn-Smith,C.H. 1969.
Nucl. Phys. B14 (1969) 337.

Adler,S.L. 1966.
Phys. Rev. 143 (1966) 1144.

Niinikoski,T. 1990.
Protonin spinkriisi.
Arkhimedes, Vuosikerta 42, 3/1990,
516 pages, pages 411-430.

Should these old references from 1966 and 1969
be reinvestigated carefully and correctly updated,
if quark content of the proton would really be five ?

Hannu

mathematician wrote:
Should these old references from 1966 and 1969
be reinvestigated carefully and correctly updated,
if quark content of the proton would really be five ?

In QCD, I'm pretty sure that the number of quarks in a nucleon is not a good
quantum number. That is, the number of quarks has no definite value. The number
of valence quarks is 3, but that is a different statement.

For the solar system, it is an excellent approximation to count the planets,
asteroids, comets, and sun, add up their masses and kinetic energies, subtract
the gravitational binding energy, and obtain the total energy of the entire system.

For an atom, it is an excellent approximation to count the electrons and the
nucleus, add up their masses and kinetic energies, subtract the electromagnetic
binding energy, and obtain the total energy of the atom.

That procedure breaks down for a nucleus, and gives wildly incorrect answers.
There are several reasons for this, among which a the impossibility of
counting, the much stronger binding force, the structure of that force, and the
fact that the sum of the valence quark masses is only ~10% of the total (for the
other examples, the constituent masses are typically 99% of the total).


Tom Roberts