What we know and what we don’t know about the proton spin after 30 years

Ji, Xiangdong; Yuan, Feng; Zhao, Yong

doi:10.1038/s42254-020-00248-4

Cited by 87 publications

(52 citation statements)

References 138 publications

(185 reference statements)

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“…The observe spin from the quarks was nearly zero. And then the following experiments like HERMES and COMPASS [52] reports the quark effect of only 33(6) % and 26 -36 % to the spin (1/2)of the proton. The missing spin of the proton is about 67 % which requires other explanations like the gluon effect or quark orbital angular momentum effect in terms of the quantum chromodynamics (QCD).…”

Section: Partial Mass Calculations Of Elementary Fermions and Proton Spin Crisismentioning

confidence: 99%

Unified Explanation of Big Bang, Inflation, Charged Black Hole Decay, Galaxy Formation, Proton Spin Crisis and Elementary Particle Masses

Hwang¹

2021

Preprint

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Space-time evolution is briefly explained by using the 3-dimensional quantized space model (TQSM) based on the 4-dimensional (4-D) Euclidean space. The energy (E=cDtDV), charges (|q|= cDt) and absolute time (ct) are newly defined based on the 4-D Euclidean space. The big bang is understood by the space-time evolution of the 4-D Euclidean space but not by the sudden 4-D Minkowski space-time creation. The big bang process created the matter universe with the positive energy and the partner anti-matter universe with the negative energy from the CPT symmetry. Our universe is the matter universe with the negative charges of electric charge (EC), lepton charge (LC) and color charge (CC). This first universe is made of three dark matter -, lepton -, and quark - primary black holes with the huge negative charges which cause the Coulomb repulsive forces much bigger than the gravitational forces. The huge Coulomb forces induce the inflation of the primary black holes, that decay to the super-massive black holes. The dark matter super-massive black holes surrounded by the normal matters and dark matters make the galaxies and galaxy clusters. The spiral arms of galaxies are closely related to the decay of the 3-D charged normal matter black holes to the 1-D charged normal matter black holes. The elementary leptons and quarks are created by the decay of the normal matter charged black holes, that is caused by the Coulomb forces much stronger than the gravitational forces. The Coulomb forces are very weak with the very small Coulomb constants (k1(EC) = kdd(EC) ) for the dark matters and very strong with the very big Coulomb constants (k2(EC) = knn(EC)) for the normal matters because of the non-communication of the photons between the dark matters and normal matters. The photons are charge dependent and mass independent. But the dark matters and normal matters have the similar and very weak gravitational forces because of the communication of the gravitons between the dark matters and normal matters. The gravitons are charge independent and mass dependent. Note that the three kinds of charges (EC, LC and CC) and one kind of mass (m) exist in our matter universe. The dark matters, leptons and quarks have the charge configurations of (EC), (EC,LC) and (EC,LC,CC), respectively. Partial masses of elementary fermions are calculated, and the proton spin crisis is explained. The charged black holes are not the singularities.

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Section: Partial Mass Calculations Of Elementary Fermions and Proton Spin Crisismentioning

confidence: 99%

Unified Explanation of Big Bang, Inflation, Charged Black Hole Decay, Galaxy Formation, Proton Spin Crisis and Elementary Particle Masses

Hwang¹

2021

Preprint

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“…Note that the constraint forC holds also when 2 = 0 as a consequence of the conservation of T μν . Even though | p, s is in general not an eigenstate of the AM operator, 8 the expectation value understood in the sense of Eq. ( 48) is well-defined.…”

Section: Am Sum Rulesmentioning

confidence: 99%

“…Reviews about key developments and achievements in this field can be found in Refs. [1][2][3][4][5][6][7][8]. A fundamental question is the decomposition of the nucleon spin into its constituents' intrinsic and orbital angular momentum contributions.…”

Section: Introductionmentioning

confidence: 99%

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Relativistic spin sum rules and the role of the pivot

Lorcé

2021

Eur. Phys. J. C

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Spin sum rules depend on the choice of a pivot, i.e. the point about which the angular momentum is defined, usually identified with the center of the nucleon. The latter is however not unique in a relativistic theory and has led to apparently contradictory results in the literature. Using the recently developed phase-space approach, we compute for the first time the contribution associated with the motion of the center of the nucleon, and we derive a general spin sum rule which reduces to established results after appropriate choices for the pivot and the spin component.

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“…These methods, dis cussed in a Review 2 by Xiangdong Ji, Feng Yuan and Yong Zhao in this issue, together with advances in spin ab initio calculations in lattice quantum chromo dynamics, have revealed much about the proton spin structure. The final pieces of the puzzle are expected to come from experiments at the Electron-Ion Collider (EIC) 2 . The construction of the EIC has just started and in a Comment in this issue, James Yeck explains the challenges in delivering big science projects and EIC in particular.…”

mentioning

confidence: 99%

Proton puzzles

2021

Nat Rev Phys

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What we know and what we don’t know about the proton spin after 30 years

Cited by 87 publications

References 138 publications

Unified Explanation of Big Bang, Inflation, Charged Black Hole Decay, Galaxy Formation, Proton Spin Crisis and Elementary Particle Masses

Unified Explanation of Big Bang, Inflation, Charged Black Hole Decay, Galaxy Formation, Proton Spin Crisis and Elementary Particle Masses

Relativistic spin sum rules and the role of the pivot

Proton puzzles

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