lpetrich
Contributor
In another forum, I did some rather naive quark-model calculations, but rather successful ones: mathematical and geometric model for mass of proton.
Much of the thread was taken up with numerological crackpottery, and I noted that there is a well-established mainstream theory of the proton's mass: A rather technical presentation on finding the proton's mass, [hep-ex/0002035] Measurement of the Running of the Fine-Structure Constant, Current advances: The fine-structure constant, Backreaction: Asymptotic Freedom and the Coupling Constant of QCD, Theoretical Elementary Particle Physics Group @ KTH - Research Topics: Grand Unified Theories (GUTs), http://2.bp.blogspot.com/_ws8XY4ubvXg/R1qrf-HmpFI/AAAAAAAAAaY/YR29Ynif3-0/s1600-h/smmssm.jpg, [hep-ph/0012288] Beyond the Standard Model (In Search of Supersymmetry), [1006.1311] Electromagnetic mass splittings of the low lying hadrons and quark masses from 2+1 flavor lattice QCD+QED, http://www.riken.go.jp/lab-www/theory/colloquium/kinoshita.pdf
The source of my numbers: Particle Data Group. Here, m is mass in MeV and mu is magnetic moment in a unit called the nuclear magneton. In ()'s, the quark content and spin.
Proton (uud,1/2): m = 938.272081, mu = 2.792847351
Neutron (udd,1/2): m = 939.565413, mu = - 1.9130427
Collectively: nucleons
Delta (uuu,uud,udd,ddd,3/2): m = 1210
Lambda (uds,1/2): m = 1115.683, mu = -0.613
Sigma+ (uus,1/2): m = 1189.37, mu = 2.458
Sigma0 (uds,1/2): m = 1192.642, (from transitions, |mu| = 1.61)
Sigma- (dds,1/2): m = 1197.449, mu = -1.160
Sigma-x+ (uus,3/2): m = 1382.80
Sigma-x0 (uds,3/2): m = 1383.7
Sigma-x- (dds,3/2): m = 1387.2
Xi0 (uss,1/2): m = 1314.86, mu = -1.250
Xi- (dss,1/2): m = 1321.71, mu = -0.6507
Xi-x0 (uss,3/2) m = 1531.80
Xi-x- (dss,3/2) m = 1535.0
Omega- (sss,3/2): m = 1672.45, mu = -2.02
Averaging over the up and down quarks, the masses are:
Nucleon: 938.918747
Delta: 1210
Lambda: 1115.683
Sigma: 1193.16
Sigma-x: 1384.6
Xi: 1318.28
Xi-x: 1533.4
Omega: 1672.45
So there is a big splitting due to the QCD spin-spin interaction.
Much of the thread was taken up with numerological crackpottery, and I noted that there is a well-established mainstream theory of the proton's mass: A rather technical presentation on finding the proton's mass, [hep-ex/0002035] Measurement of the Running of the Fine-Structure Constant, Current advances: The fine-structure constant, Backreaction: Asymptotic Freedom and the Coupling Constant of QCD, Theoretical Elementary Particle Physics Group @ KTH - Research Topics: Grand Unified Theories (GUTs), http://2.bp.blogspot.com/_ws8XY4ubvXg/R1qrf-HmpFI/AAAAAAAAAaY/YR29Ynif3-0/s1600-h/smmssm.jpg, [hep-ph/0012288] Beyond the Standard Model (In Search of Supersymmetry), [1006.1311] Electromagnetic mass splittings of the low lying hadrons and quark masses from 2+1 flavor lattice QCD+QED, http://www.riken.go.jp/lab-www/theory/colloquium/kinoshita.pdf
The source of my numbers: Particle Data Group. Here, m is mass in MeV and mu is magnetic moment in a unit called the nuclear magneton. In ()'s, the quark content and spin.
Proton (uud,1/2): m = 938.272081, mu = 2.792847351
Neutron (udd,1/2): m = 939.565413, mu = - 1.9130427
Collectively: nucleons
Delta (uuu,uud,udd,ddd,3/2): m = 1210
Lambda (uds,1/2): m = 1115.683, mu = -0.613
Sigma+ (uus,1/2): m = 1189.37, mu = 2.458
Sigma0 (uds,1/2): m = 1192.642, (from transitions, |mu| = 1.61)
Sigma- (dds,1/2): m = 1197.449, mu = -1.160
Sigma-x+ (uus,3/2): m = 1382.80
Sigma-x0 (uds,3/2): m = 1383.7
Sigma-x- (dds,3/2): m = 1387.2
Xi0 (uss,1/2): m = 1314.86, mu = -1.250
Xi- (dss,1/2): m = 1321.71, mu = -0.6507
Xi-x0 (uss,3/2) m = 1531.80
Xi-x- (dss,3/2) m = 1535.0
Omega- (sss,3/2): m = 1672.45, mu = -2.02
Averaging over the up and down quarks, the masses are:
Nucleon: 938.918747
Delta: 1210
Lambda: 1115.683
Sigma: 1193.16
Sigma-x: 1384.6
Xi: 1318.28
Xi-x: 1533.4
Omega: 1672.45
So there is a big splitting due to the QCD spin-spin interaction.
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