I would like to post some Interesting information on Quarks. I think many people will be interested, and I expect some Contributions and a lot of Discussion.
What is your favourite Quark and why? I quite like the down quark because three of them make up my favourite Particle, the delta minus.
What do you think? Don't you enjoy the symmetry of the Quark structure?
You may think that this is not related to the learning of English, but I believe that it is.
I started this Topic on quarks initially because I was excited about it. Also I thought it was appropriate in an Internet based forum On the English language because people accessing the forum are made of Quarks. Furthermore there is a little bit of debate about the extent to which quarks are the underlying structure Of language, in the same way that words are the underlying structure of language.
Citation: S. Eidelman et al. (Particle Data Group), Phys. Lett. B 592, 1 (2004) (URL: http://pdg.lbl.gov)
QUARKS
The u-, d-, and s-quark masses are estimates of so-called \current-
quark masses," in a mass-independent subtraction scheme such as
MS at a scale 2 GeV. The c- and b-quark masses are the
\running" masses in the MS scheme. For the b-quark we also
quote the 1S mass. These can be di erent from the heavy quark
masses obtained in potential models.
u I (JP) = 1
2(1
2
+)
Mass m = 1:5 to 4 MeV [a] Charge = 2
3 e Iz = +1
2
mu/md = 0:3 to 0:7
d I(JP) = 1
2(1
2
+)
Mass m = 4 to 8 MeV [a] Charge = −1
3 e Iz=−1
2
ms/md = 17 to 22
m = (mu+md)/2 = 3:0 to 5:5 MeV
s I(JP) = 0(1
2
+)
Mass m = 80 to 130 MeV [a] Charge = −1
3 e Strangeness = −1
(ms { (mu + md)/2)(md − mu) = 30 to 50
c I (JP) = 0(1
2
+)
Mass m = 1:15 to 1:35 GeV Charge = 2
3 e Charm = +1
b I (JP) = 0(1
2
+)
Charge = −1
3 e Bottom = −1
Mass m = 4:1 to 4:4 GeV (MS mass)
Mass m = 4:6 to 4:9 GeV (1S mass)
HTTP://PDG.LBL.GOV Page 1 Created: 6/3/2004 12:15
Citation: S. Eidelman et al. (Particle Data Group), Phys. Lett. B 592, 1 (2004) (URL: http://pdg.lbl.gov)
t I (JP) = 0(1
2
+)
Charge = 2
3 e Top = +1
Mass m = 174:3 5:1 GeV (direct observation of top events)
Mass m = 178:1+10:4
− 8:3 GeV (Standard Model electroweak t)
p
t DECAY MODES Fraction (i /) Con dence level (MeV/c)
W q(q = b, s, d) {
W b {
`` anything [b,c] ( 9:42:4) % {
b {
q(q=u,c) [d] < 5:9 10−3 95% {
T = 1 weak neutral current (T1) modes
Z q(q=u,c) T1 [e] < 13:7 % 95% {
b0 (4th Generation) Quark, Searches for
Mass m > 190 GeV, CL = 95% (p p, quasi-stable b0)
Mass m > 199 GeV, CL = 95% (p p, neutral-current decays)
Mass m > 128 GeV, CL = 95% (p p, charged-current decays)
Mass m > 46:0 GeV, CL = 95% (e+e−, all decays)
Free Quark Searches
All searches since 1977 have had negative results.
NOTES
[a] The ratios mu/md and ms/md are extracted from pion and kaon masses
using chiral symmetry. The estimates of u and d masses are not without
controversy and remain under active investigation. Within the literature
there are even suggestions that the u quark could be essentially massless.
The s-quark mass is estimated from SU(3) splittings in hadron masses.
[b] ` means e or decay mode, not the sum over them.
[c] Assumes lepton universality and W-decay acceptance.
[d] This limit is for (t !
q)/(t ! W b).
[e] This limit is for (t ! Z q)/(t ! W b).
HTTP://PDG.LBL.GOV Page 2 Created: 6/3/2004 12:15
What is your favourite Quark and why? I quite like the down quark because three of them make up my favourite Particle, the delta minus.
What do you think? Don't you enjoy the symmetry of the Quark structure?
You may think that this is not related to the learning of English, but I believe that it is.
I started this Topic on quarks initially because I was excited about it. Also I thought it was appropriate in an Internet based forum On the English language because people accessing the forum are made of Quarks. Furthermore there is a little bit of debate about the extent to which quarks are the underlying structure Of language, in the same way that words are the underlying structure of language.
Citation: S. Eidelman et al. (Particle Data Group), Phys. Lett. B 592, 1 (2004) (URL: http://pdg.lbl.gov)
QUARKS
The u-, d-, and s-quark masses are estimates of so-called \current-
quark masses," in a mass-independent subtraction scheme such as
MS at a scale 2 GeV. The c- and b-quark masses are the
\running" masses in the MS scheme. For the b-quark we also
quote the 1S mass. These can be di erent from the heavy quark
masses obtained in potential models.
u I (JP) = 1
2(1
2
+)
Mass m = 1:5 to 4 MeV [a] Charge = 2
3 e Iz = +1
2
mu/md = 0:3 to 0:7
d I(JP) = 1
2(1
2
+)
Mass m = 4 to 8 MeV [a] Charge = −1
3 e Iz=−1
2
ms/md = 17 to 22
m = (mu+md)/2 = 3:0 to 5:5 MeV
s I(JP) = 0(1
2
+)
Mass m = 80 to 130 MeV [a] Charge = −1
3 e Strangeness = −1
(ms { (mu + md)/2)(md − mu) = 30 to 50
c I (JP) = 0(1
2
+)
Mass m = 1:15 to 1:35 GeV Charge = 2
3 e Charm = +1
b I (JP) = 0(1
2
+)
Charge = −1
3 e Bottom = −1
Mass m = 4:1 to 4:4 GeV (MS mass)
Mass m = 4:6 to 4:9 GeV (1S mass)
HTTP://PDG.LBL.GOV Page 1 Created: 6/3/2004 12:15
Citation: S. Eidelman et al. (Particle Data Group), Phys. Lett. B 592, 1 (2004) (URL: http://pdg.lbl.gov)
t I (JP) = 0(1
2
+)
Charge = 2
3 e Top = +1
Mass m = 174:3 5:1 GeV (direct observation of top events)
Mass m = 178:1+10:4
− 8:3 GeV (Standard Model electroweak t)
p
t DECAY MODES Fraction (i /) Con dence level (MeV/c)
W q(q = b, s, d) {
W b {
`` anything [b,c] ( 9:42:4) % {
b {
q(q=u,c) [d] < 5:9 10−3 95% {
T = 1 weak neutral current (T1) modes
Z q(q=u,c) T1 [e] < 13:7 % 95% {
b0 (4th Generation) Quark, Searches for
Mass m > 190 GeV, CL = 95% (p p, quasi-stable b0)
Mass m > 199 GeV, CL = 95% (p p, neutral-current decays)
Mass m > 128 GeV, CL = 95% (p p, charged-current decays)
Mass m > 46:0 GeV, CL = 95% (e+e−, all decays)
Free Quark Searches
All searches since 1977 have had negative results.
NOTES
[a] The ratios mu/md and ms/md are extracted from pion and kaon masses
using chiral symmetry. The estimates of u and d masses are not without
controversy and remain under active investigation. Within the literature
there are even suggestions that the u quark could be essentially massless.
The s-quark mass is estimated from SU(3) splittings in hadron masses.
[b] ` means e or decay mode, not the sum over them.
[c] Assumes lepton universality and W-decay acceptance.
[d] This limit is for (t !
q)/(t ! W b).
[e] This limit is for (t ! Z q)/(t ! W b).
HTTP://PDG.LBL.GOV Page 2 Created: 6/3/2004 12:15