Standard
Model of Particle Physics| Standard
Model of Particle Physics |
In General > s.a. cosmological
standard model; particle
physics [context]; Weak Interactions.
* Particles: Classified
by representations of the symmetry group SU(3) × SU(2) × U(1);
Presently known particles can be divided into quarks (u, d; c, s; t, d)
(each in 3 colors), leptons (e, 
e;
,
mu; 
, tau),
and gauge bosons (graviton, 8 gluons, W +/–,
Z); Others are predicted by various extensions, like Higgs scalars
(from spontaneous gauge
symmetry breaking), gravitinos (> see supergravity),
etc; Cosmology puts an upper bound of 4 on the number of generations.
* Interactions: Four of them explain all presently known phenomena.
| Interaction | Strength | Range | Exchange particles | Theory | See also |
| gravitational | 10–40 |  |
graviton | > general relativity | > gravitation, quantum gravity |
| weak | 10–15 | cm | W +/–, Z | > electroweak | |
| electromagnetic | 10–2 | |
photon | > electroweak | > electromagnetism, QED |
| strong | 1 | 10–13 cm | gluons | > QCD |
The weak and electromagnetic interactions have in fact been unified by
the Weinberg-Salam electroweak theory, which has been experimentally tested;
aka hypercharge
force;
There could be additional forces (> see fifth
force).
* Theoretical problems:
Why do weak interactions couple differently to left-handed and right-handed
particles? The theoretical basis for the K-M matrix (too many parameters);
It is not enough to
account for
baryogenesis (GUTs or supersymmetry of some type needed); > s.a. Landau
Pole and Hierarchy Problem.
Relevant Concepts > s.a. Hypercharge;
renormalization.
* Isospin:
A quantum number associated with an SU(2) group, related to a transformation
between the u and d quarks; The isospin
SU(2) is a symmetry
group for strong interactions, but is broken when electromagnetic interactions
are turned
on, since Q = 
B + I3,
so [Q, I1,2] 
0;
Usually though Hem 
Hstrong,
and the breaking is small.
* Cabibbo angle: The parameter 
C that allows to obtain
the weakly interacting eigenstates as linear combinations of the quark mass
eigenstates,
like
d' = d cos C +
s sin C, s'
= –d sin C + s cos
C .
> Other topics: see Calabi-Yau Spaces; conformal symmetry; fine structure constant [variation]; unified theories.
Phenomenology and Experiment > s.a. early universe; QCD
phenomenology; [experimental physics and particle
physics].
* And experiment: 1989,
So far seems ok with experiment down to 10–16 cm;
some predictions confirmed to 10–12;
No problem including a fourth family, and can accommodate oscillations;
Possible problems include same sign dileptons; the decay Z0 → l+ l– 
,
and, Where
is the Higgs particle? 2002, experimental value of CP violation parameter
sin 2
approaches
prediction, but the g–2 problem remains.
* Sum rules: Relationships
between structure functions for different particles,
or expressions for them derived or guessed on the basis of their constitution
(hadrons in terms of quarks); Examples are the Bjorken sum rules
(no
evidence of any violation, but if found, could be serious) and Ellis-Jaffe
sum rules
(seem to be violated; no big deal); To verify them, use deep inelastic
scattering.
@ Cosmology: Kusenko & Langacker PLB(97)
[vacuum]; Bjorken PRD(01)
[and
], PRD(03)ht/02;
van der Bij PRD(07) [three generations and topology of the universe].
@ Particle physics: Froggatt et al NPB(94)
[fermion masses]; Dolgov
NPB(97)
[mass corrections in expanding universe]; Gynther & Vepsäläinen
JHEP(06)
[high-T, pressure]; Mangano a0802-in [LHC preview]; > s.a. astrophysics; atomic
physics; Regge Trajectory.
References > s.a. electroweak;
history of physics; lorentz
symmetry violations.
@ General: Donoghue et al 92; Leader & Predazzi 95; Cahn RMP(96)
[18 parameters]; Herrero hp/98-ln;
Riles CP(98)
[tests]; Bertin et al RNC(00)
[CKM matrix]; Quigg hp/00-in;
Rosner AJP(03)RL;
Particle Data Group PLB(04)
[reference]; Morri et al 04;
Oerter 05 [I];
Burgess & Moore 06; Cottinghman & Greenwood 07.
@ Strong interactions: Chew 62.
@ Hamiltonian/Dirac treatment: Lusanna NPPS(97)ht, ht/97-in;
Lusanna & Valtancoli IJMPA(98)ht/97.
@ Variations: Spaans gq/97 [topological];
Pomarol & Quirós PLB(98)
[extra dimensions]; Srivastava & Brodsky PRD(02)
[light front]; Blaha ht/02 [as
quantum computer]; Davoudiasl et al PLB(05)hp/04 [new
minimal model]; Ziino MPLA(07)
[with neutrino masses and
oscillations]; Zubkov PLB(07)
[extra discrete symmetry]; Grinstein et al a0704 [Lee-Wick,
with Higgs mass stabilization]; Alberghi et al a0804 [vacuum
energy and additional
particles]; > s.a. non-commutative
gauge theories, particle
physics [beyond
the standard model], time [2-time
physics].
Main page – Abbreviations – Journals – Comments – Other
sites – Acknowledgements
Send feedback and suggestions to bombelli at olemiss.edu – Modified
19 jun 2008