Weinberg-Salam Electroweak Theory

In General > s.a. particle physics; symmetry breaking.
* Idea: A unified theory of electroweak interactions, a gauge theory with gauge group G = SU(2) × U(1) (the left-handed and the hypercharge groups).
* History: Proposed in the 1960s by Weinberg, Salam, and Glashow, but did not attract much attention until 't Hooft showed that it was renormalizable.
* Motivation: It explains the masslessness of the neutrino and the structure of the weak interactions by the presence of the gauged chiral symm, and incorporates electrodynamics by using the concept of spontaneously broken symmetry.
* Symmetry breaking: The symmetry group G is broken to the electromagnetic U(1) by the Higgs.

Particle Content > s.a. particle types [leptons]; solutions of gauge theories [sphalerons].
* Idea: The fundamental particles are quarks, leptons and Higgs particles, with forces mediated by W ^+/–, Z⁰ and (the W's and Z get their masses from the Higgs particles); With a Cartan basis for the Lie algebra of the gauge group G, the gauge connection can be written

A_G = A_em + A_Z + A_W+ + A_W– ,

where the first two generate the Cartan subalgebra.

Intermediate Vector Bosons
* Idea: The particles W ⁺, W ^– and Z⁰, mediators for the weak interaction.
* Z⁰: Mass m_Z 90 GeV.
@ General references: Hung & Quigg Sci(80); Rubbia RMP(85); Taubes 86, Denegri PRP(04) [discovery]; Tenchini & Verzegnassi 07.
@ Related topics: Nikishov JETP(01)ht [W boson in constant electromagnetic field].

Higgs Bosons > s.a. branes; Higgs Mechanism.
* Idea: The particles responsible, through the Higgs mechanism, for giving mass to quarks and intermediate bosons in the Weinberg-Salam electroweak theory, breaking the symmetry with a non-zero vev.
* Remark: There should be at least 4 Higgs bosons (a complex doublet), but 3 show up only as the longitudinal modes of the Ws and Z⁰; In the MSSM, one needs two complex doublets, and there may be extra fields, such as a Higgs singlet.
* 1997: According to Gordon Kane (U of Michigan), high-precision experiments at LEP, Fermilab, and SLAC now support the claim, for the first time with any statistical weight, that the Higgs does exist; The supersymmetry model [@ news pn(96)apr] of particle interactions predicts that the Higgs mass should be less than about 150 GeV; LEP could by 1999 have spotted the Higgs if its mass were no more than 95 GeV; Fermilab (with its new much more intense beams) could probe for a Higgs mass up to 130 GeV by 2002; The LHC at CERN could extend the range up to 150 GeV by 2010.
* 1999: Rumors of detection by OPAL at LEP, with m_H 91 GeV.
* 2000: More rumors of detection at LEP, with m_H 115 GeV; CERN delays LEP shutdown by a month.
* 2001: Fermilab's Tevatron resumes operations in March for five years, and can search up to 180 GeV.
* 2004: Estimated 115 GeV < m_H < 251 GeV, with best fit to top data from D0 at tevatron at 117 GeV; Tevatron Run II has a chance of finding it, otherwise LHC in 2007.
* 2009: Estimated 114 GeV < m_H < 185 GeV, from LEP data and theoretical analysis, respectively, and Fermilab's CDF and D0 experiments now exclude the region 160–170 GeV
@ General references: Veltman SA(86)#5; Aitchison PW(89)jul; L3 collaboration, ALEPH collab PLB(00) [discovery?]; Collins SA(01)feb [CERN shutdown]; Kane SA(05)jul [search]; Parker pw(06)oct, news pn(08)apr, news indep(08)apr [search with LHC]; CDF & D0 a0903-in and PT(09)apr.
@ Related topics: Kujat & Scherrer PRD(00)ap/99 [and cmb]; Miller et al PLB(01) [measuring the spin]; Nayak & Smith PRD(06)hp [from black holes at LHC]; Faddev a0811-in [alternative interpretation]; Popa a0910 [bounds on mass from astrophysics and cosmology].

References > s.a. atomic physics; relativistic cosmological models [coupled to gravity]; unified theories [with gravity].
@ I, II: Weinberg SA(74)jul; Langacker & Mann PT(89)dec; Aitchison & Hey 04.
@ General: Salam & Ward NC(59), NC(61); Glashow NP(61); Salam & Ward PL(64); Weinberg PRL(67); Salam in(68); Paschos 07; Porsev et al PRL(09) [precision determination of coupling from parity violation in a cesium atom].
@ Overviews: Taylor 76; Weinberg RMP(80); Salam RMP(80), Sci(80)nov; Glashow RMP(80); Altarelli et al IJMPA(98) [status]; Gurtu IJMPA(03) [tests]; Wood IJMPA(07).
@ Quantum theory: Kraus AP(98)ht/97 [renormalization]; Su ht/00 [Hamiltonian path integral].
@ Symmetry breaking: Dobrescu PLB(99) [from extra dimensions]; Lepora & Kibble JHEP(99) [vacuum geometry]; Arkani-Hamed et al JHEP(02); Hill & Simmons PRP(03) [strong dynamics]; Quigg CP(07) [and LHC]; Djouadi PRP(08) [Higgs boson].
@ Modified versions: McCorkle ht/96 [from spacetime theory of matter]; Pervushin & Smirichinski gq/97 [conformally invariant, and general relativity]; Finkelstein IJMPA(05)ht/04 [q-deformed]; Loewe et al PLB(05)hp/04 [finite T and density]; Lecian & Montani IJMPD(06)gq [geometrization, Riemann-Cartan]; Moffat & Toth a0906-in [without a Higgs particle]; > s.a. supersymmetry phenomenology; variation of constants.
@ Related topics: news pw(05)jul [decrease with distance]; > s.a. brans-dicke theory; Quantions.

main page – abbreviations – journals – comments – other sites – acknowledgements
send feedback and suggestions to bombelli at olemiss.edu – modified 28 oct 2009