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Template:More footnotes 51 years old Sportspersons Rusty from Wrigley, spends time with pastimes which includes beach, property agent in singapore developers in singapore and surf fishing. Continues to be inspired how enormous the earth is after making vacation to Saloum Delta.

The weak hypercharge in particle physics is a quantum number relating the electric charge and the third component of weak isospin. It is conserved(only terms that are overall weak-hypercharge neutral are allowed in the Lagrangian) and is similar to the Gell-Mann–Nishijima formula for the hypercharge of strong interactions (which is not conserved in weak interactions). It is frequently denoted Y_W and corresponds to the gauge symmetry U(1).

Definition

Weak hypercharge is the generator of the U(1) component of the electroweak gauge group, Template:Gaps and its associated quantum field B mixes with the W³ electroweak quantum field to produce the observed Template:Subatomic particle gauge boson and the photon of quantum electrodynamics.

Weak hypercharge, usually written as Y_W, satisfies the equality:

$Q=T_3+\frac{Y_{\mathrm{W}}}{2}$

where Q is the electrical charge (in elementary charge units) and T₃ is the third component of weak isospin. Rearranging, the weak hypercharge can be explicitly defined as:

$Y_{\mathrm{W}}=2(Q-T_3)$

	left-handed	el. charge Q	weak isospin T3	weak hyper- charge YW	right-handed	el. charge Q	weak isospin T3	weak hyper- charge YW
Leptons	Template:Subatomic particle, Template:Subatomic particle, Template:Subatomic particle	0	+1/2	−1	Do not interact (if exist at all)
	Template:Subatomic particle, Template:Subatomic particle, Template:Subatomic particle	−1	−1/2	−1	Template:Physics particle, Template:Physics particle, Template:Physics particle	−1	0	−2
Quarks	Template:Subatomic particle, Template:Subatomic particle, Template:Subatomic particle	+2/3	+1/2	+1/3	Template:Physics particle, Template:Physics particle, Template:Physics particle	+2/3	0	+4/3
	d, s, b	−1/3	−1/2	+1/3	Template:Physics particle, Template:Physics particle, Template:Physics particle	−1/3	0	−2/3

Note: sometimes weak hypercharge is scaled so that

$Y_{\mathrm{W}}=Q-T_3$

although this is a minority usage.

Hypercharge assignments in the Standard Model are determined up to a twofold ambiguity by demanding cancellation of all anomalies.

Baryon and lepton number

Weak hypercharge is related to baryon number minus lepton number via:

$X+2Y_{\mathrm{W}}=5(B-L)$

where X is a GUT-associated conserved quantum number. Since weak hypercharge is also conservedTemplate:Clarify this implies that baryon number minus lepton number is also conserved, within the Standard Model and most extensions.Template:Clarify

Neutron decay

Template:SubatomicParticle → Template:SubatomicParticle + Template:SubatomicParticle + Template:SubatomicParticle

Hence neutron decay conserves baryon number B and lepton number L separately, so also the difference B − L is conserved.

Proton decay

Proton decay is a prediction of many grand unification theories.

Template:SubatomicParticle → Template:SubatomicParticle + Template:SubatomicParticle → Template:SubatomicParticle + 2Template:SubatomicParticle

Hence proton decay conserves B − L, even though it violates both lepton number and baryon number conservation.

See also

• Standard Model (mathematical formulation)