Not to be confused with Hypercharge or Weak charge.
Flavour in particle physics
Flavour quantum numbers
Isospin: I or I3
Charm: C
Strangeness: S
Topness: T
Bottomness: B′
Related quantum numbers
Baryon number: B
Lepton number: L
Weak isospin: T or T3
Electric charge: Q
X-charge: X
Combinations
Hypercharge: Y
Y = (B + S + C + B′ + T)
Y = 2 (Q − I3)
Weak hypercharge: YW
YW = 2 (Q − T3)
X + 2YW = 5 (B − L)
Flavour mixing
CKM matrix
PMNS matrix
Flavour complementarity
v
t
e
In the Standard Model of electroweak interactions of particle physics, the weak hypercharge is a quantum number relating the electric charge and the third component of weak isospin. It is frequently denoted and corresponds to the gauge symmetry U(1).[1][2]
It is conserved (only terms that are overall weak-hypercharge neutral are allowed in the Lagrangian). However, one of the interactions is with the Higgs field. Since the Higgs field vacuum expectation value is nonzero, particles interact with this field all the time even in vacuum. This changes their weak hypercharge (and weak isospin T3). Only a specific combination of them, (electric charge), is conserved.
Mathematically, weak hypercharge appears similar to the Gell-Mann–Nishijima formula for the hypercharge of strong interactions (which is not conserved in weak interactions and is zero for leptons).
In the electroweak theory SU(2) transformations commute with U(1) transformations by definition and therefore U(1) charges for the elements of the SU(2) doublet (for example lefthanded up and down quarks) have to be equal. This is why U(1) cannot be identified with U(1)em and weak hypercharge has to be introduced.[3][4]
Weak hypercharge was first introduced by Sheldon Glashow in 1961.[4][5][6]
^Cite error: The named reference Donoghue-Golowich-Holstein-1994-DynSM was invoked but never defined (see the help page).
^Cite error: The named reference Cheng-Li-2006-GaThElPP was invoked but never defined (see the help page).
^Cite error: The named reference Tully-2012-Nutsh was invoked but never defined (see the help page).
^ abCite error: The named reference Glashow-1961-02-NucPh was invoked but never defined (see the help page).
^Cite error: The named reference Hoddeson-Brown-Riordan-etal-1997 was invoked but never defined (see the help page).
^Cite error: The named reference Quigg-2015-10-19-ARevNuPaSc was invoked but never defined (see the help page).
property, weakhypercharge, was invented, defined as Y W = 2 ( Q − T 3 ) , {\displaystyle Y_{\text{W}}=2\,(Q-T_{3}),} where YW is the weakhypercharge of a...
electrodynamics; the resulting Z0 and γ0 likewise have zero weak isospin. WeakhyperchargeWeak charge Mathematical formulation of the Standard Model Glashow...
{\displaystyle \psi _{\mathrm {e} }^{\rm {R}}} (because they have different weakhypercharges). A distinction can thus be made between, for example, the mass and...
dynamics of the system. These fields are the weak isospin fields W1, W2, and W3, and the weakhypercharge field B. This invariance is known as electroweak...
quantities, such as weak isospin, weakhypercharge, or the vector coupling of a fermion to the Z boson (i.e. the coupling strength of weak neutral currents)...
to the projection of weak isospin T 3 {\displaystyle T_{3}} and the weakhypercharge Y w {\displaystyle Y_{w}} . Isospin and weak isospin are related to...
fields of the weak isospin SU(2) and the weakhypercharge U(1) symmetries to three massive vector bosons ( W+ , W− , Z0 ) mediating the weak interaction...
together known as the weak bosons or more generally as the intermediate vector bosons. These elementary particles mediate the weak interaction; the respective...
the American Philosophical Society (2002) Neutral current Tadpole Weakhypercharge List of Jewish Nobel laureates "Glashow". The American Heritage Dictionary...
where g3 is the color gauge coupling, g2 is the weak isospin gauge coupling, and g1 is the weakhypercharge gauge coupling. This equation describes how the...
the weakhypercharge U(1) symmetry. Note: This article uses the scaling convention where the electric charge, Q, the weak isospin, T3, and the weak hypercharge...
to the strong interaction and the weak interaction, having zero electric charge, zero weakhypercharge, zero weak isospin, and, as with the other leptons...
SU(2) which allow only discrete charges, the remaining component, the weakhypercharge interaction is described by an abelian symmetry U(1) which in principle...
physical properties. Lepton number Flavour (particle physics) Isospin Hypercharge Proton decay B − L Nave, R. "The Color Force". Archived from the original...
couplings are very small. Age of the universe B − L Virtual black hole Weakhypercharge X and Y bosons Iron star Ishfaq Ahmad (1969), "Radioactive decays by...
the bottom quark can decay into either an up quark or charm quark via the weak interaction. CKM matrix elements Vub and Vcb specify the rates, where both...
experiences all four fundamental interactions: gravitation, electromagnetism, weak interactions, and strong interactions. The antiparticle of the strange quark...
(an elementary particle with spin of 1 /2) that interacts only via the weak interaction and gravity. The neutrino is so named because it is electrically...
in second-order weak reactions, where there are mixes of K0 and K0 mesons. All in all, the amount of strangeness can change in a weak interaction reaction...
a transfer of electric charge (as well as a transfer of weak isospin, while weakhypercharge is not transferred), it is known as “charged current”. By...
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