The intrinsic parity of a quark is and of an antiquark

PHYSICS · Multi-part · Fermi University Physics · Particle Physics & Quantum Fields · Symmetry, groups and the quark model · Symmetry, groups and the quark model

Symmetry and Flavour, Ch The constituent quark model: wave functions, magnetic moments and hyperfine masses

Problem

The intrinsic parity of a quark is

+1

and of an antiquark

-1

. Consider the ground-state (

L=0

) mesons built from an up quark

u

and a strange antiquark

\bar s

: the pseudoscalar

K^+

(

S=0

) and the vector

K^{*+}

(

S=1

). ((a)) Write the total parity of a quark-antiquark pair with orbital angular momentum

L

as a product of the intrinsic parities and the orbital parity

(-1)^L

, and evaluate it for

L=0

. ((b)) Using

J=L+S

for

L=0

, give

J

for the

S=0

and

S=1

spin couplings, and hence state

J^P

for the

K^+

and

K^{*+}

. ((c)) Check the results against the measured values

J^P(K^+)=0^-

and

J^P(K^{*+})=1^-

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