A collaboration reports a new light meson resonance with measured quantum numbers…

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 Parity, charge conjugation and time reversal as operators, and the CPT theorem

Problem

A collaboration reports a new light meson resonance with measured quantum numbers

J^{PC} = 1^{-+}

decaying strongly to

\pi^-\pi^+\pi^0

, and calls it a

\pi_1

candidate. ((a)) Using

P = (-1)^{L+1}

and

C = (-1)^{L+S}

for a quark-antiquark pair (with

S = 0

S=1

from two spin-half quarks, and

J

built from

\mathbf L

and

\mathbf S

), predict whether any combination of orbital angular momentum

L

and spin

S

can give

J^{PC} = 1^{-+}

for an ordinary

q\bar q

meson. ((b)) State what a confirmed observation of a

1^{-+}

resonance would imply about its internal structure. ((c)) Name an established resonance with this quantum-number combination.

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