What is the Quark Composition of Specific Mesons and Antibaryons?

[BOYLANATOR]

Homework Statement

Write down the quark content of the following particles, made of (u; d; s) and their antiquarks:

(a) A meson with strangeness S = 1, and isospin component I3 = 1/2

(b) An antibaryon with strangeness S = 0, and isospin I3 = -3/2

The Attempt at a Solution

a) A meson consists of one quark and one antiquark. The strangeness comes from an anti-strange quark and an up quark satisfies the isospin So we have u\bar{s}

b) The antibaryon must have three antiquarks and in this case none can be strange. In order to have isospin of -3/2 we must have three antiup quarks, ie \bar{u}\bar{u}\bar{u}

My answer for a) is correct and b) seems ok.

Here is the given solution to b).

"An antibaryon contains three antiquarks. There can be no strange antiquarks if S=0 Also,
isospin component I3 = -3/2 tell us there must be three antiup quarks. So the answer is \bar{d}\bar{d}\bar{d}."

This is just a typo at the end, right?

 

[lightgrav]

If they had wanted a (regular) baryon, it would have been ddd , right?
I'll bet the question WAS originally (previous edition) for a baryon with I3 = - 3/2
When they changed the problem (for the new edition), the editor changed the (regular) to anti-,
but didn't notice that he also needed to negate the isospin projection (or change d to u in the solution).

 

[BOYLANATOR]

Thanks. I just wanted to make sure as this stuff is new to me.