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# Physics Quarks Question in a past paper? Watch

1. EQ: K^– + p → K^+ + K^0 + X

My solution:

LHS strangeness = -1
RHS strangeness= +2
therefore, X must = -3 strangeness
therefore, the quark structure must be (sss).

Mark Scheme says:

1*** (strangeness on LHS is -1)strangeness on RHS without X is +2 /strangeness of X is -3 (one mark)
thus sss
OR
2*** strangeness on RHS without X is +2 / strangeness of X is -1(1 mark)
thus sdd (2 marks)

I don't understand the part labelled '2***' as strangeness would not be conserved! It can only be 1***, and why is solution 1*** only one mark?
2. I understand now, if you don't then lemme explain.

EDIT: The question => 'If strangeness is conserved in the equation, determine, with explanation, the quark structure of X'.

It's because K^0 has two potential quarks structures:
[1] (anti-strange, down) or...
[2] (anti-down, strange)

therefore we get two possible strangeness values, where
[1] = -1
[2] = +1.

Therefore, strangeness of X can be either -1 or -3, depending on which quark structure of K^0 you use. The question wants you to assume both structures are possible, which is not obvious if you haven't done anything like this before. Hope this makes sense and helps! =]

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Updated: May 18, 2016
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