Which of the following processes is allowed and which...

Which of the following processes is allowed and which forbidden by strangeness conservation? (a) $\pi^{-}+p \rightarrow K^{-}+p$; (b) $\pi^{-}+p \rightarrow K^{+}+\Sigma^{-}$; (c) $K^{-}+p \rightarrow K^{+}+\Xi^0+\pi^{-}$; (d) $K^{+}+p \rightarrow K^{-}+\Xi^0+\pi^{-}$.

Key Concepts

Interaction Types and Quantum Number Conservation

Different fundamental interactions have different conservation rules. For example, while the strong and electromagnetic interactions strictly conserve strangeness, the weak interaction does not necessarily conserve it. This distinction is key when analyzing particle reactions to determine whether they are allowed or forbidden based on the type of interaction involved.

Quark Composition of Hadrons

Understanding the quark constitution of hadrons is essential for determining their strangeness quantum numbers. Since strange quarks carry a defined strangeness, identifying whether particles contain strange or anti-strange quarks helps in calculating the overall strangeness of a system and in checking its conservation across interactions.

Strangeness Quantum Number

Strangeness is a quantum number assigned to hadrons based on the number and type of strange quarks they contain. It is an intrinsic property used to classify particles and plays a crucial role in determining whether a reaction is allowed under the conservation rules of the strong and electromagnetic interactions.

Conservation Laws in Particle Physics

Conservation laws, such as those for charge, baryon number, and strangeness, are fundamental principles that must be satisfied in particle interactions. In the context of strong and electromagnetic interactions, the total strangeness before and after a reaction must be the same, which restricts the possible outcomes of particle processes.

Transcript

00:02 For the following reactions, we are asked if the law of conservation of strangeness is violated or not.

00:09 So if the conservation of strangeness is not violated, the strangeness number on the left side of the equation, the products, is going to be the same as the strangest number on the right side of the equation, the reactants.

00:22 So to do this, let's see if these equations balance.

00:25 If they do, i will put a red checkmark next to it, meaning the law of conservation is followed.

00:30 If they do not, i will put a red x next to it, meaning the law of conservation is not followed.

00:37 Okay, so let's go ahead and begin.

00:40 So the first one is a proton where a proton has a strangest number of zero plus a neutron, which also has a strangest number of zero.

00:55 This is being set equal to a proton, which has a strangest number of zero, plus a proton, again, zero.

01:02 Plus a negative pion.

01:08 A negative pion has a strangeness number of zero.

01:14 So this works.

01:17 We can put a red check next to it.

01:21 Next, moving on, we have a proton, zero, plus a proton equal to a proton plus a proton plus a proton, plus a negative kion.

01:39 A negative kion has a strangeness number of negative 1.