# Is it possible for s/anti-s quarks to become down/anti-down quarks via strong force?

## Main Question or Discussion Point

I'm working on a problem involving decay of a 2 strange/2 anti-strange tetraquark particle.
4 sample decay diagrams are given and I am to describe them and choose which is most prevalent.

In on diagram, two of the strange/anti-strange quarks become two down/anti-down quarks via gluon through strong force interaction, which then go on to form one 0-Kaon and one anti-0-Kaon.

Can someone please explain what exactly is occurring through the strong force interaction? Aka how are the strange quarks becoming their down counterparts?

MUCH APPRECIATED!

## Answers and Replies

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The strange quark and anti-quark are "annihilating" each other, and the "virtual" gluon resulting from the annihilation is then "pair-producing" a down quark and anti-quark. A similar process can proceed via a virtual photon through the electromagnetic interaction, if that is more familiar.

The strange quark and anti-quark are "annihilating" each other, and the "virtual" gluon resulting from the annihilation is then "pair-producing" a down quark and anti-quark. A similar process can proceed via a virtual photon through the electromagnetic interaction, if that is more familiar.
Awesome, thanks.

Also, what about if a strange and anti-strange quark, through the strong force (this one involves two gluons), formed an anti-up quark and up quark, which then combined to form a negative and positive Kaon?

I suppose the reason I'm confused is that I don't understand how an up and anti-up quark seemingly appear from nowhere, while the strange and anti-strange quarks still go on existing to combine with them to form the Kaons. I feel like I'm missing some major piece of information necessary for understanding this.

Thanks again!

Also, what about if a strange and anti-strange quark, through the strong force (this one involves two gluons), formed an anti-up quark and up quark, which then combined to form a negative and positive Kaon?

I suppose the reason I'm confused is that I don't understand how an up and anti-up quark seemingly appear from nowhere, while the strange and anti-strange quarks still go on existing to combine with them to form the Kaons. I feel like I'm missing some major piece of information necessary for understanding this.
If I understood your original post correctly, you have two pairs of strange quarks and antiquarks (four particles total making up the tetraquark). One pair of strange quark and antiquark annihilates, while the other pair "go[es] on existing" to form the kaons. The gluon or photon formed by the annihilating pair should be able to produce either an up quark--antiquark pair or a down quark--antiquark pair.

I find it harder to visualize any process involving two gluons... just make sure that all the quark--antiquark--gluon vertices in the diagram involve quarks and antiquarks of the same "flavor" (that is, either up--antiup, down--antidown or strange--antistrange).