# In String Theory, can some particles contains multiple strings? [closed]

According to String Theory, can a particle consist of more than one string? I can visualize elementary particles, like leptons, being composed of a single string. But what about composite particles, such as hadrons, that are composed of quarks? Does a single string reside in each quark? Baryons, for instance, contain three quarks. So would a proton, or neutron, consist of three strings? And what about the gluons that mediate the strong nuclear force and quantum Chromodynamic force, that bind the nucleons together? Are they made of a string? Can virtual particles contain a string?

## closed as unclear what you're asking by ACuriousMind♦, CuriousOne, honeste_vivere, Gert, knzhouJun 9 '16 at 20:17

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• Particles do not "consist of strings" in string theory, neither do they "contain" them. I'm not sure what this question is asking. – ACuriousMind Jun 6 '16 at 10:22
• String theory also has branes. A common model of quarks is that there is a stack of flavor branes extending throughout space, and another stack of color branes also extending throughout space, and e.g. a red up quark is a string between a point on the red color brane and a nearby point on the up flavor brane. Meanwhile a proton is a localized brane connected by two strings to the up brane and one string to the down brane. Gluons are strings between color branes, mesons are strings between flavor branes. – Mitchell Porter Jun 10 '16 at 12:58

## 3 Answers

While writers like Briane Green do a generally laudable job of trying to explain string theory at a popular level you need to appreciate that this always involves gross simplifications. The reality is that string theory is horrifically more complicated than the pop science explanation suggests. To properly explain how particles arise in string theory is simply impossible without putting in the years of study necessary to properly understand the theory. The closest we can get is probably the idea that particles are vibrations of the strings, though even this isn't actually true.

So particles can't contain multiple strings because particles aren't made of strings.

Virtual particles are a mathematical device used to do calculations in a theory called quantum field theory, so it doesn't make sense to ask what virtual particles are made of.

In physics, string theory is a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects called strings. It describes how these strings propagate through space and interact with each other. On distance scales larger than the string scale, a string looks just like an ordinary particle, with its mass, charge, and other properties determined by the vibrational state of the string.

Now to your questions.

Does a single string reside in each quark?

It is the quark that resides on the string. Each particle is a specific vibration on the string. So each quark needs to be modeled with a string vibrating at that quark's quantum numbers.

Baryons, for instance, contain three quarks. So would a proton, or neutron, consist of three strings?

Yes, plus all the rest of the soup .

it becomes a soup of vibrating strings with the specific vibrations of the exchanged particles

And what about the gluons that mediate the strong nuclear force and quantum Chromodynamic force, that bind the nucleons together? Are they made of a string?

Yes, they are specific vibrations on a string.

Can virtual particles contain a string?

Again cart before the horse. Virtual particles are modeled with virtual strings, i.e. their quantum numbers etc are represented as specific vibrations on a virtual string. Virtual means off mass shell.

A beginning on the difficult concept of strings in describing elementary particles can be found here. An excerpt from the original link:

• Which type of string are you describing here? – CuriousOne Jun 6 '16 at 8:13
• @CuriousOne I have given a link that elaborates. Am just answering the simple questions. – anna v Jun 6 '16 at 8:52

Of course they can. Some particles arent elementary, imagine Glueballs Neutrons, Protons, they all conclude other particles. But an elementary particle (electron, quark, so on..) are described by one single string.

It is also important, what particles you are talking about, because there exist open and closed strings, which all have other mathematical definitions.

• ...the muon is an elementary particle. – ACuriousMind Jun 6 '16 at 14:00
• Yeah, you are right, that was my mistake, of course it is. – Physics Guy Jun 6 '16 at 15:23
• Write an "@ACuriousMind" into your answer-comment, or he won't see it. – peterh Jul 18 '16 at 2:14