r/Physics • u/Mr_Dr_IPA • 4d ago
Help understanding tensor bosons
I'm not very knowledgeable on math or physics, but I do like to learn about quantum particles and behaviors casually, how ever I can. I have trouble understanding how a tensor boson would behave, while I already have a somewhat decent idea of how scalar and vector bosons behave (in a simplified way at least). I understand that vector bosons can be transferred from one particle to another, which I assume has to do with them being vectors, and that scalar bosons kind of "stick around" a single area or particle, assumedly related to scalar quantities being singilar points with a value. In these senses, what would a tensor boson (or more specifically, spin-2 tensor boson) act like?
I have tried a lot to look for resources that explain to me simply what tensor bosons are like, but I haven't found anything that gives me any solid idea. I know gravitons are theorized to be spin-2 tensor bosons. I know spin-2 that means it would take only a rotation of 180° to return to its original state (don't know what relevance that has to anything though). I know that spin-2 particles can have 5 spin states: 2, 1, 0, -1, and -2. But I don't know how to visualize the effects that a spin-2 tensor boson (virtual or real) would have on other particles. That's something I'm very interested in knowing.
My understanding of boson behavior comes from learning about the elementary bosons (gluon, photon, higgs, etc), but I'm not really sure how accurate those behaviors are for composite bosons (mesons), so forgive me if what I said doesn't fully make sense.
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u/rcn5440 4d ago
Tensor is a generic term for scalar, vector, array etc. Thus, I believe it was logical to use the term tensor boson for spin-2 particles. How to visualize tensor - simple, like a 3D grid. So for example, if you imagine a 3D grid around the earth then gravity’s effect would be represented by the grid being pinched at the center and all the grid lines stretched accordingly. Thus, a tensor boson has properties that affects a 3D grid. Note, I am not an expert, though.
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u/liccxolydian 3d ago
You are mixing up the ML/CS definition of "tensor" with how everyone else uses that term.
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u/Dihedralman 4d ago
It has to do with representations of quantum properties.
Scalar, vector, and tensors are all mathematical objects. Scalars and vectors can be thought of as low rank tensors. Scalars are defined by a single number. Vectors multiple numbers. A second order tensor relies on a matrix meaning those numbers vary with other numbers at the same time. The stress tensor is an example, where you have xx,yy,zz, for compression and tension and xy etc for shear forces.
Quantum field theory represents particles with a series of probability fields that multiply key quantities together including spin.
A scalar means no rotation is possible. Remember that spin can exist in x, y, and z. A scalar boson has no spin. There is no transformation that can be done. A scalar is attached to the equation from spin. You will always measure spin 0 and it doesn't change under transformation.
A vector boson takes the values -1,0,1 on a given axis. It can potentially take multiple values. You multiply it by a single lorentz matrix to represent rotation. That tells you how spin will mix along every axis. Why? Because a 2 spin field requires the outer product of two vector matrixes. If you run quantum step up operation you find this. Think of a compound particle of two bosons and adding together the possible momentum combinations. That represents a 2 state boson. To rotate those representations you need two matrices.
Spin two requires two lorentz matrixes increasing the number of parameters and making complex relationships.
I don't quite know what you mean by stick around with scalar bosons. It changes the degeneracy of the state and how a condensation would form. There are simpler interactions to consider. No spin contributions to consider in scattering for example.