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What is vector-like matter?

  1. May 25, 2010 #1
    What is "vector-like" matter?

    Hi,
    can someone please tell me what vector-like matter is?
    Best,
    meha
     
  2. jcsd
  3. May 25, 2010 #2

    tom.stoer

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    Re: What is "vector-like" matter?

    can you tell us where you found the term "vector-like matter"?
     
  4. May 25, 2010 #3
    Re: What is "vector-like" matter?

    Sure, one place I encountered it is here:
    http://arxiv.org/abs/1001.1129
     
  5. May 26, 2010 #4

    tom.stoer

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    Re: What is "vector-like" matter?

    Unfortunately they do not write down the kinetic part of the Lagrangian.

    I suspected that it has something to do with spin, but w/o the Lagrangian it's hard to tell. In addition they talk about a scalar superpartner, but the superpartner to a spin-1object is not spin-0.
     
  6. May 26, 2010 #5
    Re: What is "vector-like" matter?

    It looks like they're using the term to imply that the new (fermionic) matter has vector-like couplings to all standard model gauge fields. This is to be contrasted with ordinary standard model fermions, which have chiral SU(2)xU(1) couplings.
     
  7. May 26, 2010 #6
    Re: What is "vector-like" matter?

    Thanks. According to the reference hep-th/9903387 vector-like is used synonymously with non-chiral. Which means that left and right components transform differently under SU(2) x U(1). But what if these groups are not present? What would be the distinction between chiral and non-chiral matter for SU(5) or SO(10)?
     
  8. May 27, 2010 #7

    tom.stoer

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    Re: What is "vector-like" matter?

    Just to make sure: "chiral" means that there is a gamma matrix projector in the Dirac kinetic term, whereas "vector" means it looks like in QED w/o such a projector?
     
  9. May 29, 2010 #8
    Re: What is "vector-like" matter?

    Thanks for all your thoughts.
     
  10. May 29, 2010 #9

    arivero

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    Re: What is "vector-like" matter?

    Probabli the best translation is tom's "like in QED".

    Historically, the problem of GUT models has been to avoid vector-like interactions. Actually, vector-like *matter* is a misnomer; it refers to *interactions*
     
  11. May 29, 2010 #10
    Re: What is "vector-like" matter?

    Now I am confused. In susy theories there are chiral superfields as well as vector superfields, completely independent of interactions. (http://en.wikipedia.org/wiki/Supersymmetric_gauge_theory). Chiral fields are defined by [tex]\bar{D} \Phi=0[/tex]. Vector fields one the other hand are identical to their hermitian adjoints [tex]V = V^{\dagger}[/tex]. Am I intermingling different concepts here?
     
  12. May 30, 2010 #11

    tom.stoer

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    Re: What is "vector-like" matter?

    Yes, the concepts are different and the name vector-like matter is misleading.

    As far as we understand the paper the situation is as follows: one uses spinors (!) to construct either bilinear vectors (like the el.-mag. current from the fermion field) or bilinear axial vector (like the left-handed neutrino current in el.-weak theory). The currents are coupled to other fields, in these examples the photon field or the Z- and W-field.

    If the current is a vector, the matter is called vector-like even if the matter field itself is a spinor. (this is my interpretation of the discussion)
     
  13. May 30, 2010 #12
    Re: What is "vector-like" matter?

    Strictly, the neutrino current is left chiral, not axial. A left chiral current is vector minus axial vector (or V-A); and a right chiral current is V+A.
     
  14. May 30, 2010 #13

    tom.stoer

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    Re: What is "vector-like" matter?

    You are right.
     
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