kb/data/en.wikipedia.org/wiki/Glossary_of_string_theory-0.md

title	chunk	source	category	tags	date_saved	instance
Glossary of string theory	1/5	https://en.wikipedia.org/wiki/Glossary_of_string_theory	reference	science, encyclopedia	2026-05-05T07:51:24.096924+00:00	kb-cron

This page is a glossary of terms in string theory, including related areas such as supergravity, supersymmetry, and high energy physics.

== Conventions ==

-bein A suffix indicating a frame, where the first part is a German word indicating the dimension (as in zweibein, vierbein, and so on).

-ino The superpartners of bosons are often denoted by the suffix -ino; for example, photon/photino.

s- The superpartners of fermions are often denoted by adding s- at the beginning; for example, quark/squark.

== αβγ ==

α

1. Fine-structure constant

2. Regge slope, or inverse of the string tension How are these related? There is only one dimensional constant in string theory, and that is the inverse string tension

     α
   
       ′
   

   {\displaystyle \alpha ^{\prime }}

with units of area. Sometimes

      α
      
        ′
      
    
  

{\displaystyle \alpha ^{\prime }}

is therefore replaced by a length

      l
      
        s
      
    
    =
    
      
        
          α
          
            ′
          
        
      
    
  

{\displaystyle l_{s}={\sqrt {\alpha ^{\prime }}}}

. The string tension is mostly defined as the fraction

        1
        
          2
          π
          
            α
            
              ′
            
          
        
      
    
    .
  

{\displaystyle {\frac {1}{2\pi \alpha ^{\prime }}}.}

Tension is energy or work per unit length. In natural units

    c
    =
    1
  

{\displaystyle c=1}

and

    ℏ
    =
    1
  

{\displaystyle \hbar =1}

, and hence

      α
      
        ′
      
    
  

{\displaystyle \alpha ^{\prime }}

has dimension of length/energy or length/mass. Since

    ℏ
  

{\displaystyle \hbar }

has the dimension of action, i.e. momentum times length, it follows that in natural units mass =1/length, and so

      α
      
        ′
      
    
  

{\displaystyle \alpha ^{\prime }}

has the unit of area. The slope

      α
      
        ′
      
    
  

{\displaystyle \alpha ^{\prime }}

of a Regge trajectory

    α
    (
    
      M
      
        2
      
    
    )
  

{\displaystyle \alpha (M^{2})}

in Regge theory is the derivative of spin

    S
  

{\displaystyle S}

or angular momentum with respect to mass-squared, i.e.

          d
          S
        
        
          d
          
            M
            
              2
            
          
        
      
    
    .
  

{\displaystyle {\frac {dS}{dM^{2}}}.}

Since angular momentum is moment of momentum

    p
  

{\displaystyle p}

, i.e. length times mass with

    c
    =
    1
  

{\displaystyle c=1}

,

    S
  

{\displaystyle S}

is dimensionless in natural units, and

      α
      
        ′
      
    
  

{\displaystyle \alpha ^{\prime }}

has units of

    1
    
      /
    
    
      M
      
        2
      
    
  

{\displaystyle 1/M^{2}}

or area like the inverse string tension.

3. A Fourier coefficient of a spacetime coordinate.
4. αs is the strong coupling constant

β

1. One of the two conformal superghost fields β, γ used in the BRST quantization of the superstring
2. Euler beta function
3. Beta function describing the change of coupling constant under the renormalization group flow

γ

1. Dirac matrix
2. One of the two conformal superghost fields β, γ used in the BRST quantization of the superstring
3. World-sheet metric γab(σ,τ)
4. Photon
5. Euler constant .57721...

Γ

1. Lattice
2. Euler Gamma function
3. Dirac matrix
4. Width of some scattering process

δ

1. Kronecker delta function
2. An infinitesimal change in something; for example δL is an infinitesimal change in L

Δ

1. Propagator
2. Delta baryon, a baryon with 3 light quarks and isospin 3/2
3. Laplace operator in Euclidean space or more generally a Riemannian manifold

ε

1. Small positive real number
2. Antisymmetric tensor

η

1. Flat Lorentzian metric on spacetime
2. Dedekind eta function, a weight 1/2 modular form
3. Eta meson, a neutral flavor meson with PC = –+

θ

1. Theta function
2. θc is the Cabbibo angle
3. θw is the Weinberg angle, also called the weak mixing angle

Λ

1. Cosmological constant
2. Large energy or large mass cutoff in regularization
3. Lambda baryon, a baryon with 2 light quarks and isospin 0

μ

1. Renormalization scale, with the dimensions of mass
2. Muon

ν Neutrino

Ξ

1. Xi baryon, a baryon with 1 light quark

π

1. 3.14159...
2. Pion

Π The momentum density conjugate to X

ρ Rho meson, a light meson with PC = ––

σ

1. Spacelike coordinate on the world-sheet
2. Scattering cross section
3. Pauli matrix
4. See #sigma model

Σ

1. Sigma baryon, a baryon with 2 light quarks and isospin 1

τ

1. Timelike coordinate on the world-sheet
2. Element of the upper half plane
3. Tauon

Υ Upsilon meson (bb)

φ Scalar field

χ Neutral-flavor heavy meson with PC = ++

ψ

1. Spinor field
2. Psi meson (cc)

Ω

1. Density of something in the universe; for example, Ων is the neutrino density
2. Omega baryon, a baryon with no light quarks

== !$@ ==

' (prime) X′ means ∂X/∂σ.

dot above letter Ẋ means ∂X/∂τ

∇

1. A covariant derivative
2. The del operator.

□ The D'Alembert operator, or non-Euclidean Laplacian.

[,] A commutator: [A,B] = AB–BA.

{,} An anticommutator: {A,B} = AB+BA.

== A ==

A

1. A connection 1-form
2. Short for antiperiodic, a boundary condition on strings.
3. Short for axial vector
4. An asymmetry

action A function S on the space of fields given (formally) by the integral of the Lagrangian density over spacetime, whose stationary points are the solutions of the equations of motion. ADE Refers to the ADE classification (An,Dn, E6, E7, E8) of simply laced Dynkin diagrams, and to several related classifications of Lie algebras, singularities and so on. ADHM Initials of Atiyah, Drinfeld, Hitchin, and Manin, as in the ADHM construction of instantons.

ADM Initials of Arnowitt, Deser, and Misner, as in ADM energy, a way of defining the global energy in an asymptotically flat spacetime, or ADM decomposition of a metric, or ADM formalism.

AdS Anti-de Sitter, as in anti-de Sitter space, a Lorentzian analogue of hyperbolic space

AdS/CFT Anti-de Sitter/conformal field theory, especially the AdS/CFT correspondence.

ALE Asymptotically locally Euclidean

ALEPH ALEPH experiment at LEP

AMSB Anomaly mediation supersymmetry breaking

ASD Anti self-dual (connection)

ATLAS The ATLAS experiment at CERN, a particle detector.

axino A hypothetical supersymmetric partner of an axion. axion A hypothetical scalar particle whose mass arises from a coupling rather than from a mass term in the Lagrangian, used to resolve the strong CP problem.

== B ==

b

1. One of the two conformal ghost fields b, c used in the BRST quantization of the bosonic string.
2. A bottom quark.