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 ${\displaystyle \alpha ^{\prime ))$ with units of area. Sometimes ${\displaystyle \alpha ^{\prime ))$ is therefore replaced by a length ${\displaystyle l_{s}={\sqrt {\alpha ^{\prime ))))$. The string tension is mostly defined as the fraction

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

Tension is energy or work per unit length. In natural units ${\displaystyle c=1}$ and ${\displaystyle \hbar =1}$, and hence ${\displaystyle \alpha ^{\prime ))$ has dimension of length/energy or length/mass. Since ${\displaystyle \hbar }$ has the dimension of action, i.e. momentum times length, it follows that in natural units mass =1/length, and so ${\displaystyle \alpha ^{\prime ))$ has the unit of area. The slope ${\displaystyle \alpha ^{\prime ))$ of a Regge trajectory ${\displaystyle \alpha (M^{2})}$ in Regge theory is the derivative of spin ${\displaystyle S}$ or angular momentum with respect to mass-squared, i.e.

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

Since angular momentum is moment of momentum ${\displaystyle p}$, i.e. length times mass with ${\displaystyle c=1}$, ${\displaystyle S}$ is dimensionless in natural units, and ${\displaystyle \alpha ^{\prime ))$ has units of ${\displaystyle 1/M^{2))$ or area like the inverse string tension.

3.  A Fourier coefficient of a spacetime coordinate.

4.  α_s 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 γ_ab(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.  θ_c is the Cabbibo angle

3.  θ_w 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, Ω_ν 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

Main article: action (physics)

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

Main article: ADE classification

Refers to the ADE classification (A_n,D_n, 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

Main article: Axino

A hypothetical supersymmetric partner of an axion.

axion

Main article: 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.

B

1.  Baryon number

2.  Short for boson.

3.  Short for baryon.

4.  Short for backward;for example, σ_B is the cross section for backward scattering.

5.  a bottom meson.

BAO

Baryon acoustic oscillation

BB

Big Bang

BBN

Big Bang nucleosynthesis

bino

Main article: gaugino

A hypothetical supersymmetric partner of the gauge field corresponding to weak hypercharge.

BIon

A BPS solution representing an infinite string ending on a D-brane. Named after the Born–Infeld action.

BPS

Main article: BPS state

A state related to the Bogomol'nyi–Prasad–Sommerfield bound.

BR

Branching ratio

BRS

BRST quantization

Main article: BRST quantization

Short for Becchi, Rouet, Stora and Tyutin, who introduced the BRST quantization of gauge theories.

brane

Short for membrane. a higher-dimensional manifold moving in spacetime. See also p-brane, D-brane.

BTZ

Initials of Bañados–Teitelboim–Zanelli, as in BTZ black hole, a black hole in 2+1-dimensional gravity.

BV

Batalin–Vilkovisky, as in Batalin–Vilkovisky formalism.

C

c

1.  The speed of light, when not using units where this is 1.

2.  A central charge of the Virasoro algebra or similar algebra.

3.  One of the two conformal ghost fields b, c used in the BRST quantization of the bosonic string.

4.  A Chern class.

5.  A charm quark.

C

1.  Charge, especially the charge symmetry.

Calabi–Yau

Main article: Calabi–Yau manifold

A Kähler manifold with vanishing Ricci curvature, used for compactifying string theories.

CAR

Canonical anticommutation relations

CBR

Cosmic background radiation

CC

1.  Charged current (weak interaction).

2.  Complex conjugate

3.  Compatibility condition

CCR

Canonical commutation relation

CCR and CAR algebras

CDF

Collider Detector at Fermilab

CDM

Cold dark matter

CERN

Conseil Européen pour la Recherche Nucléaire

chargino

Main article: chargino

A hypothetical charged supersymmetric partner of a gauge boson.

Chern–Simons

1.  

Main article: Chern–Simons theory

2.  

Main article: Chern–Simons form

chiral

1.  Not invariant under the parity symmetry. The word comes from the Greek χειρ meaning "hand"; the terms "left-handed" and "right-handed" are often used to describe chiral objects.

Main article: Chirality (physics)

2.  A chiral multiplet is a type of supermutliplet of a supersymmetry algebra.

CIPT

Contour improved perturbation theory

CKG

Short for conformal Killing group.

CKM

The Cabibbo–Kobayashi–Maskawa matrix.

CKS

Short for conformal Killing spinor.

CKV

Short for conformal Killing vector.

CFT

Conformal field theory

Chan–Paton

A Chan–Paton charge is a degree of freedom carried by an open string on its endpoints.

cl

1.  Short for classical (for example, S_cl is the classical action).

2.  CL is short for confidence limit.

closed

A closed string is one with no ends.

CM

Center of mass (frame)

CMB

CMBR

Cosmic microwave background radiation

CMS

1.  The Compact Muon Solenoid at CERN, a particle detector.

2.  Short for the Center-of-Momentum System, a coordinate system where the total momentum is 0.

compactification

A method for reducing the apparent dimension of spacetime by wrapping the string around a compact manifold.

cosmological constant

Main article: cosmological constant

The constant term of the Lagrangian, inducing a term in the action proportional to the volume of spacetime

CP

Short for Charge–Parity, as in CP symmetry.

CPC

Short for Charge–Parity conservation.

CPT

Short for Charge–Parity–Time, as in CPT symmetry or CPT theorem.

CPV

Short for Charge–Parity violation.

critical

The critical dimension is the spacetime dimension in which a string or superstring theory is consistent; usually 26 for string theories and 10 for superstring theories.

CVC

Conserved vector current.

CY

Short for Calabi–Yau, as in Calabi–Yau manifold, a Ricci-flat Kähler manifold, often used for compactifying superstring theories.

D

d

1.  The exterior derivative of a form.

2.  A down quark.

3.  The dimension of spacetime.

D

1.  Short for Dirichlet, as in D-brane

2.  The dimension of spacetime

3.  A connection or differential operator

4.  A Dynkin diagram of an orthogonal group in even dimensions.

5.  A charmed meson.

D0

Main article: DØ experiment

D-brane

Dp-brane

Main article: D-brane

Short for Dirichlet (mem)brane, a submanifold (of dimension p+1) on which the ends of strings are constrained to lie, so that the strings satisfy Dirichlet boundary conditions.

D-string

A D1-brane

DBI

Short for Dirac–Born–Infeld, as in the DBI action, an action based on the Born–Infeld action, a modification of the Maxwell action of electrodynamics.

DDF

Initials of Del Guidice, Di Vecchia, and Fubini, as in Del Guidice–Di Vecchia–Fubini operator, operators generating an oscillator algebra.

DELPHI

DELPHI experiment at LEP.

DESY

Deutsches Elektronen-Synchrotron

DGLAP

Initials of Dokshitzer–Gribov–Lipatov–Altarelli–Parisi who introduced the DGLAP evolution equation in QCD.

Diff

Diffeomorphism or diffeomorphism group.

dilatino

Main article: dilatino

A supersymmetric partner of the dilaton.

dilaton

Main article: dilaton

A massless scalar particle, related to dilations of spacetime.

Dirichlet

Dirichlet boundary conditions on an open string say that the ends of the string are fixed (often lying on a D-brane).

DIS

Deep inelastic scattering

DLCQ

Discrete light-cone quantization

DM

Dark matter

DØ

Main article: DØ experiment

Dp-brane

Main article: D-brane

Short for Dirichlet (mem)brane, a submanifold (of dimension p+1) on which the ends of strings are constrained to lie, so that the strings satisfy Dirichlet boundary conditions.

DR

1.  Short for dimensional regularization.

2.  Short for dimensional reduction, a way of constructing theories from simpler theories in higher dimensions, sometimes by making fields invariant under some spacelike translations.

dS

de Sitter, as in de Sitter space, a Lorentzian analogue of a sphere

dS/CFT

de Sitter/conformal field theory, especially the dS/CFT correspondence.

dual resonance model

Main article: Dual resonance model

An early precursor of string theory.

duality

Main article: String duality

A hidden connection between two different theories, such as S-duality, T-duality, U-duality, mysterious duality.

DY

Initials of Drell–Yan, as in DY process.

dyon

Main article: Dyon

A hypothetical particle with both electrical and magnetic charge.

E

e

1.  Euler's constant

2.  A frame

3.  An electron

E

Energy

E6

Main article: E6 (mathematics)

E₆ is the exceptional Lie algebra of rank 6 and dimension 78.

E7

Main article: E7 (mathematics)

E₇ the exceptional Lie algebra of rank 7 and dimension 133.

E8

Main article: E8 (mathematics)

E₈ the exceptional Lie algebra of rank 8 and dimension 248.

eff

Short for effective (field theory).

EFT

Effective field theory, a low-energy approximation to a theory.

einbein

A frame in 1 dimension

elfbein

A frame in 11 dimensions

energy–momentum tensor

Main article: Energy–momentum tensor

A symmetric tensor T (also called the stress-energy tensor) describing the variation of the action under changes in the metric, whose components give the local energy, momentum and stress densities. In flat spacetimes it can also be given by combining the Noether currents of the translation symmetries.

EWSB

Electro-weak symmetry breaking.

F

F

1.  A curvature form of a connection

2.  The world-sheet fermion number.

3.  Short for fermion

3.  Short for forward;for example, σ_F is the cross section for backward scattering.

F4

Main article: F4 (mathematics)

F₄ is the exceptional Lie algebra of rank 4 and dimension 52.

FCNC

Flavor-changing neutral current.

field

A section of a fiber bundle

FOPT

Fixed-order perturbation theory.

F-string

Fundamental string

F-theory

Main article: F-theory

Possibly an abbreviation of father theory. A 12-dimensional string theory introduced by Vafa.

FRW

Friedman–Robertson–Walker metric on spacetime

G

g

1.  A metric

2.  A coupling constant

3.  The genus of a Riemann surface.

4.  A gluon.

G

1.  Newton's gravitational constant, sometimes written G_N.

2.  The Fermi coupling constant for weak interactions, sometimes written G_F.

3.  G_n is an odd element of the Ramond or Neveu–Schwarz superalgebra.

G2

Main article: G2 (mathematics)

The exceptional Lie algebra of rank 2 and dimension 14, or a G2 manifold with G₂ holonomy.

gaugino

A spin 1/2 supersymmetric partner of a gauge boson.

gh

Abbreviation for ghost; for example, S_gh is the ghost action.

ghost

A vector of negative norm.

GKO

Short for Goddard–Kent–Olive. The GKO construction, also called the coset construction, is a way of constructing unitary discrete series representations of the Virasoro algebra.

GL

A general linear group.

gluino

Main article: gluino

A hypothetical supersymmetric partner of a gluon.

gluon

Main article: gluon

A gauge boson associated with the strong force.

GMSB

Gauge mediated supersymmetry breaking.

goldstino

Main article: goldstino

A massless spin 1/2 particle associated with spontaneous breakdown of supersymmetry, analogous to the Goldstone boson.

GR

General relativity

graviton

Main article: graviton

A conjectural spin 2 massless particle responsible for gravity.

gravitino

Main article: gravitino

A supersymmetric partner of the graviton.

Green

Named for Michael Green.

GS

Green–Schwarz formalism, a way of incorporating supersymmetry into string theory that is supersymmetric in 10-dimensional spacetime.

GSO

Short for Ferdinando Gliozzi, Joël Scherk, and David A. Olive, as in the GSO projection, a projection in superstring theory that eliminates tachyons.

GSW

The 2-volume work on superstring theory by Green, Schwarz, and Witten.

GUT

Grand unified theory, a hypothetical theory unifying the strong and electroweak forces.

GWS

Glashow–Weinberg–Salem theory of the electroweak force.

GZK

The Greisen–Zatsepin–Kuzmin limit on the energy of cosmic background radiation from distant sources.

H

h

1.  The weight of a field (for example, its eigenvalue for L₀).

2.  Hermitian; for example, h.c. stands form hermitian conjugate.

H

1.  The Hamiltonian.

2.  The Higgs boson.

3.  The Hubble constant.

Haag–Łopuszański–Sohnius theorem

Main article: Haag–Łopuszański–Sohnius theorem

A theorem describing the possible supersymmetries of a quantum field theory, generalizing the Coleman–Mandula theorem.

Hagedorn temperature

Main article: Hagedorn temperature

The temperature above which the partition function diverges due to the exponentially increasing number of string states.

h.c.

hc

Hermitian conjugate

HCMS

Hadronic center of mass (frame)

HDM

Higgs doublet model

HE

Short for heterotic-E²
₈, a heterotic string theory based on the group E²
₈.

helicity

Main article: Helicity (particle physics)

The projection of the spin of a massless particle in the direction of its momentum.

HERA

Hadron Elektron Ring Anlage

heterotic

Main article: heterotic string

Named after the Greek word heterosis, meaning hybrid vigour. A hybrid of bosonic string theory and superstring theory, introduced by David Gross, Jeffrey Harvey, Emil Martinec, and Ryan Rohm in 1985.

Higgs boson

Main article: Higgs boson

A massive scalar particle related to the spontaneous symmetry breaking mechanism in the electroweak theory.

Higgsino

Main article: Higgsino

A hypothetical supersymmetric partner of a Higgs boson.

HO

Short for heterotic-orthogonal, a heterotic string theory based on the orthogonal group O₃₂(R).

holographic principle

Main article: Holographic principle

HQET

Main article: Heavy quark effective theory

Hyperkähler

Hyperkaehler

Main article: Hyperkähler manifold

A Riemannian manifold with holonomy contained in the compact form of the symplectic group.

Hypermultiplet

Main article: Hypermultiplet

A type of supermultiplet (representation) of an extended supersymmetry algebra.

I

i

√–1

I

Isospin.

IGM

Intergalactic medium

inflation

Main article: Inflation (cosmology)

A hypothetical very rapid increase in the size of the very early universe.

instanton

Main article: Instanton

A self-dual or anti-self-dual connection in a principal bundle over a four-dimensional Riemannian manifold.

int

Short for interaction; for example, H_int might be an interaction Hamiltonian.

inv

Short for invisible; for example, Γ_inv is the width for invisible decays (those unobseverd by an experiment).

J

J

1.  A current

2.  A source

3.  Spin.

K

k

A momentum

K

A kaon (a strange meson).

K3

Main article: K3 surface

A simply connected compact complex surface of Kodaira dimension 0

K-theory

Main articles: K-theory and K-theory (physics)

A cohomology theory based on vector bundles.

Kac–Moody algebra

Main article: Kac–Moody algebra

A central extension of a loop algebra.

Kähler

Kaehler

Named after Erich Kähler

1.  A Kähler manifold is a complex manifold with a compatible Riemannian metric.

2.  A Kähler metric is the metric on a Kähler manifold.

3.  A Kähler potential is a function of superfields used to construct a Lagrangian.

Kalb–Ramond field

Main article: Kalb–Ramond field

KK

Kaluza–Klein

KM

1.  The Kobayashi–Maskawa mechanism for CP violation.

2.  Kac–Moody algebra.

KZ

Initials of Knizhnik and Zamolodchikov, as in KZ equation, a differential equation related to the primary fields of a current algebra.

L

L

1.  A Lagrangian

2.  L_n is an element of the Virasoro algebra.

3.  An abbreviation for left (moving modes).

4.  Lepton number

5.  Short for lepton

L3

L3 experiment at LEP.

Lagrangian (field theory)

Main article: Lagrangian (field theory)

A function on the jet space of a fiber bundle.

landscape

Main article: String theory landscape

The (conjectural) moduli space of all (vacuums of) string theories.

LEP

The Large Electron–Positron Collider at CERN.

lepton

Main article: lepton

An elementary particle of spin 1/2 that is unaffected by the strong force.

LH

Left-handed

LHC

The large hadron collider at CERN.

little string theory

Main article: Little string theory

LL

Double logarithmic

LO

Leading order (term)

LQG

Loop quantum gravity

LQC

Loop quantum cosmology

LSP

Abbreviation for lightest supersymmetric particle.

LSS

Large scale structure (of the universe).

M

m

A mass of a fermion. For example, m_t is the mass of the top quark t.

M

The mass of a boson; for example, M_Z is the mass of the Z-boson.

Majorana fermion

Majorana spinor

Main articles: Majorana fermion and Majorana spinor

A fermion or spinor with a reality condition, in spacetimes of dimension 2, 3, 4 mod 8.

Majorana–Weyl fermion

Majorana–Weyl spinor

Main articles: Majorana–Weyl fermion and Majorana–Weyl spinor

A half-spinor with a reality condition, in spacetimes of dimension 2 mod 8.

Mandelstam variable

Main article: Mandelstam variables

A sum or difference of two of the four incoming or outgoing momenta of a 2-particle interaction.

matrix theory

M(atrix) theory

Main article: Matrix string theory

One of several non-perturbative formulations of string theory or M-theory using infinite matrices.

M-brane

membrane

Main article: Membrane (M-theory)

A higher dimensional analogue of a string.

MC

Monte Carlo integration

MCG

Main article: Mapping class group

minimal model

Certain solvable conformal field theories.

Mirror symmetry (string theory)

Main article: Mirror symmetry (string theory)

A partly conjectural relation between a type IIA superstring theory compactified on a Calabi–Yau manifold and a type IIB superstring theory compactified on a different "mirror" Calabi–Yau manifold.

MLLA

Modified leading logarithm approximation.

MNS

Maki–Nakagawa–Sakata matrix for neutrino mixing

monopole

Main articles: Magnetic monopole, Dirac monopole, Wu–Yang monopole, 't Hooft–Polyakov monopole, Seiberg-Witten monopole, and Monopole (mathematics)

A hypothetical particle similar to a "magnet with only one pole".

Montonen–Olive duality

Main article: Montonen–Olive duality

An early case of S-duality.

MS

minimal subtraction (a renormalization scheme). MS is the modified minimal subtraction scheme.

MSM

Abbreviation for minimal standard model.

MSSM

Abbreviation for minimal supersymmetric standard model.

mSUGRA

Minimal model of supergravity.

M-theory

Main article: M-theory

An 11-dimensional theory introduced in the second string theory revolution to unify the 5 known superstring theories. The letter M has been said to stand for membrane, matrix, magic, mystery, monster, and so on.

MSW

Mikheyev–Smirnov–Wolfenstein effect concerning neutrino oscillations in matter.

multiplet

A linear representation of a Lie algebra or group.

A collection of elementary particles corresponding to a basis of a representation.

N

N

1.  The number of times each irreducible real spinor representation appears in the fermionic part of a supersymmetry algebra or super Minkowski space. It is often used in the description of an extended supersymmetry algebra, as in N=2 superconformal algebra and so on.

2.  A nucleon, a baryon with 3 light quarks and isospin 1/2 (such as a proton or neutron).

3.  The number of some type of particle.

Nambu–Goto action

Main article: Nambu–Goto action

An action for strings, proportional to the area of the worldsheet.

NC

Neutral current (weak interaction).

Neumann

Neumann boundary conditions on an open string say that the momentum normal to the boundary of the world-sheet is zero.

neutralino

Main article: Neutralino

A hypothetical supersymmetric partner of a gauge boson with zero charge.

Neveu

Named for André Neveu.

Neveu–Schwarz algebra

Main article: Neveu–Schwarz algebra

A supersymmetric extension of the Virasoro algebra, similar to the Ramond algebra.

NG

1.  Short for Nambu–Goto, as in Nambu–Goto action.

2.  Short for Nambu–Goldstone, as in Nambu–Goldstone boson.

NLL

Next to leading logarithmic (term).

NLO

Next to leading order (term).

NLSP

next-to-lightest sypersymmetric particle

NMSSM

Next-to-Minimal Supersymmetric Standard Model.

NNLL

Next to next to leading logarithmic (term).

NNLO

Next to next to leading order (term).

NNNLL

Next to next to next to leading logarithmic (term).

no-ghost theorem

Main article: No-ghost theorem

A theorem stating that some hermitian form is positive semidefinite, in other words has no ghosts (negative norm vectors). The name is a word-play on no-go theorem.

NR

Non-relativistic

NRQCD

Non-relativistic quantum chromodynamics

NS

Neveu–Schwarz, especially the Neveu–Schwarz algebra

NS–NS

A sector with Neveu–Schwarz conditions on left and right moving modes.

NS–R

A sector with Neveu–Schwarz conditions on left moving modes and Ramond conditions on right moving modes.

NUT

The initials of E. Newman, L. Tamburino, and T. Unti, mainly used in Taub–NUT vacuum, a solution to Einsteins' equations.

O

O

An orthogonal group

OCQ

Short for old covariant quantization

OPAL

The OPAL detector at LEP.

open

An open string is one with two ends.

OPE

operator product expansion

Main article: Operator product expansion

A description of short-distance singularities of fields.

orbifold

Main article: orbifold

Something that looks locally like a manifold quotiented by the action of a finite group.

OSp

A Lie superalgebra.

P

p

A momentum

P

1.  Parity, especially the parity symmetry.

2.  Short for periodic, a boundary condition on strings (as opposed to A for antiperiodic).

3.  Pseudoscalar (current)

4.  Momentum

5.  One of the bosonic elements of a supersymmetry algebra.

p-brane

A p+1 dimensional membrane, where p is a non-negative integer. The dimension of membranes is often given by their space dimension, which is 1 less than their full spacetime dimension.

PCAC

partially conserved axial vector current

PDF

Parton distribution function.

PDG

Particle Data Group.

photino

Main article: photino

A hypothetical supersymmetric partner of the photon.

photon

Main article: photon

The neutral spin 1 gauge boson of the electromagnetic field.

PMNS

Pontecorvo–Maki–Nakagawa–Sakata matrix for neutrino mixing

Polyakov action

Main article: Polyakov action

A modification of the Nambu–Goto action for strings that eliminates the square root.

PQ

Peccei–Quinn, as in Peccei–Quinn theory.

pQCD

PQCD

Perturbative quantum chromodynamics.

prepotential

A function used to construct the vector superfield in supersymmetric gauge theory and Seiberg–Witten theory.

primary field

A field killed by the positive weight operators of the Virasoro algebra (or similar algebra); in other words, a lowest weight vector.

Princeton string quartet

David Gross, Jeffrey Harvey, Emil Martinec, and Ryan Rohm, who introduced the heterotic string in 1985.

PSL

Projective special linear group.

Q

q

A quark.

Q

1.  The BRST operator.

2.  A charge

3.  One of the fermionic generators of a supersymmetry algebra.

quark

Main article: quark

A strongly interacting elementary particle of spin 1/2.

QCD

Main article: Quantum chromodynamics

QED

Main article: Quantum electrodynamics

R

R

1.  Short for Ramond, as in Ramond sector.

2.   A curvature tensor

Main articles: Scalar curvature, Ricci curvature, and Riemann curvature

3.  An abbreviation for right (moving modes).

4.  A radius

5.  R-symmetry is a symmetry of extended supersymmetry algebras.

Ramond

Named for Pierre Ramond.

Ramond algebra

Main article: Ramond algebra

A supersymmetric extension of the Virasoro algebra, similar to the Neveu–Schwarz algebra.

Rarita–Schwinger

Main articles: Rarita–Schwinger equation and Rarita–Schwinger field

Refers to spin 3/2 fermions.

Regge

1.  Physicist Tullio Regge.

2.  Regge trajectory: the squared mass of a hadronic resonance is roughly linear in the spin, with the constant of proportionality called the Regge slope.

revolution

Any new idea in string theory. In particular the first superstring revolution refers to the discoveries in the mid 1980s such as the cancellation of gravitational anomalies and the heterotic string, and the second superstring revolution refers to the discoveries in the mid 1990s, such as D-branes, M-theory, and matrix theory and the AdS/CFT correspondence.

RG

Renormalization group.

RGE

Renormalization group equation.

RH

Right-handed

R–NS

A sector with Ramond conditions on left moving modes and Neveu–Schwarz conditions on right moving modes.

RNS

Ramond–Neveu–Schwarz, as in RNS formalism, a way of incorporating supersymmetry into string theory that is supersymmetric on the world sheet.

R-parity

Main article: R-parity

A Z₂ symmetry of supersymmetric models.

R-R

Short for Ramond–Ramond sector

S

s

1.  A strange quark.

2.  A Mandelstam variable

S

1.  An action

2.  A scattering matrix.

3.  The transformation τ → –1/τ of the upper half plane

4.  Scalar (current)

5.  Short for super or supersymmetric

S-brane

A brane similar to a D-brane, with Dirichlet boundary conditions in the time direction.

S-duality

Main article: S-duality

Strong–weak duality, a string duality relating theories with a large coupling constant to theories with a small coupling constant

SBB

Standard Big Bang model of the universe

SCFT

Superconformal field theory, a supersymmetric extension of conformal field theory

Schwarz

Named for John Henry Schwarz

Seiberg duality

Main article: Seiberg duality

SGA

Abbreviation for Spectrum-generating algebra

short supermultiplet

A supermultiplet (representation) related to BPS states

sigma model

Main articles: Sigma model and Non-linear sigma model

A classical or quantum model based on the maps from a base manifold to a target manifold.

SL

Special linear group

SLAC

Stanford Linear Accelerator Center

SLC

Stanford Linear Collider

slepton

Main article: slepton

Hypothetical supersymmetric partner of a lepton

SM

Main article: Standard Model

sneutrino

Main article: sneutrino

Hypothetical supersymmetric partner of a neutrino

SO

Special orthogonal group

Sp

Symplectic group

sphaleron

Main article: Sphaleron

Static solution to the electroweak field equations

squark

Main article: squark

Supersymmetric partner of a quark.

SSB

Spontaneous symmetry breaking

SSM

Standard solar model

stress–energy tensor

Alternative name for the #energy–momentum tensor.

string field theory

Main article: string field theory

SU

Special unitary group

SUGRA

Short for supergravity

superconformal algebra

Main articles: Neveu–Schwarz algebra and Ramond algebra

A supersymmetric analogue of the Virasoro algebra of conformal symmetries in 2 dimensions

superfield

Main article: Superfield

A supersymmetric analogue of a quantum or classical field

supergravity

Main article: supergravity

A supersymmetric extension of general relativity

supermultiplet

Main article: Supermultiplet

A representation of a supersymmetry algebra

superpotential

Main article: Superpotential

A function of chiral superfield not depending on their superderivatives or spacetime derivatives, used to form a Lagrangian.

superspace

Main article: superspace

A supersymmetric analogue of spacetime

superstring

Main article: superstring

A supersymmetric analogue of a string

supersymmetry

Main articles: supersymmetry and supersymmetry algebra

A generalization of a Lie superalgebra, where the Lie bracket [a,b] is sometimes given by ab+ba rather than ab–ba.

SUSY

An abbreviation for supersymmetry.

SYM

Supersymmetric Yang–Mills

T

t

1.  A top quark.

2.  A Mandelstam variable.

3.  Time.

T

1.  The energy–momentum tensor.

2.  Time, especially the time symmetry.

3.  The transformation τ → τ+1 of the upper half plane.

4.  A torus.

5.  The string tension.

6.  Temperature.

7.  Tensor (current)

T-duality

Main article: T-duality

A string duality relating theories on a large spacetime to theories on a small spacetime. In particular it exchanges type IIA and IIB superstring theory.

tachyon

Main article: Tachyon

A particle of imaginary mass moving faster than light.

ToE

TOE

Theory of everything

type I

type II

type IIA

type IIB

Main article: Type I string theory

Main article: Type II string theory

A type of superstring or the corresponding low-energy supergravity theory. The Roman numeral I or II refers to the number of d=10 supersymmetries, and types IIA or IIB are distinguished by whether the supersymmetries of left and right movers have opposite or identical chiralities.

U

u

1.  An up quark.

2.  A Mandelstam variable.

U

A unitary group.

U-duality

Main article: U-duality

Short for "unified duality". A string duality relating two different string theories.

UED

Universal extra dimensions

UV

Short for ultra-violet, often referring to short-distance singularities.

V

V

1.  A vertex operator.

2.  Vector (current)

V-A

Vector-Axial vector

vector superfield

A type of superfield related to vector supermultiplets.

VEV

Vacuum expectation value of an operator.

vielbein

A frame

vierbein

A frame in 4 dimensions. Sometimes used for a frame in an arbitrary number of dimension by authors who do not care that "vier" means four in German.

Veneziano amplitude

Main article: Veneziano amplitude

The Euler beta function interpreted as a scattering amplitude.

vertex operator

Main article: vertex operator

Virasoro algebra

Main article: Virasoro algebra

A central extension of the Witt algebra of polynomial vector fields on a circle.

W

w

A complex number

W

A W-boson

W-algebra

Main article: W-algebra

A sort of generalization of the Virasoro algebra

Weyl

1.  Named after Hermann Weyl

2.  A Weyl transformation is a rescaling of the world-sheet metric.

3.  Weyl spinor, an element of a half-spin representation in even spacetime dimensions.

WIMP

Weakly interacting massive particle

wino

Main article: wino (particle)

A hypothetical supersymmetric partner of the W-boson.

Witten

Named for Edward Witten.

WMAP

Wilkinson Microwave Anisotropy Probe

world sheet

The 2-dimensional subset of spacetime swept out by a moving string.

world-volume

The p+1-dimensional spacetime volume swept out by a p-brane, as in world-volume action.

WZNW

WZW

Initials of Wess, Zumino, (Novikov), and Witten, as in the WZW model, a σ-model with a group as the target space.

XYZ

x

A real number

X

Used for coordinates in Minkowski space.

y

A real number

YBE

Yang–Baxter equation

YM

Yang–Mills

z

A complex number

Z

1.  A partition function

2.  The Z boson.

An element of the center of an extended supersymmetry algebra.

ZEUS

Main article: ZEUS (particle detector)

zino

Main article: gaugino

A hypothetical supersymmetric partner of the Z-boson.

zweibein

A frame in 2 dimensions