nLab D-term

Contents

Context

Algebraic Quantum Field Theory

algebraic quantum field theory (perturbative, on curved spacetimes, homotopical)

Introduction

Concepts

field theory:

Lagrangian field theory

quantization

quantum mechanical system, quantum probability

free field quantization

gauge theories

interacting field quantization

renormalization

Theorems

States and observables

Operator algebra

Local QFT

Perturbative QFT

Fields and quanta

fields and particles in particle physics

and in the standard model of particle physics:

force field gauge bosons

scalar bosons

matter field fermions (spinors, Dirac fields)

flavors of fundamental fermions in the
standard model of particle physics:
generation of fermions1st generation2nd generation3d generation
quarks (qq)
up-typeup quark (uu)charm quark (cc)top quark (tt)
down-typedown quark (dd)strange quark (ss)bottom quark (bb)
leptons
chargedelectronmuontauon
neutralelectron neutrinomuon neutrinotau neutrino
bound states:
mesonslight mesons:
pion (udu d)
ρ-meson (udu d)
ω-meson (udu d)
f1-meson
a1-meson
strange-mesons:
ϕ-meson (ss¯s \bar s),
kaon, K*-meson (usu s, dsd s)
eta-meson (uu+dd+ssu u + d d + s s)

charmed heavy mesons:
D-meson (uc u c, dcd c, scs c)
J/ψ-meson (cc¯c \bar c)
bottom heavy mesons:
B-meson (qbq b)
ϒ-meson (bb¯b \bar b)
baryonsnucleons:
proton (uud)(u u d)
neutron (udd)(u d d)

(also: antiparticles)

effective particles

hadrons (bound states of the above quarks)

solitons

in grand unified theory

minimally extended supersymmetric standard model

superpartners

bosinos:

sfermions:

dark matter candidates

Exotica

auxiliary fields

Contents

Idea

In quantum hadrodynamics, the D-term is a subtle conserved charge of hadrons (alongside the well-known charges of mass, spin and electric charge), which may be understood as a limit of a gravitational form factor. Accordingly, the most natural way to measure the D-term charge for any particle is (or would be) via scattering with gravitons and, as a result, there is currently no experimental determination of the D-term of any particle.

But more indirect measurements of the D-term may be possible (cf. BEG18), such as at a future electron-ion collider, the vague prospect of which recently led to renewed attention of the problem (see FHSU22, p. 1).

Generally, it is expected that the D-term must be negative for otherwise hadrons would seem to be unstable.

A computation of the D-term via holographic QCD is claimed in FHSU22, whose authors indeed find a (small and) negative value.

References

Original articles:

Review:

Experimental measurement:

  • V. D. Burkert, L. Elouadrhiri, F. X. Girod, The pressure distribution inside the proton, Nature 557 (2018) 396–399 [[doi:10.1038/s41586-018-0060-z]]

Computation/prediction of the D-term for hadrons via holographic QCD, specifically via D4-D8-brane bound states:

Last revised on June 15, 2022 at 05:50:51. See the history of this page for a list of all contributions to it.