fields and particles in particle physics
and in the standard model of particle physics:
matter field fermions (spinors, Dirac fields)
flavors of fundamental fermions in the standard model of particle physics: | |||
---|---|---|---|
generation of fermions | 1st generation | 2nd generation | 3d generation |
quarks () | |||
up-type | up quark () | charm quark () | top quark () |
down-type | down quark () | strange quark () | bottom quark () |
leptons | |||
charged | electron | muon | tauon |
neutral | electron neutrino | muon neutrino | tau neutrino |
bound states: | |||
mesons | light mesons: pion () ρ-meson () ω-meson () f1-meson a1-meson | strange-mesons: ϕ-meson (), kaon, K*-meson (, ) eta-meson () charmed heavy mesons: D-meson (, , ) J/ψ-meson () | bottom heavy mesons: B-meson () ϒ-meson () |
baryons | nucleons: proton neutron |
(also: antiparticles)
hadrons (bound states of the above quarks)
minimally extended supersymmetric standard model
bosinos:
dark matter candidates
Exotica
In geometric engineering of quantum field theory in intersecting D-brane models the gauge theory which is thought to appear on coincident D-branes (see at gauge enhancement) may play two different roles:
color – it may be a Yang-Mills theory of an “actual” gauge field (carried by gluons) coupled to color charges (carried by quarks) – like quantum chromodynamics;
flavor – it may be the (“chiral”) gauge theory of a hidden local gauge field (carried by mesons) coupled to flavor charges (carried by baryons) – like quantum hadrodynamics.
In the first case one speaks of color branes, in the second of flavor branes. Typically one indicates the number of coincident such branes with
for the number of color branes, leading (in the absence of orientifolds) to gauge group SU;
for the number of flavor branes, leading to flavor-symmetry group (“chiral symmetry”) SU (e.g. isospin for ).
color charge | flavor charge | |
---|---|---|
gauge bosons | gluons (gauge group-local symmetry) | mesons (flavor-hidden local symmetry) |
fermions | quarks | baryons |
In common constructions of holographic QCD in the large-N limit (large number of color charges) in which the AdS/QCD correspondence applies, color branes are modeled as black branes while flavor branes are modeled as probe branes (Karch-Katz 02).
From Ouyang 03, p. 2:
the important feature seems to be that the added branes must be extended along the radial AdS direction; then, volume factors suppress the dynamics of the NN strings on these “flavor branes”, which then contribute states to the gauge theory with global symmetries rather than gauge symmetries.
For example, in the Witten-Sakai-Sugimoto model for holographic QCD realized on D4-D8 brane intersections, the D4-branes play the role of color branes while the D8-branes play the role of flavor branes.
graphics from Sati-Schreiber 19c
Here we are showing
with
the 5d Chern-Simons theory on their worldvolume
the corresponding 4d WZW model on the boundary
exhibiting the vector meson fields in the Skyrmion model;
(see below at Baryons);
the Yang-Mills monopole D6-branes
(see at D6-D8-brane bound state);
the NS5-branes (often not considered here).
graphics from Sati-Schreiber 19c
The geometric engineering of QFT on flavor branes (as in the Witten-Sakai-Sugimoto model) realizes, at least qualitatively, the following experimentall phenomena:
The concept of flavor branes in the context of holographic QCD properly originates with:
based on the concept of probe branes due to
Other early discussion:
Peter Ouyang, Holomorphic D7-Branes and Flavored Gauge Theories, Nucl. Phys. B699:207-225, 2004 (arXiv:hep-th/0311084)
Thomas S. Levi, Peter Ouyang, Mesons and Flavor on the Conifold, Phys. Rev. D76:105022, 2007 (arXiv:hep-th/0506021)
Carlos Nunez, A. Paredes, A.V. Ramallo, Flavoring the gravity dual of Yang-Mills with probes, JHEP 0312:024, 2003 (arXiv:hep-th/0311201)
See also:
Emergence of SU(2) flavor-symmetry on single M5-branes in heterotic M-theory on ADE-orbifolds (in the D=6 N=(1,0) SCFT on small instantons in heterotic string theory):
Abhijit Gadde, Babak Haghighat, Joonho Kim, Seok Kim, Guglielmo Lockhart, Cumrun Vafa, Section 4.2 of: 6d String Chains, J. High Energ. Phys. 2018, 143 (2018) (arXiv:1504.04614, doi:10.1007/JHEP02(2018)143)
Kantaro Ohmori, Section 2.3.1 of: Six-Dimensional Superconformal Field Theories and Their Torus Compactifications, Springer Theses 2018 (springer:book/9789811330919)
Argument for this by translation under duality between M-theory and type IIA string theory to half NS5-brane/D6/D8-brane bound state systems in type I' string theory:
Reviewed in:
The emergence of flavor in these half NS5-brane/D6/D8-brane bound state systems, due to the semi-infinite extension of the D6-branes making them act as flavor branes:
Amihay Hanany, Alberto Zaffaroni, Branes and Six Dimensional Supersymmetric Theories, Nucl.Phys. B529 (1998) 180-206 (arXiv:hep-th/9712145)
Ilka Brunner, Andreas Karch, Branes at Orbifolds versus Hanany Witten in Six Dimensions, JHEP 9803:003, 1998 (arXiv:hep-th/9712143)
Reviewed in:
See also:
Last revised on June 14, 2024 at 08:22:22. See the history of this page for a list of all contributions to it.