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\section*{AdS-QCD correspondence}

\hypertarget{context}{}\subsubsection*{{Context}}\label{context}

\hypertarget{duality_in_string_theory}{}\paragraph*{{Duality in string theory}}\label{duality_in_string_theory}

[[!include duality in string theory -- contents]]

\hypertarget{quantum_field_theory}{}\paragraph*{{Quantum field theory}}\label{quantum_field_theory}

[[!include functorial quantum field theory - contents]]

\hypertarget{contents}{}\section*{{Contents}}\label{contents}

\noindent\hyperlink{idea}{Idea}\dotfill \pageref*{idea} \linebreak
\noindent\hyperlink{Models}{Models}\dotfill \pageref*{Models} \linebreak
\noindent\hyperlink{TopDownModels}{Top-down models}\dotfill \pageref*{TopDownModels} \linebreak
\noindent\hyperlink{WittenSakaiSugimotoModel}{Witten-Sakai-Sugimoto model}\dotfill \pageref*{WittenSakaiSugimotoModel} \linebreak
\noindent\hyperlink{WSSBraneConfiguration}{Brane configuration}\dotfill \pageref*{WSSBraneConfiguration} \linebreak
\noindent\hyperlink{glueballs}{Glueballs}\dotfill \pageref*{glueballs} \linebreak
\noindent\hyperlink{Hadrons}{Hadrons}\dotfill \pageref*{Hadrons} \linebreak
\noindent\hyperlink{WSSTypeModelFor2dQCD}{WSS-type model for 2d QCD}\dotfill \pageref*{WSSTypeModelFor2dQCD} \linebreak
\noindent\hyperlink{Type0StringCorrespondence}{Type0B/$YM_4$-correspondence}\dotfill \pageref*{Type0StringCorrespondence} \linebreak
\noindent\hyperlink{BottomUpModels}{Bottom-up models}\dotfill \pageref*{BottomUpModels} \linebreak
\noindent\hyperlink{embedding_into_a_full_standard_model}{Embedding into a full standard model}\dotfill \pageref*{embedding_into_a_full_standard_model} \linebreak
\noindent\hyperlink{related_concepts}{Related concepts}\dotfill \pageref*{related_concepts} \linebreak
\noindent\hyperlink{references}{References}\dotfill \pageref*{references} \linebreak
\noindent\hyperlink{ReferencesGeneral}{General}\dotfill \pageref*{ReferencesGeneral} \linebreak
\noindent\hyperlink{hadron_physics}{Hadron physics}\dotfill \pageref*{hadron_physics} \linebreak
\noindent\hyperlink{baryons_as_instantons}{Baryons as instantons}\dotfill \pageref*{baryons_as_instantons} \linebreak
\noindent\hyperlink{baryons_as_wrapped_branes}{Baryons as wrapped branes}\dotfill \pageref*{baryons_as_wrapped_branes} \linebreak
\noindent\hyperlink{ReferencesBaryonsSkyrmions}{Baryons as Skyrmions}\dotfill \pageref*{ReferencesBaryonsSkyrmions} \linebreak
\noindent\hyperlink{pentaquarks}{Pentaquarks}\dotfill \pageref*{pentaquarks} \linebreak
\noindent\hyperlink{glueball_physics}{Glueball physics}\dotfill \pageref*{glueball_physics} \linebreak
\noindent\hyperlink{application_to_the_quarkgluon_plasma}{Application to the quark-gluon plasma}\dotfill \pageref*{application_to_the_quarkgluon_plasma} \linebreak
\noindent\hyperlink{application_to_lepton_anomalous_magnetic_moment}{Application to lepton anomalous magnetic moment}\dotfill \pageref*{application_to_lepton_anomalous_magnetic_moment} \linebreak
\noindent\hyperlink{ReferencesApplicationToHiggsField}{Application to Higgs field}\dotfill \pageref*{ReferencesApplicationToHiggsField} \linebreak
\noindent\hyperlink{application_to_angle_axions_and_strong_cpproblem}{Application to $\theta$-angle axions and strong CP-problem}\dotfill \pageref*{application_to_angle_axions_and_strong_cpproblem} \linebreak
\noindent\hyperlink{application_to_the_qcd_trace_anomaly}{Application to the QCD trace anomaly}\dotfill \pageref*{application_to_the_qcd_trace_anomaly} \linebreak
\noindent\hyperlink{application_to_parton_distribution}{Application to parton distribution}\dotfill \pageref*{application_to_parton_distribution} \linebreak
\noindent\hyperlink{ReferencesColourSuperconductivity}{Application to QCD phases}\dotfill \pageref*{ReferencesColourSuperconductivity} \linebreak
\noindent\hyperlink{application_to_defects}{Application to defects}\dotfill \pageref*{application_to_defects} \linebreak


\hypertarget{idea}{}\subsection*{{Idea}}\label{idea}

The [[geometric engineering of QFT|geometric engineering]] of [[quantum chromodynamics]] via [[D4-D8-brane bound state]] [[intersecting D-brane models]] is traditionally referred to as the \emph{AdS/QCD correspondence} or as \emph{holographic QCD}, or similar, referring to the use of the \emph{[[AdS/CFT correspondence]]}. (Notice ``CFT'' as opposed to ``QCD'').

The [[AdS-CFT correspondence]] applies \emph{exactly} only to a few highly symmetric [[quantum field theories]], notably to [[N=4 D=4 super Yang-Mills theory]]. However, away from these special points in field theory space the correspondence does not completely break down, but continues to apply in some approximation and/or with suitable modifications on the [[gravity]]-side of the correspondence.

Notably [[quantum chromodynamics]] (one sector of the [[standard model of particle physics]]) is crucially different from, but still similar enough to, [[N=4 D=4 super Yang-Mills theory]] that some of its [[observables]], in particular otherwise intractable [[non-perturbative effects]], have been argued to be usefully approximated by [[AdS-CFT]]-type [[duality in string theory|dual]] [[supergravity]]-[[observables]].

In particular, the realization of [[quantum chromodynamics]] by [[intersecting D-brane models]] gives a conceptual analytic handle on [[confinement|confined]] [[hadron]] spectra, hence of the physics of ordinary [[atomic nuclei]] (see \hyperlink{Hadrons}{below}). This means (\hyperlink{Witten98}{Witten 98}) that AdS/QCD provides a conceptual solution to the \emph{[[mass gap problem]]} (albeit not yet a rigorous one), which is out of reach for [[perturbative quantum field theory|perturbation theory]] and otherwise computable only via the blind numerics of [[lattice QCD]].

\begin{quote}%
graphics grabbed from \hyperlink{AHI12}{Aoki-Hashimoto-Iizuka 12}


\end{quote}
Another example of such observables is the [[shear viscosity]] of the [[quark-gluon plasma]].

This approach is hence called the \emph{AdS/QCD-correspondence} or \emph{holographic QCD} or similar (see also [[AdS-CFT in condensed matter physics]] for similar relations).

 From \hyperlink{SuganumaNakagawaMatsumoto16}{Suganuma-Nakagawa-Matsumoto 16, p. 1}:

\begin{quote}%
Since 1973, [[quantum chromodynamics]] (QCD) has been established as the fundamental theory of the [[strong nuclear force|strong interaction]]. Nevertheless, it is very difficult to solve QCD directly in an analytical manner, and many effective models of QCD have been used instead of QCD, but most models cannot be derived from QCD and its connection to QCD is unclear.

To analyze nonperturbative QCD, the [[lattice QCD]] Monte Carlo simulation has been also used as a first-principle calculation of the strong interaction. However, it has several weak points. For example, the [[quantum state|state]] information (e.g. the [[wave function]]) is severely limited, because [[lattice QCD]] is based on the [[path-integral]] formalism. Also, it is difficult to take the [[chiral fermion|chiral]] limit, because zero-mass [[pions]] require [[large volume limit|infinite volume lattices]]. There appears a notorious ``\href{lattice+gauge+theory#SignProblem}{sign problem}'' at finite density.

On the other hand, [[holographic QCD]] has a direct connection to [[QCD]], and can be derived from QCD in some limit. In fact, [[holographic QCD]] is equivalent to infrared QCD in [[large N limit|large Nc]] and strong [[`t Hooft coupling]] $\lambda$, via gauge/gravity correspondence. Remarkably, holographic QCD is successful to reproduce many hadron phenomenology such as vector meson dominance, the KSRF relation, hidden local symmetry, the GSW model and the Skyrme soliton picture. Unlike lattice QCD simulations, holographic QCD is usually formulated in the chiral limit, and does not have the \href{lattice+gauge+theory#SignProblem}{sign problem} at finite density.


\end{quote}
\hypertarget{Models}{}\subsection*{{Models}}\label{Models}

In approaches to $AdS/QCD$ one distinguishes [[top-down model building]] -- where the ambition is to first set up a globally consistent ambient [[intersecting D-brane model]] where a [[Yang-Mills theory]] at least similar to [[QCD]] arises on suitable [[D-branes]] ([[geometric engineering of gauge theories]]) -- from [[bottom-up model building]] approaches which are more cavalier about global consistency and first focus on accurately fitting the intended [[phenomenology]] of [[QCD]] as the [[asymptotic boundary|asymptotic]] [[boundary field theory]] of [[gravity]]+[[gauge theory]] on some [[anti de Sitter spacetime]]. (Eventually both these approaches should meet ``in the middle'' to produce a [[model (in theoretical physics)|model]] which is both [[standard model of particle physics|realistic]] as well as globally consistent as a [[string vacuum]]; see also at \emph{[[string phenomenology]]}.)

\begin{quote}%
graphics grabbed from \href{bottom-up+and+top-down+model+building#AldazabalIbanezQuevedoUranga00}{Aldazabal-Ibáñez-Quevedo-Uranga 00}


\end{quote}
\hypertarget{TopDownModels}{}\subsubsection*{{Top-down models}}\label{TopDownModels}

\hypertarget{WittenSakaiSugimotoModel}{}\paragraph*{{Witten-Sakai-Sugimoto model}}\label{WittenSakaiSugimotoModel}

A good [[top-down model building]]-approach to AdS/QCD is due to \hyperlink{SakaiSugimoto04}{Sakai-Sugimoto 04}, \hyperlink{SakaiSugimoto05}{Sakai-Sugimoto 05} based on \hyperlink{Witten98}{Witten 98}, see \hyperlink{Rebhan14}{Rebhan 14}, \hyperlink{Sugimoto16}{Sugimoto 16} for review.

\hypertarget{WSSBraneConfiguration}{}\paragraph*{{Brane configuration}}\label{WSSBraneConfiguration}

This model realizes something close to [[QCD]] on [[intersecting D-brane models|coincident]] [[black brane|black]] [[M5-branes]] with [[near horizon geometry]] a [[KK-compactification]] of $AdS_7 \times S^4$ in the decoupling limit where the [[worldvolume]] theory becomes the [[6d (2,0)-superconformal SCFT]]. The [[KK-compactification]] is on a [[torus]] with anti-periodic boundary conditions for the [[fermions]] in one direction, thus [[spontaneous symmetry breaking|breaking]] all [[supersymmetry]] ([[Scherk-Schwarz mechanism]]). Here the first circle [[KK-compactification|reduction]] realizes, under [[duality between M-theory and type IIA string theory]], the [[M5-branes]] as [[D4-branes]], hence the model now looks like 5d [[Yang-Mills theory]] further [[KK-compactification|compactified]] on a circle. (\hyperlink{Witten98}{Witten 98, section 4}).

The further introduction of [[intersecting D-brane model|intersecting]] [[D8-branes]] and [[anti D-brane|anti]] [[D8-branes]] to [[D4-D8 brane bound states]] makes a sensible sector of [[chiral fermions]] appear in this model (\hyperlink{SakaiSugimoto04}{Sakai-Sugimoto 04}, \hyperlink{SakaiSugimoto05}{Sakai-Sugimoto 05})

The following diagram indicates the Witten-Sakai-Sugimoto [[intersecting D-brane model]] that [[geometric engineering of QFT|geometrically engineers]] [[QCD]]:

Here are some further illustrations, taken from the literature:

\begin{quote}%
graphics grabbed from \hyperlink{Erlich09}{Erlich 09, section 1.1}


\end{quote}
\begin{quote}%
graphics grabbed from \hyperlink{Rebhan14}{Rebhan 14}


\end{quote}
\hypertarget{glueballs}{}\paragraph*{{Glueballs}}\label{glueballs}

Already before adding the D8-branes (hence already in the Witten model) this produces a pure [[Yang-Mills theory]] whose [[glueball]]-spectra may usefully be compared to those of [[QCD]]:

\begin{quote}%
graphics grabbed from \hyperlink{Rebhan14}{Rebhan 14}


\end{quote}
\hypertarget{Hadrons}{}\paragraph*{{Hadrons}}\label{Hadrons}

In this [[Witten-Sakai-Sugimoto model]] for [[non-perturbative effect|strongly coupled]] [[QCD]] the [[hadrons]] in [[QCD]] correspond to [[string theory|string-theoretic]]-phenomena in the [[bulk field theory]]:

\begin{enumerate}%
\item the [[mesons]] ([[bound states]] of 2 [[quarks]]) correspond to [[open strings]] in the bulk, whose two endpoints on the [[asymptotic boundary]] correspond to the two quarks


\item [[baryons]] ([[bound states]] of $N_c$ [[quarks]]) appear in two different but equivalent (\hyperlink{Sugimoto16}{Sugimoto 16, 15.4.1}) guises:

\begin{enumerate}%
\item as [[wrapped brane|wrapped]] [[D4-branes]] with $N_c$ [[open strings]] connecting them to the [[D8-brane]]

(\hyperlink{Witten98b}{Witten 98b}, \hyperlink{GrossOoguri98}{Gross-Ooguri 98, Sec. 5}, \hyperlink{BISY98}{BISY 98}, \hyperlink{CGS98}{CGS98})


\item as [[skyrmions]]

(\hyperlink{SakaiSugimoto04}{Sakai-Sugimoto 04, section 5.2}, \hyperlink{SakaiSugimoto05}{Sakai-Sugimoto 05, section 3.3}, see \hyperlink{Bartolini17}{Bartolini 17}).



\end{enumerate}


\end{enumerate}
For review see \hyperlink{Sugimoto16}{Sugimoto 16}, also \hyperlink{Rebhan14}{Rebhan 14, around (18)}.

\begin{quote}%
graphics grabbed from \hyperlink{Sugimoto16}{Sugimoto 16}


\end{quote}
Equivalently, these baryon states are the [[Yang-Mills instantons]] on the [[D8-brane]] giving the [[D4-D8 brane bound state]] (\hyperlink{SakaiSugimoto04}{Sakai-Sugimoto 04, 5.7}) as a special case of the general situation for [[Dp-D(p+4)-brane bound states]] (e.g. \href{Dp-D%28p%2B4%29-brane+bound+state#Tong05}{Tong 05, 1.4}).

\begin{quote}%
graphics grabbed from \hyperlink{CaiLi17}{Cai-Li 17}


\end{quote}
\begin{quote}%
graphics grabbed from \hyperlink{ABBCN18}{ABBCN 18}


\end{quote}
This already produces [[baryon]] [[mass]] spectra with moderate quantitative agreement with [[experiment]] (\hyperlink{HSSY07}{HSSY 07}):

\begin{quote}%
graphics grabbed from \hyperlink{Sugimoto16}{Sugimoto 16}


\end{quote}
Moreover, the above 4-brane model for baryons is claimed to be equivalent to the old \textbf{[[Skyrmion]] model} (see \hyperlink{SakaiSugimoto04}{Sakai-Sugimoto 04, section 5.2}, \hyperlink{SakaiSugimoto05}{Sakai-Sugimoto 05, section 3.3}, \hyperlink{Sugimoto16}{Sugimoto 16, 15.4.1}, \hyperlink{Bartolini17}{Bartolini 17}).

But the Skyrmion model of baryons has been shown to apply also to [[bound states]] of [[baryons]], namely the [[atomic nuclei]] (\href{Skyrmion#Riska93}{Riska 93}, \href{Skyrmion#BattyeMantonSutcliffe10}{Battye-Manton-Sutcliffe 10}, \href{Skyrmion#Manton16}{Manton 16}, \href{Skyrmion#NayaSutcliffe18}{Naya-Sutcliffe 18}), at least for small [[atomic number]].

For instance, various [[experiment|experimentally]] observed resonances of the [[carbon]] [[nucleus]] are modeled well by a Skyrmion with [[atomic number]] 6 and hence baryon number 12 (\href{Skyrmion#LauMaonton14}{Lau-Manton 14}):

$\backslash$begin\{center\}  $\backslash$end\{center\}

\begin{quote}%
graphics grabbed form \href{Skyrmion#LauMaonton14}{Lau-Manton 14}


\end{quote}
More generally, the [[Skyrmion]]-model of [[atomic nuclei]] gives good matches with [[experiment]] if not just the [[pi meson]] but also the [[rho meson]]-background is included (\href{Skyrmion#NayaSutcliffe18}{Naya-Sutcliffe 18}):

$\backslash$begin\{center\}  $\backslash$end\{center\}

\begin{quote}%
graphics grabbed form \href{Skyrmion#NayaSutcliffe18}{Naya-Sutcliffe 18}


\end{quote}


\hypertarget{WSSTypeModelFor2dQCD}{}\paragraph*{{WSS-type model for 2d QCD}}\label{WSSTypeModelFor2dQCD}

There is a direct analogue for [[2d QCD]] of the \hyperlink{WittenSakaiSugimotoModel}{above} [[WSS model]] for 4d [[QCD]] (\hyperlink{GaoXuZeng06}{Gao-Xu-Zeng 06}, \hyperlink{YeeZahed11}{Yee-Zahed 11}).

The corresponding [[intersecting D-brane model]] is much as that for 4d QCD \hyperlink{WSSBraneConfiguration}{above}, just with

\begin{enumerate}%
\item [[colour charge|color]] [[D2-branes]] instead of [[D4-branes]];


\item [[baryon]]$\,$ [[D6-branes]] instead of [[D4-branes]];


\item [[meson]]$\,$ [[field (physics)|fields]] given by 3d [[Chern-Simons theory]] instead of [[5d Chern-Simons theory]]:



\end{enumerate}
\hypertarget{Type0StringCorrespondence}{}\paragraph*{{Type0B/$YM_4$-correspondence}}\label{Type0StringCorrespondence}

Instead of starting with [[M5-branes]] in [[supergravity|locally supersymmetric]] [[M-theory]] and then [[spontaneously broken symmetry|spontaneously breaking]] all [[supersymmetry]] by suitable [[KK-compactification]] as in the \hyperlink{WittenSakaiSugimotoModel}{Witten-Sakai-Sugimoto model}, one may start with a non-supersymmetric [[bulk field theory|bulk]] [[string theory]] in the first place.

In this vein, it has been argued in \hyperlink{GLMR00}{GLMR 00} that there is holographic duality between [[type 0 string theory]] and non-supersymmetric 4d [[Yang-Mills theory]] (hence potentially something close to [[QCD]]). See also \hyperlink{AAS19}{AAS 19}.

\hypertarget{BottomUpModels}{}\subsubsection*{{Bottom-up models}}\label{BottomUpModels}

A popular [[bottom-up model building|bottom-up approach]] of AdS/QCD is known as the \emph{hard-wall model} (\hyperlink{ErlichKatzSonStephanov05}{Erlich-Katz-Son-Stephanov 05}).

Computations due to \hyperlink{KatzLewandowskiSchwartz05}{Katz-Lewandowski-Schwartz 05} find the following comparison of AdS/QCD predictions to [[QCD]]-[[experiment]]

\begin{quote}%
graphics grabbed from \hyperlink{Erlich09}{Erlich 09, section 1.2}


\end{quote}
Further refinement to the ``soft-wall model'' is due to \hyperlink{KKSS06}{KKSS 06} and further to ``improved holographic QCD'' is due to \hyperlink{GursoyKiritsisNitti07}{Gursoy-Kiritsis-Nitti 07}, \hyperlink{GursoyKiritsis08}{Gursoy-Kiritsis 08}, see \hyperlink{GKMMN10}{GKMMN 10}.

\begin{quote}%
graphics grabbed from \hyperlink{GKMMN10}{GKMMN 10}


\end{quote}
\begin{quote}%
graphics grabbed from \hyperlink{GKMMN10}{GKMMN 10}


\end{quote}
These computations shown so far all use just the field theory in the bulk, not yet the stringy modes ([[limit of a sequence|limit]] of vanishing [[string length]] $\sqrt{\alpha'} \to 0$). Incorporating bulk string corrections further improves these results, see \hyperlink{SonnenscheinWeissman18}{Sonnenschein-Weissman 18}.

\hypertarget{embedding_into_a_full_standard_model}{}\subsubsection*{{Embedding into a full standard model}}\label{embedding_into_a_full_standard_model}

\hyperlink{Nastase03}{Nastase 03, p. 2}:

\begin{quote}%
An obvious question then is can one lift this D brane construction for the holographic dual of [[QCD]] to a [[standard model of particle physics|Standard Model]] embedding? I study this question in the context of [[intersecting D-brane models|D-brane-world]] [[GUT]] models and find that one needs to have [[TeV-scale string theory]].


\end{quote}
\hypertarget{related_concepts}{}\subsection*{{Related concepts}}\label{related_concepts}

\begin{itemize}%
\item [[holographic entanglement entropy]]


\item [[AdS-CFT in condensed matter physics]]


\item [[lattice QCD]]



\end{itemize}
\hypertarget{references}{}\subsection*{{References}}\label{references}

\hypertarget{ReferencesGeneral}{}\subsubsection*{{General}}\label{ReferencesGeneral}

Review:

\begin{itemize}%
\item [[Ofer Aharony]], \emph{The non-AdS/non-CFT correspondence, or three different paths to QCD}, Progress in string, field and particle theory. Springer, Dordrecht, 2003. 3-24 (\href{https://arxiv.org/abs/hep-th/0212193}{arXiv:hep-th/0212193})


\item Joshua Erlich, \emph{How Well Does AdS/QCD Describe QCD?}, Int. J. Mod. Phys.A25:411-421,2010 (\href{https://arxiv.org/abs/0908.0312}{arXiv:0908.0312})


\item Marco Panero, \emph{QCD thermodynamics in the large-$N$ limit}, 2010 ([[PaneroAdsQCD.pdf:file|pdf]])


\item Youngman Kim and Deokhyun Yi, \emph{Holography at Work for Nuclear and Hadron Physics}, Advances in High Energy Physics, Volume 2011, Article ID 259025, 62 pages (\href{https://arxiv.org/abs/1107.0155}{arXiv:1107.0155}, \href{http://dx.doi.org/10.1155/2011/259025}{doi:10.1155/2011/259025})


\item M. R. Pahlavani, R. Morad, \emph{Application of AdS/CFT in Nuclear Physics}, Advances in High Energy Physics (\href{https://arxiv.org/abs/1403.2501}{arXiv:1403.2501})


\item Jorge Casalderrey-Solana, Hong Liu, David Mateos, Krishna Rajagopal, Urs Achim Wiedemann,

\emph{Gauge/string duality, hot QCD and heavy ion collisions},

Cambridge University Press, 2014 (\href{https://arxiv.org/abs/1101.0618}{arXiv:1101.0618}) -7+9 32


\item Sinya Aoki, [[Koji Hashimoto]], Norihiro Iizuka, \emph{Matrix Theory for Baryons: An Overview of Holographic QCD for Nuclear Physics}, Reports on Progress in Physics, Volume 76, Number 10 (\href{https://arxiv.org/abs/1203.5386}{arxiv:1203.5386})


\item Youngman Kim, Ik Jae Shin, Takuya Tsukioka, \emph{Holographic QCD: Past, Present, and Future}, Progress in Particle and Nuclear Physics Volume 68, January 2013, Pages 55-112 Progress in Particle and Nuclear Physics (\href{https://arxiv.org/abs/1205.4852}{arXiv:1205.4852})


\item Joshua Erlich, \emph{An Introduction to Holographic QCD for Nonspecialists}, Contemporary Physics (\href{https://arxiv.org/abs/1407.5002}{arXiv:1407.5002})


\item Alberto Guijosa, \emph{QCD, with Strings Attached}, IJMPE Vol. 25, No. 10 (2016) 1630006 (\href{https://arxiv.org/abs/1611.07472}{arXiv:1611.07472})



\end{itemize}
See also

\begin{itemize}%
\item Wikipedia, \emph{\href{https://en.wikipedia.org/wiki/AdS/QCD_correspondence}{AdS/QCD correspondence}}

\end{itemize}
The top-down Sakai-Sugimoto model is due to

\begin{itemize}%
\item [[Tadakatsu Sakai]], [[Shigeki Sugimoto]], \emph{Low energy hadron physics in holographic QCD}, Prog.Theor.Phys.113:843-882, 2005 (\href{https://arxiv.org/abs/hep-th/0412141}{arXiv:hep-th/0412141})


\item [[Tadakatsu Sakai]], [[Shigeki Sugimoto]], \emph{More on a holographic dual of QCD}, Prog.Theor.Phys.114:1083-1118, 2005 (\href{https://arxiv.org/abs/hep-th/0507073}{arXiv:hep-th/0507073})



\end{itemize}
along the lines of

\begin{itemize}%
\item [[Andreas Karch]], [[Emanuel Katz]], \emph{Adding flavor to AdS/CFT}, JHEP 0206:043, 2002 (\href{https://arxiv.org/abs/hep-th/0205236}{arxiv:hep-th/0205236})

\end{itemize}
and based on

\begin{itemize}%
\item [[Edward Witten]], \emph{Anti-de Sitter Space, Thermal Phase Transition, And Confinement In Gauge Theories}, Adv. Theor. Math. Phys.2:505-532, 1998 (\href{https://arxiv.org/abs/hep-th/9803131}{arXiv:hep-th/9803131})

\end{itemize}
further developed in

\begin{itemize}%
\item Lorenzo Bartolini, Stefano Bolognesi, Andrea Proto, \emph{From the Sakai-Sugimoto Model to the Generalized Skyrme Model}, Phys. Rev. D 97, 014024 2018 (\href{https://arxiv.org/abs/1711.03873}{arXiv:1711.03873})

\end{itemize}
reviewed in

\begin{itemize}%
\item Anton Rebhan, \emph{The Witten-Sakai-Sugimoto model: A brief review and some recent results}, 3rd International Conference on New Frontiers in Physics, Kolymbari, Crete, 2014 (\href{https://arxiv.org/abs/1410.8858}{arXiv:1410.8858})

\end{itemize}
More on [[D4-D8 brane bound states]]:

\begin{itemize}%
\item [[Horatiu Nastase]], Sections 2, 3 of: \emph{On Dp-Dp+4 systems, QCD dual and phenomenology} (\href{https://arxiv.org/abs/hep-th/0305069}{arXiv:hep-th/0305069})

\end{itemize}
The Witten-Sakai-Sugimoto model with [[orthogonal group|orthogonal]] [[gauge groups]] realized by [[D4-D8 brane bound states]] at [[O-planes]]:

\begin{itemize}%
\item Toshiya Imoto, [[Tadakatsu Sakai]], [[Shigeki Sugimoto]], \emph{$O(N)$ and $USp(N)$ QCD from String Theory}, Prog.Theor.Phys.122:1433-1453, 2010 (\href{https://arxiv.org/abs/0907.2968}{arXiv:0907.2968})


\item Hee-Cheol Kim, Sung-Soo Kim, Kimyeong Lee, \emph{5-dim Superconformal Index with Enhanced $E_n$ Global Symmetry}, JHEP 1210 (2012) 142 (\href{https://arxiv.org/abs/1206.6781}{arXiv:1206.6781})



\end{itemize}
The analogoue of the WSS model for [[2d QCD]]:

\begin{itemize}%
\item Yi-hong Gao, Weishui Xu, Ding-fang Zeng, \emph{NGN, $QCD_2$ and chiral phase transition from string theory}, Nucl.Phys. B400:181-210, 1993 (\href{https://arxiv.org/abs/hep-th/0605138}{arXiv:hep-th/0605138})

\end{itemize}
Specifically concerning the 3d [[Chern-Simons theory]] on the [[D8-branes]]:

\begin{itemize}%
\item Ho-Ung Yee, Ismail Zahed, \emph{Holographic two dimensional QCD and Chern-Simons term}, JHEP 1107:033, 2011 (\href{https://arxiv.org/abs/1103.6286}{arXiv:1103.6286})

\end{itemize}
and its relation to [[baryons]]:

\begin{itemize}%
\item Hideo Suganuma, Yuya Nakagawa, Kohei Matsumoto, \emph{1+1 Large $N_c$ QCD and its Holographic Dual $\sim$ Soliton Picture of Baryons in Single-Flavor World}, JPS Conf. Proc. 13, 020013 (2017) (\href{https://arxiv.org/abs/1610.02074}{arXiv:1610.02074})

\end{itemize}
The bottom-up hard-wall model is due to

\begin{itemize}%
\item Joshua Erlich, [[Emanuel Katz]], Dam T. Son, Mikhail A. Stephanov, \emph{QCD and a Holographic Model of Hadrons}, Phys.Rev.Lett.95:261602, 2005 (\href{https://arxiv.org/abs/hep-ph/0501128}{arXiv:hep-ph/0501128})

\end{itemize}
while the soft-wall refinement is due to

\begin{itemize}%
\item [[Andreas Karch]], [[Emanuel Katz]], Dam T. Son, Mikhail A. Stephanov, \emph{Linear Confinement and AdS/QCD}, Phys.Rev.D74:015005, 2006 (\href{https://arxiv.org/abs/hep-ph/0602229}{arXiv:hep-ph/0602229})

\end{itemize}
see also

\begin{itemize}%
\item Alfredo Vega, Paulina Cabrera, \emph{Family of dilatons and metrics for AdS/QCD models}, Phys. Rev. D 93, 114026 (2016) (\href{https://arxiv.org/abs/1601.05999}{arXiv:1601.05999})

\end{itemize}
and the version \emph{improved holographic QCD} is due to

\begin{itemize}%
\item Umut Gursoy, [[Elias Kiritsis]], \emph{Exploring improved holographic theories for QCD: Part I}, JHEP 0802:032, 2008 (\href{https://arxiv.org/abs/0707.1324}{arXiv:0707.1324})


\item Umut Gursoy, [[Elias Kiritsis]], Francesco Nitti, \emph{Exploring improved holographic theories for QCD: Part II}, JHEP 0802:019, 2008 (\href{https://arxiv.org/abs/0707.1349}{arXiv:0707.1349})



\end{itemize}
reviewed in

\begin{itemize}%
\item Umut Gürsoy, [[Elias Kiritsis]], Liuba Mazzanti, Georgios Michalogiorgakis, Francesco Nitti, \emph{Improved Holographic QCD}, Lect.Notes Phys.828:79-146,2011 (\href{https://arxiv.org/abs/1006.5461}{arXiv:1006.5461})

\end{itemize}
More developments on improved holographic QCD:

\begin{itemize}%
\item Takaaki Ishii, Matti Järvinen, Govert Nijs, \emph{Cool baryon and quark matter in holographic QCD} (\href{https://arxiv.org/abs/1903.06169}{arXiv:1903.06169})

\end{itemize}
The extreme form of bottom-up holographic model building is explored in

\begin{itemize}%
\item [[Koji Hashimoto]], Sotaro Sugishita, Akinori Tanaka, Akio Tomiya, \emph{Deep Learning and Holographic QCD}, Phys. Rev. D 98, 106014 (2018) (\href{https://arxiv.org/abs/1809.10536}{arXiv:1809.10536})

\end{itemize}
where an appropriate [[bulk]] geometry is computer-generated from specified boundary behaviour.

The light-front holography approach is reviewed in

\begin{itemize}%
\item Liping Zou, H.G. Dosch, \emph{A very Practical Guide to Light Front Holographic QCD}, (\href{https://arxiv.org/abs/1801.00607}{arXiv:1801.00607})

\end{itemize}
see also

\begin{itemize}%
\item Harun Omer, \emph{Embedding LFHQCD in Worldsheet String Theory} (\href{https://arxiv.org/abs/1909.12866}{arXiv:1909.12866})

\end{itemize}
\hypertarget{hadron_physics}{}\subsubsection*{{Hadron physics}}\label{hadron_physics}

Application to [[confinement|confined]] [[hadron]]-physics:

Review:

\begin{itemize}%
\item Henrique Boschi-Filho, \emph{Hadrons in AdS/QCD models}, Journal of Physics: Conference Series, Volume 706, Section 4 2008 (\href{http://iopscience.iop.org/article/10.1088/1742-6596/706/4/042008}{doi:10.1088/1742-6596/706/4/042008})


\item Kanabu Nawa, Hideo Suganuma, Toru Kojo, \emph{Baryons in Holographic QCD}, Phys.Rev.D75:086003, 2007 (\href{https://arxiv.org/abs/hep-th/0612187}{arXiv:hep-th/0612187})


\item Deog Ki Hong, Mannque Rho, Ho-Ung Yee, Piljin Yi, \emph{Chiral Dynamics of Baryons from String Theory}, Phys.Rev.D76:061901, 2007 (\href{https://arxiv.org/abs/hep-th/0701276}{arXiv:hep-th/0701276})


\item Deog Ki Hong, \emph{Baryons in holographic QCD}, talk at \emph{\href{http://www.int.washington.edu/PROGRAMS/08-1.html}{From Strings to Things 2008}} (\href{http://www.int.washington.edu/talks/WorkShops/int_08_1/People/Hong_D/Hong.pdf}{pdf})


\item Johanna Erdmenger, Nick Evans, Ingo Kirsch, Ed Threlfall, \emph{Mesons in Gauge/Gravity Duals - A Review}, Eur. Phys. J. A35:81-133, 2008 (\href{https://arxiv.org/abs/0711.4467}{arXiv:0711.4467})


\item Stanley J. Brodsky, \emph{Hadron Spectroscopy and Dynamics from Light-Front Holography and Superconformal Algebra} (\href{https://arxiv.org/abs/1802.08552}{arXiv:1802.08552})


\item [[Koji Hashimoto]], [[Tadakatsu Sakai]], [[Shigeki Sugimoto]], \emph{Holographic Baryons : Static Properties and Form Factors from Gauge/String Duality}, Prog. Theor. Phys.120:1093-1137, 2008 (\href{https://arxiv.org/abs/0806.3122}{arXiv:0806.3122})


\item Alex Pomarol, Andrea Wulzer, \emph{Baryon Physics in Holographic QCD}, Nucl. Phys. B809:347-361, 2009 (\href{https://arxiv.org/abs/0807.0316}{arXiv:0807.0316})


\item Thomas Gutsche, Valery E. Lyubovitskij, Ivan Schmidt, Alfredo Vega, \emph{Nuclear physics in soft-wall AdS/QCD: Deuteron electromagnetic form factors}, Phys. Rev. D 91, 114001 (2015) (\href{https://arxiv.org/abs/1501.02738}{arXiv:1501.02738})


\item Marco Claudio Traini, \emph{Generalized Parton Distributions: confining potential effects within AdS/QCD}, Eur. Phys. J. C (2017) 77:246 (\href{https://arxiv.org/abs/1608.08410}{arXiv:1608.08410})


\item Wenhe Cai, Si-wen Li, \emph{Holographic three flavor baryon in the Witten-Sakai-Sugimoto model with the D0-D4 background}, Eur. Phys. J. C (2018) 78: 446 (\href{https://arxiv.org/abs/1712.06304}{arXiv:1712.06304})



\end{itemize}
\hypertarget{baryons_as_instantons}{}\paragraph*{{Baryons as instantons}}\label{baryons_as_instantons}

[[baryons]] as [[instantons]]:

\begin{itemize}%
\item Emanuel Katz, Adam Lewandowski, Matthew D. Schwartz, Phys. Rev. D74:086004, 2006 (\href{https://arxiv.org/abs/hep-ph/0510388}{arXiv:hep-ph/0510388})


\item Hiroyuki Hata, [[Tadakatsu Sakai]], [[Shigeki Sugimoto]], Shinichiro Yamato, \emph{Baryons from instantons in holographic QCD}, Prog.Theor.Phys.117:1157, 2007 (\href{https://arxiv.org/abs/hep-th/0701280}{arXiv:hep-th/0701280})


\item Hiroyuki Hata, Masaki Murata, \emph{Baryons and the Chern-Simons term in holographic QCD with three flavors} (\href{https://arxiv.org/abs/0710.2579}{arXiv:0710.2579})


\item Salvatore Baldino, Stefano Bolognesi, Sven Bjarke Gudnason, Deniz Koksal, \emph{A Solitonic Approach to Holographic Nuclear Physics}, Phys. Rev. D 96, 034008 (2017) (\href{https://arxiv.org/abs/1703.08695}{arXiv:1703.08695})


\item Chandan Mondal, Dipankar Chakrabarti, Xingbo Zhao, \emph{Deuteron transverse densities in holographic QCD}, Eur. Phys. J. A 53, 106 (2017) (\href{https://arxiv.org/abs/1705.05808}{arXiv:1705.05808})


\item Stanley J. Brodsky, \emph{Color Confinement, Hadron Dynamics, and Hadron Spectroscopy from Light-Front Holography and Superconformal Algebra} (\href{https://arxiv.org/abs/1709.01191}{arXiv:1709.01191})


\item Alfredo Vega, M. A. Martin Contreras, \emph{Melting of scalar hadrons in an AdS/QCD model modified by a thermal dilaton} (\href{https://arxiv.org/abs/1808.09096}{arXiv:1808.09096})


\item Meng Lv, Danning Li, Song He, \emph{Pion condensation in a soft-wall AdS/QCD model} (\href{https://arxiv.org/abs/1811.03828}{arXiv:1811.03828})


\item Kazem Bitaghsir Fadafan, Farideh Kazemian, Andreas Schmitt, \emph{Towards a holographic quark-hadron continuity} (\href{https://arxiv.org/abs/1811.08698}{arXiv:1811.08698})


\item Jacob Sonnenschein, Dorin Weissman, \emph{Excited mesons, baryons, glueballs and tetraquarks: Predictions of the Holography Inspired Stringy Hadron model}, (\href{https://arxiv.org/abs/1812.01619}{arXiv:1812.01619})


\item Kazem Bitaghsir Fadafan, Farideh Kazemian, Andreas Schmitt, \emph{Towards a holographic quark-hadron continuity} (\href{https://arxiv.org/abs/1811.08698}{arXiv:1811.08698})


\item M. Abdolmaleki, G.R. Boroun, \emph{The Survey of Proton Structure Function with the AdS/QCD Correspondence} Phys.Part.Nucl.Lett. 15 (2018) no.6, 581-584 (\href{https://doi.org/10.1134/S154747711806002X}{doi:10.1134/S154747711806002X})



\end{itemize}
On relation to [[type 0 string theory]]:

\begin{itemize}%
\item Roberto Grena, Simone Lelli, Michele Maggiore, Anna Rissone, \emph{Confinement, asymptotic freedom and renormalons in type 0 string duals}, JHEP 0007 (2000) 005 (\href{https://arxiv.org/abs/hep-th/0005213}{arXiv:hep-th/0005213})


\item Mohammad Akhond, Adi Armoni, Stefano Speziali, \emph{Phases of $U(N_c)$ $QCD_3$ from Type 0 Strings and Seiberg Duality} (\href{https://arxiv.org/abs/1908.04324}{arxiv:1908.04324})



\end{itemize}
See also

\begin{itemize}%
\item S. S. Afonin, \emph{AdS/QCD without Kaluza-Klein modes: Radial spectrum from higher dimensional QCD operators} (\href{https://arxiv.org/abs/1905.13086}{arXiv:1905.13086})

\end{itemize}
\hypertarget{baryons_as_wrapped_branes}{}\paragraph*{{Baryons as wrapped branes}}\label{baryons_as_wrapped_branes}

[[baryons]] as [[wrapped brane|wrapped]] [[D4-branes]]:

original articles:

\begin{itemize}%
\item [[Edward Witten]], \emph{Baryons And Branes In Anti de Sitter Space}, JHEP 9807:006, 1998 (\href{https://arxiv.org/abs/hep-th/9805112}{arXiv:hep-th/9805112})


\item [[David Gross]], [[Hirosi Ooguri]], \emph{Aspects of Large N Gauge Theory Dynamics as Seen by String Theory}, Phys. Rev. D58:106002,1998 (\href{https://arxiv.org/abs/hep-th/9805129}{arXiv:hep-th/9805129})


\item A. Brandhuber, N. Itzhaki, J. Sonnenschein, S. Yankielowicz \emph{Baryons from Supergravity}, JHEP 9807:020,1998 (\href{https://arxiv.org/abs/hep-th/9806158}{arxiv:hep-th/9806158})


\item Yosuke Imamura, \emph{Supersymmetries and BPS Configurations on Anti-de Sitter Space}, Nucl. Phys. B537:184-202,1999 (\href{https://arxiv.org/abs/hep-th/9807179}{arxiv:hep-th/9807179})


\item Curtis G. Callan, Alberto Guijosa, Konstantin G. Savvidy, \emph{Baryons and String Creation from the Fivebrane Worldvolume Action} (\href{https://arxiv.org/abs/hep-th/9810092}{arxiv:hep-th/9810092})


\item Curtis G. Callan, Alberto Guijosa, Konstantin G. Savvidy, Oyvind Tafjord, \emph{Baryons and Flux Tubes in Confining Gauge Theories from Brane Actions}, Nucl. Phys. B555 (1999) 183-200 (\href{https://arxiv.org/abs/hep-th/9902197}{arxiv:hep-th/9902197})



\end{itemize}
Review:

\begin{itemize}%
\item P. Yi, \emph{Two Approaches to Holographic Baryons/Nuclei}, Few-Body Syst (2013) 54: 77. (\href{https://doi.org/10.1007/s00601-012-0373-7}{doi:10.1007/s00601-012-0373-7})

\end{itemize}
\hypertarget{ReferencesBaryonsSkyrmions}{}\paragraph*{{Baryons as Skyrmions}}\label{ReferencesBaryonsSkyrmions}

[[baryons]] as [[Skyrmions]]:

Review:

\begin{itemize}%
\item [[Shigeki Sugimoto]], \emph{Skyrmion and String theory}, chapter 15 in M. Rho, Ismail Zahed (eds.) \emph{The Multifaceted Skyrmion}, World Scientific 2016 (\href{https://doi.org/10.1142/9710}{doi:10.1142/9710})

\end{itemize}
Original articles

\begin{itemize}%
\item Kanabu Nawa, Hideo Suganuma, Toru Kojo, \emph{Brane-induced Skyrmions: Baryons in Holographic QCD}, Prog.Theor.Phys.Suppl.168:231-236, 2007 (\href{https://arxiv.org/abs/hep-th/0701007}{arXiv:hep-th/0701007})


\item Hovhannes R. Grigoryan, \emph{Baryon as skyrmion-like soliton from the holographic dual model of QCD}, talk at \emph{\href{http://www.int.washington.edu/PROGRAMS/08-1.html}{From Strings to Things 2008}} (\href{https://www.jlab.org/div_dept/theory/talks/2008/grigoryan08_INT.pdf}{pdf})


\item Paul Sutcliffe, \emph{Skyrmions, instantons and holography}, JHEP 1008:019, 2010 (\href{https://arxiv.org/abs/1003.0023}{arXiv:1003.0023})


\item Paul Sutcliffe, \emph{Holographic Skyrmions}, Mod.Phys.Lett. B29 (2015) no.16, 1540051 (\href{http://inspirehep.net/record/1383608}{spire:1383608})


\item Stefano Bolognesi, Paul Sutcliffe, \emph{The Sakai-Sugimoto soliton}, JHEP 1401:078, 2014 (\href{https://arxiv.org/abs/1309.1396}{arXiv:1309.1396})



\end{itemize}
\hypertarget{pentaquarks}{}\paragraph*{{Pentaquarks}}\label{pentaquarks}

[[pentaquarks]]:

\begin{itemize}%
\item Kazuo Ghoroku, Akihiro Nakamura, Tomoki Taminato, Fumihiko Toyoda, \emph{Holographic Penta and Hepta Quark State in Confining Gauge Theories}, JHEP 1008:007,2010 (\href{https://arxiv.org/abs/1003.3698}{arxiv:1003.3698})

\end{itemize}
\hypertarget{glueball_physics}{}\subsubsection*{{Glueball physics}}\label{glueball_physics}

\begin{itemize}%
\item Kenji Suzuki, \emph{D0-D4 system and $QCD_{3+1}$}, Phys.Rev. D63 (2001) 084011 (\href{https://arxiv.org/abs/hep-th/0001057}{arXiv:hep-th/0001057})


\item S.S. Afonin, A.D. Katanaeva, \emph{Glueballs and deconfinement temperature in AdS/QCD} (\href{https://arxiv.org/abs/1809.07730}{arXiv:1809.07730})



\end{itemize}
\hypertarget{application_to_the_quarkgluon_plasma}{}\subsubsection*{{Application to the quark-gluon plasma}}\label{application_to_the_quarkgluon_plasma}

Application to the [[quark-gluon plasma]]:

Expositions and reviews include

\begin{itemize}%
\item Pavel Kovtun, \emph{Quark-Gluon Plasma and String Theory}, RHIC news (2009) (\href{http://www.bnl.gov/rhic/news/091107/story2.asp}{blog entry})


\item Makoto Natsuume, \emph{String theory and quark-gluon plasma} (\href{http://arxiv.org/abs/hep-ph/0701201}{arXiv:hep-ph/0701201})


\item [[Steven Gubser]], \emph{Using string theory to study the quark-gluon plasma: progress and perils} (\href{http://arxiv.org/abs/0907.4808}{arXiv:0907.4808})


\item Francesco Biagazzi, A. Cotrone, \emph{Holography and the quark-gluon plasma}, AIP Conference Proceedings 1492, 307 (2012) (\href{https://doi.org/10.1063/1.4763537}{doi:10.1063/1.4763537}, \href{http://cp3-origins.dk/content/movies/2013-01-14-bigazzi.pdf}{slides pdf})


\item Brambilla et al., section 9.2.2 of \emph{QCD and strongly coupled gauge theories: challenges and perspectives}, Eur Phys J C Part Fields. 2014; 74(10): 2981 (\href{https://link.springer.com/article/10.1140%2Fepjc%2Fs10052-014-2981-5}{doi:10.1140/epjc/s10052-014-2981-5})



\end{itemize}
Holographic discussion of the [[shear viscosity]] of the quark-gluon plasma goes back to

\begin{itemize}%
\item [[Giuseppe Policastro]], D.T. Son, A.O. Starinets, \emph{Shear viscosity of strongly coupled $N=4$ supersymmetric Yang-Mills plasma}, Phys. Rev. Lett.87:081601, 2001 (\href{http://arxiv.org/abs/hep-th/0104066}{arXiv:hep-th/0104066})

\end{itemize}
Other original articles include:

\begin{itemize}%
\item Brett McInnes, \emph{Holography of the Quark Matter Triple Point} (\href{http://arxiv.org/abs/0910.4456}{arXiv:0910.4456})


\item Hovhannes R. Grigoryan, Paul M. Hohler, Mikhail A. Stephanov, \emph{Towards the Gravity Dual of Quarkonium in the Strongly Coupled QCD Plasma} (\href{http://arxiv.org/abs/1003.1138}{arXiv:1003.1138})


\item Mansi Dhuria, Aalok Misra, \emph{Towards MQGP}, JHEP 1311 (2013) 001 (\href{https://arxiv.org/abs/1306.4339}{arXiv:1306.4339})



\end{itemize}
\hypertarget{application_to_lepton_anomalous_magnetic_moment}{}\subsubsection*{{Application to lepton anomalous magnetic moment}}\label{application_to_lepton_anomalous_magnetic_moment}

Application to [[anomalous magnetic moment]] of the [[muon]]:

\begin{itemize}%
\item Luigi Cappiello, \emph{What does Holographic QCD predict for anomalous $(g-2)_\mu$?}, 2015 (\href{https://agenda.infn.it/getFile.py/access?contribId=19&sessionId=5&resId=0&materialId=paper&confId=9430}{pdf})

\end{itemize}
\hypertarget{ReferencesApplicationToHiggsField}{}\subsubsection*{{Application to Higgs field}}\label{ReferencesApplicationToHiggsField}

Application to [[Higgs field]]:

\begin{itemize}%
\item Domenec Espriu, Alisa Katanaeva, \emph{Composite Higgs Models: a new holographic approach} (\href{https://arxiv.org/abs/1812.01523}{arXiv:1812.01523})

\end{itemize}
\hypertarget{application_to_angle_axions_and_strong_cpproblem}{}\subsubsection*{{Application to $\theta$-angle axions and strong CP-problem}}\label{application_to_angle_axions_and_strong_cpproblem}

Realization of [[axions]] and solution of [[strong CP-problem]]:

\begin{itemize}%
\item Francesco Bigazzi, Alessio Caddeo, Aldo L. Cotrone, Paolo Di Vecchia, Andrea Marzolla, \emph{The Holographic QCD Axion} (\href{https://arxiv.org/abs/1906.12117}{arXiv:1906.12117})

\end{itemize}
Discussion of the [[theta angle]] via the the [[graviphoton]] in the [[higher WZW term]] of the [[D4-brane]]:

\begin{itemize}%
\item Si-wen Li, around (3.1) of \emph{The theta-dependent Yang-Mills theory at finite temperature in a holographic description} (\href{https://arxiv.org/abs/1907.10277}{arXiv:1907.10277})

\end{itemize}
Discussion of the Witten-Veneziano mechanism

\begin{itemize}%
\item Josef Leutgeb, Anton Rebhan, \emph{Witten-Veneziano mechanism and pseudoscalar glueball-meson mixing in holographic QCD} (\href{https://arxiv.org/abs/1909.12352}{arxiv:1909.12352})

\end{itemize}
\hypertarget{application_to_the_qcd_trace_anomaly}{}\subsubsection*{{Application to the QCD trace anomaly}}\label{application_to_the_qcd_trace_anomaly}

Discussion of the [[QCD trace anomaly]]:

\begin{itemize}%
\item Jose L. Goity, Roberto C. Trinchero, \emph{Holographic models and the QCD trace anomaly}, Phys. Rev. D 86, 034033 – 2012 (\href{https://arxiv.org/abs/1204.6327}{arXiv:1204.6327})


\item Aalok Misra, Charles Gale, \emph{The QCD Trace Anomaly at Strong Coupling from M-Theory} (\href{https://arxiv.org/abs/1909.04062}{arXiv:1909.04062})



\end{itemize}
The [[QCD trace anomaly]] affects notably the [[equation of state]] of the [[quark-gluon plasma]], see there at \emph{\href{quark-gluon+plasma#ReferencesViaAdSCFT}{References -- Holographic description of quark-gluon plasma}}

\hypertarget{application_to_parton_distribution}{}\subsubsection*{{Application to parton distribution}}\label{application_to_parton_distribution}

\begin{itemize}%
\item Akira Watanabe, Takahiro Sawada, Mei Huang, \emph{Extraction of gluon distributions from structure functions at small x in holographic QCD} (\href{https://arxiv.org/abs/1910.10008}{arxiv:1910.10008})

\end{itemize}
\begin{quote}%
Understanding the nucleon structure is one of the most important research topics in fundamental science, and tremendous efforts have been done to deepen our knowledge over several decades. $[...]$ Since $[these]$ are highly nonperturbative physical quantities, in principle they are not calculable by the direct use of QCD. Furthermore, although there is available data, this has large errors. These facts cause the huge uncertainties which can be seen in the preceding studies based on the global QCD analysis.

In this work, we investigate the gluon distribution in nuclei by calculating the structure functions in the framework of holographic QCD, which is constructed based on the AdS/CFT correspondence.


\end{quote}
\hypertarget{ReferencesColourSuperconductivity}{}\subsubsection*{{Application to QCD phases}}\label{ReferencesColourSuperconductivity}

Application to [[phase of matter|phases]] of [[QCD]]

to [[colour superconductivity]]:

\begin{itemize}%
\item Kazem Bitaghsir Fadafan, Jesus Cruz Rojas, Nick Evans, \emph{A Holographic Description of Colour Superconductivity} (\href{https://arxiv.org/abs/1803.03107}{arXiv:1803.03107})

\end{itemize}
to [[confinement]]/[[quark-gluon plasma|deconfinement]] phase transiton:

\begin{itemize}%
\item Meng-Wei Li, Yi Yang, Pei-Hung Yuan \emph{Imprints of Early Universe on Gravitational Waves from First-Order Phase Transition in QCD} (\href{https://arxiv.org/abs/1812.09676}{arXiv:1812.09676})

\end{itemize}
See also

\begin{itemize}%
\item Yosuke Imamura, \emph{Baryon Mass and Phase Transitions in Large N Gauge Theory}, Prog. Theor. Phys. 100 (1998) 1263-1272 (\href{https://arxiv.org/abs/hep-th/9806162}{arxiv:hep-th/9806162})


\item Varun Sethi, \emph{A study of phases in two flavour holographic QCD} (\href{https://arxiv.org/abs/1906.10932}{arXiv:1906.10932})


\item Riccardo Argurio, Matteo Bertolini, Francesco Bigazzi, Aldo L. Cotrone, Pierluigi Niro, \emph{QCD domain walls, Chern-Simons theories and holography}, J. High Energ. Phys. (2018) 2018: 90 (\href{https://arxiv.org/abs/1806.08292}{arXiv:1806.08292})



\end{itemize}
\hypertarget{application_to_defects}{}\subsubsection*{{Application to defects}}\label{application_to_defects}

Application to QCD [[QFT with defects|with defects]]:

\begin{itemize}%
\item Alexander Gorsky, Valentin Zakharov, Ariel Zhitnitsky, \emph{On Classification of QCD defects via holography}, Phys. Rev. D79:106003, 2009 (\href{https://arxiv.org/abs/0902.1842}{arxiv:0902.1842})

\end{itemize}
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