\documentclass[12pt,titlepage]{article} \usepackage{amsmath} \usepackage{mathrsfs} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsthm} \usepackage{mathtools} \usepackage{graphicx} \usepackage{color} \usepackage{ucs} \usepackage[utf8x]{inputenc} \usepackage{xparse} \usepackage{hyperref} %----Macros---------- % % Unresolved issues: % % \righttoleftarrow % \lefttorightarrow % % \color{} with HTML colorspec % \bgcolor % \array with options (without options, it's equivalent to the matrix environment) % Of the standard HTML named colors, white, black, red, green, blue and yellow % are predefined in the color package. Here are the rest. \definecolor{aqua}{rgb}{0, 1.0, 1.0} \definecolor{fuschia}{rgb}{1.0, 0, 1.0} \definecolor{gray}{rgb}{0.502, 0.502, 0.502} \definecolor{lime}{rgb}{0, 1.0, 0} \definecolor{maroon}{rgb}{0.502, 0, 0} \definecolor{navy}{rgb}{0, 0, 0.502} \definecolor{olive}{rgb}{0.502, 0.502, 0} \definecolor{purple}{rgb}{0.502, 0, 0.502} \definecolor{silver}{rgb}{0.753, 0.753, 0.753} \definecolor{teal}{rgb}{0, 0.502, 0.502} % Because of conflicts, \space and \mathop are converted to % \itexspace and \operatorname during preprocessing. % itex: \space{ht}{dp}{wd} % % Height and baseline depth measurements are in units of tenths of an ex while % the width is measured in tenths of an em. \makeatletter \newdimen\itex@wd% \newdimen\itex@dp% \newdimen\itex@thd% \def\itexspace#1#2#3{\itex@wd=#3em% \itex@wd=0.1\itex@wd% \itex@dp=#2ex% \itex@dp=0.1\itex@dp% \itex@thd=#1ex% \itex@thd=0.1\itex@thd% \advance\itex@thd\the\itex@dp% \makebox[\the\itex@wd]{\rule[-\the\itex@dp]{0cm}{\the\itex@thd}}} \makeatother % \tensor and \multiscript \makeatletter \newif\if@sup \newtoks\@sups \def\append@sup#1{\edef\act{\noexpand\@sups={\the\@sups #1}}\act}% \def\reset@sup{\@supfalse\@sups={}}% \def\mk@scripts#1#2{\if #2/ \if@sup ^{\the\@sups}\fi \else% \ifx #1_ \if@sup ^{\the\@sups}\reset@sup \fi {}_{#2}% \else \append@sup#2 \@suptrue \fi% \expandafter\mk@scripts\fi} \def\tensor#1#2{\reset@sup#1\mk@scripts#2_/} \def\multiscripts#1#2#3{\reset@sup{}\mk@scripts#1_/#2% \reset@sup\mk@scripts#3_/} \makeatother % \slash \makeatletter \newbox\slashbox \setbox\slashbox=\hbox{$/$} \def\itex@pslash#1{\setbox\@tempboxa=\hbox{$#1$} \@tempdima=0.5\wd\slashbox \advance\@tempdima 0.5\wd\@tempboxa \copy\slashbox \kern-\@tempdima \box\@tempboxa} \def\slash{\protect\itex@pslash} \makeatother % math-mode versions of \rlap, etc % from Alexander Perlis, "A complement to \smash, \llap, and lap" % http://math.arizona.edu/~aprl/publications/mathclap/ \def\clap#1{\hbox to 0pt{\hss#1\hss}} \def\mathllap{\mathpalette\mathllapinternal} \def\mathrlap{\mathpalette\mathrlapinternal} \def\mathclap{\mathpalette\mathclapinternal} \def\mathllapinternal#1#2{\llap{$\mathsurround=0pt#1{#2}$}} \def\mathrlapinternal#1#2{\rlap{$\mathsurround=0pt#1{#2}$}} \def\mathclapinternal#1#2{\clap{$\mathsurround=0pt#1{#2}$}} % Renames \sqrt as \oldsqrt and redefine root to result in \sqrt[#1]{#2} \let\oldroot\root \def\root#1#2{\oldroot #1 \of{#2}} \renewcommand{\sqrt}[2][]{\oldroot #1 \of{#2}} % Manually declare the txfonts symbolsC font \DeclareSymbolFont{symbolsC}{U}{txsyc}{m}{n} \SetSymbolFont{symbolsC}{bold}{U}{txsyc}{bx}{n} \DeclareFontSubstitution{U}{txsyc}{m}{n} % Manually declare the stmaryrd font \DeclareSymbolFont{stmry}{U}{stmry}{m}{n} \SetSymbolFont{stmry}{bold}{U}{stmry}{b}{n} % Manually declare the MnSymbolE font \DeclareFontFamily{OMX}{MnSymbolE}{} \DeclareSymbolFont{mnomx}{OMX}{MnSymbolE}{m}{n} \SetSymbolFont{mnomx}{bold}{OMX}{MnSymbolE}{b}{n} \DeclareFontShape{OMX}{MnSymbolE}{m}{n}{ <-6> MnSymbolE5 <6-7> MnSymbolE6 <7-8> MnSymbolE7 <8-9> MnSymbolE8 <9-10> MnSymbolE9 <10-12> MnSymbolE10 <12-> MnSymbolE12}{} % Declare specific arrows from txfonts without loading the full package \makeatletter \def\re@DeclareMathSymbol#1#2#3#4{% \let#1=\undefined \DeclareMathSymbol{#1}{#2}{#3}{#4}} \re@DeclareMathSymbol{\neArrow}{\mathrel}{symbolsC}{116} \re@DeclareMathSymbol{\neArr}{\mathrel}{symbolsC}{116} \re@DeclareMathSymbol{\seArrow}{\mathrel}{symbolsC}{117} \re@DeclareMathSymbol{\seArr}{\mathrel}{symbolsC}{117} \re@DeclareMathSymbol{\nwArrow}{\mathrel}{symbolsC}{118} \re@DeclareMathSymbol{\nwArr}{\mathrel}{symbolsC}{118} \re@DeclareMathSymbol{\swArrow}{\mathrel}{symbolsC}{119} \re@DeclareMathSymbol{\swArr}{\mathrel}{symbolsC}{119} \re@DeclareMathSymbol{\nequiv}{\mathrel}{symbolsC}{46} \re@DeclareMathSymbol{\Perp}{\mathrel}{symbolsC}{121} \re@DeclareMathSymbol{\Vbar}{\mathrel}{symbolsC}{121} \re@DeclareMathSymbol{\sslash}{\mathrel}{stmry}{12} \re@DeclareMathSymbol{\bigsqcap}{\mathop}{stmry}{"64} \re@DeclareMathSymbol{\biginterleave}{\mathop}{stmry}{"6} \re@DeclareMathSymbol{\invamp}{\mathrel}{symbolsC}{77} \re@DeclareMathSymbol{\parr}{\mathrel}{symbolsC}{77} \makeatother % \llangle, \rrangle, \lmoustache and \rmoustache from MnSymbolE \makeatletter \def\Decl@Mn@Delim#1#2#3#4{% \if\relax\noexpand#1% \let#1\undefined \fi \DeclareMathDelimiter{#1}{#2}{#3}{#4}{#3}{#4}} \def\Decl@Mn@Open#1#2#3{\Decl@Mn@Delim{#1}{\mathopen}{#2}{#3}} \def\Decl@Mn@Close#1#2#3{\Decl@Mn@Delim{#1}{\mathclose}{#2}{#3}} \Decl@Mn@Open{\llangle}{mnomx}{'164} \Decl@Mn@Close{\rrangle}{mnomx}{'171} \Decl@Mn@Open{\lmoustache}{mnomx}{'245} \Decl@Mn@Close{\rmoustache}{mnomx}{'244} \makeatother % Widecheck \makeatletter \DeclareRobustCommand\widecheck[1]{{\mathpalette\@widecheck{#1}}} \def\@widecheck#1#2{% \setbox\z@\hbox{\m@th$#1#2$}% \setbox\tw@\hbox{\m@th$#1% \widehat{% \vrule\@width\z@\@height\ht\z@ \vrule\@height\z@\@width\wd\z@}$}% \dp\tw@-\ht\z@ \@tempdima\ht\z@ \advance\@tempdima2\ht\tw@ \divide\@tempdima\thr@@ \setbox\tw@\hbox{% \raise\@tempdima\hbox{\scalebox{1}[-1]{\lower\@tempdima\box \tw@}}}% {\ooalign{\box\tw@ \cr \box\z@}}} \makeatother % \mathraisebox{voffset}[height][depth]{something} \makeatletter \NewDocumentCommand\mathraisebox{moom}{% \IfNoValueTF{#2}{\def\@temp##1##2{\raisebox{#1}{$\m@th##1##2$}}}{% \IfNoValueTF{#3}{\def\@temp##1##2{\raisebox{#1}[#2]{$\m@th##1##2$}}% }{\def\@temp##1##2{\raisebox{#1}[#2][#3]{$\m@th##1##2$}}}}% \mathpalette\@temp{#4}} \makeatletter % udots (taken from yhmath) \makeatletter \def\udots{\mathinner{\mkern2mu\raise\p@\hbox{.} \mkern2mu\raise4\p@\hbox{.}\mkern1mu \raise7\p@\vbox{\kern7\p@\hbox{.}}\mkern1mu}} \makeatother %% Fix array \newcommand{\itexarray}[1]{\begin{matrix}#1\end{matrix}} %% \itexnum is a noop \newcommand{\itexnum}[1]{#1} %% Renaming existing commands \newcommand{\underoverset}[3]{\underset{#1}{\overset{#2}{#3}}} \newcommand{\widevec}{\overrightarrow} \newcommand{\darr}{\downarrow} \newcommand{\nearr}{\nearrow} \newcommand{\nwarr}{\nwarrow} \newcommand{\searr}{\searrow} \newcommand{\swarr}{\swarrow} \newcommand{\curvearrowbotright}{\curvearrowright} \newcommand{\uparr}{\uparrow} \newcommand{\downuparrow}{\updownarrow} \newcommand{\duparr}{\updownarrow} \newcommand{\updarr}{\updownarrow} \newcommand{\gt}{>} \newcommand{\lt}{<} \newcommand{\map}{\mapsto} \newcommand{\embedsin}{\hookrightarrow} \newcommand{\Alpha}{A} \newcommand{\Beta}{B} \newcommand{\Zeta}{Z} \newcommand{\Eta}{H} \newcommand{\Iota}{I} \newcommand{\Kappa}{K} \newcommand{\Mu}{M} \newcommand{\Nu}{N} \newcommand{\Rho}{P} \newcommand{\Tau}{T} \newcommand{\Upsi}{\Upsilon} \newcommand{\omicron}{o} \newcommand{\lang}{\langle} \newcommand{\rang}{\rangle} \newcommand{\Union}{\bigcup} \newcommand{\Intersection}{\bigcap} \newcommand{\Oplus}{\bigoplus} \newcommand{\Otimes}{\bigotimes} \newcommand{\Wedge}{\bigwedge} \newcommand{\Vee}{\bigvee} \newcommand{\coproduct}{\coprod} \newcommand{\product}{\prod} \newcommand{\closure}{\overline} \newcommand{\integral}{\int} \newcommand{\doubleintegral}{\iint} \newcommand{\tripleintegral}{\iiint} \newcommand{\quadrupleintegral}{\iiiint} \newcommand{\conint}{\oint} \newcommand{\contourintegral}{\oint} \newcommand{\infinity}{\infty} \newcommand{\bottom}{\bot} \newcommand{\minusb}{\boxminus} \newcommand{\plusb}{\boxplus} \newcommand{\timesb}{\boxtimes} \newcommand{\intersection}{\cap} \newcommand{\union}{\cup} \newcommand{\Del}{\nabla} \newcommand{\odash}{\circleddash} \newcommand{\negspace}{\!} \newcommand{\widebar}{\overline} \newcommand{\textsize}{\normalsize} \renewcommand{\scriptsize}{\scriptstyle} \newcommand{\scriptscriptsize}{\scriptscriptstyle} \newcommand{\mathfr}{\mathfrak} \newcommand{\statusline}[2]{#2} \newcommand{\tooltip}[2]{#2} \newcommand{\toggle}[2]{#2} % Theorem Environments \theoremstyle{plain} \newtheorem{theorem}{Theorem} \newtheorem{lemma}{Lemma} \newtheorem{prop}{Proposition} \newtheorem{cor}{Corollary} \newtheorem*{utheorem}{Theorem} \newtheorem*{ulemma}{Lemma} \newtheorem*{uprop}{Proposition} \newtheorem*{ucor}{Corollary} \theoremstyle{definition} \newtheorem{defn}{Definition} \newtheorem{example}{Example} \newtheorem*{udefn}{Definition} \newtheorem*{uexample}{Example} \theoremstyle{remark} \newtheorem{remark}{Remark} \newtheorem{note}{Note} \newtheorem*{uremark}{Remark} \newtheorem*{unote}{Note} %------------------------------------------------------------------- \begin{document} %------------------------------------------------------------------- \section*{intersecting D-brane model} \hypertarget{context}{}\subsubsection*{{Context}}\label{context} \hypertarget{string_theory}{}\paragraph*{{String theory}}\label{string_theory} [[!include string theory - contents]] \hypertarget{fields_and_quanta}{}\paragraph*{{Fields and quanta}}\label{fields_and_quanta} [[!include fields and quanta - table]] \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{bottomup_and_topdown_approaches}{Bottom-up and Top-down approaches}\dotfill \pageref*{bottomup_and_topdown_approaches} \linebreak \noindent\hyperlink{properties}{Properties}\dotfill \pageref*{properties} \linebreak \noindent\hyperlink{ChiralFermions}{Chiral fermions}\dotfill \pageref*{ChiralFermions} \linebreak \noindent\hyperlink{GenerationsOfFermions}{Generations of fermions}\dotfill \pageref*{GenerationsOfFermions} \linebreak \noindent\hyperlink{yukawa_couplings}{Yukawa couplings}\dotfill \pageref*{yukawa_couplings} \linebreak \noindent\hyperlink{HiggsMechanism}{Higgs mechanism}\dotfill \pageref*{HiggsMechanism} \linebreak \noindent\hyperlink{Orientifolding}{RR-Tadpole cancellation and Orientifolding}\dotfill \pageref*{Orientifolding} \linebreak \noindent\hyperlink{IntersectionOfD6WithO8}{Intersections of D6s with D8/O8s}\dotfill \pageref*{IntersectionOfD6WithO8} \linebreak \noindent\hyperlink{relation_to_mtheory_on_manifolds}{Relation to M-theory on $G_2$-manifolds}\dotfill \pageref*{relation_to_mtheory_on_manifolds} \linebreak \noindent\hyperlink{Cosmology}{Cosmology and Holography}\dotfill \pageref*{Cosmology} \linebreak \noindent\hyperlink{ComputerScanOfGepnerModelCompactifications}{Computer scan of Gepner-model compactifications}\dotfill \pageref*{ComputerScanOfGepnerModelCompactifications} \linebreak \noindent\hyperlink{examples}{Examples}\dotfill \pageref*{examples} \linebreak \noindent\hyperlink{intersecting_d6brane_models}{Intersecting D6-brane models}\dotfill \pageref*{intersecting_d6brane_models} \linebreak \noindent\hyperlink{IntersectingD4BraneModels}{Intersecting D4-brane models}\dotfill \pageref*{IntersectingD4BraneModels} \linebreak \noindent\hyperlink{references}{References}\dotfill \pageref*{references} \linebreak \noindent\hyperlink{general}{General}\dotfill \pageref*{general} \linebreak \noindent\hyperlink{the_landscape_of_models}{The landscape of models}\dotfill \pageref*{the_landscape_of_models} \linebreak \noindent\hyperlink{ReferencesDetailedRealisticModels}{Detailed realistic models}\dotfill \pageref*{ReferencesDetailedRealisticModels} \linebreak \noindent\hyperlink{ReferencesLiftToMTheory}{Lift to M-theory}\dotfill \pageref*{ReferencesLiftToMTheory} \linebreak \noindent\hyperlink{ReferencesCosmology}{Cosmology}\dotfill \pageref*{ReferencesCosmology} \linebreak \noindent\hyperlink{experimental_tests}{Experimental tests}\dotfill \pageref*{experimental_tests} \linebreak \hypertarget{idea}{}\subsection*{{Idea}}\label{idea} In [[string phenomenology]] for [[type IIA string theory]], quasi-realistic [[model (physics)|models]] (i.e. close to the [[standard model of particle physics]], or an [[MSSM]]) may be obtained by [[KK-compactifications]] from the 10-[[dimensions]] down to 4d with configurations of [[D6-branes]] which fill all of 4d spacetime and [[brane intersection|intersect]] in a certain way in the 6-dimensional [[fiber]] space. \begin{quote}% graphics grabbed from \hyperlink{Uranga12a}{Uranga 12a, p. 12} \end{quote} The [[Chan-Paton gauge field]] on the [[D6-branes]] yields the [[gauge fields]] in 4d, and the precise [[brane intersection|intersection]] pattern determines the effective [[fundamental particle]] content in 4d. See also at [[string phenomenology]] the section \emph{\href{string+phenomenology#ModelsInTypeIIWithIntersectingBranes}{Models in type II with intersecting branes}}. \hypertarget{bottomup_and_topdown_approaches}{}\subsection*{{Bottom-up and Top-down approaches}}\label{bottomup_and_topdown_approaches} One distinguishes [[bottom-up and top-down model building]] strategies: \begin{quote}% snippet grabbed from \hyperlink{AldazabalIbanezQuevedoUranga00}{Aldazabal-Ibáñez-Quevedo-Uranga 00} \end{quote} \hypertarget{properties}{}\subsection*{{Properties}}\label{properties} \hypertarget{ChiralFermions}{}\subsubsection*{{Chiral fermions}}\label{ChiralFermions} One of the most striking special properties of the [[standard model of particle physics]] is that its content of [[fermionic]] [[fundamental particles]] is ``[[chiral fermion|chiral]]'', in that the left and right [[Weyl spinor]]-components of the would-be [[Dirac spinor]]-representation of the [[quarks]], [[electrons]] and [[neutrinos]] couple \emph{differently} to the [[gauge fields]] (for review see e.g. \hyperlink{IbanezUranga12}{Ibanez-Uranga 12, section 1.1}). The observation that such [[Weyl spinor|chiral fermions]] do indeed appear when [[D6-branes]] [[brane intersection|intersect]] at an angle on an $\mathbb{R}^{3,1}$ is due to (\hyperlink{BerkoozDouglasLeigh96}{Berkooz-Douglas-Leigh 96}), see also (\hyperlink{AFIRU00}{AFIRU 00, section 4}, \hyperlink{BCLS05}{BCLS 05, section 2.3}). For review with an eye towards [[RR-field tadpole cancellation]] on [[toroidal orbifold|toroidal]] [[orientifolds]] see also \hyperlink{ForsteHoneckerSchreyer01}{Forste-Honecker-Schreyer 01}, \hyperlink{Honecker01}{Honecker 01, Sec. 2}, \hyperlink{Honecker02}{Honecker 02}. \begin{quote}% graphics grabbed from \hyperlink{IbanezUranga12}{Ibáñez-Uranga 12} \end{quote} Vague review is in (\hyperlink{IbanezUranga12}{Ibáñez-Uranga 12, section 10.2.1}, \hyperlink{Uranga12a}{Uranga 12a, section 2.3}). The lift of this situation to [[M-theory on G2-manifolds]] is discussed in (\hyperlink{BerglundBrandhuber02}{Berglund-Brandhuber 02}, \hyperlink{BourjailyEspahbodi08}{Bourjaily-Espahbodi 08}). \hypertarget{GenerationsOfFermions}{}\subsubsection*{{Generations of fermions}}\label{GenerationsOfFermions} While (presently) intersecting D-brane models don't explain why there are \emph{precisely} 3 [[generations of fundamental particles]] in the [[standard model of particle physics]], they do have the property that generically any such model does feature several [[generations of fundamental particles]]. The reason is that in these models there is one copy of a set of fundamental particles at each intersection point of two 3-manifolds (the internal part of the D6-branes) in a compact 6-dimensional space, and generically these intersection numbers are greater than one and hence induce a finite number of [[generations of fundamental particles|generations]] (\hyperlink{BCLS05}{BCLS 05, section 2.3}, \hyperlink{IbanezUranga12}{Ibanez-Uranga 12, p. 307}, \hyperlink{Uranga12a}{Uranga 12a, p. 12}): \begin{quote}% graphics grabbed from \hyperlink{Uranga12a}{Uranga 12a, p. 13} \end{quote} \hypertarget{yukawa_couplings}{}\subsubsection*{{Yukawa couplings}}\label{yukawa_couplings} In [[intersecting D-brane models]] [[Yukawa couplings]] are encoded by [[worldsheet instantons]] of open strings stretching between the [[brane intersection|intersecting]] [[D-branes]] (see \hyperlink{Marchesano03}{Marchesano 03, Section 7.5}). Mathematically this is encoded by [[derived hom-spaces]] in a [[Fukaya category]] (see \hyperlink{Marchesano03}{Marchesano 03, Section 7.5}). $\backslash$begin\{center\} $\backslash$end\{center\} \begin{quote}% table grabbed from \hyperlink{Marchesano03}{Marchesano 03} \end{quote} Realistic [[Yukawa couplings]] and [[fermion]] [[masses]] in an [[MSSM]] [[Pati-Salam GUT model]] with 3 [[generations of fermions]] realized on [[intersecting D-brane model|intersecting]] [[D6-branes]] [[KK-compactification|KK-compactified]] on a [[toroidal orbifold]] $T^6\sslash (\mathbb{Z}_2 \times \mathbb{Z}_2)$ are claimed in in \hyperlink{Mayes19}{Mayes 19}, \hyperlink{GemillHowingtonMayes19}{Gemill-Howington-Mayes 19}, based on \hyperlink{ChenLiMayesNanopoulos07a}{Chen-Li-Mayes-Nanopoulos 07a}, \hyperlink{ChenLiMayesNanopoulos07b}{Chen-Li-Mayes-Nanopoulos 07b}. $\backslash$linebreak \hypertarget{HiggsMechanism}{}\subsubsection*{{Higgs mechanism}}\label{HiggsMechanism} The [[Higgs mechanism]] naturally arises in [[intersecting D-brane models]]: The [[Higgs field]] appears here as the [[scalar field]] that witnesses in [[perturbative quantum field theory|perturbation theory]] the process of \emph{brane recombination} at the intersection locus of the D-branes (\hyperlink{CremadesIbanezMarchesano02}{Cremades-Ibanez-Marchesano 02, section 7}): Further developments in \hyperlink{IbanezMarchesanoRabadan01}{Ibanez-Marchesano-Rabadan 01}, \hyperlink{HebeckerKnochelWeigand13}{Hebecker-Knochel-Weigand 13} and specifically via [[string field theory]] in \hyperlink{HINSS18}{HINSS 18}. For review see \hyperlink{IbanezUranga12}{Ibanez-Uranga 12, fig 10.2}: $\backslash$linebreak \hypertarget{Orientifolding}{}\subsubsection*{{RR-Tadpole cancellation and Orientifolding}}\label{Orientifolding} Consistent intersecting D-brane models have to be in [[type I string theory]], or generally in [[type II string theory]] with [[orientifold]] backgrounds, to achieve [[RR-field tadpole cancellation]]. This is a key consistency condition in intersecting D-brane model building (e.g. \hyperlink{BCLS05}{BCLS 05, section 2.4}, \hyperlink{IbanezUranga12}{Ibanez-Uranga 12, section 4.4}) [[!include RR-field tadpole cancellation on toroidal orientifolds -- table]] \hypertarget{IntersectionOfD6WithO8}{}\subsubsection*{{Intersections of D6s with D8/O8s}}\label{IntersectionOfD6WithO8} A [[black brane|black]] [[D6-brane]] may end on a [[black brane|black]] [[NS5-brane]], and in fact each [[black brane|brane]] [[NS5-brane]] at a non-trivial [[ADE singularity]] has to be the junction of two [[black brane|black]] [[D6-branes]]. For details see at \emph{\href{NS5-brane#D6BranesEndingOnNS5Branes}{D6-branes ending on NS5-branes}}. \begin{quote}% from \hyperlink{GKSTY02}{GKSTY 02} \end{quote} If in addition the [[black brane|black]] [[NS5-brane]] sits at an [[O8-plane]], hence at the [[orientifold]] [[fixed point]]-locus (see \hyperlink{Orientifolding}{above}), then in the ordinary $\mathbb{Z}/2$-[[quotient]] it appears as a ``[[half-brane]]'' with only one copy of [[D6-branes]] ending on it: \begin{quote}% from \hyperlink{GKSTY02}{GKSTY 02} \end{quote} (In \hyperlink{HananyZaffaroni99}{Hanany-Zaffaroni 99} this is interpreted in terms of the [[`t Hooft-Polyakov monopole]].) The lift to [[M-theory]] of this situation is an [[M5-brane]] intersecting an [[M9-brane]]: \begin{quote}% from \hyperlink{GKSTY02}{GKSTY 02} \end{quote} Alternatively, the [[O8-plane]] may intersect the [[black brane|black]] [[D6-branes]] away from the [[black brane|black]] [[NS5-brane]]: \begin{quote}% from \hyperlink{HKLY15}{HKLY 15} \end{quote} In general, some of the NS5 sit away from the [[O8-plane]], while some sit on top of it: \begin{quote}% from \hyperlink{HananyZaffaroni98}{Hanany-Zaffaroni 98} \end{quote} \hypertarget{relation_to_mtheory_on_manifolds}{}\subsubsection*{{Relation to M-theory on $G_2$-manifolds}}\label{relation_to_mtheory_on_manifolds} Lift to [[M-theory on G2-manifolds]] (e.g. [[G2-MSSM]]): see references \hyperlink{ReferencesLiftToMTheory}{below} $\,$ \hypertarget{Cosmology}{}\subsubsection*{{Cosmology and Holography}}\label{Cosmology} Since the [[near horizon geometry]] of [[BPS state|BPS]] [[black branes]] is conformal to the [[Cartesian product]] of [[anti de Sitter spaces]] with the unit $n$-sphere around the brane, the [[cosmology]] of intersecting D-brane models realizes the [[observable universe]] on the [[asymptotic boundary]] of an \emph{approximately} [[anti de Sitter spacetime]] (see for instance \hyperlink{Kaloper04}{Kaloper 04}, \hyperlink{FlachiMinamitsuji09}{Flachi-Minamitsuji 09}). The basic structure is hence that of \emph{[[Randall-Sundrum models]]}, but details differ, such as notably in \emph{warped throat} geometries, see \hyperlink{Uranga05}{Uranga 05, section 18}. These warped throat models go back to \hyperlink{KlebanovStrassler00}{Klebanov-Strassler 00} which discusses aspects of [[confinement]] in [[Yang-Mills theory]] on conincident ordinary and \emph{[[fractional D-brane|fractional]]} [[D3-branes]] at the [[singularity]] of a warped [[conifold]]. See also \hyperlink{KlebanovWitten98}{Klebanov-Witten 98}. \begin{quote}% snippet grabbed from \hyperlink{Uranga05}{Uranga 05, section 18} here: ``RS''=[[Randall-Sundrum model]]; ``KS''=\hyperlink{KlebanovStrassler00}{Klebanov-Strassler 00} \end{quote} In particular this means that [[AdS-CFT duality]] applies in \emph{some approximation} to intersecting D-brane models (e.g. \hyperlink{Soda10}{Soda 10}, \hyperlink{GHMO16}{GHMO 16}), thus allowing to compute, to some approximation, [[non-perturbative effects]] in the [[Yang-Mills theory]] on the intersecting branes in terms of [[gravity]] on the ambient warped throat $\sim$ [[anti de Sitter spacetime|AdS]] (\hyperlink{KlebanovStrassler00}{Klebanov-Strassler 00, section 6}) Such approximate versions of [[AdS-CFT]] for gauge theories realized on intersecting D-branes are used for instance to estimate [[non-perturbative effects]] in [[QCD]], such as the [[shear viscosity]] of the [[quark-gluon plasma]] (see the references \href{quark-gluon+plasma#ReferencesViaAdSCFT}{there}). See at \emph{[[AdS-QCD correspondence]]} for more on this. $\,$ \hypertarget{ComputerScanOfGepnerModelCompactifications}{}\subsubsection*{{Computer scan of Gepner-model compactifications}}\label{ComputerScanOfGepnerModelCompactifications} Discussion of [[string phenomenology]] of [[intersecting D-brane models]] [[KK-compactification|KK-compactified]] with non-geometric [[fibers]] such that the would-be string [[sigma-models]] with these [[target spaces]] are in fact [[Gepner models]] (in the sense of \emph{\href{https://www.physicsforums.com/insights/spectral-standard-model-string-compactifications/}{Spectral Standard Model and String Compactifications}}) is in (\hyperlink{DijkstraHuiszoonSchellekens04a}{Dijkstra-Huiszoon-Schellekens 04a}, \hyperlink{DijkstraHuiszoonSchellekens04a}{Dijkstra-Huiszoon-Schellekens 04b}): \begin{quote}% A plot of [[standard model of particle physics|standard model]]-like [[coupling constants]] in a computer scan of [[Gepner model]]-[[KK-compactification]] of [[intersecting D-brane models]] according to \hyperlink{DijkstraHuiszoonSchellekens04b}{Dijkstra-Huiszoon-Schellekens 04b}. The blue dot indicates the couplings in $SU(5)$-[[GUT]] theory. The faint lines are NOT drawn by hand, but reflect increased density of Gepner models as seen by the computer scan. \end{quote} \hypertarget{examples}{}\subsection*{{Examples}}\label{examples} \hypertarget{intersecting_d6brane_models}{}\subsubsection*{{Intersecting D6-brane models}}\label{intersecting_d6brane_models} (\ldots{}) \begin{itemize}% \item S. Ishihara, H. Kataoka, Hikaru Sato, \emph{$D=4$, $N=1$, Type IIA Orientifolds}, Phys. Rev. D60 (1999) 126005 (\href{https://arxiv.org/abs/hep-th/9908017}{arXiv:hep-th/9908017}) \end{itemize} (\ldots{}) \hypertarget{IntersectingD4BraneModels}{}\subsubsection*{{Intersecting D4-brane models}}\label{IntersectingD4BraneModels} Only [[D4-branes]]: \begin{itemize}% \item D. Bailin, G. V. Kraniotis, A. Love, \emph{Standard-like models from intersecting D4-branes}, Phys. Lett. B530 (2002) 202-209 (\href{https://arxiv.org/abs/hep-th/0108131}{arXiv:hep-th/0108131}) \item H. Kataoka, M. Shimojo, \emph{$SU(3) \times SU(2) \times U(1)$ Chiral Models from Intersecting D4-/D5-branes}, Progress of Theoretical Physics, Volume 107, Issue 6, June 2002, Pages 1291–1296 (\href{https://arxiv.org/abs/hep-th/0112247}{arXiv:hep-th/0112247}, \href{https://doi.org/10.1143/PTP.107.1291}{doi:10.1143/PTP.107.1291}) \item D. Bailin, \emph{Standard-like models from D-branes}, J Phys (2003) 60: 199 (\href{https://arxiv.org/abs/hep-th/0210227}{arXiv:hep-th/0210227}) \item D. Bailin, G. V. Kraniotis, A. Love, \emph{New Standard-like Models from Intersecting D4-Branes}, Phys. Lett. B547 (2002) 43-50 (\href{https://arxiv.org/abs/hep-th/0208103}{arXiv:hep-th/0208103}) \end{itemize} [[D4-D8 brane bound states]]: give the [[Witten-Sakai-Sugimoto model]] for [[holographic QCD]] \begin{quote}% graphics grabbed from \href{WSS-model#Erlich09}{Erlich 09, section 1.1} \end{quote} \begin{quote}% graphics grabbed from \href{WSS-model#Rebhan14}{Rebhan 14} \end{quote} (\ldots{}) \hypertarget{references}{}\subsection*{{References}}\label{references} \hypertarget{general}{}\subsubsection*{{General}}\label{general} The [[bottom-up model building|bottom-up approach]] to intersecting D-brane model building was initiated in \begin{itemize}% \item G. Aldazabal, [[Luis Ibáñez]], F. Quevedo, [[Angel Uranga]], \emph{D-Branes at Singularities : A Bottom-Up Approach to the String Embedding of the Standard Model}, JHEP 0008:002 2000 (\href{http://xxx.lanl.gov/abs/hep-th/0005067}{arXiv:hep-th/0005067}) \end{itemize} The observation that [[Weyl spinor|chiral fermions]] appear when [[D6-branes]] intersect at an angle is due to \begin{itemize}% \item [[Micha Berkooz]], [[Michael Douglas]], [[Robert Leigh]], \emph{Branes Intersecting at Angles}, Nucl.Phys.B480:265-278, 1996 (\href{https://arxiv.org/abs/hep-th/9606139}{arXiv:hep-th/9606139}) \end{itemize} development for [[toroidal orbifold|toroidal]] [[orientifolds]] is due to \begin{itemize}% \item Stefan Forste, [[Gabriele Honecker]], Ralph Schreyer, \emph{Orientifolds with branes at angles}, JHEP 0106:004, 2001 (\href{https://arxiv.org/abs/hep-th/0105208}{arXiv:hep-th/0105208}) \item [[Gabriele Honecker]], \emph{Non-supersymmetric Orientifolds with D-branes at Angles}, Fortsch.Phys. 50 (2002) 896-902 (\href{https://arxiv.org/abs/hep-th/0112174}{arXiv:hep-th/0112174}) \item [[Gabriele Honecker]], \emph{Non-supersymmetric orientifolds and chiral fermions from intersecting D6- and D8-branes}, thesis 2002 ([[HoneckerIntersectingDBraneModels02.pdf:file]]) \end{itemize} Review includes \begin{itemize}% \item G. Aldazabal, [[Luis Ibáñez]], F. Quevedo, \emph{On Realistic Brane Worlds from Type I Strings} (\href{https://arxiv.org/abs/hep-ph/0005033}{arXiv:hep-ph/0005033}) \item [[Fernando Marchesano]], \emph{Intersecting D-brane Models} (\href{https://arxiv.org/abs/hep-th/0307252}{arXiv:hep-th/0307252}) \item [[Ralph Blumenhagen]], [[Mirjam Cvetic]], Paul Langacker, [[Gary Shiu]], \emph{Towards Realistic Intersecting D-Brane Models}, Ann. Rev. Nucl. Part. Sci. 55:71-139, 2005 (\href{http://arxiv.org/abs/hep-th/0502005}{arXiv:hep-th/0502005}) \end{itemize} A textbook account is \begin{itemize}% \item [[Luis Ibáñez]], [[Angel Uranga]], \emph{[[String Theory and Particle Physics -- An Introduction to String Phenomenology]]}, Cambridge 2012 \end{itemize} Some chapters of which appear separately: for [[D6-branes]]: \begin{itemize}% \item \hyperlink{AldazabalIbanezQuevedoUranga00}{Aldazabal-Ibanez-Quevedo-Uranga 00, section 10.2} \item [[Angel Uranga]], \emph{Model building in IIA: Intersecting brane worlds}, 2012 (\href{http://scgp.stonybrook.edu/wp-content/uploads/2012/05/Uranga-Lecture-Notes-1.pdf}{pdf}, [[Uranga12.pdf:file]]) \end{itemize} for [[D7-branes]]: \begin{itemize}% \item [[Angel Uranga]], \emph{Model building in type IIB string theory}, 2012 (\href{http://scgp.stonybrook.edu/wp-content/uploads/2012/05/Uranga-Lecture-Notes-2.pdf}{pdf}) \item Anshuman Maharana, [[Eran Palti]], \emph{Models of Particle Physics from Type IIB String Theory and F-theory: A Review} (\href{http://arxiv.org/abs/1212.0555}{arXiv:1212.0555}) \end{itemize} Discussion of the [[Higgs mechanism]] in intersecting D-brane models: \begin{itemize}% \item [[Luis Ibáñez]], [[Fernando Marchesano]], R. Rabadan, section 7 of \emph{Getting just the Standard Model at Intersecting Branes}, JHEP 0111:002, 2001 (\href{https://arxiv.org/abs/hep-th/0105155}{arXiv:hep-th/0105155}) \item D. Cremades, [[Luis Ibáñez]], [[Fernando Marchesano]], \emph{Intersecting brane models of particle physics and the Higgs mechanism}, JHEP, 0207, 022 2002 (\href{https://arxiv.org/abs/hep-th/0203160}{arXiv:hep-th/0203160}) \item Arthur Hebecker, Alexander K. Knochel, [[Timo Weigand]], \emph{The Higgs mass from a String-Theoretic Perspective}, Nucl.Phys. B874 (2013) 1-35 (\href{https://arxiv.org/abs/1304.2767}{arXiv:1304.2767}) \item Manami Noumi Hashi, Hiroshi Isono, Toshifumi Noumi, Gary Shiu, Pablo Soler, \emph{Higgs Mechanism in Nonlocal Field Theories}, JHEP08 (2018) 064 (\href{https://arxiv.org/abs/1805.02676}{arXiv:1805.02676}) \end{itemize} See also \begin{itemize}% \item G. Aldazabal, S. Franco, [[Luis Ibáñez]], R. Rabadan, A. M. Uranga, \emph{$D=4$ Chiral String Compactifications from Intersecting Branes}, J.Math.Phys.42:3103-3126, 2001 (\href{https://arxiv.org/abs/hep-th/0011073}{arXiv:hep-th/0011073}) \item [[Ralph Blumenhagen]], [[Volker Braun]], Boris Kors, [[Dieter Lüst]], \emph{The Standard Model on the Quintic}, Summary of Talks at SUSY02, 1st Intl. Conference on String Phenomenology in Oxford, Strings 2002 and 35th Ahrenshoop Symposium. (\href{http://arxiv.org/abs/hep-th/0210083}{arXiv:hep-th/0210083}) \item [[Dieter Lüst]], \emph{Intersecting Brane Worlds -- A Path to the Standard Model?}, Class. Quant. Grav.21 : S1399-1424, 2004 (\href{http://arxiv.org/abs/hep-th/0401156}{arXiv:hep-th/0401156}) \item Ching-Ming Chen, Tianjun Li, Dimitri V. Nanopoulos, \emph{Standard-Like Model Building on Type II Orientifolds}, Nucl.Phys.B732:224-242,2006 (\href{http://arxiv.org/abs/hep-th/0509059}{arXiv:hep-th/0509059}) \item [[Angel Uranga]], \emph{The standard model from D-branes in string theory}, talk at Padova, January 2008 (\href{http://active.pd.infn.it/g4/seminars/2008/files/uranga.pdf}{pdf}) \item Matthew J. Dolan, Sven Krippendorf, Fernando Quevedo, \emph{Towards a Systematic Construction of Realistic D-brane Models on a del Pezzo Singularity}, JHEP 1110 (2011) 024 (\href{http://arxiv.org/abs/1106.6039}{arXiv:1106.6039}) \item Yuta Hamada, Tatsuo Kobayashi, Shohei Uemura, \emph{Standard Model-like D-brane models and gauge couplings}, Nuclear Physics B Volume 897, August 2015, Pages 563-582 (\href{https://arxiv.org/abs/1409.2740}{arXiv:1409.2740}) \item Jill Ecker, [[Gabriele Honecker]], Wieland Staessens, \emph{D6-Brane Model Building on $\mathbb{Z}_2 \times \mathbb{Z}_6$: MSSM-like and Left-Right Symmetric Models}, Nuclear Physics B Volume 901, December 2015, Pages 139-215, (\href{https://arxiv.org/abs/1509.00048}{arXiv:1509.00048}) \end{itemize} Intersection with [[O8-planes]]/[[D8-branes]] ([[M-theory on S1/G\_HW times H/G\_ADE]]) is discussed in \begin{itemize}% \item [[Amihay Hanany]], [[Alberto Zaffaroni]], \emph{Branes and Six Dimensional Supersymmetric Theories}, Nucl.Phys. B529 (1998) 180-206 (\href{https://arxiv.org/abs/hep-th/9712145}{arXiv:hep-th/9712145}) \item [[Amihay Hanany]], [[Alberto Zaffaroni]], \emph{Monopoles in String Theory}, JHEP 9912 (1999) 014 (\href{https://arxiv.org/abs/hep-th/9911113}{arXiv:hep-th/9911113}) \item E. Gorbatov, V.S. Kaplunovsky, J. Sonnenschein, [[Stefan Theisen]], S. Yankielowicz, \emph{On Heterotic Orbifolds, M Theory and Type I' Brane Engineering}, JHEP 0205:015, 2002 (\href{https://arxiv.org/abs/hep-th/0108135}{arXiv:hep-th/0108135}) \item Hirotaka Hayashi, Sung-Soo Kim, Kimyeong Lee, Futoshi Yagi, \emph{6d SCFTs, 5d Dualities and Tao Web Diagrams} (\href{https://arxiv.org/abs/1509.03300}{arXiv:1509.03300}) \end{itemize} \hypertarget{the_landscape_of_models}{}\subsubsection*{{The landscape of models}}\label{the_landscape_of_models} On the [[landscape of string theory vacua|landscape]] of intersecting D-brane models: Computer scan of [[Gepner model]]-[[KK-compactifications]] of intersecting D-brane models: \begin{itemize}% \item T.P.T. Dijkstra, L. R. Huiszoon, [[Bert Schellekens]], \emph{Chiral Supersymmetric Standard Model Spectra from Orientifolds of Gepner Models}, Phys.Lett. B609 (2005) 408-417 (\href{https://arxiv.org/abs/hep-th/0403196}{arXiv:hep-th/0403196}) \item T.P.T. Dijkstra, L. R. Huiszoon, [[Bert Schellekens]], \emph{Supersymmetric Standard Model Spectra from RCFT orientifolds}, Nucl.Phys.B710:3-57,2005 (\href{https://arxiv.org/abs/hep-th/0411129}{arXiv:hep-th/0411129}) \end{itemize} Computer scan of [[toroidal orbifold]]-[[KK compactifications]] is discussed in \begin{itemize}% \item [[Ralph Blumenhagen]], [[Florian Gmeiner]], [[Gabriele Honecker]], [[Dieter Lüst]], [[Timo Weigand]], \emph{The Statistics of Supersymmetric D-brane Models}, Nucl.Phys.B713:83-135, 2005 (\href{https://arxiv.org/abs/hep-th/0411173}{arXiv:hep-th/0411173}) \item [[Florian Gmeiner]], [[Ralph Blumenhagen]], [[Gabriele Honecker]], [[Dieter Lüst]], [[Timo Weigand]], \emph{One in a Billion: MSSM-like D-Brane Statistics}, JHEP 0601:004, 2006 (\href{https://arxiv.org/abs/hep-th/0510170}{arXiv:hep-th/0510170}) \end{itemize} \hypertarget{ReferencesDetailedRealisticModels}{}\subsubsection*{{Detailed realistic models}}\label{ReferencesDetailedRealisticModels} Realistic [[Yukawa couplings]] and [[fermion]] [[masses]] in an [[MSSM]] [[Pati-Salam GUT model]] with 3 [[generations of fermions]] realized on [[intersecting D-brane model|intersecting]] [[D6-branes]] [[KK-compactification|KK-compactified]] on a [[toroidal orbifold]] $T^6\sslash (\mathbb{Z}_2 \times \mathbb{Z}_2)$ are claimed in \begin{itemize}% \item Ching-Ming Chen, Tianjun Li, [[Van Eric Mayes]], [[Dimitri Nanopoulos]], \emph{A Realistic World from Intersecting D6-Branes}, Phys.Lett.B665:267-270, 2008 (\href{https://arxiv.org/abs/hep-th/0703280}{arXiv:hep-th/0703280}, \href{https://doi.org/10.1016/j.physletb.2008.06.024}{doi:10.1016/j.physletb.2008.06.024}) \item Ching-Ming Chen, Tianjun Li, [[Van Eric Mayes]], [[Dimitri Nanopoulos]], \emph{Realistic Yukawa Textures and SUSY Spectra from Intersecting Branes}, Phys.Rev.D77:125023, 2008 (\href{https://arxiv.org/abs/0711.0396}{arXiv:0711.0396}) \item [[Van Eric Mayes]], \emph{All Fermion Masses and Mixings in an Intersecting D-brane World} (\href{https://arxiv.org/abs/1902.00983}{arXiv:1902.00983}) \item Jordan Gemmill, Evan Howington, [[Van Eric Mayes]], \emph{One String to Rule Them All: Neutrino Masses and Mixing Angles} (\href{https://arxiv.org/abs/1907.07106}{arXiv:1907.07106}) \item Tianjun Li, Adeel Mansha, Rui Sun, \emph{Revisiting the Supersymmetric Pati-Salam Models from Intersecting D6-branes} (\href{https://arxiv.org/abs/1910.04530}{arXiv:1910.04530}) \end{itemize} \hypertarget{ReferencesLiftToMTheory}{}\subsubsection*{{Lift to M-theory}}\label{ReferencesLiftToMTheory} Lift of intersecting D-brane models to [[M-theory on G2-manifolds]] with [[ADE-singularities]] is discussed in the following articles \begin{itemize}% \item Per Berglund, Andreas Brandhuber, \emph{Matter from $G_2$-manifolds}, Nucl.Phys. B641 (2002) 351-375 (\href{https://arxiv.org/abs/hep-th/0205184}{arXiv:hep-th/0205184}) \item K. Behrndt, [[Gianguido Dall'Agata]], [[Dieter Lüst]], S. Mahapatra, \emph{Intersecting 6-branes from new 7-manifolds with G}2 holonomy\_, JHEP 0208:027,2002 (\href{https://arxiv.org/abs/hep-th/0207117}{arXiv:hep-th/0207117}) \item \hyperlink{BCLS05}{BCLS 05, section 2.9} \item Jacob L. Bourjaily, Sam Espahbodi, \emph{Geometrically Engineerable Chiral Matter in M-Theory} (\href{https://arxiv.org/abs/0804.1132}{arXiv:0804.1132}) \end{itemize} \hypertarget{ReferencesCosmology}{}\subsubsection*{{Cosmology}}\label{ReferencesCosmology} Discussion for [[cosmology]] of [[intersecting D-brane models]] (ambient $\sim$ [[anti de Sitter spacetimes]] with the $\sim$ conformal intersecting branes at the [[asymptotic boundary]]) includes the following (see also at \emph{[[Randall-Sundrum model]]}): \begin{itemize}% \item [[Igor Klebanov]], [[Matthew Strassler]], \emph{Supergravity and a Confining Gauge Theory: Duality Cascades and $\chi^{SB}$-Resolution of Naked Singularities}, JHEP 0008:052, 2000 (\href{https://arxiv.org/abs/hep-th/0007191}{arXiv:hep-th/0007191}) \item [[Igor Klebanov]], [[Edward Witten]], \emph{Superconformal Field Theory on Threebranes at a Calabi-Yau Singularity}, Nucl.Phys.B536:199-218, 1998 (\href{https://arxiv.org/abs/hep-th/9807080}{arXiv:hep-th/9807080}) \item Luis Anchordoqui, Jose Edelstein, Carlos Nunez, Santiago Perez Bergliaffa, Martin Schvellinger, Marta Trobo, Fabio Zyserman, \emph{Brane Worlds, String Cosmology, and AdS/CFT}, Phys. Rev. D64:084027, 2001 (\href{https://arxiv.org/abs/hep-th/0106127}{arXiv:hep-th/0106127}) \item Nemanja Kaloper, \emph{Origami World}, JHEP 0405 (2004) 061 (\href{https://arxiv.org/abs/hep-th/0403208}{arXiv:hep-th/0403208}) \item [[Angel Uranga]], section 18 of \emph{TASI lectures on String Compactification, Model Building, and Fluxes}, 2005 (\href{http://cds.cern.ch/record/933469/files/cer-002601054.pdf}{pdf}, \href{http:cds.cern.ch/record/933469}{cern:933469}) \item Antonino Flachi, Masato Minamitsuji, \emph{Field localization on a brane intersection in anti-de Sitter spacetime}, Phys.Rev.D79:104021, 2009 (\href{https://arxiv.org/abs/0903.0133}{arXiv:0903.0133}) \item Jiro Soda, \emph{AdS/CFT on the brane}, Lect.Notes Phys.828:235-270, 2011 (\href{https://arxiv.org/abs/1001.1011}{arXiv:1001.1011}) \item Gianluca Grignani, Troels Harmark, Andrea Marini, Marta Orselli, \emph{The Born-Infeld/Gravity Correspondence}, Phys. Rev. D 94, 066009 (2016) (\href{https://arxiv.org/abs/1602.01640}{arXiv:1602.01640}) \end{itemize} Survey is in \begin{itemize}% \item Antonio Padilla, \emph{Braneworld Cosmology and Holography} (\href{https://arxiv.org/abs/hep-th/0210217}{arxiv:hep-th/0210217}) \item Shunsuke Teraguchi, around slide 21 of: \emph{String theory and its relation to particle physics}, 2007 (\href{http://phys.cts.ntu.edu.tw/ppp7/talks/PPP7_Shunsuke_Teraguchi.pdf}{pdf}) \end{itemize} Discussion of 4d [[de Sitter spacetime]] [[cosmology]] models on brane worlds in $\sim$ [[anti de Sitter spacetime|AdS]] [[bulk]] spacetimes: \begin{itemize}% \item Souvik Banerjee, [[Ulf Danielsson]], Giuseppe Dibitetto, Suvendu Giri, Marjorie Schillo, \emph{Emergent de Sitter cosmology from decaying AdS} (\href{https://arxiv.org/abs/1807.01570}{arXiv:1807.01570}) \item Souvik Banerjee, [[Ulf Danielsson]], Giuseppe Dibitetto, Suvendu Giri, Marjorie Schillo, \emph{de Sitter Cosmology on an expanding bubble} (\href{https://arxiv.org/abs/1907.04268}{arXiv:1907.04268}) \end{itemize} \hypertarget{experimental_tests}{}\subsubsection*{{Experimental tests}}\label{experimental_tests} Discussion of observational/[[experiment|experimental]] test of brane world models: by analysis of the [[event horizon]] of the [[black hole]] in the center of the [[galaxy]] [[Messier 87]]: \begin{itemize}% \item Indrani Banerjee, Sumanta Chakraborty, Soumitra SenGupta, \emph{Silhouette of M87${}^*$: A new window to peek into the world of hidden dimensions} (\href{https://arxiv.org/abs/1909.09385}{arXiv:1909.09385}) \end{itemize} [[!redirects intersecting D-brane models]] [[!redirects intersecting D-brane model building]] [[!redirects branes at angles]] [[!redirects brane world model]] [[!redirects brane world models]] \end{document}