arXiv subjects

Adi Armoni

Publications and source records attributed to Adi Armoni.

At least 19 recordsLinked to original sources

arXiv2026

Domain Walls in Large-$N$ QCD$_3$

Large-$N$ three dimensional QCD with a level $k$ Chern-Simons term and $N_f$ massless flavours admits $N_f+1$ degenerate vacua. We discuss various aspects of the domain walls that interpolate between those vacua. Using a bosonic dual for the case $k \ge N_f/2$ we write down the profile of the composite wall. By fluctuating the profile, we find the 2d field theory that lives on the wall, a level-$N$ gauged WZW model, and compare it with a theory that was previously obtained by using anomaly inflow considerations. We also discuss the case $k < N_f/2$. Finally, we remark on the realisation of the wall as a D-brane in a holographic dual.

hep-th↗

arXiv2025

High-Energy Pion Scattering in Holographic QCD: A Comparison with Experimental Data

Following Polchinski and Strassler [1] and our previous work [2], we study high-energy pion scattering in the holographic QCD hard-wall model. In particular, we focus on comparing our predictions for the angular dependence of $\pi^{+} \pi^{-} \to \pi^{+} \pi^{-}$ scattering with experimental data extracted from the process $\pi^{-} p \to \pi^{+} \pi^{-} n$. Having previously shown that our approach reproduces the constituent counting rule found in QCD, we now observe qualitative agreement between our predictions and the extracted data in the high-energy fixed-angle regime. We also provide predictions for all other 2-to-2 pion scattering processes. Our approach can be extended to a broader range of meson and glueball scattering processes in various holographic QCD models.

hep-ph↗

arXiv2025

A Master Superspace Action for 3D S-Duality

We formulate a `master' partition function in three-dimensional $\mathcal{N}=2$ superspace that realises, upon integrating out complementary superfields, both the electric Maxwell--Chern--Simons (MCS) theory and its magnetic $S$-dual: a non-gauge Deser--Jackiw self-dual massive vector times a decoupled level-$k$ Chern--Simons term. The two descriptions share the topological mass $M=\frac{g^{2}k}{2\pi}$ and obey an exact partition-function identity $\mathcal Z_{\rm mag}(g_m^2,k)=\mathcal Z_{\rm ele}(g_e^2,k)$ with $g_e g_m=2\pi$, mapping a weakly coupled MCS theory to a strongly coupled Deser--Jackiw CS theory. Special limits reproduce pure Chern--Simons/Gaiotto--Witten ($g^{2}=0$) and Maxwell/compact-scalar duality ($k=0$). We extend the construction to a non-Abelian U$(N)$ gauge group obtaining $\mathcal N=2$ Yang--Mills--Chern--Simons on the electric side and a massive non-gauge vector coupled to level-$k$ Chern--Simons on the magnetic side; the interaction terms between the massive vector and the Chern-Simons term vanish in the Abelian case. Decomposing the $\mathcal N=2$ vector into an $\mathcal N=1$ vector and a real-linear multiplet factorises the master action and yields the $\mathcal N=1$ counterparts. This uplifts the bosonic duality formulated recently to $\mathcal N=2$ and clarifies its non-Abelian and $\mathcal N=1$ reductions.

hep-th↗

arXiv2024

High-Energy Fixed-Angle Meson Scattering and the Constituent Counting Rule in Holographic QCD

We investigate the high-energy fixed-angle scattering of pions and $\rho$-mesons in a bottom-up holographic QCD model. To this end, we generalise the approach of Polchinski and Strassler arXiv:hep-th/0109174 to write an ansatz for meson scattering amplitudes based on superstring scattering amplitudes in asymptotically AdS space. We demonstrate that our generalisation of the Polchinski--Strassler proposal is necessary to describe $\rho$-meson scattering consistently with the Nambu--Goldstone boson equivalence theorem. Our results for pion and $\rho$-meson scattering amplitudes are in agreement with the constituent counting rule found in QCD. Moreover, our proposal for 2-to-2 scattering amplitudes provides a method for computing scattering angle dependence.

hep-th↗

arXiv2024

A Note on Seiberg Duality for $N_{f} < N_{c}$

We consider SQCD for $N_{f}<N_{c}$. We use a brane configuration in type IIA string theory to propose a Seiberg dual. The brane configuration that realises the magnetic theory contains $N_{f}$ branes and $N_{c}-N_{f}$ \textit{anti}-branes, leading to an $SU(N_{c}-N_{f})$ gauge theory with $N_{f}$ flavours. The potential between the branes triggers a RG flow and we argue that the IR theory realises the Affleck-Dine-Seiberg superpotential. We use both field theory arguments, in particular anomaly matching, and a lift of the type IIA brane configuration to M-theory, in order to support our proposal.

hep-th↗

arXiv2023

Dualities of 3D $\mathcal{N}=1$ SQCD from Branes and non-SUSY deformations

We study the dynamics of an 'electric' $\mathcal{N}=1$ 3D $U(N_c)_{k,k+\frac{N_c}{2}}$ SQCD theory. By embedding the theory in string theory, we propose that the theory admits a 'magnetic' dual and analyse the low energy dynamics of the theory using its dual. When $\frac{N_f}{2} \ge\frac{N_c}{2}-k$ the IR dynamics is described by either a TQFT for large quark masses, or a Grassmanian and a Wess-Zumino (WZ) term for small masses. We also consider non-supersymmetric mass deformations and RG flows in the vicinity of the SUSY point and find agreement between the IR of the electric and its magnetic dual. When $\frac{N_f}{2} < \frac{N_c}{2}-k$ supersymmetry is broken and the IR dynamics is a described by a TQFT accompanied by a Goldstino. We also discuss SQCD theories based on $SO$/$USp$ gauge groups.

hep-th↗

arXiv2023

S-Dual of Maxwell Chern-Simons Theory

We discuss the dynamics of three dimensional Maxwell theory coupled to a level $k$ Chern-Simons term. Motivated by S-duality in string theory we argue that the theory admits an S-dual description. The S-dual theory contains a non-gauge 1-form field, previously proposed by Deser and Jackiw and a level $k$ $U(1)$ Chern-Simons term, $Z_{\rm MCS}=Z_{\rm DJ}Z_{\rm CS}$. The couplings to external electric and magnetic currents and their string theory realisations are also discussed.

hep-th↗

arXiv2022

Dualities of Adjoint QCD$_3$ from Branes

We consider an 'electric' $U(N)$ level $k$ QCD$_3$ theory with one adjoint Majorana fermion. Inspired by brane dynamics, we suggest that for $k \ge N/2$ the massive $m<0$ theory, in the vicinity of the supersymmetric point, admits a $U(k-\frac{N}{2})_{-(\frac{1}{2}k+\frac{3}{4}N),-(k+\frac{N}{2})}$ 'magnetic' dual with one adjoint Majorana fermion. The magnetic theory flows in the IR to a topological $U(k-\frac{N}{2})_{-N,-(k+\frac{N}{2})}$ pure Chern-Simons theory in agreement with the dynamics of the electric theory. When $k<N/2$ the magnetic dual is $U(\frac{N}{2}-k)_{\frac{1}{2}k+\frac{3}{4}N,N}$ with one adjoint Majorana fermion. Depending on the sign of the fermion mass, the magnetic theory flows to either $U(\frac{N}{2}-k)_{N,N}$ or $U(\frac{N}{2}-k)_{\frac{1}{2}N+k,N}$ TQFT. A second magnetic theory, $U(N/2+k)_{\frac{1}{2}k-\frac{3}{4}N,-N}$, flows to either $U(\frac{N}{2}+k)_{-N,-N}$ or $U(\frac{N}{2}+k)_{-(\frac{1}{2}N-k),-N}$ TQFT. Dualities for $SO$ and $USp$ theories with one adjoint fermion are also discussed.

hep-th↗

arXiv2022

GMOR relation for a QCD-like theory from S-duality

Following [1] we study a QCD-like gauge theory using a non-supersymmetric setup in type IIB string theory. The setup includes an $O3$ plane and $N$ D3 anti-branes and it realises a $USp(2N)$ 'electric' gauge theory with four "quarks" in the two-index antisymmetric representation and six heavy scalars in the adjoint representation. Using S-duality we obtain a dual 'magnetic' theory that includes $SO(2N-1)$ gauge theory theory with six scalars in the adjoint representation and four heavy "quarks" in the two-index symmetric representation. The dual theory provides a description of confinement and dynamical symmetry breaking of the form $SU(4)\rightarrow SO(4)$. We extend the results of [1] by adding masses to the quarks in the electric side and deriving parts of the chiral Lagrangian using the dual magnetic theory. In particular, we derive the Gell-Mann-Oakes-Renner (GMOR) relation for Nambu-Goldstone bosons (pions) using the magnetic theory.

hep-th↗

arXiv2020

Vacuum structure of large $N$ QCD$_3$ from holography

We study the vacuum structure of three-dimensional $SU(N)$ gauge theory coupled to a Chern-Simons term at level $k$ and to $F$ fundamental Dirac fermions. We use a large $N$ holographic description based on a D3/D7 system in type IIB string theory compactified on a supersymmetry breaking circle. The multiple vacua of the theory and the transitions between them are nicely captured by the dual holographic background. The resulting phase diagram, which we derive both at leading and first subleading orders in the $1/N$ expansion, shows a rich structure where topological field theories, non-linear sigma models and first-order phase transitions appear.

hep-th↗

arXiv2019

Metastable Vacua in Large-$N$ QCD$_3$

We reexamine the vacuum structure of three-dimensional quantum chromodynamics (QCD$_3$) with gauge group $SU(N)$, $N_f$ fundamental quark flavors, and a level-$k$ Chern-Simons term. This analysis can be reliably carried out in the large-$N$, fixed $N_f, k$ limit of the theory, up to certain assumptions that we spell out explicitly. At leading order in the large-$N$ expansion we find $N_f + 1$ distinct, exactly degenerate vacuum superselection sectors with different patterns of flavor-symmetry breaking. The associated massless Nambu-Goldstone bosons are generically accompanied by topological Chern-Simons theories. This set of vacua contains many candidate phases previously proposed for QCD$_3$. At subleading order in the large-$N$ expansion, the exact degeneracy between the different superselection sectors is lifted, leading to a multitude of metastable vacua. If we dial the quark masses, different metastable vacua can become the true vacuum of the theory, leading to a sequence of first-order phase transitions. This intricate large-$N$ dynamics can be captured by the previously proposed bosonic dual theories for QCD$_3$, provided these bosonic duals are furnished with a suitable scalar potential. Interestingly, this potential must include terms beyond quartic order in the scalar fields.

hep-th↗

arXiv2019

Phases of $\mathbf{U(N_c)}$ QCD$_3$ from Type 0 Strings and Seiberg Duality

We propose an embedding of $U(N_c)$ QCD$_3$ with a Chern-Simons term in string theory. The UV gauge theory lives on the worldvolume of a Hanany-Witten brane configuration in type 0B string theory in the presence of Sagnotti's O$'3$ orientifold. We use the brane configuration to propose a magnetic Seiberg dual. We identify various phases of the magnetic theory with conjectured phases of QCD$_3$. In particular the symmetry breaking and bosonization phases are both associated with condensation of the dual squark field. We also discuss the abelian theory without Chern-Simons term and argue that flavour symmetry is not broken. Finally, we also predict novel type 0B string dynamics from QCD dynamics.

hep-th↗

arXiv2019

Vacuum Structure of Charge k Two-Dimensional QED and Dynamics of an Anti D-String Near an O1- plane

We study the vacuum structure of N_f flavour two-dimensional QED with an arbitrary integer charge k. We find that the axial symmetry is spontaneously broken from Z_(kN_f) to Z_(N_f) due to the non-vanishing condensate of a flavour singlet operator, resulting in k degenerate vacua. An explicit construction of the k vacua is given by using a non-commutative algebra obtained as a central extension of the Z_(kN_f) discrete axial symmetry and Z_k 1-form (center) symmetry, which represents the mixed 't Hooft anomaly between them. We then give a string theory realization of such a system with k=2 and N_f=8 by putting an anti D-string in the vicinity of an orientifold O1- plane and study its dynamics using the two-dimensional gauge theory realized on it. We calculate the potential between the anti D-string and the O1- plane and find repulsion in both weak and strong coupling regimes of the two dimensional gauge theory, corresponding to long and short distances, respectively. We also calculate the potential for the (Q,-1) string (the bound state of an anti D-string and Q fundamental strings) located close to the O1- plane. The result is non-perturbative in the string coupling.

hep-th↗

arXiv2018

QCD3 with Two-Index Quarks, Mirror Symmetry and Fivebrane anti-BIons near Orientifolds

We consider a non-supersymmetric Hanany-Witten type IIB brane configuration that realises a three dimensional USp(2N) gauge theory with quarks in the two-index antisymmetric representation and SO(4) flavour symmetry. Using type IIB S-duality we find the mirror dual, an SO(2N-1) field theory with scalars in the antisymmetric representation. Analysing the magnetic dual we study the vacuum structure of the USp(2N) model and propose that the SO(4) global symmetry is unbroken. In order to support our proposal we present an SO(4) symmetric BIon configuration that describes anti-D3 branes polarising into fivebranes in the S-dual Hanany-Witten setup. We also comment on dynamical flavour symmetry breaking in other QCD3 theories with quarks in two-index representations.

hep-th↗

arXiv2017

Phases of QCD$_3$ from Non-SUSY Seiberg Duality and Brane Dynamics

We consider a non-supersymmetric USp Yang-Mills Chern-Simons gauge theory coupled to fundamental flavours. The theory is realised in type IIB string theory via an embedding in a Hanany-Witten brane configuration which includes an orientifold and anti-branes. We argue that the theory admits a magnetic Seiberg dual. Using the magnetic dual we identify dynamics in field theory and brane physics that correspond to various phases, obtaining a better understanding of 3d bosonization and dynamical breaking of flavour symmetry in USp QCD$_3$ theory. In field theory both phases correspond to magnetic 'squark' condensation. In string theory they correspond to open string tachyon condensation and brane reconnection. We also discuss other phases where the magnetic 'squark' is massive. Finally, we briefly comment on the case of unitary gauge groups.

hep-th↗

arXiv2017

Equivalence of Meson Scattering Amplitudes in Strong Coupling Lattice and Flat Space String Theory

We consider meson scattering in the framework of the lattice strong coupling expansion. In particular we derive an expression for the 4-point function of meson operators in the planar limit of scalar Chromodynamics. Interestingly, in the naive continuum limit the expression coincides with an independently known result, that of the worldline formalism. Moreover, it was argued by Makeenko and Olesen that (assuming confinement) the resulting scattering amplitude in momentum space is the celebrated expression proposed by Veneziano several decades ago. This motivates us to also use holography in order to argue that the continuum expression for the scattering amplitude is related to the result obtained from flat space string theory. Our results hint that at strong coupling and large-$N_c$ the naive continuum limit of the lattice formalism can be related to a flat space string theory.

hep-lat↗

arXiv2017

Holographic Corrections to the Veneziano Amplitude

We propose a holographic computation of the $2\rightarrow 2$ meson scattering in a curved string background, dual to a QCD-like theory. We recover the Veneziano amplitude and compute a perturbative correction due to the background curvature. The result implies a small deviation from a linear trajectory, which is a requirement of the UV regime of QCD.

hep-th↗

arXiv2017

Holographic Corrections to Meson Scattering Amplitudes

We compute meson scattering amplitudes using the holographic duality between confining gauge theories and string theory, in order to consider holographic corrections to the Veneziano amplitude and associated higher-point functions. The generic nature of such computations is explained, thanks to the well-understood nature of confining string backgrounds, and two different examples of the calculation in given backgrounds are used to illustrate the details. The effect we discover, whilst only qualitative, is re-obtainable in many such examples, in four-point but also higher point amplitudes.

hep-th↗