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41
Magnetic bion condensation: A new mechanism of confinement and mass gap in four dimensions, arXiv:0709.3269 [hepth
 26 A. Armoni, JHEP
, 2007
"... Abstract: In recent work, we derived the long distance confining dynamics of certain QCDlike gauge theories formulated on small S 1 × R 3 based on symmetries, an index theorem and abelian duality. Here, we give the microscopic derivation. The solution reveals a new mechanism of confinement in QCD(ad ..."
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Cited by 37 (4 self)
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Abstract: In recent work, we derived the long distance confining dynamics of certain QCDlike gauge theories formulated on small S 1 × R 3 based on symmetries, an index theorem and abelian duality. Here, we give the microscopic derivation. The solution reveals a new mechanism of confinement in QCD(adj) in the regime where we have control over both perturbative and nonperturbative aspects. In particular, consider SU(2) QCD(adj) theory with 1 ≤ nf ≤ 4 Majorana fermions, a theory which undergoes gauge symmetry breaking at small S 1. If the magnetic charge of the BPS monopole is normalized to unity, we show that confinement occurs due to condensation of objects with magnetic charge 2, not 1. Due to index theorems, we know that such an object cannot be a two identical monopole configuration. Its net topological charge must vanish, and hence it must be topologically indistinguishable from the perturbative vacuum. We construct such objects, the magnetically charged, topologically null molecules of a BPS monopole and KK antimonopole, which we refer as magnetic bions. An immediate puzzle with this proposal is the apparent Coulomb repulsion between BPSKK pair. An attraction which overcomes the Coulomb repulsion between the two is induced by 2nffermion exchange. Bion condensation is also the mechanism of confinement in N = 1 SYM on the same fourmanifold. The SU(N) generalization hints a possible hidden integrability behind nonsupersymmetric QCD of affine Toda type, and allows us to analytically compute the string tensions and thicknesses. We currently do not know the extension to R 4.
Analytic derivation of dual gluons and monopoles from SU(2) lattice YangMills theory  I. BF YangMills representation
, 2006
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Pinch Technique: Theory and Applications
, 2009
"... We review the theoretical foundations and the most important physical applications of the Pinch Technique (PT). This general method allows the construction of offshell Green’s functions in nonAbelian gauge theories that are independent of the gaugefixing parameter and satisfy ghostfree Ward iden ..."
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Cited by 5 (0 self)
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We review the theoretical foundations and the most important physical applications of the Pinch Technique (PT). This general method allows the construction of offshell Green’s functions in nonAbelian gauge theories that are independent of the gaugefixing parameter and satisfy ghostfree Ward identities. We first present the diagrammatic formulation of the technique in QCD, deriving at one loop the gauge independent gluon selfenergy, quarkgluon vertex, and threegluon vertex, together with their Abelian Ward identities. The generalization of the PT to theories with spontaneous symmetry breaking is carried out in detail, and the profound connection with the optical theorem and the dispersion relations are explained within the electroweak sector of the Standard Model. The equivalence between the PT and the Feynman gauge of the Background Field Method (BFM) is elaborated, and the crucial differences between the two methods are critically scrutinized. A variety of field theoretic techniques needed for the generalization of the PT to all orders are introduced, with particular emphasis on the BatalinVilkovisky quantization method and the general formalism of algebraic renormalization. The main conceptual and technical issues related to the extension of the technique beyond one loop are described, using the twoloop
Color dynamics in external fields
 JHEP
"... Abstract: We investigate the vacuum dynamics of U(1), SU(2), and SU(3) lattice gauge theories in presence of external (chromo)magnetic fields, both in (3+1) and (2+1) dimensions. We find that the critical coupling for the phase transition in compact U(1) gauge theory is independent of the strength o ..."
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Cited by 4 (3 self)
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Abstract: We investigate the vacuum dynamics of U(1), SU(2), and SU(3) lattice gauge theories in presence of external (chromo)magnetic fields, both in (3+1) and (2+1) dimensions. We find that the critical coupling for the phase transition in compact U(1) gauge theory is independent of the strength of an external magnetic field. On the other hand we find that, both in (3+1) and (2+1) dimensions, the deconfinement temperature for SU(2) and SU(3) gauge systems in a constant abelian chromomagnetic field decreases when the strength of the applied field increases. We conclude that the dependence of the deconfinement temperature on the strength of an external constant chromomagnetic field is a peculiar feature of non abelian gauge theories and could be useful to get insight into color confinement.
Nonperturbative match of ultraviolet renormalon
"... The paper is motivated by observation of a kind of branes in the vacuum state of the lattice SU(2) gluodynamics. The branes represent twodimensional vortices whose total area scales in physical units while the nonAbelian action diverges in the ultraviolet. We consider the question whether effects ..."
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Cited by 3 (2 self)
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The paper is motivated by observation of a kind of branes in the vacuum state of the lattice SU(2) gluodynamics. The branes represent twodimensional vortices whose total area scales in physical units while the nonAbelian action diverges in the ultraviolet. We consider the question whether effects of the branes can be accommodated into the continuum theory. We demonstrate that at least in case of the gluon condensate (plaquette action) and of the heavy quark potential the contribution of the branes corresponds to the ultraviolet renormalon. Thus, the vortices might represent a nonperturbative match of the ultraviolet renormalon. Such an identification constrains, in turn, properties of the branes. 1.
Persistent challenges of quantum chromodynamics, Lilienfeld Prize Lecture
 Int. J. Mod. Phys. A
"... Unlike some models whose relevance to Nature is still a big question mark, Quantum Chromodynamics will stay with us forever. Quantum Chromodynamics (QCD), born in 1973, is a very rich theory supposed to describe the widest range of strong interaction phenomena: from nuclear physics to Regge behavior ..."
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Unlike some models whose relevance to Nature is still a big question mark, Quantum Chromodynamics will stay with us forever. Quantum Chromodynamics (QCD), born in 1973, is a very rich theory supposed to describe the widest range of strong interaction phenomena: from nuclear physics to Regge behavior at large E, from color confinement to quarkgluon matter at high densities/temperatures (neutron stars); the vast horizons of the hadronic world: chiral dynamics, glueballs, exotics, light and heavy quarkonia and mixtures thereof, exclusive and inclusive phenomena, interplay between strong forces and weak interactions, etc. Efforts aimed at solving the underlying theory, QCD, continue. In a remarkable entanglement, theoretical constructions of the 1970s and 1990s combine with today’s ideas based on holographic description and strong–weak coupling duality, to provide new insights and a deeper understanding.
Soliton junctions in the large magnetic flux limit,” Nucl
 Phys.. B 754, 293 (2006) [arXiv:hepth/0606065]. – 25
"... We study the flux tube junctions in the limit of large magnetic flux. In this limit the flux tube becomes a wall vortex which is a wall of negligible thickness (compared to the radius of the tube) compactified on a cylinder and stabilized by the flux inside. This wall surface can also assume differe ..."
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Cited by 2 (2 self)
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We study the flux tube junctions in the limit of large magnetic flux. In this limit the flux tube becomes a wall vortex which is a wall of negligible thickness (compared to the radius of the tube) compactified on a cylinder and stabilized by the flux inside. This wall surface can also assume different shapes that correspond to soliton junctions. We can have a flux tube that ends on a wall, a flux tube that ends on a monopole and more generic configurations containing all three of them. In this paper we find the differential equations that describe the shape of the wall vortex surface for these junctions. We will restrict to the cases of cylindrical symmetry. We also solve numerically these differential equations for various kinds of junctions. We finally find an interesting relation between soliton junctions and dynamical systems.
PT Symmetry and QCD: Finite Temperature and Density
, 2009
"... The relevance of PT symmetry to quantum chromodynamics (QCD), the gauge theory of the strong interactions, is explored in the context of finite temperature and density. Two significant problems in QCD are studied: the sign problem of finitedensity QCD, and the problem of confinement. It is proven t ..."
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The relevance of PT symmetry to quantum chromodynamics (QCD), the gauge theory of the strong interactions, is explored in the context of finite temperature and density. Two significant problems in QCD are studied: the sign problem of finitedensity QCD, and the problem of confinement. It is proven that the effective action for heavy quarks at finite density is PTsymmetric. For the case of 1+1 dimensions, the PTsymmetric Hamiltonian, although not Hermitian, has real eigenvalues for a range of values of the chemical potential µ, solving the sign problem for this model. The effective action for heavy quarks is part of a potentially large class of generalized sineGordon models which are nonHermitian but are PTsymmetric. Generalized sineGordon models also occur naturally in gauge theories in which magnetic monopoles lead to confinement. We explore gauge theories where monopoles cause confinement at arbitrarily high temperatures. Several different classes of monopole gases exist, with each class leading to different string tension scaling laws. For one class of monopole gas models, the PTsymmetric affine Toda field theory emerges naturally as the effective theory. This in turn leads to sinelaw scaling for string tensions, a behavior consistent with lattice simulations.
Supervisors:
, 2012
"... ‘Äntligen hade korpen slagit ner på ett tak. “Ser du, att det är sant, ..."
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