A new holographic model of chiral symmetry breaking

Abstract

A new holographic model of chiral symmetry breakingTo cite this article: Stanislav Kuperstein and Jacob Sonnenschein JHEP09 (2008) Abstract: A new family of models of flavour chiral symmetry breaking is proposed. The models are based on the embedding of a stack of D7 branes and a stack of anti-D7 branes in the conifold background. This family of gravity models is dual to a field theory with spontaneous breaking of conformal invariance and chiral flavour symmetry. We identify the corresponding Goldstone bosons and compute the spectra of massive scalar and vector mesons. The dual quiver gauge theory is also discussed. We further analyse a model where chiral symmetry is not broken.

Holographic bilayer/monolayer phase transitions

“…For a three dimensional field theory, the leading mode should behave as r ∆−3+p , while the subleading mode should asymptote to r −∆+p for some constant p. Using equation (3.5), one can easily check that the operator O ψ + ψ − has conformal dimension four. Using equations (3.6) and (3.7), one can verify that O ψ + ψ − ∝ 1/(∆z) 4 , which agrees with the operator O ψ + ψ − having engineering dimension four. Note that if we set r z = 0, the analogue of the U-shaped embedding is given by a pair of parallel D5/D5-branes positioned at z = ±…”

“…focus was on studying an r-dependent profile of the D5/D5-brane embedding in the internal space (thus corresponding to a monolayer phase) which geometrically realises spontaneous conformal [3] and chiral symmetry breaking via a U-shaped brane embedding similar to the Kuperstein-Sonnenschein D3/D7/D7 construction [4]. There is also the possibility of straight embeddings that fall into the horizon of the black hole once a non-zero temperature is turned on.…”

“…For the case at hand, the angle ψ has a zero classical value, while there is a profile for the x 3 coordinate. Contrary to the approach followed in [1] (and also in [4]), we will not introduce a new set of Cartesian coordinates in order to realize even and odd boundary conditions. Instead, this will be achieved by a convenient reparametrization of the relevant equations in their Schrödinger form.…”

Successes and failures of a more comprehensive hard wall AdS/QCD

“…See [7] for details. 5 We could extend the range of ∆ down to the unitarity bound ∆ > 1 by choosing ∆ to be the smaller of the two roots of ∆(∆ − 4) = m 2 X , which is permissible when −4 < m 2 X < −3.…”

“…Bottom-up models do not descend directly from string theory (as do the top-down setups of [4,5]), but rather posit the existence of a gravity dual for low-energy QCD, and study the dynamics of fields dual to QCD operators in a simple confining background. Though these frameworks are admittedly more ad hoc than top-down models, they remain essential tools for gaining a firmer grasp on the five-dimensional (5d) dual to QCD.…”