Dynamically flavored description of holographic QCD in the presence of a magnetic field

Abstract

We construct the gravitational solution of the Witten-Sakai-Sugimoto model by introducing a magnetic field on the flavor brane. With taking into account their backreaction, we re-solve the type IIA supergravity in the presence of the magnetic field. Our calculation shows the gravitational solutions are magnetic-dependent and analytic both in the bubble (confined) and black brane (deconfined) case. We study the dual field theory at the leading order in the ratio of the number of flavors and colors, also in the Veneziano limit. Some physical properties related to the hadronic physics in an external magnetic field are discussed by using our confined backreaction solution holographically. We also investigate the thermodynamics and holographic renormalization of this model in both phases by our solution. Since the backreaction of the magnetic field is considered in our gravitational solution, it allows us to study the Hawking-Page transition with flavors and colors of this model in the presence of the magnetic field. Finally we therefore obtain the holographic phase diagram with the contributions from the flavors and the magnetic field. Our holographic phase diagram is in agreement with lattice QCD result qualitatively, which thus can be interpreted as the inhibition of confinement or chirally broken symmetry by the magnetic field. 1 the behavior of the Witten-Sakai-Sugimoto model interpolates between NJL and QCD according to [15,30,31,32,33].

Electromagnetic instability and Schwinger effect in the Witten–Sakai–Sugimoto model with D0–D4 background

“…Nevertheless, our result would be significant. Since the Hawking-Page transition in the WSS model is usually interpreted as confined/deconfined phase transition in QCD [31,35], it means the observables in the deconfined phase should return to confined case if the temperature goes to zero. So our results supports this statements qualitatively because it illustrates the creation rate obtained in the black D0-D4 background (at finite temperature) returns to the result from the bubble D0-D4 background (zero temperature).…”

“…The creation of quark-antiquark is proportional to log 1 T in [14,15] which diverges at zero temperature limit, while it is always finite in our D0-D4/D8 system or the original Witten-Sakai-Sugimoto model. However, this result is not surprised because there is a confining scale in the compactified D4-brane (with or without smeared D0-branes) system as (7) or (8), and on the other hand the bubble configuration would be thermodynamically dominated at low temperature while the black brane configuration arises at high temperature [31,33,34,35]. Consequently our calculation in the black D0-D4 configuration (high temperature) consistently coincides with the case in bubble D0-D4 (low temperature) at zero temperature limit, which means the creation rate should be definitely finite.…”

“…Therefore the number density of D0-branes (D0 charge) is related to the θ angle and we could finally obtain the Yang-Mills plus Chern-Simons action (1) from (2) and (3) as the low-energy theory of the bubble D0-D4 system. As the analysis of the D4/D8 model (the original Witten-Sakai-Sugimoto model) [31,32,33,34,35], the bubble D0-D4 corresponds to the confinement phase of the dual field theory while the black D0-D4 corresponds to the deconfinement phase 1 . However in the black D0-D4 configuration, the physical interpretation of D0-brane is less clear since D0-brane is not D-instanton.…”

Stochastic Motion of Heavy Quarks in Holography: A Theory-Independent Treatment

“…To this direction the gauge/gravity duality could also provide very insightful qualitative results. In this context, the flavor is added to the correspondence with the use of the Dp-branes, where the quenched limit is easier tractable [103,104], while the unquenched limit is demanding computationally [105,106], so approximate or numerical methods have been developed and the relevant screening on several observables has been observed, for example [107,108,109,110,111,112].…”

Heavy holographic QCD

“…This is borne out in its phase structure [8], which can be mapped to large-N c QCD predictions [9,10]. Approaching the realistic regime of small N c in a rigorous way is very difficult, although N f /N c corrections, where N f is the number of flavors, have been discussed [11,12]. A promising alternative is the so-called decompactified limit, where the gluon dynamics are decoupled.…”