Holographic Schwinger effect with a moving D3-brane

We study the Schwinger effect with a moving D3-brane in a $\mathcal{N}$=4 SYM plasma with the aid of AdS/CFT correspondence. We discuss the test particle pair moving transverse and parallel to the plasma wind respectively. It is found that for both cases the presence of velocity tends to increase the Schwinger effect. In addition, the velocity has a stronger influence on the Schwinger effect when the pair moves transverse to the plasma wind rather than parallel.Comment: 8 pages, 6 figure

Holographic Schwinger effect in a confining D3-brane background with chemical potential

Using the AdS/CFT correspondence, we investigate the Schwinger effect in a confining D3-brane background with chemical potential. The potential between a test particle pair on the D3-brane in an external electric field is obtained. The critical field $E_c$ in this case is calculated. Also, we apply numerical method to evaluate the production rate for various cases. The results imply that the presence of chemical potential tends to suppress the pair production effect.Comment: 7 pages, 4 figure

Entropic destruction of heavy quarkonium from a deformed AdS5AdS_5 model

In this paper, we study the destruction of heavy quarkonium due to the entropic force in a deformed $AdS_5$ model. The effects of the deformation parameter on the inter-distance and the entropic force are investigated. The influence of the deformation parameter on the quarkonium dissociation is analyzed. It is shown that the inter-distance increases in the presence of the deformation parameter. In addition, the deformation parameter has the effect of decreasing the entropic force. This results imply that the quarkonium dissociates harder in a deformed AdS background than that in an usual AdS background, in agreement with earlier findings.Comment: 6 pages, 2 figures. Accepted by Advances in High Energy Physic

Superconducting proximity effect to the block antiferromagnetism in Ky_{y}Fe2−x_{2-x}Se2_{2}

Recent discovery of superconducting (SC) ternary iron selenides has block antiferromagentic (AFM) long range order. Many experiments show possible mesoscopic phase separation of the superconductivity and antiferromagnetism, while the neutron experiment reveals a sizable suppression of magnetic moment due to the superconductivity indicating a possible phase coexistence. Here we propose that the observed suppression of the magnetic moment may be explained due to the proximity effect within a phase separation scenario. We use a two-orbital model to study the proximity effect on a layer of block AFM state induced by neighboring SC layers via an interlayer tunneling mechanism. We argue that the proximity effect in ternary Fe-selenides should be large because of the large interlayer coupling and weak electron correlation. The result of our mean field theory is compared with the neutron experiments semi-quantitatively. The suppression of the magnetic moment due to the SC proximity effect is found to be more pronounced in the d-wave superconductivity and may be enhanced by the frustrated structure of the block AFM state.Comment: 6 pages, 6 figure

Holographic imaginary potential of a quark antiquark pair in the presence of gluon condensation

For a moving heavy quark antiquark ($Q\bar Q$), in a quark gluon plasma (QGP), we use gauge/gravity duality to study both real and imaginary parts of the potential (ReV and ImV respectively) in a gluon condensate (GC) theory. The complex potential is derived from the Wilson loop by considering the thermal fluctuations of the worldsheet of the Nambu-Goto holographic string. We calculate in both cases where the axis of the moving $Q\bar Q$ pair is transverse and parallel with respect to its direction of movement in the plasma. For the ReV, we find that the inclusion of GC increases the dissociation length while rapidity has the opposite effect. For the ImV, we observe that increasing GC leads to a decrease in the onset of the ImV and thus decreases quarkonia dissociation, consistent with previous results on the entropic force. We also discuss the behavior of the thermal width of a moving $Q\bar Q$ with GC.Comment: 21 pages, 10 figures, references are adde