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

2019 ◽  
Vol 79 (11) ◽  
Author(s):  
Wenhe Cai ◽  
Kang-le Li ◽  
Si-wen Li

Abstract Using the Witten–Sakai–Sugimoto model in the D0–D4 background, we holographically compute the vacuum decay rate of the Schwinger effect in this model. Our calculation contains the influence of the D0-brane density which could be identified as the $$\theta $$θ angle or chiral potential in QCD. Under the strong electromagnetic fields, the instability appears due to the creation of quark–antiquark pairs and the associated decay rate can be obtained by evaluating the imaginary part of the effective Euler–Heisenberg action which is identified as the action of the probe brane with a constant electromagnetic field. In the bubble D0–D4 configuration, we find the decay rate decreases when the $$\theta $$θ angle increases since the vacuum becomes heavier in the present of the glue condensate in this system. And the decay rate matches to the result in the black D0–D4 configuration at zero temperature limit according to our calculations. In this sense, the Hawking–Page transition of this model could be consistently interpreted as the confined/deconfined phase transition. Additionally there is another instability from the D0-brane itself in this system and we suggest that this instability reflects to the vacuum decay triggered by the $$\theta $$θ angle as it is known in the $$\theta $$θ-dependent QCD.

1999 ◽  
Vol 14 (23) ◽  
pp. 3715-3730 ◽  
Author(s):  
GABRIEL H. FLORES ◽  
N. F. SVAITER ◽  
RUDNEI O. RAMOS

We evaluate both the vacuum decay rate at zero temperature and the finite temperature nucleation rate for the [Formula: see text] model. Using the thin-wall approximation, we obtain the bounce solution for the model and we were also able to give the approximate eigenvalue equations for the bounce.


2006 ◽  
Vol 15 (08) ◽  
pp. 1761-1768 ◽  
Author(s):  
H. NAKADA ◽  
K. TANABE

To investigate the pairing phase transition in finite systems with the particle-number conservation, we formulate a new BCS-type theory at finite temperature, by deriving a set of variational equations of the free energy after the particle-number projection. This theory enables us to distinguish the symmetry-restoring fluctuation (SRF) from additional quantum fluctuations. By numerical calculations, it is found that the phase transition is compatible with the conservation law in this theory, and that the SRF shifts up the critical temperature. Having correct zero-temperature limit, this theory also gives new interpretation on the Pauli blocking effect in systems with odd particle number.


2021 ◽  
Vol 81 (9) ◽  
Author(s):  
Si-wen Li

AbstractUsing the gauge-gravity duality, we study the holographic Schwinger effect by performing the potential analysis on the confining D3- and D4-brane background with D-instantons then evaluate the pair production/decay rate by taking account into a fundamental string and a single flavor brane respectively. The two confining backgrounds with D-instantons are obtained from the black D(-1)–D3 and D0–D4 solution with a double Wick rotation. The total potential and pair production/decay rate in the Schwinger effect are calculated numerically by examining the NG action of a fundamental string and the DBI action of a single flavor brane all in the presence of an electric field. In both backgrounds our numerical calculation agrees with the critical electric field evaluated from the DBI action and shows the potential barrier is increased by the presence of the D-instantons, thus the production/decay rate is suppressed by the D-instantons. The interpretation is that particles in the dual field theory could acquire an effective mass through the Chern-Simons interaction or the theta term due to the presence of D-instantons so that the pair production/decay rate in Schwinger effect is suppressed since it behaves as $$e^{-m^{2}}$$ e - m 2 . This conclusion is in agreement with the previous results obtained in the deconfined D(-1)–D3 background at zero temperature limit and from the approach of the flavor brane in the D0–D4 background. In this sense, this work may be also remarkable to study the phase transition in Maxwell–Chern–Simons theory and observable effects by the theta angle in QCD.


2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Xiaofu Zhang ◽  
Adriana E. Lita ◽  
Huanlong Liu ◽  
Varun B. Verma ◽  
Qiang Zhou ◽  
...  

AbstractThe nature of the magnetic-field driven superconductor-to-insulator quantum-phase transition in two-dimensional systems at zero temperature has been under debate since the 1980s, and became even more controversial after the observation of a quantum-Griffiths singularity. Whether it is induced by quantum fluctuations of the superconducting phase and the localization of Cooper pairs, or is directly driven by depairing of these pairs, remains an open question. We herein experimentally demonstrate that in weakly-pinning systems and in the limit of infinitely wide films, a sequential superconductor-to-Bose insulator-to-Fermi insulator quantum-phase transition takes place. By limiting their size to smaller than the effective penetration depth, however, the vortex interaction alters, and the superconducting state re-enters the Bose-insulating state. As a consequence, one observes a direct superconductor-to-Fermi insulator in the zero-temperature limit. In narrow films, the associated critical-exponent products diverge along the corresponding phase boundaries with increasing magnetic field, which is a hallmark of the quantum-Griffiths singularity.


2007 ◽  
Vol 99 (26) ◽  
Author(s):  
P. M. Walmsley ◽  
A. I. Golov ◽  
H. E. Hall ◽  
A. A. Levchenko ◽  
W. F. Vinen

1988 ◽  
Vol 66 (4) ◽  
pp. 549-552 ◽  
Author(s):  
Jane E. Callanan ◽  
Ron D. Weir ◽  
Edgar F. Westrum Jr.

We have measured the heat capacity of the fast ion conductor PbSnF4 at 10.3 < T < 352 K by adiabatic calorimetry. Our results show anomalous values in the Cp,m in the region 300 < T < 352 K. These are associated with the α–β crystallographic transition reported at 353 K. Because the upper temperature limit of our cryostat is around 354 K, it was impossible to follow the phase transition to completion. A more subtle anomaly in the Cp,m was detected between 130 and 160 K. Standard molar thermodynamic functions are presented at selected temperatures from 5 to 350 K.


2018 ◽  
Vol 33 (25) ◽  
pp. 1850144
Author(s):  
Maryam Gholizadeh Arashti ◽  
Majid Dehghani

The Schwinger effect in the presence of instantons and background magnetic field was considered to study the dependence of critical electric field on instanton density and magnetic field using AdS/CFT conjecture. The gravity side is the near horizon limit of D3[Formula: see text]D(−[Formula: see text]1) background with electric and magnetic fields on the brane. Our approach is based on the potential analysis for particle–antiparticle pair at zero and finite temperatures, where the zero temperature case is a semi-confining theory. We find that presence of instantons suppresses the pair creation effect, similar to a background magnetic field. Then, the production rate will be obtained numerically using the expectation value of circular Wilson loop. The obtained production rate in a magnetic field is in agreement with previous results.


2018 ◽  
Vol 33 (03) ◽  
pp. 1850008
Author(s):  
Sen Hu ◽  
Guozhen Wu

We consider backreacted [Formula: see text] coupled with [Formula: see text] massive flavors introduced by D7 branes. The backreacted geometry is in the Veneziano limit with fixed [Formula: see text]. By dividing one of the directions into a line segment with length l, we get two subspaces. Then we calculate the entanglement entropy between them. With the method of [I. R. Klebanov, D. Kutasov and A. Murugan, Nucl. Phys. B 796, 274 (2008)], we are able to find the cut-off independent part of the entanglement entropy and finally find that this geometry shows no confinement/deconfinement phase transition at zero temperature from the holographic entanglement entropy point of view similar to the case in pure [Formula: see text].


2021 ◽  
Vol 119 (3) ◽  
pp. 033502
Author(s):  
Paul G. Baity ◽  
Dmytro A. Bozhko ◽  
Rair Macêdo ◽  
William Smith ◽  
Rory C. Holland ◽  
...  

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