DRDibakar Roychowdhury

Dibakar Roychowdhury

*This is an algorithmically generated author record based on publicly available information.

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Dibakar Roychowdhury has a total of 8 co-authors. Here are the top co-authors by number of shared publications:


Latest Publications

  • Open Access

    Holographic droplets in p-wave insulator/superconductor transition

    by Dibakar Roychowdhury

    In the present paper, based on the notion of marginally stable modes of vector perturbations in the AdS soliton back ground we investigate the magnetic field effect on holographic $ p $- wave insulator/superconductor transition in the probe limit. We perform explicit analytic calculations considering both Schwarzschild AdS soliton and Gauss Bonnet AdS soliton back grounds and obtain a unique relation between the chemical potential and the magnetic field near the critical point. We also extend our analysis for $ p+ip $- wave back ground in the presence of external magnetic field. In both the cases it is observed that the non abelian model exhibit \textit{droplet} solutions. Moreover it is also found that the increase in the value of the external magnetic field essentially reduces the size of the droplet and thereby makes the condensation harder.

  • Holographics-wave condensate with nonlinear electrodynamics: A nontrivial boundary value problem

    by Rabin Banerjee, Sunandan Gangopadhyay, Dibakar Roychowdhury, Arindam Lala

    In this paper, considering the probe limit, we analytically study the onset of holographic $s$-wave condensate in the planar Schwarzschild-AdS background. Inspired by various low-energy features of string theory, in the present work we replace the conventional Maxwell action with a (nonlinear) Born-Infeld action which essentially corresponds to the higher-derivative corrections of the gauge fields. Based on a variational method which is commonly known as the Sturm-Liouville eigenvalue problem and considering a nontrivial asymptotic solution for the scalar field, we compute the critical temperature for the $s$-wave condensation. The results thus obtained analytically agree well with the numerical findings [J. Jing and S. Chen, Phys. Lett. B 686, 68 (2010)]. As a next step, we extend our perturbative technique to compute the order parameter for the condensation. Interestingly, our analytic results are found to be of the same order as the numerical values obtained earlier.


  • Open Access

    Holographic s-wave condensate with non-linear electrodynamics: A nontrivial boundary value problem

    by Rabin Banerjee, Sunandan Gangopadhyay, Dibakar Roychowdhury, Arindam Lala

    In this paper, considering the probe limit, we analytically study the onset of holographic s-wave condensate in the planar Schwarzschild-AdS background. Inspired by various low energy features of string theory, in the present work we replace the conventional Maxwell action by a (non-linear) Born-Infeld (BI) action which essentially corresponds to the higher derivative corrections of the gauge fields. Based on a variational method, which is commonly known as the Sturm-Liouville (SL) eigenvalue problem and considering a non-trivial asymptotic solution for the scalar field, we compute the critical temperature for the s-wave condensation. The results thus obtained analytically agree well with the numerical findings\cite{hs19}. As a next step, we extend our perturbative technique to compute the order parameter for the condensation. Interestingly our analytic results are found to be of the same order as the numerical values obtained earlier.

  • Open Access

    Effect of external magnetic field on holographic superconductors in presence of nonlinear corrections

    by Dibakar Roychowdhury

    In this paper, based on analytic technique, several properties of holographic $ s $-wave superconductors have been investigated in the presence of various higher derivative (\textit{non linear}) corrections to the usual Maxwell action. Explicit expressions for the critical temperature and the condensation values have been obtained in the probe limit. Finally, the nature of condensate solutions have been investigated by immersing the superconductor in an external magnetic field. It is found that below certain critical magnetic field strength ($ B_c $) there exists a superconducting phase. Most importantly it has been observed that the value of this critical field strength ($ B_c $) indeed gets affected due to the presence of higher derivative corrections to the usual Maxwell action.

  • Open Access

    Phase transition and scaling behavior of topological charged black holes in Horava-Lifshitz gravity

    by Bibhas Ranjan Majhi, Dibakar Roychowdhury

    Gravity can be thought as an emergent phenomenon and it has a nice "thermodynamic" structure. In this context, it is then possible to study the thermodynamics without knowing the details of the underlying microscopic degrees of freedom. Here, based on the ordinary thermodynamics, we investigate the phase transition of the static, spherically symmetric charged black hole solution with arbitrary scalar curvature $2k$ in Ho\v{r}ava-Lifshitz gravity at the Lifshitz point $z=3$. The analysis is done using the canonical ensemble frame work; i.e. the charge is kept fixed. We find (a) for both $k=0$ and $k=1$, there is no phase transition, (b) while $k=-1$ case exhibits the second order phase transition within the {\it physical region} of the black hole. The critical point of second order phase transition is obtained by the divergence of the heat capacity at constant charge. Near the critical point, we find the various critical exponents. It is also observed that they satisfy the usual thermodynamic scaling laws.

  • Open Access

    AdS/CFT superconductors with Power Maxwell electrodynamics: reminiscent of the Meissner effect

    by Dibakar Roychowdhury

    Based on an analytic scheme and neglecting the back reaction effect several crucial properties of holographic $ s $- wave superconductors have been investigated in the presence of an external magnetic field in the background of a $ D $ dimensional Schwarzschild AdS space time. Inspired by low energy limit of heterotic string theory, in the present paper we replace the conventional Maxwell action by a Power Maxwell action. Immersing the holographic superconductors in an external static magnetic field the spatially dependent condensate solutions have been obtained analytically. Interestingly enough it is observed that condensation can form only below a certain critical field strength ($ B_c $). Finally, and most importantly it is observed that the value of this critical field strength increases as the mass of the scalar particles gets higher, which indicates the onset of a harder condensation.

  • Open Access

    Ehrenfest's scheme and thermodynamic geometry in Born-Infeld AdS black holes

    by Arindam Lala, Dibakar Roychowdhury

    In this paper we analyze the phase transition phenomena in Born-Infeld AdS black holes using Ehrenfest's scheme of standard thermodynamics. The critical points are marked by the divergences in the heat capacity. In order to investigate the nature of the phase transition, we analytically check both the Ehrenfest's equations near the critical points. Our analysis reveals that this is indeed a second order phase transition. Finally, we analyze the nature of the phase transition using state space geometry approach. This is found to be compatible with the Ehrenfest's scheme.

  • Ehrenfest’s scheme and thermodynamic geometry in Born-Infeld AdS black holes

    by Arindam Lala, Dibakar Roychowdhury

    In this paper, we analyze the phase transition phenomena in Born-Infeld anti-de Sitter (BI AdS) black holes using Ehrenfest's scheme of standard thermodynamics. The critical points are marked by the divergences in the heat capacity. In order to investigate the nature of the phase transition, we analytically check both Ehrenfest equations near the critical points. Our analysis reveals that this is indeed a second order phase transition. Finally, we analyze the nature of the phase transition using the state space geometry approach. This is found to be compatible with Ehrenfest's scheme.


  • Open Access

    A unified picture of phase transition: from liquid-vapour systems to AdS black holes

    by Rabin Banerjee, Sujoy Kumar Modak, Dibakar Roychowdhury

    Based on fundamental concepts of thermodynamics we examine phase transitions in black holes defined in Anti-de Sitter (AdS) spaces. The method is in line with that used a long ago to understand the liquid-vapour phase transition where the first order derivatives of Gibbs potential are discontinuous and Clausius-Clapeyron equation is satisfied. The idea here is to consider the AdS black holes as grand-canonical ensembles and study phase transition defined by the discontinuity of second order derivatives of Gibbs potential. We analytically check that this phase transition between the `smaller' and `larger' mass black holes obey Ehrenfest relations defined at the critical point and hence confirm a second order phase transition. This include both the rotating and charged black holes in Einstein gravity.