This paper investigates the impact of generalized Maxwell-Boltzmann distributions, based on Mittag-Leffler functions, on the Chandrasekhar condition and Gamow temperature in astrophysical systems. Our findings reveal that the maximum allowable radiation pressure at the core of a star with a given mass is not solely determined by the mass itself but also exhibits a nontrivial dependence on the parameter <italic>&#947;</italic> and the fugacity <italic>z</italic>. Notably, the classical Chandrasekhar condition is recovered in the limit <italic>&#947;</italic>&#8239;&#8594;&#8239;1, validating the consistency of the model. These results offer new insights into the role of generalized statistical mechanics in stellar stability and nuclear reaction thresholds in dense astrophysical environments.

Türkiye

Mustafa Senay

Iran

Maryam Seifi

Hosein Mohammadzadeh

Chandrasekhar condition and Gamow temperature in the generalized Maxwell-Boltzmann distribution

We study circular orbits of charged particles in spherically symmetric AdS black holes in higher derivative theories of gravity, and their limiting ISCOs (innermost stable circular orbits). The dual interpretation is in terms of heavy-light double twist conformal field theory (CFT) operators in the large spin limit, whose anomalous dimensions can be extracted from the binding energy of charged probes in the bulk, in a certain large orbit limit. Demanding the positivity of the anomalous dimensions, leads to an exact bound for the charge to mass ratio <math altimg='si1.svg'><mover accent='true'><mrow><mi>q</mi></mrow><mrow><mo stretchy='false'>&#710;</mo></mrow></mover></math> of probe particles in the black hole backgrounds, which matches with the WGC bound. We find that <math altimg='si1.svg'><mover accent='true'><mrow><mi>q</mi></mrow><mrow><mo stretchy='false'>&#710;</mo></mrow></mover></math> increases with the higher derivative coupling parameters, which is explicitly checked in the Gauss-Bonnet gravity. For existing computations with probe particles in AdS backgrounds, the anomalous dimension and the WGC bound we find, particularly in Gauss-Bonnet theories, are in agreement in appropriate limits with the recent computations for Schwarzschild AdS <cross-ref refid='br0010' id='crf0040'>[1]</cross-ref>, charged AdS <cross-ref refid='br0020' id='crf0050'>[2]</cross-ref> and neutral Gauss-Bonnet black holes in AdS <cross-ref refid='br0030' id='crf0060'>[3]</cross-ref>. Finally, we show that the ISCOs exist until the limit set by the WGC bound, with their radius decreasing with coupling parameters, which we check explicitly for the case of Gauss-Bonnet black holes in AdS.

India

Adrinil Paul

Chandrasekhar Bhamidipati

ISCOs and the weak gravity conjecture bound in higher derivative theories of gravity

Cardy-Verlinde (CV) formula relates the entropy of a strongly coupled conformal field theory (CFT) possessing AdS dual, at finite temperature, to its total energy (with an appropriate insertion of additional internal energy for charged systems) and Casimir energy. While the CV formula has been checked for various CFTs, in the present work, we intend to verify it directly, by exploiting a phenomenological matrix model, which is believed to qualitatively capture features of strongly coupled <math><mi>N</mi><mo>=</mo><mn>4</mn><mo>,</mo><mi>S</mi><mi>U</mi><mo>(</mo><mi>N</mi><mo>)</mo></math> Super Yang-Mills theory on <math><msup><mrow><mi>S</mi></mrow><mrow><mn>3</mn></mrow></msup></math>, at finite temperature and chemical potential at large N.

Pavan Kumar Yerra

Sudipta Mukherji

Cardy-Verlinde formula from boundary matrix model

Computation of topological charges of the Schwarzschild and charged black holes in AdS in canonical and grand canonical ensembles allows for a classification of the phase transition points via the Bragg-Williams off-shell free energy. We attempt a topological classification of the critical points and the equilibrium phases of the dual gauge theory via a phenomenological matrix model, which captures the features of the  $$\mathcal{N}$$  = 4, SU(N) Super Yang-Mills theory on S 3 at finite temperature at large N. With minimal modification of parameters, critical points of the matrix model at finite chemical potential can be classified as well. The topological charges of locally stable and unstable dynamical phases of the system turn out to be opposite to each other, totalling to zero, and this matches the analysis in the bulk.

Pavan Yerra

Topology of critical points in boundary matrix duals

Sign and magnitude of the thermodynamic curvature provides empirical information about the nature of microstructures of a general thermodynamic system. For charged black holes in anti–de Sitter (AdS), thermodynamic curvature is positive for large charge or chemical potential, and diverges for extremal black holes, indicating strongly repulsive nature. We compute the thermodynamic curvature at low temperatures, for charged black holes with <math><mrow><msub><mrow><mi>AdS</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math> near horizon geometry, and containing a zero temperature horizon radius <math><msub><mi>r</mi><mi>h</mi></msub></math>, in a spacetime which asymptotically approaches <math><msub><mi>AdS</mi><mi>D</mi></msub></math> (for <math><mi>D</mi><mo>&gt;</mo><mn>3</mn></math>). In the semiclassical analysis at low temperatures, the curvature shows a novel crossover from negative to positive side, indicating the shift from attraction to repulsion dominated regime near <math><mi>T</mi><mo>=</mo><mn>0</mn></math>, before diverging as <math><mn>1</mn><mo>/</mo><mo>(</mo><mi>γ</mi><mi>T</mi><mo>)</mo></math>, where <math><mi>γ</mi></math> is the coefficient of leading low temperature correction to entropy. Accounting for quantum fluctuations, the curvature computed in the canonical ensemble is positive, whereas the one in the grand canonical ensemble, shows a crossover from negative to positive side in the Schwarzian region. Moreover, the divergence of curvature at <math><mi>T</mi><mo>=</mo><mn>0</mn></math> is cured irrespective of the ensemble used, resulting in a universal constant, inversely related to the number of symmetry generators of vacuum <math><mrow><msub><mrow><mi>AdS</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math>.

Aditya Singh

Poulami Mukherjee

Czechia

Thermodynamic curvature of charged black holes with <math><mrow><msub><mrow><mi>AdS</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math> horizons

The topological classification of critical points of black holes in 4D Einstein-Gauss-Bonnet gravity coupled to Born-Infeld theory is investigated. Considered independently, Born-infeld corrections to the Einstein action alter the topological charge of critical points of the charged AdS black hole system, whereas the Gauss-Bonnet corrections do not. For the combined system though, the topological charge of the Einstein-Gauss-Bonnet theory is unaltered in the presence of Born-Infeld coupling.

Topology of Born-Infeld AdS black holes in 4D novel Einstein-Gauss-Bonnet gravity

Using the Bragg-Williams construction of an off-shell free energy, we calculate the topological charge of the Hawking-Page transition point for black holes in anti–de Sitter. A computation following from a related off-shell effective potential in the boundary gauge dual matches the value of topological charge obtained in the bulk. We also work out the topological charges of the equilibrium phases of these systems, which follow from the saddle points of the appropriate free energy. The locally stable and unstable phases turn out to have topological charges opposite to each other, with the total being zero, in agreement with the result obtained from a recent construction [S.-W. Wei, Y.-X. Liu, and R. B. Mann, arXiv:2208.01932].

Topology of critical points and Hawking-Page transition

The usual generalized uncertainty principle will lead to a divergent mass limit of white dwarf, and this divergence should be prevented for both scenarios including positive and negative parameters of generalized uncertainty principle. Although it has been shown that negative parameter can directly restore the mass limit, the underlying reason is not given to explain why the negative sign appears under the condition of white dwarf. In order to solve this problem, we derive a field-dependent parameter expression whose sign can change depending on the species of spin fields. Besides, we find that the actual physical effect of the negative sign is aimed at limiting the exorbitant uncertainty of momentum.

China

Xin-Dong Du

Chao-Yun Long

Removing the divergence of Chandrasekhar limit caused by generalized uncertainty principle

An ‘open’ or <math><mo>(</mo><mi>μ</mi><mo>,</mo><mi>P</mi><mo>,</mo><mi>T</mi><mo>)</mo></math>-ensemble describes equilibrium systems whose control parameters are chemical potential μ, pressure P and temperature T. Such an unconstrained ensemble is seldom used for applications to standard thermodynamic systems due to the fact that the corresponding free energy identically vanishes as a result of the Euler relation. However, an open ensemble is perfectly regular for the case of black holes, as the entropy is a quasi-homogeneous function of extensive thermodynamic variables with scaling dictated by the Smarr formula. Following a brief discussion on thermodynamics in the open ensemble, we compute the general form of logarithmic corrections to the entropy of a typical system, due to fluctuations in energy, thermodynamic volume and a generic charge N. This is then used to obtain the exact analytic form of the logarithmically corrected black hole entropy for charged and rotating black holes in anti-de Sitter spacetimes.

Aritra Ghosh

Logarithmic corrections to the entropy function of black holes in the open ensemble

The aim of this note is to explore Susskind's proposal [1] on the connection between operator size in chaotic theories and the bulk momentum of a particle falling into black holes (see also [2–6] for more recent generalizations), in a broad class of models involving Gauss-Bonnet(GB) and Lifshitz-Hyperscaling violating theories in AdS. For Gauss-Bonnet black holes, the operator size is seen to be suppressed as the coupling constant λ is increased. For the Lifshitz-hyperscaling violating theories characterised by the parameters z and θ, the operator size is higher as compared to case <math><mi>z</mi><mo>=</mo><mn>1</mn><mo>,</mo><mi>θ</mi><mo>=</mo><mn>0</mn></math> (Reissner-Nordstrom AdS black holes). In the case of operators with global charge corresponding to charged particles falling into black holes, suppression of chaos is seen in general theories of gravity, in conformity with the original proposal [1] and earlier findings [3].