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SUMMARY:Gr.IV seminar: Henrik Jeldtoft Jensen (Imperial College\, UK) - "U
 niversality classes\, Thermodynamics of Group Entropies\, and Black Holes"
 .
DTSTART:20261002T140000Z
DTEND:20261002T150000Z
DTSTAMP:20261018T034000Z
UID:indico-event-53133@agenda.infn.it
DESCRIPTION:Conventional Boltzmann--Gibbs statistical mechanics successful
 ly describes systems with weak to moderate correlations\, where the number
  of accessible configurations W(N) grows exponentially with the number of 
 degrees of freedom N. However\, this framework breaks down for systems wit
 h strong correlations or long-range interactions\, for which the configura
 tion space exhibits non-exponential growth. While numerous generalized ent
 ropies have been proposed to address this limitation\, a coherent link to 
 classical thermodynamic laws has remained elusive. Here\, we propose group
  entropies as a unifying framework\, defining universality classes of entr
 opies through the asymptotic scaling of W(N)\, each yielding an extensive
  entropy. \nWe show that this approach provides the basis for a consisten
 t thermodynamic formulation beyond the Boltzmann--Gibbs paradigm. By expre
 ssing these entropies in terms of thermodynamic state variables\, we demon
 strate their consistency with classical thermodynamics\, in close analogy 
 to the emergence of the Clausius entropy from the Boltzmann--Gibbs formali
 sm. Focusing on the zeroth thermodynamic law\, we identify the empirical t
 emperature and\, by using Carathéodory's formulation of the second law\, 
 we derive the associated absolute temperature. As an application\, we anal
 yse black-hole thermodynamics using the extensive group entropy class corr
 esponding to stretched-exponential behaviour of W(N) and derive a negative
  heat capacity\, known to be a hallmark property of black holes. This resu
 lt holds for the stretched-exponential entropies associated with both the 
 Bekenstein—Hawking and Barrow entropy scalings.\n \nReferences \n[1] P
 . Tempesta\, Group entropies\, correlation laws\, and zeta functions. Ph
 ys. Rev. E 84\, 021121 (2011).\n[2] H.J. Jensen and P. Tempesta\, Group 
 Entropies as a Foundation for Entropies\, Entropy 26\, 266 (2024).\n[3] 
 Constantino Tsallis\, Henrik Jeldtoft Jensen\, Extensive composable entro
 py for the analysis of cosmological data. Phys. Lett. B\, 861\, 139238 (2
 025).\n[4] ] H.J. Jensen\, Pert Jizba\, and P. Tempesta\, Universality cl
 asses\, Thermodynamics of Group Entropies\, and Black Holes. arXiv:2603.0
 2385.\n\nhttps://agenda.infn.it/event/53133/
LOCATION:0M03
URL:https://agenda.infn.it/event/53133/
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