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Author (up) Araujo Filho, A.A. url  doi
openurl 
  Title Thermodynamics of massless particles in curved spacetime Type Journal Article
  Year 2023 Publication International Journal of Geometric Methods in Modern Physics Abbreviated Journal Int. J. Geom. Methods Mod. Phys.  
  Volume 12 Issue 13 Pages 2350226 - 40pp  
  Keywords Einstein-aether; thermodynamic properties; curved spacetime  
  Abstract This work is devoted to study the behavior of massless particles within the context of curved spacetime. In essence, we investigate the consequences of the scale factor C(?) of the Friedmann-Robertson-Walker metric in the Einstein-aether formalism to study photon-like particles. To do so, we consider the system within the canonical ensemble formalism in order to derive the following thermodynamic state quantities: spectral radiance, Helmholtz free energy, pressure, entropy, mean energy and the heat capacity. Moreover, the correction to the Stefan-Boltzmann law and the equation of states are also provided. Particularly, we separate our study within three distinct cases, i.e. s = 0, p = 0; s = 1, p = 1; s = 2, p = 1. In the first one, the results are derived numerically. Nevertheless, for the rest of the cases, all the calculations are accomplished analytically showing explicitly the dependence of the scale factor C(?) and the Riemann zeta function ?(s). Furthermore, our analyses are accomplished in general taking into account three different regimes of temperature of the universe, i.e. the inflationary era (T = 10(13)GeV), the electroweak epoch (T = 10(3)GeV) and the cosmic microwave background (T = 10(-13)GeV).  
  Address [Araujo Filho, A. A.] Univ Fed Cearra UFC, Dept Fis, Campus Pici,CP 6030, BR-60455760 Fortaleza, CE, Brazil, Email: dilto@fisica.ufc.br  
  Corporate Author Thesis  
  Publisher World Scientific Publ Co Pte Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0219-8878 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:001048378900001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5613  
Permanent link to this record
 

 
Author (up) Araujo Filho, A.A.; Reis, J.A.A.S.; Ghosh, S. url  doi
openurl 
  Title Quantum gases on a torus Type Journal Article
  Year 2023 Publication International Journal of Geometric Methods in Modern Physics Abbreviated Journal Int. J. Geom. Methods Mod. Phys.  
  Volume 20 Issue 10 Pages 2350178 - 19pp  
  Keywords Thermodynamic properties; non-Cartesian geometries; grand canonical ensemble; noninteracting and interacting quantum gases; spinless; bosons and fermion particles  
  Abstract This paper is aimed at studying the thermodynamic properties of quantum gases confined to a torus. To do that, we consider noninteracting gases within the grand canonical ensemble formalism. In this context, fermions and bosons are taken into account and the calculations are properly provided in both analytical and numerical manners. In particular, the system turns out to be sensitive to the topological parameter under consideration: the winding number. Furthermore, we also derive a model in order to take into account interacting quantum gases. To corroborate our results, we implement such a method for two different scenarios: a ring and a torus.  
  Address [Araujo Filho, A. A.] Univ Fed Ceara UFC, Dept Fis, Campus Pici,CP 6030, BR-60455760 Fortaleza, CE, Brazil, Email: dilto@fisica.ufc.br;  
  Corporate Author Thesis  
  Publisher World Scientific Publ Co Pte Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0219-8878 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000988814200003 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5553  
Permanent link to this record
 

 
Author (up) Capozziello, S.; Harko, T.; Lobo, F.S.N.; Olmo, G.J.; Vignolo, S. url  doi
openurl 
  Title The Cauchy problem in hybrid metric-Palatini f(X)-gravity Type Journal Article
  Year 2014 Publication International Journal of Geometric Methods in Modern Physics Abbreviated Journal Int. J. Geom. Methods Mod. Phys.  
  Volume 11 Issue 5 Pages 1450042 - 12pp  
  Keywords Cauchy problem; modified gravity; hybrid metric-Palatini gravity  
  Abstract The well-formulation and the well-posedness of the Cauchy problem are discussed for hybrid metric-Palatini gravity, a recently proposed modified gravitational theory consisting of adding to the Einstein-Hilbert Lagrangian an f(R)-term constructed a la Palatini. The theory can be recast as a scalar-tensor one predicting the existence of a light long-range scalar field that evades the local Solar System tests and is able to modify galactic and cosmological dynamics, leading to the late-time cosmic acceleration. In this work, adopting generalized harmonic coordinates, we show that the initial value problem can always be well-formulated and, furthermore, can be well-posed depending on the adopted matter sources.  
  Address [Capozziello, Salvatore] Univ Naples Federico II, Dipartimento Sci Fis, Naples, Italy, Email: capozzie@na.infn.it;  
  Corporate Author Thesis  
  Publisher World Scientific Publ Co Pte Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0219-8878 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000336527100003 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1813  
Permanent link to this record
 

 
Author (up) Izadi, A.; Shacker, S.S.; Olmo, G.J.; Banerjee, R. url  doi
openurl 
  Title Observational effects of varying speed of light in quadratic gravity cosmological models Type Journal Article
  Year 2018 Publication International Journal of Geometric Methods in Modern Physics Abbreviated Journal Int. J. Geom. Methods Mod. Phys.  
  Volume 15 Issue 5 Pages 1850084 - 16pp  
  Keywords Palatini formalism; modified gravity; causal structure constant; varying speed of light  
  Abstract We study different manifestations of the speed of light in theories of gravity where metric and connection are regarded as independent fields. We find that for a generic gravity theory in a frame with locally vanishing affine connection, the usual degeneracy between different manifestations of the speed of light is broken. In particular, the space-time causal structure constant (c(ST)) may become variable in that local frame. For theories of the form f(R, R-mu nu R-mu nu), this variation in c(ST) has an impact on the definition of the luminosity distance (and distance modulus), which can be used to confront the predictions of particular models against Supernovae type Ia (SN Ia) data. We carry out this test for a quadratic gravity model without cosmological constant assuming (i) a constant speed of light and (ii) a varying speed of light (VSL), and find that the latter scenario is favored by the data.  
  Address [Izadi, Azam] Khajeh Nasir Toosi Univ Technol, Dept Phys, Tehran, Iran, Email: aizadi@kntu.ac.ir;  
  Corporate Author Thesis  
  Publisher World Scientific Publ Co Pte Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0219-8878 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000429106400016 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 3553  
Permanent link to this record
 

 
Author (up) Sepehri, A.; Pincak, R.; Olmo, G.J. doi  openurl
  Title M-theory, graphene-branes and superconducting wormholes Type Journal Article
  Year 2017 Publication International Journal of Geometric Methods in Modern Physics Abbreviated Journal Int. J. Geom. Methods Mod. Phys.  
  Volume 14 Issue 11 Pages 1750167 - 32pp  
  Keywords M-theory; wormholes; graphene; superconductors  
  Abstract Exploiting an M-brane system whose structure and symmetries are inspired by those of graphene (what we call a graphene-brane), we propose here a similitude between two layers of graphene joined by a nanotube and wormholes scenarios in the brane world. By using the symmetries and mathematical properties of the M-brane system, we show here how to possibly increase its conductivity, to the point of making it as a superconductor. The questions of whether and under which condition this might point to the corresponding real graphene structures becoming superconducting are briefly outlined.  
  Address [Sepehri, Alireza] Shahid Bahonar Univ, Fac Phys, POB 76175, Kerman, Iran, Email: alireza.sepehri@uk.ac.ir;  
  Corporate Author Thesis  
  Publisher World Scientific Publ Co Pte Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0219-8878 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000413442500018 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 3334  
Permanent link to this record
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