The late-time behavior of our universe is one accelerated expansion, or that a de Sitter space, and therefore motivates us to look for time-dependent backgrounds. Finding such backgrounds in string theory has always been challenging problem. An even harder problem find allow positive dark energies. As first step handle scenarios, we study background type IIB theory, with four-dimensional isometries, by uplifting it M-theory then realizing as coherent, squeezed-coherent, state over an...

We study two-point correlation functions of a massive free scalar field in de Sitter space using the heat kernel formalism. Focusing on two operators conjugate static patches we derive geodesic approximation to correlator valid for large mass and at late times. This expression involves sum over complex geodesics that correctly reproduces large-mass, late-time limit exact function Bunch-Davies vacuum. The exponential decay is associated timelike part geodesics. emphasize tension with finite...

We study the causal structure of Schwarzschild-de Sitter (SdS), including shock wave perturbations, in $D>3$ using reflected null ray trajectories, either through interior black hole or exterior de region. Specifically, we compute quasinormal mode frequencies eikonal, high-frequency, limit, by identifying `critical time', for arbitrary values mass. emphasize important role static sphere proper time normalization and related boundary conditions. The computed critical times indicate presence...

Abstract We provide further evidence to support the fact that a four‐dimensional effective field theory description with de Sitter isometries in IIB string theory, overcoming no‐go and swampland criteria, can only exist if space is realized as Glauber‐Sudarshan state. show here this result independent of choice slicings. The state, constructed by shifting interacting vacuum M‐theory uplift scenario, differs from standard coherent state QFT sense shape size changes respect time, implying...

Abstract It is shown in this article that an explicit construction of a four‐dimensional de Sitter space may be performed using diagrammatic approach via nodal diagrams emanating from the path integral representation Glauber‐Sudarshan state. Sum these typically leads to asymptotic series Gevrey kind which can then Borel resummed, thus reproducing non‐perturbative structure system. The analysis shows not only possible string theory overcoming no‐go and swampland criteria—albeit as state—but...

We argue that, in the presence of time-dependent fluxes and quantum corrections, four-dimensional de Sitter solutions should appear type IIB string landscape not swampland. Our construction considers generic choices local non-local terms satisfies no-go swampland criteria, latter being recently upgraded using trans-Planckian cosmic censorship. Interestingly, both time-independent Newton constant moduli stabilization may be achieved such backgrounds even internal spaces. However, once...

In this article, we point out that to solve the null Raychaudhuri equation for higher-dimensional spacetime with an accelerating FRW solution in external directions and static compact internal directions, it is necessary violate strong-energy condition higher dimensions. This constraint well-known obtaining cosmological solutions string compactification, first described by Gibbons-Maldacena-Nunez. deriving constraint, do not make any assumptions regarding matter content.

Abstract We analyze null- and spacelike radial geodesics in Schwarzschild-de Sitter spacetime connecting two conjugate static sphere observers, i.e. free-falling observers at a fixed radius between the horizons. explicitly determine changes causal structure with respect to these natural as result of inward bending black hole singularity, well outward asymptotic infinity. Notably, function mass, first increasing towards maximum then decreasing vanish extreme Nariai limit. For generic mass...

One of the fundamental challenges in string theory is to derive realistic four-dimensional cosmological backgrounds from it despite strict consistency conditions that constrain its possible low-energy backgrounds. In this work, we focus on energy as covariant and background-independent requirements order classify coming two steps. Firstly, show how supergravity actions obey many relevant under some reasonable assumptions. Remarkably, find are satisfied even presence objects which...

We study the Casimir effect for a three dimensional system of ideal free massive Bose gas in slab geometry with Zaremba and anti-periodic boundary conditions. It is found that these type conditions resulting force repulsive nature, contrast usual periodic, Dirichlet or Neumann condition where attractive (Martin P. A. Zagrebnov V. A., Europhys. Lett., 73 (2006) 15.). forces also maintain power law decay function below condensation temperature exponential above albeit positive sign,...

The segregating properties for FexCu1-x and CuxCo1-x liquid-liquid binary alloys are investigated theoretically. Here, the free energy of mixing is calculated by using electronic theory metals within framework perturbative approach. results such as critical temperature concentration agree well with available experimental data. Most importantly, present work confirms our previous finding [M. Mehedi Faruk G. M. Bhuiyan, Physica B 422, 56 (2013)] that volume dependent part mostly responsible...

We analyze four-dimensional Friedmann-Lemaître-Robertson-Walker cosmologies in type IIB, arising from a M-theory dual, and find that the null energy condition (NEC) has to be obeyed by them (except for negatively curved case) order action have Wilsonian effective description. However, this does not imply metric obey 11D NEC. Thus, we propose new swampland conjecture-the 4D NEC is consistency any theory completion within M theory-with an explicit derivation of it cosmological backgrounds...

Thermodynamic properties of ideal Bose gas trapped in an external generic power law potential are investigated systematically from the grand thermodynamic d dimensional space.The most general conditions for Bose-Einstein condensate and discontinuous heat capacity at critical temperature presence presented this manuscript.The dependence physical quantities on potential, particle characteristics space dimensionality discussed.The more results obtained paper presents a unified illustration...

A particular framework for quantum gravity is the doubly special relativity (DSR) formalism that introduces a new observer independent scale (the Planck scale). We resort to methods of statistical mechanics in this determine how deformed dispersion relation affects thermodynamics photon gas. The ensuing modifications density states, partition function, pressure, internal energy, entropy, free energy and specific heat are calculated. These results compared with outcome obtained Lorentz...

Thermodynamics of ideal Fermi gas trapped in an external generic power law potential U = d i=1 c i | xi ai ni are investigated systematically from the grand thermodynamic dimensional space.These properties explored deeply degenerate limit (µ >> K B T ), where greatly dominated by Pauli exclusion principle.Pressure and energy along with isothermal compressibility is non zero at 0K, denoting system quite live even absolute temperature.The nonzero value compressibilty denotes point pressure not...

We have investigated the Unruh effect in Anti de-Sitter (AdS) spacetime by examining response function of an Unruh-DeWitt particle detector with uniform constant acceleration. An exact expression for scalar field has been obtained different levels non-linearity even dimensional AdS spacetime. also showed how accelerated coupled quadratically to massless Dirac $D$ $(D \geq 2)$ is proportional that a linearly $2D$ Here, fermionic and matter minimally conformally background metric,...

In this article, we point out that to solve the null Raychaudhuri equation for higher dimensional spacetime with accelerating FRW solution in external directions and static compact internal directions, it is necessary violate Strong Energy condition dimensions. This constraint well-known obtaining cosmological solutions string compactification, first described by Gibbons-Maldacena-Nunez. deriving constraint, do not make any assumptions regarding matter content.

From the unified statistical thermodynamics of quantum gases, virial coefficients ideal Bose and Fermi trapped under generic power law potential are derived systematically. general result coefficients, one can produce known results in d = 3 2. But more importantly we found that, gases become identical (except second coefficient, where sign is different) when harmonic 1. This suggests equivalence between established 1 (J. Stat. Phys. DOI 10.1007/s10955-015-1344-4). Also, it that...

The changes in characteristics of Bose condensation ideal gas due to an external generic power law potential are studied carefully. Detailed calculation Kim et al. (J. Phys. Condens. Matter 11 (1999) 10269) yielded the hierarchy transitions with changing fractional dimensionality. In this manuscript, some theorems regarding specific heat at constant volume CV presented. Careful examination these reveal existence hidden transition trapped systems as well.

Average energy per fermion in case of Fermi gas with any kinematic characteristic, trapped under most general power law potential d dimension has been calculated at zero temperature.In a previous paper (M.Acharyya, Eur.J Phys. 31 L89 ( 2010)) it was shown, free ideal as increases average approaches to and infinite becomes equal T = 0.In this letter is shown that, for system finite the depends on exponent, but tends infinity coincides exponent.The result obtained manuscript more we can...

Abstract We study the finite time response of an Unruh–DeWitt particle detector described by a qubit (two-level system) moving with uniform constant acceleration in maximally symmetric spacetimes. The D dimensional massless fermionic function de Sitter (dS) background is found to be identical that linearly coupled scalar field 2 dS background. Furthermore, we visit status Huygen’s principle Unruh radiation observed detector.

Entropy bound for the photon gas in a noncommutative (NC) spacetime where phase space is with compact spatial momentum space, previously studied by Nozari et al., has been reexamined correct distribution function. While al. have employed Maxwell-Boltzmann function to investigate thermodynamic properties of gas, we function, that is, Bose-Einstein No such entropy observed if solve partition As result, reported analogy between thermodynamics NC and Bekenstein-Hawking black holes should be disregarded.