DD-dimensional Bardeen-AdS black holes in Einstein-Gauss-Bonnet theory

We present a $D$-dimensional Bardeen like Anti-de Sitter (AdS) black hole solution in Einstein-Gauss-Bonnet (EGB) gravity, \textit{viz}., Bardeen-EGB-AdS black holes. The Bardeen-EGB-AdS black hole has an additional parameter due to charge ($e$), apart from mass ($M$) and Gauss-Bonnet parameter ($\alpha$). Interestingly, for each value of $\alpha$, there exist a critical $e = e_E$ which corresponds to an extremal regular black hole with degenerate horizons, while for $e< e_E$, it describes non-extremal black hole with two horizons. Despite the complicated solution, the thermodynamical quantities, like temperature ($T$), specific heat($C$) and entropy ($S$) associated with the black hole are obtained exactly. It turns out that the heat capacity diverges at critical horizon radius $r_+ = r_C$, where the temperature attains maximum value and the Hawking-Page transition is achievable. Thus, we have an exact $D$-dimensional regular black holes, when evaporates lead to a thermodynamical stable remnant.Comment: 25 pages, 48 figure

Noncommutative geometry inspired rotating black string

Noncommutativity is an idea dating back to the early times of Quantum Mechanics and that string theory induced noncommutative (NC) geometry which provides an effective framework to study short distance spacetime dynamics. Also, string theory, a candidate for a consistent quantum theory of gravity, admits a variety of classical black hole solutions including black strings. In this paper, we study a NC geometry inspired rotating black string to cylindrical spacetime with a source given by a Gaussian distribution of mass. The resulting metric is a regular, i.e. curvature-singularity free, rotating black string, that in large $r$ limit interpolates Lemos \cite{lemos96} black string. Thermodynamical properties of the black strings are also investigated and exact expressions for the temperature, the entropy and the heat capacity are obtained. Owing to the NC correction in the solution, the thermodynamic quantities have been also modified and that the NC geometry inspired black string is always thermodynamically stable.Comment: 19 pages, 11 figure

Logarithmic Corrections to the Entropy of Scalar Field in BTZ Black Hole Space-time

The entanglement entropy correlates two quantum sub-systems which are the part of the larger system. A logarithmic divergence term present in the entanglement entropy is universal in nature and directly proportional to the conformal anomaly. We study this logarithmic divergence term of entropy for massive scalar field in $(2+1)$ dimension by applying numerical techniques to entanglement entropy approach. This (2+1) dimensional massive theory can be obtained from (3+1) dimensional massless scalar field via dimensional reduction. We also calculated mass corrections to entanglement entropy for scalar field. Finally, we observe that the area law contribution to the entanglement entropy is not affected by this mass term and the universal quantities depends upon the basic properties of the system.Comment: 15 pages, 3 figures, Title changed, reference adde

AVAILABILITY, ACCESSIBILITY AND SATISFACTION OF USERS OF INFORMATION RESOURCES SIN THE FACULTY OF AGRICULTURE UNIVERSITY LIBRARIES BY NON-ACADEMIC STAFFS OF OAU AND UI, NIGERIA

The study was conducted to investigate the Availability, Accessibility and Satisfaction of Users of Information Resources in the Faculty of Agriculture University Libraries by Non-Academic Staffs of OAU and UI, Nigeria. Three research objectives guided the study. 380 copies of questionnaire were distributed to the respondents in the faculty of agriculture university libraries and in response only 315 (82.89%) were received from the nonacademic staffs. stratified random sampling technique was employed for the study due to the largeness of the population. In the data analysis, frequency counts, simple percentages, and charts were used for the statistical analysis. The findings revealed that the access to information resources such as newspapers, journals, text and reference books, theses and dissertations, E-journals, E-News papers, E-Books and CD-ROMs; It also indicated that the level of usage of information resources for research among non academic is relatively fair and textbook, journals, E-Newspapers and E-theses/dissertations are the most used information resource by the non academic staff. The findings show that many other primary and secondary information resources and as for as digital sources and the internet facilities concerned, connection speed is challenging reflects in the use of electronic information resources in the library. The non- accessibility of digital and some printed information resources affects the non academic’s creativity. The research findings draw the attention of the Faculty of agriculture University Libraries (OAU and UI) in collection developments in terms of both the print and digital information resources and also recommend increasing the speed of internet and free downloading and printing the digital contents. The study also advocates the library staff members to provide information guidance and training services to the academic staff in utilizing the open databases such as AGORA, 9TAGRIS AGRICOLA, PubMed, Biomed Central9T 9TBEAST CD, VET CD, TEEAL, AGRICOLA9T

(Anti-)BRST Symmetries in FLRW Model: Supervariable Approach

We derive the off-shell nilpotent and absolutely anticommuting (anti-)BRST symmetry transformations corresponding to the local time-reparametrization symmetry transformation of the $(0+1)$-dimensional (1D) diffeomorphism (i.e. time-reparameterization) invariant FRLW model within the framework of supervariable approach BRST formalism. An application of (super-)diffeomorphism invariance yields horizontality conditions. The celebrated CF-type of condition which emerges as an off-shoot of the horizontality condition provides the absolute anticommutativity of the (anti-)BRST transformations. In addition, this CF-type condition is required for the derivation of coupled (but equivalent) Lagrangians. We also capture the (anti-)BRST invariance of the Lagrangians in terms of the Grassmannian translational generators and supervariables.Comment: 20 pages, 0 figur

Charged AdSAdS Black Holes in 4D4D Einstein--Gauss--Bonnet Massive Gravity

We investigate Einstein--Gauss--Bonnet--Maxwell massive gravity in $4D$ AdS background and find an exact black hole solution. The horizon structure of the black holes studied. Treating the cosmological constant as pressure and Gauss-Bonnet coupling parameters, and massive gravity parameters as variables, we drive the first law of black hole thermodynamics. To study the global stability of the black holes we compute the Gibbs free energy. The local stability of the black hole is also studied through specific heat. We analyze the effects of graviton mass and Gauss-Bonnet coupling parameters on the phase transition of the black holes. Finally, the effects of graviton mass and massive gravity parameters on the Joule-Thomson expansion of the black hole are studied.Comment: 32 pages, 51 captioned figures, Published in Eur. Phys. J. Plu

Five dimensional rotating regular black holes and shadow

We present an exact five-dimensional ($5D$) rotating regular black hole metric, with a deviation parameter $k\geq 0$, that interpolates between the $5D$ Kerr black hole ($k=0$) and $5D$ Kerr-Newman ($r \gg k$). This $5D$ rotating regular black hole is an exact solution of general relativity coupled to nonlinear electrodynamics. Interestingly, for a given value of parameter $k$ there exits a critical angular momentum $a=a_E$ which corresponds to extremal rotating regular black hole with degenerate horizons, while for $a<a_E$, one has non-extremal rotating regular black hole with outer and inner horizons. Owing to the correction factor ($e^{-k/r^2}$), which is motivated by the quantum arguments, the ergoregion and black hole shadow are modified.Comment: 23 pages, 9 figure