International Journal of Modern Physics D最新文献

{"title":"Cosmological dynamics and observational constraints on a viable f(Q) nonmetric gravity model","authors":"A. Oliveros, Mario A. Acero","doi":"10.1142/s0218271824500044","DOIUrl":"https://doi.org/10.1142/s0218271824500044","url":null,"abstract":"<p>Inspired by an exponential <span><math altimg=\"eq-00003.gif\" display=\"inline\" overflow=\"scroll\"><mi>f</mi><mo stretchy=\"false\">(</mo><mi>R</mi><mo stretchy=\"false\">)</mo></math></span><span></span> gravity model studied in the literature, in this work we introduce a new and viable <span><math altimg=\"eq-00004.gif\" display=\"inline\" overflow=\"scroll\"><mi>f</mi><mo stretchy=\"false\">(</mo><mi>Q</mi><mo stretchy=\"false\">)</mo></math></span><span></span> gravity model, which can be represented as a perturbation of <span><math altimg=\"eq-00005.gif\" display=\"inline\" overflow=\"scroll\"><mi mathvariant=\"normal\">Λ</mi></math></span><span></span>CDM. Typically, within the realm of <span><math altimg=\"eq-00006.gif\" display=\"inline\" overflow=\"scroll\"><mi>f</mi><mo stretchy=\"false\">(</mo><mi>Q</mi><mo stretchy=\"false\">)</mo></math></span><span></span> gravity, the customary approach to investigate cosmological evolution involves employing a parametrization of the Hubble expansion rate in terms of the redshift, <span><math altimg=\"eq-00007.gif\" display=\"inline\" overflow=\"scroll\"><mi>H</mi><mo stretchy=\"false\">(</mo><mi>z</mi><mo stretchy=\"false\">)</mo></math></span><span></span>, among other strategies. In this work, we have implemented a different strategy, deriving an analytical approximation for <span><math altimg=\"eq-00008.gif\" display=\"inline\" overflow=\"scroll\"><mi>H</mi><mo stretchy=\"false\">(</mo><mi>z</mi><mo stretchy=\"false\">)</mo></math></span><span></span>, from which we deduce approximated analytical expressions for the parameters <span><math altimg=\"eq-00009.gif\" display=\"inline\" overflow=\"scroll\"><msub><mrow><mi>w</mi></mrow><mrow><mstyle><mtext mathvariant=\"normal\">DE</mtext></mstyle></mrow></msub></math></span><span></span>, <span><math altimg=\"eq-00010.gif\" display=\"inline\" overflow=\"scroll\"><msub><mrow><mi>w</mi></mrow><mrow><mstyle><mtext mathvariant=\"normal\">eff</mtext></mstyle></mrow></msub></math></span><span></span> and <span><math altimg=\"eq-00011.gif\" display=\"inline\" overflow=\"scroll\"><msub><mrow><mi mathvariant=\"normal\">Ω</mi></mrow><mrow><mstyle><mtext mathvariant=\"normal\">DE</mtext></mstyle></mrow></msub></math></span><span></span>, as well as the deceleration parameter <i>q</i>. In order to verify the viability of this approximate analytical solution, we examined the behavior of these parameters in the late-time regime, in terms of the free parameter of the model, <i>b</i>. We find that for <span><math altimg=\"eq-00012.gif\" display=\"inline\" overflow=\"scroll\"><mi>b</mi><mo>></mo><mn>0</mn></math></span><span></span>, <span><math altimg=\"eq-00013.gif\" display=\"inline\" overflow=\"scroll\"><msub><mrow><mi>w</mi></mrow><mrow><mstyle><mtext mathvariant=\"normal\">DE</mtext></mstyle></mrow></msub></math></span><span></span> shows a quintessence-like behavior, while for <span><math altimg=\"eq-00014.gif\" display=\"inline\" overflow=\"scroll\"><mi>b</mi><mo><</mo><mn>0</mn></math></span><span></span>, it shows a phantom-like behavior. However,","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":"44 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140125644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unimodular-like times, evolution and Brans–Dicke gravity","authors":"Paolo M. Bassani, João Magueijo","doi":"10.1142/s0218271823501134","DOIUrl":"https://doi.org/10.1142/s0218271823501134","url":null,"abstract":"<p>In unimodular-like theories, the constants of nature are demoted from pre-given parameters to phase space variables. Their canonical duals provide physical time variables. We investigate how this interacts with an alternative approach to varying constants, where they are replaced by dynamical scalar fields. Specifically, we investigate the Brans–Dicke theory of gravity and its interaction with clocks dual to the cosmological constant, the Planck mass, etc. We crucially distinguish between the different role of Newton’s <i>G</i> in this process, leading to the possibility of local Lorentz invariance violation. A large number of possible theories emerge, for example where the Brans–Dicke coupling, <span><math altimg=\"eq-00001.gif\" display=\"inline\" overflow=\"scroll\"><mi>ω</mi></math></span><span></span>, depends on unimodular-like times (in a generalization of scalar-tensor theories), or even become the dual variable to unimodular-like clocks ticking variations in other demoted constants, such as the cosmological constant. We scan the space of possible theories and select those most interesting regarding the joint variations of the Brans–Dicke <span><math altimg=\"eq-00002.gif\" display=\"inline\" overflow=\"scroll\"><mi>ω</mi></math></span><span></span> and other parameters, (such as the cosmological constant); and also regarding their energy conservation violation properties. This ground work is meant to provide the formalism for further developments, namely regarding cosmology, black holes and the cosmological constant problem.</p>","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":"8 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140125529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gravitational wave: Generation and detection techniques","authors":"Saibal Ray, R. Bhattacharya, Sanjay K. Sahay, Abdul Aziz, Amit Das","doi":"10.1142/s0218271823400060","DOIUrl":"https://doi.org/10.1142/s0218271823400060","url":null,"abstract":"<p>In this paper, we review the theoretical basis for generation of gravitational waves and the detection techniques used to detect a gravitational wave. To materialize this goal in a thorough way, we first start with a mathematical background for general relativity from which a clue for gravitational wave was conceived by Einstein. Thereafter, we give the classification scheme of gravitational waves such as (i) continuous gravitational waves, (ii) compact binary inspiral gravitational waves and (iii) stochastic gravitational wave. Necessary mathematical insight into gravitational waves from binaries is also dealt with which follows detection of gravitational waves based on the frequency classification. Ground-based observatories as well as space borne gravitational wave detectors are discussed in a length. We have provided an overview on the inflationary gravitational waves. In connection to data analysis by matched filtering there are a few highlights on the techniques, e.g. (i) random noise, (ii) power spectrum, (iii) shot noise and (iv) Gaussian noise. Optimal detection statistics for a gravitational wave detection is also in the pipeline of the discussion along with detailed necessity of the matched filter and deep learning.</p>","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":"38 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140105502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Primordial cosmology of an emergent-like universe from modified gravity: Reconstruction and phenomenology optimization with a genetic algorithm","authors":"V. K. Oikonomou, Gregory Kafanelis","doi":"10.1142/s0218271823501146","DOIUrl":"https://doi.org/10.1142/s0218271823501146","url":null,"abstract":"<p>General relativity has been the dominant paradigm theory of gravity for the last century, it manages to explain a plethora of astronomical and cosmological observations with high accuracy. A major challenge faced by general relativity is, that it predicts a singularity as the beginning of our universe. In this paper, we shall explore a well-known idea in the literature that of the emergent universe and its viability according to Planck 2018 data and BBN constraints.</p>","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":"9 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140125640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Equilibrium of charged fluid around a Kerr black hole immersed in a magnetic field: Variation of angular momentum","authors":"Audrey Trova","doi":"10.1142/s0218271823501122","DOIUrl":"https://doi.org/10.1142/s0218271823501122","url":null,"abstract":"<p>This work presents analytically constructed equilibrium structures of charged perfect fluids orbiting Kerr Black holes embedded in an asymptotically uniform magnetic field. Our focus is on the effect of the nonconstant angular momentum distribution through the disk, as well as its combined effect with the external magnetic field and the fluid charge. We demonstrate that the three parameters of our study have a significant impact on the various features of the accretion disk: the shape, the size of the disk and the characteristic of the fluid, as the pressure and the rest-mass density. Through our investigation, we observe substantial deviations from both the uncharged thick disk model and the charged disk model with constant angular momentum.</p>","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":"12 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140125558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A comparative study of wormhole models in f(R,T) gravity","authors":"Chanchal Chawla, A. Dixit, A. Pradhan, S. Krishnannair","doi":"10.1142/s0218271823501079","DOIUrl":"https://doi.org/10.1142/s0218271823501079","url":null,"abstract":"","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":"176 4","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138998349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nonlinear electrodynamical lensing of electromagnetic waves on the dipole magnetic field of the magnetar","authors":"Beisen Nurzada, M. Abishev, S. Toktarbay, T. Yernazarov, Yerlan Aimuratov, M. Khassanov","doi":"10.1142/s0218271823501067","DOIUrl":"https://doi.org/10.1142/s0218271823501067","url":null,"abstract":"","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":"88 7","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138999505","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Entanglement and Quantum teleportation in terms of Dirac modes observed by accelerated observers","authors":"Yue Dai, Yu Shi","doi":"10.1142/s0218271823501043","DOIUrl":"https://doi.org/10.1142/s0218271823501043","url":null,"abstract":"","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":"58 S9","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138996319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diffeomorphism invariance and quantum mechanical paradoxes","authors":"Adam Dukehart, David Mattingly","doi":"10.1142/s0218271823501092","DOIUrl":"https://doi.org/10.1142/s0218271823501092","url":null,"abstract":"","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":"14 6","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138970673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermal fluctuations of (non)linearly charged BTZ black hole in massive gravity","authors":"B. Pourhassan, S. H. Hendi, S. Upadhyay, I. Sakalli, E. Saridakis","doi":"10.1142/s0218271823501109","DOIUrl":"https://doi.org/10.1142/s0218271823501109","url":null,"abstract":"","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":"54 S6","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138996369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}