Screening $$\Lambda $$ Λ in a new modified gravity model
Abstract We study a new model of Energy-Momentum Squared Gravity (EMSG), called Energy-Momentum Log Gravity (EMLG), constructed by the addition of the term $$f(T_{\mu \nu }T^{\mu \nu })=\alpha \ln (\lambda \,T_{\mu \nu }T^{\mu \nu })$$ f(TμνTμν)=αln(λTμνTμν) , envisaged as a correction, to the Einst...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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SpringerOpen
2019-10-01
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| Series: | European Physical Journal C: Particles and Fields |
| Online Access: | http://link.springer.com/article/10.1140/epjc/s10052-019-7333-z |
| _version_ | 1819206900752842752 |
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| author | Özgür Akarsu John D. Barrow Charles V. R. Board N. Merve Uzun J. Alberto Vazquez |
| author_facet | Özgür Akarsu John D. Barrow Charles V. R. Board N. Merve Uzun J. Alberto Vazquez |
| author_sort | Özgür Akarsu |
| collection | DOAJ |
| description | Abstract We study a new model of Energy-Momentum Squared Gravity (EMSG), called Energy-Momentum Log Gravity (EMLG), constructed by the addition of the term $$f(T_{\mu \nu }T^{\mu \nu })=\alpha \ln (\lambda \,T_{\mu \nu }T^{\mu \nu })$$ f(TμνTμν)=αln(λTμνTμν) , envisaged as a correction, to the Einstein–Hilbert action with cosmological constant $$\Lambda $$ Λ . The choice of this modification is made as a specific way of including new terms in the right-hand side of the Einstein field equations, resulting in constant effective inertial mass density and, importantly, leading to an explicit exact solution of the matter energy density in terms of redshift. We look for viable cosmologies, in particular, an extension of the standard $$\Lambda $$ Λ CDM model. EMLG provides an effective dynamical dark energy passing below zero at large redshifts, accommodating a mechanism for screening $$\Lambda $$ Λ in this region, in line with suggestions for alleviating some of the tensions that arise between observational data sets within the standard $$\Lambda $$ Λ CDM model. We present a detailed theoretical investigation of the model and then constrain the free parameter $$\alpha '$$ α′ , a normalisation of $$\alpha $$ α , using the latest observational data. The data does not rule out the $$\Lambda $$ Λ CDM limit of our model ($$\alpha '= 0$$ α′=0 ), but prefers slightly negative values of the EMLG model parameter ($$\alpha '= -0.032\pm 0.043$$ α′=-0.032±0.043 ), which leads to the screening of $$\Lambda $$ Λ . We also discuss how EMLG relaxes the persistent tension that appears in the measurements of $$H_0$$ H0 within the standard $$\Lambda $$ Λ CDM model. |
| first_indexed | 2024-12-23T05:14:57Z |
| format | Article |
| id | doaj.art-ae82e9f56ad0405bb689e57a76cb17fe |
| institution | Directory Open Access Journal |
| issn | 1434-6044 1434-6052 |
| language | English |
| last_indexed | 2024-12-23T05:14:57Z |
| publishDate | 2019-10-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | European Physical Journal C: Particles and Fields |
| spelling | doaj.art-ae82e9f56ad0405bb689e57a76cb17fe2022-12-21T17:58:51ZengSpringerOpenEuropean Physical Journal C: Particles and Fields1434-60441434-60522019-10-01791011810.1140/epjc/s10052-019-7333-zScreening $$\Lambda $$ Λ in a new modified gravity modelÖzgür Akarsu0John D. Barrow1Charles V. R. Board2N. Merve Uzun3J. Alberto Vazquez4Department of Physics, Istanbul Technical UniversityDAMTP, Centre for Mathematical Sciences, University of CambridgeDAMTP, Centre for Mathematical Sciences, University of CambridgeDepartment of Physics, Boğaziçi UniversityInstituto de Ciencias Físicas, Universidad Nacional Autónoma de MéxicoAbstract We study a new model of Energy-Momentum Squared Gravity (EMSG), called Energy-Momentum Log Gravity (EMLG), constructed by the addition of the term $$f(T_{\mu \nu }T^{\mu \nu })=\alpha \ln (\lambda \,T_{\mu \nu }T^{\mu \nu })$$ f(TμνTμν)=αln(λTμνTμν) , envisaged as a correction, to the Einstein–Hilbert action with cosmological constant $$\Lambda $$ Λ . The choice of this modification is made as a specific way of including new terms in the right-hand side of the Einstein field equations, resulting in constant effective inertial mass density and, importantly, leading to an explicit exact solution of the matter energy density in terms of redshift. We look for viable cosmologies, in particular, an extension of the standard $$\Lambda $$ Λ CDM model. EMLG provides an effective dynamical dark energy passing below zero at large redshifts, accommodating a mechanism for screening $$\Lambda $$ Λ in this region, in line with suggestions for alleviating some of the tensions that arise between observational data sets within the standard $$\Lambda $$ Λ CDM model. We present a detailed theoretical investigation of the model and then constrain the free parameter $$\alpha '$$ α′ , a normalisation of $$\alpha $$ α , using the latest observational data. The data does not rule out the $$\Lambda $$ Λ CDM limit of our model ($$\alpha '= 0$$ α′=0 ), but prefers slightly negative values of the EMLG model parameter ($$\alpha '= -0.032\pm 0.043$$ α′=-0.032±0.043 ), which leads to the screening of $$\Lambda $$ Λ . We also discuss how EMLG relaxes the persistent tension that appears in the measurements of $$H_0$$ H0 within the standard $$\Lambda $$ Λ CDM model.http://link.springer.com/article/10.1140/epjc/s10052-019-7333-z |
| spellingShingle | Özgür Akarsu John D. Barrow Charles V. R. Board N. Merve Uzun J. Alberto Vazquez Screening $$\Lambda $$ Λ in a new modified gravity model European Physical Journal C: Particles and Fields |
| title | Screening $$\Lambda $$ Λ in a new modified gravity model |
| title_full | Screening $$\Lambda $$ Λ in a new modified gravity model |
| title_fullStr | Screening $$\Lambda $$ Λ in a new modified gravity model |
| title_full_unstemmed | Screening $$\Lambda $$ Λ in a new modified gravity model |
| title_short | Screening $$\Lambda $$ Λ in a new modified gravity model |
| title_sort | screening lambda λ in a new modified gravity model |
| url | http://link.springer.com/article/10.1140/epjc/s10052-019-7333-z |
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