Abstract
Recently the present author introduced the notion of generalized quasi-conformal curvature tensor which bridges conformal curvature tensor, concircular curvature tensor, projective curvature tensor and conharmonic curvature tensor. The object of the present paper is to find out curvature conditions for which Ricci solitons in Sasakian manifolds are sometimes shrinking and some other time remain expanding.
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1 Introduction
In 1968, Yano and Sawaki [1] introduced the notion of quasi-conformal curvature tensor in the context of Riemannian geometry. Recently, in tune with Yano and Sawaki [1], the present author [2] introduced and studied generalized quasi-conformal curvature tensor in the context of \(N(k,\mu )\)-contact metric manifold. The beauty of generalized quasi-conformal curvature tensor lies in the fact that it has the flavour of Riemann curvature tensor R, conformal curvature tensor C [3], conharmonic curvature tensor \(\hat{C}\) [4], concircular curvature tensor E [5, p. 84], projective curvature tensor P [5, p. 84] and m-projective curvature tensor H[6] as particular cases. Hereafter in this paper, generalized quasi-conformal curvature tensor \(\mathcal {W}\) will be called quasi-conformal like curvature tensor.
The components of quasi-conformal like curvature tensor \(\mathcal {W} \) in a Riemannian manifold \((M^{2n+1},g)(n>1),\) are given by
where a, b and c are real constants. The foregoing equation can also be written as
R, S, Q and r being Riemannian curvature tensor, Ricci tensor, Ricci operator and scalar curvature respectively. In particular, the quasi conformal like curvature tensor \({\mathcal {W}}\) induced to (1) Riemann curvature tensor R if \(a=b=c=0\); (2) conformal curvature tensor C if \(a=b=-\frac{1}{2{n}-1}\) and \(c=1\); (3) conharmonic curvature tensor \(\hat{C},\) if \(a=b=-\frac{1}{2{n}-1}\) and \(c=0\); (4) concircular curvature tensor E, if \(a=b=0\) and \(c=1\); (5) projective curvature tensor P if \(a=-\frac{1}{2{n}},\) \(b=0\) and \(\ c=0\) and (6) m-projective curvature tensor H if \(a=b= -\frac{1 }{4{n}}\) and \(c=0\).
The study of the Ricci solitons in contact geometry has begun with the work of Sharma [7, 8]. Ricci solitons are introduced as triples (M, g, V), where (M, g) is a Riemannian manifold and V is a potential vector field so that the following equation is satisfied:
where \(\pounds \) denotes the Lie derivative, S is the Ricci tensor and \( \lambda \in \mathbb {R} \). A Ricci soliton is said to be shrinking, steady or expanding according to \( \lambda \) negative, zero, and positive respectively. During the last two decades, the geometry of Ricci solitons has become a subject of growing interest for many mathematicians. For details we refer to [9,10,11,12,13,14,15,16,17,18,19,20] and the references therein. It has become more important after Grigory Perelman applied Ricci solitons to solve the long standing Poincar é conjecture posed in 1904.
Our work is structured as follows. Section 2 is a very brief review of Sasakian manifolds. In Sect. 3, we investigate Ricci solitons in a Sasakian manifold admitting \({\omega } (\xi ,X){ \cdot }\mathcal {W}=0\) where \(\omega \) and \({\mathcal {W}}\) stand for quasi conformal like curvature tensor with the associated scalar triples \((\bar{a},\bar{b},\bar{c})\) and (a, b, c) respectively (two distinct notions have been used in order to study the nature of 36 semi-symmetric type curvature condition [25] as shown in the table by taking the permutation and combination of the scalar triples into account), the dot means that \({\mathcal {\omega }}(X,Y)\) acts as a derivation on \(\mathcal {W}\). It is observed that that Ricci soliton \( (M,g,\xi )\) in a Sasakian manifold satisfying \({\omega }(\xi ,X )\cdot \mathcal {W}=0\) is sometime expanding and some other time remain shrinking. In Sect. 4, we have pointed out that Ricci soliton in a Sasakian manifold satisfying \(\mathcal {W}(\xi ,X)\cdot S=0\) is always shrinking. Remark that this type of conditions was discussed in [21, 22].
2 Sasakian manifolds
Let \(M^{2n+1}(\phi ,\xi ,\eta ,g)\) be a Sasakian manifold. Then the following relation hold [23, 24]
for any vector fields X, Y, Z on M, where \(\nabla \) denotes the operator of covariant differentiation with respect to g.
Let \((g,V,\lambda )\) be a Ricci soliton in an \((2n+1)\)-dimensional Sasakian manifold M. From (2.3), we have
From (1.3) and (2.5), we find that
Thus, in a Sasaskian manifold with Ricci soliton, the quasi conformal like curvature tensor \(\mathcal {W}\) takes the form
where Q and r are respectively the Ricci operator and the scalar curvature on M.
3 Ricci solitons in Sasakian manifolds satisfying \({\mathcal {\omega }}({X,Y} ){\cdot }{\mathcal {W}}{=0}\)
Let us consider a \((2n+1)\)-dimensional Sasakian manifold M, satisfying the condition
for any vector fields X, Y on the manifold and \({\mathcal {\omega } }(X,Y)\) acts on \({\mathcal {W}}\) as derivation, where \(\omega \) and \({\mathcal {W}}\) stand for quasi conformal like curvature tensor with the associated scalar triples \(( \bar{a},\bar{b},\bar{c})\) and (a, b, c) respectively (two distinct notions have been used in order to study the nature of 36 semi-symmetric type curvature condition [25] as shown in the table by taking the permutation and combination of the scalar triples into account). It is equivalent to
Putting \(X=Y=e_{i}\) in (3.2) where \(\{e_{1}, e_{2}, e_{3},\ldots ,e_{2{n}},\) \(e_{2{n}+1}=\xi \}\) is an orthonormal basis of the tangent space at each point of the manifold M and taking the summation over i, \(1\le i\le 2{n}+1,\) we get
From the Eqs. (2.3) and (2.7), we can easily bring out the followings
In view of (3.4) and (3.5), (3.6) becomes
As a consequence of (3.4)–(3.5), we obtain the followings
By virtue of (3.7), (3.8), (3.9) and (3.10), the Eq. (3.3) yields
for \(Z=U=\xi \). From the above equation, by taking permutation and combination of different values of \((\bar{a},\bar{b},\bar{c})\) and (a, b, c) (like 0, \(-\frac{1}{2n-1}\), \(-\frac{1}{2n}\), \(-\frac{1}{4n}\) etc.,) one will get 36 curvature conditions and we found that Ricci soliton \((M,g,\xi )\) in a Sasakian manifold for each curvature restriction is sometime expanding and some other time remain shrinking. This leads to the following:
Theorem 3.1
Ricci soliton \((M,g,\xi )\) in a Sasakian manifold satisfying \({\omega (}\xi ,X)\cdot {\mathcal {W}}=0\) is sometime expanding and some other time remain shrinking.
4 Sasakian manifolds with \({\mathcal {W}}\cdot S=0\)
Let \(M^{2n+1}(\phi ,\xi ,\eta ,g)(n>1),\) be a Sasakian manifold, satisfying the condition
Putting \(Z=\xi \) in (4.2) and then using (2.4), we get
In view of (2.7), we have
Making use of (4.4) in (4.3), we have
Contracting X over Y in (4.5), we get
From, the Eq. (4.6) one can easily bring out the following table
Curvature condition | Value of \(\lambda \) |
---|---|
\({ R(\xi ,X)\cdot S}=0\) (obtained by \(a=b=c=0\)) | \(\lambda =-2nk,\) |
\({ E(\xi ,X)\cdot S}=0\) (obtained by \(a=b=0,\) \(c=1\)) | \(\lambda =-2nk,\) |
\({ C(\xi ,X)\cdot S}=0\) (obtained by \(a=b=-\frac{1}{2n-1},c=1\)) | \( \lambda =-2nk,\) |
\({ \hat{C}(\xi ,X)\cdot S}=0\) (obtained by \(a=b=-\frac{1}{2n-1},c=0\)) | \(\lambda =-2nk,-\frac{2n-1}{2}\) |
\({ P(\xi ,X)\cdot S}=0\) (obtained by \(a=-\frac{1}{2n},b=c=0\)) | \(\lambda =-2nk,\) |
\({ H(\xi ,X)\cdot S}=0\) (obtained by \(a=b=-\frac{1}{4n},\) \(c=0\)) | \(\lambda =-2nk.\) |
From the above table, we can state the following:
Theorem 4.1
Ricci soliton \((M,g,\xi )\) in a Sasakian manifold admitting \(\mathcal { W\cdot }{ S}=0\) is always shrinking.
References
Yano, K., Sawaki, S.: Riemannian manifolds admitting a conformal transformation group. J. Differ. Geom. 2, 161–184 (1968)
Baishya, K.K., Chowdhury, P.R.: On generalized quasi-conformal \(N(k,\mu )\)-manifolds. Commun. Korean Math. Soc. 31(1), 163–176 (2016)
Eisenhart, L.P.: Riemannian Geometry. Princeton University Press, Princeton (1949)
Ishii, Y.: On conharmonic transformations. Tensor (N.S.) 7, 73–80 (1957)
Yano, K., Bochner, S.: Curvature and Betti Numbers. Annals of Mathematics Studies, vol. 32. Princeton University Press, Princeton (1953)
Pokhariyal, G.P., Mishra, R.S.: Curvature tensors and their relativistics significance. I. Yokohama Math. J. 18, 105–108 (1970)
Ghosh, A., Sharma, R., Cho, J.T.: Contact metric manifolds with \(\eta \)-parallel torsion tensor. Ann. Glob. Anal. Geom. 34(3), 287–299 (2008)
Sharma, R.: Certain results on K-contact and (k,\(\mu \) )-contact manifolds. J. Geom. 89, 138–147 (2008)
Chow, B., Lu, P., Ni, L.: Hamilton’s Ricci Flow, Graduate Studies in Mathematics, vol. 77. American Mathematical Society, Providence (2006)
Bejan, C.L., Crasmareanu, M.: Ricci solitons in manifolds with quasi-constant curvature. Publ. Math. Debr. 78(1), 235–243 (2011)
Bagewadi, C.S., Ingalahalli, G.: Ricci solitons in Lorentzian-Sasakian manifolds. Acta Math. Acad. Paed. N Y 28(1), 59–68 (2012)
Bagewadi, C.S., Ingalahalli, G., Ashoka, S.R.: A study on Ricci solitons in Kenmotsu manifolds. ISRN Geom. 2013, 412593 (2013)
Ingalahalli, G., Bagewadi, C.S.: Ricci solitons in \(\alpha \)-Sasakian manifolds. ISRN Geom 2012, 421384 (2012)
Nagaraja, H.G., Premalatha, C.R.: Ricci solitons in Kenmotsu manifolds. J. Math. Anal. 3(2), 18–24 (2012)
Cho, J.T., Kimura, M.: Ricci solitons and real hypersurfaces in a complex space form. Tohoku Math. J. 61(2), 205–212 (2009)
Baishya, K.K., Chowdhury, P.R.: \(\eta \)-Ricci solitons in \((LCS)_{n}\)-manifolds. Bull. Transilv. Univ. Brasov 9(58), 1–12 (2016)
Tripathi, M.M.: Ricci solitons in contact metric manifolds. arXiv:0801.4222
Deshmukh, S., Al-Sodais, H., Alodan, H.: A note on Ricci solitons. Balkan J. Geom. Appl. 16(1), 48–55 (2011)
De, U.C., Matsuyama, Y.: Ricci solitons and gradient Ricci solitons in a Kenmotsu manifolds. Southeast Asian Bull. Math. 37(5), 691–697 (2013)
Wang, Y., Liu, X.: Ricci solitons on three-dimensional \(\eta \)-Einstein almost Kenmotsu manifolds. Taiwan. J. Math. 19, 91–100 (2015)
Blaga, A.M.: Eta-Ricci solitons on para-Kenmotsu manifolds. Balkan J. Geom. Appl. 20(1), 1–13 (2015)
Blaga, A.M.: Eta-Ricci solitons on Lorentzian para-Sasakian manifolds. Filomat 30(2), 489–496 (2016)
He, C., Zhu, M.: The Ricci solitons on Sasakian manifolds. arXiv:1109.4407 (2011)
Blair, D.E.: Riemannian Geometry of Contact and Symplectic Manifolds. Birkhäuser, Boston (2002)
Szabó, Z.I.: Classification and construction of complete hypersurfaces satisfying \(R(X, Y)\cdot R=0\). Acta. Sci. Math. 47, 321–348 (1984)
Acknowledgements
The author is grateful to the referees for their valuable suggestions and remarks that definitely improved the paper. The author would also like to thank UGC, ERO Kolkata, for their financial support File No. PSW-194/15-16.
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Baishya, K.K. Ricci solitons in Sasakian manifold. Afr. Mat. 28, 1061–1066 (2017). https://doi.org/10.1007/s13370-017-0502-z
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DOI: https://doi.org/10.1007/s13370-017-0502-z
Keywords
- Sasakian manifold
- Quasi-conformal like curvature tensor
- Ricci solitons shrinking, steady and expanding