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ORIGINAL RESEARCH article

Front. Phys., 18 May 2022
Sec. Statistical and Computational Physics
This article is part of the Research Topic Differential Geometric Methods in Modern Physics View all 7 articles

Estimation of Eigenvalues for the ψ-Laplace Operator on Bi-Slant Submanifolds of Sasakian Space Forms

Ali H. Alkhaldi
Ali H. Alkhaldi1*Meraj Ali Khan
Meraj Ali Khan2*Mohd. AquibMohd. Aquib3Lamia Saeed AlqahtaniLamia Saeed Alqahtani4
  • 1Department of Mathematics, College of Science, King Khalid University, Abha, Saudi Arabia
  • 2Department of Mathematics, University of Tabuk, Tabuk, Saudi Arabia
  • 3Department of Mathematics, Sri Venkateswara College, University of Delhi, New Delhi, India
  • 4Department of Mathematics, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia

This study attempts to establish new upper bounds on the mean curvature and constant sectional curvature of the first positive eigenvalue of the ψ − Laplacian operator on Riemannian manifolds. Various approaches are being used to find the first eigenvalue for the ψ − Laplacian operator on closed oriented bi-slant submanifolds in a Sasakian space form. We extend different Reilly-like inequalities to the ψ − Laplacian on bi-slant submanifolds in a unit sphere depending on our results for the Laplacian operator. The conclusion of this study considers some special cases as well.

1 Introduction

It is one of the most significant aspects of Riemannian geometry to determine the bounds of the Laplacian on a given manifold. One of the major objectives is to find the eigenvalue that arises as a solution of the Dirichlet or Neumann boundary value problems for curvature functions. Because different boundary conditions exist on a manifold, one can adopt a theoretical perspective to the Dirichlet boundary condition using the upper bound for the eigenvalue as a technique of analysis for the Laplacian’s appropriate bound on a given manifold. Assessing the eigenvalue for the Laplacian and ψ − Laplacian operators has been progressively well-known over a long time. The generalization of the usual Laplacian operator, which is an anisotropic mean curvature, was studied in [17]. Let K denote a complete noncompact Riemannian manifold and B signify the compact domain within K. Let λ1(B) > 0 be the first eigenvalue of the Dirichlet boundary value problem.

Δψ+λ/ψ=0inBandψ=0onB,

where Δ represents the Laplacian operator on the Riemannian manifold Km. The Reilly’s formula deals exclusively with the fundamental geometrical characteristics of a given manifold. This is generally acknowledged by the following statement. Let (Km, g) be a compact m − dimensional Riemannian manifold and λ1 denote the first nonzero eigenvalue of the Neumann problem.

Δψ+λψ=0,onKandψη=0onK,

where η is the outward normal on ∂Km.

As a result of Reilly [24], we have the following inequality for a manifold Km immersed in a Euclidean space with ∂Km = 0

λ11VolKmKmH2dV,

where H is the mean curvature vector of immersion Km into Rn, λ1 signifies the first nonzero eigenvalue of the Laplacian on Km, and dV represents the volume element of Km.

Zeng and He computed the upper bounds for the ψ − Laplace operator as it relates to the first eigenvalue for Finsher submanifolds in Minkowski space. The first eigenvalue of the Laplace operator on a closed manifold was described by Seto and Wei . Nevertheless, Du et al. [16] derived the generalized Reilly inequality and calculated the first nonzero eigenvalue of the ψ − Laplace operator. By adopting a very similar strategy, Blacker and Seto [3] demonstrated a Lichnero-type lower limit for the first nonzero eigenvalue of the ψ − Laplacian for Neumann and Dirichlet boundary conditions.

The studies [14, 15] illustrate the first nonnull Laplacian eigenvalue, which is considered an extension of Reilly’s work . The results of the distinct classes of Riemannian submanifolds for diverse ambient spaces show that the results of both first nonzero eigenvalues portray similar inequality and have the same upper bounds [13, 14]. In the case of the ambient manifold, it is known from past research that Laplace and ψ − Laplace operators on Riemannian manifolds played a vital role in accomplishing different achievements in Riemannian geometry (see [2, 5, 10, 11, 17, 22, 23,]).

The ψ − Laplacian on a m − dimensional Riemannian manifold Km is defined as

Δψ=div|h|ψ2h,

where ψ > 1 and if ψ = 2; then, the abovementioned formula becomes the usual Laplacian operator.

The eigenvalue of Δh, on the other hand, is Laplacian-like. If a function h ≠ 0 meets the following equation with Dirchilet boundary condition or Neumann boundary condition as discussed earlier

Δψh=λ|h|ψ2h,

where λ is a real number called the Dirichlet eigenvalue. In the same way, the previous requirements apply to the Neumann boundary condition.

Looking at Riemannian manifolds without boundaries, the Reilly-type inequality for the first nonzero eigenvalue λ1,ψ for ψ − Laplacian was computed in .

λ1,ψ=infK|h|qK|h|q:hW1,ψK10,K|h|ψ2h=0.

On the other hand, Chen was the first to propose the geometry of slant immersions as a logical extension of both holomorphic and totally real immersions. In addition, Lotta introduced the notion of slant submanifolds within the context of almost contact metric manifolds, and Cabrerizo et al. [9] delved more into these submanifolds. More precisely, Cabrerizo et al. explored slant submanifolds in the setting of Sasakian manifolds. However, Cabrerizo et al. introduced another generalization of slant and contact CR-submanifolds; that is, they proposed the idea of bi-slant and semi-slant submanifolds in the almost contact metric manifolds and provided several examples of these submanifolds.

After examining the literature, a logical question arises: can the Reilly-type inequalities for submanifolds of spheres be obtained using almost contact metric manifolds, as described in [1, 14, 15]? To answer this question, we explore the Reilly-type inequalities for bi-slant submanifolds isometrically immersed in a Sasakian space form M̄(κ) (odd dimensional sphere). To this end, our aim is to compute the bound for the first nonzero eigenvalues via ψ − Laplacian. The present study is led by the application of the Gauss equation and studies carried out in [13, 14, 16].

2 Preliminaries

A (2n + 1) − dimensional C − manifold K̄ is said to have an almost contact structure, if on K̄, there exists a tensor field ϕ of type (1, 1) and a vector field ξ and a 1-form η satisfying the following properties:

ϕ2=I+ηξ,ϕξ=0,η°ϕ=0,ηξ=1.

The manifold K̄ with the structure (ϕ, ξ, η) is called almost contact manifold. There exists a Riemannian metric g on an almost contact metric manifold K̄, satisfying the following relation

ηe1=ge1,ξ,gϕe1,ϕe2=ge1,e2e1ηe2,

for all e1,e2TK̄, where TK̄ is the tangent bundle of K̄.

An almost contact metric manifold K̄(ϕ,ξ,η,g) is said to be Sasakian manifold if it satisfies the following relation .

̄e1ϕe2=ge1,e2ξηe2e1,

for any e1,e2TK̄, where ̄ denotes the Riemannian connection of the metric g.

A Sasakian manifold K̄ is said to be a Sasakian space form if it has constant ϕ-holomorphic sectional curvature κ and is denoted by K̄(κ). The curvature tensor R̄ of the Sasakian space form K̄(κ) is given by [4].

R̄e1,e2e3=κ+34ge2,e3e1ge1,e3e2+κ14ge1,ϕe3ϕe2ge2,ϕe3ϕe1+2ge1,ϕe2ϕe3+ηe1ηe3e2ηe2ηe3e1+ge1,e3ηe2ξge2,e3ηe1ξ,

for all vector fields e1, e2, e3 on K̄.

K is assumed to be a submanifold of an almost contact metric manifold K̄ with the induced metric g. The Riemannian connection ̄ of K̄ induces canonically the connections ∇ and ∇ on the tangent bundle TK and the normal bundle TK of K respectively, and then the Gauss and Weingarten formulas are governed by

̄e1e2=e1e2+σe1,e2,
̄e1v=Ave1+e1v,

for each e1, e2TK and vTK, where σ and Av are the second fundamental form and the shape operator, respectively, for the immersion of K into K̄; they are related as

gσe1,e2,v=gAve1,e2,

where g is the Riemannian metric on K̄ and the induced metric on K.

If Te1 and Ne1 represent the tangential and normal part of ϕe1, respectively, for any e1TK, we can write

ϕe1=Te1+Ne1.

Similarly, for any vTK, we write

ϕv=tv+nv,

where tv and nv are the tangential and normal parts of ϕv, respectively. Thus, T (resp. N) is 1-1 tensor field on TK (resp. TK) and t (resp. n) is a tangential (resp. normal) valued 1-form on TK (resp. TK).

The notion of slant submanifolds in contact geometry was first defined by A. Lotta . Later, these submanifolds were studied by Cabrerizo et al. [9]. Now, we have the following definition of slant submanifolds:

Definition

A submanifold K of an almost contact metric manifold K̄ is said to be slant submanifold if for any xK and XTxK − ⟨ξ⟩, where ⟨ξ⟩ is the distribution spanned by the vector field ξ, the angle between X and ϕX is constant. The constant angle α ∈ [0, π/2] is then called the slant angle of K in K̄. If α = 0, the submanifold is invariant submanifold, and if α = π/2, then it is an anti-invariant submanifold. If α ≠ 0, π/2, it is a proper slant submanifold.

Moreover, Cabrerizo et al. [9] proved the characterizing equation for the slant submanifold. More precisely, they proved that a submanifold Nm is said to be a slant submanifold if a constant τ ∈ [0, 1] and a (1, 1) tensor field T, which satisfies the following relation:

T2=τIηξ,

where τ = − cos2α.

From (2.10), it is easy to conclude the following:

gTe1,Te2=cos2αge1,e2ηe1ηe2,e1,e2K.

Now, we define the bi-slant submanifold, which was introduced by Cabrerizo et al. .

A submanifold K of an almost contact metric manifold K̄ is said to be bi-slant submanifold if there exist two orthogonal complementary distributions Sα1 and Sα2 such that.

1) TK=Sα1Sα2ξ.

2) The distribution Sα1 is slant with the slant angle α1 ≠ 0, π/2.

3) The distribution Sα2 is slant with the slant angle α2 ≠ 0, π/2.

If α1 = 0 and α2 = π/2, then the bi-slant submanifold is a semi-invariant submanifold. Now, we have the following example of a bi-slant submanifold:

Example.

Considering the 5-dimensional submanifold in R9 with the usual Sasakian structure, such that

xū,v̄,w̄,s̄,t̄=2ū,0,w̄,0,v̄cosα1,v̄sinα1,s̄cosα2,s̄sinα2,t̄

for any α1, α2 ∈ (0, π/2), then it is easy to see that this is an example of a bi-slant submanifold M in R9 with slant angles α1 and α2. Moreover, it can be observed that

e1=2x1+y1z,e2=2cosα1y1+2sinα1y2,e3=2x3+y3z,
e4=2cosα2y3+2sinα2y4,e5=2z=ξ,

form a local orthonormal frame of TK, in which Sα1=span{e1,e2} and Sα2=span{e3,e4}, where Sα1 and Sα2 are the slant distributions with slant angles α1 and α2, respectively.

It is assumed that Kd=2p+2q+1 is a bi-slant submanifold of dimension d in which 2p and 2q are the dimensions of the slant distributions Sα1 and Sα2 respectively. Moreover, let {u1, u2, , u2p, u2p+1 = v1, u2p+2 = v2, , ud−1 = v2q, ud = v2q+1 = ξ} be an orthonormal frame of vectors which form a basis for the submanifold K2p+2q+1, such that {u1, u2 = sec α1Tu1, u3, u4 = sec α1Tu3, , u2p = sec α1Tu2p−1} is tangential to the distribution Sα1, and the set {v1, v2 = sec α2Tv1, v3, v4 = sec α2Tv3, … v2q = sec α2Tv2q−1} is tangential to Sα2. By Eq. 2.4, the curvature tensor R̄ for the bi-slant submanifold N2p+2q+1 is given by the formula:

R̄ui,uj,ui,uj=κ+14d2d+κ143i,j=1dg2ϕui,uj2d1.

The dimension of the bi-slant submanifold Kd can be decomposed as d = 2p + 2q + 1; then, using the formula (2.10) for slant distributions, we have

g2ϕui,ui+1=cos2α1,fori1,,2p1

and

g2ϕui,ui+1=cos2α2,fori2p+1,,2q1.

Then

i,j=1dg2ϕui,uj=2pcos2α1+2qcos2α2.

The relation (2.12) implies that

R̄ui,uj,ui,uj=κ+14d2d+κ146pcos2α1+6qcos2α22d1.

From the relation (2.13) and Gauss equation we have

κ+34dd1+κ146pcos2α1+6qcos2α22d1=2τn2H2+σ2

or

2τ=n2H2σ2+κ+34dd1+κ146pcos2α1+6qcos2α22d1.

In the study [1], Ali et al. studied the effect of conformal transformation on the curvature and second fundamental form. More precisely, it is assumed that K̄2t+1 together with a conformal metric g=e2ρḡ,, where ρC(K̄). Then, Ω̄a=eρΩa stands for the dual coframe of (K̄,ḡ) and ēa=eρea represents the orthogonal frame of (K̄,ḡ). Moreover, we have

Ω̄ab=Ωab+ρaΩbρbΩa,

where ρa is the component of the covariant derivative of ρ along the vector ea, that is, = aρaea.

e2ρR̄pqrs=Rpqrsρprδqs+ρqsδprρpsδqrρqrδps+ρpρrδqs+ρqρsδprρqρtδpsρpρsδqr|ψ|2δprδqsδilδqr..

Applying the pullback property in (2.15) to Km via the point x, we get

σ̄pqψ=eρσpqψρψδqp,
H̄ψ=eψHψρψ,

where σ̄pqψ and H̄ψ are the components of the second fundamental form and mean curvature vector.

The following significant relation was proved in [1].

e2ρσ̄2dH̄2+dH2=σ2.

3 Main Results

Initially, some basic results and formulas will be discussed which are compatible with the studies ([1, 22]).

It is well-known that a simply connected Sasakian space form K̄2t+1 is a (2t + 1)-sphere S2t+1 and Euclidean space R2t+1 with constant sectional curvature κ = 1 and κ = −3, respectively.

Now, we have the following result, which is based on the preceding arguments:

Lemma 3.1. [1] Let Kd be a slant submanifold of a Sasakian space form K̄2t+1(κ) which is closed and oriented with dimension 2. If f:KdK̄2t+1(κ) is embedding from Kd to K̄2t+1(κ), then there is a standard conformal map x:K̄2t+1(κ)S2t+1(1)R2t+2 such that the embedding Ω = x°f = (Ω1, , Ω2t+2) satisfies

Kd|Ωa|ψ2ΩadVK=0,a=1,,2t+1,

for ψ > 1.Remark: The Lemma 3.1 is also true for the bi-slant submanifolds and can be proved on the same lines as derived in [1].In the next result, we obtain a result which is analogous to Lemma 2.7 of [22]. Indeed, in Lemma 3.1 by the application of test function, we obtain the higher bound for λ1,ψ in terms of conformal function.

Proposition 3.2. Let Kd be a ddimensional bi-slant submanifold which is closed orientable isometrically immersed in a Sasakian space form K̄2t+1(κ). Then we have

λ1,ψVolKd2|1ψ2|t+1|1ψ2|dψ2Kde2ρψ2dV,

where x is the conformal map used in Lemma 3.1, and ψ > 1. The standard metric is identified by Lc,, and we consider x*L1 = e2pLc.Proof: Considering Ωa as a test function, along with Lemma 3.1, we have

λ1,ψKd|Ωa|ψ|Ωa|ψdV,1a2t+1.

Observing that a=12t+2|Ωa|2=1 and then |Ωa| ≤ 1, we get

a=12t+2|Ωa|2=i=1d|eiΩ|2=de2ρ.

On using 1 < ψ ≤ 2, we conclude

|Ωa|2|Ωa|ψ.

By the application of Holder’s inequality together with (3.2).–.(3.4), we get

λ1,ψVolKd=λ1,ψa=12t+2Kd|Ωa|2dVλ1,ψa=12t+2Kd|Ωa|ψdVλ1,ψKda=12t+2|Ωa|ψdV2t+21ψ/2Kda=1d|Ωa|2ψ/2dV=21ψ2t+11ψ2Kdde2ρψ2dV,

which is (3.1). On the other hand, if we assume ψ ≥ 2, then by Holder inequality

I=a=12t+2|Ωa|22t+212ψa=12t+2|Ωa|ψ2ψ.

As a result, we get

λ1,ψVolKd2t+2ψ21a=12t+2λ1,ψKd|Ωa|ψdV.

The Minkowski inequality provides

a=12t+2|Ωa|ψa=12t+2|Ωa|2ψ2=de2ρψ2.

By the application of 3.2, 3.7, and .3.8, it is easy to get (3.1).In the next theorem, we are going to provide a sharp estimate for the first eigenvalue of the ψ − Laplace operator on the bi-slant submanifold of the Sasakian space form K̄2t+1(κ).

Theorem 3.3. Let Kd be a ddimensional bi-slant submanifold of a Sasakian space form K̄2t+1(κ), then1. The first nonnull eigenvalue λ1,ψ of the ψLaplacian satisfies

λ1,ψ21ψ2t+11ψ2dψ2VolKψ/2×Kdκ+34+κ146pcos2α1+6qcos2α2dd12d+H2ψ/2dV

for 1 < ψ ≤ 2 and

λ1,ψ21ψ2t+11ψ2dψ2VolKψ/2×Kdκ+34+κ146pcos2α1+6qcos2α2dd12d+H2ψ/2dV

for 2<ψd2+1, where 2p and 2q are the dimensions of the invariant and slant distributions, respectively.2. The equality is satisfied in (3.9) and (3.10) if ψ = 2 and Kd are minimally immersed in a geodesic sphere of radius rκ of K̄2t+1(κ) with the following relations

r0=dλ1Δ1/2,r1=sin1r0,r1=sinh1r0.

Proof 1<ψ2ψ21. Proposition 3.2, together with Holder inequality, provides

λ1,ψVolKd21ψ2t+11ψ2mψ2Kde2ρψ2dV21ψ2t+1|1ψ2|dψ2VolKd1ψ2Kde2ρdVψ2.

We can calculate e2ρ with the help of conformal relations and the Gauss equation. Let K̄2k+1=K̄2k+1(κ), ḡ=e2ρLκ, and ḡ=κ*L1. From (2.14), the Gauss equation for the embedding f and the bi-slant embedding Ω = xf, we have

R=κ+34dd1+κ146pcos2α1+6qcos2α22d1+dd1H2+dH2Sσ2.
R̄dd1=dd1H̄2+dH̄2σ̄2.

On tracing (2.16), we have

e2ρR̄=Rd2d1|ρ|22d1Δρ.

Using 3.12, 3.13, and 3.14, we get

e2ρdd1+dd1H̄2+dH̄2σ̄2=κ+34dd1+κ146pcos2α1+6qcos2α22d1+dd1H2+dH2σ2d2d1ρ22d1Δρ.

The abovementioned relation implies that

e2ρσ̄2d2d1|ρ|22d1Δρ=dd1e2ρκ+34κ146pcos2α1+6qcos2α2dd12d+e2ρH̄2H2+de2ρH̄2H2.

From 2.18, 2.19, we derive

dd1e2ρκ+34κ146pcos2α1+6qcos2α2dd12d+dd1ψHψρψ2=dd1H2d2d1|ρ|22d1Δρ.

Furthermore, on simplification, we get

e2ρ=κ+34+κ146pcos2α1+6qcos2α2dd1+2dH22dΔρd2d|Δρ|2ρH2..

On integrating along dV, it is easy to see that

λ1,ψVolKd2|1ψ2|t+1|1ψ2|dψ2VolKd1ψ2Kde2ρdVψ2.2|1ψ2|t+1|1ψ2|dψ2VolKdψ21Kdκ+34+κ146pcos2α1+6qcos2α2dd12d+H2dVψ/2.,

which is equivalent to (3.9). If ψ > 2, then it is not possible to apply Holder inequality to govern Kd(e2ρdV)ψ2 by using Kd(e2ρ). Now, multiplying both sides of Eq. 3.18 by e(ψ−2)ρ and integrating on Kd,

KdeψρdVKdκ+34+κ146pcos2α1+6qcos2α2dd12d+H2eψ2ρdVd22ψ+4dKdeψ2|Δρ|2dVKdκ+34+κ146pcos2α1+6qcos2α2dd12d+H2eψ2ρdV.

From the assumption, it is evident that d ≥ 2ψ − 2. On applying Young’s inequality, we arrive at

Kdκ+34+κ146pcos2α1+6qcos2α2dd12d+H2eψ2ρdV2ψKd|κ+34+κ146pcos2α1+6qcos2α2dd12d+H2|ψ/2dV+ψ2ψKdeψρdV.

From Eqs 3.20, 3.21, we conclude the following:

KdeψρdVKd|κ+34+κ146pcos2α1+6qcos2α2dd12d+H2|ψ/2dV.

Substituting (3.22) in (3.1), we obtain (3.10). For the bi-slant submanifolds, the equality case holds true in (3.9), and the equality cases of (3.2) and 3.4 imply that

|Ωa|2=|Ωa|ψ,
ΔψΩa=λ1,ψ|Ωa|ψ2Ωa,

for a = 1, , 2t + 2. For 1 < ψ < 2, we have |Ωa| = 0 or 1. Therefore, there exists only one a for which |Ωa| = 1 and λ1,ψ = 0, which is not possible since the eigenvalue λi,ψ ≠ 0. This leads to using the value of ψ equal to 2, so we can apply Theorem 1.5 of [15].For ψ > 2, the equality in (3.10) still holds; this indicates that equalities in (3.7) and (3.8) are satisfied, and this leads to

|Ω1|ψ==|Ω2t+2|ψ,

and there exists a such that |∇Ωa| = 0. It shows that Ωa is a constant and λ1,ψ = 0; this again contradicts the fact that λ1,ψ ≠ 0, which completes the proof.Note 3.1 If ψ = 2, then the ψ − Laplacian operator becomes the Laplacian operator. Therefore, we have the following corollary.

Corollary 3.4. Let Kd be a ddimensional bi-slant submanifold of a Sasakian space form K̄2t+1(κ), then the first nonnull eigenvalue λ1Δ of the Laplacian satisfies

λ1ΔdVolKKdκ+34+κ146pcos2α1+6qcos2α2dd12d+H2dV.

By the application of Theorem 3.3 for 1 < ψ ≤ 2, we have the following result.

Theorem 3.5. Let Kd be a ddimensional bi-slant submanifold of a Sasakian space form K̄2t+1(κ), then the first nonnull eigenvalue λ1,ψ of the ψLaplacian satisfies

λ1,ψ21ψ2t+11ψ2mψ2VolKψ/2×Kdκ+34+κ146pcos2α1+6qcos2α2dd12d+H2ψ2ψ1dVψ1

for 1 < ψ ≤ 2.Proof: If 1 < ψ ≤ 2, we have ψ2(ψ1)1, and then the Holder inequality provides

Kdκ+34+κ146pcos2α1+6qcos2α2dd12d+H2dVVolKd12ψ1ψ×Kdκ+34+κ146pcos2α1+6qcos2α2dd12d+H2ψ2ψ12ψ1ψ

On combining (3.9) and (3.25), we get the required inequality. This completes the proof.Note 3.2 If κ = 1, then simply the connected Sasakian space form M̄2t+1(κ) becomes an odd dimensional sphere, B2t+1(1). Furthermore, if κ = −3, then M̄2t+1(κ) changes to (2t + 1) − dimensional Euclidean space.As a result of the abovementioned arguments, we concludeCorollary 3.6 Let Kd be a d − dimensional bi-slant submanifold of a Sasakian space form B2t+1(1) (odd dimensional sphere), then1. The first nonnull eigenvalue λ1,ψ of the ψLaplacian satisfies

λ1,ψ21ψ2t+11ψ2mψ2VolKψ/2×Kd1+H2dVψ/2

for 1 < ψ ≤ 2 and

λ1,ψ21ψ2t+11ψ2dψ2VolKψ/2×Kd1+H2dVψ/2

for 2<ψd2+1, where 2p and 2q are the dimensions of the anti-invariant and slant distributions, respectively.Note 3.3 If α1 = 0 and α2 = π/2, then the bi-slant submanifolds become the semi-invariant submanifolds.With the application of the abovementioned findings, we can deduce the following results for semi-invariant submanifolds in the setting of Sasakian manifolds.Corollary 3.7 Let Kd be a d − dimensional semi-invariant submanifold of a Sasakian space form K̄2t+1(κ), then1. The first nonnull eigenvalue λ1,ψ of the ψLaplacian satisfies

λ1,ψ21ψ2t+11ψ2dψ2VolKψ/2×Kdκ+34+3pc12dd112d+H2dVψ/2

for 1 < ψ ≤ 2 and

λ1,ψ21ψ2t+11ψ2dψ2VolKψ/2×Kdκ+34+3pc12dd112d+H2dVψ/2

for 2<ψd2+1, where 2p and 2q are the dimensions of the anti-invariant and slant distributions, respectively.2. The equality is satisfied in (3.28) and (3.29) if ψ = 2 and Kd are minimally immersed in a geodesic sphere of radius rc of K̄2t+1(κ) with the following relation

r0=dλ1Δ1/2,r1=sin1r0,r1=sinh1r0.

Furthermore, by Corollary 3.4 and Note 3.1, we deduce the following.Corollary 3.8 Let Kd be a d − dimensional semi-invariant submanifold of a Sasakian space form K̄2t+1(κ), then the first nonnull eigenvalue λ1Δ of the Laplacian satisfies

λ1ΔdVolKKdκ+34+3pκ12dd112d+H2dV.

In addition, we also have the following corollary, which can be derived from Theorem 3.5.Corollary 3.9 Let Kd be a d − dimensional semi-invariant submanifold of a Sasakian space form K̄2t+1(κ), then the first nonnull eigenvalue λ1,ψ of the ψ − Laplacian satisfies

λ1,ψ21ψ2t+11ψ2dψ2VolKψ/2×Kdκ+34+3pκ12sd112d+H2ψ2ψ1dVψ1,

for 1 < ψ ≤ 2.

Data Availability Statement

The original contributions presented in the study are included in the article/Supplementary Material, further inquiries can be directed to the corresponding author.

Author Contributions

All the authors listed have made a substantial, direct, and intellectual contribution to the work and approved it for publication.

Funding

The first author extends his appreciation to the Deanship of Scientific Research at King Khalid University for funding this work through research groups program under grant number R.G.P.1/206/42.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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Keywords: eigenvalues, Laplacian, bi-slant submanifolds, Sasakian space form, Reilly-like inequalities

Citation: Alkhaldi AH, Khan MA, Aquib M and Alqahtani LS (2022) Estimation of Eigenvalues for the ψ-Laplace Operator on Bi-Slant Submanifolds of Sasakian Space Forms. Front. Phys. 10:870119. doi: 10.3389/fphy.2022.870119

Received: 05 February 2022; Accepted: 10 March 2022;
Published: 18 May 2022.

Edited by:

Josef Mikes, Palacký University, Czechia

Reviewed by:

Anouar Ben Mabrouk, University of Kairouan, Tunisia
Aligadzhi Rustanov, Moscow State Pedagogical University, Russia

Copyright © 2022 Alkhaldi, Khan, Aquib and Alqahtani. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Ali H. Alkhaldi, ahalkhaldi@kku.edu.sa; Meraj Ali Khan, meraj79@gmail.com

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