Let $\mathfrak{L}=-\triangle+V$ be a Schr\"{o}dinger operator on $\mathbb{R}^{n}(n>3), $ where $\triangle$ is the Laplacian on $\mathbb{R}^{n}$ and $V\neq 0$ is a nonnegative locally integrable function. The problems about the Schr\"{o}dinger operators $\mathfrak{L}$ have been well studied(see [1-3] for example). Especially, Fefferman [1], Shen [2] and Zhong [3] developed some basic results.
The commutators generated by the Riesz transforms associated with the Schrödinger operators and BMO functions or Lipschitz functions also attract much attention(see[4-6] for example). Chu [7], consider the boundedness of commutators generalized by the $\rm{BM}{{\rm{O}}_{\mathfrak{L}}}$ functions and the Riesz transform $\nabla(-\triangle+V)^{-1/2}$ on Lebesgue spaces. Mo et al. [8] established the boundedness of commutators generated by the Campanato-type functions and the Riesz transforms associated with Schrödinger operators.
First, let us introduce some notations. A nonnegative locally $L^{q}(\mathbb{R}^{n})$ integrable function $V$ is said to belong to $B_{q}(1<q<\infty)$ if there exists $C=C(q, V)>0$ such that the reverse Hölder's inequality
holds for every ball $B$ in $\mathbb{R}^{n}$.
Let $T_{j, 1}=\nabla(-\triangle+V)^{-1/2}$ or $T_{j, 1}=\pm I$ and $\mathrm{T}_{j, 2}$ be a linear operator which is bounded on $\mathrm{L} ^{p}(\mathbb{R}^{n})$ space, for $j=1, 2, \dots, m$. Let $M_{b}f=bf$, where $b$ is a locally integrable function on $\mathbb{R}^{n}$, then the Toeplitz operator is defined by
About the Toeplitz operator, there are some results. Mo et al. [9] established the boundedness of the Toeplitz operator generalized by the singular integral operator with nonsmooth kernel and the generalized fractional. Liu et al. [11] investigated the boundness of the Toeplitz operator related to the generalized fractional integral operator.
The commutator $[b, T](f)=bT(f)-T(bf)$ is a particular case of the Toeplitz operators. Inspired by [7-10], we will consider the boundedness of the Toeplitz operators generated by the Campanato-type functions and Riesz transforms associated with Schödinger operators.
Definition 1.1 Let $f\in L_{loc}(\mathbb{R}^{n})$, then the sharp maximal function associated with $\mathfrak{L}=-\triangle+V$ is defined by
Where $\rho$ is define by
Definition 1.2 [12, 13] Let $\mathfrak{L}=-\triangle+V$, $p\in(0, \infty)$ and $\beta\in\mathbb{R}$. A function $f\in L_{loc}^{p}(\mathbb{R}^{n})$ is said to be in $\Lambda_{\mathfrak{L}}^{\beta, p}(\mathbb{R}^{n})$, if there exists a nonnegative constant $C$ such that for all $x\in\mathbb{R}^{n}$ and $0<s<\rho(x)\leq r, $
where $f_{B}=\frac{1}{|B|}\int_{B}f(y)dy$ for any ball $B.$ Moreover, the minimal constant $C$ as above is defined for the norm of $f$ in the space $\Lambda_{\mathfrak{L}}^{\beta, p}(\mathbb{R}^{n})$ and denote by $\|f\|_{\Lambda_{\mathfrak{L}}^{\beta, p}(\mathbb{R}^{n})}.$
Remak 1.1 [12] When $p\in[1, \infty), $ $\Lambda_{\mathfrak{L}}^{0, p}(\mathbb{R}^{n})=BMO_{\mathfrak{L}}(\mathbb{R}^{n}).$ And, when $0\leq\beta<\infty$ and $p_1, p_2\in[1, \infty)$, $\Lambda_{\mathfrak{L}}^{\beta, p_1}(\mathbb{R}^{n})=\Lambda_{\mathfrak{L}}^{\beta, p_2}(\mathbb{R}^{n})$ and $\|f\|_{\Lambda_{\mathfrak{L}}^{\beta, p_1}(\mathbb{R}^{n})}\sim\|f\|_{\Lambda_{\mathfrak{L}}^{\beta, p_2}(\mathbb{R}^{n})}.$ For simplicity, we denote $\Lambda_{\mathfrak{L}}^{\beta, p}(\mathbb{R}^{n})$ by $\Lambda_{\mathfrak{L}}^{\beta}(\mathbb{R}^{n}).$
Lemma 1.1 (see [2, 7]) Suppose that $V\in B_q (n/2\leq q<n)$ satisfies the condition
then the kernel $K(x, y)$ of operator $\nabla(-\triangle+V)^{-1/2}$ satisfies the following estimates: there exists a constant $\delta>0$ such that for any nonnegative integrate $i, $
for $0<|h|<\frac{|x-y|}{2}.$
Hence, $\nabla(-\triangle+V)^{-1/2}$ is boundedness on $ L^{p}(\mathbb R^n)$ space for $1<p\leq p_{0}, $ where $1/p_{0}=1/q-1/n.$
Throughout this paper, the letter C always remains to denote a positive constant that may vary at each occurrence but is independent of the essential variable.
Theorems 2.1 Let $V\in B_q$ satisfy (1.2) for $n/2\leq q<n$. Let $0\leq\beta<1, $ $b\in\Lambda_{\mathfrak{L}}^{\beta}(\mathbb{R}^{n})$, $1<\tau<\infty$ and $1<s<p_{0}$, where $1/p_{0}=1/q-1/n.$ Suppose that $\Theta^{1}f=0$ for any $f\in L^{r}(\mathbb{R}^n)$ $(1<r<\infty), $ then there exists a constant $C>0$ such that
Theorems 2.2 Let $V\in B_q$ satisfy(1.2) for $n/2\leq q<n$ and $1<p_0<\infty$ satisfy $1/p_{0}=1/q-1/n.$ Suppose that $\Theta^{1}f=0$ for any $f\in L^{\tau}(\mathbb{R}^n)$ $(1<\tau<\infty), $ $0<\beta<1, $ and $b\in\Lambda_{\mathfrak{L}}^{\beta}(\mathbb{R}^{n})$. Then for $1<r<\min\{1/\beta, p_0\}$ and $1/p=1/r-\beta, $ there exists a constant $C>0$, such that
Theorems 2.3 Let $V\in B_q$ satisfy (1.2) for $n/2\leq q<n$ and $1<p_0<\infty$ satisfy $1/p_{0}=1/q-1/n.$ Suppose that $\Theta^{1}f=0$ for any $f\in L^{\tau}(\mathbb{R}^n)$ $(1<\tau<\infty)$ and $b\in BMO_{\mathfrak{L}}(\mathbb{R}^{n})$, then for $1<p<p_0, $ there exists a constant $C>0$, such that
To prove the theorems, we need the following lemmas.
Lemma 2.1 (see [7]) Let $0<p_0<\infty, $ $p_0\leq p<\infty$ and $\delta>0.$ If $f$ satisfies the condition $M(|f|^{\delta})^{1/\delta}\in L^{p_0}, $ then exists a constant $C>0$ such that
Lemma 2.2 (see [14]) For $1\leq\gamma<\infty$ and $\beta>0, $ let
Suppose that $\gamma<p<n/\beta$ and $1/q=1/p-\beta/n, $ then $\|M_{\gamma, \beta}(f)\|_{L^{q}}\leq C\|f\|_{L^{p}}.$
Remark 2.1 When $\beta=0$, we denote $M_{\gamma, \beta}=M_{r}.$ And, it is easy to see that $M_{r}$ is boundedness on $L^{p}(\mathbb{R}^{n}), $ for $1<r<p.$
Lemma 2.3 (see [8]) Let $B=B(x, r)$ and $0<r<\rho(x)$, then
Firstly, let us prove Theorem 2.1.
Fix a ball $B=B(x, r_0)$ and let $2B=B(x, 2r_0).$ We need only to estimate
Case Ⅰ When $0<r_0 <\rho(x), $ using the condition $\Theta^{1}f=0$, then we have
If $T_{j, 1}=\nabla(-\triangle+V)^{-1/2}, $ then
Let $\tau$ and $s$ be as in Theorem 2.1. Then using Hölder's inequality and the $L^{s}$ boundedness of $T_{j, 1}$(Lemma 1.1), we have
Let's estimate $I_{2}.$ From (1.4), it follows that
For $H_{1}, $ since $\delta >0, $ by Hölder's inequality, we have
From Lemma 2.3 and Hölder's inequality, it follows that
Thus
So when $T_{j, 1}=\nabla(-\triangle+V)^{-1/2}, $ we conclude that
If $T_{j, 1}=\pm I, $ it is obvious that
Thus using the above formula and Hölder's inequality, we conclude
Thus for $0<r_0 <\rho(x), $ we conclude that
Case Ⅱ When $r_0 >\rho(x), $ we have
If $T_{j, 1}=\nabla(-\triangle+V)^{-1/2}, $ then for $1<\tau<\infty$ and $1<s<p_{0}$ are as in Theorem 2.1, we have
Since, when $y\in 2B$ and $z\in 2^{k+1}B\backslash 2^kB, $ we have $|x-z|\sim|y-z|.$ Then, taking $s, \tau$ as above, we get
If $T_{j, 1}=\pm I, $ then by Hölder's inequality, we obtain
And
Thus for $r_0 >\rho(x), $
So whenever $0<r_0 <\rho(x)$ or $r_0 >\rho(x), $ we have
Now, let us turn to prove Theorem 2.2.
Let $s, \tau$ be as in Theorem 2.1 and satisfy $1<s\tau<p.$ Then applying Theorem 2.1, Lemma 2.1 and Lemma 2.2, we know that
Thus we complete the proof of Theorem 2.1-2.1.
It is obvious that $\Lambda_{\mathfrak{L}}^{0}=BMO_{\mathfrak{L}}.$ Thus from the proof of Theorem 2.1, we have
Since $M_{s\tau}$ is boundedness on $L^{p}(\mathbb{R}^{n}), $ then
Therefore, we complete the proof of Theorem 2.3.