arXiv subjects

Surjeet Singh Choudhary

Publications and source records attributed to Surjeet Singh Choudhary.

13 recordsLinked to original sources

arXiv2026

Sharp power-weight estimates for the fractional spherical maximal operator

For $0\leqα<n$, let $A_{*}^α$ denote the fractional spherical maximal operator. In this paper we characterise the range of $β$ for which the $L^p-L^q$ power-weight estimate \[\left\|A_{*}^α f\right\|_{L^q(|x|^{qβ})} \leq C \left\|f\right\|_{L^p(|x|^{pβ})}\] holds. In the diagonal case $p=q$, our work gives an affirmative answer to a conjecture of Lee. We prove analogous results for the lacunary fractional spherical maximal operator.

math.CA↗

arXiv2026

Lacunary $δ$-Discretised Spherical Maximal Operators

We study the lacunary analogue of the $δ$-discretised spherical maximal operators introduced by Hickman and Jančar, for $δ\in (0, 1/2)$, and establish the boundedness on $L^p$ for all $1 < p < \infty$, along with the endpoint weak-type estimate $H^1 \to L^{1,\infty}$. We also prove the corresponding $L^p$ boundedness for the multi-parameter variant. The constants in these bounds are uniform in $δ$, and thus, by taking the limit $δ\to 0^+$, our results recover the classical boundedness of the lacunary spherical maximal function.

math.CA↗

arXiv2026

On a variant of bilinear spherical maximal function

We obtain $L^p-$estimates for the full and lacunary maximal functions associated to the bilinear spherical averages given by \[\mathfrak{A}_t(f_1,f_2)(x,y)=\int_{\mathbb S^{2d-1}}f_1(x+tz_1,y)f_2(x,y+tz_2)\;dσ(z_1,z_2),\;t>0,\] for all dimensions $d\geq1$. We show that the estimates for such operators in dimensions $d\geq2$ essentially rely on the method of slicing. The bounds for the lacunary maximal function in dimension one are more delicate and require a trilinear smoothing inequality, which is based on an appropriate sublevel set estimate in this context.

math.CA↗

arXiv2026

Bilinear spherical maximal function with fractal dilations

In this paper, we investigate the $L^p-$boundedness of the bilinear spherical maximal function associated with a general set of dilations $E\subset\R_+$. We quantify the range of $L^p-$boundedness in terms of a dilation-invariant notion of the upper Minkowski dimension of the set $E$. A particular case of this study settles an open question of $L^p-$boundedness of the maximal lacunary bilinear spherical function in borderline cases $p_1=1$ or $p_2=1$ in dimension $d\geq4$.

math.CA↗

arXiv2026

Boundary estimates for the fractional spherical maximal function

In this article, we study the fractional spherical maximal function and its lacunary counterpart. We study the necessary and sufficient conditions for $L^p-L^q$ boundedness of both maximal functions. In particular, we prove the restricted weak type estimate for both full and lacunary fractional spherical maximal functions at the boundary of the maximal $L^p-L^q$ bounded regions.

math.AP↗

arXiv2026

A curved three-point pattern problem for fractal sets on the real line

We study the occurrence of curved three-point configurations in fractal subsets of the real line. We prove that if $E \subset [0,1]$ is a compact set with sufficiently large Hausdorff dimension, then $E$ contains a curved three-point progression associated with a broad class of nonlinear functions. Our approach can also show the existence of the curved three-point pattern under the assumption that the Hausdorff content of $E$ is bounded away from zero. The class of functions includes, in addition to polynomials with vanishing constant term, nonlinear functions such as \[ t^k \log(1+t), \quad \forall k \geq 1. \]

math.CA↗

arXiv2024

Sparse Bounds for Discrete Maximal Functions associated with Birch-Magyar averages

In this article, we study discrete maximal function associated with the Birch-Magyar averages over sparse sequences. We establish sparse domination principle for such operators. As a consequence, we obtain $\ell^p$-estimates for such discrete maximal function over sparse sequences for all $p>1$. The proof of sparse bounds is based on scale-free $\ell^p-$improving estimates for the single scale Birch-Magyar averages.

math.NT↗

arXiv2024

$L^{p}-$estimates for uncentered spherical averages and lacunary maximal functions

The primary goal of this paper is to introduce bilinear analogues of uncentered spherical averages, Nikodym averages associated with spheres and the associated bilinear maximal functions. We obtain $L^p$-estimates for uncentered bilinear maximal functions for dimensions $d\geq2$. Moreover, we also discuss the one-dimensional case. In the process of developing these results, we also establish new and interesting results in the linear case. In particular, we will prove $L^p$-improving properties for single scale averaging operators and $L^p$-estimates for lacunary maximal functions in this context.

math.CA↗

arXiv2024

Sharp endpoint $L^p-$estimates for Bilinear spherical maximal functions

In this article, we address endpoint issues for the bilinear spherical maximal functions. We obtain borderline restricted weak type estimates for the well studied bilinear spherical maximal function $$\mathfrak{M}(f,g)(x):=\sup_{t>0}\left|\int_{\mathbb S^{2d-1}}f(x-ty_1)g(x-ty_2)\;dσ(y_1,y_2)\right|,$$ in dimensions $d=1,2$ and as an application, we deduce sharp endpoint estimates for the multilinear spherical maximal function. We also prove $L^p-$estimates for the local spherical maximal function in all dimensions $d\geq 2$, thus improving the boundedness left open in the work of Jeong and Lee (https://doi.org/10.1016/j.jfa.2020.108629). We further study necessary conditions for the bilinear maximal function, \[\mathcal M (f,g)(x)=\sup_{t>0}\left|\int_{\mathbb S^{1}}f(x-ty)g(x+ty)\;dσ(y)\right|\] to be bounded from $L^{p_1}(\mathbb R^2)\times L^{p_2}(\mathbb R^2)$ to $L^p(\mathbb R^2)$ and prove sharp results for a linearized version of $\mathcal M$.

math.CA↗

arXiv2023

Bilinear Bochner-Riesz means for convex domains and Kakeya Maximal function

In this paper we introduce bilinear Bochner-Riesz means associated with convex domains in the plane $\mathbb R^2$ and study their $L^p-$boundedness properties for a wide range of exponents. One of the important aspects of our proof involves the use of bilinear Kakeya maximal function in the context of bilinear Bochner-Riesz problem. This amounts to establish suitable $L^p-$ estimates for the later. We also point out some natural connections between bilinear Kakeya maximal function and Lacey's bilinear maximal function.

math.CA↗

arXiv2023

Sparse bounds for maximal oscillatory rough singular integral operators

We prove sparse bounds for maximal oscillatory rough singular integral operator $$T^{P}_{Ω,*}f(x):=\sup_{ε>0} \left|\int_{|x-y|>ε}e^{ιP(x,y)}\frac{Ω\big((x-y)/|x-y|\big)}{|x-y|^{n}}f(y)dy\right|,$$ where $P(x,y)$ is a real-valued polynomial on $\mathbb{R}^{n}\times \mathbb{R}^{n}$ and $Ω\in L^{\infty}(\mathbb{S}^{n-1})$ is a homogeneous function of degree zero with $\int_{\mathbb{S}^{n-1}}Ω(θ)~dθ=0$. This allows us to conclude weighted $L^p-$estimates for the operator $T^{P}_{Ω,*}$. Moreover, the norm $\|T^P_{Ω,*}\|_{L^p\rightarrow L^p}$ depends only on the total degree of the polynomial $P(x,y)$, but not on the coefficients of $P(x,y)$. Finally, we will show that these techniques also apply to obtain sparse bounds for oscillatory rough singular integral operator $T^{P}_Ω$ for $Ω\in L^{q}(\mathbb{S}^{n-1})$, $1<q\leq\infty$.

math.CA↗

arXiv2022

Bilinear Bochner-Riesz square function and applications

In this paper we introduce Stein's square function associated with bilinear Bochner-Riesz means and investigate its $L^p$ boundedness properties. Further, we discuss several applications of the square function in the context of bilinear multipliers. In particular, we obtain results for maximal function associated with generalised bilinear Bochner-Riesz means. This extends the results proved in~\cite{JS}. Another application concerns the $L^p$ estimates for bilinear fractional Schrödinger multipliers. Finally, we improve upon a result of Grafakos, He and Honzik~\cite{GHH} in the context of bilinear radial multipliers and provide a dimension free sufficient condition on the bilinear multipliers for $L^2\times L^2\rightarrow L^1$ boundedness of the associated maximal function. The generalised bilinear spherical maximal function is a particular example of such maximal functions.

math.CA↗

arXiv2022

On the bilinear Bochner-Riesz problem at critical index

In this paper we study maximal and square functions associated with bilinear Bochner-Riesz means at the critical index. In particular, we prove that they satisfy weighted estimates from $L^{p_1}(w_1)\times L^{p_2}(w_2)\rightarrow L^p(v_w)$ for bilinear weights $(w_1,w_2)\in A_{\vec{P}}$ where $p_1,p_2>1$ and $\frac{1}{p_1}+\frac{1}{p_2}=\frac{1}{p}$. Also, we show that both the operators fail to satisfy weak-type estimates at the end-point $(1,1,\frac{1}{2})$.

math.CA↗