In this paper, we refined the local limit theorem for sums of independent integer-valued random variables under the assumption of a finite $ (2+\delta) $-moment, where $ 0 < \delta < 1 $. This class includes sums of discrete Pareto random variables, which arise naturally in various applications. Moreover, Kammoo et al. (2023) established a local limit theorem in this setting with an explicit error bound. However, the associated constants become excessively large as $ \delta \to 0 $. By combining the method of Siripraparat and Neammanee (2021) with a non-integer-order Taylor expansion, we obtained substantially sharper constants in the corresponding error bound.
Citation: Jirapat Trakankitnukul, Kritsana Neammanee, Tatpon Siripraparat. The improvement of local limit theorem without assuming finite third moment[J]. AIMS Mathematics, 2026, 11(8): 25123-25139. doi: 10.3934/math.20261010
In this paper, we refined the local limit theorem for sums of independent integer-valued random variables under the assumption of a finite $ (2+\delta) $-moment, where $ 0 < \delta < 1 $. This class includes sums of discrete Pareto random variables, which arise naturally in various applications. Moreover, Kammoo et al. (2023) established a local limit theorem in this setting with an explicit error bound. However, the associated constants become excessively large as $ \delta \to 0 $. By combining the method of Siripraparat and Neammanee (2021) with a non-integer-order Taylor expansion, we obtained substantially sharper constants in the corresponding error bound.
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