stellar mass is a constraint for the formation scenarios.'
date: 'Accepted 2019 January 21. Received 2019 January 21; in original form 2018 December 13'
title: 'The [*HST*]{} Large Programme on NGC6752. II. Multiple populations at the bottom of the main sequence probed in NIR [^1] '
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Introduction {#sec:intro}
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Near-infrared Wide Field Camera 3 (WFC3/NIR) observations have proved very effective in separating and characterizing multiple populations of faint M-dwarfs in NGC2808, NGC6121 (M4) and $\omega$Centauri (Milone et al.2012a, 2014, 2017a).

This work is based on deep [*HST*]{} images of the nearby globular cluster (GC) NGC6752 collected as part of the [*Hubble-Space-Telescope*]{} ([*HST*]{}) program GO-15096 (PI.L.R.Bedin). The main target of the project is the white-dwarf cooling sequence of NGC6752, which is the subject of separate work by Bedin et al.(in preparation, see also Bedin et al.2008, 2009, 2010, 2015). In this paper, we exploit parallel WFC3/NIR observations only to investigate, for the first time, the multiple populations of NGC6752 at the bottom of the main sequence (MS).

NGC6752 is one of the most-studied GCs in the context of multiple stellar populations. Optical and Ultraviolet observations, mostly from [*HST*]{}, revealed that its color-magnitude diagram (CMD) hosts three distinct red-giant branches 