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The integrated shear 3-point correlation function $\zeta_{\pm}$ measures the correlation between the local shear 2-point function $\xi_{\pm}$ and the 1-point shear aperture mass in patches of the sky. Unlike other higher-order statistics, $\zeta_{\pm}$ can be efficiently measured from cosmic shear data, and it admits accurate theory predictions on a wide range of scales as a function of cosmological and baryonic feedback parameters. Here, we develop and test a likelihood analysis pipeline for cosmological constraints using $\zeta_{\pm}$. We incorporate treatment of systematic effects from photometric redshift uncertainties, shear calibration bias and galaxy intrinsic alignments. We also develop an accurate neural-network emulator for fast theory predictions in MCMC parameter inference analyses. We test our pipeline using realistic cosmic shear maps based on $N$-body simulations with a DES Y3-like footprint, mask and source tomographic bins, finding unbiased parameter constraints. Relative to $\xi_{\pm}$-only, adding $\zeta_{\pm}$ can lead to $\approx 10-25\%$ improvements on the constraints of parameters like $A_s$ (or $\sigma_8$) and $w_0$. We find no evidence in $\xi_{\pm} + \zeta_{\pm}$ constraints of a significant mitigation of the impact of systematics. We also investigate the impact of the size of the apertures where $\zeta_{\pm}$ is measured, and of the strategy to estimate the covariance matrix ($N$-body vs. lognormal). Our analysis solidifies the strong potential of the $\zeta_{\pm}$ statistic and puts forward a pipeline that can be readily used to improve cosmological constraints using real cosmic shear data., Comment: 21 pages, 11 figures, 3 tables. Comments welcome

Accurate knowledge of the redshift distributions of faint samples of galaxies selected by broad-band photometry is a prerequisite for future weak lensing experiments to deliver precision tests of our cosmological model. The most direct way to measure these redshift distributions is spectroscopic follow-up of representative galaxies. For this to be efficient and accurate, targets have to be selected such that they systematically cover a space defined by apparent colours in which there is little variation in redshift at any point. 4C3R2 will follow this strategy to observe over 100 000 galaxies selected by their KiDS-VIKING ugriZYJHKs photometry over a footprint identical to that of the WAVES survey, to constrain the colour-redshift relation with high multiplicity across two-thirds of the colour space of future Euclid and Rubin samples., Published in The Messenger vol. 190, pp. 28-30, March 2023.