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We report three new barium (Ba) dwarfs lying in Sirius-like systems, whichprovides direct evidence that Ba dwarfs are companions to white dwarfs (WDs).Atmospheric parameters, stellar masses, and chemical abundances of 25 elements,including light, $\alpha$, Fe-peak and s-process elements, are derived fromhigh resolution and high S/N spectra. Enhancement of s-process elements with[s/Fe] ratios between 0.4 and 0.6 confirm them as mild barium stars. Theestimated metallicities ($-$0.31, $-$0.06, 0.13) of BD+68$^\circ$1027,RE~J0702+129 and BD+80$^\circ$670 are in the range of known Ba dwarfs andgiants. As expected, observed indices of [hs/ls], [s/Fe] and [C/Fe] showanticorrelation with metallicity. AGB progenitor masses are estimated for theWD companions of RE~J0702+129 (1.47 $M_{\odot}$) and BD+80$^\circ$670 (3.59$M_{\odot}$), which confirms the predicted range of progenitor AGB masses (1.5$\sim$ 4 $M_{\odot}$) for unseen WDs around Ba dwarfs.  Surface abundances of s-process elements in RE~J0702+129 and BD+80$^\circ$670are compared with AGB models and they are in close agreement, within predictedaccretion efficiencies and pollution factors for Ba stars. These resultssupport that the origin of s-process overabundances in Ba dwarfs is similar toBa giants via McClure hypothesis in which Ba stars accumulate s-processelements through mass transfer from their host companions during AGB phase.

Three new barium dwarfs with WD companions: BD+68 1027, RE J0702+129 and BD+80 670