Context : Subdwarf B stars ( sdBs ) play a crucial role in stellar evolution , asteroseismology , and far-UV radiation of early-type galaxies , and have been intensively studied with observation and theory .
It has theoretically been predicted that sdBs with neutron star ( NS ) companions exist in the Galaxy , but none have been discovered yet .
This remains a puzzle in this field .
In a previous study ( hereafter Paper I ) , we have studied the formation channels of sdB+NS binaries from main-sequence ( MS ) stars plus NS binaries by establishing a model grid , but it is still unclear how these binaries consisting of MS stars and NS binaries came to be in the first place .

Aims : We systematically study the formation of sdB+NS binaries from their original zero-age main-sequence progenitors .
We bridge the gap left by our previous study in this way .
We obtain the statistical population properties of sdB+NS binaries and provide some guidance for observational efforts .

Methods : We first used Hurley ’ s rapid binary evolution code BSE to evolve 10 ^ { 7 } primordial binaries to the point where the companions of NS+MS , NS+Hertzsprung gap ( HG ) star , and NS+Giant Branch ( GB ) star binaries have just filled their Roche lobes .
Next , we injected these binaries into the model grid we developed in Paper I to obtain the properties of the sdB+NS populations .
We adopted two prescriptions of NS natal kicks : the classical Maxwellian distribution with a dispersion of \mathrm { \sigma = 265 kms ^ { -1 } } , and a linear formula that assumes that the kick velocity is associated with the ratio of ejected to remnant mass .
Different values of \alpha _ { CE } , where \alpha _ { CE } is the common-envelope ejection efficiency , were chosen to examine the effect of common-envelope evolution on the results .

Results : In the Galaxy , the birthrate of sdB+NS binaries is about 10 ^ { -4 } \mathrm { yr ^ { -1 } } and there are \sim 7000 - 21000 such binaries .
This contributes 0.3-0.5 % of all sdB binaries in the most favorable case .
Most Galactic sdB+NS binaries ( \gtrsim 60 \% ) arise from the channel of stable mass transfer .
The value of \alpha _ { CE } has little effect on the results , but when we use the linear formula prescription of NS natal kick , the number and birthrate doubles in comparison to the results we obtained with the Maxwellian distribution .
The orbital periods of sdB+NS binaries from different formation channels differ significantly , as expected .
This results in two peaks in the radial velocity ( RV ) semi-amplitude distribution : 100 - 150 { { kms ^ { -1 } } } for stable mass transfer , and 400 - 600 { { kms ^ { -1 } } } for common-envelope ejection .
However , the two sdB+NS binary populations exhibit similar delay-time distributions , which both peak at about 0.2Gyr .
This indicates that Galactic sdB+NS binaries are born in very young populations , probably in the Galactic disk .
The sdB+NS binaries produced from the common-envelope ejection channel are potential sources of strong gravitational wave radiation ( GWR ) , and about \sim 100 - 300 could be detected by the Laser Interferometer Space Antenna ( LISA ) with a signal-to-noise ratio of 1 .

Conclusions : Most sdB+NS binaries are located in the Galactic disk with small RV semi-amplitudes .
SdB+NS binaries with large RV semi-amplitudes are expected to be strong GWR sources , some of which could be detected by LISA in the future .