Geometrical compression: a new method to enhance the BOSS galaxy
  bispectrum monopole constraints
  We present a novel method to compress galaxy clustering three-point
statistics and apply it to redshift space galaxy bispectrum monopole
measurements from BOSS DR12 CMASS data considering a $k$-space range of
$0.03-0.12\,h/\mathrm{Mpc}$. The method consists in binning together bispectra
evaluated at sets of wave-numbers forming closed triangles with similar
geometrical properties: the area, the cosine of the largest angle and the ratio
between the cosines of the remaining two angles. This enables us to increase
the number of bispectrum measurements for example by a factor of $23$ over the
standard binning (from 116 to 2734 triangles used), which is otherwise limited
by the number of mock catalogues available to estimate the covariance matrix
needed to derive parameter constraints. The $68\%$ credible intervals for the
inferred parameters $\left(b_1,b_2,f,\sigma_8\right)$ are thus reduced by
$\left(-39\%,-49\%,-29\%,-22\%\right)$, respectively. We find very good
agreement with the posteriors recently obtained by alternative maximal
compression methods. This new method does not require the a-priori computation
of the data-vector covariance matrix and has the potential to be directly
applicable to other three-point statistics (e.g. glaxy clustering, weak
gravitational lensing, 21 cm emission line) measured from future surveys such
as DESI, Euclid, PFS and SKA.
