Improved binary black hole searches through better discrimination against noise transients

The short-duration noise transients in LIGO and Virgo detectors significantlyaffect the search sensitivity of compact binary coalescence (CBC) signals,especially in the high mass region. In the previous work by the authors\cite{Joshi_2021}, a $\chi^2$ statistic was proposed to distinguish them fromCBCs. This work is an extension where we demonstrate the improvednoise-discrimination of the optimal $\chi^2$ statistic in real LIGO data. Thetuning of the optimal $\chi^2$ includes accounting for the phase of the CBCsignal and a well informed choice of sine-Gaussian basis vectors to discern howCBC signals and some of the most worrisome noise-transients project differentlyon them~\cite{sunil_2022}. We take real blip glitches (a type of short-durationnoise disturbance) from the second observational (O2) run of LIGO-Hanford andLIGO-Livingston detectors. The binary black hole signals were simulated using\textsc{IMRPhenomPv2} waveform and injected into real LIGO data from the samerun. We show that in comparison to the traditional $\chi^2$, the optimal$\chi^2$ improves the signal detection rate by around 4\% in a lower-mass bin($m_1,m_2 \in [20,40]M_{\odot}$) and by more than 5\% in a higher-mass bin($m_1,m_2 \in [60,80]M_{\odot}$), at a false alarm probability of $10^{-3}$. Wefind that the optimal $\chi^2$ also achieves significant improvement over thesine-Gaussian $\chi^2$.