  Polar codes have attracted the attention of numerous researchers in the past
decade due to their excellent performance. However, their performance at short
block lengths under standard successive cancellation decoding is far from
desirable. An effective method to improve the performance at short lengths is
CRC precoding followed by successive-cancellation list decoding. Later, Arikan
presented polarization-adjusted convolutional (PAC) codes, which further
improve the performance of polar codes. In fact, bit-flipping is another
post-processing method that can improve decoding performance. In this paper, we
propose a novel SCL Bit-Flipping of PAC Codes. We show that better performance
can be achieved using list decoding when the list size is the same for PAC
codes (N=128, K=64). The decoding performance of our newly proposed PAC-SCLF
with a list size of 32 is 0.3 dB better than that of the traditional PAC-SCL
with a list size of 32. We set the maximum number of bit flips to 5. The
performance of the list size (L=32) for PAC-SCLF is almost the same as the
performance of the list size (L=128) for PAC-SCL.
