To check for a good research gap in the field of Mergers and Acquisitions, I suggest you do the following:
1. Choose a number of peer-reviewed research papers related to your intended research, from Google Scholar, RG, SSRN or similar credible websites, not from non-credible sources.
2. Read these research papers and check for the research gaps from within such research. You may find these gaps under the subtitle: Future Research or similar subtitles.
3. Ensure that such gaps are not already covered by recent research. That is, for the gap that you want to cover, read to the last current research in this regard to make sure that no other author(s) already conducted such research.
4. Then, go ahead and start preparing for your research, preferably using the Literature Review Matrix where you put a table showing authors, title, objectives, research question(s), problem statement, variables, methodologies used, findings, etc. for each research paper selected. By the way, you may want to keep such relevant research papers to use them as references in your research.
To identify a research gap in M&A, it's best to first narrow down your focus—e.g., cross-border deals, post-merger integration, or digital M&A. Gaps vary by subfield and context. I suggest reviewing recent literature in top journals (e.g., Strategic Management Journal, Journal of Corporate Finance), then refining your scope. Once you’ve shortlisted a few themes, others can better help with targeted insights and citations.