Dear Wandy, That is a very good question. Most M & A are known to fail due to lack of culture integration after the decision has been made on M & A. Often, culture issues are ignored. I am attaching two good papers that can be helpful in understanding the issues involved.

http://web.a.ebscohost.com/ehost/detail/detail?vid=4&sid=26eb2586-d8d6-42de-a73e-0451a7f64e7d%40sessionmgr4002&hid=4204&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d#db=bth&AN=7390798

http://web.a.ebscohost.com/ehost/detail/detail?vid=7&sid=26eb2586-d8d6-42de-a73e-0451a7f64e7d%40sessionmgr4002&hid=4204&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d#db=bth&AN=36272037

Thanks very much! I have just got an idea about this topic, honored to share with you and any suggestion is welcome!

I am going to make an assumption based on the marketing model, which means to take the new company culture as a new product, meanwhile take the new employees as our customers, then we can just go into a new topic: how to promote our new product in a new market with new customers.  

Be specifically. A bought B. The new integrated culture is the new product. The employees in company B before are the new customers. In order to manage the cross-culture integration, what A should do now is to introduce the new product (the new integrated culture plan) to the new customers (the employees in company B before).

I'm struggling to make the assumption more appropriate and see whether it can help to discuss this topic in a simpler way. 

Thanks for your help anyway!

Although M&A is one of the fastest ways to growth but this may not surely occur. Striking a deal will have several elements of risk in terms of cash flow, complexity of accounting rules, and "inappropriate" taxes legislations. Integration is difficult to execute unless the parties approach the matter in open mind & open heart and with "sound & reasonable" compromise. It is not a game of winners & losers among those who will "unite" and it ought not to be who becomes master & who is doomed to slavery. Justice must overcome bias & prejudice. In other words, an overall change of attitudes has to be applied to gain success for all.

M&A is age old phenomenon. It has been done in different contexts, different geographies, different industry etc. and most mergers fail, one on the main reasons being inability to integrate culturally. The merger of Daimler-Chrysler is a classic example of failure due to cultural differences. Many articles and cases have been written on this merger, especially on cultural issues between the merged companies, You can get these articles/cases on Google scholar, EBSCO, PROQUEST, EMERALD etc.

There are quite a few Ph.D thesis on this area of enquiry.

Yes, I agree with Arun. There are a number of cases of failure of M & A due to lack of cultural integration. A number of such cases can be found at Harvard Business Publishing, beside the sources he has mentioned. You may seek help of your teachers who can access these cases free as teachers. They would be of great help to you.

Yes, poor cultural integration is a common cause of failed M&As. Therefore, it is useful to study success stories. Lenovo's takoever of IBM's PC division was far from smooth, but it was ultimately successful. There are several detailed reports including a PhD study that I supervised. Here is one of the more accessible accounts:

http://www.zdnet.com/article/how-lenovo-mixed-eastern-and-western-cultures-to-take-a-chinese-firm-global/

There are a number of cases of failed mergers; however, developing and implementing a shared culture will reduce culture clashes and fuse the organizations into one entity.

As a practitioner, I had opportunity to deal with PM integration. It was challenging as well as very rewarding.

Hi! You can get some ideas from these papers:

Denison, D. R., Adkins, B., & Guidroz, A. M. (2011). Managing cultural integration in cross-border mergers and acquisitions. In Advances in global leadership. Emerald Group Publishing Limited.

Cui, M., Dong, C., Liu, Y., & Wang, S. (2016). A cultural integration path for cross-border mergers and acquisitions from the perspective of acculturation. Nankai Business Review International.

this article could be a good starting point:

Weber, Y., & Tarba, S. Y. (2012). Mergers and acquisitions process: The use of corporate culture analysis. Cross Cultural Management: An International Journal.