"the connection between" is an acceptable and usable phrase in written English. It is generally used when describing a link or relationship between two or more things. For example, "The connection between the rise in prices and the increase in inflation was evident.".
The connection between memory and fear.
What is the connection between the two?
The connection between Labour and L.S.E.
The connection between lender and borrower vanished.
The connection between plants and alcoholic spirits.
The connection between us is really special.
What's the connection between Beuys and water?
Since I tried Ludwig back in 2017, I have been constantly using it in both editing and translation. Ever since, I suggest it to my translators at ProSciEditing.
Justyna Jupowicz-Kozak
CEO of Professional Science Editing for Scientists @ prosciediting.com