I have gone through the default scoring function that elasticsearch uses.
score(q,d) = queryNorm(q) * coord(q,d) * SUM ( tf(t in d), idf(t)², t.getBoost(), norm(t,d) ) (t in q)
score(q,d) is the relevance score of document d for query q.
queryNorm(q) is the query normalization factor.
coord(q,d) is the coordination factor.
The sum of the weights for each term t in the query q for document d.
tf(t in d) is the term frequency for term t in document d.
idf(t) is the inverse document frequency for term t.
t.getBoost() is the boost that has been applied to the query.
norm(t,d) is the field-length norm, combined with the index-time field-level boost, if any.
I want to use Coordination factor alone as my score.
Any help here is highly appreciated.