Watson Discovery Service Keyword search combined query

How to perform a keyword search using watson discovery service? For example .

following query can be used to find articles in News dataset with keyword “IBM Watson”

keywords:(text:IBM Watson)

But how to fetch articles in News dataset with keyword “IBM Watson” where relevance is greater than 0.9.?The following query doesn’t work:

keyword:(text:IBM Watson, relevance>0.9)

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