Given your schema the stemmer seems a very likely responsible.
You need to disable it and re-index.
Just commenting it is not going to work if you don't re-index.

Cheers

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Alessandro Benedetti
Search Consultant, R&D Software Engineer, Director
Sease Ltd. - www.sease.io
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Sent from: http://lucene.472066.n3.nabble.com/Solr-User-f472068.html
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