Best way to search for human names with elasticsearch rails? - ruby-on-rails

Question

I have the following setup in my Rails 4 application via the elasticsearch-rails gem. If I search for a technical term such as "appellate" in the description field (which may be repeated more than once), I get back search results. But if I search for a name, whether first, last, or first and last, I seem to get nothing. Am I supposed to do something for string type fields? (keeping in mind that description is a text field in Rails and first and last names are string fields in Rails) Keep in mind that a first name such as "John" only appears in the first name field (last name is analogous to this), so I wonder if that is part of the issue?
class Trial < ActiveRecord::Base
include ActiveModel::Serialization
include Elasticsearch::Model
include Elasticsearch::Model::Callbacks
index_name [Rails.env, model_name.collection.gsub(/\//, '-')].join('_')
settings index: { number_of_shards: 2 } do
mappings dynamic: 'false' do
indexes :first_name, analyzer: 'english', index_options: 'offsets', copy_to: 'full_name'
indexes :last_name, analyzer: 'english', index_options: 'offsets', copy_to: 'full_name'
indexes :email, analyzer: 'english', index_options: 'offsets'
indexes :description, analyzer: 'english', index_options: 'offsets'
indexes :full_name, analyzer: 'english', index_options: 'offsets'
end
end
def self.search_trials(search_terms)
response = ClinicalTrial.search(
size: 20,
query: {
multi_match: {
"query" => search_terms,
"type" => "cross_fields",
"fields" => "_all"
}
}
)
response.records
end
end