jpa many to many child list not persisted - jpa

Question

I have a senario where there is an entity Article, an entity Author and a join table Article_Author. Article and Author have a many to many relationship ( on article can have many authors and an author can have many articles).
here are my entities classes :
Author class:
#Entity
#Table(name="AUTHOR")
#NamedQuery(name="Author.findAll", query="SELECT a FROM Author a")
public class Author implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#Column(name="AUTHOR_CODE")
private String authorCode;
private String nom;
//bi-directional many-to-many association to Article
#ManyToMany(fetch=FetchType.EAGER)
#JoinTable(
name="ARTICLE_AUTHOR"
, joinColumns={
#JoinColumn(name="AUTHOR")
}
, inverseJoinColumns={
#JoinColumn(name="ART_REF")
}
)
private List<Article> article;
}
//getters and setters + hashcode and equals methods
Article class :
#Entity
#Table(name="ARTICLE_TEST")
#NamedQuery(name="ArticleTest.findAll", query="SELECT a FROM ArticleTest a")
public class ArticleTest implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#Column(name="ART_REF")
private String artRef;
#Column(name="ART_TITRE")
private String artTitre;
//bi-directional many-to-many association to AutheurTest
#ManyToMany(mappedBy="articleTests", fetch=FetchType.EAGER)
private List<AutheurTest> autheurTests;
//getters and setters + hashcode and equals methods
}
and here is the code where I create an article and attach one author (for testing) :
//.....
AutheurTest aut1 = new AutheurTest();
AutheurTest aut2 = new AutheurTest();
aut1.setAutheurCode("1");
aut1.setNom("AUT1");
articlemodelBean.createautheurtest(aut1);
ArticleTest art1 = new ArticleTest();
art1.setArtRef("A");
art1.setArtTitre("ART1");
articlemodelBean.dmlArticle_test(art1,"insert"); //persist art1
AutheurTest newaut = articlemodelBean.getAuteurActive_test(aut1.getAutheurCode());
ArticleTest foundedart = articlemodelBean.findArticle_test(art1.getArtRef()); //getting the article
foundedart.getAutheurTests().add(newaut);
articlemodelBean.artaut(foundedart); //merge foudedart
//.....
So I'm not getting any error, both the article and author are added to database! but the foreign keys are not inserted into the join table. so basically the author is not attached to the article.