I would like to thank my collaborators, Prof. Emilian Dudas, Cezar Condeescu and Prof. Ioannis Florakis, for the stimulating discussions that expanded my knowledge and opened new perspectives on the topics I have been working on.A special thank is deserved to my collaborator and friend, Ivano Basile, who taught me a lot of new physics I did not know of and opened my eyes to new worlds to be explored, as well as for his kindness and availability even outside physics. His passion and enthusiasm have been stimulating and inspirational in my research activity.During these years I had the opportunity to be involved in interesting conversations, from which my work undoubtedly benefited, with many brilliant colleagues and senior scientists including Prof.

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