SubmissionNumber#=%=#261 FinalPaperTitle#=%=#Team MGTD4ADL at SemEval-2024 Task 8: Leveraging (Sentence) Transformer Models with Contrastive Learning for Identifying Machine-Generated Text ShortPaperTitle#=%=# NumberOfPages#=%=#8 CopyrightSigned#=%=#Ercong Nie JobTitle#==# Organization#==#Center for Information and Language Processing, Ludwig Maximilians University of Munich Oettingenstraße 67, 80538 Munich, Germany Abstract#==#This paper outlines our approach to SemEval-2024 Task 8 (Subtask B), which focuses on discerning machine-generated text from human-written content, while also identifying the text sources, i.e., from which Large Language Model (LLM) the target text is generated. Our detection system is built upon Transformer-based techniques, leveraging various pre-trained language models (PLMs), including sentence transformer models. Additionally, we incorporate Contrastive Learning (CL) into the classifier to improve the detecting capabilities and employ Data Augmentation methods. Ultimately, our system achieves a peak accuracy of 76.96% on the test set of the competition, configured using a sentence transformer model integrated with CL methodology. Author{1}{Firstname}#=%=#Huixin Author{1}{Lastname}#=%=#Chen Author{1}{Username}#=%=#chenhuixin Author{1}{Email}#=%=#huixin333666@gmail.com Author{1}{Affiliation}#=%=#Ludwig Maximilian University of Munich Author{2}{Firstname}#=%=#Jan Author{2}{Lastname}#=%=#Büssing Author{2}{Email}#=%=#jan.buessing@campus.lmu.de Author{2}{Affiliation}#=%=#Institute for Statistics, LMU Munich Author{3}{Firstname}#=%=#David Author{3}{Lastname}#=%=#Rügamer Author{3}{Email}#=%=#david.ruegamer@stat.uni-muenchen.de Author{3}{Affiliation}#=%=#Institute for Statistics, LMU Munich Author{4}{Firstname}#=%=#Ercong Author{4}{Lastname}#=%=#Nie Author{4}{Username}#=%=#ercong Author{4}{Email}#=%=#nie@cis.lmu.de Author{4}{Affiliation}#=%=#Centre for Information and Language Processing, LMU Munich ========== èéáğö