Abrupt transitions in collaborative social networks

Department of Physics, Bar Ilan University, Ramat Gan 52900, Israel CAS Key Lab of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China Beijing National Laboratory for Condensed Matter Physics & CAS Key Lab of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China Faculty of Physics and Electronics, Hubei University, Wuhan 43006, China School of Reliability and Systems Engineering, Beihang University, Beijing 100191, China Science and Technology on Reliability and Environmental Engineering Laboratory, Beijing 100191, China Department of Mathematics, Bar Ilan University, Ramat Gan 52900, Israel School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China