Liubomir Chiriac

I am an Assistant Professor at Portland State University in the Fariborz Maseeh Department of Mathematics and Statistics. Prior to PSU, I was a postdoc at UMass Amherst. I received my PhD from Caltech, under the direction of Dinakar Ramakrishnan. Before that, I was an undergraduate at Princeton University.


My research interests are in number theory, with a focus on automorphic forms and Galois representations. I am particularly interested in arithmetic and statistical properties of Fourier coefficients of modular forms. 



I am one of the organizers of Oregon Number Theory Days, a triannual number theory conference rotating between Portland State University, Oregon State University, and the University of Oregon. 


Papers

•   Summing Hecke eigenvalues over polynomials
        (joint with Liyang Yang)
        To appear in Mathematische Zeitschrift
        ( pdf )
       
•   The average number of divisors in certain arithmetic sequences
        Submitted
        ( pdf )
       
•   The trace of T₂ takes no repeated values
        (joint with Andrei Jorza)
        Indagationes Mathematicae (2022)
        ( pdf )  |  journal )


•   Newton Polygons of Hecke operators
        (joint with Andrei Jorza)
        Annales mathématiques du Québec (2021)
        ( pdf  |  journal  |  view-only )
        Data on the 2-adic valuations of the trace of T₂ is available here


•   Comparing Hecke coefficients of automorphic representations
        (joint with Andrei Jorza)
        Transactions of the American Mathematical Society (2019)
        ( pdf  |  journal )

 

•   On the equality case of the Ramanujan Conjecture for Hilbert modular forms
        International Journal of Number Theory (2019)
        ( pdf  |  journal )

 

•   On the number of dominating Fourier coefficients of two newforms
        Proceedings of the American Mathematical Society (2018)
        ( pdf  |  journal )

 



•   Comparing Hecke eigenvalues of newforms
        Archiv der Mathematik (2017)
        ( pdf  |  journal )




•   Irreducible adjoint representations in prime power dimensions, with an application
        Journal of the Ramanujan Mathematical Society (2015)
        ( pdf  |  journal )