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Research

Analytic Number Theory, Automorphic L-functions

Publications

• Manami Hosoi and Yumiko Umegaki, On the distribution of \log |L(\sigma, \chi)| and \log L(\sigma, \chi_D) in the modulus aspect, arXiv:2410.20341, to appear in Funct. Approx. Comment. Math..
• Kohji Matsumoto and Yumiko Umegaki, Asymptotic formulas for the logarithm of general L-functions at and near s=1, preprint, arXiv:2401.17610
• Philippe Lebacque, Kohji Matsumoto, Masahiro Mine and Yumiko Umegaki, On the value distribution of the logarithms of symmetric power L-functions in the level aspect, preprint, arXiv:2209.11918.
• Kohji Matsumoto and Yumiko Umegaki, On the value-distribution of symmetric power L-functions, in "Topics in Number Theory : On the Occasion of the 130th Birth Anniversary of Srinivasa Ramanujan", Ramanujan Mathematical Society Lecture Notes Series, vol. 26, Ramanujan Mathematical Society, 2020., 147--167.
• Atsuki Umegaki and Yumiko Umegaki, Quatic number fileds with large class numbers, Rocky Mountain J. Math. 50 (2020), No. 1, 267--280.
• Kohji Matsumoto and Yumiko Umegaki, On the density function for the value-distribution of automorphic L-functions, Journal of Number Theory 198 (2019) 176--199.
• Yasuko Morita, Atsuki Umegaki and Yumiko Umegaki, Bicubic number fields with large class numbers, Various Aspects of Multiple Zeta Functions (in honor of Professor Kohji Matsumoto's 60th birthday) 335-351, Adv. Stud. Pure Math. 84, Math. Soc. Japan, Tokyo, 2020.
• Kohji Matsumoto and Yumiko Umegaki, On the value-distribution of the difference between logarithms of two symmetric power L-functions, Int. J. Number Theory 14 (2018), no. 7, 2045--2081.
• Yumiko Ichihara, The first moment of L-functions of primitive forms on $\Gamma_0(p^{\alpha})$ and a basis of old forms, Journal of Number Theory vol. 131, no. 2 (2011) 343-362.
• Yumiko Ichihara, Estimates of a certain sum involving coefficients of cusp forms in weight and level aspects, Lithuanian Math. J. vol.48, no. 2 (2008) 188--202.
• Yumiko Ichihara and K. Matsumoto, On the Siegel-Tatuzawa theorem for a class of L-functions, Kyushu J. Math., vol.62 (2008), 201--215.
• Yumiko Ichihara, The evaluation of the sum over arithmetic progressions for the coefficients of the Rankin-Selberg series II, Analytic Number Theory (Beijing/Kyoto, 1999), 173--182, Dev. Math., 6, Kluwer Acad. Publ., Dordrecht,2002
• Yumiko Ichihara, The evaluation of the sum over arithmetic progressions for the coefficients of the Rankin-Selberg series, Japan. J. Math. 29 (2003), no.2, 297--314.
• Yumiko Ichihara, On Riesz mean for the coefficients of the twisted Rankin-Selberg L-functions, J. Math. Soc. Japan 55 (2003), no.1, 81--100
• Yumiko Ichihara, The Siegel-Walfisz theorem for Rankin-Selberg L-functions associated with two cusp forms, Acta Arith. 92 (2000), no. 3, 215--227.