TY - JOUR
T1 - Newforms of half-integral weight: the minus space of Sk+1/2(Gamma(0)(8M))
T2 - the minus space of Sk+1/2(Γ0(8M))
AU - Baruch, Ehud Moshe
AU - Purkait, Soma
AU - Ehud Moshe, Baruch
N1 - Publisher Copyright:
© 2019, The Hebrew University of Jerusalem.
PY - 2019/8/1
Y1 - 2019/8/1
N2 - We compute generators and relations for a certain 2-adic Hecke algebra of level 8 associated with the double cover of SL2 and a 2-adic Hecke algebra of level 4 associated with PGL2. We show that these two Hecke algebras are isomorphic as expected from the Shimura correspondence. We use the 2-adic generators to define classical Hecke operators on the space of holomorphic modular forms of weight k + 1/2 and level 8M where M is odd and square-free. Using these operators and our previous results on half-integral weight forms of level 4M we define a subspace of the space of half-integral weight forms as a common -1 eigenspace of certain Hecke operators. Using the relations and a result of Ueda we show that this subspace, which we call the minus space, is isomorphic as a Hecke module under the Ueda correspondence to the space of new forms of weight 2k and level 4M. We observe that the forms in the minus space satisfy a Fourier coefficient condition that gives the complement of the plus space but does not define the minus space.
AB - We compute generators and relations for a certain 2-adic Hecke algebra of level 8 associated with the double cover of SL2 and a 2-adic Hecke algebra of level 4 associated with PGL2. We show that these two Hecke algebras are isomorphic as expected from the Shimura correspondence. We use the 2-adic generators to define classical Hecke operators on the space of holomorphic modular forms of weight k + 1/2 and level 8M where M is odd and square-free. Using these operators and our previous results on half-integral weight forms of level 4M we define a subspace of the space of half-integral weight forms as a common -1 eigenspace of certain Hecke operators. Using the relations and a result of Ueda we show that this subspace, which we call the minus space, is isomorphic as a Hecke module under the Ueda correspondence to the space of new forms of weight 2k and level 4M. We observe that the forms in the minus space satisfy a Fourier coefficient condition that gives the complement of the plus space but does not define the minus space.
UR - http://www.scopus.com/inward/record.url?scp=85070392769&partnerID=8YFLogxK
U2 - 10.1007/s11856-019-1873-7
DO - 10.1007/s11856-019-1873-7
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SN - 0021-2172
VL - 232
SP - 41
EP - 73
JO - Israel Journal of Mathematics
JF - Israel Journal of Mathematics
IS - 1
ER -