{"title":"Transcendental Brauer-Manin obstructions on singular K3 surfaces.","authors":"Mohamed Alaa Tawfik, Rachel Newton","doi":"10.1007/s40993-024-00580-z","DOIUrl":"10.1007/s40993-024-00580-z","url":null,"abstract":"<p><p>Let <i>E</i> and <math><msup><mi>E</mi> <mo>'</mo></msup> </math> be elliptic curves over <math><mi>Q</mi></math> with complex multiplication by the ring of integers of an imaginary quadratic field <i>K</i> and let <math><mrow><mi>Y</mi> <mo>=</mo> <mrow><mspace></mspace> <mtext>Kum</mtext> <mspace></mspace></mrow> <mo>(</mo> <mi>E</mi> <mo>×</mo> <msup><mi>E</mi> <mo>'</mo></msup> <mo>)</mo></mrow> </math> be the minimal desingularisation of the quotient of <math><mrow><mi>E</mi> <mo>×</mo> <msup><mi>E</mi> <mo>'</mo></msup> </mrow> </math> by the action of <math><mrow><mo>-</mo> <mn>1</mn></mrow> </math> . We study the Brauer groups of such surfaces <i>Y</i> and use them to furnish new examples of transcendental Brauer-Manin obstructions to weak approximation.</p>","PeriodicalId":43826,"journal":{"name":"Research in Number Theory","volume":"11 1","pages":"16"},"PeriodicalIF":0.6,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11655618/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142878096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Fourier-Jacobi Dirichlet series for cusp forms on orthogonal groups.","authors":"Rafail Psyroukis","doi":"10.1007/s40993-025-00668-0","DOIUrl":"https://doi.org/10.1007/s40993-025-00668-0","url":null,"abstract":"<p><p>We investigate a Dirichlet series involving the Fourier-Jacobi coefficients of two cusp forms <i>F</i>, <i>G</i> for orthogonal groups of signature <math><mrow><mo>(</mo> <mn>2</mn> <mo>,</mo> <mi>n</mi> <mo>+</mo> <mn>2</mn> <mo>)</mo></mrow> </math> . In the case when <i>F</i> is a Hecke eigenform and <i>G</i> is a Maass lift of a Poincaré series, we establish a connection with the standard <i>L</i>-function attached to <i>F</i>. What is more, we find explicit choices of orthogonal groups, for which we obtain a clear-cut Euler product expression for this Dirichlet series. Through our considerations, we recover a classical result for Siegel modular forms, first introduced by Kohnen and Skoruppa, but also provide a range of new examples, which can be related to other kinds of modular forms, such as paramodular, Hermitian, and quaternionic.</p>","PeriodicalId":43826,"journal":{"name":"Research in Number Theory","volume":"11 4","pages":"90"},"PeriodicalIF":0.8,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12449435/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145114578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Traces of partition Eisenstein series and almost holomorphic modular forms.","authors":"Kathrin Bringmann, Badri Vishal Pandey","doi":"10.1007/s40993-025-00615-z","DOIUrl":"10.1007/s40993-025-00615-z","url":null,"abstract":"<p><p>Recently, Amdeberhan, Griffin, Ono, and Singh started the study of \"traces of partition Eisenstein series\" and used it to give explicit formulas for many interesting functions. In this note we determine the precise spaces in which they lie, find modular completions, and show how they are related via operators.</p>","PeriodicalId":43826,"journal":{"name":"Research in Number Theory","volume":"11 2","pages":"49"},"PeriodicalIF":0.6,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12018508/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143989987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Constructing families of 3-Selmer companions.","authors":"Harry Spencer","doi":"10.1007/s40993-025-00647-5","DOIUrl":"https://doi.org/10.1007/s40993-025-00647-5","url":null,"abstract":"<p><p>Mazur and Rubin introduced the notion of <i>n</i>-Selmer companion elliptic curves and gave several examples of pairs of non-isogenous Selmer companions. We construct several pairs of families of elliptic curves, each parameterised by <math><mrow><mi>t</mi> <mo>∈</mo> <mi>Z</mi></mrow> </math> , such that the two curves in a pair corresponding to a given <i>t</i> are non-isogenous 3-Selmer companions, possibly provided that <i>t</i> satisfies a simple congruence condition.</p>","PeriodicalId":43826,"journal":{"name":"Research in Number Theory","volume":"11 3","pages":"67"},"PeriodicalIF":0.6,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12227473/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144576602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Daniel Barrera Salazar, Andrew Graham, Chris Williams
{"title":"<ArticleTitle xmlns:ns0=\"http://www.w3.org/1998/Math/MathML\">On <i>p</i>-refined Friedberg-Jacquet integrals and the classical symplectic locus in the <ns0:math> <ns0:msub><ns0:mrow><ns0:mspace /> <ns0:mtext>GL</ns0:mtext> <ns0:mspace /></ns0:mrow> <ns0:mrow><ns0:mn>2</ns0:mn> <ns0:mi>n</ns0:mi></ns0:mrow> </ns0:msub> </ns0:math> eigenvariety.","authors":"Daniel Barrera Salazar, Andrew Graham, Chris Williams","doi":"10.1007/s40993-025-00631-z","DOIUrl":"https://doi.org/10.1007/s40993-025-00631-z","url":null,"abstract":"<p><p>Friedberg-Jacquet proved that if <math><mi>π</mi></math> is a cuspidal automorphic representation of <math> <mrow><msub><mtext>GL</mtext> <mrow><mn>2</mn> <mi>n</mi></mrow> </msub> <mrow><mo>(</mo> <mi>A</mi> <mo>)</mo></mrow> </mrow> </math> , then <math><mi>π</mi></math> is a functorial transfer from <math><msub><mtext>GSpin</mtext> <mrow><mn>2</mn> <mi>n</mi> <mo>+</mo> <mn>1</mn></mrow> </msub> </math> if and only if a global zeta integral <math><msub><mi>Z</mi> <mi>H</mi></msub> </math> over <math><mrow><mi>H</mi> <mo>=</mo> <msub><mtext>GL</mtext> <mi>n</mi></msub> <mo>×</mo> <msub><mtext>GL</mtext> <mi>n</mi></msub> </mrow> </math> is non-vanishing on <math><mi>π</mi></math> . We conjecture a <i>p</i>-refined analogue: that any <i>P</i>-parahoric <i>p</i>-refinement <math> <msup><mover><mi>π</mi> <mo>~</mo></mover> <mi>P</mi></msup> </math> is a functorial transfer from <math><msub><mtext>GSpin</mtext> <mrow><mn>2</mn> <mi>n</mi> <mo>+</mo> <mn>1</mn></mrow> </msub> </math> if and only if a <i>P</i>-twisted version of <math><msub><mi>Z</mi> <mi>H</mi></msub> </math> is non-vanishing on the <math> <msup><mover><mi>π</mi> <mo>~</mo></mover> <mi>P</mi></msup> </math> -eigenspace in <math><mi>π</mi></math> . This twisted <math><msub><mi>Z</mi> <mi>H</mi></msub> </math> appears in all constructions of <i>p</i>-adic <i>L</i>-functions via Shalika models. We connect our conjecture to the study of classical symplectic families in the <math><msub><mtext>GL</mtext> <mrow><mn>2</mn> <mi>n</mi></mrow> </msub> </math> eigenvariety, and-by proving upper bounds on the dimensions of such families-obtain various results towards the conjecture.</p>","PeriodicalId":43826,"journal":{"name":"Research in Number Theory","volume":"11 2","pages":"51"},"PeriodicalIF":0.6,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12031854/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144028936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Three-torsion subgroups and wild conductor exponents of plane quartics.","authors":"Elvira Lupoian, James Rawson","doi":"10.1007/s40993-025-00672-4","DOIUrl":"https://doi.org/10.1007/s40993-025-00672-4","url":null,"abstract":"<p><p>In this paper we give an algorithm to find the 3-torsion subgroup of the Jacobian of a smooth plane quartic curve with a marked rational point. We describe <math><mrow><mn>3</mn> <mo>-</mo></mrow> </math> torsion points in terms of cubics which triply intersect the curve, and use this to define a system of equations whose solution set corresponds to the coefficients of these cubics. We compute the points of this zero-dimensional, degree 728 scheme first by approximation, using homotopy continuation and Newton-Raphson, and then using continued fractions to obtain accurate expressions for these points. We describe how the Galois structure of the field of definition of the 3-torsion subgroup can be used to compute local wild conductor exponents, including at <math><mrow><mi>p</mi> <mo>=</mo> <mn>2</mn></mrow> </math> .</p>","PeriodicalId":43826,"journal":{"name":"Research in Number Theory","volume":"11 4","pages":"92"},"PeriodicalIF":0.8,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12496290/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145240026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}