{"id":{"repo_id":"queens","oai_identifier":"oai:queensu.scholaris.ca:1974/30300"},"canonical_url":"https://search.dev.ndltd.org/etd/queens/oai:queensu.scholaris.ca:1974/30300","repository":{"repo_id":"queens","name":"Queens University","base_url":"https://qspace.library.queensu.ca/server/oai/request"},"display":{"title":"Tail Asymptotics for the Limiting Distribution of Theta Sums","abstract":"We define theta sums to be exponential sums of the form S_{N}(x; \\alpha, \\beta) := \\sum_{n =1}^{N} e((\\tfrac{1}{2} n^2 + \\beta n)x + \\alpha n), where e(z) = e^{2 \\pi i z}. If \\alpha and \\beta are fixed rational numbers, and x is chosen randomly from the unit interval, we use homogeneous dynamics to show that \\tfrac{1}{N}S_{\\lfloor sN\\rfloor}S_{\\lfloor tN\\rfloor}, possesses a limiting distribution as N goes to infinity, for any s,t \\in \\mathbb{R}, and that this limiting distribution depends on the initial choice of \\alpha and \\beta. We then prove optimal tail asymptotics for the limiting distribution. More specifically, we prove that, according to the limiting distribution, the probability of landing outside a ball of sufficiently large radius $R$ for an explicit set of rational pairs (\\alpha, \\beta) is 0. For all other rational pairs (\\alpha,\\beta) we show that this probability is asymptotic to \\tfrac{C_{\\alpha,\\beta}D_{s,t}}{\\pi^2 R^4}(1 + O_{\\varepsilon}(R^{-2 + \\varepsilon})) for any \\varepsilon > 0, where C_{\\alpha,\\beta} and D_{s,t} are explicit, positive constants. These results, in particular, imply that the limiting distribution of \\tfrac{1}{N}S_{\\lfloor sN\\rfloor}S_{\\lfloor tN\\rfloor} when (\\alpha,\\beta) are rational, cannot be a Gaussian. This complements existing work of F. Cellarosi and J. Marklof when (\\alpha,\\beta) \\in \\mathbb{R}^2\\setminus \\mathbb{Q}^2, and completes the classification of the limiting tail behaviour of theta sums. For the rational parameters that lead to compact support, we are able to prove a uniform bound for generalised theta sums S^f_N (x; \\alpha,\\beta) := \\sum_{n\\in \\Z} f(\\tfrac{n}{N}) e((\\tfrac{1}{2} n^2 + \\beta n)x + \\alpha n), provided the weight function f is sufficiently regular.","abstract_html":"We define theta sums to be exponential sums of the form S_{N}(x; \\alpha, \\beta) := \\sum_{n =1}^{N} e((\\tfrac{1}{2} n^2 + \\beta n)x + \\alpha n), where e(z) = e^{2 \\pi i z}. If \\alpha and \\beta are fixed rational numbers, and x is chosen randomly from the unit interval, we use homogeneous dynamics to show that \\tfrac{1}{N}S_{\\lfloor sN\\rfloor}S_{\\lfloor tN\\rfloor}, possesses a limiting distribution as N goes to infinity, for any s,t \\in \\mathbb{R}, and that this limiting distribution depends on the initial choice of \\alpha and \\beta. We then prove optimal tail asymptotics for the limiting distribution. More specifically, we prove that, according to the limiting distribution, the probability of landing outside a ball of sufficiently large radius $R$ for an explicit set of rational pairs (\\alpha, \\beta) is 0. For all other rational pairs (\\alpha,\\beta) we show that this probability is asymptotic to \\tfrac{C_{\\alpha,\\beta}D_{s,t}}{\\pi^2 R^4}(1 + O_{\\varepsilon}(R^{-2 + \\varepsilon})) for any \\varepsilon > 0, where C_{\\alpha,\\beta} and D_{s,t} are explicit, positive constants. These results, in particular, imply that the limiting distribution of \\tfrac{1}{N}S_{\\lfloor sN\\rfloor}S_{\\lfloor tN\\rfloor} when (\\alpha,\\beta) are rational, cannot be a Gaussian. This complements existing work of F. Cellarosi and J. Marklof when (\\alpha,\\beta) \\in \\mathbb{R}^2\\setminus \\mathbb{Q}^2, and completes the classification of the limiting tail behaviour of theta sums. For the rational parameters that lead to compact support, we are able to prove a uniform bound for generalised theta sums S^f_N (x; \\alpha,\\beta) := \\sum_{n\\in \\Z} f(\\tfrac{n}{N}) e((\\tfrac{1}{2} n^2 + \\beta n)x + \\alpha n), provided the weight function f is sufficiently regular.","abstract_has_math":true,"creators":["Osman, Tariq"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":"Mathematics and Statistics","school":null,"contributors":[],"advisors":["Cellarosi, Francesco"],"committee_chairs":[],"committee_members":[],"year":null,"date_issued":"","date_published":null,"updated_at":"2026-07-27T20:35:35Z","subjects":["Probability Theory","Number Theory","Dynamical Systems"],"languages":["eng"],"rights":["Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada","ProQuest PhD and Master's Theses International Dissemination Agreement","Intellectual Property Guidelines at Queen's University","Copying and Preserving Your Thesis","This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.","Attribution 3.0 United States"],"rights_urls":["http://creativecommons.org/licenses/by/3.0/us/"],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/1974/30300","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.department","label":"Department","values":["Mathematics and Statistics"]},{"key":"dc:contributor.supervisor","label":"Supervisor","values":["Cellarosi, Francesco"]},{"key":"dc:creator","label":"Author","values":["Osman, Tariq"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2022-08-12T14:38:05Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2022-08-12T14:38:05Z"]},{"key":"dc:type","label":"Dc Type","values":["thesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Probability Theory","Number Theory","Dynamical Systems"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada","ProQuest PhD and Master's Theses International Dissemination Agreement","Intellectual Property Guidelines at Queen's University","Copying and Preserving Your Thesis","This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.","Attribution 3.0 United States"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://creativecommons.org/licenses/by/3.0/us/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/1974/30300"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["We define theta sums to be exponential sums of the form S_{N}(x; \\alpha, \\beta) := \\sum_{n =1}^{N} e((\\tfrac{1}{2} n^2 + \\beta n)x + \\alpha n), where e(z) = e^{2 \\pi i z}. If \\alpha and \\beta are fixed rational numbers, and x is chosen randomly from the unit interval, we use homogeneous dynamics to show that \\tfrac{1}{N}S_{\\lfloor sN\\rfloor}S_{\\lfloor tN\\rfloor}, possesses a limiting distribution as N goes to infinity, for any s,t \\in \\mathbb{R}, and that this limiting distribution depends on the initial choice of \\alpha and \\beta. We then prove optimal tail asymptotics for the limiting distribution. More specifically, we prove that, according to the limiting distribution, the probability of landing outside a ball of sufficiently large radius $R$ for an explicit set of rational pairs (\\alpha, \\beta) is 0. For all other rational pairs (\\alpha,\\beta) we show that this probability is asymptotic to \\tfrac{C_{\\alpha,\\beta}D_{s,t}}{\\pi^2 R^4}(1 + O_{\\varepsilon}(R^{-2 + \\varepsilon})) for any \\varepsilon > 0, where C_{\\alpha,\\beta} and D_{s,t} are explicit, positive constants. These results, in particular, imply that the limiting distribution of \\tfrac{1}{N}S_{\\lfloor sN\\rfloor}S_{\\lfloor tN\\rfloor} when (\\alpha,\\beta) are rational, cannot be a Gaussian. This complements existing work of F. Cellarosi and J. Marklof when (\\alpha,\\beta) \\in \\mathbb{R}^2\\setminus \\mathbb{Q}^2, and completes the classification of the limiting tail behaviour of theta sums. For the rational parameters that lead to compact support, we are able to prove a uniform bound for generalised theta sums S^f_N (x; \\alpha,\\beta) := \\sum_{n\\in \\Z} f(\\tfrac{n}{N}) e((\\tfrac{1}{2} n^2 + \\beta n)x + \\alpha n), provided the weight function f is sufficiently regular."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["PhD"]},{"key":"dc:title","label":"Title","values":["Tail Asymptotics for the Limiting Distribution of Theta Sums"]}]}],"canonical_facts":{"dc:contributor.department":["Mathematics and Statistics"],"dc:contributor.supervisor":["Cellarosi, Francesco"],"dc:creator":["Osman, Tariq"],"dc:date.accessioned":["2022-08-12T14:38:05Z"],"dc:date.available":["2022-08-12T14:38:05Z"],"dc:description.abstract":["We define theta sums to be exponential sums of the form S_{N}(x; \\alpha, \\beta) := \\sum_{n =1}^{N} e((\\tfrac{1}{2} n^2 + \\beta n)x + \\alpha n), where e(z) = e^{2 \\pi i z}. If \\alpha and \\beta are fixed rational numbers, and x is chosen randomly from the unit interval, we use homogeneous dynamics to show that \\tfrac{1}{N}S_{\\lfloor sN\\rfloor}S_{\\lfloor tN\\rfloor}, possesses a limiting distribution as N goes to infinity, for any s,t \\in \\mathbb{R}, and that this limiting distribution depends on the initial choice of \\alpha and \\beta. We then prove optimal tail asymptotics for the limiting distribution. More specifically, we prove that, according to the limiting distribution, the probability of landing outside a ball of sufficiently large radius $R$ for an explicit set of rational pairs (\\alpha, \\beta) is 0. For all other rational pairs (\\alpha,\\beta) we show that this probability is asymptotic to \\tfrac{C_{\\alpha,\\beta}D_{s,t}}{\\pi^2 R^4}(1 + O_{\\varepsilon}(R^{-2 + \\varepsilon})) for any \\varepsilon > 0, where C_{\\alpha,\\beta} and D_{s,t} are explicit, positive constants. These results, in particular, imply that the limiting distribution of \\tfrac{1}{N}S_{\\lfloor sN\\rfloor}S_{\\lfloor tN\\rfloor} when (\\alpha,\\beta) are rational, cannot be a Gaussian. This complements existing work of F. Cellarosi and J. Marklof when (\\alpha,\\beta) \\in \\mathbb{R}^2\\setminus \\mathbb{Q}^2, and completes the classification of the limiting tail behaviour of theta sums. For the rational parameters that lead to compact support, we are able to prove a uniform bound for generalised theta sums S^f_N (x; \\alpha,\\beta) := \\sum_{n\\in \\Z} f(\\tfrac{n}{N}) e((\\tfrac{1}{2} n^2 + \\beta n)x + \\alpha n), provided the weight function f is sufficiently regular."],"dc:description.degree":["PhD"],"dc:identifier.uri":["http://hdl.handle.net/1974/30300"],"dc:language.iso":["eng"],"dc:rights":["Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada","ProQuest PhD and Master's Theses International Dissemination Agreement","Intellectual Property Guidelines at Queen's University","Copying and Preserving Your Thesis","This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.","Attribution 3.0 United States"],"dc:rights.uri":["http://creativecommons.org/licenses/by/3.0/us/"],"dc:subject":["Probability Theory","Number Theory","Dynamical Systems"],"dc:title":["Tail Asymptotics for the Limiting Distribution of Theta Sums"],"dc:type":["thesis"]},"updated_at":"2026-07-27T20:35:35Z"}