{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/30685"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/30685","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Quantum field theories on the light front","abstract":"Several popular field theories are quantized on light fronts, that is O 3 surfaces defined by x + = x0 + x3 = constant. Schwinger's quantum ac tion principle is employed to deduce the correct canonical equal-x+(anti-) commutation relations. The formulations developed for free fields of spin-o,-t,-l, and -2 are equivalent to the equal-time formulations. However, in the new formulations it is easy to take the limit of vanishing mass in the massive spin-2 theory. Consistent formulations are found for self-interacting scalar fields and for scalar and Dirac fields interacting through simple couplings. The S-matrix elements are given by a x+-ordered product rather than the usual time-ordered product. The Feynman rules for these S-matrix elements are identical to the old rules in the case of the self-interacting scalar theory, but they differ by noncovariant terms for the interacting Dirac theory. A formal proof of the equivalence of the S-m3trix in the new formulation and the usual time-ordered expansion is given for renormalized interacting Dirac fields. A set of generalized Schwinger conditions for a quantum theory to be Lorentz invariant are verified in scalar and Dirac field theories; then the presence of c-number Schwinger terms in the equal-x+ stress tensor commutators is demonstrated. This new formulation is used to find spectral sum rules and leading singularities of both the Green's function and the product of field operators near the light front. The implications for current algebra sum rules are mentioned. Reduction formulas for scalar and Dirac particles are derived.","abstract_html":"Several popular field theories are quantized on light fronts, that is O 3 surfaces defined by x + = x0 + x3 = constant. Schwinger's quantum ac tion principle is employed to deduce the correct canonical equal-x+(anti-) commutation relations. The formulations developed for free fields of spin-o,-t,-l, and -2 are equivalent to the equal-time formulations. However, in the new formulations it is easy to take the limit of vanishing mass in the massive spin-2 theory. Consistent formulations are found for self-interacting scalar fields and for scalar and Dirac fields interacting through simple couplings. The S-matrix elements are given by a x+-ordered product rather than the usual time-ordered product. The Feynman rules for these S-matrix elements are identical to the old rules in the case of the self-interacting scalar theory, but they differ by noncovariant terms for the interacting Dirac theory. A formal proof of the equivalence of the S-m3trix in the new formulation and the usual time-ordered expansion is given for renormalized interacting Dirac fields. A set of generalized Schwinger conditions for a quantum theory to be Lorentz invariant are verified in scalar and Dirac field theories; then the presence of c-number Schwinger terms in the equal-x+ stress tensor commutators is demonstrated. This new formulation is used to find spectral sum rules and leading singularities of both the Green's function and the product of field operators near the light front. The implications for current algebra sum rules are mentioned. Reduction formulas for scalar and Dirac particles are derived.","abstract_has_math":false,"creators":["Root, Robert Gerald"],"institution":null,"degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":["Chang, Shau-Jin"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2012,"date_issued":"2012-04-19T20:44:46Z","date_published":"2012-04-19T20:44:46Z","updated_at":"2026-07-22T22:25:29Z","subjects":["light fronts","quantum mechanics","quantum field theories"],"languages":["en"],"rights":["© 1973 Robert Gerald Root"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["2367971"],"render_values":[{"text":"2367971","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/30685","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Chang, Shau-Jin"]},{"key":"dc:creator","label":"Author","values":["Root, Robert Gerald"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2012-04-19T20:44:46Z","10000-01-01","1973"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation / Thesis","text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Physics"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["light fronts","quantum mechanics","quantum field theories"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["© 1973 Robert Gerald Root"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["2367971","http://hdl.handle.net/2142/30685"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Several popular field theories are quantized on light fronts, that is O 3 surfaces defined by x + = x0 + x3 = constant. Schwinger's quantum ac tion principle is employed to deduce the correct canonical equal-x+(anti-) commutation relations. The formulations developed for free fields of spin-o,-t,-l, and -2 are equivalent to the equal-time formulations. However, in the new formulations it is easy to take the limit of vanishing mass in the massive spin-2 theory. Consistent formulations are found for self-interacting scalar fields and for scalar and Dirac fields interacting through simple couplings. The S-matrix elements are given by a x+-ordered product rather than the usual time-ordered product. The Feynman rules for these S-matrix elements are identical to the old rules in the case of the self-interacting scalar theory, but they differ by noncovariant terms for the interacting Dirac theory. A formal proof of the equivalence of the S-m3trix in the new formulation and the usual time-ordered expansion is given for renormalized interacting Dirac fields. A set of generalized Schwinger conditions for a quantum theory to be Lorentz invariant are verified in scalar and Dirac field theories; then the presence of c-number Schwinger terms in the equal-x+ stress tensor commutators is demonstrated. This new formulation is used to find spectral sum rules and leading singularities of both the Green's function and the product of field operators near the light front. The implications for current algebra sum rules are mentioned. Reduction formulas for scalar and Dirac particles are derived.","Submitted by Megan O'Donnell (mnodonn2@illinois.edu) on 2012-04-19T20:44:46Z No. of bitstreams: 1 1973_root.pdf: 4947960 bytes, checksum: cd8bd8031ddc28830d6b13049e8221f8 (MD5)","Made available in DSpace on 2012-04-19T20:44:46Z (GMT). No. of bitstreams: 1 1973_root.pdf: 4947960 bytes, checksum: cd8bd8031ddc28830d6b13049e8221f8 (MD5) Previous issue date: 1973","Restriction data tranferred 2014-07-01T11:34:50-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: dissertation/thesis","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Megan O'Donnell (mnodonn2@illinois.edu) on 2012-04-19T20:44:46Z Item is restricted indefinitely.","dissertation/thesis","U of I Only"]},{"key":"dc:title","label":"Title","values":["Quantum field theories on the light front"]}]}],"canonical_facts":{"dc:contributor":["Chang, Shau-Jin"],"dc:creator":["Root, Robert Gerald"],"dc:date":["2012-04-19T20:44:46Z","10000-01-01","1973"],"dc:description":["Several popular field theories are quantized on light fronts, that is O 3 surfaces defined by x + = x0 + x3 = constant. Schwinger's quantum ac tion principle is employed to deduce the correct canonical equal-x+(anti-) commutation relations. The formulations developed for free fields of spin-o,-t,-l, and -2 are equivalent to the equal-time formulations. However, in the new formulations it is easy to take the limit of vanishing mass in the massive spin-2 theory. Consistent formulations are found for self-interacting scalar fields and for scalar and Dirac fields interacting through simple couplings. The S-matrix elements are given by a x+-ordered product rather than the usual time-ordered product. The Feynman rules for these S-matrix elements are identical to the old rules in the case of the self-interacting scalar theory, but they differ by noncovariant terms for the interacting Dirac theory. A formal proof of the equivalence of the S-m3trix in the new formulation and the usual time-ordered expansion is given for renormalized interacting Dirac fields. A set of generalized Schwinger conditions for a quantum theory to be Lorentz invariant are verified in scalar and Dirac field theories; then the presence of c-number Schwinger terms in the equal-x+ stress tensor commutators is demonstrated. This new formulation is used to find spectral sum rules and leading singularities of both the Green's function and the product of field operators near the light front. The implications for current algebra sum rules are mentioned. Reduction formulas for scalar and Dirac particles are derived.","Submitted by Megan O'Donnell (mnodonn2@illinois.edu) on 2012-04-19T20:44:46Z No. of bitstreams: 1 1973_root.pdf: 4947960 bytes, checksum: cd8bd8031ddc28830d6b13049e8221f8 (MD5)","Made available in DSpace on 2012-04-19T20:44:46Z (GMT). No. of bitstreams: 1 1973_root.pdf: 4947960 bytes, checksum: cd8bd8031ddc28830d6b13049e8221f8 (MD5) Previous issue date: 1973","Restriction data tranferred 2014-07-01T11:34:50-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: dissertation/thesis","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Megan O'Donnell (mnodonn2@illinois.edu) on 2012-04-19T20:44:46Z Item is restricted indefinitely.","dissertation/thesis","U of I Only"],"dc:identifier":["2367971","http://hdl.handle.net/2142/30685"],"dc:language":["en"],"dc:rights":["© 1973 Robert Gerald Root"],"dc:subject":["light fronts","quantum mechanics","quantum field theories"],"dc:title":["Quantum field theories on the light front"],"dc:type":["Dissertation / Thesis","text"],"thesis:degree_discipline":["Physics"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."]},"updated_at":"2026-07-22T22:25:29Z"}