In this thesis we study radiative decays of the exotic meson X(3872) into $J/ \\psi \\gamma$ and $\\psi(2S) \\gamma$ using an effective field theory framework. Assuming the exotic meson to be primarily a molecular state of the mesons $D$ and $ \\bar{D}^{*}$, we perform a renormalization analysis to estimate the contribution of the short-distance physics. This is done using two different prescriptions, the popular $\\overline{MS}$ scheme, valid only for perturbative calculations, and the PDS scheme, used in EFTs for loosely-bound systems and intrinsically non-perturbative. We show that, without a short-distance contact interaction, the observables become very dependent on the regularization scale, therefore demanding proper renormalization. We include two short-distance contact terms, one for each decay channel, and impose the renormalization condition within both $\\overline{MS}$ and PDS schemes. We obtain the behavior of the contact term with the renormalization scale $\\mu$, which can be useful in guiding models for the short-distance part. We note, however, distinct behaviors between $\\overline{MS}$ and PDS. Both also lead to lower limits in the decay widths that could, in principle, be tested experimentally. / In this thesis we study radiative decays of the exotic meson X(3872) into $J/ \\psi \\gamma$ and $\\psi(2S) \\gamma$ using an effective field theory framework. Assuming the exotic meson to be primarily a molecular state of the mesons $D$ and $ \\bar{D}^{*}$, we perform a renormalization analysis to estimate the contribution of the short-distance physics. This is done using two different prescriptions, the popular $\\overline{MS}$ scheme, valid only for perturbative calculations, and the PDS scheme, used in EFTs for loosely-bound systems and intrinsically non-perturbative. We show that, without a short-distance contact interaction, the observables become very dependent on the regularization scale, therefore demanding proper renormalization. We include two short-distance contact terms, one for each decay channel, and impose the renormalization condition within both $\\overline{MS}$ and PDS schemes. We obtain the behavior of the contact term with the renormalization scale $\\mu$, which can be useful in guiding models for the short-distance part. We note, however, distinct behaviors between $\\overline{MS}$ and PDS. Both also lead to lower limits in the decay widths that could, in principle, be tested experimentally.
| Identifer | oai:union.ndltd.org:IBICT/oai:teses.usp.br:tde-06012016-172040 |
| Date | 04 December 2015 |
| Creators | Daniel Alberto Stanischesk Molnar |
| Contributors | Renato Higa, Airton Deppman, Kanchan Pradeepkumar Khemchandani |
| Publisher | Universidade de São Paulo, Física, USP, BR |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da USP, instname:Universidade de São Paulo, instacron:USP |
| Rights | info:eu-repo/semantics/openAccess |
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