Exclusive photoproduction of excited quarkonia in ultraperipheral collisions

In this paper, we discuss the exclusive photoproduction of ground and excited states of $\psi(1S,2S)$ and $\Upsilon(1S,2S)$ in ultraperipheral collisions (UPCs). Using the potential model in order to obtain the vector meson wave function, we find a good agreement of our calculations with data from the LHC and HERA colliders for $J/\psi (1S,2S)$ and $\Upsilon(1S)$ in $\gamma p$ collisions. We extend the calculations to the nuclear target case applying them to $AA$ UPCs with the use of the shadowing and finite coherence length effects fitted to the data. Our results are compared to the recent LHC data, in both incoherent ($J/\Psi(1S)$ at 2.76 TeV) and coherent ($J/\Psi(1S)$ at 2.76 and 5.02 TeV) processes. We also show the corresponding predictions for the excited states, in the hope that future measurements could provide more detailed information about the vector meson wave functions and nuclear effects.Comment: 21 pages, 7 figs, revised versio

Exclusive photo- and electroproduction of excited light vector mesons via holographic model

In this paper, we study total and differential observables of electro- and photoproduction of light $\rho$, $\omega$ and $\phi$ mesons as functions of the center-of-mass energy of the $\gamma p$ collision and momentum transfer squared $|t|$. The corresponding vector mesons wave functions have been computed in the framework of relativistic AdS/QCD holographic approach. A satisfactory description of all available data on ground-state $\rho(1S)$, $\omega(1S)$ and $\phi(1S)$ mesons production cross sections has been achieved in the color dipole picture. Finally, the key observables of excited $\rho(2S)$, $\omega(2S)$ and $\phi(2S)$ states production in $\gamma^{(*)} p$ collisions have been presented here using a common wave function formalism. This study reveals a large theoretical uncertainty coming from the modeling of the partial dipole amplitude in the nonperturbative kinematical domain. Hence, the latter could benefit from future measurements of photoproduction of the excited states

Fotoprodução exclusiva de quarkônios pesados em colisões ultraperiféricas

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Graduação em Física, Florianópolis, 2020.Neste trabalho, discutimos a fotoprodução exclusiva de estados fundamentais e excitados dos mésons vetoriais J/?(1S, 2S) e ?(1S, 2S) em colisões ultraperiféricas (UPCs) entre íons e prótons. Para as funções de onda do fóton que se desdobra no par quark-antiquark utilizamos as já bem conhecidas e utilizadas na literatura funções de onda nas variáveis do cone de luz. Para a interação do dipolo de quarks com o íon, utilizamos as seções de choque obtidas fenomenologicamente GBW e KST, e discussões acerca do limite não perturbativo da QCD são desenvolvidas. Posteriormente, utilizamos os modelos de potenciais entre quarks, bem como efeitos de spin dos mesmos, para obter as funções de ondas dos mésons pesados através das equações de Schrödinger no regime não relativístico. Encontramos uma boa concordância entre os nossos cálculos e os dados obtidos dos colisores de LHC e HERA para J/?(1S, 2s) e ?(1S) em colisões ?p. Utilizando o fluxo de fótons provindo do método de Weizsäcker-Williams e a seção de choque de fotoprodução nuclear da teoria de Glauber-Gribov, somos capazes de estender a análise para o caso nuclear, e comparar os resultados obtidos com os aceleradores de partículas. Das produções nucleares, dois casos são possíveis de serem obtidos, o caso em que o núcleo alvo permanece intacto (produção coerente) e o caso em que o mesmo se excita ou quebra para um estado qualquer (produção incoerente). Dois efeitos de grande importância são apresentados no caso de colisões ultraperiféricas nucleares (AA UPCs), chamados de sombreamento de glúons e comprimento de coerência finita. Nossos resultados são comparados com os dados recentes do aceleradores LHCb, CMS e ALICE para o caso incoerente (J/?(1S) para 2.76 TeV) e para o caso coerente (J/?(1S, 2S) para 2.76 e 5.02 TeV). Também mostramos as predições para os estados que ainda não possuem dados, no aguardo que futuras medições tragam uma informação mais detalhada sobre as funções de onda dos mésons vetoriais e sobre os efeitos nucleares.Abstract: In this work, we discuss the exclusive photoproduction of ground and excited states of ?(1S, 2S) and ?(1S, 2S) in ultraperipheral collisions (UPCs) of ions and protons. For the photon wave functions that fluctuates to the pair quark antiquark we use the well known and used in literature wave functions in the light-cone variables. For the interaction of the quarks dipole with the target, it is used the dipole cross sections obtained phenomenologically GBW and KST, and discussions about the non-perturbative QCD limit are made. Furthermore, using the potential models in order to obtain the vector meson wave function, we find a good agreement of our calculations with data from the LHC and HERA colliders for J/?(1S, 2S) and ?(1S) in ?p collisions. Using the photon flux from the Weizsäcker-Williams method and the Glauber-Gribov photoproduction cross section in the nuclear regime, we are able to obtain the total nuclear cross sections and compare them with the data from accelerators. For the nuclear processes, two cases are important to understand: the one where the nucleus stays intact (coherent production) and the one in which it breaks or is excited (incoherent production) after the collision. Two effects are also discussed in this work and are important in the calculations to the nuclear target case: the gluon shadowing and the finite coherence length. Our results are compared to the LHCb, CMS and ALICE data, in both incoherent (J/?(1S) at 2.76 TeV) and coherent (J/?(1S, 2S) at 2.76 and 5.02 TeV) processes. We also provide the corresponding predictions for the excited states of charmonia and bottomonia, in the expectation that future measurements could provide a more detailed information about the vector meson wave functions and the nuclear effects

Produção exclusiva e fotoprodução nuclear de mésons vetoriais leves via formalismo de dipolos de cor

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Graduação em Física, Florianópolis, 2025.Nesta tese, tratamos da produção exclusiva de mésons vetoriais leves, ?, ? e ? e seus estados excitados. Começamos em colisões ep calculando as seções de choque totais e diferenciais, com dependência na energia de centro de massa da colisão µp e do momento transferido ao quadrado t, respectivamente. Uma descrição satisfatória dos dados disponíveis de HERA de produção exclusiva dos estados fundamentais ?(1S), ?(1S) e ?(1S) foi obtida por meio dos modelos de dipolos de cor GBW, bsat e BCGC e das funções de onda holográficas dos mésons vetoriais, obtidas a partir do formalismo de AdS/QCD. O modelo holográfico nos permite fazer predições para os estados excitados dos mésons vetoriais leves, ?(2S), ?(2S) e ?(2S), através de um formalismo em comum. No regime não perturbativo, mostra-se uma importante incerteza teórica advinda das diferentes parametrizações dos modelos de dipolos de cor. Portanto, estes últimos podem se beneficiar por meio de futuros dados de fotoprodução de estados excitados, especialmente nos regimes de grandes dipolos. Considerando o sucesso da descrição dos dados de µp, estendemos a análise para o caso de fotoprodução nuclear de mésons vetoriais leves. A aplicação do formalismo de fotoprodução nuclear é motivada pelos recentes dados obtidos de PbPb ? ?(1S)PbPb no LHC. Para tal, empregamos o modelo de Glauber-Gribov para o espalhamento nuclear, bem como o fluxo de fótons de Weizsäcker-Williams, gerado pelos núcleos de chumbo. Conseguimos a descrição dos dados considerando um sombreamento de glúons efetivo RG = 0.85, compatível com o dado de espalhamento profundamente inelástico FA2 em pequeno Q2 = (M?/2)2 ? 0.15 GeV2 da colaboração E665 e com os dados de fotoprodução de ?(1S). Considerando o mesmo fator de RG = 0.85, calculamos nossas predições para a fotoprodução dos demais mésons vetoriais ?(2S), ?(1S, 2S) e ?(1S, 2S).Abstract: In this thesis, we address the exclusive production of light vector mesons, ?, ? and ?, and their excited states. For these, we calculate the total and differential cross sections, as functions of the center-of-mass energy of the µp collision and the squared momentum transfer t, respectively. A satisfactory description of the available data for exclusive µp production of the ground states ?(1S), É(1S), and ?(1S) was obtained using the GBW, bSat, and BCGC color dipole models and employing the holographic wave functions of the vector mesons derived from the AdS/QCD formalism. The use of the holographic formalism enables us to make predictions for the excited states of the light vector mesons ?(2S), ?(2S), and ?(2S) through a common framework. In the non-perturbative regime, a significant theoretical uncertainty arises from the different parametrizations of the dipole models. Therefore, these models may benefit from future data on the photoproduction of excited states, especially in the large dipole regime. Considering the description of the data in the µp case, the analysis is extended to the nuclear photoproduction of light vector mesons. This extension is motivated by the recent availability of data for PbPb ? ?(1S)PbPb at the LHC. To this end, we employ the Glauber-Gribov formalism for nuclear scattering, as well as the Weizsäcker-Williams model for the photon flux generated by lead nuclei. We achieved a description of the data by considering a gluon shadowing effect of RG = 0.85, consistent with the deeply inelastic scattering FA2 data at low Q2 ? (M?/2)2 from the E665 collaboration and with the photoproduction data of ?(1S). Using the same factor of RG = 0.85, we calculated our predictions for the photoproduction of the other vector mesons ?(2S), ?(1S, 2S), and ?(1S, 2S)

Coherent photoproduction of light vector mesons off nuclear targets in the dipole picture

We study the coherent photoproduction of light vector mesons in Pb-Pb collisions in the framework of color dipole approach. We employ the Glauber–Gribov formalism supplemented by an effective suppression factor RG accounting for the gluon shadowing correction. We adjust the latter to reproduce the deep inelastic structure function F2 (E665) and ρ meson photoproduction (ALICE) data. We achieve a good description of the available data points with RG=0.85 at scale Mρ2/4=0.15 GeV2. In addition, employing this suppression factor, we present predictions for coherent ρ(2S), ω(1S,2S) and ϕ(1S,2S) photoproduction observables using the holographic vector meson wave functions

Momentum transfer squared dependence of exclusive quarkonia photoproduction in ultraperipheral collisions

We study fully differential quarkonia photoproduction observables in ultraperipheral collisions as functions of momentum transfer squared. We employ the dipole picture of the QCD part of the scattering with proton and nucleus targets, with the projectile being a quasireal photon flux emitted by an incoming hadron. We analyze such observables for ground J/ψ, (1S) and excited ψ′, (2S) states whose light-front wave functions are obtained in the framework of an interquark potential model incorporating the Melosh spin transformation. Two different low-x saturation models, one obtained by solving the Balitsky-Kovchegov equation with the collinearly improved kernel and the other with a Gaussian impact-parameter-dependent profile, are used to estimate the underlined theoretical uncertainties of our calculations. The results for the proton target and with charmonium in the final state are in agreement with the available HERA data, while in the case of the nucleus target we make predictions for γA and AA differential cross sections at different W and at s=5.02 TeV, respectively