Miguel Medina Jaime

In this paper we investigate the production of pentaquark states in the photon -- proton interactions present in hadronic collisions at the RHIC and LHC. We consider two phenomenological models for the $J/\Psi$ photoproduction that consider the presence of the $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$ resonances in the $s$ -- channel of the $\gamma p \rightarrow J/\Psi p$ reaction. The rapidity distribution is estimated for $pA$ collisions at the RHIC and LHC. Predictions for $pPb$, $Pb \, Ar$ and $Pb \,He$ fixed -- target collisions at the LHC are also presented. We demonstrate that the experimental analysis of the $J/\Psi$ photoproduction in fixed -- target collisions can provide complementary and independent checks on these states, and help to understand their underlying nature.

In this paper, we estimate the production of dimuons (${\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$) in exclusive photon-photon ($\ensuremath{\gamma}\ensuremath{\gamma}$) and diffractive Pomeron-Pomeron ($I\phantom{\rule[-0.0ex]{-0.3em}{0.0ex}}PI\phantom{\rule[-0.0ex]{-0.3em}{0.0ex}}P$), Pomeron-Reggeon ($I\phantom{\rule[-0.0ex]{-0.3em}{0.0ex}}PI\phantom{\rule[-0.0ex]{-0.3em}{0.0ex}}R$), and Reggeon-Reggeon ($I\phantom{\rule[-0.0ex]{-0.3em}{0.0ex}}RI\phantom{\rule[-0.0ex]{-0.3em}{0.0ex}}R$) interactions in $pp$ collisions at the LHC energy. The invariant mass, rapidity, and tranverse momentum distributions are calculated using the forward physics Monte Carlo (FPMC), which allows us to obtain realistic predictions for the dimuon production with two leading intact hadrons. In particular, predictions taking into account the CMS and LHCb acceptances are presented. Moreover, the contribution of the single diffraction for the dimuon production also is estimated. Our results demonstrate that the experimental separation of these different mechanisms is feasible. In particular, the events characterized by pairs with large squared transverse momentum are dominated by diffractive interactions, which allows us to investigate the underlying assumptions present in the description of these processes.

The exclusive $\rho$, $\omega$ and $J/\Psi$ photoproduction in fixed - target collisions at the LHC is investigated. We estimate, for the first time, the rapidity and transverse momentum distributions of the vector meson photoproduction in $p He$, $p Ar$, $Pb He$ and $Pb Ar$ fixed - target collisions at the LHC using the STARlight Monte Carlo and present our results for the total cross sections. Predictions for the kinematical range probed by the LHCb detector are also presented. Our results indicate that the experimental analysis of this process in fixed - target collisions at the LHC is feasible. Such future analysis will probe the QCD dynamics in a kinematical range complementary to that studied in the collider mode.

Over the past years, the LHC experiments have reported experimental evidence for processes associated to photon-photon and photon-hadron interactions, showing their potential to investigate the production of low- and high-mass systems in exclusive events. In the particular case of the photoproduction of vector mesons, the experimental study of this final state is expected to shed light on the description of the QCD dynamics at small values of the Bjorken-$x$ variable. In this paper, we extend previous studies for the exclusive $J/\mathrm{\ensuremath{\Psi}}$ and $\mathrm{\ensuremath{\Upsilon}}$ photoproduction in $pp$ collisions based on the nonlinear QCD dynamics by performing a detailed study of the final-state distributions that can be measured experimentally at the LHC and at a future circular collider. Predictions for the rapidity and transverse momentum distributions of the vector mesons and of final-state dimuons are presented for $pp$ collisions at $\sqrt{s}=7$, 13, and 100 TeV.

Over the past years the LHC experiments have reported experimental evidences for processes associated to photon-photon and photon-hadron interactions, showing their potential to investigate the production of low- and high-mass systems in exclusive events. In the particular case of the photoproduction of vector mesons, the experimental study of this final state is expected to shed light on the description of the QCD dynamics at small values of the Bjorken-$x$ variable. In this paper we extend previous studies for the exclusive $J/Ψ$ and $Υ$ photoproduction in $pp$ collisions based on the nonlinear QCD dynamics by performing a detailed study of the final state distributions that can be measured experimentally at the LHC and at the Future Circular Collider. Predictions for the rapidity and transverse momentum distributions of the vector mesons and of final-state dimuons are presented for $pp$ collisions at $\sqrt{s} =$ 7, 13, and 100 TeV.

A producao exclusiva de bosons Z e um processo difrativo, teoricamente representado pela troca de um objeto com os numeros quânticos do vacuo (pomeron- IP), o qual pode ser tratado no modelo padrao no enfoque do mecanismo de dipolo, via fotoproducao. A carateristica principal deste tipo de processo e que os dois protons emergem intactos apos a colisao com momentum transverso pequeno. Assim, os protons sao espalhados muito frontais e escapam a deteccao., restandonos como criterio de e. Espera-se , onde um proton irradia um foton virtual, o qual flutua para um par quark anti-quark os quais sao espalhados elasticamente pela troca de dois gluons emergentes do outro proton, e se materializa num boson Z. Alem disso, os dois protons emergem intactos apos a colisao com momentum transverso pequeno, assim protons sao espalhados muito frontais e escapam a deteccao. Portanto, o criterio usado para a identificacao de eventos exclusivos de bosons Z decaindo em par muons e o numero de adicionais no vertice, mas ainda resta a possibilidade de haver uma dissociacao de pelo menos um dos protons. Neste caso, a medida da secao de choque respectiva sera contaminada. Sao expostos tres diferentes metodos para a pre-selecao des eventos contendo eventos exclusivos. A estrategia de analise proposta para selecionar eventos exclusivos e baseada no decaimento de bosons Z em pares  caraterizados por grande momento transverso, para o qual exploramos muons em uma regiao cinematica de momento transverso Pt(?)>20 GeV, massa invariante M(????)>40 GeV/c² e pseudo-rapidez |?|<2,5. Adicionalmente a estes cortes, exigimos zero tracos extras no vertice e, por ultimo que o par de muons sejam back-to-back com balanco no Pt. Nesta Tese se apresenta um estudo da producao exclusiva de bosons Z em colisoes proton-proton para energias de centro de massa igual a ?s=7 TeV no experimento CMS/LHC. Esta analise foi feita usando simulacoes para processos de Drell-Yan, fotoproducao de muons e dados coletados pelo detector CMS de colisoes proton-proton com ?s=7 TeV durante o ano de 2011, correspondendo a uma luminosidade integrada de 5,09 fb?¹. Nenhum excesso significante de sinal foi extraido nas producoes exclusivas de fazemos uma estimativa de eventos esperados nas producoes exclusiva e bosons. Nenhum candidato a boson Z exclusivo foi possivel de observar, isto devido ao fato da baixa estatistica e o enorme background proveniente de processos de Drell-Yan., que mesmo sendo processos nao exclusivos contaminarem nossa amostra de dados devido ao fato de que os protons escapam de nossa deteccao e o unico criterio de exclusividade e o de o numero de extras no vertice do evento seja igual a zero, mas devido a que os protons podem dissociar sim ser detetados e nos foi impossivel dete devido a que assim protons sao espalhados muito frontais e escapam a deteccao. Entretanto, a secao de choque para processos de producao exclusiva de bosons Z e encontrada a ser ?excl(Z?????)<13,3 fb para um nivel de confianca de 95%. Este e o primeiro resultado preliminar para este tipo de processo na escala de energia de 7 TeV, onde cabe destacar que este limite foi melhorado com respeito a resultados publicados pela colaboracao CDF para ?s = 1,9 TeV