arXiv subjects

G. Gil da Silveira

Publications and source records attributed to G. Gil da Silveira.

18 recordsLinked to original sources

arXiv2025

Brazilian input to the European Strategy for Particle Physics Update

The Brazilian High-Energy Physics (HEP) community has expanded remarkably since its first involvement at CERN and Fermilab in the 1980s. Its recent organization under the Brazilian Network for High-Energy Physics (RENAFAE), since 2008, has further strengthened its scientific and technological goals, particularly in detector instrumentation, computing, and industry partnerships. In 2024, Brazil became an Associate Member State of CERN, opening new opportunities for deeper engagement in accelerator and detector R&D. This input to the 2026 update of the European Strategy for Particle Physics highlights Brazil's current participation in LHC experiments as well as ongoing developments in detector and accelerator technology, and details the community's view towards future colliders. The potential for expanded scientific and industrial collaborations between Brazil and CERN is also discussed.

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arXiv2025

Brazilian Report on Dark Matter 2024

One of the key scientific objectives for the next decade is to uncover the nature of dark matter (DM). We should continue prioritizing targets such as weakly-interacting massive particles (WIMPs), Axions, and other low-mass dark matter candidates to improve our chances of achieving it. A varied and ongoing portfolio of experiments spanning different scales and detection methods is essential to maximize our chances of discovering its composition. This report paper provides an updated overview of the Brazilian community's activities in dark matter and dark sector physics over the past years with a view for the future. It underscores the ongoing need for financial support for Brazilian groups actively engaged in experimental research to sustain the Brazilian involvement in the global search for dark matter particles

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arXiv2024

Update of the Brazilian Participation in the Next-Generation Collider Experiments

This proposal outlines the future plans of the Brazilian High-Energy Physics (HEP) community for upcoming collider experiments. With the construction of new particle colliders on the horizon and the ongoing operation of the High-Luminosity LHC, several research groups in Brazil have put forward technical proposals, covering both hardware and software contributions, as part of the Brazilian contribution to the global effort. The primary goal remains to foster a unified effort within the Brazilian HEP community, optimizing resources and expertise to deliver a high-impact contribution to the international HEP community.

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arXiv2023

Double charmed meson production in $pp$ and $pA$ collisions at the LHC within the dipole approach in momentum representation

A study of double charmed meson production in proton-proton and proton-nucleus collisions at the LHC energies is performed. Based on the color dipole formalism developed in the transverse momentum representation and the double parton scattering mechanism, predictions are made for the transverse momentum differential cross section for different pairs of $D$-mesons. The theoretical results consider the center-of-mass energy and forward rapidities associated to the measurements by the LHCb Collaboration. The results considering different unintegrated gluon distributions are presented and compared to data and predictions for proton-nucleus collisions are provided.

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arXiv2023

Searching for a Leptophilic Z' and a 3-3-1 symmetry at CLIC

We derive the discovery potential of a leptophilic Z', and a Z' rising from a $SU(3) \times SU(3)_L \times U(1)_N$ symmetry at the Compact Linear Collider (CLIC), which is planned to host $e^+e^-$ collisions with 3 TeV center-of-mass energy. We perform an optimized selection cut strategy on the transverse momentum, pseudorapidity, and invariant mass of the dileptons in order to enhance the collider sensitivity. We find that CLIC can potentially reach a $5σ$ signal of a $1-3$~TeV leptophilic Z' with less than $1fb^{-1}$ of integrated luminosity. As for the Z' belonging to a 3-3-1 symmetry, CLIC will offer a complementary probe with the potential to impose $M_{Z^\prime} > 3$~TeV with $\mathcal{L}=2fb^{-1}$.

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arXiv2023

Investigation of spin-dependent dark matter in mono-photon production at high-energy colliders

Many theories about dark matter have emerged due to its strong theoretical appeal in explaining astrophysical phenomena. However, experimental and theoretical particle physics have yet not provided evidence that dark matter is part of the observable Universe. Our work aims to investigate the interaction between Standard Model (SM) fermions and different species of dark matter (DM) particles in high-energy collisions through interaction of a new massive vector mediator, Z'. The production of scalar and fermion DM pairs via fermion annihilation into the new vector boson is investigated near a resonance, where a SM signal from hard photon emission is considered as initial state radiation, namely a mono-photon production. Values of coupling constants between the DM and the SM particles are mapped in contrast to the Planck satellite data for thermal relic density DM computed in the correct framework for the relic density near a resonance, where a weaker suppression of the relic density is expected. We show for the CLIC and LHC kinematic regimes that certain mass ranges and coupling constants of these DM particles are in agreement with the expected relic density near a resonance and are not excluded by collider and astrophysical limits.

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arXiv2022

$D$-meson production in high energy $pA$ collisions within the QCD color dipole transverse momentum representation

The $D$-meson production is investigated by considering the unintegrated gluon distribution within the dipole approach in the momentum representation. We analyze the $D$-meson spectrum accounting for the effects of nonlinear behavior of the QCD dynamics which can be accordingly addressed in the dipole framework. The unintegrated gluon distribution is obtained by using geometric scaling property and the results are compared to the Glauber-Gribov framework. The absolute transverse momentum spectra and the nuclear modification ratios are investigated. Predictions are compared with the experimental measurements by the ALICE and LHCb Collaborations in $pA$ collisions for different rapidity bins.

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arXiv2021

Charmed meson production based on dipole transverse momentum representation in high energy hadron-hadron collisions available at the LHC

The production of $D$-mesons in high-energy $pp$ collisions at the LHC kinematic regime is analyzed with the dipole approach in the momentum representation. We present predictions for the $D$-meson differential cross section in terms of the transverse momentum and rapidity distributions taking into account the nonlinear behavior of the QCD dynamics. Comparison between our results and the corresponding experimental measurements reported by the ALICE and LHCb Collaborations in different rapidity bins is performed. We show that the $D$-meson production in the high energy limit can be properly addressed by using the QCD dipole transverse momentum distributions.

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arXiv2021

Non-exclusive particle production by $γγ$ interactions in $pp$ collisions at the LHC

Particle production in two-photon interactions at hadronic collisions is becoming increasingly relevant in the LHC physics programme as a way to improve our understanding of the Standard Model and search for signals of New Physics. A key ingredient for the study of these interactions in $pp$ collisions is the description of the photon content of the proton, which allow us to derive predictions for the cross sections associated to events where occur the proton dissociation (non - exclusive processes) and for those where both incident protons remain intact (exclusive processes). In this paper, a detailed comparison of the different models for the elastic and inelastic photon distributions found in the literature is presented and the current theoretical uncertainty is estimated. The impact on the invariant mass distribution for the dimuon production is analyzed. Moreover, the relative contribution of non - exclusive events is estimated and its dependence on the invariant mass of the pair is presented. We demonstrate that the predictions for production of pairs with large invariant mass is strongly dependent on the model assumed to describe the elastic and inelastic photon distributions and that the ratio between non - exclusive and exclusive cross sections present a mild energy dependence. Finally, our results indicate that a future experimental analysis of the non - exclusive events will be useful to constrain the photon content of proton.

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arXiv2020

A study on the isolated photon production in nuclear collisions at the CERN-LHC energies

An analysis of prompt photon production in high energy nuclear collisions at the LHC energy regime is performed within the parton saturation picture taking into account the updated phenomenological color dipole models. The results are confronted with the measurements made by the ALICE, ATLAS, and CMS experiments in terms of photon transverse momentum at different rapidity bins. As a result, we show that the prompt photon production exhibits distinct scalings in $AA$ events associated to geometrical properties of the collision and can be properly addressed in the color dipole formalism.

hep-ph↗

arXiv2020

The color dipole picture for prompt photon production in $pp$ and $pPb$ collisions at the CERN-LHC

A study on the prompt photon production within the QCD color dipole picture with emphasis in $pp$ and $pA$ collisions at the LHC energy regimes is performed. We present predictions for the differential cross section as a function of photon transverse momentum at different rapidity bins considering updated phenomenological color dipole models, which take into account the QCD gluon saturation physics. The results are directly compared to the recent experimental measurements provided by CMS and ATLAS Collaborations, showing a reasonable agreement in all rapidity bins with no free parameters. Special attention is given to the IPSAT model given its good description of the data in all rapidity bins from low- to high-$p_{T}$ ranges. As a result, a free-parameter approach has succeeded in describing the LHC data for prompt photon production, while new predictions for the 13-TeV data is presented in view of new data to confirm such prospect.

hep-ph↗

arXiv2020

Brazilian Participation in the Next-Generation Collider Experiments

This proposal concerns the participation of the Brazilian High-Energy Physics community in the next-generation collider experiments. As the LHC at CERN is getting ready for its third data-taking period, Run 3, with increased centre-of-mass energy at the nominal 14 TeV and upgraded detectors, the global High-Energy Physics community is converging towards the materialisation of new powerful colliders which could explore the characteristics of the Higgs boson and advance the search of physics beyond the Standard Model. This means that in the next couple of years the technical proposals for the experiments that will run in such colliders will be submitted for review, collaborations will be formed and large scale funding will be requested at different stages across the globe. Our aim is to organise a common effort from the Brazilian HEP community of optimised resources and time, in order to produce a higher impact contribution to our chosen experiment and more broadly in the field of High-Energy Physics.

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arXiv2020

Prompt photon production in high-energy $pA$ collisions at forward rapidity

Prompt photon production in hadronic collisions at the RHIC and the LHC energies is investigated within the QCD color dipole approach. Predictions for the nuclear modification factor in $pA$ collisions are evaluated based on parton saturation framework and the results are compared to the experimental measurements as a function of the photon transverse momentum at different rapidity bins. The reliability of the models is performed with the data from PHENIX, ATLAS, and ALICE Collaborations. Moreover, we show that the observed $x_T$-scaling of prompt photon production in $pp$ and $pA$ collisions can positively be addressed in the QCD color dipole formalism.

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arXiv2019

Brazilian Community Report on Dark Matter

This white paper summarizes the activities of the Brazilian community concerning dark matter physics and highlights the importance of financial support to Brazilian groups that are deeply involved in experimental endeavours. The flagships of the Brazilian dark matter program are the Cherenkov Telescope Array, DARKSIDE, SBN and LHC experiments, but we emphasize that smaller experiments such as DAMIC and CONNIE constitute important probes to dark sectors as well and should receive special attention. Small experimental projects showing the potential to probe new regions of parameter space of dark matter models are encouraged. On the theoretical and phenomenological side, some groups are devoted to astrophysical aspects such as the dark matter density profile while others explore the signature of dark matter models at colliders, direct and indirect detection experiments. In summary, the Brazilian dark matter community that was born not long ago has grown tremendously in the past years and now plays an important role in the hunt for a dark matter particle.

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arXiv2018

QCD probes at LHC

The LHC experiments have reported new results with respect to the dynamics of the strong interactions in $pp$, $p$A, and AA collisions over the past years. In proton-proton collisions, the data analyses have focused in exploring the nature of underlying events and double parton scattering at high energies. For large systems, the heavy-ion collisions have provided new insights on physics aspects related to azimuthal correlations, jet quenching, and particle production, such as antiprotons. This Letter reports the recent results from the ATLAS, CMS, and LHCb Collaborations on these various topics and highlights its relevant findings for the high-energy community.

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arXiv2018

Study on the PDF comparisons for quarkonium + $γ$ production at the LHC and FCC energies

The quarkonium plus photon production in coherent hadron-hadron interactions at the LHC is studied using the non-relativistic QCD factorization formalism. We investigate a set of kinematic distributions and compute the total cross sections for $J/Ψ+ γ$ production. Our results demonstrate the feasibility of such process in the LHC kinematic regime and explore the possibilities for the Future Circular Collider, where higher event yields can be achieved.

hep-ph↗

arXiv2016

Exclusive vector meson photoproduction at the LHC and the FCC: A closer look on the final state

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.

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arXiv2015

Probing the photon flux in the diffractive quarkonium photoproduction at LHC

In this paper we propose the study of the diffractive quarkonium photoproduction in $pp$ collisions at LHC energies to probe the photon flux associated to a ultrarelativistic proton. The total photon distribution is expected to be given in terms of the elastic and inelastic components. Distinctly from the elastic photon component which can be determined from the elastic form factors, the magnitude of the inelastic component still is an open question. We consider the current parametrizations for the photon distribution of a proton and estimate the rapidity distributions and total cross sections for the production of $J/Ψ$, $Ψ^{\prime}$ and $Υ$ at LHC energies. We demonstrate that the predictions associated to the inelastic contribution are of the same order than those associated to the elastic one. Our results implies that a dedicated experimental analysis of diffractive quarkonium photoproduction with the tagging of the two protons in the final state can be useful to constrain the magnitude of the inelastic component of the photon distribution.

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