arXiv subjects

Victor P. Gonçalves

Publications and source records attributed to Victor P. Gonçalves.

9 recordsLinked to original sources

arXiv2026

Photoproduction of $J/Ψ$ in peripheral Oxygen-Oxygen collisions

The photoproduction of $J/Ψ$ in peripheral Oxygen - Oxygen ($OO$) collisions at the Large Hadron Collider (LHC) is investigated considering distinct assumptions for the modeling of the nuclear photon flux, overlap function and dipole - proton scattering amplitude. Predictions for the associated rapidity distributions and total cross - sections are presented. Our results indicate that the experimental study of the photoproduction of $J/Ψ$ in peripheral $OO$ collisions is, in principle, feasible. In addition, they point out that the combination of the results for this final state in $OO$ collisions with those obtained for $PbPb$ collisions will allow us to derive important constraints on the description of photon - induced process at peripheral collisions.

hep-ph↗

arXiv2026

Fully charmed tetraquark production in forward rapidity $pp$ collisions at LHC and FCC energies

In this paper, we investigate the production of a fully charmed tetraquark state $T_{4c}$ in $pp$ collisions at forward rapidities through the fragmentation mechanism considering the Color Glass Condensate (CGC) formalism and the solution of the running coupling Balitsky-Kovchegov (BK) equation. The contributions of gluon - and charm - initiated processes are taken into account, and the impact of an intrinsic charm component in the proton's wave function is estimated. Predictions for the transverse momentum distribution of the $T_{4c}$ state are presented assuming different rapidities, distinct quantum numbers of the state and center-of-mass energies. Our results indicate that the higher cross-section is associated with the production of a tensor state $T_{4c}(2^{++})$, which is dominated by the gluon-initiated process. In contrast, the production of the axial-vector state $T_{4c}(1^{+-})$ is dominated by the charm-initiated process and is very sensitive to the presence (or not) of an intrinsic charm.

hep-ph↗

arXiv2025

Exclusive heavy vector meson photoproduction in $pp$ and $pPb$ collisions within the GPD approach: A phenomenological analysis

The exclusive $J/ψ$ and $Υ$ photoproduction in proton - proton ($pp$) and proton - lead ($pPb$) collisions at the LHC energies is investigated using the Generalized Parton Distribution (GDP) approach. Assuming the Goloskokov - Kroll (GK) model, we estimate the corresponding total cross - sections and rapidity distributions considering different parametrizations for the unpolarized gluon distribution of the proton. In particular, we compare the linear predictions, associated with DGLAP evolution, with those derived taking into account of the leading nonlinear corrections resulting from gluon recombination. The dependence of our predictions on the choice for the factorization scale is discussed.

hep-ph↗

arXiv2025

Looking for new strategies to probe low mass axion-like particles in ultraperipheral heavy-ion collisions at the LHC

The possibility of searching for long-lived axion-like particles (ALPs) decaying into photons is investigated in ultraperipheral $PbPb$ collisions at the Large Hadron Collider (LHC). We propose a search strategy for low mass ALPs using the LHCb and ALICE experiments. The ALP identification is performed by requiring the decay vertex be reconstructed outside the region where a primary vertex is expected, which strongly suppress the contribution associated with the decay of light mesons. We also use the fact that a fraction of the photons convert into electron-positron pairs, allowing the reconstruction of the particle decay position. We present the predictions for the pseudo - rapidity and transverse momentum distributions of the ALPs and photons. Moreover, predictions for the fiducial cross-sections, derived considering the characteristics of the ALICE and LHCb detectors, are presented for different values of the ALP mass and the ALP - photon coupling.

hep-ph↗

arXiv2024

How the QCD trace anomaly behaves at the core of twin stars?

We investigate the behavior of the dense and cold (normalized) QCD trace anomaly, $Δ$, in the interior of twin neutron stars (obtained from several sets of equations of state in agreement with modern compact-star and multimessenger data) satisfying static and dynamic stability conditions. We scan the formed twin-star parameter space in order to look for effects caused by the presence of a strong first-order phase transition connecting hadron and quark phases by means of a Maxwell construction. We found robustly that $Δ$ suffers an abrupt decrease around the transition point, even reaching large negative values ($Δ\simeq-0.35$), in marked contrast to current studies pointing out a smooth behavior with $Δ\gtrsim 0$ at all densities. Besides, we characterize the behavior of {the recently defined} conformal factor, $d_{c}$, in our four categories of twin stars for which we perform comparisons with theoretical constraints put, e.g. by Bayesian studies sometimes adjusted to agree with perturbative QCD at high densities. These analyses allow us to hypothesize modifications in the strong QCD coupling in dense nuclear matter with a strong thermodynamic discontinuity.

hep-ph↗

arXiv2024

Searches for axion-like particles via $γγ$ fusion at future $\mathrm{e}^+\mathrm{e}^-$ colliders

Opportunities for searches for axion-like particles (ALPs) coupling to photons in $\mathrm{e}^+\mathrm{e}^-$ collisions at the Future Circular Collider (FCC-ee) and International Linear Collider (ILC) are investigated. We perform a study of the photon-fusion production of ALPs decaying into two photons, $\mathrm{e}^+\mathrm{e}^- \overset{γγ}{\longrightarrow} \mathrm{e}^{+}\;a(γγ)\;\mathrm{e}^{-}$, over the light-by-light continuum background, for the planned FCC-ee and ILC center-of-mass energies and integrated luminosities. An analysis of the feasibility measurements is presented using parametrized simulations for two types of detectors. Upper limits at 95% confidence level (CL) on the cross section for ALP production, $σ(γγ\to a \to γγ)$, and on the ALP-photon coupling are obtained over the $m_a \approx 0.1$--1000 GeV ALP mass range, and compared to current and future collider searches. Production cross sections down to $σ(γγ\to a \to γγ) \approx 1$ fb (1 ab) will be probed at $m_a\approx 1$ (300) GeV, corresponding to constraints on the axion-photon coupling as low as $g_\mathrm{aγγ} \approx 2\cdot10^{-3}$ TeV$^{-1}$.

hep-ex↗

arXiv2022

The Forward Physics Facility at the High-Luminosity LHC

High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe Standard Model (SM) processes and search for physics beyond the Standard Model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF's physics potential.

hep-ex↗

arXiv2019

Longitudinal profiles of Extensive Air Showers with inclusion of charm and bottom particles

Charm and bottom particles are rare in Extensive Air Showers but the effect of its presence can be radical in the development of the Extensive Air Showers (EAS). If such particles arise with a large fraction of the primary energy, they can reach large atmospheric depths, depositing its energy in deeper layers of the atmosphere. As a consequence, the EAS observables ($X_{max}$, $RMS$ and $N_{max}$) will be modified, as well as the shape of the longitudinal profile of the energy deposited in the atmosphere. In this paper, we will modify the CORSIKA Monte Carlo by the inclusion of charm and bottom production in the first interaction of the primary cosmic ray. Results for different selections of the typical $x_F$ values of the heavy particles and distinct production models will be presented.

hep-ph↗

arXiv1999

The small $x$ nuclear shadowing at DIS

We estimate the perturbative nuclear shadowing in the nuclear structure function $F_2^A(x,Q^2)$, mainly at the kinematic region of HERA using the Glauber-Mueller approach. The contributions of the quark and gluon sectors to the nuclear shadowing are estimated. We predict that the nuclear shadowing corrections are important and that saturation of the ratio $R_1 = F_2^{A}(x,Q^2)/A F^p_2(x,Q^2)$ occurs once the shadowing in the gluon sector is considered.

hep-ph↗