arXiv subjects

Victor P. Goncalves

Publications and source records attributed to Victor P. Goncalves.

At least 19 recordsLinked to original sources

arXiv2026

Neutrino trident process at a muon collider

A TeV-scale muon collider enables the production of a highly collimated high-energy neutrino flux by muon decay in the straight sections of the collider ring. Recent studies have demonstrated that these neutrinos can be used for high-precision measurements in neutrino physics with a dedicated far-forward neutrino detector. In this study, we investigate the potentiality of the muon collider to discover the rare neutrino trident process, which is characterized by the fusion between a weak boson from the neutrino and a photon from the Coulomb field of the nucleus target. Our results indicate large neutrino trident rates per year [$\mathcal{O}(10^3)$] in a baseline 10 kg neutrino detector for a configuration of different flavour pairs of charged leptons in the final state, which will allow high-precision tests of the Standard Model and searches for New Physics. As a first example, we investigate the impact of the a new gauge boson $Z'$, as predicted by the $L_μ- L_τ$ model, and derive the projected sensitivity to this new gauge boson. Our findings show that a neutrino detector at a muon collider will significantly extend the current excluded regions of the parameter space.

hep-ph↗

arXiv2026

Exclusive photoproduction of vector toponium within the color dipole picture

The exclusive photoproduction of the toponium vector meson ($ψ_t$) is investigated within the color dipole model. The overlap function between the light-cone wave function of the vector toponium state and the photon wave function is estimated using the Boosted Gaussian approach. Considering the dominance of small dipoles, the dipole-proton scattering amplitude is estimated in terms of parton distribution functions, and predictions for the photoproduction cross-section in the energy range of the proposed Large Hadron electron Collider (LHeC) are presented. Moreover, the cross-sections and rapidity distributions for the exclusive $ψ_t$ photoproduction in ultraperipheral proton-proton and proton - nucleus collisions at the Large Hadron Collider (LHC) and Future Circular Collider (FCC) energies are calculated. We find that exclusive $ψ_t$ photoproduction is, in principle, feasible in ultraperipheral $pp$ collisions at the FCC-hh.

hep-ph↗

arXiv2026

Double D meson production in ultraperipheral $pp$, $pPb$ and $PbPb$ collisions

The production of a $D^+ D^-$ pair by photon - photon interactions at the Large Hadron Collider (LHC) is investigated considering ultraperipheral proton - proton ($pp$), proton - lead ($pPb$) and lead - lead ($PbPb$) collisions. Assuming that the scattering amplitude for the $γγ\rightarrow D^+ D^-$ process can be described by the Brodsky - Lepage formalism in the heavy - quark approximation, we derive the associated differential distributions and total cross - sections. In particular, in addition to the rapidity and transverse momentum distributions, usually presented in the literature, we also present predictions for the total transverse momentum and momentum imbalance distributions. Our results indicate that a future experimental analysis of this final state is, in principle, feasible during the high luminosity run of LHC.

hep-ph↗

arXiv2026

Probing the neutrino trident process using the Scattering and Neutrino Detector at HL-LHC and SHiP

Neutrino trident scattering is a rare process in the Standard Model characterized by two charged leptons in the final state. In this work, we investigate the possibility of probing the neutrino trident process using the Scattering and Neutrino Detector (SND) at the Large Hadron Collider during its high - luminosity run (HL - LHC). In addition, we present, for the first time, the predictions for the neutrino trident scattering at SHiP beam - dump experiment, where a similar detector is expected to be installed. We demonstrate that these two experiments probe the process in a complementary energy range. Assuming the upgraded detector configuration, we estimate the cross-sections associated with all possibles leptonic final states in coherent and incoherent processes. The corresponding number of neutrino trident scatterings in the SND at HL-LHC and SHiP are presented. Our results indicate that this process can be observed in these forthcoming experiments for some specific combinations of leptons in the final state.

hep-ph↗

arXiv2026

Gamma-ray production in the cosmic-ray -- dark matter scattering as a probe of the axion-like particle -- proton interaction

The production of very-high-energy (VHE, $E_γ \gtrsim 100$ GeV) gamma rays resulting from the scattering of high-energy cosmic-ray protons off axion-like particles (ALPs) populating the dark matter halo of the Milky Way is investigated. By employing the latest instrument response functions for current and future facilities, we demonstrate that ground-based VHE gamma-ray observatories, such as H.E.S.S., CTAO, and SWGO, provide a promising and complementary avenue to probe the yet uncharted ALP-proton coupling $g_{ap}$. Our results show that these experiments can reach sensitivity to couplings above $10^{-2}$ in the $1 - 10^{8}$ eV ALP mass range, a region that remains largely unexplored by supernova and neutron star cooling observations. Interestingly, we demonstrate that this search channel is capable of probing QCD axion dark matter models, assuming two benchmark models for it: the Kim-Shifman-Vainshtein-Zakharov (KSVZ) Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) models, specifically within the MeV mass range. These findings highlight the potential of VHE gamma-ray astronomy to provide unique constraints on the interaction between ALPs and the baryonic sector.

hep-ph↗

arXiv2026

Probing the pion gluon distribution at small-$x$ in photon-induced interactions at LHC

In this paper we propose the analysis of the heavy quark photoproduction associated with a leading neutron in hadronic collisions at the LHC as an alternative to probe the pion gluon distribution in a kinematical range not covered by previous experiments. We perform an exploratory study of the charm and bottom photoproduction associated with a leading neutron in proton-proton ($pp$) and proton-lead ($pPb$) collisions, and present calculations for the rapidity distributions and cross-sections. Our predictions indicate that experimental studies of these processes are feasible, and that a future measurement of this final state will be useful to constrain the pion gluon distribution at small values of the Bjorken $x$ variable and to improve our understanding of the pion structure.

hep-ph↗

arXiv2026

Inclusive heavy meson photoproduction in $pPb$ and $PbPb$ collisions

The inclusive photoproduction of heavy mesons in ultraperipheral $pPb$ and $PbPb$ collisions at the LHC energies is investigated considering the color dipole $S$-matrix formalism and assuming distinct models for the unintegrated gluon distribution, based on different assumptions for the description of the QCD dynamics. In particular, predictions for the $B^0$-meson photoproduction are presented here for the first time. The study of the $D^0$-meson photoproduction is revisited by estimating the impact of the treatment of the heavy charm fragmentation on the predictions and extended for $pPb$ collisions. Moreover, the contribution associated with the $b \rightarrow D^0$ transition is estimated. Our results indicate that a future experimental analysis of the heavy meson photoproduction will provide important constrains on the description of the hadronic structure at high energies.

hep-ph↗

arXiv2026

Muon trident process at far-forward LHC detectors

The electromagnetic production of a dilepton pair in the muon - ion scattering, usually denoted muon trident process, is investigated considering the feasibility of studying processes induced by muons at LHC using its far-forward detectors. The total and differential cross - sections are estimated taking into account of the Bethe-Heitler and bremsstrahlung channels, and predictions for the event rates expected for muon - tungsten ($μW$) collisions at the LHC energies are presented. Our results indicate that the observation of the muon trident process is feasible at FASER$ν$. In particular, our results indicate that the electromagnetic production of $τ^+ τ^-$ pairs in the $μW$ scattering can, in principle, be observed for the first time ever at the LHC. In addition, we present our predictions for the production of QED bound states. Finally, results for the trident process at the FASER$ν$2 detector are also presented.

hep-ph↗

arXiv2025

Exclusive vector-toponium photoproduction in hadronic collisions

An exploratory study of the exclusive production of a vector - toponium $ψ_t$ state by photon - hadron interactions is performed considering proton - proton and proton - nucleus collisions at the Large Hadron Collider (LHC) and Future Circular Collider (FCC) energies. The scattering amplitude is calculated using the $k_T$ - factorization formalism assuming that the vector - toponium state can be described by a Gaussian light-cone wave function and considering different models for the unintegrated gluon distribution. Predictions for the rapidity distributions and total cross - sections are presented. Our results indicate that the experimental measurement of this final state will be very difficult for the expected integrated luminosities at the LHC and FCC.

hep-ph↗

arXiv2025

Investigating nuclear effects in lepton-ion DIS at the LHC

Recent studies have demonstrated that the far-forward physics program of the Large Hadron Collider (LHC) can be useful to probe the hadron structure with GeV-TeV neutrinos and muons. In particular, these studies indicate that the measurement of the muon-ion and neutrino-ion cross-sections by the same experiment is feasible. In this paper, we investigate the impact of nuclear effects on the muon-tungsten ($μW$) and neutrino-tungsten ($νW$) deep inelastic scattering (DIS) events at FASER$ν$ and its proposed upgrade FASER$ν2$. We estimate the rates associated with the inclusive cross-sections and for events with a charm tagged in the final state considering different parameterizations for the nuclear parton distribution functions. These results point out that muon and neutrino-induced interactions probe complementary kinematical ranges and that a simultaneous analysis of associated events will allow to test the universality (or not) of the nuclear effects. Moreover, we propose the study of the ratio between the charm tagged and inclusive events in order to discriminate between the distinct modeling of the nuclear effects at small-$x$. Our results indicate that a future experimental reconstruction of $μW$ and $νW$ DIS events at the LHC is a promising way to improve our understanding of nuclear effects and decrease the current uncertainties in parton distribution functions.

hep-ph↗

arXiv2025

Investigating the exclusive toponium production at the LHC and FCC

An exploratory study of the exclusive toponium production in $pp$, $pPb$ and $PbPb$ collisions at the center - of - mass energies of the Large Hadron Collider (LHC) and Future Circular Collider (FCC) is performed. Assuming that the toponium is a pseudoscalar $t\bar{t}$ state, we consider its exclusive production by photon and gluon - induced interactions. Results for the total cross - sections and associated rapidity distributions are presented, and the number of events at the LHC and FCC are estimated.

hep-ph↗

arXiv2025

Deep-Inelastic Scattering at TeV Energies with LHC Muons

The LHC far-forward experiments FASER and SND@LHC have pioneered the detection of TeV-energy neutrinos produced in hard-scattering proton-proton collisions at the LHC. In addition to neutrinos, an intense flux of TeV-energy muons reaches these detectors, representing a dominant background for both neutrino studies and beyond the Standard Model searches. Here we demonstrate that this forward muon flux enables a comprehensive neutral-current deep-inelastic scattering (DIS) program at FASER with a strong kinematical overlap with the Electron Ion Collider. For the Run 3 luminosity of $\mathcal{L}_{\rm pp}=250$~fb$^{-1}$, more than $10^5$ inclusive muon DIS events, of which up to $10^4$ from charm production, are expected at FASER$ν$. As a representative application, we demonstrate the sensitivity of muon DIS at FASER$ν$ to probe the (intrinsic) charm content of the proton at large-$x$. We also provide predictions for event yields of muon DIS for future FASER runs and for the proposed Forward Physics Facility.

hep-ph↗

arXiv2025

Photonuclear Tomography in Ultraperipheral Heavy-Ion Collisions

We present a theoretical investigation of photonuclear tomography as a novel technique for probing the internal structure of nuclei. In this approach, ultraperipheral heavy-ion collisions (UPCs) serve as a source of intense fluxes of virtual photons, which induce coherent production of vector mesons. By analyzing the probabilities and cross sections of these photon-induced processes, we propose a methodology for reconstructing the spatial distribution of nucleons within the nucleus. Our framework provides a systematic way to access information on the nuclear geometry probed in UPCs, offering new opportunities for studies of nuclear structure using particle production as a probe. Numerical calculations for selected examples illustrate the feasibility and potential of this method.

nucl-th↗

arXiv2025

Photoproduction of heavy vector mesons in peripheral $PbPb$ collisions at the Large Hadron Collider

A comprehensive analysis of the photoproduction of $J/Ψ$ and $Υ$ mesons in peripheral $PbPb$ collisions at the center - of - mass energies of the Large Hadron Collider (LHC) is performed, considering distinct assumptions for the modeling of the nuclear photon flux, photon - nucleus cross - section, overlap function and dipole - proton scattering amplitude. The comparison of these predictions with the ALICE data is also performed. Our results indicate that a detailed analysis of the production of both mesons will be very useful to improve the description of photon - induced processes in peripheral collisions.

nucl-ex↗

arXiv2025

Light-by-Light scattering in ultraperipheral heavy ion collisions: Estimating inelastic contributions

The current state-of-the-art theoretical estimations lead to cross-sections for $AA \to γγAA$ which are somewhat smaller than the measured ones by the ATLAS and CMS Collaborations, which motivates the searching and calculation of subleading corrections disregarded in these previous studies. In this paper, we estimate for the first time the contribution of inelastic channels to the Light-by-Light (LbL) scattering in ultraperipheral collisions of heavy ions (UPHICs), in which one or both of the incident nuclei dissociate ($A A \to γγX Y$ where $X, Y = A, A'$) due to the photon emission. These new mechanisms are related to extra emissions that are rather difficult to identify at the LHC and may be misinterpreted as enhanced $γγ\to γγ$ scattering compared to the Standard Model result. We include processes of coupling of photons to individual nucleons (protons and neutrons) in addition to coherent coupling to the whole nuclei (called standard approach here). Both elastic (nucleon in the ground state) and inelastic (nucleon in an excited state) in the couplings of photons to nucleons are taken into account. The inelastic nucleon fluxes are calculated using CT18qed photon in nucleon PDFs. The inelastic photon fluxes are shown and compared to standard photon fluxes in the nucleus. In addition, we show the ratio of the inelastic corrections to the standard contribution as a function of diphoton invariant mass and photon rapidity difference. We find that for the ATLAS acceptance region the inelastic corrections grow with $M_{γγ}$ and rapidity difference. Our results indicate that the inelastic contributions can be of the order of 20-40 \% of the traditional (no nuclear excitation) predictions. Uncertainties due to factorization scale choice are quantified.

hep-ph↗

arXiv2025

Dilepton angular distributions in the color-dipole $S$-matrix framework

The dilepton production at forward rapidities in hadronic collisions at the LHC energies is considered and the helicity density matrix elements of gauge bosons that enter the Drell--Yan angular coefficients associated with the gauge boson decay ($G = γ^*, Z^0, W$) are derived using the color-dipole $S$ - matrix framework. We show results for $pp$ collisions at $\sqrt{s} = 14$ TeV for the nonvanishing helicity density matrix elements in the rapidity range of $2.0 \le y \le 4.0$ of the gauge boson. We consider different models for the proton unintegrated gluon distributions, among others a solution of the Balitsky--Kovchegov equation. We compare the associated predictions with those obtained disregarding the non-linear term in the evolution equation. In addition, the Lam--Tung relation is discussed.

hep-ph↗

arXiv2025

Sensitivity of the neutrino transmission coefficient at high energies to the Earth's density profile

The flux of atmospheric and astrophysical neutrinos measured in UHE neutrino detectors is strongly dependent on the description of the propagation and absorption of the neutrinos during the passage through Earth to the detector. In particular, the attenuation of the incident neutrino flux depends on the details of the matter structure between the source and the detector. In this paper, we will investigate the impact of different descriptions for the density profile of Earth on the transmission coefficient, defined as the ratio between the flux measured in the detector and the incoming neutrino flux. We will consider five different models for the Earth's density profile and estimate how these different models modify the target column density and transmission coefficients for different flavors. The results are derived by solving the cascade equations taking into account the NC interactions and tau regeneration. A comparison with approximated solutions is also presented. Our results indicated that the predictions are sensitive to the model considered for the density profile, with the simplified three layer model providing a satisfactory description when compared with the PREM results.

hep-ph↗

arXiv2025

Investigating the inclusive $D^0$ photoproduction in ultraperipheral $PbPb$ collisions at the Large Hadron Collider

The inclusive $D^0$ photoproduction in $PbPb$ collisions at the center - of - mass energies of the Large Hadron Collider (LHC) is investigated considering the color dipole $S$ - matrix approach. The analytical expressions for the differential distributions are derived in the impact parameter and transverse momentum spaces and predictions for the rapidity and transverse momentum distributions are presented considering three distinct models for the unintegrated gluon distribution of the nuclear target. In particular, we compare the predictions derived assuming a linear dynamics, with and without the inclusion of nuclear effects, with those obtained by solving the running coupling Balitsky - Kovchegov equation. A comparison of these predictions with the recent (preliminary) CMS data is also performed. Our results indicate that a detailed analysis of this observable will be very useful to improve our understanding of the strong interaction theory at high energies and in a nuclear medium.

hep-ph↗