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Daniel E. Martins

Publications and source records attributed to Daniel E. Martins.

14 recordsLinked to original sources

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↗

Probing Lorentz violating effects on the exclusive $e^+e^-$ production in ultraperipheral heavy-ion collisions

The impact of Lorentz violating (LV) terms on the exclusive $e^+e^-$ production in ultraperipheral heavy-ion collisions at the Large Hadron Collider (LHC) is investigated, considering vectorial and axial couplings. Results for the differential and total cross-sections are presented, and the sensitivity to a time-like coupling is estimated. Our results indicate that this process can improve the current upper bounds on the LV terms.

hep-ph↗

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↗

Single charged Higgs pair production in exclusive processes at the LHC

The production of a single charged Higgs boson pair by photon - photon interactions in $pp$ collisions at the LHC is investigated in this exploratory study. We focus on the exclusive production, which is characterized by intact protons and two - rapidity gaps in the final state, and assume the type - I two - Higgs - doublet model, which still allows a light charged Higgs. Assuming the leptonic $H^{\pm}\rightarrow [τν_τ]$ decay mode, we derive predictions for the transverse momentum, rapidity and invariant mass distributions of the $τ^+ τ^-$ pair for different values of the charged Higgs mass. The contributions of different background processes are also estimated. Our results indicate that the contribution of the exclusive $H^+ H^-$ production for the $[τ^{+}ν_τ][τ^{-} ν_τ]$ final state is non - negligible and can, in principle, be used to searching for a light charged Higgs.

hep-ph↗

Illuminating the charged leptons in the proton

The description of the structure of proton is fundamental in order to describe the standard model processes at the LHC as well as for the searching of New Physics. Quantum fluctuations imply the presence of photons and leptons inside the proton, which admit a parton distribution function (PDF). Although the lepton PDFs are expected to be small, its presence opens new production mechanisms. In order to explore the lepton - induced processes at the LHC, a precise determination of the leptonic content of the proton is needed. In this paper we propose to constrain the content of charged leptons inside the proton through the study of the QED Compton scattering in ultraperipheral proton - nucleus collisions at the LHC. We estimate the total cross sections and associated distributions considering different models for the lepton PDFs and distinct lepton flavours. We demonstrate that a future experimental analysis of this process is feasible and that it can be used to constrain the content of electrons, muons and taus inside the proton.

hep-ph↗

Exclusive doubly charged Higgs boson pair production in $pp$ collisions at the LHC

The type II seesaw model predicts the existence of a doubly charged Higgs boson ($H ^{\pm\pm}$), which can be produced through the Drell - Yan process and photon -- induced interactions at hadronic colliders. In recent years, such reactions have been largely investigated in inclusive processes, where both incident protons breakup and a large number of particles is produced in addition to the doubly charged Higgs pair. In this paper, we investigate, for the first time, the possibility of searching for $H ^{\pm\pm}$ in exclusive processes, which are characterized by two rapidity gaps and two intact very forward protons in final state. We estimate the associated cross section making use of the exclusive nature of the final state, together with the use of timing information provided by forward proton detectors. Moreover, the background is estimated considering distinct amounts of pile-up. Our results indicate that the exclusive doubly charged Higgs pair production is a promising way to search for signatures of the type II seesaw and to obtain lower mass bounds on $H ^{\pm\pm}$.

hep-ph↗

Challenging exclusive top quark pair production at low and high luminosity LHC

The elastic production of top quark pairs in $pp$ collisions at low and high luminosity regimes is investigated in detail. We extend the study performed in Phys. Rev. D102, 074014 (2020) which has demonstrated that the sum of two semi-exclusive $t\bar{t}$ production modes, namely in photon-Pomeron and Pomeron-Pomeron interactions, can be experimentally measured when the $t\bar{t}$ system decays semi-leptonically, $t\bar{t}\rightarrow jjblν_l\bar{b}$, both forward protons are tagged and a low amount of pile-up is present. In this study we focus on separating individual channels and a special attention is paid to the situation at high-luminosity LHC environment. We observe that the separation of the pomeron-pomeron and photon-photon events is a challenging task, especially at high amounts of pile-up even with an optimistic 10~ps resolution of timing detectors. In contrast, the photon-Pomeron signal is relatively well separable from all backgrounds at low levels of pile-up, allowing us to discover the elastic $t\bar{t}$ production and probe, for the first time, the production of a top quark pair in the photon-Pomeron interactions. The diffractive photoproduction of such a complex system as the $t\bar{t}$ pair hence can be used not only to study diffractive properties of the scattering amplitude but also to search for new physics beyond the Standard Model, and consequently to be a solid part of the physics programme of forward proton detectors at LHC.

hep-ph↗

Exclusive dilepton production at forward rapidities in $PbPb$ collisions

The dilepton production in diffractive and exclusive processes at forward rapidities considering ultraperipheral $PbPb$ collisions at the LHC is investigated. Predictions for the $e^+ e^-$, $μ^+ μ^-$ and $τ^+ τ^-$ cross sections are presented taking into account of realistic cuts that can be implemented by the LHCb Collaboration in a future experimental analysis. Our results indicate that the background associated with the diffractive production can be strongly suppressed and the exclusive processes can be cleanly separated. For the $τ^+ τ^-$ production, the semi and purely leptonic decay channels are considered. Our results indicate that a future experimental analysis of the dilepton production at the LHCb is feasible and can be useful to search for BSM physics.

hep-ph↗

Top quark pair production in the exclusive processes at LHC

We analyze the LHC prospects for measurements of the $t\bar{t}$ pair produced exclusively in photon-photon or semi-exclusively in photon-Pomeron and Pomeron-Pomeron processes using protons tagged in forward proton detectors on both sides of the interaction point. These processes are interesting from the point of view of a possible measurement of the top quark mass and constraining models used in Beyond Standard Model physics. Focusing on the semi-leptonic channel, $t\bar{t}\rightarrow jjblν_l\bar{b}$, making use of the exclusive nature of the final state, together with the use of timing information provided by forward proton detectors, relevant exclusive and inclusive backgrounds are studied in detail for different luminosity (or pile-up) scenarios and found to be important for further considerations. While good prospects are found for observing the signal, the top quark mass measurement turns out not to be competitive with measurements in inclusive channels.

hep-ph↗

Exclusive vector meson production in electron-ion collisions at the EIC, LHeC and FCC-$eh$

The exclusive vector meson production in electron-ion collisions for the energies of the future colliders is investigated. We present predictions for the coherent and incoherent $ϕ$ and $J/ψ$ production in $eAu$ collisions considering the possible states of nucleon configurations in the nuclear wave function and taking into account of the non-linear corrections to the QCD dynamics. The cross sections and transverse momentum distributions are estimated assuming the energies of the Electron-Ion Collider (EIC), Large Hadron Electron Collider (LHeC) and Future Circular Collider (FCC-$eh$). Our results indicate that a future experimental analysis of these processes can shed light on the modeling of the gluon saturation effects and constrain the description of the QCD dynamics at high energies.

hep-ph↗

Coherent and incoherent $J/Ψ$ photoproduction in $PbPb$ collisions at the LHC, HE -- LHC and FCC

The coherent and incoherent $J/Ψ$ photoproduction in $PbPb$ collisions are investigated considering the possible states of nucleon configurations in the nuclear wave function and taking into account of the non - linear corrections to the QCD dynamics. The cross sections and the rapidity and transverse momentum distributions are estimated for the energies of the next run of the LHC, High -- Energy LHC and Future Circular Collider. Our results indicate that a future experimental analysis of these processes will be useful to discriminate between different approaches for the QCD dynamics as well to improve our description of the gluon saturation effects.

hep-ph↗

Higgs boson production in photon-photon interactions with proton, light-ion, and heavy-ion beams at current and future colliders

The production of the Higgs boson in photon-photon interactions with proton and nucleus beams at three planned or proposed future CERN colliders --- the high-luminosity Large Hadron Collider (HL-LHC), the high-energy LHC (HE-LHC), and the Future Circular Collider (FCC) --- is studied. The cross sections for the process AA$\xrightarrow{γγ}$(A)H(A), with the ions A surviving the interaction and the Higgs scalar exclusively produced, are computed with MadGraph 5 modified to include the corresponding elastic $γ$ fluxes, for Pb-Pb, Xe-Xe, Kr-Kr, Ar-Ar, O-O, p-Pb, and p-p over the nucleon-nucleon collision energy range $\sqrt{s}\approx 3$--100 TeV. Simulations of the $γγ\to H \to b\bar{b}$ decay mode --- including realistic (mis)tagging and reconstruction efficiencies for the final-state b-jets, as well as appropriate kinematical selection criteria to reduce the similarly computed $γγ\to b\bar{b},c\bar{c},q\bar{q}$ continuum backgrounds --- have been carried out. Taking into account the expected luminosities for all systems, the yields and significances for observing the Higgs boson in ultraperipheral collisions (UPCs) are estimated. At the HL-LHC and HE-LHC, the colliding systems with larger Higgs significance are Ar-Ar(6.3 TeV) and Kr-Kr(12.5 TeV) respectively, but $3σ$ evidence for two-photon Higgs production would require 200 and 30 times larger integrated luminosities than those planned today at both machines. Factors of ten can be gained by running for a year, rather than the typical 1-month heavy-ion LHC operation, but the process will likely remain unobserved until a higher energy hadron collider, such as the FCC, is built. In the latter machine, the $5σ$ observation of Higgs production in UPCs is feasible in just the first nominal run of Pb-Pb and p-Pb collisions at $\sqrt{s} = 39$ and 63 TeV respectively.

hep-ph↗

Prospects for $γγ\to$ Higgs observation in ultraperipheral ion collisions at the Future Circular Collider

We study the two-photon production of the Higgs boson, $\rm γγ\to H$, at the Future Circular Collider (FCC) in ultraperipheral PbPb and pPb collisions at $\sqrt{s_{NN}} = 39$ and 63 TeV. Signal and background events are generated with MADGRAPH 5, including $γ$ fluxes from the proton and lead ions in the equivalent photon approximation, yielding $\rm σ(γγ\to H)$ = 1.75 nb and 1.5 pb in PbPb and pPb collisions respectively. We analyse the H$\,\to b\bar{b}$ decay channel including realistic reconstruction efficiencies for the final-state $b$-jets, showered and hadronized with PYTHIA 8, as well as appropriate selection criteria to reduce the dominant exclusive $γγ\to b\bar{b}$ continuum background. Observation of $\rm PbPb\xrightarrow{γγ}(Pb)\,H\,(Pb)$ is achievable in the first year with the expected PbPb integrated luminosities.

hep-ph↗

Measurements of $γγ\to \mbox{Higgs}$ and $γγ\to W^{+}W^{-}$ in $e^{+}e^{-}$ collisions at the Future Circular Collider

The measurements of the two-photon production of the Higgs boson and of $W^{\pm}$ boson pairs in $e^{+}e^{-}$ collisions at the Future Circular Collider (FCC-ee) are investigated. The processes $e^{+}e^{-}\xrightarrow{γγ}e^+\,{\rm H}\,e^-,e^+\,{\rm W^+W^-}\,e^-$ are computed using the effective photon approximation for electron-positron beams, and studied in their ${\rm H}\to b\bar{b}$ and ${\rm W^+W^-}\to 4j$ decay final-states including parton showering and hadronization, jet reconstruction, $e^\pm$ forward tagging, and realistic experimental cuts. After selection criteria, up to 75 Higgs bosons and 6600 $\rm W^{\pm}$ pairs will be reconstructed on top of controllable continuum backgrounds at $\sqrt{s} = $240 and 350 GeV for the total expected integrated luminosities, by tagging the scattered $e^\pm$ with near-beam detectors. A 5$σ$ observation of $γγ\to$H is thereby warranted, as well as high-statistics studies of triple $\rm γWW$ and quartic $\rm γγWW$ electroweak couplings, improving by at least factors of 2 and 10 the current limits on dimension-6 anomalous quartic gauge couplings.

hep-ph↗