We calculate differential cross sections for exclusive production of heavy charged scalar, weakly interacting particles (charged Higgs bosons, charged technipions, etc.) via photon-photon exchanges in the $p p \to p p H^+ H^-$ reaction with exact $2 \to 4$ kinematics. We present distributions in rapidities, transverse momenta, and correlations in azimuthal angles between the protons and between the charged Higgs bosons. As an example, the integrated cross section for $\sqrt{s}$ = 14~TeV (LHC) is about 0.1~fb and about 0.9~fb at the Future Circular Collider (FCC) for $\sqrt{s}$ = 100~TeV when assuming $m_{H^{\pm}} = 150$~GeV. The results are compared with results obtained within standard equivalent-photon approximation known from the literature. We discuss the role of the Dirac and Pauli electromagnetic form factors of the proton. We have also performed first calculations of cross sections for the exclusive diffractive Khoze-Martin-Ryskin mechanism. We have estimated limits on the $g_{h H^+ H^-}$ coupling constant within two-Higgs dublet model based on recent experimental data from the LHC. The diffractive contribution is, however, much smaller than the $γγ$ one. The $Z γ$, $γZ$, and $ZZ$ exchanges give even smaller contributions. Absorption corrections are calculated for the first time differentially for various distributions. In general, they lead to a damping of the cross section. The damping depends on the $M_{H^{+}H^{-}}$ invariant mass and on $t$ four-momentum transfers squared. In contrast to diffractive processes, the larger the collision energy, the smaller the effect of absorption. We discuss a possibility to measure the exclusive production of two charged Higgs bosons with the help of so-called "forward proton detectors" at the LHC experiments.
The two-photon exclusive production of lepton pairs at the Electron-Ion Collider will open interesting research directions thanks to a very high luminosity and clean experimental conditions. A survey of the scientific potential of such studies is reported. In particular, we consider unique measurements of the proton elastic electromagnetic form-factors and a possibility of studying the anomalous electromagnetic dipole moments of $τ$ leptons.
We consider QCD radiative corrections to Standard Model Higgs boson production in association with a W boson in hadron collisions. We present a fully exclusive calculation up to next-to-next-to-leading order (NNLO) in QCD perturbation theory. To perform this NNLO computation, we use a recently proposed version of the subtraction formalism. Our calculation includes finite-width effects, the leptonic decay of the W boson with its spin correlations, and the decay of the Higgs boson into a bbbar pair. We present selected numerical results at the Tevatron and the LHC.
We investigate the resonant production of color octet muons in order to explore the discovery potential of the FCC-based μp colliders. It is shown that search potential of μp colliders essentially surpass potential of the LHC and would exceed that of FCC pp collider.
Recently proposed Future Circular Collider based muon-proton colliders will allow investigating lepton-hadron interactions at the highest center-of-mass energy. In this study, we investigate the potential of these colliders for a four-fermion contact interactions search. Regarding the constructive and destructive interferences of contact interactions, we estimated discovery, observation, and exclusion limits on the compositeness scale for the left-left, right-right, left-right, and right-left helicity structures. This study's findings show that the FCC-based μp colliders have great potential f…
The remarkable synergy and complementarity between the circular ${\rm e^+ e^-}$ and pp colliders has been extensively discussed. In this short document, we investigate the complementarity between the proposed circular and linear ${\rm e^+ e^-}$ colliders at the electroweak and TeV scale. This complementarity could be exploited on a world-wide scale, if both a large circular and a linear infrastructures were available. A possible implementation of such a complementary program is shown.
The next generation of $e^+e^-$ colliders will offer a possibility of clean testing of QCD dynamics. Recent progress in the theoretical description of exclusive processes permits for many of them a consistent use of the perturbative QCD methods. We find that already on the basis of Born approximation, the exclusive diffractive production of two $ρ$ mesons from virtual photons at very high energies should be measurable at the linear collider (LC).
A few examples of exclusive processes at high energy are discussed. Several mechanisms are presented. The differential distributions are shown. The possibilities to measure the processes are discussed.
The cross section for exclusive $Υ$ ultraperipheral photoproduction at present and future colliders is determined using the low $x$ gluon PDF extracted from an analysis of exclusive $J/ψ$ measurements performed at HERA and the LHC. Predictions are given at next-to-leading order in collinear factorisation over a wide $γp$ centre-of-mass energy range, calculated assuming the non-relativistic approximation for the $Υ$ wave function, and with skewing corrections incorporated.
In this paper we analyze the associated $ϕ$ and $J/Ψ$ photoproduction in ultraperipheral $PbPb$ collisions through the double scattering mechanism for the energies of the Large Hadron Collider (LHC) and Future Circular Collider (FCC). Our results complement a previous analysis for the $ρρ$, $J/ΨJ/Ψ$ and $ρJ/Ψ$ production. We present our predictions for the total cross sections and rapidity distributions considering the rapidity ranges covered by the ALICE and LHCb detectors, which indicate that a future experimental analysis of $ϕJ/Ψ$ final state is feasible. These results point out that the s…
Groundbreaking studies of exclusive physics processes at the Tevatron have demonstrated that proton-(anti)proton colliders are not only quark-antiquark but also gluon-gluon colliders, photon-photon and photon - gluon colliders. These studies are briefly reviewed in this paper.
Calculations of central exclusive diffractive di-pion continuum production are presented in the Regge-eikonal approach. Data from ISR, STAR, CDF and CMS were analyzed and compared with theoretical description. We also consider theoretical predictions for LHC, possible nuances and problems of calculations and prospects of investigations at present and future hadron colliders.
We describe various studies relevant for top physics at future circular collider projects currently under discussion. We show how highly-massive top-antitop systems produced in proton-proton collisions at a center-of-mass energy of 100 TeV could be observed and employed for constraining top dipole moments, investigate the reach of future proton-proton and electron-positron machines to top flavor-changing neutral interactions, and discuss top parton densities.
We critically re-examine the calculation of central production of dijets in quasi-elastic hadronic collisions. We find that the process is not dominated by the perturbative contribution, and discuss several sources of uncertainties in the calculation.
The central exclusive production of $χ_{c}$ and $χ_{b}$ at the LHC, RHIC and Tevatron energies is analyzed, using the recent unintegrated parton distribution (UGDs) functions available in the package TMDlib. Comparison with data is performed, which tests the underlying assumptions basing the theoretical approach and it can constrain the unintegrated gluon distribution function at the small-$x$ region. Predictions for LHC energies using recent UGDs based in CCFM formalism are provided. It is explored the underlying uncertainties on this production as the choice for the unintegrated gluon distri…
In the present work, $k_T$-factorization formalism is applied to compute the exclusive dilepton production by timelike Compton scattering (TCS) in $eA$, $pA$ and $AA$ collisions. The nuclear effects are investigated considering heavy and light ions. The production cross section in terms of invariant mass and rapidity distribution of the lepton pair is shown. The analysis is done for electron-ion collisions at the Large Hadron-Electron Collider (LHeC), its high-energy upgrade (HE-LHeC) and at the Future Circular Collider (FCC) in lepton-hadron mode. Additionally, ultraperipheral heavy ion colli…
We review the subject of central exclusive particle production at high energy hadron colliders. In particular we consider reactions of the type A + B -> A + X + B, where X is a fully specified system of particles that is well separated in rapidity from the outgoing beam particles. We focus on the case where the colliding particles are strongly interacting and mainly they will be protons (or antiprotons) as at the ISR, SppS, Tevatron and LHC. The data are surveyed and placed within the context of theoretical developments.
The theoretical and experimental aspects of particle production from the strong equivalent photon fluxes present at high energy hadron colliders are reviewed. The goal is to show how photons at hadron colliders can improve what we have learnt from experiments with lepton beams. Experiments during the last 5-10 years have shown the feasibility of studying photoproduction in proton-proton and heavy-ion collisions. The experimental and theoretical development has revealed new opportunities as well as challenges.
We review exclusive top pair production including decays at a future high-energy lepton collider, both in the threshold region and for higher energies. For the continuum process, we take complete QCD next-to-leading order matrix elements for the $2\to 6$ process with leptonic W decays into account. At threshold, we match the fixed-order relativistic QCD-NLO cross section to a nonrelativistic cross section with next-to-leading logarithmic (NLL) threshold resummation implemented via a form factor.
Central exclusive Higgs boson production, pp -> p + H + p, at the LHC and s-channel resonant Higgs production in the photon-collider option of the ILC can provide a very important contribution to the comprehensive study of the Higgs sector. Especially attractive is the b bbar Higgs decay mode, which for certain MSSM scenarios may become the discovery channel in exclusive Higgs production at the LHC and the Photon Collider (PC). Strongly suppressed and controllable backgrounds is an obvious requirement for the success of these exclusive measurements. One of the main sources of background comes …
The Future Circular Collider in the $\mathrm{e^{+}e^{-}}$ configuration offers the opportunity to significantly improve SM measurements with dedicated runs at the Z-pole, WW threshold, ZH (240 GeV), and $\mathrm{t}\bar{\mathrm{t}}$ threshold. With a factor of approximately $10^{5}$ more statistics at the Z-pole and $10^{4}$ at the WW threshold than at LEP, the FCC-ee will enable the extraction of the strong coupling $α_{s}$ at the per-mille level. Parton showering studies exploiting the pure gluon sample from $\mathrm{ZH}({\rightarrow} \mathrm{gg})$ will greatly improve our understanding of gl…
The future FCC-ee collider is designed to deliver $\mathrm{e^+e^-}$ collisions to study with ultimate precision the Z, W, and Higgs bosons, and the top quark. In a high-statistics scan around the Z pole, $1.3\times 10^{11}$ events $\mathrm{Z}\toττ$ will be produced, the largest sample of $ττ$ events foreseen at any lepton collider. With their large boost, $τ$ leptons from Z decays are particularly well suited for precision measurements. The focus of this report is on tests of lepton universality from precision measurement of $\boldsymbolτ$ properties and on tests of charged lepton flavour viol…
In this paper we study leading neutron production in photon - hadron interactions which take place in $pp$ and $pA$ collisions at large impact parameters. Using a model that describes the recent leading neutron data at HERA, we consider exclusive vector meson production in association with a leading neutron in $pp/pA$ collisions at RHIC and LHC energies. The total cross sections and rapidity distributions of $ρ$, $ϕ$ and $J/Ψ$ produced together with a leading neutron are computed. Our results indicate that the study of these processes is feasible and that it can be used to improve the understa…
The central exclusive production (CEP) of heavy resonance states that subsequently decay into meson pairs, MMbar, is an important signature for such processes at hadron colliders. However there is a potentially important background from the direct QCD production of meson pairs, as mediated for example by the exclusive gg --> MMbar hard scattering subprocess. This is in fact an interesting process in its own right, testing novel aspects of perturbative QCD technology. We explicitly calculate the gg --> MMbar helicity amplitudes for different meson states within the hard exclusive formalism, and…
Central exclusive production (CEP) processes in high-energy hadron-hadron collisions provide an especially clean environment in which to measure the nature and quantum numbers (in particular, the spin and parity) of new resonance states. Encouraged by the broad agreement between experimental measurements and theoretical predictions based on the Durham approach, we perform a detailed phenomenological analysis of diphoton and meson pair CEP final states, paying particular attention to the theoretical uncertainties in the predictions, including those from parton distribution functions, higher-ord…
In this paper we study the high energy exclusive photoproduction of heavy quarkonia pairs in the leading order of the strong coupling constant $α_{s}$. In the suggested mechanism the quarkonia pairs are produced with opposite charge parities, and have predominantly oppositely directed transverse momenta. Using the Color Glass Condensate approach, we estimated numerically the production cross-sections in the kinematics of the forthcoming electron-proton colliders, as well as proton-ion colliders in ultraperipheral collisions. We found that the cross-sections are within the reach of planned expe…
We present the next-to-leading order QCD corrected rate for the production of a scalar Higgs boson with a pair of high p_T bottom and anti-bottom quarks at the Tevatron and at the Large Hadron Collider. Results are given for both the Standard Model and the Minimal Supersymmetric Standard Model. The exclusive b-bbar-h production rate is small in the Standard Model, but it can be greatly enhanced in the Minimal Supersymmetric Standard Model for large tan(beta), making b-bbar-h an important discovery mode. We find that the next-to-leading order QCD results are much less sensitive to the renormali…
We study the expected sensitivity to measure the branching ratio of Higgs boson decays to invisible particles at a future circular \epem collider (FCC-ee) in the process $e^+e^-\to HZ$ with $Z\to \ell^+\ell^-$ ($\ell=e$ or $μ$) using an integrated luminosity of 3.5 ab$^{-1}$ at a center-of-mass energy $\sqrt{s}=240$ GeV. The impact of the energy spread of the FCC-ee beam and of the resolution in the reconstruction of the leptons is discussed. %Two different detector concepts are considered: a detector corresponding to the CMS reconstruction performances and the expected design of the ILC detec…
Within the framework of the perturbative QCD approach, we calculate the time-like $B_cB_c(B_c^*)$ form factors $F(Q^2)$ and $A_2(Q^2)$. We include relativistic corrections and QCD corrections, either of which can give about $20\%$ correction to the leading-order contribution, but there are cancellation effects between them. We calculate the cross sections of the $e^+e^-\to B_c^-B_c^+(B_c^{*+})$ processes. The cross sections are enhanced at the $Z$ pole to be $σ^{PP}(Q=m_Z) \sim 1.3\times10^{-5}\text{pb}$ and $σ^{PV}(Q=m_Z) \sim 2.5\times10^{-5}\text{pb}$, which are still too small to be detect…
We investigate the potentialities offered by the study of J/psi exclusive photo-production in ultra-peripheral collisions at a fixed-target experiment using the proton and lead LHC beams (generically denoted as AFTER@LHC) on hydrogen targets and at RHIC in the collider mode. We compare the expected counting rates in both set-ups. Studying Single-Transverse-Spin Asymmetries (A_N) in such a process provides a direct path to the proton Generalised Parton Distribution (GPD) E_g(x,xi,t). We evaluate the expected precision on A_N for realistic conditions with the LHCb detector in pH(pol) and PbH(pol…
Central exclusive double diffractive Higgs boson production, p p \to p + H + p, is now recognised as an important search scenario for the LHC. We consider the case when the Higgs boson decays to two W bosons, one of which may be off-mass-shell, that subsequently decay to the q qbar l nu final state. An important background to this is from the QCD process g g \to W q qbar, where the two gluons are required to be in a J_z=0, colour-singlet state. We perform an explicit calculation and investigate the salient properties of this potentially important background process.
In this work the $k_{\perp}$-factorization formalism is applied to compute the exclusive $Z^0$ boson photoproduction in $ep$ and $eA$ collisions. The study is also extended to $pp$ and $AA$ processes. The nuclear effects are investigated considering heavy and light ions. Analytical models for the unintegrated gluon distribution are taken into account and the corresponding theoretical uncertainty is quantified. The analysis is done for electron-ion collisions at the Large Hadron-Electron Collider (LHeC), its high-energy upgrade (HE-LHeC) and at the Future Circular Collider (FCC) in lepton-hadro…
At the high luminosity electron-positron circular colliders like FCC-ee in CERN and CEPC in China it will possible to measure very precisely $e^+e^-\to Zγ$ process with subsequent Z decay into particles invisible in the detector, that is into three neutrina of the Standard Model and possibly into other weakly coupled neutral particles. Apart from the measurement of the total invisible width (which is not the main subject of this work) this process may be used as a source of $Z$ coupling to electron neutrino -- known very poorly. This is possible due to the presence of the $t$-channel $W$ excha…
Circular electron positron colliders, such as the CEPC and FCC-ee, have been proposed to measure Higgs boson properties precisely, test the Standard Model, search for physics beyond the Standard Model, and so on. One of the important goals of these colliders is to measure the $W$ boson mass with great precision by taking data around the $W$-pair production threshold. In this paper, the data-taking scheme is investigated to maximize the achievable precisions of the $W$ boson mass and width with a threshold scan, when various systematic uncertainties are taken into account. The study shows that …
Exclusive vector meson photoproduction associated with a leading baryon ($B = n, Δ^+, Δ^0$) in $pp$ and $pA$ collisions at RHIC and LHC energies is investigated using the color dipole formalism and taking into account nonlinear effects in the QCD dynamics. In particular, we compute the cross sections for $ρ$, $ϕ$ and $J/Ψ$ production together with a $Δ$ and compare the predictions with those obtained for a leading neutron. Our results show that the $V + Δ$ cross section is almost 30 % of the $V + n$ one. Our results also show that a future experimental analysis of these processes is, in princi…
The Future Circular Collider is a new proposed collider at CERN with centre-of-mass energies around 100 TeV in the pp mode. Ongoing studies aim at assessing its physics potential and technical feasibility. Here we focus on updates in physics opportunities accessible in pA and AA collisions not covered in previous Quark Matter contributions, including Quark-Gluon Plasma and gluon saturation studies, novel hard probes of QCD matter, and photon-induced collisions.
In this work we investigate the coherent photoproduction of psi(1S), psi(2S) and Upsilon (1S) states in the proton-nucleus collisions in the LHC energies. Predictions for the rapidity distributions are presented using the color dipole formalism and including saturation effects that are expected to be relevant at high energies. Calculations are done at the energy 5.02 TeV and also for the next LHC run at 8.8 TeV in proton-lead mode. Discussion is performed on the main theoretical uncertainties associated to the calculations.
The threshold scan at future lepton colliders is the most precise known method to determine the top quark mass (well below 100 MeV), a fundamental parameter of the Standard Model that co-determines the stability properties of the electroweak vacuum. We present a new method to match the continuum next-to-leading order QCD corrections with the next-to-leading logarithmic resummation of the Coulomb singularities of the quasi-toponium bound state at threshold where fixed-order perturbation theory is invalid. This matching is performed at the level of the fully exclusive $W^+bW^-\bar{b}$ final stat…
We consider QCD radiative corrections to the production of W and Z bosons in hadron collisions. We present a fully exclusive calculation up to next-to-next-to-leading order (NNLO) in QCD perturbation theory. To perform this NNLO computation, we use a recently proposed version of the subtraction formalism. The calculation includes the gamma-Z interference, finite-width effects, the leptonic decay of the vector bosons and the corresponding spin correlations. Our calculation is implemented in a parton level Monte Carlo program. The program allows the user to apply arbitrary kinematical cuts on th…
Future Circular Collider is one of the next generation energy-frontier proton-proton colliders with 100 TeV center of mass energy and promising very high luminosity. FCC will be an extraordinary machine for searching Beyond the Standard Model physics because of its very high center of mass energy and luminosity. Searching supersymmetric particles via R-parity violated interactions could be listed in promising BSM physics at the FCC. Scalar tau neutrino is one of the most interesting predictions. A search for $\widetildeν_τ$ neutrino decaying into $eμ$ final state via R-parity violated interact…
We compute the cross section for exclusive double-diffractive gamma-gamma production at the Tevatron, $p{\bar p} \to p + γγ+ {\bar p}$, and the LHC. We evaluate both the gluon-gluon and quark-antiquark t-channel exchange contributions to the process. The observation of exclusive gamma-gamma production at the Tevatron will provide a check on the model predictions, and offer an opportunity to confirm the expectations for exclusive double-diffractive Higgs production at the LHC.
One of the interesting portals linking a dark sector and the standard model (SM) is the kinetic mixing between the SM $U(1)_Y$ field with a new dark photon $A'$ from a $U(1)_{A'}$ gauge interaction. Stringent limits have been obtained for the kinetic mixing parameter $ε$ through various processes. In this work, we study the possibility of searching for a dark photon interaction at a circular $e^+e^-$ collider through the process $e^+ e^-\to γA^{\prime *} \to γμ^+μ^-$. We find that the constraint on $ε^2$ for dark photon mass in the few tens of GeV range, assuming that the $μ^+μ^-$ invariant ma…
Exclusive quarkonium pair production in electron-positron collisions is studied in non-relativistic QCD. The obtained cross section for J/ψ+ η_c production in the leading order is confronted against the recent measurements by the Belle Collaboration at KEKB. It is shown that a large renormalization K-factor is necessary to explain the experimental data. We point out that the J^{PC}=0^{-+} nature of the hadronic systems that are assigned to be η_c should be tested by the triple angular distributions in terms of the scattering angle, and, polar and azimuthal angles of J/ψinto leptons. We further…
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 bo…
The N-jettiness event shape divides phase space into N+2 regions, each containing one jet or beam. Using a geometric measure these regions correspond to jets with circular boundaries. We give a factorization theorem for the cross section fully differential in the (transverse) mass of each jet, and compute the corresponding soft function at next-to-leading order (NLO). The ultraviolet divergences are analytically extracted by exploiting hemispheres for interactions between each pair of hard partons, leaving only convergent integrals that are sensitive to the precise boundaries. This method can …
In view of the recent diffractive dijet data from CDF run II, we critically re-evaluate the standard approach to the calculation of central production of dijets in quasi-elastic hadronic collisions. We find that the process is dominated by the non-perturbative region, and that even perturbative ingredients, such as the Sudakov form factor, are not under theoretical control. Comparison with data allows us to fix some of the uncertainties. Although we focus on dijets, our arguments apply to other high-mass central systems, such as the Higgs boson.
The unique Higgs physics opportunities accessible at the CERN Future Circular Collider (FCC) in electron-positron ($\sqrt{s}$ = 125, 240, 350 GeV) and proton-proton ($\sqrt{s}$ = 100 TeV) collisions, are succinctly summarized. Thanks to the large c.m. energies and enormous luminosities (plus clean experimental conditions in the $e^+e^-$ case), many open fundamental aspects of the Higgs sector of the Standard Model (SM) can be experimentally studied: (i) Measurement of the Higgs Yukawa couplings to the lightest fermions: u,d,s quarks (via rare exclusive $H\to(ρ,ω,ϕ)+γ$ decays); and e$^\pm$ (via…
We study the exclusive, double--diffractive production of the Standard Model Higgs particle in hadronic collisions at LHC and FNAL (upgraded) energies. Such a mechanism would provide an exceptionally clean signal for experimental detection in which the usual penalty for triggering on the rare decays of the Higgs could be avoided. In addition, because of the color singlet nature of the hard interaction, factorization is expected to be preserved, allowing the cross--section to be related to similar hard--diffractive events at HERA. Starting from a Fock state expansion in perturbative QCD, we obt…
We study the production of a neutral Higgs boson at a Future Circular Collider in the electron-hadron mode (FCC-eh) through the leading process $e^- p \to ν_e h q $ assuming the decay channel $h \to c \bar{c} $, where $h$ is the Standard Model (SM)-like state discovered at the Large Hadron Collider (LHC). This process is studied in the context of a 2-Higgs Doublet Model Type III (2HDM-III) embedding a four-zero texture in the Yukawa matrices and a general Higgs potential, where both Higgs doublets are coupled with up- and down-type fermions. Flavour Changing Neutral Currents (FCNCs) are well c…
Generalized parton distributions (GPDs) enter QCD factorization theorems for hard exclusive reactions. They encode rich information about hadron partonic structure. We explore a possibility to constrain GPDs in experiments at LHC considering two different exclusive processes: the timelike Compton scattering and the photoproduction of heavy vector mesons.
In this paper we present a detailed analysis of the contribution of the Light -- by -- Light (LbL), Durham and double diffractive processes for the diphoton production in ultraperipheral $PbPb$ collisions at the Large Hadron Collider (LHC), High -- Energy LHC (HE -- LHC) and Future Circular Collider (FCC). The acceptance of the central and forward LHC detectors is taken into account and predictions for the invariant mass, rapidity, transverse momentum and acoplanarity distributions are presented. Our results indicate that the contribution of the Durham and double diffractive processes can be s…
By solving the rate equation in an expanding quark-gluon plasma, we study thermal production of charm quarks in central Pb+Pb collisions at the Future Circular Collider. With the charm quark production cross section taken from the perturbative QCD at the next-to-leading order, we find that charm quark production from the quark-gluon plasma can be appreciable compared to that due to initial hard scattering between colliding nucleons.
