arXiv subjects

Piotr Lebiedowicz

Publications and source records attributed to Piotr Lebiedowicz.

At least 19 recordsLinked to original sources

arXiv2026

Addendum: Production of $\pi^{+} \pi^{-}$ pairs in diffractive photon-proton and in proton-proton collisions revisited, in particular concerning the Drell-S\"oding contribution

We update our analyses concerning the non-resonant (Drell-S\"oding) contribution to the reaction $\gamma^{(*)} p \to \pi^{+} \pi^{-} p$, now including general vertex functions for the coupling of pomeron, $f_{2 \mathbb{R}}$, and $\rho_{\mathbb{R}}$, to pions. This takes into account the off-shellness of the pions. We present a comparison of our tensor-pomeron model, including our new Drell-S\"oding and $\rho$, $\omega$ vector-meson contributions, with data for the $\gamma p \to \pi^{+} \pi^{-} p$ reaction measured by the ZEUS and H1 Collaborations. We find very good agreement of our theory with the experimental data for the $\pi^{+} \pi^{-}$ invariant mass ($M_{\pi \pi}$) and for angular distributions. Here we restrict our analysis to the region $M_{\pi \pi} \lesssim 1.2$ GeV. For higher values of $M_{\pi \pi}$ we will have to consider production of higher-mass mesons. The purpose of the present article is to show that our tensor-pomeron model gives a very good fit to the so-called skewing of the $\rho$-resonance contribution in photoproduction. In fact, it is an old problem/puzzle to understood the difference of the shapes of the $M_{\pi \pi}$ distributions in the region of the $\rho(770)$ resonance in $e^{+} e^{-}$ annihilation and photoproduction. We think that with our results we have obtained for this problem a solution which is very satisfactory from the Quantum-Field-Theory point of view. Our results are also relevant for central-exclusive $\pi^{+} \pi^{-}$ production in ultraperipheral $pp$, A$p$, and AA collisions at the LHC and for photo- and electroproduction of $\pi^{+} \pi^{-}$ at future electron-proton/ion colliders, EIC and LeHC.

hep-ph↗

arXiv2026

Exclusive $D \bar{D}$ pair production with low invariant mass in ultraperipheral Pb-Pb collisions at the LHC

We present predictions for the ultraperipheral heavy-ion reaction ${\rm Pb} {\rm Pb} \to {\rm Pb} {\rm Pb} D \bar{D}$, where $D$ refers to either $D^0$ or $D^+$, limiting to low invariant mass of $D \bar{D}$ and at energies available at the LHC. The calculation of the $\gamma \gamma \to D \bar{D}$ subprocess is done including the continuum mechanisms and the $\chi_{c0}(3860)$ and $\chi_{c2}(3930)$ resonant contributions. These states are considered as candidates for the first excited $P$-wave charmonia $\chi_{c0}(2P)$ and $\chi_{c2}(2P)$. We compare our results for the $\gamma \gamma \to D \bar{D}$ process with the $D \bar{D}$ invariant mass and angular distributions measured by the Belle and BaBar experiments in $e^{+}e^{-}$ collisions. Then, we present first calculations for ultraperipheral Pb-Pb collisions (UPCs) within the equivalent photon approximation in the impact-parameter space. Both, the total cross section and several differential distributions for experimental cuts corresponding to the ALICE, ATLAS, CMS, and LHCb experiments are presented. For instance, the nuclear cross sections for the $D^{0} \bar{D}^{0}$ and $D^{+} D^{-}$ channel at $\sqrt{s_{NN}} = 5.02$ TeV are found to be approximately 100--132 $\mu$b and 29 $\mu$b, respectively, taking into account the cuts on pseudorapidities and transverse momenta of the final state charmed mesons ($|\eta_{D}| < 2.5$, $p_{t,D} > 0.2$ GeV) and for $M_{D \bar{D}} < 4.3$ GeV. Results for $\sqrt{s_{NN}} = 5.36$ TeV are also presented. Cross section for the ${\rm Pb} {\rm Pb} \to {\rm Pb} {\rm Pb} (\gamma \gamma \to \chi_{c0,2}(2P) \to D \bar{D})$ processes is sufficiently large for experimental studies. The back-to-back correlation between charm mesons can be used to separate the exclusive process under consideration from other background processes, and could provide valuable insight into the properties of the excited quarkonia.

hep-ph↗

arXiv2026

Central exclusive production of $\eta$ and $\eta'$ mesons in diffractive proton-proton collisions at the LHC and the nature of the pomeron

Central exclusive production (CEP) of $\eta$ and $\eta'$ mesons in proton-proton collisions at high-energies is discussed. At the LHC the main mechanism for the production of these mesons should be double-pomeron ($\rm I\!P$-$\rm I\!P$) exchange, that is, the fusion reactions ${\rm I\!P I\!P} \to \eta, \eta'$. We show that for a scalar pomeron these fusion reactions are not possible. In contrast, in the tensor-pomeron model CEP of $\eta$ and $\eta'$ mesons via double-pomeron exchange is allowed. We discuss these reactions for the c.m. energy $\sqrt{s} = 29.1$ GeV realised at the WA102 experiment and for $\sqrt{s} = 13$ TeV corresponding to the LHC experiments. Cross sections and distributions are presented and discussed.

hep-ph↗

arXiv2025

Competition of $\chi_{c}(2P)$ quarkonia and continuum in $e^+ e^- \to e^+ e^- D \bar{D}$

We discuss the production of $D \bar{D}$ pairs in $e^+ e^-$ collisions, where $D$ refers to either $D^0$ or $D^+$. The continuum mechanism with the $t/u$-channel vector-meson $D^*$ exchanges are considered. The results of the calculation depend on the parameter of the off-shell form-factor for the virtual $D^*$ mesons. The $D^* D \gamma$ coupling constants are found from the $D^* \to D \gamma$ decays. We find relatively large contribution for the $D^0 {\bar D}^0$ channel and much smaller contribution in the $D^+ D^-$ channel. In the second case we consider also the $D^{\pm}$ exchanges. We conclude that the bump at $M_{D^0 {\bar D}^0} = 3.8$ GeV observed by the Belle and BaBar Collaborations has rather continuum origin than it corresponds to the broad resonance $\chi_{c0}(3860)$. We discuss also production of the $\chi_{c2}(3930)$ resonance which is a candidate for the $\chi_{c2}(2P)$ state. This state can decay into both $D \bar{D}$ channels, however the branching fractions are not well known at present. From a comparison of our model results to the BaBar data we find $B(\chi_{c2}(3930) \to D \bar{D}) = 0.58 \pm 0.13$ using the two-photon width $\Gamma_{\gamma \gamma} = 0.544$ keV (obtained for the Buchm\"uller-Tye potential) evaluated within the light-front approach (NRQCD limit). Our finding of $\Gamma_{\gamma \gamma} \times B(\chi_{c2}(3930) \to D \bar{D}) = 0.32 \pm 0.07$ keV is close to the Belle and BaBar results. Realistic predictions of the differential distributions in several variables and integrated cross-sections are given for the Belle II kinematics.

hep-ph↗

arXiv2025

Production of $\pi^{+}\pi^{-}$ pairs in diffractive photon-proton and in proton-proton collisions revisited, in particular concerning the Drell-S\"oding contribution

We discuss the exclusive photoproduction of $\pi^{+}\pi^{-}$ pairs in photon-proton and in proton-proton collisions at high energies. The $\rho^{0}$, $\omega$, $f_{2}(1270)$, and non-resonant (Drell-S\"oding) contributions are considered. The calculation is based on the tensor-pomeron model. In the Drell-S\"oding contribution we have different subenergies for the $\pi^{+}p$ and $\pi^{-}p$ systems. In the method which we propose now we take this into account. Respecting the gauge-invariance constraints is then a nontrivial problem for which, however, we present a solution here. In the present paper we give in this way a substantial improvement of the calculations for real photoproduction of $\pi^{+}\pi^{-}$ from JHEP 01, 151 (2015), and we extend the calculations to low $Q^{2}$ electroproduction, $0 \leqslant Q^{2} \leqslant 0.5$ GeV$^{2}$. The photo- and electroproduction amplitudes are then the basis for the calculation of central exclusive production (CEP) of $\pi^{+}\pi^{-}$ pairs in $pp$ collisions, where at least one proton participates in the CEP via a virtual-photon emission. The revised model leads to enhanced cross sections and gives an increased skewing of the $\rho^{0}$ spectral shape. For the $pp \to pp \pi^{+}\pi^{-}$ reaction, we calculate differential cross sections as function of the two-pion invariant mass, pion transverse momentum and pion pseudorapidity. This research is relevant in the context of ALICE, ATLAS, CMS, and LHCb measurements in $pp$ collisions. Our results can also serve as basis for the description of coherent $\pi^{+}\pi^{-}$ production in ultra-peripheral $p$A and AA collisions at the LHC. The formulas given in our paper can be used for the analysis of photoproduction and small-$Q^{2}$ electroproduction in $ep$ collisions at high energies. Such data exist from the HERA experiments and will be obtained in the future at the electron-ion colliders.

hep-ph↗

arXiv2025

Central exclusive production of $\eta$ and $\eta'$ mesons in diffractive proton-proton collisions at the LHC within the tensor-pomeron approach

We present a study of the central exclusive production (CEP) of $\eta$ and $\eta'(958)$ mesons in diffractive proton-proton collisions at high energies. The amplitudes, including pomeron and $f_{2 \mathbb{R}}$ reggeon exchanges, are calculated within the tensor-pomeron model. Absorption effects are also taken into account at the amplitude level. We fit some undetermined model parameters (coupling constants and cutoff parameters in form factors) to the WA102 experimental data and then make predictions for the LHC energy $\sqrt{s} = 13$ TeV. Both, total cross sections and several differential distributions are presented. For $pp \to pp \eta$, we find an upper limit for the total cross section of 2.5 $\mu$b for pseudorapidity of the $\eta$ meson $|\eta_{M}| < 1$ and 5.6 $\mu$b for $2 < \eta_{M} < 5$. For $pp \to pp \eta'$, we predict the cross section to be in the range of 0.3-0.7 $\mu$b for pseudorapidity of the $\eta'$ meson $|\eta_{M}| < 1$ and 0.9-2.1 $\mu$b for $2 < \eta_{M} < 5$. This opens the possibility to study diffractive production of pseudoscalar mesons in experiments at the LHC. We discuss if there are arguments from SU(3)-flavor symmetry which would forbid pomeron-pomeron fusion giving an $\eta$ meson. In our opinion such arguments do not exist. We also consider CEP of the pseudoscalars $\eta$ and $\eta'(958)$ and the pseudovector meson $f_{1}(1285)$ in diffractive proton-proton collisions in a theory with a scalar pomeron. We show that none of these particles can be produced in this way in the scalar-pomeron theory. Thus, experimental observation of any of these particles in the above CEP processes at the LHC would give striking evidence against a scalar character of the pomeron.

hep-ph↗

arXiv2025

Exclusive $\eta$ production in proton-proton collisions at energies available at the GSI Facility for Antiproton and Ion Research

The cross sections for the $p p \to p p \eta$ reaction are evaluated at energies relevant for the HADES, PANDA, and SIS100 experiments at GSI-FAIR. Consideration includes the $\eta$-bremsstrahlung mechanism involving intermediate proton exchange via the $\pi^{0}$, $\eta$, $\rho^{0}$, and $\omega$ exchanges and the mechanism involving the nucleon resonances $N(1535)$, $N(1650)$, $N(1710)$, and $N(1880)$ excited via the pseudoscalar- and/or vector-meson exchanges, depending on the model. The role of the $\omega \omega$- and $\rho^{0} \rho^{0}$-fusion processes with the reggeized vector-meson exchanges is also discussed. The calculation is done in an effective Lagrangian approach. To determine the parameters of the model, the $\gamma p \to \eta p$ and $\pi^{-} p \to \eta n$ reactions are studied and the results are then compared with the Crystal Ball and CLAS data. For the $p p \to p p \eta$ reaction, the model results are compared with the energy dependence of the cross section measured far from the threshold and with the differential distributions $d\sigma/d\cos{\theta_{\eta}}$ and $d\sigma/dp_{\eta}$ measured by the DISTO Collaboration. The comparison shows that the $N(1535)$ resonance is the dominant contribution and that other contributions are also important due to interference effects. Assuming that the $\rho$ exchange is the dominant resonant excitation process, the model is able to describe the available data, e.g., it reproduces the shape of the angular distributions measured by the DISTO Collaboration. Predictions are given for the HADES experiment at center-of-mass energy of $\sqrt{s} = 3.46$ GeV, which can be verified in the near future, and for planned PANDA and SIS100 experiments at higher energies.

hep-ph↗

arXiv2024

Different versions of soft-photon theorems exemplified at leading and next-to-leading terms for pion-pion and pion-proton scattering

We investigate the photon emission in pion-pion and pion-proton scattering in the soft-photon limit where the photon energy $ω\to 0$. The expansions of the $π^{-} π^{0} \to π^{-} π^{0} γ$ and the $π^{\pm} p \to π^{\pm} p γ$ amplitudes, satisfying the energy-momentum relations, to the orders $ω^{-1}$ and $ω^{0}$ are derived. We show that these terms can be expressed completely in terms of the on-shell amplitudes for $π^{-} π^{0} \to π^{-} π^{0}$ and $π^{\pm} p \to π^{\pm} p$, respectively, and their partial derivatives with respect to $s$ and $t$. The~structure term which is non singular for $ω\to 0$ is determined to the order $ω^{0}$ from the gauge-invariance constraint using the generalized Ward identities for pions and the proton. For the reaction $π^{-} π^{0} \to π^{-} π^{0} γ$ we discuss in detail the soft-photon theorems in the versions of both F.E. Low and S. Weinberg. We show that these two versions are different and must not be confounded. Weinberg's version gives the pole term of a Laurent expansion in $ω$ of the amplitude for $π^{-} π^{0} \to π^{-} π^{0} γ$ around the phase-space point of zero radiation. Low's version gives an approximate expression for the above amplitude at a fixed phase-space point, corresponding to non-zero radiation. Clearly, the leading and next-to-leading terms in theses two approaches must be, and are indeed, different. We show their relation. We also discuss the expansions of differential cross sections for $π^{-} π^{0} \to π^{-} π^{0} γ$ with respect to $ω$ for $ω\to 0$.

hep-ph↗

arXiv2024

Exclusive Bremsstrahlung of One and Two Photons in Proton-Proton Collisions

We discuss the diffractive bremsstrahlung of a single photon in the $pp \to pp γ$ reaction at LHC energies and at forward photon rapidities. We compare the results for our standard approach, based on QFT and the tensor-Pomeron model, with two versions of soft-photon approximations, SPA1 and SPA2, where the radiative amplitudes contain only the leading terms proportional to $ω^{-1}$ (the inverse of the photon energy). SPA1, which does not have the correct energy-momentum relations, performs surprisingly well in the kinematic range considered, namely at very forward photon rapidities and $0.02 < ξ_{1,2} < 0.1$, the relative energy loss of the protons, corresponding to small values of the photon transverse momentum. Azimuthal correlations between outgoing particles are presented. We discuss also the role of the $p p \to p p π^0$ background for single photon production. We discuss also the possibility of a measurement of the $pp \to pp γγ$ reaction. Our predictions can be verified by ATLAS-LHCf combined experiments.

hep-ph↗

arXiv2023

Soft-photon theorem for pion-proton elastic scattering revisited

We discuss the reactions $\pi p \to \pi p$ and $\pi p \to \pi p \gamma$ from a general quantum field theory (QFT) point of view, describing these reactions in QCD and lowest relevant order of electromagnetism. We consider the pion-proton elastic scattering both off shell and on shell. The on-shell amplitudes for $\pi^{\pm} p \to \pi^{\pm} p$ scattering are described by two invariant amplitudes, while the off-shell amplitudes contain eight invariant amplitudes. We study the photon emission amplitudes in the soft-photon limit where the c.m. photon energy $\omega \to 0$. The Laurent expansion in $\omega$ of the $\pi^{\pm} p \to \pi^{\pm} p \gamma$ amplitudes is considered and the terms of the orders $\omega^{-1}$ and $\omega^{0}$ are derived. These terms can be expressed by the on-shell invariant amplitudes and their partial derivatives with respect to $s$ and $t$. The pole term $\propto \omega^{-1}$ in the amplitudes corresponds to Weinberg's soft-photon theorem and is well known from the literature. We derive the next-to-leading term $\propto \omega^{0}$ using only rigorous methods of QFT. We give the relation of the Laurent series for $\pi^{0} p \to \pi^{0} p \gamma$ and Low's soft-photon theorem. Our formulas for the amplitudes in the limit $\omega \to 0$ are valid for photon momentum $k$ satisfying $k^{2} \geqslant 0$, $k^{0} = \omega \geqslant 0$, that is, for both real and virtual photons. Here we consider a limit where with $\omega \to 0$ we have also $k^{2} \to 0$. We discuss the behavior of the corresponding cross-sections for $\pi^{-} p \to \pi^{-} p \gamma$ with respect to $\omega$ for $\omega \to 0$. We consider cross sections for unpolarized as well as polarized protons in the initial and final states.

hep-ph↗

arXiv2023

Exclusive diffractive bremsstrahlung of one and two photons at forward rapidities: Possibilities for experimental studies in $pp$ collisions at the LHC

We evaluate the cross section for diffractive bremsstrahlung of a single photon in the $pp \to pp γ$ reaction at high energies and at forward photon rapidities. Several differential distributions, for instance, in $y$, $k_{\perp}$ and $ω$, the rapidity, the absolute value of the transverse momentum, and the energy of the photon, respectively, are presented. We compare the results for our standard approach, based on QFT and the tensor-pomeron model, with two versions of soft-photon-approximations, SPA1 and SPA2, where the radiative amplitudes contain only the leading terms proportional to $ω^{-1}$. The SPA1, which does not have the correct energy-momentum relations, performs surprisingly well in the kinematic range considered. We discuss also azimuthal correlations between outgoing particles. The azimuthal distributions are not isotropic and are different for our standard model and SPAs. We discuss also the possibility of a measurement of two-photon-bremsstrahlung in the $pp \to pp γγ$ reaction. In our calculations we impose a cut on the relative energy loss ($0.02 < ξ_{i} < 0.1$, $i = 1,2$) of the protons where measurements by the ATLAS Forward Proton (AFP) detectors are possible. The AFP requirement for both diffractively scattered protons and one forward photon (measured at LHCf) reduces the cross section for $p p \to p p γ$ almost to zero. On the other hand, much less cross-section reduction occurs for $pp \to pp γγ$ when photons are emitted in opposite sides of the ATLAS interaction point and can be measured by two different arms of LHCf. For the SPA1 ansatz we find $σ(pp \to pp γγ) \simeq 0.03$ nb at $\sqrt{s} = 13$ TeV and with the cuts $0.02 < ξ_{i} < 0.1$, $8.5 < y_{3} < 9$, $-9 < y_{4} < -8.5$. Our predictions can be verified by ATLAS and LHCf combined experiments.

hep-ph↗

arXiv2023

Central exclusive diffractive production of a single photon in high-energy proton-proton collisions within the tensor-Pomeron approach

We discuss central-exclusive production (CEP) of photons via different fusion processes in the reaction $pp \to pp γ$ at high energies, available at RHIC and LHC, within the tensor-pomeron model. We consider two types of processes, the photoproduction contribution via the photon-pomeron and photon-reggeon fusion reactions, and the purely diffractive contribution via the reggeon-pomeron and odderon-pomeron fusion reactions. We present predictions for the measurements of photons at midrapidity, $|{\rm y}| < 2.5$, and at relatively low transverse momentum, $0.1~{\rm GeV} < k_{\perp} < 1~{\rm GeV}$. To check the main results of our study the measurement of the outgoing protons is not necessary. This is of relevance, e.g., for the present version of the ALICE detector at the LHC. Several differential distributions, for instance, in ${\rm y}$, $k_{\perp}$ and $ω$, the rapidity, the absolute value of the transverse momentum, and the energy of the photon, respectively, are presented. We show that the photoproduction is an important process in the kinematic region specified above. There it gives a much larger cross section than diffractive bremsstrahlung. This is remarkable as the CEP cross section is of order $α_{\rm em}^{3}$ whereas the bremsstrahlung one is only of order $α_{\rm em}$. On the other hand, the soft-photon bremsstrahlung where the basic $pp \to pp$ reaction is due to strong interaction diffraction is more important than CEP in the forward rapidity range, $|{\rm y}| > 4$, and/or at very low $k_{\perp}$. We leave it as a challenge for the planned ALICE 3 experiment at the LHC to study these two contributions to soft photon production in $pp$ collisions. This could shed new light on the so called ``soft photon puzzle'' in hadron-hadron collisions.

hep-ph↗

arXiv2023

The Tensor Pomeron and Low-x Deeply Virtual Compton Scattering

The two-tensor-pomeron model is applied to deeply virtual Compton scattering (DVCS) on a proton. A good description of the DVCS HERA data at small Bjorken-$x$ is achieved due to a sizeable interference of soft and hard pomeron contributions. We present two fits which differ somewhat in the strength of the hard pomeron contribution. We describe, in the same framework, both the low $Q^{2}$ and high $Q^{2}$ regimes and the transition between them. We find that the soft-pomeron contribution is considerable up to $Q^{2} \sim 20$ GeV$^{2}$. The reggeon exchange term is particularly relevant for describing the scattering of a real photon on a proton measured at lower $γp$ energies at FNAL. We find that the ratio of $γ^{*} p \to γp$ cross-sections for longitudinally and transversely polarized virtual photons strongly increases with $t$. Our findings may be checked in future lepton-nucleon scattering experiments in the low-$x$ regime, for instance, at a future Electron-Ion Collider (EIC) at the BNL and LHeC at the LHC.

hep-ph↗

arXiv2022

Deeply virtual Compton scattering in the tensor-pomeron approach

The two-tensor-pomeron model proposed previously to describe low $x$ DIS data is applied to real and virtual Compton scattering on a proton. The model includes two tensor pomerons, a soft and a hard one, and tensor reggeons. We include contributions of both transverse and longitudinal virtual photons. We show that this model gives a very good description of experimental data at small Bjorken $x$ on deeply virtual Compton scattering (DVCS) from HERA. The reggeon exchange term is particularly relevant for describing the real-photon-proton scattering measured at lower $γp$ energies at FNAL. We present two fits which differ somewhat in the strength of the hard pomeron contribution. In both fits we find that the interference between soft- and hard-pomeron exchange plays an important role. We find that in DVCS the soft-pomeron contribution is considerable up to $Q^{2} \sim 20$ GeV$^{2}$. Our model allows to study the transition from the small-$Q^{2}$ regime, including the photoproduction ($Q^{2} = 0$) limit, to the large-$Q^{2}$ regime, the DIS limit. We also discuss the ratio of cross sections for longitudinally and transversely polarized virtual photons in $γ^{*} p \to γp$ as a function of $|t|$ and $Q^2$. The ratio $\tilde{R}(Q^{2},W^{2},t) = (dσ_{\rm L} / dt) / (dσ_{\rm T} / dt)$ strongly increases with $t$. Our findings may be checked in future lepton-nucleon scattering experiments in the low-$x$ regime, for instance, at a future Electron-Ion Collider at the BNL (EIC), and, if LHeC is realized, at the LHC.

hep-ph↗

arXiv2022

Soft-photon radiation in high-energy proton-proton collisions within the tensor-Pomeron approach: Bremsstrahlung

We discuss diffractive processes in proton-proton collisions at small momentum transfers without and with photon radiation. We consider the soft exclusive reactions $pp \to pp$, $p\bar{p} \to p\bar{p}$, and $pp \to pp γ$ within the tensor-pomeron and vector-odderon approach. We compare our results with the data for $pp$ and $p\bar{p}$ total cross sections, for the ratio of real to imaginary part of the forward scattering amplitude, and for the elastic $pp$ cross sections, especially those from TOTEM. To describe the low-energy data more accurately the secondary reggeons must be included. We write down the amplitudes for the photon bremsstrahlung in high-energy proton-proton collisions using the tensor-pomeron model. These results are relevant for the c.m. energies presently available at the Relativistic Heavy Ion Collider and at the LHC. We present predictions for the proposed measurements of soft photons with the planned future upgrade of the ALICE experiment at the LHC. We investigate the limits of applicability of the soft-photon approximation (SPA) based on Low's theorem. The corresponding SPA results are compared to those obtained from our complete model. The regions of phase space are given quantitatively where SPA and our complete tensor-pomeron results are close to each other. As an example, let $k_{\perp}$, $\rm y$, and $ω$, be the absolute value of the transverse momentum, the rapidity, and the energy of the photon, respectively, in the overall c.m. system. For the region $1 \; {\rm MeV} < k_{\perp} < 100 \; {\rm MeV}$ and $3.5 < |\rm y| < 5.0$, we find that the SPA Ansatz with only the pole terms $\propto ω^{-1}$ agrees at the percent level with our complete model result up to $ω\cong 2$ GeV.

hep-ph↗

arXiv2021

Central exclusive production of axial-vector $f_{1}$ mesons in proton-proton collisions within the tensor-pomeron approach

We discuss the central exclusive production of $f_{1}$ mesons in proton-proton collisions. The diffractive pomeron-pomeron fusion process within the tensor-pomeron approach is considered. Two ways to construct the pomeron-pomeron-$f_{1}$ coupling are discussed. The theoretical calculation of coupling constants is a challenging problem of nonperturbative QCD. We adjust the parameters of the model to the WA102 experimental data. The total cross section and differential distributions are presented. Predictions for LHC experiments are given. Detailed analysis of the distributions in $ϕ_{pp}$ the azimuthal angle between the transverse momenta of the outgoing protons can help to check different models and to study real pattern of the absorption effects.

hep-ph↗

arXiv2021

Exclusive $pp \to pp K^{0} \bar{K}^{0}$ reaction: $f_{2}(1950)$ resonance versus diffractive continuum

The exclusive reaction $pp \to pp (K^{*0} \bar{K}^{*0} \to K^{+}π^{-}K^{-}π^{+})$ for the LHC experiments is discussed. The amplitudes for the reaction are formulated within the tensor-pomeron approach. We consider two diffractive mechanisms: the $f_{2}(1950)$ $s$-channel exchange mechanism and the $K^{*0}$-exchange mechanism. First mechanism is a candidate for central diffractive production of tensor glueball and the second one is an irreducible continuum. Comparison with data from WA102 experiment are made and predictions for LHC experiments are given. We find that including the continuum contribution alone one can describe the WA102 data reasonably well. A similar behaviour of the continuum and resonance contributions makes an identification of a broad tensor-glueball state in this reaction rather difficult.

hep-ph↗

arXiv2021

Central exclusive diffractive production of axial-vector $f_{1}$ mesons in proton-proton collisions

Exclusive production of axial-vector $f_{1}(1285)$ meson in proton-proton collisions via pomeron-pomeron fusion within the tensor-pomeron approach is discussed. Two ways to construct the pomeron-pomeron-$f_{1}$ coupling are presented. We adjust the parameters of our model to the WA102 experimental data and compare with predictions of the Sakai-Sugimoto model. Predictions for LHC experiments are given.

hep-ph↗