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Piotr Lebiedowicz

Publications and source records attributed to Piotr Lebiedowicz.

At least 37 records · Page 2Linked to original sources
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.

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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.

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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.

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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.

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arXiv2021

Exclusive $f_{1}(1285)$ meson production for energy ranges available at the GSI-FAIR with HADES and PANDA

We evaluate the cross section for the $p p \to p p f_{1}(1285)$ and $p \bar{p} \to p \bar{p} f_{1}(1285)$ reactions at near threshold energies relevant for the HADES and PANDA experiments at GSI-FAIR. We assume that at energies close to the threshold the $ωω\to f_{1}(1285)$ and $ρ^{0} ρ^{0} \to f_{1}(1285)$ fusion processes are the dominant production mechanisms. The vertex for the $VV \to f_{1}$ coupling is derived from an effective coupling Lagrangian. The $g_{ρρf_1}$ coupling constant is extracted from the decay rate of $f_{1}(1285) \to ρ^{0} γ$ using the vector-meson-dominance ansatz. We assume $g_{ωωf_1} = g_{ρρf_1}$, equality of these two coupling constants, based on arguments from the naive quark model and vector-meson dominance. The amplitude for the $VV \to f_{1}$ fusion, supplemented by phenomenological vertex form factors for the process, is given. The differential cross sections at energies close to the threshold are calculated. In order to determine the parameters of the model the $γp \to f_{1}(1285) p$ reaction is discussed in addition and results are compared with the CLAS data. The possibility of a measurement by HADES@GSI is presented and discussed. We performed a Monte Carlo feasibility simulations of the $p p \to p p f_1$ reaction for $\sqrt{s}$ = 3.46 GeV in the $π^+ π^- π^+ π^-$ (not shown explicitly) and $π^+ π^- π^+ π^- π^0$ final states using the PLUTO generator. The latter one is especially promising as a peak in the $π^+ π^- η$ should be observable by HADES.

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arXiv2021

Study of the exclusive reaction $pp \to pp K^{*0} \bar{K}^{*0}$: $f_{2}(1950)$ resonance versus diffractive continuum

We present first predictions of the cross sections and differential distributions for the exclusive reaction $pp \to pp K^{*0} \bar{K}^{*0}$ contributing to the $K^{+} K^{-} π^{+} π^{-}$ channel. The amplitudes for the reaction are formulated within the nonperturbative tensor-pomeron approach. We consider separately the $f_{2}(1950)$ $s$-channel exchange mechanism and the $K^{*0}$ $t/u$-channel exchange mechanism, focusing on their specificities. First mechanism is a candidate for the central diffractive production of tensor glueball and the second one is an irreducible continuum. We adjust parameters of our model, assuming the dominance of pomeron-pomeron fusion, to the WA102 experimental data. We find that including the continuum contribution alone one can describe the WA102 data reasonably well. We present predictions for the reaction $pp \to pp (K^{*0} \bar{K}^{*0} \to K^{+} K^{-} π^{+} π^{-})$ for the ALICE, ATLAS, CMS and LHCb experiments including typical kinematical cuts. We find from our model a cross sections of $σ\cong 17-250$ nb for the LHC experiments, depending on the assumed cuts. Absorption effects are included in our analysis.

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arXiv2020

Inclusive production of $f_2(1270)$ tensor mesons at the LHC via gluon-gluon fusion in the $k_t$-factorization approach

The cross section for inclusive production of $f_2(1270)$ meson is calculated. We include both the mechanism of gluon-gluon fusion as well as the $ππ$ final-state rescattering. The contribution of the gluon-gluon fusion is calculated within the $k_t$-factorization approach with modern unintegrated gluon distribution functions (UGDFs). Some parameters for the $g^* g^* \to f_2$ vertex are extracted from the $γγ\to f_2(1270) \to ππ$ reactions. The results strongly depend on the parametrization of the $g^* g^* \to f_2(1270)$ form factor. Results of our model are compared to the ALICE preliminary data. The gluon-gluon fusion does not explain low-$p_t$ data but could be the dominant mechanism at somewhat larger meson transverse momenta. By adjusting some parameters the pion-pion rescattering can explain the low-$p_t$ region.

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arXiv2020

Searching for odderon exchange in exclusive $pp \to pp ϕ$ and $pp \to pp ϕϕ$ reactions at the LHC

The possibility to use the exclusive $pp \to pp ϕ$ and $pp \to pp ϕϕ$ reactions in identifying the odderon exchange is discussed. So far there is no unambiguous experimental evidence for the odderon, the charge conjugation $C = -1$ counterpart of the $C = +1$ pomeron. Recently proposed tensor-pomeron and vector-odderon model for soft high-energy reactions is applied. For the $p p \to p p ϕ$ reaction at high energies the photon-pomeron fusion is the dominant process and the odderon-pomeron fusion is an interesting alternative. Adding odderon exchange improves considerably description of the proton-proton angular correlations measured by the WA102 collaboration. The $p p \to p p ϕϕ$ process via pomeron-pomeron fusion is advantageous one as here the odderon does not couple to protons. The observation of large $M_{ϕϕ}$ and the rapidity difference $Y_{ϕϕ}$ seems well suited to identify odderon exchange. Comparisons with data from the WA102 experiment are made and predictions for LHC experiments are given.

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arXiv2020

Central exclusive diffractive production of axial-vector $f_{1}(1285)$ and $f_{1}(1420)$ mesons in proton-proton collisions

We present a study of the central exclusive diffractive production of the $f_{1}(1285)$ and $f_{1}(1420)$ resonances in proton-proton collisions. The theoretical results are calculated within the tensor-pomeron approach. Two pomeron-pomeron-$f_{1}$ tensorial couplings labeled by $(l,S) = (2,2)$ and $(4,4)$ are derived. We adjust the model parameters (coupling constants, cutoff constant) to the WA102 experimental data taking into account absorption effects. Both the $(l,S) = (2,2)$ and $(4,4)$ couplings separately allow one to describe the WA102 differential distributions. We compare these predictions with those of the Sakai-Sugimoto model, where the pomeron-pomeron-$f_{1}$ couplings are determined by the mixed axial-gravitational anomaly of QCD. We derive an approximate relation between the pomeron-pomeron-$f_{1}$ coupling constants of this approach and the $(l,S) = (2,2)$ and $(4,4)$ couplings. Then we present our predictions for the energies available at the RHIC and LHC. The total cross sections and several differential distributions are presented. Analysis of the distributions in the azimuthal angle $ϕ_{pp}$ between the transverse momenta of the outgoing protons may be used to disentangle $f_{1}$- and $η$-type resonances contributing to the same final channel. We find for the $f_{1}(1285)$ a total cross section $\sim 38$ $μ$b for $\sqrt{s} = 13$ TeV and a rapidity cut on the $f_{1}$ of $|{\rm y_{M}}| < 2.5$. We predict a much larger cross section for production of $f_{1}(1285)$ than for production of $f_{2}(1270)$ in the $π^{+}π^{-}π^{+}π^{-}$ decay channel for the LHC energies. This opens a possibility to study the $f_{1}(1285)$ meson in experiments planned at the LHC.

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arXiv2020

Production of $f_2(1270)$ meson in $pp$ collisions at the LHC via gluon-gluon fusion in the $k_t$-factorization approach

We calculate inclusive cross section for $f_2(1270)$ tensor meson production via color singlet gluon-gluon fusion in the $k_t$-factorization approach with unintegrated gluon distribution functions (UGDFs). The process may be potentially interesting in the context of searches for saturation effects. The energy-momentum tensor, equivalent to helicity-2 coupling, and helicity-0 coupling are used for the $g^* g^* \to f_2(1270)$ vertex. Two somewhat different parametrizations of helicity-2 and helicity-0 tensorial structure from the literature are used in our calculations. Some parameters are extracted from $γγ\to f_2(1270) \to ππ$ reactions. Different modern UGDFs from the literature are used. The results strongly depend on the parametrization of the $g^* g^* \to f_2(1270)$ form factor. Our results for transverse momentum distributions of $f_2$ are compared to preliminary ALICE data. We can obtain agreement with the data only at larger $f_2(1270)$ transverse momenta only for some parametrizations of the $g^* g^* \to f_2(1270)$ form factor. No obvious sign of the onset of saturation is possible. At low transverse momenta one needs to include also the $ππ$ final-state rescattering. The agreement with the ALICE data can be obtained by adjusting probability of formation and survival of $f_2(1270)$ in a harsh quark-gluon and multipion environment. The pomeron-pomeron fusion mechanism is discussed in addition and results are quantified.

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arXiv2020

Production of $f_{0}(980)$ meson at the LHC: Color evaporation versus color-singlet gluon-gluon fusion

The production of the $f_{0}(980)$ meson at high energies is not well understood. We investigate two different potential mechanisms for inclusive scalar meson production in the $k_t$-factorization approach: color-singlet gluon-gluon fusion and color evaporation model. The $γ^* γ^* \to f_0(980)$ form factor(s) can be constraint from the $f_0(980)$ radiative decay width. The $g^* g^* \to f_0(980)$ form factors are obtained by a replacement of $α_{\rm{em}}$ electromagnetic coupling constant by $α_{\rm{s}}$ strong coupling constant and appropriate color factors. The form factors for the two couplings are parametrized with a function motivated by recent results for scalar quarkonia. The differential cross sections are calculated in the $k_t$-factorization approach with modern unintegrated gluon distributions. Unlike for quarkonia it seems rather difficult to describe a preliminary ALICE data for inclusive production of $f_0(980)$ exclusively by the color singlet gluon-gluon fusion mechanism. Two different scenarios for flavor structure of $f_0(980)$ are considered in this context. We consider also mechanism of fusion of quark-antiquark associated with soft gluon emission in a phenomenological color evaporation model (CEM) used sometimes for quarkonium production. Here we use $k_t$-factorization version of CEM to include higher-order contributions. In addition, for comparison we consider also NLO collinear approach with $q \bar{q} q$ and $q \bar{q} g$ color octet partonic final states. Both approaches lead to a similar result. However, very large probabilities are required to describe the preliminary ALICE data. The pomeron-pomeron fusion mechanism is also discussed and results are quantified.

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arXiv2020

Searching for the odderon in $pp \to pp K^{+}K^{-}$ and $pp \to pp μ^{+}μ^{-}$ reactions in the $ϕ(1020)$ resonance region at the LHC

We explore the possibility of observing odderon exchange in the $pp \to pp K^{+}K^{-}$ and $pp \to pp μ^{+}μ^{-}$ reactions at the LHC. We consider the central exclusive production (CEP) of the $ϕ(1020)$ resonance decaying into $K^{+} K^{-}$ and $μ^{+}μ^{-}$. We compare the purely diffractive contribution (odderon-pomeron fusion) to the photoproduction contribution (photon-pomeron fusion). The theoretical results are calculated within the tensor-pomeron and vector-odderon model for soft reactions. We include absorptive corrections at the amplitude level. In order to fix the coupling constants for the photon-pomeron fusion contribution we discuss the reactions $γp \to ωp$ and $γp \to ϕp$ including $ϕ$-$ω$ mixing. We compare our results for these reactions with the available data, especially those from HERA. Our coupling constants for the pomeron-odderon-$ϕ$ vertex are taken from an analysis of the WA102 data for the $p p \to p p ϕ$ reaction. We show that the odderon-exchange contribution significantly improves the description of the $pp$ azimuthal correlations and the $dP_{t}$ "glueball-filter variable" dependence of $ϕ$ CEP measured by WA102. To describe the low-energy data more accurately we consider also subleading processes with reggeized vector-meson exchanges. However, they do not play a significant role at the LHC. We present predictions for two possible types of measurements: at midrapidity and with forward measurement of protons (relevant for ATLAS-ALFA or CMS-TOTEM), and at forward rapidities and without measurement of protons (relevant for LHCb). We discuss the influence of experimental cuts on the integrated cross sections and on various differential distributions. With the corresponding LHC data one should be able to get a decisive answer concerning the presence of an odderon-pomeron fusion contribution in single $ϕ$ CEP.

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arXiv2020

Searching for Odderon in Central Exclusive Processes at the LHC

There seem to be recently an evidence for $C = -1$ odderon exchange in proton-proton elastic scattering at high energies. Here we discuss three different central-exclusive-production processes $pp \to pp (ϕ\to K^{+}K^{-})$, $pp \to pp (ϕ\to μ^{+}μ^{-})$, and $pp \to pp ϕϕ\to pp K^{+}K^{-}K^{+}K^{-}$, as a possible source of information for soft odderon exchange. The theoretical results are calculated within the tensor-pomeron and vector-odderon model for soft reactions. We include absorptive corrections at the amplitude level. To describe the low-energy data measured in the past by the WA102 collaboration we consider also subleading processes with reggeized vector-meson exchanges and reggeons. We discuss possible evidences for odderon exchange at the low energies and try to make predictions at the LHC.

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arXiv2019

Extracting the pomeron-pomeron-$f_{2}(1270)$ coupling in the $p p \to p p π^{+} π^{-}$ reaction through angular distributions of the pions

We discuss how to extract the pomeron-pomeron-$f_2(1270)$ ($\mathbb{P} \mathbb{P} f_2(1270)$) coupling within the tensor-pomeron model. The general $\mathbb{P} \mathbb{P} f_2(1270)$ coupling is a combination of seven basic couplings (tensorial structures). To study these tensorial structures we propose to measure the central-exclusive production of a $π^+ π^-$ pair in the invariant mass region of the $f_2(1270)$ meson. An analysis of angular distributions in the $π^+ π^-$ rest system, using the Collins-Soper (CS) and the Gottfried-Jackson (GJ) frames, turns out to be particularly relevant for our purpose. For both frames the $\cosθ_{π^{+}}$ and $ϕ_{π^{+}}$ distributions are discussed. We find that the azimuthal angle distributions in these frames are fairly sensitive to the choice of the $\mathbb{P} \mathbb{P} f_2$ coupling. We show results for the resonance case alone as well as when the dipion continuum is included. We show the influence of the experimental cuts on the angular distributions in the context of dedicated experimental studies at RHIC and LHC energies. Absorption corrections are included for our final distributions.

hep-ph↗
arXiv2019

Searching for odderon exchange in exclusive $pp \to pp ϕϕ$ reaction

We discuss the possibility to use the $pp \to pp ϕϕ$ process in identifying the odderon exchange. So far there is no unambiguous experimental evidence for the odderon, the charge conjugation $C = -1$ counterpart of the $C= +1$ pomeron. Last year results of the TOTEM collaboration suggest that the odderon exchange can be responsible for a disagreement of theoretical calculations and the TOTEM data for elastic proton-proton scattering. Here we present recent studies for central exclusive production (CEP) of $ϕϕ$ pairs in proton-proton collisions. We consider the pomeron-pomeron fusion to $ϕϕ$ ($\mathbb{P}\mathbb{P} \to ϕϕ$) through the continuum processes, due to the $\hat{t}$- and $\hat{u}$-channel reggeized $ϕ$-meson, photon, and odderon exchanges, as well as through the $s$-channel resonance process ($\mathbb{P}\mathbb{P} \to f_{2}(2340) \to ϕϕ$). This $f_{2}$ state is a candidate for a tensor glueball. The amplitudes for the processes are formulated within the tensor-pomeron and vector-odderon approach. Some model parameters are determined from the comparison to the WA102 experimental data. The odderon exchange is not excluded by the WA102 data for high $ϕϕ$ invariant masses. The measurement of large $M_{ϕϕ}$ or $\rm{Y_{diff}}$ events at the LHC would therefore suggest presence of the odderon exchange.

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arXiv2019

Searching for odderon in exclusive reactions: $p p \to p p p {\bar p}$, $p p \to p p ϕϕ$ and $p p \to p p ϕ$

There seem to be recently an evidence for $C =$ -1 exchanges in $p p$ and $p \bar p$ elastic scattering at high energies. The analysis there is difficult as the two processes were not measured at the same (large) energies. Here we discuss three different exclusive processes given in the title as a possible source of information for odderon exchange. A sketch of the formalism is presented for each of the reactions. We consider low energy processes measured in the past by the WA102 collaboration and try to make predictions for the LHC. We discuss possible evidences at the low energies and try to make suggestions for the LHC.

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arXiv2019

Central exclusive diffractive production of $K^{+} K^{-} K^{+} K^{-}$ via the intermediate $ϕϕ$ state in proton-proton collisions

We present a study of the exclusive $pp \to pp K^{+} K^{-} K^{+} K^{-}$ reaction at high energies. We consider diffractive mechanisms with the intermediate $ϕϕ$ state with its decay into the $K^{+} K^{-} K^{+} K^{-}$ system. We include the $ϕ(1020)$ $\hat{t}/\hat{u}$-channel exchanges and the $f_{2}(2340)$ $s$-channel exchange mechanism. This $f_{2}$ state is a candidate for a tensor glueball. We discuss the possibility to use the $pp \to pp ϕϕ$ process in identifying the odderon exchange. An upper limit for the $\mathbb{P} \mathbb{O} ϕ$ coupling is extracted from the WA102 experimental data. The amplitudes for the processes are formulated within the tensor-pomeron and vector-odderon approach. We adjust parameters of our model to the WA102 data and present several predictions for the ALICE, ATLAS, CMS and LHCb experiments. Integrated cross sections of order of a few nb are obtained including the experimental cuts relevant for the LHC experiments. The distributions in the four-kaon invariant mass, rapidity distance between the two $ϕ$ mesons, special ``glueball filter variable'', proton-proton relative azimuthal angle are presented. The distribution in rapidity difference of both $ϕ$-mesons could shed light on the $f_{2}(2340) \to ϕϕ$ coupling, not known at present. We discuss the possible role of the $f_{0}(2100)$, $η(2225)$, and $X(2500)$ resonances observed in the $ϕϕ$ channel in radiative decays of $J/ψ$. Using typical kinematic cuts for LHC experiments we find from our model that the odderon-exchange contribution should be distinguishable from other contributions for large rapidity distance between the $ϕ$ mesons and in the region of large four-kaon invariant masses. At least, it should be possible to derive an upper limit on the odderon contribution in this reaction.

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