The cross sections for the glueball candidates production in quasi-real photon-photon collisions and on central diffraction processes, i.e. double Pomeron exchange, in heavy ion interactions at RHIC and LHC are computed. The rates for these distinct production channels are compared and they may be a fruitful approach to the investigation of glueballs.
We elaborate on the hypothesis that in high energy hadron hadron and nucleus nucleus collisions the lowest mass glueballs are copiously produced from the gluon rich environment especially at high energy density. We discuss the particular glueball decay modes: $0^{++}, 2^{++} \to K \bar{K}$ and $0^{++} \to π^{+} π^{-} \ell^{+} \ell^{-}$.
In this contribution we summarize recent results on the computation of cross sections for glueball candidates production in quasi-real photon-photon collisions and on central diffraction processes, i.e. double Pomeron exchange, in heavy ion interactions at the LHC are computed. In particular, we provide predictions for the production of exotic mesons f0(1500), f0(1710) and X(1835). The rates for these distinct production channels are compared.
The present discussion focusses on the dominant production of the 0++ glueball in central collisions in the suppressed yet observable channel 0++ --> pi+ pi- l+ l-.
Using flavor SU(3) symmetry for the light quarks validated by the available experimental data, we propose an intuitive way to hunt for a scalar glueball in B decays. In the presence of mixing between the glueball and ordinary scalar mesons, we explore the extraction of the mixing parameters. In particular, we discuss the implication from the recently available experimental data and show the sensitivities of B decays as a probe to the scalar structures. The future Super KEKB factory would allow access to establishing the mixing pattern among the scalars, and possibly allow one to disentangle th…
We review the current theoretical situation with regard to the anomalously large cross section for exclusive J/psi + eta_c production in e^+ e^- annihilation, as measured by BELLE Collaboration.
The existence and properties of the f0(1370) scalar meson are rather well established from data of antiproton annihilations at rest. However conflicting results from Central Exclusive Production (CEP) experiments of the last millennium and ignorance of data from antiproton annihilations at rest in H2 and D2 bubble chambers have generated doubts on the very existence of the f0(1370). Properties of π+π- pairs produced in central exclusive production (CEP) reactions observed in old data together with data collected in the current decade at high energy colliders permit to show that π+π- decays of …
We evaluate differential distributions for exclusive scalar $f_0(1500)$ production for $p \bar p \to N_1 N_2 f_0$ (FAIR@GSI) and $p p \to p p f_0$ (J-PARC@Tokai). Both QCD diffractive and pion-pion meson exchange current (MEC) components are included. Rather large cross sections are predicted. The pion-pion component, never discussed in the literature, dominates close to the threshold while the diffractive component takes over for larger energies. The diffractive component is calculated based on two-gluon impact factors as well as in the framework of Khoze-Martin-Ryskin approach proposed for d…
Heavy nuclei at collider energies are a source of high energy Weizsaecker-Williams photons. This photon flux may be utilized to study high energy photon-nucleus interactions. Here we concentrate on the coherent diffractive production of heavy vector mesons on nuclear targets and show how it probes the unintegrated glue of the nucleus in the saturation domain. We present predictions for rapidity distributions of exclusive coherent J/Psi and Upsilon mesons which can be measured by the ALICE experiment at the LHC.
The study of the properties of pion pairs emitted in pp Central Production Experiments (CEP) shows that a) scalar and tensor mesons production dominates at increasing energies and that 2++ production is suppressed by selecting events with low four momentum transfer square -t at both proton vertices and b) pion+pion- decays of the f0(1370) meson are directly observable as an isolated peak over a vanishing background between 1.1 and 1.6 GeV in measurements at high energies and low -t. Together with the measurements of the decay branching ratios of the f0(1370) into sigma sigma, rho rho, pion pio…
Production of $f_0(1710)$, a theoretical endeavor of pure scalar glueball state, is studied in detail from exclusive rare B decay within the framework of perturbative QCD. The branching fraction for $B^\pm \to K^{*\pm} f_0(1710) \to K^{*\pm} (K \bar K)$ is estimated to be about $8 \times 10^{-6}$, while for $B^\pm \to K^\pm f_0(1710) \to K^\pm (K \bar K)$ it is smaller by roughly an order of magnitude. With the accumulation of almost 1 billion $B \bar B$ pairs from the B{\tiny A}B{\tiny AR} and Belle experiments to date, hunting for a scalar glueball via these rare decay modes should be attain…
Using a bound-state model of weakly bound gluons for glueballs made of two gluons and a natural generalization of the perturbative QCD formalism for exclusive hadronic processes, we present results for glueball production in radiative J/psi, Upsilon decays into several possible glueball states, including L \not= 0 ones. We perform a detailed phenomenological analysis, presenting results for the more favored experimental candidates and for decay angular distributions.
We calculate the cross section for the exclusive production of J^{PC}=0^{++} glueballs G_0 in association with the J/psi in e^+e^- annihilation using the pQCD factorization formalism. The required long-distance matrix element for the glueball is bounded by CUSB data from a search for resonances in radiative Upsilon decay. The cross section for e^+e^- -> J/psi+ G_0 at sqrt{s}=10.6 GeV is similar to exclusive charmonium-pair production e^+e^- -> J/psi+h for h=eta_c and chi_{c0}, and is larger by a factor 2 than that for h=eta_{c}(2S). As the subprocesses gamma^* -> (c c-bar) (c c-bar) and gamma^…
The top-down holographic Witten-Sakai-Sugimoto model for low-energy QCD, augmented by finite quark masses, has recently been found to be able to reproduce the decay pattern of the scalar glueball candidate f0(1710) on a quantitative level. In this Letter we show that this model predicts a narrow pseudoscalar glueball heavier than the scalar glueball and with a very restricted decay pattern involving eta or eta' mesons. Production should be either in pairs or in association with eta(') mesons. We discuss the prospect of discovery in high-energy hadron collider experiments through central exclus…
The exclusive $K^+$ meson production in a proton-nucleus collision, leading to two body final states, is investigated in a fully covariant two-nucleon model based on the effective Lagrangian picture. The explicit kaon production vertex is described via creation, propagation and decay into relevant channel of $N^*$(1650), $N^*$(1710) and $N^*$(1720) intermediate baryonic states in the initial collision of the projectile nucleon with one of its target counterparts which is modeled by the one-pion exchange process. The calculated cross sections show strong sensitivity to the medium effects on pio…
Decays into two charged pions of the f0(1370) are the main source of an isolated structure localized between 1.2 and 1.5 GeV in the two charged pions mass spectrum measured in pp Central Exclusive Production (CEP) at 200 GeV at very low four momentum transfer ltl by the STAR experiment. These data confirm in the two charged pions decay channel the existence of the f0(1370) as an isolated well identified structure previously observed in K+K-, KsKs, 4 charged pions, two charged and two neutral pions and 4 neutral pions decays measured in antiproton annihilations at rest. The ensemble of these da…
The cross section for exclusive $π^+π^-$ and $π^0π^0$ meson pairs production in peripheral ultrarelativistic heavy-ion collisions is calculated at the energy available at the CERN Large Hadron Collider, i.e., $\sqrt{s_{NN}}=3.5$ TeV. The cross section for elementary $γγ\toππ$ process is calculated with the help of the pQCD Brodsky-Lepage approach with the distribution amplitude used recently to describe the pion transition form factor measured by the BaBar Collaboration.
The flavour independence hypothesis for (tensor) glueball decays into exclusive final states is not ruled out by the existing data. A new methodology for testing its validity and accuracy is proposed in the framework of a particular mixing scheme. As an important consequence of our analysis, a relative factor of the order of 10 must be experimentally observed for the ratio $Γ(Θ\rightarrow K\bar{K})Γ(Θ\rightarrow ππ)$, if flavour independence indeed is valid.
Exclusive Double Diffractive Events (EDDE) are analysed as the source of information about the central system. Experimental possibilities for exotic particles searches are considered. From the reggeized tensor current picture some azimuthal angle dependences were obtained to fit the data from WA102 experiment and to make predictions for LHC collider.
A simple model based on Regge approach is proposed for description of the central exclusive production (CEP) of the light tensor glueball lying on the Regge trajectory of the soft Pomeron.
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 co…
In this paper, it is shown that in hadron-nucleus and nucleus-nucleus collisions, the main source for central exclusive diffractive Higgs production is photon-photon fusion. At the LHC energy, the total cross section for this process is about 0.6 pb (for proton-gold scattering), and 3.9 nb (for gold-gold collision) while the gluon-gluon fusion leads to the value of the cross section for CED Higgs production which is about 0.1 nb and 3.9 pb respectively.
The automated generation of arbitrary exclusive final states produced via photon fusion in ultraperipheral high-energy collisions of protons and/or nuclei is implemented in the MadGraph5_aMC@NLO and HelacOnia Monte Carlo codes. Cross sections are calculated in the equivalent photon approximation using $γ$ fluxes derived from electric dipole and charge form factors, and incorporating hadronic survival probabilities. Multiple examples of $γγ$ cross sections computed with this setup, named gamma-UPC, are presented for proton-proton, proton-nucleus, and nucleus-nucleus ultraperipheral collisions (…
We show that gluon saturation gives rise to a strong modification of the scaling in both the nuclear mass number $A$ and the virtuality $Q^2$ of the vector meson production cross-section in exclusive deep-inelastic scattering off nuclei. We present qualitative analytic expressions for how the scaling exponents are modified as well as quantitative predictions that can be tested at an Electron-Ion Collider.
The cross sections for exclusive muon pair production in nucleus - nucleus collisions are calculated and several differential distributions are shown. Realistic (Fourier transform of charge density) charge form factors of nuclei are used and the corresponding results are compared with the cross sections calculated with monopole form factor often used in the literature and discussed recently in the context of higher-order QED corrections. Absorption effects are discussed and quantified. The cross sections obtained with realistic form factors are significantly smaller than those obtained with th…
This compact review about gluonium focuses on a slate of theoretical efforts; among the many standing works, I have selected several that are meant to assist in the identification, among ordinary mesons, of the few Yang-Mills glueball configurations that populate the energy region below 3 GeV. This includes $J/ψ$ radiative and vector-meson decays, studies of scalar meson mixing, of high-energy cross sections via the Pomeron and the odderon, glueball decays, etc. The weight of accumulated evidence seems to support the $f_0(1710)$ as having a large (and the largest) glueball component among the …
In this letter we update our predictions for exclusive $J/Ψ$ and $Υ$ photoproduction in proton-proton and nucleus - nucleus collisions at the Run 2 LHC energies obtained with the color dipole formalism and considering the impact parameter Color Glass Condensate model (bCGC) for the forward dipole - target scattering amplitude. A comparison with the LHCb data on rapidity distributions and photon - hadron cross sections is presented. Our results demonstrate that the current data can be quite well described by the bCGC model, which takes into account nonlinear effects in the QCD dynamics and repr…
In this contribution we report on the investigations of the exclusive production of J/psi and psi(2S) states in proton-proton and nucleus-nucleus reactions at the LHC using the theoretical framework of light-cone dipole formalism.
We study the possibility of the scalar charmonium and glueball mixing in $e^+ e^-$ annihilation at $\sqrt{s}=10.6$ GeV. The effects can be used to explain the unexpected large cross section ($12\pm 4$ fb) and the anomalous angular distribution ($α= -1.1^{+0.8}_{-0.6}$) of the exclusive $e^+e^-\to J/ψχ_{c0}$ process observed by Belle experiments at KEKB. We calculate the helicity amplitudes for the process $e^+ e^- \to J/ψH(0^{++})$ in NRQCD, where $H(0^{++})$ is the mixed state. We present a detailed analysis on the total cross section and various angular asymmetries which could be useful to r…
We present results of an updated calculation of the 2p2h (two particle two hole) contribution to the neutrino-induced charge-current cross section. We provide also some exclusive observables, interesting from the point of view of experimental studies, e.g. distributions of momenta of the outgoing nucleons and of available energy, which we compare with the results obtained within the NEUT generator. We also compute, and separate from the total, the contributions of 3p3h mechanisms. Finally, we discuss the differences between the present results and previous implementations of the model in MC ev…
We present a full kinematic analysis of neutrino-nucleus charged current quasielastic interactions based on the Local Fermi Gas model and the Random PhaseApproximation. The model was implemented in the NEUT Monte Carlo framework, which allows us to investigate potentially measurable observables, including hadron distributions. We compare the predictions simultaneously to the most recent T2K and MINERvA charged current (CC) inclusive, CC0$π$ and transverse kinematic-imbalance variable results. We pursuit a microscopic interpretation of the relevant reaction mechanisms, with the aim of achieving…
A semiclassical theory of high energy scattering based on interrupted tunneling (instantons) or QCD sphaleron production has been recently developed to describe the growing hadronic cross section and properties of the soft Pomeron. In this work we address double-pomeron processes in this framework for the first time. We specifically derive the cross section for central production of parity even and odd clusters, scalar and pseudoscalar glueballs, and $η'$ in parton-parton scattering at high energy. We show that the specific dependence of the production cross section on all its kinematical vari…
Preliminary estimates suggest that excess dimuon production with invariant mass in the range 1.5 -- 2.5 GeV in nucleus-nucleus collisions can be explained on the basis of $η_c$ production. This appears to be consistent with all the peripheral and central collision data with various nuclei such as S-U at 200 GeV/nucleon except for the central collision data on Pb-Pb at 158 GeV/nucleon. Some explanations based on glueball production for Pb-Pb data are discussed.
The exclusive $Υ$ photoproduction in proton-proton and proton - nucleus collisions at LHC energies is investigated using the color dipole formalism and considering different models for the $Υ$ wave function and forward dipole - target scattering amplitude. Our goal is to update the color dipole predictions and estimate the theoretical uncertainty present in these predictions. We present predictions for the kinematical ranges probed by the ALICE, CMS and LHCb Collaborations.
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.
We provide a universal expression of cross sections for the exclusive vector meson production and Deeply Virtual Compton Scattering (DVCS) in photon-proton and photon-nucleus interactions based on the geometric scaling phenomenon. The theoretical parameterization based on the scaling property depends only on the single variable $τ_A = Q^2/Q_{\mathrm{sat}}^2$, where the saturation scale, $Q_{\mathrm{sat}}$, drives the energy dependence and the corresponding nuclear effects. This phenomenological result describes all available data from DESY-HERA for $ρ,\,ϕ,\,J/ψ$ production and DVCS measurement…
Evaluating the ratio of the exclusive vector meson photoproduction to inclusive hadron/jet production cross section in ultraperipheral heavy ion collisions
Universidade Federal de Santa Catarina(圣卡塔琳娜联邦大学);Federal University of Rio Grande do Sul (UFRGS)(南里奥格兰德联邦大学)
By studying the $η_c$ exclusive decay to double glueballs, we introduce a model to mimic phenomenologically the gluon-pair-vacuum interaction vertices, namely the $0^{++}$ model. Based on this model, we study glueball production in pseudoscalar quarkonium decays, explicitly $η_c \to f_0(1500)η(1405)$, $η_b\to f_0(1500)η(1405)$ and $η_b\to f_0(1710)η(1405)$ processes. Among them $f_0(1500)$ and $f_0(1710)$ are well-known scalars possessing large glue components and $η(1405)$ is a potential candidate for pseudoscalar glueball. The preliminary calculation results indicate that these processes are…
Decipher the nature of glueball candidate $X(2370)$
Center for High Energy Physics, Peking University(北京大学高能物理中心);School of Physics and Electronic Technology, Liaoning Normal University(辽宁师范大学物理与电子科技学院);Center for Theoretical and Experimental High Energy Physics, Liaoning Normal University(辽宁师范大学理论与实验高能物理中心);School of Physical Sciences, University of Chinese Academy of Sciences(中国科学院大学物理科学学院)
We investigate the exclusive photoproduction of $J/ψ$-mesons in ultraperipheral heavy ion collisions in the color dipole approach. We first test a number of dipole cross sections fitted to inclusive $F_2$-data against the total cross section of exclusive $J/ψ$-production on the free nucleon. We then use the color-dipole formulation of Glauber-Gribov theory to calculate the diffractive amplitude on the nuclear target. The real part of the free nucleon amplitude is taken into account consistent with the rules of Glauber theory. We compare our results to recent published and preliminary data on e…
We investigate the theoretical uncertainty on the predictions for the photoproduction of $ρ$ and $J/Ψ$ states in nucleus-nucleus collisions at Run 2 LHC energies using the Color Dipole formalism. The results for rapidity distributions and total cross sections are presented. Moreover, we compare directly the theoretical results to the recent preliminary data from ALICE collaboration on $ρ$ production in $PbPb$ collisions at central rapidity.
Using the framework of collinear factorization in perturbative QCD (pQCD), we analyze the recent data of the LHCb and ALICE collaborations on exclusive photoproduction of J/ψ in ultraperipheral pp and AA collisions, respectively. We demonstrate that the simultaneous analysis of the proton and Pb data allows us to reduce the ambiguity of the pQCD description of the $γp \to J/ψp$ and $γA \to J/ψp$ cross sections and, hence, to place additional constraints on the gluon distributions in the nucleon and nuclei at small x. We also make predictions for the cross section of coherent exclusive photopro…
The cross sections for exclusive $D^+D^-$ and $D^0 \bar {D^0}$ meson pair production in peripheral nucleus - nucleus collisions are calculated and several differential distributions are presented. The calculation of the elementary $γγ\to D \bar D$ cross section is done within the heavy-quark approximation and in the Brodsky- Lapage formalism with distribution amplitudes describing recent CLEO data on leptonic $D^+$ decay. Realistic (Fourier transform of charge density) charge form factors of nuclei are used to generate photon flux factors. Absorption effects are discussed and quantified. The c…
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. …
We discuss central exclusive diffractive production of light mesons in the reactions $pp \to ppπ^{+}π^{-}$ and $pp \to ppK^{+}K^{-}$. The calculation is based on a tensor-pomeron approach. We include a purely diffractive dipion continuum, and the scalar $f_{0}(980)$, $f_{0}(1500)$, $f_{0}(1710)$ and tensor $f_{2}(1270)$, $f'_{2}(1525)$ resonances decaying into pseudoscalar meson pairs. We include also photoproduction mechanisms for the nonresonant (Drell-Söding) and the $ϕ(1020)$ resonance contributions. The theoretical results are compared with existing CDF experimental data and predictions f…
We describe the physics and computational power of GRANIITTI Monte Carlo event generator, a new fully multithreaded engine designed for high energy diffraction, written in modern C++. The emphasis is especially on the low-mass domain of central exclusive processes of the S-matrix, where exotic QCD phenomena such as glueballs are expected and holographic dualities with gravity may be tested. The generator includes photon-photon, photon-pomeron, pomeron-pomeron, Durham QCD model and Tensor pomeron model type scattering amplitudes and advanced spin analysis tools. The generator combines a full pa…
We evaluate differential distributions for exclusive scalar $f_0(1500)$ meson (glueball candidate) production. Both QCD diffractive, pion-pion meson exchange current (MEC) components as well as double-diffractive mechanism with intermediate pionic loop are calculated. The pion-pion component, which can be reliably calculated, dominates close to the threshold while the diffractive component may take over only for larger energies. At the moment only upper limit for the QCD-diffractive component can be obtained. The diffractive component is calculated based on the Khoze-Martin-Ryskin approach pro…
Exclusive vector meson production reactions such as $Au + Au \to Au + Au + V$, where $V=ρ, ω, ϕ$ or $J/ψ$ can proceed through photon-Pomeron and photon-meson interactions. Photons from the electromagnetic field of one nucleus interact coherently with the other nucleus. Photonuclear cross sections are scaled from $γp$ data, and convoluted with the photon spectrum to find the exclusive rates. The cross sections at the RHIC and LHC heavy ion colliders are huge, 10% of the total hadronic cross section at RHIC, and 50% at LHC. These accelerators may be useful as vector meson factories. With iodine …
The analysis of the recent charged-current neutrino-nucleus scattering cross sections measured by the ArgoNeuT Collaboration requires relativistic theoretical descriptions also accounting for the role of final-state interactions. In this work, we evaluate differential neutrino-nucleus cross sections with the relativistic Green's function model, where final-state interactions are described in the inclusive scattering consistently with the exclusive scattering using a complex optical potential. The sensitivity to the parameterization adopted for the phenomenological optical potential is discusse…
We point out that the LDMX (Light Dark Matter eXperiment) detector design, conceived to search for sub-GeV dark matter, will also have very advantageous characteristics to pursue electron-nucleus scattering measurements of direct relevance to the neutrino program at DUNE and elsewhere. These characteristics include a 4-GeV electron beam, a precision tracker, electromagnetic and hadronic calorimeters with near 2$π$ azimuthal acceptance from the forward beam axis out to $\sim$40$^\circ$ angle, and low reconstruction energy threshold. LDMX thus could provide (semi)exclusive cross section measurem…
The analysis of the recent charged-current neutrino-nucleus scattering cross sections measured by the MiniBooNE Collaboration requires relativistic theoretical descriptions also accounting for the role of final-state interactions. In this work, we evaluate differential antineutrino-nucleus cross sections with the relativistic Green's function model, where the final-state interactions are described in the inclusive scattering consistently with the exclusive scattering using a complex optical potential. The sensitivity to the parameterization adopted for the phenomenological optical potential is…
In this article, we study the fully differential observables of exclusive production of heavy (charm and bottom) quark pairs in high-energy ultraperipheral $pA$ and $AA$ collisions. In these processes, the nucleus $A$ serves as an efficient source of the photon flux, while the QCD interaction of the produced heavy-quark pair with the target ($p$ or $A$) proceeds via an exchange of gluons in a color singlet state, described by the gluon Wigner distribution. The corresponding predictions for differential cross sections were obtained by using the dipole $S$-matrix in the McLerran--Venugopalan sat…
We study the photoproduction of exclusive $2π^+2π^-$ mesons in ultra-peripheral heavy-ion collisions at RHIC and LHC energies. Predictions in photon-nucleus interactions are calculated for various resonances at central and forward rapidities. The recent H1 preliminary data are utilized to improve the description of the poorly known $γp \to 4π^\pm p$ process. We present the comparisons of our results to the available STAR data at RHIC, and made predictions for LHC energies.
We analyze the experimental data on the inclusive double differential cross section by neutrinos charged current, measured by T2K, with the same model which was successful for the MiniBooNE quasielastic cross sections. As in our previous analysis the multinucleon component is needed in order to reproduce the data. For the total cross section our evaluation is smaller than the SciBooNE data above 1 GeV. This indicates the opening of a new channel not included in our evaluation, presumably the two pion emission channel. We also check that our description holds for the exclusive single pion produ…
Central exclusive diffractive (CED) production of meson resonances potentially is a factory producing new particles, in particular a glueball. The produced resonances lie in trajectories with vacuum quantum numbers, essentially on the pomeron trajectory. A tower of resonance recurrences, the production cross section and the resonances widths are predicted. A new feature is the form of the non-linear pomeron trajectory, producing resonances (glueballs) with increasing widths. At LHC energies, in the nearly forward direction the $t$-channel both in elastic, single or double diffraction dissociat…