Multiplicity dependence of $χ_{c}$ and $χ_{b}$ meson production
Marat Siddikov, Iván Schmidt
备注：
14 pages, 9 figures. This paper is a sequel to our earlier publications arXiv:1910.13579, arXiv:2003.13768 and arXiv:2008.12446 dedicated to multiplicity dependence of quarkonia and open heavy flavour meson production
In this paper we analyze in detail the production of the $χ_{c}$ and $χ_{b}$ mesons in $pp$ collisions. Using the color dipole framework, we estimated the cross-sections in the kinematics of ongoing and forthcoming experiments, and found that our estimates are in reasonable agreement with currently available experimental data. We also analyzed the dependence on multiplicity of co-produced hadrons and found that it is significantly milder than that of $S$-wave quarkonia. We expect that the experimental confirmation of this result could constitute an important test of our understanding of multiplicity enhancement mechanisms in the production of different quarkonia states.
In this paper we study the electroproduction of open heavy flavor $D$- and $B$-mesons in the kinematics of future $ep$ colliders, such as the Electron Ion Collider (EIC), the Large Hadron electron Collider (LHeC) and the Future Circular Collider (FCC-he). We study in detail the dependence of the cross-sections on multiplicity of co-produced hadrons, in view of its possible sensitivity to contributions from multipomeron contributions, and discuss different observables which might be used for its study. According to our theoretical expectations, in $ep$ collisions the multipomeron contributions …
We study the influence of the meson cloud of the nucleon on predictions of the Monte Carlo Glauber model for the charged particle multiplicity density at mid-rapidity in $AA$ collisions. We find that for central $AA$ collisions the meson cloud can increase the multiplicity density by $\sim 16-18$\%. The meson-baryon Fock component reduces the required fraction of the binary collisions by a factor of $\sim 2$ for Au+Au collisions at $\sqrt{s}=0.2$ TeV and $\sim 1.5$ for Pb+Pb collisions at $\sqrt{s}=2.76$ TeV.
In this paper we propose an approach which demonstrates the dependence of quarkoni production on the multiplicity of the accompanying hadrons. Our approach is based on the three gluons fusion mechanism, without assuming the multiplicity dependence of the saturation scale. We show, that we describe the experimental data, which has a dependence that is much steeper than the multiplicity of the hadrons.
The origin of the erraticity behaviour observed recently in the experiment is studied in some detail. The negative-binomial distribution is used to fit the experimental multiplicity distribution. It is shown that, with the multiplicity distribution taken into account, the experimentally observed erraticity behaviour can be well reproduced using a flat probability distribution. The dependence of erraticity behaviour on the width of multiplicity distribution is studied.
The selection of $η$ mesons with a high efficiency and a high purity can be important in the formation of statistically significant invariant mass spectra in the reconstruction of short-lived particles such as $η' \rightarrow π^{+} π^{-} η$. In this study, a cut-based standard method and a Ranking method to reduce combinatorial background in the reconstruction of $η\rightarrow γγ$ decays in high multiplicity hadronic events are presented. By using recorded ALEPH data and fully simulated events, the performances of the methods are compared. Results show that the Ranking method yields significan…
Predictions of a thermodynamical model of hadron production for multiplicity distributions in $e^+e^-$ annihilations at LEP and PEP-PETRA centre of mass energies are shown. The production process is described as a two-step process in which primary hadrons emitted from the thermal source decay into final observable particles. The final charged tracks multiplicity distributions turn out to be of Negative Binomial type and are in quite good agreement with experimental observations. The average number of clans calculated from fitted Negative Binomial coincides with the average number of primary ha…
We report the multiplicity dependence of charged particle productions for $π^{\pm}$, $K^{\pm}$, $p$, $\overline{p}$ and $ϕ$ meson at $|y| < 1.0$ in p+p collisions at $\sqrt{\rm s}$ = 200 GeV with $\rm PYTHIA$ simulation. The impact of parton multiple interactions and gluon contributions is studied and found to be possible sources of the particle yields splitting as a function of $p_T$ with respect to multiplicity. No obvious particle species dependence for the splitting is observed. The multiplicity dependence on ratios of $K^-/π^-$, $K^+/π^+$, $\overline{p}/π^-$, $p/π^+$ and $Λ/K^{0}_{s}$ in …
In this paper we analyze in detail the production of strangeness in proton-proton collisions in the kinematics of large transverse momenta $p_{T}$ of produced hadrons. Using the color dipole framework, we estimated the production cross-sections for kaons, and demonstrated that the shapes of the $p_{T}$-dependence are in agreement with available experimental data. We also analyzed the self-normalized yields of strange hadrons as a function of multiplicity of co-produced hadrons, and found that the predictions are in agreement with the faster-than-linear growth seen in experimental data. Our des…
The dependence of the production of the $X(3872)$ meson on the hadron multiplicity in $pp$ collisions has been used as evidence against $X$ being a charm-meson molecule. The argument is based in part on the incorrect assumption that the cross section for the breakup of $X$ by scattering with comovers can be approximated by a geometric cross section inversely proportional to the binding energy of $X$. The breakup cross section should instead be approximated by the probability-weighted sum of the cross sections for the scattering of comoving pions from the charm-meson constituents of $X$, which …
We propose that the charged-particle multiplicity dependence of the charm-baryon-to-meson ratio observed in high-energy $pp$ collisions can be explained by canonical treatment of quantum charges in the statistical hadronization model (SHM). Taking the full particle listings of PDG complemented by additional charm-baryon states from relativistic quark model predictions, we evaluate the canonical partition function and the charm-hadron chemical factors that measure the canonical suppression arising from the requirement of strict conservation of quantum charges. We demonstrate that, while charm n…
We present a formalism for studying the exclusive production or decay of mesons with any value of the internal orbital angular momentum L. As an application, we discuss the production of meson pairs (involving tensor and pseudotensor mesons) in photon-photon collisions.
At LHC energies, the charged-particle multiplicity dependence of particle production is a topic of considerable interest in $pp$ collisions. It has been argued that multiple partonic interactions play an important role in particle production mechanisms, not only affecting the soft processes but also the hard processes. Recently, ALICE has measured $J/ψ$ production as a function of charged-particle multiplicity to study the correlation between soft and hard processes. In this contribution, we present the $J/ψ$ production versus multiplicity for $pp$ and $p-Pb$ collisions measured by ALICE. We c…
In this work, using the covariant light front approach with conventional vertex functions, we estimate the production rates of $D$-wave charmed/charmed-strange mesons via $B_{(s)}$ semileptonic decays. Due to these calculated considerable production rates, it is possible to experimentally search for $D$-wave charmed/charmed-strange mesons via the semileptonic decays, which may provide extra approach to explore $D$-wave charmed/charmed-strange mesons.
We demonstrate that the azimuthal dependence of central meson production in hadronic collisions, when suitably binned, provides unambiguous tests of whether the Pomeron couples like a conserved vector-current to protons. We discuss the possibility of discriminating between q-qbar and glueball production in such processes. Our predictions apply also to meson production in tagged two-photon events at electron--positron colliders and to vector-meson production in ep collisions at HERA.
We study the production of spin-one mesons in high-energy heavy-ion collisions with peripheral kinematics in the framework of QED. The cross sections of the production of a single vector meson and of two different ones are presented. The explicit dependence on the virtuality of the intermediate vector meson is obtained within a quark model. The effect of reggeization of the intermediate vector meson state in the case of the production of two vector mesons is taken into account.
The two parameters Weibull function is used to describe the charged particle multiplicity distribution in $e^{+}e^{-}$ collisions at the highest available energy measured by TASSO and ALEPH experiments. The Weibull distribution has wide applications in naturally evolving processes based on fragmentation and sequential branching. The Weibull model describes the multiplicity distribution very well, as particle production processes involve QCD parton fragmentation. The effective energy model of particle production was verified using Weibull parameters and the same was used to predict the multipli…
The evaluation of the number of ways we can distribute energy among a collection of particles in a system is important in many branches of modern science. In particular, in multiparticle production processes the measurements of particle yields and kinematic distributions are essential for characterizing their global properties and to develop an understanding of the mechanism for particle production. We demonstrate that energy distributions are connected with multiplicity distributions by their generating functions.
We compute the approximate cross section $σ_n^{(0)}$ for producing $n-2$ {\it resolved} gluons in a gluon-gluon collision, using the Parke-Taylor formula regularized in a Lorentz invariant manner. We find, in double leading logarithm approximation, that \[ σ_{n}^{(0)} \approx \frac{1}{s} \left( \frac{N_cα_s}{2 π\sqrt{12}} \ \ln^{2} (s/s_{cut})\right)^{n-2}\ \ , \] where $\sqrt{s_{cut}}$ is the minimum invariant mass for a resolved gluon pair. There is no factor of $1/(n-2)!$ multiplying the expression. We present additional numerical results, and comment on their implications for perturbative …
Oscillations of cumulant moments of multiplicity distributions at high ranks, evolution of factorial moments with bin sizes (intermittency, fractality), zeros of the truncated generating functions of multiplicity distributions, and charge fluctuations in multiparticle production processes are discussed.
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The cross sections of the scalar meson $f_0(980)$, $a_0(980)$ and $σ(600)$ production in collision of electron and positron beams were calculated. The two-photon decays of the scalar mesons, obtained in the framework of the Nambu-Jona-Lasinio model, were used. The quark and meson loops were taken into account.
The pion Bose-Einstein correlation parameters determined by OPAL show a weak dependence on pion multiplicity. We argue that the observed increase of the interaction radius, and the decrease of the chaoticity parameter could be due to an increasing fraction of other mesons at high multiplicities.
I discuss recent progress in the theory of exclusive meson production and Compton scattering, focusing on hard-scattering factorization and on the dipole formalism.
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A review is presented of diffractive vector meson production at HERA, with stress on the investigation of ``hard'' features and comparisons with theoretical predictions based on perturbative QCD approaches.
I discuss mechanisms of exclusive production of mesons at high energies. Some illustrative examples for the FNAL Tevatron and CERN LHC as well as for lower energies are shown.
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We estimate the production cross sections for $η_c$ and $η_b$ mesons via pomeron-pomeron fusion in peripheral heavy-ion collisions. Total and elastic PP cross sections are calculated in an equivalent pomeron approximation.
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We point out that hard exclusive production of tensor mesons $f_2(1270)$ with helicity $λ=\pm 2$ is dominated by the gluon component in the meson wave function and can be used to determine gluon admixture in tensor mesons in a theoretically clean manner. We present a detailed analysis of the tensor meson distribution amplitudes and calculate the transition form factor $γ+γ^*\to f_2(1270)$ for one real and one virtual photon.
Charmed meson production in semi-inclusive deep inelastic scattering is investigated in the color dipole formalism. The transverse momentum distributions are calculated. We find good agreement with the H1 data using a hard fragmentation function.
Experimental results from HERA on diffractive vector meson production and their theoretical interpretation within microscopic QCD are reviewed with an emphasis on the BFKL color dipole and kt-factorization approaches.
We summarise recent progress in the computation of helicity amplitudes for diffractive vector meson production at large momentum transfer and their comparison to data collected at the HERA collider.
We analyze decay spin-density matrix elements of $K^*$ and $D^*$ vector mesons and find that the corresponding vector meson decay distributions are sensitive to the production mechanisms. This suggests that the measurement of these quantities can be used to unravel the production mechanisms.
The multiplicity of heavy quarks from gluon splitting in e+e- annihilation has now been theoretically calculated and experimentally measured at LEP. However, the experimental measurement requires theoretical input for the shape of the multiplicity with respect to an event shape. In this paper we calculate the multiplicity of heavy quarks from gluon splitting in e+e- annihilation as a function of the heavy jet mass of the event, to next-to-leading logarithmic accuracy. We compare our result with Monte Carlo predictions.
Studies on the decay and production of $B_c (B^*_c)$ meson are briefly reviewed. Considering RUN-II of Tevatron and the schedule of LHC, the theoretical studies of $B_c$ meson will jump to a new stage not only for itself but also to implement the studies of the heavy quarkonia etc.
The double pomeron exchange contributions to the central inclusive and exclusive chi_c0 and chi_b0 mesons production in the Bialas-Landshoff approach are calculated. We find the model to be consistent with the preliminary CDF upper limit on double diffractive exclusive chi_c0 production cross section.
Estimation of multiplicity of muons and pions production at high energy proton-nuclei collisions is given. Both QED and QCD contributions are considered for peripheral kinematics of muon pair and $σ$-meson production, keeping in mind it's final conversion to muons. An attempt to explain the excess of positive charged muons compared to negative one in cosmic muon showers is given. We derive the dependence of cross-section of $n$ pairs as a function of $n$ at large n as $d^n(n!n^2)^{-1}$.
The $B_c$--meson production cross section was calculated in the perturbative QCD. Various distributions of the charged leptons from the $B_c \to l νJ/ψ(\to l^+ l^-)$ decay were obtained. The $B_c$--meson mass measurement from such decays is also discussed.
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In this paper we study the dependence of Bose-Einstein correlations on the multiplicity of an event. We found that events with large multiplicity, stem from the production of several parton showers, while the additional production of small multiplicity in the central rapidity region (central diffraction), gives a negligible contribution due to emission of soft gluons, that leads to the Sudakov suppression of the exclusive production of two gluon jets. Hence, the Bose-Einstein correlation is the main source of the azimuthal angle correlations which generates $v_n$ with odd and even $n$. We foun…
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I review some recent developments in the QCD description of elastic vector meson production, focusing on issues like the meson wave function, the gluon density in the proton, factorisation, the use of parton-hadron duality and the nonperturbative vacuum.
We study the production asymmetry of charm versus anticharm mesons in photon-proton interactions. We consider photon gluon fusion plus higher order corrections in which light quarks through vector meson-proton interactions contribute to the cross section. Non perturbative effects are included in terms of a recombination mechanism which gives rise to a production asymmetry.
We discuss role of absorbtion and antishadowing in particle production. Antishadowing, which leads to domination of elastic scattering at high energies, appears to be consistent with growth of mean multiplicity in hadronic collisions. Moreover, we demonstrate possibility to reproduce power-like energy behavior of the mean multiplicity in the model with antishadowing and discuss physical implications of such behavior for the hadron structure.
Inclusive production of light mesons ($π^0$, $η$, $π^{\pm}$, $K^{\pm}$ ) at the Tevatron is considered in QCD to next-to-leading order in the formalism of fragmentation functions. We present various distributions of phenomenological interest, along with a new set of $K$ mesons fragmentation functions.
We present a simple gluon production picture which is based on the McLerran-Venugopalan model and gluon BFKL evolution in relativistic heavy ion collision. Results for the multiplicity and transverse energy distribution in both the central and forward rapidity regions for gluon production in early stages of heavy ion collisions at the LHC are given. Finally, we provide a general qualitative discussion of the consequences of the forward rapidity behavior of produced gluons.
We discuss the dependence of J/ψ production on the charged particle multiplicity in proton-proton collisions at LHC energies. We show that, in the framework of parton saturation or string interaction models, the hard J/ψ production exhibits a significant growth with the multiplicity, which is stronger than linear in the high density domain. This departure from linearity, that should affect any hard observable, applies for high multiplicity proton-proton collisions in the central rapidity region and is a consequence of the parton saturation or the strong interaction among colour ropes that take…
