Heavy Hadron Production Research Articles

Doubly heavy hadron production in ultraperipheral collision

We study the double heavy baryon ΞQQ′ and tetraquark TQQ production through photon-photon and photon-gluon fusion via ultraperipheral collisions at the LHC and Future Circular Collider (FCC) within the framework of nonrelativistic QCD factorization formalism. Various ion-ion collisions are taken into account, two cc(bb)-diquark configurations ([cc(bb),S31−3¯] and [cc(bb),S10−6]) and four bc-diquark configurations ([bc,S31−3¯], [bc,S31−6], [bc,S10−3¯], and [bc,S10−6]) are considered in the calculation. Numerical results indicate that the [cc,S31−3¯] diquark provides dominant contribution for Ξcc (Tcc) production, and a considerable number of Ξcc (Tcc) can be produced. Because the event topologies for ultraperipheral collision are very clear, the background from various QCD interactions can be suppressed, hence the experimental investigation for Ξcc and Tcc is feasible. The productions for Ξbc/bb are also discussed, leaving only a slight possibility for Ξbc through photon-gluon fusion with ultraperipheral collisions at the FCC. Published by the American Physical Society 2024

Predictions for neutrinos and new physics from forward heavy hadron production at the LHC

Scenarios with new physics particles feebly interacting with the Standard Model sector provide compelling candidates for dark matter searches. Geared with a set of new experiments for the detection of neutrinos and long-lived particles the Large Hadron Collider (LHC) has joined the hunt for these elusive states. On the theoretical side, this emerging physics program requires reliable estimates of the associated particle fluxes, in particular those arising from heavy hadron decays. In this work, we provide state-of-the-art QCD predictions for heavy hadron production including radiative corrections at next-to-leading order and using parton distribution functions including small-x resummation at next-to-leading logarithmic accuracy. We match our predictions to parton showers to provide a realistic description of hadronisation effects. We demonstrate the utility of our predictions by presenting the energy spectrum of neutrinos from charm hadron decays. Furthermore, we employ our predictions to estimate, for the first time, FASER’s sensitivity to electrophilic ALPs, which are predominantly generated in beauty hadron decays.

Heavy hadron production through pair annihilation in the ordinary and noncommutative SM

Different processes have been yet studied in the noncommutative standard model (NCSM) and various limits on the scale of noncommutative parameter have been determined. In the present work we, for the first time, investigate the production process of heavy hadrons through pair annihilation in the NCSM using Seiberg-Witten maps to the second-order of noncommutative parameter Θμν. Having experimental data from Belle and OPAL Collaborations for inclusive production of B-mesons we will determine a low limit for the noncommutative scale ΛNC. The effects of noncommutativity will be imposed both on the differential cross section at the parton level (e+e−→qq¯) and the fragmentation function of q/q¯→B so that the limit ΛNC>1.10 TeV is determined. Using analytical result for the pair annihilation cross section we will also predict the production rate of Bc mesons in future electron-positron international linear collider (ILC).

Coalescence plus fragmentation approach for the hadronization mechanism of heavy hadrons from AA to pp collisions

One of the present challenge for the theoretical understanding of heavy-quark hadronization is represented by the description of the measurements of heavy hadron production in pp, pA and AA collisions from RHIC to top LHC energies. The Λc/D0 ratio observed in AA collisions has a value of the order of the unity, and experimental measurements in pp collisions at both √S = 5.02 TeV and √S = 13 TeV have shown ratios for charm baryons Λc,Ξc0 and Ωc0 respect to D0 meson larger than that measured and expected in e+e−, ep collisions. We present an hadronization mechanism based on the coalescence and fragmentation processes, and the results obtained in AA collisions for D0 and Λc. related baryon to meson ratios at RHIC and LHC. We present moreover results obtained for the charmed hadron production in pp collisions at LHC energies assuming the formation of an hot QCD matter at finite temperature.We calculate the heavy baryon/meson ratio and the pT spectra of charmed hadrons D0. Λc0 and the recently measured Ξc baryon, finding an enhancement in comparison with the ratio observed for e+e−, ep collisions; with this approach we also predict a significant production of Qc.

B-hadron production in NNLO QCD: application to LHC t overline{t} events with leptonic decays

We calculate, for the first time, the NNLO QCD corrections to identified heavy hadron production at hadron colliders. The calculation is based on a flexible numeric framework which allows the calculation of any distribution of a single identified heavy hadron plus jets and non-QCD particles. As a first application we provide NNLO QCD predictions for several differential distributions of B hadrons in t overline{t} events at the LHC. Among others, these predictions are needed for the precise determination of the top quark mass. The extension of our results to other processes, like open or associated B and charm production is straightforward. We also explore the prospects for extracting heavy flavor fragmentation functions from LHC data.

A new parton fragmentation procedure for heavy hadron production in proton–proton collisions

We propose a new procedure for parton-to-hadron fragmentation in proton–proton collisions. The hadronization is considered in the parton-parton center-of-mass (CM) system and hadrons are assumed to be emitted in the direction of outgoing partons in that frame and then their four-momenta are transformed to the overall CM system using relevant Lorentz transformations and appropriate distributions are constructed. For heavy hadron production the energy–momentum condition is imposed. In many cases our procedure disagrees with the commonly used rule that rapidity of produced hadron is the same as rapidity of the parent parton. We illustrate the newly proposed scheme for production of D mesons, Λ c baryon and η c quarkonium in leading-order approach to parton production. The transverse momentum, rapidity and Feynman-x F distributions are shown. We consider c → D and g → D as well as c → η c and g → η c hadronization processes. The resulting x F distributions are much narrower than those obtained in the traditional approach with parton–hadron rapidity equivalence. This has consequences both for mid- and forward rapidities and could have consequences for high-energy neutrino production in the Earth’s atmosphere. We discuss also and fragmentation and find that the second mechanism could be partly responsible for the enhanced production of observed recently by the ALICE collaboration.

NLO QCD corrections to heavy baryon fragmentation functions through quark-diquark model

At very high transverse momenta, the dominant mechanism for heavy hadron production is fragmentation. In this work, we first use the nonrelativistic quark model to compute the heavy baryon fragmentation functions at lowest order of perturbative QCD and then we apply the approximative quark-diquark model for the same fragmentation process. Diquark model enables one to analyze the two-stage fragmentation of a heavy quark into a heavy diquark followed by the fragmentation of produced diquark into outgoing heavy baryon. An acceptable agreement is found between the results obtained through both approaches. Relying on the diquark model, we extend our computation to next-to-leading order accuracy at perturbative QCD.

Gluon fragmentation into triply heavy baryons considering two various scenarios

Heavy hadron production is a powerful implement to study the strong interaction dynamics and the QCD theory. Among all, fragmentation is the dominant production mechanism for heavy baryons with large transverse momentum. This mechanism is described by the fragmentation function (FF) which is the universal and process-independent quantity. In this work we compute, for the first time, the fragmentation density of gluon into triply heavy baryons in two different approaches. In the first approach using the Suzuki's model we calculate the gluon FF in a full perturbative QCD regime and in the second scheme applying the quark-diquark model we reproduce the same FF. Comparison of both models confirms the validity of quark-diquark model which is a convenient model from experimental point of view.

Expansion of massive scalar one-loop integrals to

We report on the results of an ongoing calculation of massive scalar one-loop one-, two-, three- and four-point functions needed in the NNLO calculation of heavy hadron production.

Production ofπ+,K+,K0,K*0,φ,pandΛ0in hadronicZ0decays

We have measured the differential production cross sections as a function of scaled momentum x_p=2p/E_cm of the identified hadron species pi+, K+, K0, K*0, phi, p, Lambda0, and of the corresponding antihadron species in inclusive hadronic Z0 decays, as well as separately for Z0 decays into light (u, d, s), c and b flavors. Clear flavor dependences are observed, consistent with expectations based upon previously measured production and decay properties of heavy hadrons. These results were used to test the QCD predictions of Gribov and Lipatov, the predictions of QCD in the Modified Leading Logarithm Approximation with the ansatz of Local Parton-Hadron Duality, and the predictions of three fragmentation models. Ratios of production of different hadron species were also measured as a function of x_p and were used to study the suppression of strange meson, strange and non-strange baryon, and vector meson production in the jet fragmentation process. The light-flavor results provide improved tests of the above predictions, as they remove the contribution of heavy hadron production and decay from that of the rest of the fragmentation process. In addition we have compared hadron and antihadron production as a function of x_p in light quark (as opposed to antiquark) jets. Differences are observed at high x_p, providing direct evidence that higher-momentum hadrons are more likely to contain a primary quark or antiquark. The differences for pseudoscalar and vector kaons provide new measurements of strangeness suppression for high-x_p fragmentation products.

On searching for heavy hadrons through jet invariant mass in electron-positron annihilation

On the basis of theoretical arguments that heavy hadrons carry almost all of the energy of heavy-quark jets, we investigate a possible recipe to isolate or to concentrate events of heavy-hadron production in electron-positron annihilation.

Quark decay functions and heavy hadron production in QCD

The evolution of outgoing quarks and gluons into outgoing hadrons (the analog of parton decay functions) is studied in QCD perturbation theory. The results are characterized by logarithmic scaling violations and large transverse momenta. The various functions describing the production of hadrons containing a single heavy quark are calculated from first principles.