A method for modelling the prompt production of molecular states using the hadronic rescattering framework of the general-purpose Pythia event generator is introduced. Production cross sections of possible exotic hadronic molecules via hadronic rescattering at the LHC are calculated for the $χ_{c1}(3872)$ resonance, a possible tetraquark state, as well as three possible pentaquark states, $P_c^+(4312)$, $P_c^+(4440)$, and $P_c^+(4457)$. For the $P_c^+$ states, the expected cross section from $Λ_b$ decays is compared to the hadronic-rescattering production. The $χ_{c1}(3872)$ cross section is compared to the fiducial $χ_{c1}(3872)$ cross-section measurement by LHCb and found to contribute at a level of O(1%). Finally, the expected yields of $P_c^+$ production from hadronic rescattering during Run 3 of LHCb are estimated. The prompt background is found to be significantly larger than the prompt $P_c^+$ signal from hadronic rescattering.
A kinematic model based on the superposition of p+p collisions, relativistic geometry and final-state hadronic rescattering is used to predict various hadronic observables in \surd sNN = 2.76 TeV Pb+Pb collisions. Predictions for rapidity and transverse momentum distributions, elliptic flow, and two-boson femtoscopy are presented. A short proper time for hadronization is assumed. Previous calculations using this model which were performed for \surd sNN = 200 GeV Au+Au collisions were shown to describe reasonably well the trends of observables in experiments carried out at that energy, giving t…
In a recent article we presented a model for hadronic rescattering, and some results were shown for pp collisions at LHC energies. In order to extend the studies to pA and AA collisions, the Angantyr model for heavy-ion collisions is taken as the starting point. Both these models are implemented within the general-purpose Monte Carlo event generator Pythia, which makes the matching reasonably straightforward, and allows for detailed studies of the full space--time evolution. The rescattering rate is significantly higher than in pp, especially for central AA collisions, where the typical primar…
We study the effects of hadronic rescattering on hadron distributions in high-energy nuclear collisions by using an integrated dynamical approach. This approach is based on a hybrid model combining (3+1)-dimensional ideal hydrodynamics for the quark gluon plasma (QGP), and a transport model for the hadron resonance gas. Since the hadron distributions are the result of the entire expansion history of the system, understanding the QGP properties requires investigating how rescattering during the hadronic stage affects the final distributions of hadrons. We include multistrange hadrons in our stu…
The $σ$ resonance was observed as a conspicuous $π^+π^-$ peak in hadronic decays like $J/ψ\to π^+π^-ω$ or $D^+\toπ^+π^-π^+$. The phase of the $σ\toπ^+π^-$ amplitude, extracted from production data within the conventional isobar model, is assumed to coincide with that in $ππ$ elastic scattering. We check the validity of this assumption by using Lehmann-Symanzik-Zimmermann (LSZ) reduction and unitarity. The rescattering effects in the final three-particle states are shown to generate a correction to the phase given by a naive application of Watson theorem. We briefly discuss the implications of …
In this article, a framework for hadronic rescattering in the general-purpose Pythia event generator is introduced. The starting point is the recently presented space-time picture of the hadronization process. It is now extended with a tracing of the subsequent motion of the primary hadrons, including both subsequent scattering processes among them and decays of them. The major new component is cross-section parameterizations for a range of possible hadron-hadron combinations, applicable from threshold energies upwards. The production dynamics in these collisions has also been extended to cope…
The hadronic phase in ultrarelativistic nuclear collisions has a large influence on final state observables like multiplicity, flow and $p_t$ spectra, as studied in the UrQMD approach. In this model one assumes that a non-equilibrium decoupling phase follows a fluid dynamical description of the high density phase. Hadrons are produced assuming local thermal equilibrium and dynamically decouple during the hadronic rescattering until the particles are registered in the detectors. This rescattering of hadrons modifies every hadronic bulk observable. The apparent multiplicity of resonances is supp…
We study effects of the hadronic rescattering on final observables especially for multi-strange hadrons such as $ϕ$, $Ξ$ and $Ω$ in high-energy heavy-ion collisions within an integrated dynamical approach. In this approach, (3+1)-dimensional ideal hydrodynamics is combined with a microscopic transport model, JAM. We simulate the collisions with or without hadronic rescatterings and compare observables between these two options so that we quantify the effects of the hadronic rescattering. We find that the mean transverse momentum and the elliptic flow parameter of multi-strange hadrons are less…
Hadronic resonance propagators which take into account the analytical properties of decay processes are built in terms of the dispersion relation technique. Such propagators can describe multi-component systems, for example, those when quark degrees of freedom create a resonance state, and decay products correct the corresponding pole by adding hadronic deuteron-like components. Meson and baryon states are considered, examples of particles with different spins are presented.
We present a first model-independent calculation of $ππ$ intermediate states in the hadronic-light-by-light (HLbL) contribution to the anomalous magnetic moment of the muon $(g-2)_μ$ that goes beyond the scalar QED pion loop. To this end we combine a recently developed dispersive description of the HLbL tensor with a partial-wave expansion and demonstrate that the known scalar-QED result is recovered after partial-wave resummation. Using dispersive fits to high-statistics data for the pion vector form factor, we provide an evaluation of the full pion box, $a_μ^{π\text{-box}}=-15.9(2)\times 10^…
A model for the $B^\pm \to π^-π^+π^\pm$ decay amplitude is proposed to study the large CP violation observed at the high mass region of the Dalitz plane. A short distance $ b \to u $ amplitude with the weak phase $γ$ is considered together with the contribution of a hadronic charm loop and a s-wave $D\bar{D}\to ππ$ rescattering. In the model, the $χ_c^0$ appears as a narrow resonant state of the $D\bar D$ system below threshold. It is introduced in an unitary two channel S-matrix model of the coupled $D\bar D$ and $ππ$ channels, where the $χ_c^0$ complex pole in $D\bar D$ channel shows its sig…
We study the elliptic flow coefficient v_2(eta,b) in Au+Au collisions at sqrt(s)=200 A GeV as a function of pseudorapidity eta and impact parameter b. Using a hybrid approach which combines early ideal fluid dynamical evolution with late hadronic rescattering, we demonstrate strong dissipative effects from the hadronic rescattering stage on the elliptic flow. With Glauber model initial conditions, hadronic dissipation is shown to be sufficient to fully explain the differences between measured v_2 values and ideal hydrodynamic predictions. Initial conditions based on the Color Glass Condensate …
I discuss the effect of final state interactions on the determination of the CKM angle γfrom B -> K + pi decays. Using a simple Regge-based model for rescattering processes, I argue that such effects could be substantial enough to make it problematic to obtain reliable limits on γin this way. Fortunately, an analysis of B -> K + K decays may provide model-independent bounds on rescattering contributions.
A calculation of the hadronic matrix elements for K\toππincluding π-πrescattering effects in a dispersion integral is presented. I study the dependence of the results on the matching scale μand use them to calculate the CP-parameter (ε\prime/ε). I find improved stability on the matching scale and good agreement with the experimental results.
We study phi photoproduction with various hadronic rescattering contributions included, in addition to the Pomeron and pseudoscalar meson-exchange diagrams. We find that the hadronic box diagrams can explain the recent experimental data in the vicinity of the threshold. In particular, the bump-like structure at the photon energy E_gamma \approx 2.3$ GeV is well explained by the K Lambda(1520) rescattering amplitude in the intermediate state, which is the dominant contribution among other hadronic contributions. We also find that the hadronic box diagrams are consistent with the observed spin-d…
Using a relativistic hydrodynamics + hadronic afterburner simulation we explore resonance production in PbPb collisions at 5.02 TeV, and demonstrate that many resonance yields, mean transverse momenta, and flows are very sensitive to the late stage hadronic rescattering. Out of all measured resonances $Λ(1520)$ is affected strongest by the hadronic rescattering stage, which allows to estimate its duration, and even constrain branching ratios of $Σ^* \to Λ(1520)π$ decays. Strong suppression of $Λ(1520)$, which in vacuum has a lifetime of 12.6 fm/$c$, is explained by its small lifetime in a hadr…
Final-state rescattering effects on the hadronic B decays and their impact on direct and mixing-induced CP asymmetries are examined. Implications for some phenomenologies are briefly discussed.
The scattering cross sections of charm mesons with hadrons such as the pion, rho meson, and nucleon are studied in an effective Lagrangian. In heavy ion collisions, rescattering of produced charm mesons by hadrons affects the invariant mass spectra of both charm meson pairs and dileptons resulting from their decays. These effects are estimated for heavy ion collisions at SPS energies and are found to be significant.
There exist many experimental indications that final-state interactions (FSIs) may play a prominent role not only in charmful B decays but also in charmless B ones. We examine the final-state rescattering effects on the hadronic B decay rates and their impact on direct CP violation. The color-suppressed neutral modes such as $B^0\to D^0π^0,π^0π^0,ρ^0π^0,K^0π^0$ can be substantially enhanced by long-distance rescattering effects. The direct CP-violating partial rate asymmetries in charmless B decays to $ππ/πK$ and $ρπ$ are significantly affected by final-state rescattering and their signs are g…
Final-state rescattering effects on the hadronic B decays and their impact on direct CP violation are examined. The phenomenology of the polarization anomaly in $B\toϕK^*$ decays is discussed.
Baryon-strangeness correlation (C$_{BS}$) has been investigated with a multi-phase transport model (AMPT) in $^{197}$Au + $^{197}$Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. The centrality dependence of C$_{BS}$ is presented within the model, from partonic phase to hadronic matter. We find that the system still reserve partial predicted signatures of C$_{BS}$ after parton coalescence. But after hadronic rescattering, the predicted signatures will be obliterated completely. So it seems that both coalescence hadronization process and hadronic rescattering are responsible for the disappearance of…
Production of $ϕ$ mesons is considered in the course of heavy-ion collisions at SPS energies. We investigate the possible difference in momentum distributions of $ϕ$ mesons measured via their leptonic ($μ^+μ^-$) and hadronic ($K^+K^-$) decays. Rescattering of secondary kaons in the dense hadron gas together with the influence of in-medium kaon potential can lead to a relative decrease of a $ϕ$ yield observed in the hadronic channel. We analyze how the in-medium modifications of meson properties affect apparent - reconstructed momentum distributions of $ϕ$ mesons. Quantitative results are prese…
The deuteron binding energy is only 2.2 MeV. At the same time, its yield in Pb+Pb collisions at $\sqrt{s_{NN}} = $2.76 TeV corresponds to a thermal yield at the temperature around 155 MeV, which is too hot to keep deuterons bound. This puzzle is not completely resolved yet. In general, the mechanism of light nuclei production in ultra-high energy heavy ion collisions remains under debate. In a previous work [1] we suggest a microscopic explanation of the deuteron production in central ultra-relativistic Pb+Pb collisions, the main mechanism being $πpn \leftrightarrow πd$ reactions in the hadron…
Initial- and final-state rescattering, neglected in the parton model, have a profound effect in QCD hard-scattering reactions, predicting single-spin asymmetries, diffractive deep inelastic scattering, diffractive hard hadronic reactions, the breakdown of the Lam Tung relation in Drell-Yan reactions, and nuclear shadowing and non-universal antishadowing--leading-twist physics not incorporated in the light-front wavefunctions of the target computed in isolation. I also discuss the use of diffraction to materialize the Fock states of a hadronic projectile and test QCD color transparency, and ano…
The production of the $K^*(892)$ strange resonance in Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV LHC energy is analyzed within the integrated hydrokinetic model (iHKM) at different equations of state of superdense matter. The similar analysis is done also for the RHIC top energy $\sqrt{s_{NN}}=200$ GeV for comparison purposes. A modification of experimental $K^*(892)$-identification is studied for different centralities in view of possible re-scattering of the decay products at the afterburner stage of the fireball evolution. We see quite intensive rescattering of the decay products as well …
In these proceedings we concentrate on the refeeding and rescattering probability of hadronic resonances. We discuss the probability to form resonances in binary baryon-meson or meson-meson collisions as a function of time for various resonances using a transport model approach (UrQMD). We give an estimate of the re-feeding probability using a simplified thermal approach and discuss the relevance for the resonance/non-resonance ratio measured by STAR.
At high energy, exclusive meson photo- and electro-production give access to the structure of hadronic matter. At low momentum transfers, the exchange of a few Regge trajectories leads to a comprehensive account of the cross-sections. Among these trajectories, which are related to the mass spectrum of families of mesons, the Pomeron plays an interesting role as it is related to glue-ball excitations. At high momentum transfers, the exchange of these collective excitations is expected to reduce to the exchange of their simplest (quark or gluon) components. However, contributions from unitarity …
