Final State Interaction Effects Research Articles

Quasielastic hyperon production in -nucleus interactions

We have studied quasielastic charged current hyperon production induced by from a free nucleon and the nucleons bound inside the nucleus. The calculations are performed for several nuclear targets, for example 12C, 40Ar, 56Fe and 208Pb, which are currently being used in various oscillation experiments using accelerator neutrinos. The inputs are the hyperon–nucleon transition form factors determined from neutrino–nucleon scattering as well as from semileptonic decays of neutron and hyperons, using SU(3) symmetry. The calculations for the nuclear targets are done using the local density approximation. The nuclear medium effects due to the Fermi motion and Pauli blocking, and the final state interaction effects due to hyperon–nucleon scattering have been taken into account.

Analysis of B c + → D + K 0* decay

We analyzed the process of Bc+ → D+K0* decay in final-state interaction (FSI) effects as a sizable correction where the intermediate state J/ψDs+ mesons are product via the exchange of D-(D-*). To consider the amplitudes of this intermediate state, we used the quantum chroms dynamic (QCDF) approach. The experimental branching ratio of Bc+ → D+K0* decay is less than 0.2 × 10-6, and our result, which was obtained by using the FSI method, is (0.19 ± 0.08) × 10-6, which is near the experimental result.

Improving the accuracy of neutrino energy reconstruction in charged-current quasielastic scattering off nuclear targets

We report the results of a theoretical study of quasielastic electron and neutrino interactions with carbon. Our approach takes into account the effects of final-state interactions between the struck nucleon and the residual nucleus, neglected in the impulse approximation, through a generalization of the spectral function formalism. The calculated electron-scattering cross sections turn out to be in very good agreement with the available data over a broad kinematical region. The impact of nuclear effects on the reconstruction of neutrino energy in charged-current quasielastic processes is also studied, and the results of our approach are compared to the predictions of the relativistic Fermi gas model, routinely employed in most Monte Carlo simulations. Finally, we discuss the limitations of the existing procedure for energy reconstruction and propose a new, improved, one. At energy ~600 MeV, we observe a sizable difference between neutrino and antineutrino scattering, important for the measurements of charge-parity symmetry violation. Our analysis suggests that a reliable determination of neutrino energy can only be obtained from models validated by a systematic comparison to the available electron-scattering data.

Study of kaon decay to two pions

The weak decay of the kaon to two pions is studied within the model of Nambu and Jona-Lasinio. Using the standard effective weak Hamiltonian, both the decay amplitude arising from an intermediate state $\ensuremath{\sigma}$ meson and the direct decay amplitude are calculated. The effect of final state interactions is also included. When the matching scale is chosen such that the decay amplitude with isospin $I=2$ is close to its experimental value, our model including the $\ensuremath{\sigma}$ meson contributes up to 80% of the total $I=0$ amplitude. This supports recent suggestions that the $\ensuremath{\sigma}$ meson should play a vital role in explaining the $\mathrm{\ensuremath{\Delta}}I=1/2$ rule in this system.

A Light-Front Approach to the 3He Spectral Function

The analysis of semi-inclusive deep inelastic electron scattering off polarized 3He at finite momentum transfers, aimed at the extraction of the quark transverse-momentum distributions in the neutron, requires the use of a distorted spin-dependent spectral function for 3He, which takes care of the final state interaction effects. This quantity is introduced in the non-relativistic case, and its generalization in a Poincaré covariant framework, in plane wave impulse approximation for the moment being, is outlined. Studying the light-front spin-dependent spectral function for a J = 1/2 system, such as the nucleon, it is found that, within the light-front dynamics with a fixed number of constituents and in the valence approximation, only three of the six leading twist T-even transverse-momentum distributions are independent.

Final state interaction effects in B 0 → J/ψπ 0 decay

In this research the exclusive decay of B 0 → J/ψπ 0 is calculated by QCD factorization (QCDF) method and final-state interaction (FSI). First, the B 0 → J/ψπ 0 decay is calculated via QCDF method. The result that is found by using the QCDF method is less than the experimental result. So FSI is considered to solve the B 0 → J/ψπ 0 decay. For this decay, the D + D −* and D 0 $\bar D^{0*} $ via the exchange of D −, D −* and $\bar D^0 $ , $\bar D^{0*} $ mesons are chosen for the intermediate states. The above intermediate states are calculated by using the QCDF method. The experimental branching ratio of B 0 → J/ψπ 0 decay is (1.76 ± 0.16) × 10−5 and our results calculated by QCDF and FSI are (0.56 ± 0.11) × 10−5 and (1.3 ± 0.09) × 10−5, respectively.

Final state interaction effect in pure annihilation Bs → ρρ decay

We analyzed the process of decay in quantum chromodynamics factorization (QCDF) and final state interaction (FSI) effects. In QCDF, for this decay, we have only the annihilation graph and we expected a small branching ratio. Then we considered the FSI effect as a sizable correction where the intermediate states are , , , and mesons. To consider the amplitudes of these intermediate states, the QCDF approach was used. The experimental branching ratio of is less than and our result is and from QCDF and FSI, respectively.

Final state interaction effects in B+→Ds*+ ϕ decay

In this article the exclusive decay of [Formula: see text] is calculated using the QCD factorization (QCDF) method and final state interaction (FSI). First, the [Formula: see text] decay is calculated via the QCDF method and only the annihilation graphs exist in that method. The result found using the QCDF method is lower than the experimental result. FSI is considered to solve the [Formula: see text] decay. For this decay, D+K0, D0K+, and [Formula: see text] via the exchange of K0, K+, and [Formula: see text] are chosen for the intermediate states and we calculate B+ → D+K0 → [Formula: see text] decay. The amplitude of B+ → D+K0 decay is calculated using the QCDF method again. The experimental branching ratio of [Formula: see text] decay is less than 1.2 × 10−5 and our results calculated using the QCDF method and FSI are (0.4 ± 0.06) × 10−7 and (0.93 ± 0.08) × 10−5, respectively.

Final state interaction effects in the B + → D + K 0 decay

The exclusive decay of B + → D + K 0 is calculated by the QCD factorization method (QCDF) and final state interaction (FSI). First, the B + → D + K 0 decay is calculated via QCDF method. The result that is found by using the QCDF method is less than the experimental result. So FSI is considered to solve the B + → D + K 0 decay. For this decay, the D s + π0, D s + *ρ0, D s + *ϕ via the exchange of \(\bar K^0\), \(\bar K^{0*} \), D −, and D −* mesons are chosen for the intermediate states. The above intermediate states are calculated by using the QCDF method. In the FSI effects, the results of our calculations depend on η as the phenomenological parameter. The range of this parameter is selected from 2 to 2.4. It is found that if η = 2.4 is selected, the numbers of the branching ratio are placed in the experimental range. The experimental branching ratio of this decay is less than 2.9 × 10−6 and our results calculated by QCDF and FSI are (0.16 ± 0.04) × 10−6 and (2.8 ± 0.09) × 10−6, respectively.

Final-state interactions in deep-inelastic scattering from a tensor polarized deuteron target

Deep-inelastic scattering (DIS) from a tensor polarized deuteron is sensitive to possible non-nucleonic components of the deuteron wave function. To accurately estimate the size of the nucleonic contribution, final-state interactions (FSIs) need to be accounted for in calculations. We outline a model that, based on the diffractive nature of the effective hadron-nucleon interaction, uses the generalized eikonal approximation to model the FSIs in the resonance region, taking into account the proton-neutron component of the deuteron. The calculation uses a factorized model with a basis of three resonances with mass W < 2 GeV as the relevant set of effective hadron states entering the final-state interaction amplitude for inclusive DIS. We present results for the tensor asymmetry observable Azz for kinematics accessible in experiments at Jefferson Lab and Hermes. For inclusive DIS, sizeable effects are found when including FSIs for Bjorken x > 0.2, but the overall size of Azz remains small. For tagged spectator DIS, FSIs effects are largest at spectator momenta around 300 MeV and for forward spectator angles.

Particle production and final state effects in nuclear collisions

We discuss various features of multi-particle production in high-energy nuclear collisions within the IP-Glasma model. We demonstrate that for some observables in heavy- ion collisions the effects of final state interactions governed by fluid-dynamics are essential. In smaller systems, like proton-lead collisions, the same model fails to describe the azimuthal anisotropy of produced particles. This failure can be due to neglected initial state correlations or the lack of a detailed description of the fluctuating spatial structure of the proton at high energies, or both.

Nucleon pole contribution in thepp→ppK+K−reaction below theϕmeson threshold

Nucleon pole contribution in the $pp\ensuremath{\rightarrow}pp{K}^{+}{K}^{\ensuremath{-}}$ reaction below the threshold of the production of the $\ensuremath{\phi}$ meson is studied within the effective Lagrangian approach. It is assumed that the ${K}^{\ensuremath{-}}p$ final state originates from the decay of the hyperons $\ensuremath{\Lambda}(1115)$ and $\ensuremath{\Lambda}(1405)$. In addition to the $pp$ final state interaction (FSI) parametrized using the Jost function, we have also considered the ${K}^{+}{K}^{\ensuremath{-}}$ FSI with the techniques of the chiral unitary approach, where the scalar mesons ${f}_{0}(980)$ and ${a}_{0}(980)$ were dynamically generated. Hence, the contributions from scalar mesons ${f}_{0}(980)$ and ${a}_{0}(980)$ occur through the ${K}^{+}{K}^{\ensuremath{-}}$ FSI. It is shown that the available experimental data are well reproduced, especially the total cross sections and the invariant mass distributions of $pp$ and ${K}^{+}{K}^{\ensuremath{-}}$. Furthermore, different forms of the couplings (pseudoscalar and pseudovector) for the $\ensuremath{\pi}NN$ interaction and different strengths for the proton-proton FSI are also investigated. It is found that the contributions from hyperons $\ensuremath{\Lambda}(1115)$ and $\ensuremath{\Lambda}(1405)$ are different between these two kinds of couplings. On the other hand, the effects of the proton-proton FSI can be adjusted by the cutoff parameters used in the form factors.

Final State Interaction Effects in B0 → D0*D0 Decay

The exclusive decay of B0 →&nbsp;D0* ¯&nbsp;D0&nbsp;is calculated by the QCD factorization (QCDF) method and a method involving the final state interaction (FSI). The result obtained by the QCDF method was less than the experimental value, which indicates the necessity to consider FSI. For the decay, the D+D−*,&nbsp;K+*K−,&nbsp;p+п−,&nbsp;p0п0,&nbsp;D−*s&nbsp;D+s, and&nbsp;J/wп0 via the exchange of п−(p−),&nbsp;D−s&nbsp;(D−*s&nbsp;),&nbsp;D−(D−*), ¯&nbsp;D0( ¯&nbsp;D0*), and K−(K−*)&nbsp;mesons are chosen as intermediate states, which were calculated by the QCDF method. As for the FSI effects, the results of our calculations depend on&nbsp;n as the phenomenological parameter. The range of this parameter is selected to be from 0.8 to 1.6. If&nbsp;n = 1.4 is selected, the theoretical result fits the experimental branching ratio of the B0 →&nbsp;D0* ¯&nbsp;D0 decay that is less than 2.9 × 10^−4. Our results calculated by the QCDF and FSI methods are (0.13±0.11)×10^−4 and (2.2±0.08)×10^−4, respectively.

Chiral nonet mixing inη′→ηππdecay

Underlying mixing of scalar mesons is studied in $\eta'\rightarrow \eta\pi\pi$ decay within a generalized linear sigma model of low-energy QCD which contains two nonets of scalar mesons and two nonets of pseudoscalar mesons (a quark-antiquark nonet and a four quark nonet). The model has been previously employed in various investigations of the underlying mixings among scalar mesons below and above 1 GeV (as well as those of their pseudoscalar chiral partners) and has provided a coherent global picture for the physical properties and quark substructure of these states. It is found that the linear sigma model with only a single lowest-lying nonet is not accurate in predicting the decay width, but inclusion of the mixing of this nonet with the next-to-lowest lying nonet, together with the effect of final state interaction of pions, significantly improves this prediction and agrees with experiment up to about 1\%. It is also shown that while the prediction of the leading order of the generalized model for the Dalitz parameters is not close to the experiment, the model is able to give a reasonable prediction of the energy dependencies of the normalized decay amplitude squared and that this is expected to improve with further refinement of the complicated underlying mixings. Overall this investigation provides further support for the global picture of scalar mesons: those below 1 GeV are predominantly four-quark states and significantly mix with those above 1 GeV which are closer to the conventional p-wave quark-antiquark states.

Anomalous population ofHe10states in reactions withLi11

Structure with the lowest energy observed in the $^{10}$He spectrum populated in the proton knockout reaction with $^{11}$Li beam has a peak at $1.2-1.5$ MeV. This peak is usually interpreted as a resonant $0^+$ ground state of $^{10}$He. Our theoretical calculations indicate that this peak is likely to be a pileup of $1^-$, $0^+$, and $2^+$ excitations with very similar shapes. %We predict a very specific nature of the $1^-$ excitation in $^{10}$He. Moreover, the ``soft'' $1^-$ excitation appears to be the lowest one in energy. Such an anomalous continuum response is traced to the halo structure of $^{11}$Li providing extreme low energy shift to all the expected continuum excitations. Competitions of the initial state structure (ISS) and the final state interaction (FSI) effects on the spectrum and three-body correlations in $^{10}$He are discussed. Analogous effect of the extreme low-energy shift could also be expected in other cases of $2n$ emitters populated in reactions with halo nuclei. Simplified example of the $^{10}$He spectrum in $\alpha$ knockout from $^{14}$Be, is given. We also discuss limits on the properties of $^{9}$He stemming from the observed $^{10}$He spectrum.

Effects of final state interactions in $$B^ + \to D_S^ + \bar K^0$$ decay

We investigate the effects of final state interactions (FSI) contributions in the nonleptonic two body \(B^ + \to D_S^ + \bar K^0\) decay, however the hadronic decay of \(B^ + \to D_S^ + \bar K^0\) is analyzed by using “QCD factorization” (QCDF) method and final state interaction (FSI). First, the \(B^ + \to D_S^ + \bar K^0\) decay is calculated via QCDF method and only the annihilation graphs exist in that method. Hence, the FSI must be seriously considered to solve the \(B^ + \to D_S^ + \bar K^0\) decay and the D0π+(D0*ρ+), D+π0(D+*ρ0) and D+ηc(D+*J/ψ) via the exchange of K+(*), K0(*) and Ds+(*) mesones are chosen for the intermediate states. To estimate the intermediate states amplitudes, the QCDF method is again used. These amplitudes are used in the absorptive part of the diagrams. The experimental branching ratio of \(B^ + \to D_S^ + \bar K^0\) decay is less than 8 × 10−4 and the predicted branching ratio is 0.23 × 10−9 in the absence of FSI effects and it becomes 6.74 × 10−4 when FSI contributions are taken into account.

Effects of final-state interactions in pure annihilation decay of B s 0 → π+π −

The hadronic decay of Bs0 → π+π− is analyzed by using “QCD factorization” (QCDF) method and final-state interaction (FSI). First, the Bs0 → π+π− decay is calculated via QCDF method and the annihilation graphs only exist in this method. Hence, the FSI must be seriously considered to solve the Bs0 → π+π− decay and the K+(*)K−(*) and \(K^{0(*)} K^{\bar 0(*)}\) via the exchange of K0(*) and K−(*) mesons are chosen for the intermediate states. To estimate the intermediate state amplitudes, the QCDF method is again used. These amplitudes are used in the absorptive part of the diagrams. The experimental branching ratio of Bs0 → π+π− decay is less than 1.2 × 10−6 and our results according to the QCDF method and FSI are 0.68 × 10−8 and 1.18 × 10−6, respectively.

Hydrodynamic approach to p–Pb

The formation and collective expansion of the fireball formed in ultrarelativistic p-A and d-A collisions is discussed. Predictions of the hydrodynamic model are compared to recent experimental results. The presence of strong final state interaction effects in the small dense systems is consistent with the observed azimuthal anisotropy of the flow and with the mass dependence of the average transverse momentum and of the elliptic flow. This raises the question of the mechanism explaining such a rapid build up of the collective flow and the large degree of local equilibration needed to justify this scenario.

Final-state interaction effects in neutral-current neutrino and antineutrino cross sections at MiniBooNE kinematics

The analysis of the recent neutral-current elastic neutrino and antineutrino-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 investigate the sensitivity to final-state interactions and compare the MiniBooNE data with the results obtained in the relativistic Green's function model with different parameterizations for the phenomenological relativistic optical potential.

Final State Interaction Effects in B0→J/ψπ0Decay

Final State Interaction Effects in B0→J/ψπ0Decay