Role Of Final State Interactions Research Articles

Electron Scattering on 4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^4$$\\end{document}He from Coupled-Cluster Theory

We present a coupled-cluster calculation for the electron-4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^4$$\\end{document}He scattering in the region of the quasi-elastic peak. We show the longitudinal and transverse responses separately, and discuss results within two distinct theoretical methods: the Lorentz integral transform and spectral functions. The comparison between them allows to investigate the role of final state interactions, two-body currents and relativistic effects.

The role of final-state interaction in tensor polarization effects of the reaction gamma d rightarrow p n pi ^{0}

Tensor analyzing-power components T_{20}, T_{21}, and T_{22} for the reaction gamma drightarrow nppi ^0 have been studied for the first time in the photon energy range from 280 to 500 MeV. The data are extracted from the experimental statistics accumulated at the VEPP-3 storage ring in 2002–2003. The measured asymmetries are compared with the results of statistical simulations performed with the gamma drightarrow nppi ^0 amplitude from a spectator model, taking into account corrections for the final-state interaction. The comparison demonstrates quite good agreement between the experimental results and the theory.

On the photoproduction reactions $$\varvec{\gamma d\rightarrow \pi NN}$$

A review of our works providing a theoretical description of incoherent pion photoproduction on the deuteron is presented. The existing $\gamma d\to\pi NN$ data are analysed, especially those obtained more recently by the CLAS Collaboration at JLab, the A2 Collaboration at MAMI at Mainz, and the PION@MAX-lab Collaboration at Lund. A procedure, which accounts for the final state interactions (FSI), is applied to extract $\gamma n\to\pi N$ differential cross sections from the deuteron data. The role of FSI is discussed. We also comment on the results of other works in connection with some discrepancies seen in comparing the model with experiment. The electromagnetic properties of baryon $N^\ast$ resonances, improved using the extracted $\gamma n\to\pi N$ differential cross sections, are presented. A model description of the cross section data from charged-pion photoproduction reactions $\gamma d\to\pi^{\pm}NN$ near threshold is also given. The $\gamma d\to\pi^-pp$ data are used to extract the $E_{0+}$ multipole and total crsoss sections of the reaction $\gamma n\to\pi^-p$ near threshold.

Hadron production in elementary nucleon–nucleon reactions from low to ultra-relativistic energies

We study the hadron production in $$p+p$$ , $$p+n$$ and $$n+n$$ reactions within the microscopic Parton–Hadron-Dynamics (PHSD) transport approach in comparison to PYTHIA 8.2. We discuss the details of the “PHSD tune” of the Lund string model (realized by event generators FRITIOF and PYTHIA) in the vacuum (as in $$N+N$$ collisions) as well as its in-medium modifications relevant for heavy-ion collisions where a hot and dense matter is produced. We compare the results of PHSD and PYTHIA 8.2 (default version) for the excitation function of hadron multiplicities as well as differential rapidity y, transverse momentum $$p_T$$ and $$x_F$$ distributions in $$p+p$$ , $$p+n$$ and $$n+n$$ reactions with the existing experimental data in the energy range $$\sqrt{s_{NN}} = 2.7 - 7000$$ GeV. We discuss the production mechanisms of hadrons and the role of final state interactions (FSI) due to the hadronic rescattering. We also show the influence of the possible quark–gluon plasma (QGP) formation on hadronic observables in $$p+p$$ collisions at LHC energies. We stress the importance of developing a reliable event generator for elementary reactions from low to ultra-relativistic energies in view of actual and upcoming heavy-ion experiments.

Charged pion production inνμinteractions on hydrocarbon at⟨Eν⟩=4.0 GeV

Charged pion production via charged current $\nu_{\mu}$ interactions on plastic (CH) is studied using the MINERvA detector exposed to the NuMI wideband neutrino beam at Fermilab. Events with hadronic invariant mass W $<$ 1.4 GeV are selected to isolate single pion production, which is expected to occur primarily through the $\Delta(1232)$ resonance. Cross sections as functions of pion production angle and kinetic energy are reported and compared to predictions from different theoretical calculations and generator-based models, for neutrinos ranging in energy from 1.5 GeV to 10 GeV. The data are best described by calculations which include significant contributions from pion intranuclear rescattering. These measurements constrain the primary interaction rate and the role of final state interactions in pion production, both of which need to be well understood by neutrino oscillation experiments.

Three-body model for the analysis of quasifree scattering reactions in inverse kinematics

A new method to calculate cross sections for $(p,pn)$ and $(p,2p)$ reactions measured under inverse kinematics conditions is proposed. The method uses the prior form of the scattering transition amplitude and replaces the exact three-body wave function appearing in this expression with an expansion in terms of $p\ensuremath{-}n$ or $p\ensuremath{-}p$ states, covering the physically relevant excitation energies and partial waves. A procedure of discretization, similar to that used in continuum-discretized coupled-channels calculations, is applied to make this expansion finite and numerically tractable. The proposed formalism is nonrelativistic, but several relativistic kinematical corrections are applied to extend its applicability to energies of current interest. The underlying optical potentials for the entrance and exit channels are generated microscopically by folding an effective density-dependent $G$ matrix with the density of the composite nucleus. Numerical calculations for $^{12}\mathrm{C}$($p,2p$), $^{12}\mathrm{C}$($p,pn$), and $^{23}\mathrm{O}$($p,pn$) at $\ensuremath{\sim}400$ MeV/nucleon are presented to illustrate the method. The role of final-state interactions and Pauli principle between the outgoing nucleons is also discussed.

Role of pion exchange inηmeson photoproduction on the deuteron

Incoherent $\eta$ photoproduction on the deuteron is studied with the main emphasis on the role of final state interactions. In addition to the previously studied mechanisms of $NN$ and $\eta N$ rescatterings, the role of an intermediate pion exchange is considered in detail, where first a pion is photoproduced on one nucleon and then rescatters into an $\eta$ meson on the other, the spectator nucleon. It is found, that the role of this pion mediated contribution is comparable in size to that of $\eta N$ rescattering. Results for total and semi-inclusive differential cross sections and associated polarization observables are presented. In particular polarization observables show a significant sensititvity to final state interactions.

On the role of final-state interactions in Dalitz plot studies

The study of Dalitz plots of heavy-meson decays to multi-hadron final states has received intensified interest by the possibility to gain access to precision investigations of CP violation. A thorough understanding of the hadronic final-state interactions is a prerequisite to achieve a highly sensitive, model-independent study of such Dalitz plots. We illustrate some of the theoretical tools, predominantly taken from dispersion theory, available for these and related purposes, and discuss the low-energy decays omega, phi --> 3pi in some more detail.

Final State Interaction Effects on theB+→J/ψρ+Decay

The exclusive decay ofB+→J/ψρ+is studied in the framework of the QCD factorization (QCDF) method and final state interaction (FSI). A directB+→J/ψρ+decay is only occurred via a tree and a penguin based on the quark diagram analysis. The result that is found by using the QCDF method is less than the experimental result, so, the role of FSI is considered. The intermediate statesD+D̅0,D+*D̅0*,D+*D̅0, andD+D̅0*via the exchange ofD-andD-*are contributed to theB+→J/ψρ+decay. The above intermediate states is 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 are selected from 1 to 2. For the exchanged particlesD-andD-*, it is found that ifη=1.58~1.83is selected the numbers of the branching ratio are placed in the experimental range. The experimental branching ratio ofB+→J/ψρ+decay is(5±0.8)×10-5, and our prediction number is(1.42±0.36)×10-5in the absence of FSI effects, and it becomes(4.2~5.8)×10-5when FSI contributions are taken into account.

Relativistic descriptions of final-state interactions in neutral-current neutrino-nucleus scattering at MiniBooNE kinematics

The analysis of the recent neutral-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 cross sections with the relativistic distorted-wave impulse-approximation and with the relativistic Green's function model to investigate the sensitivity to final state interactions. The role of the strange-quark content of the nucleon form factors is also discussed.

The BLAST experiment

The Bates large acceptance spectrometer toroid (BLAST) experiment was operated at the MIT-Bates Linear Accelerator Center from 2003 until 2005. The detector and experimental program were designed to study, in a systematic manner, the spin-dependent electromagnetic interaction in few-nucleon systems. As such the data will provide improved measurements for neutron, proton, and deuteron form factors. The data will also allow details of the reaction mechanism, such as the role of final state interactions, pion production, and resonances to be studied. The experiment used: a longitudinally polarized electron beam stored in the South Hall Storage Ring; a highly polarized, isotopically pure, internal gas target of hydrogen or deuterium provided by an atomic beam source; and a symmetric, general purpose detector based on a toroidal spectrometer with tracking, time-of-flight, Cherenkov, and neutron detectors. Details of the experiment and operation are presented.

On the role of FSI in K → 2π decay

Contrary to widespread opinion that the final-state interaction (FSI) enlarges the amplitude 〈2π; I = 0|K0〉, we argue that FSI is not able to increase the absolute value of this amplitude.

Baryon-baryon and baryon-antibaryon interaction amplitudes in the spin-momentum operator expansion method

Partial-wave scattering amplitudes in baryon-baryon and baryon-antibaryon collisions and amplitudes for the production and decay of baryon resonances are constructed in the framework of the spin-momentum operator expansion method. The approach is relativistically invariant and it allows us to perform combined analyses of different reactions imposing analyticity and unitarity directly. The role of final-state interactions (triangle and box diagrams) is discussed.

Final state interactions and hadron quenching in cold nuclear matter

I examine the role of final state interactions in cold nuclear matter in modifying hadron production on nuclear targets with leptonic or hadronic beams. I demonstrate the extent to which available experimental data in electron-nucleus collisions can give direct information on final state effects in hadron-nucleus and nucleus-nucleus collisions. For hadron-nucleus collisions, a theoretical estimate based on a parton energy loss model tested in lepton-nucleus collisions shows a large effect on midrapidity hadrons at fixed target experiments. At energies currently available at the BNL Relativistic Heavy Ion Collider, the effect is large for negative rapidity hadrons but mild at midrapidity. This final state cold hadron quenching needs to be taken into account in jet tomographic analysis of the medium created in nucleus-nucleus collisions.

Slow proton production in semi-inclusive DIS off nuclei: the role of final state interaction

The effects of the final state interaction on the production of slow protons in semi-inclusive deep-inelastic lepton scattering off nuclei is considered within the spectator mechanism and a realistic approach in which the rescattering in the medium of both the recoiling proton and the hadronizing nucleon debris are taken into account.

Final state interactions in decays of the exoticπ1meson

We analyze the role of final state interactions (FSI) in decay of the lightest exotic meson, with ${J}^{PC}={1}^{\ensuremath{-}+}{\ensuremath{\pi}}_{1}$. We use the relativistic Lippmann-Schwinger equation for two coupled $\ensuremath{\pi}{b}_{1}$ and $\ensuremath{\pi}\ensuremath{\rho}$ channels. The first one is the predicted dominant decay mode of the ${\ensuremath{\pi}}_{1}$, whereas in the other a narrow ${\ensuremath{\pi}}_{1}(1600)$ exotic signal has been reported by the E852 collaboration. The FSI potential is constructed, based on the $\ensuremath{\omega}$ meson exchange between the two channels. We find that this process introduces corrections to the ${\ensuremath{\pi}}_{1}$ widths of the order of only a few MeV. Therefore, we conclude that a substantial $\ensuremath{\pi}\ensuremath{\rho}$ mode cannot be generated through level mixing.

Final state interaction in the reactionNN→ηNN

The production of $\eta$ mesons in $NN$ collisions in the near threshold region is analyzed with special emphasis on the role of final state interaction which is calculated using three-body scattering theory. The three-body aspects are shown to be very important in interpreting experimental results for the total cross section of $pp\to\eta pp$. Furthermore, energy spectra and angular distributions of the emitted particles are calculated and compared to experimental data.

Spacelike and timelike response of confined relativistic particles

Basic theoretical issues relating to the response of confined relativistic particles are considered including the scaling of the response in spacelike and timelike regions of momentum transfer and the role of final state interactions. A simple single particle potential model incorporating relativity and linear confinement is solved exactly and its response is calculated. The response is studied in common approximation schemes and it is found that final state interactions effects persist in the limit that the three-momentum transferred to the target is large. The fact that the particles are bound leads to a non-zero response in the timelike region of four-momentum transfer equal to about 10% of the total strength. The strength in the timelike region must be taken into account to fulfill the particle number sum rule.

Chiral Dynamics with Strange Quarks: Mysteries and Opportunities

Recent developments and open issues in chiral dynamics with strange quarks are reviewed. Topics include: Order parameters of chiral symmetry breaking, the flavor dependence of these order parameters, speculations about the phase structure of QCD with varying number of flavors, OZI violation and its natural emergence in case of a small strange quark condensate, heavy kaon chiral perturbation theory, an update on pion-pion, pion-kaon and pion-nucleon sigma terms, the dynamics and nature of scalar mesons, the role of the scalar pion and kaon form factors, attempts to describe some strange baryons employing coupled channel dynamics tied to unitarity and chiral perturbation theory, and the role of final state interactions in Goldstone boson pair production in proton-proton collisions.

Effects of the final state interaction in the electrodisintegration of the deuteron at intermediate and high energies

The role of final state interactions (FSIs) in the inclusive quasielastic disintegration of the deuteron is investigated treating the two-nucleon final state within the exact continuum solutions of the nonrelativistic Schr\"odinger equation, as well as within the Glauber multiple-scattering approach. It is shown that for values of the Bjorken scaling variable ${x}_{\mathrm{Bj}}\ensuremath{\simeq}1$ both approaches provide similar results, except for the case ${x}_{\mathrm{Bj}}\ensuremath{\gtrsim}1,$ where they appreciably disagree. It is demonstrated that present experimental data, which are mostly limited to a region of four-momentum transfer $[{Q}^{2}\ensuremath{\lesssim}4 (\mathrm{GeV}{/c)}^{2}]$ where the center-of-mass energy of the final state is below the pion threshold production, can be satisfactorily reproduced by an approach based on an exact solution of the Schr\"odinger equation and not by the Glauber approach.