Final State Interactions Research Articles

First combined tuning on transverse kinematic imbalance data with and without pion production constraints

We present the first combined tuning, using , of four transverse kinematic imbalance measurements of neutrino-hydrocarbon scattering, both with and without pion final states, from the T2K and MINERvA experiments. As a proof of concept, we have simultaneously tuned the initial state and final-state interaction models (SF-CFG and hA, respectively), producing a new effective model that more accurately describes the data. Published by the American Physical Society 2024

Benchmarking the non-flow contributions to the elliptic flow parameter (v 2) in proton-proton collisions

Abstract This manuscript reports on the elliptic flow parameter, $v_{_2}$, in proton-proton (p-p) collisions using PYTHIA8 event generator simulations. The typical Event Plane ($EP$) method $v_{_2}$($EP$) as the one used for the real data analysis has been adopted to measure the $v_{_2}$ of particles composed of different quark flavors, and produced at mid-pseudorapidity $|\eta| \le 1$ at center-of-mass energy $\sqrt{s}$ = 200 GeV and $\sqrt{s}$ = 13 TeV. The event plane has been constructed using the soft charged particles with transverse momentum ($p{_{_T}} < $ 2 GeV/c) produced in various $\eta$ ranges. The pseudorapidity gap technique ($\Delta\eta$) between the particle of interest and the soft charged particles contributed to the event plane constructions has been utilized to benchmark the non-flow contributions. The $v_{_2}^{\pi^{^\pm,}\pi^{^0}}$, $v_{_2}^{J/\psi,\Upsilon, K, D, B}$, and the $v_{_2}^{\gamma_{dir}}$ show similar pattern dependence on the transverse momentum for the same $\Delta\eta$, at both $\sqrt{s}$ = 200 GeV and $\sqrt{s}$ = 13 TeV. At each center-of-mass energy, the measured $v_{_2}$ shows obvious dependence on the quark flavor contents where $v_{_2}^{\gamma_{dir}}$ $\le$ $v_{_2}^{J/\psi, \Upsilon, K, D, B}$ $\le$ $v_{_2}^{\pi^{^\pm,}\pi^{^0}}$ for similar $\Delta\eta$ gap. The measured $v_{_2}$ shows slightly higher values at smaller $\sqrt{s}$ for particles of similar values of $\Delta\eta$ gaps, particularly at small $\Delta\eta$ gap. The measured $v_{_2}$ for all particles shows systematic decreases with increasing the $\Delta\eta$ gap as expected from the previous experimental results. Because PYTHIA8 simulations do not incorporate final state interactions, the $v_{_2}(EP)$ values reported here primarily reflect the non-flow contributions and its dependence on the quark contents, pseudorapidity gap as a function on $p_{T}$ at each center of mass-energy. These contributions should be carefully subtracted from the signal in real data analysis that employs the same event plane determination algorithm.

[formula omitted] and [formula omitted] two-particle femtoscopic correlations in PbPb collisions at [formula omitted]

Two-particle correlations are presented for KS0, ▪, and ▪ strange hadrons as a function of relative momentum in lead-lead collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The dataset corresponds to an integrated luminosity of 0.607nb−1 and was collected using the CMS detector at the CERN LHC. These correlations are sensitive to quantum statistics and to final-state interactions between the particles. The source size extracted from the KS0KS0 correlations is found to decrease from 4.6 to 1.6fm in going from central to peripheral collisions. Strong interaction scattering parameters (i.e., scattering length and effective range) are determined from the ▪ and ▪ (including their charge conjugates) correlations using the Lednický–Lyuboshitz model and are compared to theoretical and other experimental results.

Branching ratios and CP asymmetries of the quasi-two-body decays Bc→K0∗(1430,1950)D(s)→KπD(s)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_c \\rightarrow \\ K^{*}_0(1430,1950) D_{(s)} \\rightarrow K \\pi D_{(s)} $$\\end{document} in the PQCD approach

In this paper, we investigate the quasi-two-body decays Bc→K0∗(1430,1950)D(s)→KπD(s)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_c \\rightarrow K_0^{*}(1430,1950) D_{(s)} \\rightarrow K \\pi D_{(s)}$$\\end{document} within the perturbative QCD (PQCD) framework. The S-wave two-meson distribution amplitudes (DAs) are introduced to describe the final state interactions of the Kπ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K\\pi $$\\end{document} pair, which involve the time-like form factors and the Gegenbauer polynomials. In the calculations, we adopt two kinds of parameterization schemes to describe the time-like form factors: one is the relativistic Breit–Wigner (RBW) formula, which is usually more suitable for the narrow resonances, and the other is the LASS line shape proposed by the LASS Collaboration, which includes both the resonant and nonresonant components. We find that the branching ratios and the direct CP violations for the decays Bc→K0∗(1430)D(s)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_c \\rightarrow K_0^{*}(1430) D_{(s)}$$\\end{document} obtained from those of the quasi-two-body decays Bc→K0∗(1430)D(s)→KπD(s)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_c \\rightarrow K_0^{*}(1430) D_{(s)} \\rightarrow K \\pi D_{(s)}$$\\end{document} under the narrow width approximation (NWA) can be consistent well with the previous PQCD results calculated in the two-body framework by assuming that K0∗(1430)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K^*_0(1430)$$\\end{document} is the lowest lying q¯s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\bar{q} s$$\\end{document} state, which is the so-called scenario II (SII). We conclude that the LASS parameterization is more suitable to describe the K0∗(1430)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K_0^{*}(1430)$$\\end{document} than the RBW formula, and the nonresonant components play an important role in the branching ratios of the decays Bc→K0∗(1430)D(s)→KπD(s)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_c \\rightarrow K_0^{*}(1430) D_{(s)} \\rightarrow K \\pi D_{(s)}$$\\end{document}. In view of the large difference between the decay width measurements for the K0∗(1950)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K_0^{*}(1950)$$\\end{document} given by BaBar and LASS collaborations, we calculate the branching ratios and the CP violations for the quasi-two-body decays Bc→K0∗(1950)D(s)→KπD(s)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_c \\rightarrow K_0^{*}(1950) D_{(s)} \\rightarrow K \\pi D_{(s)}$$\\end{document} by using two values, ΓK0∗(1950)=0.100±0.04\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Gamma _{K^*_0(1950)}=0.100\\pm 0.04$$\\end{document} GeV and ΓK0∗(1950)=0.201±0.034\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Gamma _{K^*_0(1950)}=0.201\\pm 0.034$$\\end{document} GeV, besides the two kinds of parameterizations for the resonance K0∗(1950)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K^*_0(1950)$$\\end{document}. We find that the branching ratios and the direct CP violations for the decays Bc→K0∗(1950)D(s)→KπD(s)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_c \\rightarrow K_0^{*}(1950) D_{(s)} \\rightarrow K \\pi D_{(s)}$$\\end{document} have not as large difference between the two parameterizations as the case of decays involving the K0∗(1430)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K^*_0(1430)$$\\end{document}, especially for the results with ΓK0∗(1950)=0.201±0.034\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Gamma _{K^*_0(1950)}=0.201\\pm 0.034$$\\end{document} GeV. The effect of the nonresonant component in the K0∗(1950)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K^*_0(1950)$$\\end{document} may be not so serious as that in the K0∗(1430)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K^*_0(1430)$$\\end{document}. The quasi-two-body decays Bc+→K0∗+(1430)D0→K0π+D0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B^+_c \\rightarrow K^{*+}_0(1430) D^{0} \\rightarrow K^0 \\pi ^+ D^{0}$$\\end{document} and Bc+→K0∗0(1430)D+→K+π-D+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B^+_c \\rightarrow K^{*0}_0(1430) D^{+} \\rightarrow K^+ \\pi ^- D^{+}$$\\end{document} have large branching ratios, which can reach to the order of 10-4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$10^{-4}$$\\end{document} and are most likely to be observed in the future LHCb experiments. Furthermore, the branching ratios of the quasi-two-body decays Bc→K0∗(1950)D(s)→KπD(s)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_c \\rightarrow K_0^{*}(1950) D_{(s)} \\rightarrow K \\pi D_{(s)}$$\\end{document} are about one order smaller than those of the corresponding decays Bc→K0∗(1430)D(s)→KπD(s)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_c \\rightarrow K_0^{*}(1430) D_{(s)} \\rightarrow K \\pi D_{(s)}$$\\end{document}.

Production of pentaquarks with hidden charm and double strangeness in Ξb and Ωb decays

Recently, several pentaquark states Pcss, with global flavor c¯cssn, have been predicted within a theoretical framework based on unitary coupled channels. We study theoretically the feasibility to observe the Pcss with I(JP)=12(12−) in the decays Ξb0→ηηcΞ0 and Ωb−→K−ηcΞ0. Indeed, within the model, the ηcΞ0 channel is the lowest mass pseudoscalar-baryon channel to which this pentaquark state couples, thus we can expect to observe its signal in the ηcΞ0 invariant mass distribution of the mentioned decays. We identify the dominant weak decay processes and then implement the hadronization into the different meson-baryon channels in the final state, linked by flavor symmetry. The dominant meson-baryon final state interaction is then implemented to generate the full amplitude, implicitly accounting for the dynamical emergence of the pentaquark states. We obtain a clear Breit-Wigner-like resonant signal in the spectrum of the Ωb− decay, exceeding that in the Ξb0 decay by two to three orders of magnitude. In the case of the latter decay, the resonant state would manifest as a significant dip in the spectrum. We study the feasibility of searching for these b-hadron decay modes and analyzing their resonant components using the current and future data samples from the LHCb experiment. Published by the American Physical Society 2024

Dalitz-plot analysis of B±→K±K+K− decays

We study B±→K±K+K− decays using the QCD factorization model with final state interactions between K+ and K− mesons taken into account. The parameters of the model are fitted to the data of the and LHCb collaborations. We describe the KK¯ effective mass distributions and examine the CP-violating asymmetry effects in the full range of the Dalitz plot. Published by the American Physical Society 2024

Investigating the composition of the K[formula omitted] state with π±K[formula omitted] correlations at the LHC

The first measurements of femtoscopic correlations with the particle pair combinations π±KS0 in pp collisions at s=13 TeV at the Large Hadron Collider (LHC) are reported by the ALICE experiment. Using the femtoscopic approach, it is shown that it is possible to study the elusive K0⁎(700) particle that has been considered a tetraquark candidate for over forty years. Source and final-state interaction parameters are extracted by fitting a model assuming a Gaussian source to the experimentally measured two-particle correlation functions. The final-state interaction in the π±KS0 system is modeled through a resonant scattering amplitude, defined in terms of a mass and a coupling parameter, The extracted mass and Breit–Wigner width, derived from the coupling parameter, of the final-state interaction are found to be consistent with previous measurements of the K0⁎(700). The small value and increase of the correlation strength with increasing source size support the hypothesis that the K0⁎(700) is a four-quark state, i.e. a tetraquark state of the form (q1,q2‾,q3,q3‾) in which q1, q2 and q3 indicate the flavor of the valence quarks of the π and KS0. This latter trend is also confirmed via a simple geometric model that assumes a tetraquark structure of the K0⁎(700) resonance.

Final state rescattering effects in axio-hadronic η and η′ decays

It has been long-understood that final state rescattering effects provide O\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{O} $$\\end{document}(1) corrections to hadronic meson decays rates, such as η → πππ and η′ → ηππ. Hence, one would expect that such effects would be just as important in axio-hadronic η and η′ decays, such as η(′) → ππa, where a is an axion or axion-like particle (ALP). And indeed they are, as we show in this paper by using the treatment of dispersion relations to include the effects of strong final state interactions in several axio-hadronic processes, namely, η(′) → π0π0a, η(′) → π+π−a, and η′ → ηπ0a. We also compute the perturbative, leading order decay rates for multiple ALP emission, such as in η(′) → π0aa, η′ → ηaa and η(′) → aaa, and briefly discuss the expected corrections from strong interactions and the processes that must be considered for an accurate rate estimation of these multi-ALP decay channels.

First Simultaneous Measurement of Differential Muon-Neutrino Charged-Current Cross Sections on Argon for Final States with and without Protons Using MicroBooNE Data.

We report the first double-differential neutrino-argon cross section measurement made simultaneously for final states with and without protons for the inclusive muon neutrino charged-current interaction channel. The proton kinematics of this channel are further explored with a differential cross section measurement as a function of the leading proton's kinetic energy that extends across the detection threshold. These measurements use data collected with the MicroBooNE detector from 6.4×10^{20} protons on target from the Fermilab booster neutrino beam with a mean neutrino energy of ∼0.8 GeV. Extensive data-driven model validation utilizing the conditional constraint formalism is employed. This motivates enlarging the uncertainties with an empirical reweighting approach to minimize the possibility of extracting biased cross section results. The extracted nominal flux-averaged cross sections are compared to widely used event generator predictions revealing severe mismodeling of final states without protons for muon neutrino charged-current interactions, possibly from insufficient treatment of final state interactions. These measurements provide a wealth of new information useful for improving event generators which will enhance the sensitivity of precision measurements in neutrino experiments.

Unveiling the a0(1710) nature in the process J/ψ→K¯0K+ρ−

We have investigated the process J/ψ→K¯0K+ρ− by taking into account the S-wave K*K¯*, ρω, and ρϕ final-state interactions, where the scalar meson a0(1710) is generated. In addition, we also take into account the contributions from the scalar a0(980)(→K¯0K+) and the intermediate resonances K1(1270)−(→K¯0ρ−) and K1(1270)0(→K+ρ−). Our results show that, in the K¯0K+ invariant mass distribution, a clear peak structure around 1.8 GeV appears, which could be associated with the scalar a0(1710), however, no significant structure of the a0(980) is observed. On the other hand, one can find clear peaks of the K1(1270) in the K¯0ρ− and K+ρ− invariant mass distributions. The future precise measurement of this process by the BESIII and Belle II Collaborations and the planned Super Tau-Charm Facility in the future could shed light on the nature of a0(1710). Published by the American Physical Society 2024

Production of hidden-heavy and double-heavy hadronic molecules at the Z factory of CEPC

With a clean environment and high collision energy, the Circular Electron Positron Collider (CEPC) would be an excellent facility for heavy flavor physics. Using the Monte Carlo event generator ythia, we simulate the production of the charmed (bottom) hadron pairs in the electron-positron collisions at the Z factory of CEPC, and the inclusive production rates for typical candidates of the hidden/double-charm and hidden/double-bottom S-wave hadronic molecules are estimated at an order-of-magnitude level with the final state interactions after the hadron pair production. The predicted cross sections for the hidden-charm meson-meson molecules X(3872) and Zc(3900) are at pb level, which are about two to three orders of magnitude larger than the production cross sections for the double-charm meson-meson molecules Tcc and Tcc*, as the double-charmed ones require the production of two pairs of cc¯ from the Z boson decay. The production cross sections for the hidden-charm pentaquark states Pc and Pcs as meson-baryon molecules are a few to tens of fb, which are about one magnitude larger than those of the possible hidden-charm baryon-antibaryon and double-charm meson-baryon molecules. In the bottom sector, the production cross sections for the Zb states as B(*)B¯* molecules are about tens to hundreds of fb, indicating 106–107 events from a two-year operation of CEPC, and the expected events from the double-bottom molecules are about 2–5 orders of magnitude smaller than the Zb states. Our results shows great prospects of probing heavy exotic hadrons at CEPC. Published by the American Physical Society 2024

Final-state interactions in the CP asymmetry of D meson two-body decays

Final-state interactions in the CP asymmetry of <i>D</i> meson two-body decays

Production of D(*)D¯(*) near the thresholds in e+e− annihilation

It is shown that the nontrivial energy dependencies of DD¯, DD¯*, and D*D¯* pair production cross sections in e+e− annihilation are well described within the approach based on an account of the final-state interaction of produced particles. This statement is valid for the production of charged and neutral particles. Interaction of D(*) and D¯(*) is taken into account using the effective potential method. Its applicability is based on the fact that for near-threshold resonance the characteristic width of peak in the wave function is much larger than the interaction radius. The transition amplitudes between all three channels play an important role in the description of cross sections. These transitions are possible since all channels have the same quantum numbers JPC=1−−. Published by the American Physical Society 2024

Study of the timelike electromagnetic form factors of the Λc

In this paper, the reaction of electron-positron annihilation into Λc+Λ¯c− is investigated. The Λc+Λ¯c− scattering amplitudes are obtained by solving the Lippmann-Schwinger equation. The contact, annihilation, and two pseudoscalar-exchange potentials are taken into account in the spirit of the chiral effective field theory. The amplitudes of e+e−→Λc+Λ¯c− are constructed by the distorted wave Born approximation method, with the final state interactions of the Λc+Λ¯c− rescattering implemented. By fitting to the experimental data, the unknown couplings are fixed, and high-quality solutions are obtained. With these amplitudes, the individual electromagnetic form factors in the timelike region, GEΛc, GMΛc, and their ratio, GEΛc/GMΛc, are extracted. Both modulus and phases are predicted. These individual electromagnetic form factors reveal new insights into the properties of the Λc. The separated contributions of the Born term, contact, annihilation, as well as the two pseudoscalar-exchange potentials to the electromagnetic form factors are isolated. It is found that the Born term dominates the whole energy region. The contact term plays a crucial role in the enhancement near the threshold, and the annihilation term is essential in generating the fluctuation of the electromagnetic form factors. Published by the American Physical Society 2024

PΛ¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p\\bar{\\varLambda }$$\\end{document} final-state interaction in the reactions e+e-→K-pΛ¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$e^+e^- \\rightarrow K^- p \\bar{\\varLambda }$$\\end{document} and J/ψ→K-pΛ¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$J/\\psi \\rightarrow K^- p \\bar{\\varLambda }$$\\end{document}

Near-threshold pΛ¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p\\bar{\\Lambda }$$\\end{document} mass spectra for the reactions e+e-→K-pΛ¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$e^+e^- \\rightarrow K^- p\\bar{\\Lambda }$$\\end{document} and J/ψ→K-pΛ¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$J/\\psi \\rightarrow K^- p\\bar{\\Lambda }$$\\end{document} are investigated with an emphasis on the role played by the interaction in the pΛ¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p\\bar{\\Lambda }$$\\end{document} system. As guideline for the pΛ¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p\\bar{\\Lambda }$$\\end{document} interaction a variety of ΛΛ¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda \\bar{\\Lambda }$$\\end{document} potential models is considered that have been established in the analysis of data on pp¯→ΛΛ¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p{\\bar{p}}\\rightarrow \\Lambda \\bar{\\Lambda }$$\\end{document} in the past. Arguments why the properties of the pΛ¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p\\bar{\\Lambda }$$\\end{document} and ΛΛ¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda \\bar{\\Lambda }$$\\end{document} interactions can be expected to be very similar are provided. It is shown that the near-threshold enhancement in the invariant mass observed for the e+e-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$e^+e^-$$\\end{document} reaction can be reproduced quantitatively by the assumed pΛ¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p\\bar{\\Lambda }$$\\end{document} final-state interaction in the partial wave suggested by an amplitude analysis of the experiment. The effect of the pΛ¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p\\bar{\\Lambda }$$\\end{document} final-state interaction in other decays is explored, including the recently measured reactions B-→J/ψp¯Λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B^- \\rightarrow J/\\psi \\, {\\bar{p}} \\Lambda $$\\end{document} and B+→J/ψpΛ¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B^+ \\rightarrow J/\\psi \\, p \\bar{\\Lambda }$$\\end{document}. It is found that the final-state interaction improves the description of the measured invariant mass near threshold in most cases.

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.

Meson production in J/ψ decays and [formula omitted] process

It is shown that an account for the final-state interaction of real or virtual nucleon and antinucleon produced in the processes J/ψ→pp¯γ, ψ(2S)→pp¯γ, J/ψ→pp¯ω, and J/ψ→3(π+π−)γ near the threshold of NN¯ pair production allows one to obtain self-consistent description of these processes. Predictions of our model are in good agreement with experimental data available. The proposed potential model also reproduces the corresponding partial cross sections of pp¯ scattering.

Observation of D^{+}→K_{S}^{0}a_{0}(980)^{+} in the Amplitude Analysis of D^{+}→K_{S}^{0}π^{+}η.

We perform for the first time an amplitude analysis of the decay D^{+}→K_{S}^{0}π^{+}η and report the observation of the decay D^{+}→K_{S}^{0}a_{0}(980)^{+} using 2.93 fb^{-1} of e^{+}e^{-} collision data taken at a center-of-mass energy of 3.773GeV with the BESIII detector. As the only W-annihilation-free decay among D to a_{0}(980) pseudoscalar, D^{+}→K_{S}^{0}a_{0}(980)^{+} is the ideal decay in extracting the contributions of the W-emission amplitudes involving a_{0}(980) and to study the final-state interactions. The absolute branching fraction of D^{+}→K_{S}^{0}π^{+}η is measured to be (1.27±0.04_{stat}±0.03_{syst})%. The branching fractions of intermediate processes D^{+}→K_{S}^{0}a_{0}(980)^{+} with a_{0}(980)^{+}→π^{+}η and D^{+}→π^{+}K[over ¯]_{0}^{*}(1430)^{0} with K[over ¯]_{0}^{*}(1430)^{0}→K_{S}^{0}η are measured to be (1.33±0.05_{stat}±0.04_{syst})% and (0.14±0.03_{stat}±0.01_{syst})%, respectively.

Experimental Study of Cold Dense Nuclear Matter

The fundamental theory of nuclear interactions, Quantum Chromodynamics (QCD), operates in terms of quarks and gluons at higher resolution. At low resolution the relevant degrees of freedom are nucleons. Two-nucleon Short-Range Correlations (SRC) help to interconnect these two descriptions. SRCs are temporary fluctuations of strongly interacting close pairs of nucleons. The distance between the two nucleons is comparable to their radii and their relative momenta are larger than the fermi sea level. According to the electron scattering experiments held in the last decade, SRCs have far-reaching impacts on many-body systems, the nucleon-nucleon interactions, and nuclear substructure. The modern experiments with ion beams and cryogenic liquid hydrogen target make it possible to study properties of the nuclear fragments after quasi-elastic knockout of a single nucleon or an SRC pair. Here we review the status and perspectives of the SRC program in so-called inverse kinematics at JINR (Dubna, Russia). The first SRC experiment at the BM@N spectrometer (2018) with 4 GeV/c/nucleon carbon beam has shown that detection of an intact 11B nucleus after interaction selects out the quasi-elastic knockout reaction with minimal contribution of initial- and final-state interactions. Also, 25 events of SRC-breakups showed agreement in SRC properties as known from electron beam experiments. The analysis of the second measurement of SRC at BM@N held in 2022 with an improved setup is currently ongoing. The SRC project at JINR moved to a new experimental area in 2023, where the next measurement is being planned in terms of experimental setup and physics goals.

Induced Isotensor Interactions in Heavy-Ion Double-Charge-Exchange Reactions and the Role of Initial and Final State Interactions

The role of initial state (ISI) and final state (FSI) ion–ion interactions in heavy-ion double-charge-exchange (DCE) reactions A(Z,N)→A(Z±2,N∓2) are studied for double single-charge-exchange (DSCE) reactions given by sequential actions of the isovector nucleon–nucleon (NN) T-matrix. In momentum representation, the second-order DSCE reaction amplitude is shown to be given in factorized form by projectile and target nuclear matrix elements and a reaction kernel containing ISI and FSI. Expanding the intermediate propagator in a Taylor series with respect to auxiliary energy allows us to perform the summation in the leading-order term over intermediate nuclear states in closure approximation. The nuclear matrix element attains a form given by the products of two-body interactions directly exciting the n2p−2 and p2n−2 DCE transitions in the projectile and the target nucleus, respectively. A surprising result is that the intermediate propagation induces correlations between the transition vertices, showing that DSCE reactions are a two-nucleon process that resembles a system of interacting spin–isospin dipoles. Transformation of the DSCE NN T-matrix interactions from the reaction theoretical t-channel form to the s-channel operator structure required for spectroscopic purposes is elaborated in detail, showing that, in general, a rich spectrum of spin scalar, spin vector and higher-rank spin tensor multipole transitions will contribute to a DSCE reaction. Similarities (and differences) to two-neutrino double-beta decay (DBD) are discussed. ISI/FSI distortion and absorption effects are illustrated in black sphere approximation and in an illustrative application to data.