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J. Haidenbauer

Publications and source records attributed to J. Haidenbauer.

At least 73 records · Page 4Linked to original sources
arXiv2011

Pion photoproduction in a dynamical coupled-channels model

The charged and neutral pion photoproduction reactions are investigated in a dynamical coupled-channels approach based on the formulation of Haberzettl, Huang, and Nakayama [Phys. Rev. C 83, 065502 (2011)]. The hadronic final-state interaction is provided by the Juelich pi-N model, which includes the channels pi-N and eta-N comprising stable hadrons as well as the effective pi-pi-N channels pi-Delta, sigma-N, and rho-N. This hadronic model has been quite successful in describing pi-N to pi-N scattering for center-of-mass energies up to 1.9 GeV. By construction, the full pion photoproduction current satisfies the generalized Ward-Takahashi identity and thus is gauge invariant as a matter of course. The calculated differential cross sections and photon spin asymmetries up to 1.65 GeV center-of-mass energy for the reactions gamma p to pi+ n, gamma p to pi0 p, gamma n to pi- p and gamma n to pi0 n are in good agreement with the experimental data.

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arXiv2011

To bind or not to bind: The H-dibaryon in light of chiral effective field theory

We analyse the quark mass dependence of the binding energy of the H-dibaryon in the framework of chiral effective field theory. We show that the SU(3) breaking effects induced by the differences of the pertinent two-baryon thresholds (Lambda-Lambda, Xi-N, Sigma-Sigma) have a very pronounced impact that need to be incorporated properly in future lattice QCD simulations. We also point out that if the H-dibaryon is a two-baryon bound state, its dominant component is Xi-N rather than Lambda-Lambda, which is a consequence of the approximate SU(3) flavor symmetry of the two-baryon interactions.

hep-ph↗
arXiv2011

Dynamical coupled-channels model study of pion photoproduction

The photoproduction of pion off nucleon is investigated within a dynamical coupled-channels approach based on the Juelich pi-N model, which has been quite successful in the description of pi-N to pi-N scattering for center-of-mass energies up to 1.9 GeV. The full pion photoproduction amplitude is constructed to satisfy the generalized Ward-Takahashi identity and hence, it is fully gauge invariant. The calculated differential cross sections and photon spin asymmetries up to 1.65 GeV center-of-mass energy for the reactions gamma p to pi^+ n, gamma p to pi^0 p and gamma n to pi^- p are in good agreement with the experimental data.

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arXiv2011

DN interaction from the Juelich meson-exchange model

The $DN$ interaction is studied in close analogy to the meson-exchange $\bar KN$ potential of the Juelich group using SU(4) symmetry constraints. The model generates the $Λ_c$(2595) resonance dynamically as a $DN$ quasi-bound state. Results for $DN$ scattering lengths and cross sections are presented and compared with predictions based on the Weinberg-Tomozawa term. Some features of the $Λ_c$(2595) resonance are also discussed emphasizing the role of the near-by $πΣ_c$ threshold.

hep-ph↗
arXiv2011

Antiproton scattering off $^3 He$ and $^4 He$ nuclei at low and intermediate energies

Antiproton scattering off $^3\He$ and $^4\He$ targets is considered at beam energies below 300 MeV within the Glauber-Sitenko approach, utilizing the $\bar N N$ amplitudes of the Jülich model as input. A good agreement with available data on differential $\bar p ^4\He$ cross sections and on $\bar p ^3\He$ and $\pbar ^4\He$ reaction cross sections is obtained. Predictions for polarized total $\bar p ^3$He cross sections are presented, calculated within the single-scattering approximation and including Coulomb-nuclear interference effects. The kinetics of the polarization buildup is discussed.

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arXiv2011

Spin-dependent pbar-d cross sections at low and intermediate energies

Antiproton-deuteron (${\bar p}d$) scattering is calculated at beam energies below 300 MeV within the Glauber approach, utilizing the amplitudes of the Jülich $\bar N N$ models. A good agreement is obtained with available experimental data on upolarized differential and integrated $\bar p d$ cross sections. Predictions for polarized total ${\bar p}d$ cross sections are presented, obtained within the single scattering approximation including Coulomb-nuclear interference effects. It is found that the total longitudinal and transversal ${\bar p}d$ cross sections are comparable in absolute value to those for ${\bar p}p$ scattering. The kinetics of polarization buildup is considered.

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arXiv2011

Spin dependence of the antinucleon-nucleon interaction

The status of our present knowledge on the antinucleon-nucleon interaction at low and medium energies is discussed. Special emphasis is put on aspects related to its spin dependence which are relevant for experiments planned by the PAX collaboration. Predictions for the spin-dependent antiproton-proton cross sections sigma_1 and sigma_2 are presented, utilizing antinucleon-nucleon potential models developed by the Juelich group, and compared to results based on the amplitudes of the Nijmegen partial-wave analysis.

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arXiv2010

Charm production in antiproton-proton annihilation

We study the production of charmed mesons (D) and baryons (Lambda_c) in antiproton-proton (app) annihilation close to their respective production thresholds. The elementary charm production process is described by either baryon/meson exchange or by quark/gluon dynamics. Effects of the interactions in the initial and final states are taken into account rigorously. The calculations are performed in close analogy to our earlier study on app -> antiLambda-Lambda and app -> antiK-K by connecting the processes via SU(4) flavor symmetry. Our predictions for the antiLambda_c-Lambda_c production cross section are in the order of 1 to 7 mb, i.e. a factor of around 10-70 smaller than the corresponding cross sections for antiLambda-Lambda However, they are 100 to 1000 times larger than predictions of other model calculations in the literature. On the other hand, the resulting cross sections for antiD-D production are found to be in the order of 10^{-2} -- 10^{-1} microbarn and they turned out to be comparable to those obtained in other studies.

hep-ph↗
arXiv2010

Analysis of recent eta photoproduction data

Recent data on eta-meson photoproduction off a proton target in the energy range 2 < sqrt{s} < 3 GeV are analyzed with regard to their overall consistency. Results from the ELSA and CLAS measurements are compared with predictions of a Regge model whose reaction amplitude was fixed via a global fit to pre-2000 measurements of differential cross sections and polarization observables for gamma p -> eta p at higher energies. We find that all recent experimental results on differential cross sections for eta-meson photoproduction are in good agreement with each other, except for the CLAS data from 2009. However, the latter can be made consistent with the other data at the expense of introducing an energy-dependent renormalization factor. We point out that there indications in the data for a possible excitation of baryon resonances with masses around 2.1 and 2.4 GeV.

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arXiv2010

DN interaction from meson exchange

A model of the DN interaction is presented which is developed in close analogy to the meson-exchange KbarN potential of the Juelich group utilizing SU(4) symmetry constraints. The main ingredients of the interaction are provided by vector meson (rho, omega) exchange and higher-order box diagrams involving D*N, DΔ, and D*Δintermediate states. The coupling of DN to the pi-Lambda_c and pi-Sigma_c channels is taken into account. The interaction model generates the Lambda_c(2595) resonance dynamically as a DN quasi-bound state. Results for DN total and differential cross sections are presented and compared with predictions of an interaction model that is based on the leading-order Weinberg-Tomozawa term. Some features of the Lambda_c(2595) resonance are discussed and the role of the near-by pi-Sigma_c threshold is emphasized. Selected predictions of the orginal KbarN model are reported too. Specifically, it is pointed out that the model generates two poles in the partial wave corresponding to the Lambda(1405) resonance.

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arXiv2010

Proton-proton scattering above 3 GeV/c

A large set of data on proton-proton differential cross sections, analyzing powers and the double polarization parameter A_NN is analyzed employing the Regge formalism. We find that the data available at proton beam momenta from 3 GeV/c to 50 GeV/c exhibit features that are very well in line with the general characteristics of Regge phenomenology and can be described with a model that includes the rho, omega, f_2, and a_2 trajectories and single Pomeron exchange. Additional data, specifically for spin-dependent observables at forward angles, would be very helpful for testing and refining our Regge model.

hep-ph↗
arXiv2010

Primakoff effect in eta-photoproduction off protons

We analyse data on forward eta-meson photoproduction off a proton target and extract the eta to gamma gamma decay width utilizing the Primakoff effect. The hadronic amplitude that enters into our analysis is strongly constrained because it is fixed from a global fit to available gamma p to p eta data for differential cross sections and polarizations. We compare our results with present information on the two-photon eta-decay from the literature. We provide predictions for future PrimEx experiments at Jefferson Laboratory in order to motivate further studies.

hep-ph↗
arXiv2009

The reaction ppbar -> Lambda_c-Lambda_cbar close to threshold

Predictions for the charm-production reaction antiproton-proton -> antiLambda_c-Lambda_c for energies near the threshold are presented. The calculations are performed in a meson-exchange framework in close analogy to our earlier study on antiproton-proton -> antiLambda-Lambda by connecting the two processes via SU(4) symmetry. The obtained antiLambda_c-Lambda_c production cross sections are in the order of 1 to 7 \mub, i.e. a factor of around 10 smaller than the corresponding cross sections for antiLambda-Lambda. However, they are 100 to 1000 times larger than predictions of other model calculations in the literature.

hep-ph↗
arXiv2009

Extraction of the strong neutron-proton mass difference from the charge symmetry breaking in pn-->d pi0

We perform a complete calculation of charge symmetry breaking effects for the reaction pn -> d pi0 at leading order in chiral perturbation theory. A new leading-order operator is included. From our analysis we extract δm_N^{str}, the strong contribution to the neutron-proton mass difference. The value obtained, δm_N^{str} = 1.5 \pm 0.8 (exp.) \pm 0.5 (th.) MeV, is consistent with the result based on the Cottingham sum rule. This agreement provides a non-trivial test of our current understanding of the chiral structure of QCD.

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arXiv2009

p-Wave pion production from nucleon-nucleon collisions

We investigate p-wave pion production in nucleon-nucleon collisions up to next-to-next-to-leading order in chiral effective field theory. In particular, we show that it is possible to describe simultaneously the p-wave amplitudes in the $pn\to ppπ^-$, $pp\to pnπ^+$, $pp\to dπ^+$ channels by adjusting a single low-energy constant accompanying the short-range operator which is available at this order. This study provides a non-trivial test of the applicability of chiral effective field theory to reactions of the type $NN\to NNπ$.

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arXiv2009

Backward pion-nucleon scattering

A global analysis of the world data on differential cross sections and polarization asymmetries of backward pion-nucleon scattering for invariant collision energies above 3 GeV is performed in a Regge model. Including the $N_α$, $N_γ$, $Δ_δ$ and $Δ_β$ trajectories, we reproduce both angular distributions and polarization data for small values of the Mandelstam variable $u$, in contrast to previous analyses. The model amplitude is used to obtain evidence for baryon resonances with mass below 3 GeV. Our analysis suggests a $G_{39}$ resonance with a mass of 2.83 GeV as member of the $Δ_β$ trajectory from the corresponding Chew-Frautschi plot.

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arXiv2009

Predictions for the strangeness S=-3 and -4 baryon-baryon interactions in chiral effective field theory

The leading order strangeness S=-3 and -4 baryon-baryon interactions are analyzed within chiral effective field theory. The chiral potentials consist of contact terms without derivatives and of one-pseudoscalar-meson exchanges. Assuming SU(3) flavor symmetry those contact terms and the couplings of the pseudoscalar mesons to the baryons are related to the corresponding quantities of the S=-1 hyperon-nucleon channels. Specifically, the values of the pertinent five low-energy constants related to the contact terms are already fixed from our preceeding study of the Lambda-N and Sigma-N systems and thus genuine predictions for the Xi-Lambda, Xi-Sigma, and Xi-Xi interactions can be made. Strong attraction is found in some of the S=-3 and -4 channels, suggesting the possible existence of bound states.

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