arXiv subjects

B. Zauner

Publications and source records attributed to B. Zauner.

At least 19 recordsLinked to original sources

arXiv2026

How elastic unitarity governs resonance peaks and residue phases

Imposing elastic unitarity on resonant amplitudes yields a geometric rule connecting the reaction threshold, S-matrix pole, and Breit-Wigner peak. Validated across six orders of magnitude in energy, from $^5\text{He}$ to the Higgs boson, this rule predicts currently unknown residue phases: $-44(12)^\circ$ for $^5\mathrm{He}$, $-24(7)^\circ$ for $\Sigma(1385)^+$, and $-7(13)^\circ$ for $\Xi(1530)^0$. By inverting this formalism, we determine the $\Upsilon(4S)$ pole from its empirical peak to be $10575(1)-i\,8.3(13)$ MeV, with a $-52(6)^\circ$ phase.

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arXiv2026

Rethinking Partial Widths: Unitary Mixing and the $\Delta(1232)$ Pole Residue

The extracted $\pi N$ partial decay width of the $\Delta(1232)$ systematically exceeds its total width ($2|r|>\Gamma$). We demonstrate this anomaly is a natural consequence of S-matrix unitary mixing. Because exact multi-channel shadow poles are distant and model-dependent, we utilize a heuristic elastic model -- treating the overlapping $\Delta(1600)$ as fully elastic -- to isolate the core mechanism. We show that evaluating a perturbing S-matrix at a state's complex pole systematically inflates the residue magnitude. This proof of principle confirms complex residues reflect global amplitude topology rather than isolated intrinsic properties, challenging naive interpretations of branching fractions.

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arXiv2026

Elastic phase shift analysis reveals the geometric origin of the residue phase

We show that the complex-plane structure of light hadron resonances is governed by a unified geometric framework where the threshold position plays a decisive role. By applying this framework to $\pi\pi$, $\pi K$, and $\pi N$ phase shifts, we show that the residue phase $\theta$ is primarily determined by the geometric phase $\delta_0$ (the angle between pole and real axis seen from the threshold). While vector resonances exhibit excellent alignment with this geometric baseline, scalar resonances show systematic deviations of $10^\circ$--$15^\circ$, which we identify as the dynamical imprint of Adler zeros.

hep-ph↗

arXiv2026

Geometric Constraint on Residue Phases: Resolving the N(2190) Anomaly and Diagnosing Exotic States

We derive a parameter-free geometric constraint on residue phases dictated by the pole-threshold angle. Using the N(2190) anomaly as a test case, this constraint reveals a sign ambiguity in prior data; correcting it yields a phase of $-28^\circ\pm10^\circ$, matching our prediction. This consistency validates the method as a model-independent diagnostic for distinguishing compact from molecular states, offering a rigorous tool for exotic spectroscopy.

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arXiv2025

No hidden physics in resonance pole residue phase

In hadron resonant scattering, there are four fundamental resonant parameters: real and imaginary part of the pole position, and the magnitude and the phase of the residue. Out of the four, the last one is the least understood. The search for the residue phase's physical meaning has focused on model-independent phases of the majority of the lowest-mass resonances. Here, we apply a simple mathematical identity to the amplitude in the complex plane to reveal the exact reason for the noticed regularity and show that there is no room for hidden physical variables in the residue phase.

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arXiv2017

Fundamental properties of resonances

All resonances, from hydrogen nuclei excited by the high-energy gamma rays in deep space to newly discovered particles produced in Large Hadron Collider, should be described by the same fundamental physical quantities. However, two distinct sets of properties are used to describe resonances: the pole parameters (complex pole position and residue) and the Breit-Wigner parameters (mass, width, and branching fractions). There is an ongoing decades-old debate on which of them should be abandoned. In this study of nucleon resonances emerging in the elastic pion-nucleon scattering we discover an intricate interplay of the parameters from both sets, and realize that neither set is completely independent or fundamental on its own.

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arXiv2015

Breit-Wigner phase is a fundamental property of a resonance

In the course of devising a simple method for extraction of the S-matrix poles from the data, an additional fundamental resonance property emerged. It is a reaction invariant quantity, and since it is directly related to the Breit-Wigner parameters, we call it the Breit-Wigner phase beta. We propose that this beta is added in resonant data tables.

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arXiv2013

Model independent extraction of the pole and Breit-Wigner resonance parameters

We show that a slightly modified Breit-Wigner formula can successfully describe the total cross section even for the broad resonances, from light rho(770) to the heavy Z boson. In addition to mass, width, and branching fraction, we include another resonance parameter that turns out to be directly related to the pole residue phase. The new formula has two mathematically equivalent forms: one with the pole, and the other with the Breit-Wigner parameters.

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arXiv2010

Model Independent Extraction of S-Matrix Poles from Experimental Data

By separating data points close to a resonance into intervals, and fitting all possible intervals to a simple pole with constant coherently added background, we obtained a substantial number of convergent fits. After a carefully chosen set of statistical constraints was imposed, we calculated the average of a resonance pole position from the statistically acceptable results. We used this method to find pole positions of Z and N(1440) resonances, and to show that the strong discrepancy between the old and new measurements of the Upsilon(11020) mass stems from specious comparison of the Upsilon(11020) pole with its Breit-Wigner mass.

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arXiv2009

Influence of the eta exchange to the eta production in proton-proton scattering

Eta meson production in the proton-proton scattering is dominated by the low-mass meson exchange. We present a brief study on how the type of the exchanged mesons within coupled-channel and multi-resonance model influences the scattering observables. We show under which circumstances the eta exchange may explain the shape of the observed cross sections, and present a few selected results: total cross section in the full energy range, and the proton-proton energy distribution at 15.5 MeV.

nucl-th↗

arXiv2009

Comment on "Mass and K Lambda coupling of N*(1535)"

It is argued in [1] that when the strong coupling to the K Lambda channel is considered, Breit-Wigner mass of the lightest orbital excitation of the nucleon N(1535) shifts to a lower value. The new value turned out to be smaller than the mass of the lightest radial excitation N(1440), which effectively solved the long-standing problem of conventional constituent quark models. In this Comment we show that it is not the Breit-Wigner mass of N(1535) that is decreased, but its bare mass. [1] B. C. Liu and B. S. Zou, Phys. Rev. Lett. 96, 042002 (2006).

hep-ph↗

arXiv2007

A Missing Link Between Quark-Model Resonant States and Scattering-Matrix Singularities

For last two decades different quark models have predicted diverse, sometimes contradictory collections of resonant states. To choose the best among them, the obtained sets had to be compared to available experimental values. In the absence of a more thorough understanding, quark-model resonant states have been directly identified with scattering-matrix singularities. We demonstrate that these are two closely related, but different physical quantities, and offer a model based on the coupled-channel formalism to connect them in an unambiguous way.

hep-ph↗

arXiv2006

Model-independent resonance parameter extraction using the trace of K and T matrices

A model-independent method for the determination of Breit-Wigner resonance parameters is presented. The method is based on eliminating the dependence on the choice of channel basis by analyzing the trace of the K and T matrices in the coupled-channel formalism, rather than individual matrix elements of the multichannel scattering matrix.

hep-ph↗

arXiv2006

The piN --> etaN data demand the existence of N(1710) P11 resonance reducing the 1700 MeV continuum ambiguity

In spite of prolonged polemics, the agreement on the existence of N(1710) P11 resonance has not until now been reached, and the Particle Data Group declares it as a 3-star resonance only. We show that the proper inclusion of inelastic channels in the coupled-channel formalism indisputably demands the existence of N(1710) P11 state, and that it presumably stays "hidden" within the continuum ambiguity of any typical single channel partial wave analyses. Consequently, its Particle Data Group confidence rating should be raised to a 4-star resonance.

hep-ph↗

arXiv2006

The importance of inelastic channels in eliminating continuum ambiguities in pion-nucleon partial wave analyses

Single channel, single energy partial wave analyses (SE_PWA) are from the first principles non-unique in the inelastic region if only data from elastic channels are used, so we in details discuss mechanisms how the problem is eliminated in pion-nucleon scattering. The "continuum ambiguities" puzzle has been extensively discussed since early 1970es, and two major mechanisms for solving the problem have been suggested: either to ensure the continuity of Argand diagrams by imposing the T-matrix t-channel analyticity (Karlsruhe-Helsinki, VPI/GWU) or to restore the unitarity loss in the kinematical regime where the inelastic channels are successively opened by replacing the standard single channel PWA by the coupled channel formalism (CMB, Zagreb, Kent, Pittsburgh/ANL, Giessen). In both approaches the insufficiency of the single channel data is eliminated by introducing additional constraints using the data from other channels. The importance and physical meaning of the second approach is presented in details, and the significance of inelastic channels for the uniqueness of the partial wave analysis is discussed. The outline of the procedure for utilizing the coupled channel formalism to perform the search for the minimal number/full set of T-matrix poles in the complex energy plane, which connect the quark model predictions to experimental reality, is proposed. The appearance of new, additional resonances unneeded in the sole elastic channel is demonstrated.

hep-ph↗

arXiv2006

The importance of piN → K Lambda process for the pole structure of the P11 partial wave T-matrix in the coupled channel pion-nucleon partial wave analysis

The pole structure of the P11 pion-nucleon partial wave is examined with the emphasis on the 1700 MeV energy domain. The mechanism of eliminating continuum ambiguities in pion-nucleon partial wave analyses by using the coupled channel formalism, presented elsewhere for the piN -> etaN channel, is applied for the piN -> K Lambda channel, with the aim to clarify the issue whether physical reality requires none (VPI/GWU), one (KH80, CMB, Kent, Pittsburgh/ANL, Giessen), or possibly two (Zagreb) poles of the partial wave T-matrix in the 1700 MeV range. The role of second inelastic channel for resolving the dilemma is demonstrated. It is pointed out that the experiments for the piN -> K Lambda and piN -> K Sigma channel, extremely important for the 1700 MeV range, are old and inconclusive so an urgent need for remeasuring that channel is stressed.

hep-ph↗

arXiv2005

The re-analysis of the 1700 MeV structure of the P11 partial wave using the piN->KLambda production data

We have used the Breit-Wigner resonance model with S11, P11 and P13 resonances in the s-channel to re-analyze the old piN -> KLambda data with the aim to establish the origin of the prominent structure in the total cross section in the vicinity of 1700 MeV. In this paper we show that, at least in the Breit-Wigner resonance model, it is not possible to achieve the detailed reproduction of the narrow 1700 MeV total cross section peak using the standard partial widths. We have found the new set of resonance parameters enforcing the experimentally observed structure of the total cross section data simultaneously with the linear dependence of the differential cross sections with the cos(Theta) in the energy range 1650 MeV < W < 1800 MeV. The result is that the P13 partial wave has been strongly attenuated in this model. To understand the phenomenon, a much narrower width of a resonant state, the N(1710) P11 in our case, is required, but then the agreement of the model predictions with total cross section data at higher energies is lost. One way out is to allow for the existence of the second P11 resonance in that energy range. The same feature is shown by the polarization data. Analyzing the qqq or qqqq(qbar) nature of the recommended narrow P11 structure in the neighbourhood of 1700 MeV we re-open (remind of) the possibility that another P11 resonant state exists in addition to the standard N(1710) P11 PDG-resonance, and that one of the two states can be identified with the yet undiscovered cryptoexotic pentaquark state. To clarify the situation, we strongly recommend remeasurement of the piN -> KLambda process in the energy range 1650 MeV < W < 1800 MeV.

hep-ph↗

arXiv2004

The N(1710)P11 state is confirmed in the re-analysis of the pi N --> K Lambda production; it is a good candidate for a non-strange pentaquark

Re-analyzing the old pi N --> K Lambda data, the additional proof is given for the existence of the N(1710) P11 state, critically needed in light of reported observations of exotic Theta(1539) and Xi(1862) pentaquarks. An existing single-resonance model with S11, P11 and P13 Breit-Wiegner resonances in the s-channel has been applied. It has been shown that the standard set of resonant parameters fails to reproduce the shape of the differential cross section. The new resonance parameter determination has been performed keeping in mind the most recent knowledge about nucleon resonances. The extracted set of parameters has confirmed the need for the strong contribution of a N(1710) P11 resonance. The need for any significant contribution of the P13 resonance has been eliminated. To reproduce the total cross section at the same time with the linear dependence of the differential cross sections with the cos(theta) in the energy range 1650 MeV < W < 1800 MeV the P11 resonance can not but be quite narrow.

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