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Publications (39)

nucl-ex2025

Measurement of the Total Compton Scattering Cross Section between 6.5 and 11 GeV

GlueX Collaboration, F. Afzal, C. S. Akondi +148

The total cross section for Compton scattering off atomic electrons, $Î³+e\rightarrowÎ³'+e'$, was measured using photons with energies between 6.5 and 11.1 GeV incident on a $^{9}$ Be…

hep-ph2023

The Present and Future of QCD

P. Achenbach, D. Adhikari, A. Afanasev +400

This White Paper presents the community inputs and scientific conclusions from the Hot and Cold QCD Town Meeting that took place September 23-25, 2022 at MIT, as part of the Nuclea…

nucl-ex2014

The N(1520) 3/2- helicity amplitudes from an energy-independent multipole analysis based on new polarization data on photoproduction of neutral pions

J. Hartmann, H. Dutz, A. V. Anisovich +74

New data on the polarization observables T, P, and H for the reaction $I^^{3} p \to p I ¨ ^{0}$ are reported. The results are extracted from azimuthal asymmetries when a transversely polariz…

nucl-ex2012

Well-established nucleon resonances revisited by double-polarization measurements

A. Thiel, A. V. Anisovich, D. Bayadilov +64

The first measurement is reported of the double-polarization observable G in photoproduction of neutral pions off protons, covering the photon energy range from 620 to 1120 MeV and…

nucl-th2016

The Impact of New Polarization Data from Bonn, Mainz and Jefferson Laboratory on $I^^{3} p \to I ¨ N$ Multipoles

A. V. Anisovich R. Beck, M. DÃ¶ring, M. Gottschall +14

New data on pion-photoproduction off the proton have been included in the partial wave analyses Bonn-Gatchina and SAID and in the dynamical coupled-channel approach JÃ¼lich-Bonn. A…

hep-ph2013

Study of ambiguities in $I ¨ ^{-} p \to I^ K^{0}$ scattering amplitudes

A. V. Anisovich, R. Beck, E. Klempt +4

Amplitudes for the reaction $I ¨ ^{-} p \to I^ K^{0}$ are reconstructed from data on the differential cross section $d I ¨ / d I^c ◯$ , the recoil polarization $P$ , and on the spin rotation paramete…

nucl-th2020

Amplitude- and truncated partial-wave analyses combined: A novel, almost theory-independent single-channel method for extracting photoproduction multipoles directly from measured data

A. Å varc, Y. Wunderlich, L. Tiator

Amplitude- and truncated partial-wave analyses are combined into a single procedure and a novel, almost theory-independent single-channel method for extracting multipoles directly…

hep-ex2026

Baryon-antibaryon photoproduction cross sections off the proton

GlueX Collaboration, F. Afzal, M. Albrecht +137

The GlueX experiment at Jefferson Lab has observed $p p ˉ$ and, for the first time, $I^ I^ˉ $ and $p I^ˉ $ photoproduction from a proton target at photon energies up to 11.6 G…

hep-ph2019

Three-body scattering: Ladders and Resonances

M. Mikhasenko, Y. Wunderlich, A. Jackura +4

We discuss unitarity constraints on the dynamics of a system of three interacting particles. We show how the short-range interaction that describes three-body resonances can be sep…

nucl-ex2021

Observation of a structure in the M $_{p I^\cdot}$ invariant mass distribution near 1700 MeV/ $c^{2}$ in the $I^^{3} p \to p I ¨ ^{0} I^\cdot$ reaction

V. Metag, M. Nanova, J. Hartmann +74

The reaction $I^^{3} p \to p I ¨ ^{0} I^\cdot$ has been studied with the CBELSA/TAPS detector at the electron stretcher accelerator ELSA in Bonn for incident photon energies from thresho…

nucl-th2020

The complete experiment for photoproduction of pseudoscalar mesons in a truncated partial wave analysis

Y. Wunderlich, R. Beck, L. Tiator

The complete experiment problem in the truncated partial wave analysis of pseudoscalar meson photoproduction with suppressed t-channel exchanges is investigated. The focus is set t…

nucl-th2020

Moravcsik's theorem on complete sets of polarization observables reexamined

Y. Wunderlich, P. Kroenert, F. Afzal +1

We revisit Moravcsik's theorem on the unique extraction of amplitudes from polarization observables, which has been originally published in 1985. The proof is (re-) written in a mo…

nucl-ex2019

Measurement of the Helicity Asymmetry $E$ for the reaction $I^^{3} p \to I ¨ ^{0} p$

TAPS collaboration, M. Gottschall, F. Afzal +66

A measurement of the double-polarization observable $E$ for the reaction $I^^{3} p \to I ¨ ^{0} p$ is reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility in Bo…

nucl-ex2018

The Î·'-carbon potential at low meson momenta

M. Nanova, S. Friedrich, V. Metag +58

The production of $I^\cdot^{'}$ mesons in coincidence with forward-going protons has been studied in photon-induced reactions on $^{12}$ C and on a liquid hydrogen (LH $_{2}$ ) target for…

hep-ph2026

Quark--hadron duality in inclusive electron--proton scattering at high $Q^{2}$ : structure functions and truncated moments from CLAS12

Y. Wunderlich, A. Bulgakov, K. Joo +2

We present a high-precision study of quark--hadron duality in inclusive electron--proton scattering in the nucleon resonance region, extending to $Q^{2} \approx 10 GeV^{2}$ , bas…

nucl-th2021

New graphical criterion for the selection of complete sets of polarization observables and its application to single-meson photoproduction as well as electroproduction

Y. Wunderlich

This paper combines the graph-theoretical ideas behind Moravcsik's theorem with a completely analytic derivation of discrete phase-ambiguities, recently published by Nakayama. The…

nucl-th2014

Studies on a complete experiment for single pseudoscalar meson photoproduction

Y. Wunderlich

The complete experiment problem for photoproduction of single pseudoscalar mesons is reviewed briefly. If this problem is investigated in the context of a truncated partial wave an…

nucl-ex2025

Upper Limit on the Photoproduction Cross Section of the Spin-Exotic $I ¨ _{1} (1600)$

GlueX Collaboration, F. Afzal, C. S. Akondi +147

The spin-exotic hybrid meson $I ¨ _{1} (1600)$ is predicted to have a large decay rate to the $I ¨ I ¨ I ¨ $ final state. Using 76.6~pb $^{- 1}$ of data collected with the GlueX detector, we…

nucl-ex2024

Evaluation of the E2/M1 ratio in the $N \to I^ (1232)$ transition from the $I^^{3} p \to p I ¨ ^{0}$ reaction

E. Mornacchi, P. Pedroni, F. Afzal +59

A new data set for the helicity-dependent differential cross section of the single-meson photoproduction reaction $I^^{3} p \to p I ¨ ^{0}$ was obtained for the photon energy interval 150…

nucl-ex2024

Measurement of Spin-Density Matrix Elements in $I^^{++} (1232)$ photoproduction

F. Afzal, C. S. Akondi, M. Albrecht +146

We measure the spin-density matrix elements (SDMEs) of the $I^^{++} (1232)$ in the photoproduction reaction $I^^{3} p \to I ¨ ^{-} I^^{++} (1232)$ with the GlueX experiment in Hall D at Jeffer…

nucl-th2022

Determination of complete experiments using graphs

Y. Wunderlich, P. Kroenert, F. Afzal +1

This work presents ideas for the determination of complete experiments using graphs, which are based on a recently published, modified form of Moravcsik's theorem. The lucid repres…

physics.data-an2020

Determining the dominant partial wave contributions from angular distributions of single- and double-polarization observables in pseudoscalar meson photoproduction

Y. Wunderlich, F. Afzal, A. Thiel +1

This work presents a simple method to determine the significant partial wave contributions to experimentally determined observables in pseudoscalar meson photoproduction. First, fi…

nucl-ex2026

First Results on Nucleon Resonance Electroexcitation Amplitudes from $e p \to e^{'} π^{+} π^{-} p^{'}$ Cross Sections at $W$ from $1.56 - 1.76$ GeV and $Q^{2}$ from $2.0 - 5.0$ GeV $^{2}$

V. I. Mokeev, P. Achenbach, V. D. Burkert +6

The first results on the electroexcitation amplitudes or the $γ_{v} p N^{*}$ electrocouplings for nucleon resonances ( $N^{*}$ s) in the third resonance region are presented. They were obtai…

nucl-th2021

Application of the single-channel, single-energy AA/PWA method to $K^{+} I^$ photoproduction

A. Å varc, Y. Wunderlich, L. Tiator

The new single-channel, single-energy partial wave analysis method based on a simultaneous use of amplitude and partial wave analysis called AA/PWA, developed and tested on $I^\cdot$ ph…

nucl-th2018

A connection between angular dependent phase ambiguities and the uniqueness of the partial wave decomposition

A. Å varc, Y. Wunderlich, H. OsmanoviÄ +8

Unconstrained partial-wave amplitudes obtained at discrete energies from fits to complete sets of experimental data may not vary smoothly with energy, and are in principle non-uniq…

nucl-th2025

Decays of $N^{}$ and $I^^{}$ resonances into $N I ¨ $ , $I^ I ¨ $ , and $N I ¨ $

A. V. Sarantsev, E. Klempt, K. V. Nikonov +7

The decays of $N^{*}$ and $I^^{*}$ resonances into $N I ¨ $ , $I^ I ¨ $ and $N I ¨ $ final states are studied in a coupled-channel analysis of data on pion- and photo-induced reactions. Improvem…

nucl-ex2024

Measurement of the J/ $I ¨ $ photoproduction cross section over the full near-threshold kinematic region

GlueX Collaboration, S. Adhikari, F. Afzal +150

We report the total and differential cross sections for $J / I ¨ $ photoproduction with the large acceptance GlueX spectrometer for photon beam energies from the threshold at 8.2~GeV u…

nucl-ex2016

Momentum dependence of the imaginary part of the $I ¨ $ - and $I^\cdot^{'}$ -nucleus optical potential

S. Friedrich, M. Nanova, V. Metag +57

The photoproduction of $I ¨ $ and $I^\cdot^{'}$ mesons off carbon and niobium nuclei has been measured as a function of the meson momentum for incident photon energies of 1.2-2.9 GeV a…

nucl-th2017

Towards an understanding of discrete ambiguities in truncated partial wave analyses

Y. Wunderlich, A. Å varc, R. L. Workman +2

It is well known that the observables in a single-channel scattering problem remain invariant once the amplitude is multiplied by an overall energy- and angle-dependent phase. This…

nucl-ex2016

Photon asymmetry measurements of $I^^{3} p \to I ¨ ^{0} p$ for E $_{I^}^{3}$ =320 $-$ 650 MeV

S. Gardner, D. Howdle, M. H. Sikora +97

High statistics measurements of the photon asymmetry $I^£$ for the $I^^{3}$ p $\to I ¨ ^{0}$ p reaction have been made in the center of mass energy range W=1214-…

nucl-th2018

From Experimental Data to Pole Parameters in a Direct Way (Angle Dependent Continuum Ambiguity and Laurent + Pietarinen Expansion)

A. Å varc, Y. Wunderlich, H. OsmanoviÄ +8

Unconstrained partial-wave amplitudes obtained at discrete energies from fits to complete sets of eight independent observables which are required to uniquely reconstruct reaction…

nucl-ex2025

Polarization observables in double neutral pion photoproduction

TAPS Collaboration, T. Seifen, J. Hartmann +73

Measurements of target asymmetries and double-polarization observables for the reaction $I^^{3} p \to p I ¨ ^{0} I ¨ ^{0}$ are reported. The data were taken with the CBELSA/TAPS experiment at the…

physics.ins-det2023

The new APD-Based Readout of the Crystal Barrel Calorimeter -- An Overview

TAPS Collaboration, C. Honisch, P. Klassen +47

The Crystal Barrel is an electromagnetic calorimeter consisting of 1380 CsI(Tl) scintillators, and is currently installed at the CBELSA/TAPS experiment where it is used to detect d…

nucl-ex2025

First Measurement of $a_{2}^{0} (1320)$ Polarized Photoproduction Cross Section

GlueX Collaboration, F. Afzal, C. S. Akondi +149

We measure for the first time the differential photoproduction cross section $d I ¨ / d t$ of the $a_{2} (1320)$ meson at an average photon beam energy of 8.5~GeV, using data with an integ…

nucl-ex2024

Measurement of Spin-Density Matrix Elements in $I ¨ (770)$ Production with a Linearly Polarized Photon Beam at $E_{I^}^{3} = 8.2 - 8.8 GeV$

GlueX Collaboration, S. Adhikari, F. Afzal +150

The GlueX experiment at Jefferson Lab studies photoproduction of mesons using linearly polarized $8.5 GeV$ photons impinging on a hydrogen target which is contained within…

nucl-th2016

Amplitude reconstruction from complete experiments and truncated partial-wave expansions

R. L. Workman, L. Tiator, Y. Wunderlich +2

We compare the methods of amplitude reconstruction, for a complete experiment and a truncated partial wave analysis, applied to the photoproduction of pseudo-scalar mesons. The app…

nucl-th2017

Amplitude reconstruction from complete electroproduction experiments and truncated partial-wave expansions

L. Tiator, R. L. Workman, Y. Wunderlich +1

We compare the methods of amplitude reconstruction, for a complete experiment and a truncated partial-wave analysis, applied to the electroproduction of pseudoscalar mesons. We giv…

nucl-th2013

PWA tools in Hadronic Spectroscopy

S. Ceci, M. DÃ¶ring, E. Epple +21

The mini-proceedings of the Workshop on PWA tools in Hadronic Spectroscopy held in Mainz from February 18th to 20th, 2013.

nucl-ex2016

Determination of the real part of the Î·'-Nb optical potential

M. Nanova, S. Friedrich, V. Metag +51

The excitation function and momentum distribution of Î·' mesons have been measured in photoproduction off 93^Nb in the energy range of 1.2-2.9 GeV. The experiment has been performe…

Publications (39)

Measurement of the Total Compton Scattering Cross Section between 6.5 and 11 GeV

The Present and Future of QCD

The N(1520) 3/2- helicity amplitudes from an energy-independent multipole analysis based on new polarization data on photoproduction of neutral pions

Well-established nucleon resonances revisited by double-polarization measurements

The Impact of New Polarization Data from Bonn, Mainz and Jefferson Laboratory on I^3p→I¨N Multipoles

Study of ambiguities in I¨−p→I^K0 scattering amplitudes

Amplitude- and truncated partial-wave analyses combined: A novel, almost theory-independent single-channel method for extracting photoproduction multipoles directly from measured data

Baryon-antibaryon photoproduction cross sections off the proton

Three-body scattering: Ladders and Resonances

Observation of a structure in the MpI^⋅​ invariant mass distribution near 1700 MeV/c2 in the I^3p→pI¨0I^⋅ reaction

The complete experiment for photoproduction of pseudoscalar mesons in a truncated partial wave analysis

Moravcsik's theorem on complete sets of polarization observables reexamined

Measurement of the Helicity Asymmetry E for the reaction I^3p→I¨0p

The Î·'-carbon potential at low meson momenta

Quark--hadron duality in inclusive electron--proton scattering at high Q2: structure functions and truncated moments from CLAS12

New graphical criterion for the selection of complete sets of polarization observables and its application to single-meson photoproduction as well as electroproduction

Studies on a complete experiment for single pseudoscalar meson photoproduction

Upper Limit on the Photoproduction Cross Section of the Spin-Exotic I¨1​(1600)

Evaluation of the E2/M1 ratio in the N→I^(1232) transition from the I^3p​→pI¨0 reaction

Measurement of Spin-Density Matrix Elements in I^++(1232) photoproduction

Determination of complete experiments using graphs

Determining the dominant partial wave contributions from angular distributions of single- and double-polarization observables in pseudoscalar meson photoproduction

First Results on Nucleon Resonance Electroexcitation Amplitudes from ep→e′π+π−p′ Cross Sections at W from 1.56−1.76 GeV and Q2 from 2.0−5.0 GeV2

Application of the single-channel, single-energy AA/PWA method to K+I^ photoproduction

A connection between angular dependent phase ambiguities and the uniqueness of the partial wave decomposition

Decays of N∗ and I^∗ resonances into NI¨, I^I¨, and NI¨

Measurement of the J/I¨ photoproduction cross section over the full near-threshold kinematic region

Momentum dependence of the imaginary part of the I¨- and I^⋅′-nucleus optical potential

Towards an understanding of discrete ambiguities in truncated partial wave analyses

Photon asymmetry measurements of I^3p→I¨0p for EI^3​=320−650 MeV

From Experimental Data to Pole Parameters in a Direct Way (Angle Dependent Continuum Ambiguity and Laurent + Pietarinen Expansion)

Polarization observables in double neutral pion photoproduction

The new APD-Based Readout of the Crystal Barrel Calorimeter -- An Overview

First Measurement of a20​(1320) Polarized Photoproduction Cross Section

Measurement of Spin-Density Matrix Elements in I¨(770) Production with a Linearly Polarized Photon Beam at EI^3​=8.2−8.8GeV

Amplitude reconstruction from complete experiments and truncated partial-wave expansions

Amplitude reconstruction from complete electroproduction experiments and truncated partial-wave expansions

PWA tools in Hadronic Spectroscopy

Determination of the real part of the Î·'-Nb optical potential

The Impact of New Polarization Data from Bonn, Mainz and Jefferson Laboratory on $I^^{3} p \to I ¨ N$ Multipoles

Study of ambiguities in $I ¨ ^{-} p \to I^ K^{0}$ scattering amplitudes

Observation of a structure in the M $_{p I^\cdot}$ invariant mass distribution near 1700 MeV/ $c^{2}$ in the $I^^{3} p \to p I ¨ ^{0} I^\cdot$ reaction

Measurement of the Helicity Asymmetry $E$ for the reaction $I^^{3} p \to I ¨ ^{0} p$

Quark--hadron duality in inclusive electron--proton scattering at high $Q^{2}$ : structure functions and truncated moments from CLAS12

Upper Limit on the Photoproduction Cross Section of the Spin-Exotic $I ¨ _{1} (1600)$

Evaluation of the E2/M1 ratio in the $N \to I^ (1232)$ transition from the $I^^{3} p \to p I ¨ ^{0}$ reaction

Measurement of Spin-Density Matrix Elements in $I^^{++} (1232)$ photoproduction

First Results on Nucleon Resonance Electroexcitation Amplitudes from $e p \to e^{'} π^{+} π^{-} p^{'}$ Cross Sections at $W$ from $1.56 - 1.76$ GeV and $Q^{2}$ from $2.0 - 5.0$ GeV $^{2}$

Application of the single-channel, single-energy AA/PWA method to $K^{+} I^$ photoproduction

Decays of $N^{}$ and $I^^{}$ resonances into $N I ¨ $ , $I^ I ¨ $ , and $N I ¨ $

Measurement of the J/ $I ¨ $ photoproduction cross section over the full near-threshold kinematic region

Momentum dependence of the imaginary part of the $I ¨ $ - and $I^\cdot^{'}$ -nucleus optical potential

Photon asymmetry measurements of $I^^{3} p \to I ¨ ^{0} p$ for E $_{I^}^{3}$ =320 $-$ 650 MeV

First Measurement of $a_{2}^{0} (1320)$ Polarized Photoproduction Cross Section

Measurement of Spin-Density Matrix Elements in $I ¨ (770)$ Production with a Linearly Polarized Photon Beam at $E_{I^}^{3} = 8.2 - 8.8 GeV$