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Comprehensive measurement of $η^\prime$ photoproduction off the proton at $E_γ< 2.4$ $\mathrm{GeV}$
Authors:
N. Muramatsu,
J. K. Ahn,
W. C. Chang,
J. Y. Chen,
M. L. Chu,
S. Daté,
T. Gogami,
H. Hamano,
T. Hashimoto,
Q. H. He,
K. Hicks,
T. Hiraiwa,
Y. Honda,
T. Hotta,
Y. Inoue,
T. Ishikawa,
I. Jaegle,
Y. Kasamatsu,
V. L. Kashevarov,
H. Katsuragawa,
S. Kido,
R. Kobayakawa,
Y. Kon,
S. Masumoto,
Y. Matsumura
, et al. (39 additional authors not shown)
Abstract:
For the spectroscopy of nucleon resonances at the total energies from the $η^\prime$-meson production threshold to $2.32$ $\mathrm{GeV}$, photon beam asymmetries of the reaction $γp \to η^\prime p$ were measured together with total and differential cross sections by analyzing the two decay modes $η^\prime \to γγ$ and $π^0 π^0 η$. New constraints for amplitude decomposition were given by the first-…
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For the spectroscopy of nucleon resonances at the total energies from the $η^\prime$-meson production threshold to $2.32$ $\mathrm{GeV}$, photon beam asymmetries of the reaction $γp \to η^\prime p$ were measured together with total and differential cross sections by analyzing the two decay modes $η^\prime \to γγ$ and $π^0 π^0 η$. New constraints for amplitude decomposition were given by the first-time result of photon beam asymmetries at $E_γ> 1.84$ $\mathrm{GeV}$ and the most precise data of differential cross sections to date at extremely backward $η^\prime$ angles. The possibility of a larger coupling constant of the $η^\prime$-nucleon system to the $N(2250)$ resonance was implied in the partial wave analyses using the present data.
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Submitted 20 February, 2026;
originally announced February 2026.
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Hydrogen-like symmetry in Regge spectrum of light mesons: selection of states
Authors:
S. S. Afonin,
A. V. Sarantsev,
A. M. Tsymbal
Abstract:
We discuss the $(L,n)$-classification of excited light non-strange mesons, where $L$ and $n$ are orbital and radial quantum numbers. The selection of true non-strange quark-antiquark excited states and assigning to them definite $L$ and $n$ is a notoriously confusing problem. Three guiding principles for selection of correct observed states are formulated. They are applied for construction of a ne…
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We discuss the $(L,n)$-classification of excited light non-strange mesons, where $L$ and $n$ are orbital and radial quantum numbers. The selection of true non-strange quark-antiquark excited states and assigning to them definite $L$ and $n$ is a notoriously confusing problem. Three guiding principles for selection of correct observed states are formulated. They are applied for construction of a new $(L,n)$-classification. This classification is consistent both with the approximate Regge form of the spectrum and with the hydrogen-like degeneracy, i.e., the dependence of mass on the sum $L+n$.
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Submitted 13 November, 2025;
originally announced November 2025.
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Partial wave analysis of reactions with four meson final states
Authors:
M. A. Matveev,
A. T. Sitnikov,
A. V. Sarantsev
Abstract:
We construct a formalism which describes the resonances decaying into four pseudoscalar meson final states. This method is fully covariant and can be directly applied for the partial-wave analysis of high statistical data. Two topologies of the process are considered: two intermediate resonances each decaying into two final mesons and cascade decay via three meson intermediate states. In particula…
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We construct a formalism which describes the resonances decaying into four pseudoscalar meson final states. This method is fully covariant and can be directly applied for the partial-wave analysis of high statistical data. Two topologies of the process are considered: two intermediate resonances each decaying into two final mesons and cascade decay via three meson intermediate states. In particular, we consider the production of such states in the central collision reactions and in radiative $J/Ψ$ decay.
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Submitted 22 May, 2025;
originally announced May 2025.
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Measurement of single- and double-polarization observables in the photoproduction of $π^+π^-$~meson pairs off the proton using CLAS at Jefferson Laboratory
Authors:
P. Roy,
S. Cao,
V. Crede,
E. Klempt,
V. A. Nikonov,
A. V. Sarantsev,
V. D. Burkert,
V. Mokeev,
P. Achenbach,
J. S. Alvarado,
W. R. Armstrong,
H. Atac,
H. Avakian,
N. A. Baltzell,
L. Barion,
M. Bashkanov,
M. Battaglieri,
F. Benmokhtar,
A. Bianconi,
A. S. Biselli,
M. Bondi,
F. Bossu,
S. Boiarinov,
K. -T. Brinkmann,
W. J. Briscoe
, et al. (119 additional authors not shown)
Abstract:
The photoproduction of $π^+π^-$ meson pairs off the proton has been studied in the reaction $γp\to p\,π^+π^-$ using the CEBAF Large Acceptance Spectrometer (CLAS) and the frozen-spin target (FROST) in Hall B at the Thomas Jefferson National Accelerator Facility. For the first time, the beam and target asymmetries, $I^{s,c}$ and $P_{x,y}$, have been measured along with the beam-target double-polari…
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The photoproduction of $π^+π^-$ meson pairs off the proton has been studied in the reaction $γp\to p\,π^+π^-$ using the CEBAF Large Acceptance Spectrometer (CLAS) and the frozen-spin target (FROST) in Hall B at the Thomas Jefferson National Accelerator Facility. For the first time, the beam and target asymmetries, $I^{s,c}$ and $P_{x,y}$, have been measured along with the beam-target double-polarization observables, $P^{s,c}_{x,y}$, using a transversely polarized target with center-of-mass energies ranging from 1.51 GeV up to 2.04 GeV. These data and additional $ππ$ photoproduction observables from CLAS and experiments elsewhere were included in a partial-wave analysis within the Bonn-Gatchina framework. Significant contributions from $s$-channel resonance production are observed in addition to $t$-channel exchange processes. The data indicate significant contributions from $N^\ast$ and $Δ^\ast$ resonances in the third and fourth resonance regions.
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Submitted 29 April, 2025;
originally announced April 2025.
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Decays of $N^*$ and $Δ^*$ resonances into $Nρ$, $Δπ$, and $Nσ$
Authors:
A. V. Sarantsev,
E. Klempt,
K. V. Nikonov,
T. Seifen,
U. Thoma,
Y. Wunderlich,
P. Achenbach,
V. D. Burkert,
V. Mokeev,
V. Crede
Abstract:
The decays of $N^*$ and $Δ^*$ resonances into $Nρ$, $Δπ$ and $Nσ$ final states are studied in a coupled-channel analysis of data on pion- and photo-induced reactions. Improvements in the fit were observed when new resonance contributions were introduced. Frequencies for the intermediate isobars $Δ(1232)π$, $Nρ$, $Nσ$ are reported.
The decays of $N^*$ and $Δ^*$ resonances into $Nρ$, $Δπ$ and $Nσ$ final states are studied in a coupled-channel analysis of data on pion- and photo-induced reactions. Improvements in the fit were observed when new resonance contributions were introduced. Frequencies for the intermediate isobars $Δ(1232)π$, $Nρ$, $Nσ$ are reported.
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Submitted 21 October, 2025; v1 submitted 20 March, 2025;
originally announced March 2025.
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Photoproduction of two charged pions off protons in the resonance region
Authors:
A. V. Sarantsev,
E. Klempt,
K. V. Nikonov,
P. Achenbach,
V. D. Burkert,
V. Crede,
V. Mokeev
Abstract:
Photoproduction of charged pions pairs off protons is studied within the invariant masses of the final state hadrons from 1.6 to 2.4 GeV at the Thomas Jefferson National Accelerator Facility with the CLAS detector. The data are included in the Bonn-Gatchina coupled-channel analysis and provide the information necessary to determine the branching fractions for most known nucleon and Delta resonance…
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Photoproduction of charged pions pairs off protons is studied within the invariant masses of the final state hadrons from 1.6 to 2.4 GeV at the Thomas Jefferson National Accelerator Facility with the CLAS detector. The data are included in the Bonn-Gatchina coupled-channel analysis and provide the information necessary to determine the branching fractions for most known nucleon and Delta resonances. Branching ratios are obtained here from an event based likelihood fit.
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Submitted 22 November, 2024;
originally announced November 2024.
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The Covariant Approach for the Radiative Decay of the J/Ψ Meson and Relation to Amplitudes Extracted in the Helicity Basis
Authors:
A. V. Anisovich,
K. V. Nikonov,
A. V. Sarantsev
Abstract:
We have developed the covariant approach for the partial wave analysis of the radiative decay of the vector meson into two pseudoscalar mesons based on the orbital momentum- intrinsic spin decomposition. This allowed us to include the data on the radiative J/Ψ decay into a large data base for analysis of the meson production reactions. The correspondence between partial wave amplitudes extracted i…
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We have developed the covariant approach for the partial wave analysis of the radiative decay of the vector meson into two pseudoscalar mesons based on the orbital momentum- intrinsic spin decomposition. This allowed us to include the data on the radiative J/Ψ decay into a large data base for analysis of the meson production reactions. The correspondence between partial wave amplitudes extracted in our approach and those extracted in the helicity basis is determined.
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Submitted 3 June, 2024;
originally announced June 2024.
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Scalar and tensor mesons in $d\bar d$, $s\bar s$ and $gg\to f_0, f_2$
Authors:
A. V. Sarantsev,
E. Klempt
Abstract:
LHCb data on $B^0\to\jpsi π^+π^-$, $B_{s} ^0\to\jpsi π^+π^-$ and $B_{s} ^0\to\jpsi K^+K^-$ are fitted in a coupled-channel analysis jointly with data on radiative $\jpsi$ decays, $ππ$ elastic scattering and further data sets. Branching ratios for $B_{(s)} ^0\to\jpsi f_0,f_2$ are determined and compared to branching ratios from radiative $J/ψ$ decays. Above 1500\,MeV, only little intensity is obser…
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LHCb data on $B^0\to\jpsi π^+π^-$, $B_{s} ^0\to\jpsi π^+π^-$ and $B_{s} ^0\to\jpsi K^+K^-$ are fitted in a coupled-channel analysis jointly with data on radiative $\jpsi$ decays, $ππ$ elastic scattering and further data sets. Branching ratios for $B_{(s)} ^0\to\jpsi f_0,f_2$ are determined and compared to branching ratios from radiative $J/ψ$ decays. Above 1500\,MeV, only little intensity is observed in $B_{(s)} ^0\to\jpsi f_0,f_2$ decays while in radiative $\jpsi$ decays the intensities peak at 1865\,MeV in the scalar, and at 2210\,MeV in the tensor wave. This pattern is interpreted as further support for the glueball interpretation of $G_0(1865)$ and $G_2(2210)$.
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Submitted 1 October, 2024; v1 submitted 16 November, 2022;
originally announced November 2022.
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Note on the definitions of branching ratios of overlapping resonances
Authors:
V. Burkert,
V. Crede,
E. Klempt,
K. V. Nikonov,
J. A. Oller,
J. R. Peláez,
J. Ruiz de Elvira,
A. V. Sarantsev,
L. Tiator,
U. Thoma,
R. Workman
Abstract:
Branching ratios for the decay of hadrons with large width or near thresholds depend on their definition. We test different definitions and show that rather different branching ratios can be obtained. For wide resonances and for sequential decays with wide intermediate resonances, integration over the spectral functions is mandatory. The tests are performed exploiting the latest solution of the Bo…
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Branching ratios for the decay of hadrons with large width or near thresholds depend on their definition. We test different definitions and show that rather different branching ratios can be obtained. For wide resonances and for sequential decays with wide intermediate resonances, integration over the spectral functions is mandatory. The tests are performed exploiting the latest solution of the Bonn-Gatchina multi-channel analysis and published values for residues of light scalar mesons. For a resonance overlapping with a threshold, in case its pole lies in a non-adjacent sheet, we show how the total width, needed for the branching ratios, does not correspond to the imaginary part of the pole position. We use the Madrid-Krakow dispersive parameterizations to illustrate this situation with the $f_0(980)$.
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Submitted 12 July, 2023; v1 submitted 18 July, 2022;
originally announced July 2022.
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Polarization observables in double neutral pion photoproduction
Authors:
CBELSA/TAPS Collaboration,
:,
T. Seifen,
J. Hartmann,
F. Afzal,
A. V. Anisovich,
R. Beck,
M. Becker,
A. Berlin,
M. Bichow,
K. -Th. Brinkmann,
V. Crede,
M. Dieterle,
H. Dutz,
H. Eberhardt,
D. Elsner,
K. Fornet-Ponse,
St. Friedrich,
F. Frommberger,
Ch. Funke,
M. Gottschall,
M. Grüner,
St. Görtz,
E. Gutz,
Ch. Hammann
, et al. (52 additional authors not shown)
Abstract:
Measurements of target asymmetries and double-polarization observables for the reaction $γp\to pπ^0π^0$ are reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility (Bonn University) using the Bonn frozen-spin butanol (C$_4$H$_9$OH) target, which provided transversely polarized protons. Linearly polarized photons were produced via bremsstrahlung off a diamond crystal. The…
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Measurements of target asymmetries and double-polarization observables for the reaction $γp\to pπ^0π^0$ are reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility (Bonn University) using the Bonn frozen-spin butanol (C$_4$H$_9$OH) target, which provided transversely polarized protons. Linearly polarized photons were produced via bremsstrahlung off a diamond crystal. The data cover the photon energy range from $E_γ$=650 MeV to $E_γ$=2600 MeV and nearly the complete angular range. The results have been included in the BnGa partial wave analysis. Experimental results and the fit agree very well. Observed systematic differences in the branching ratios for decays of $N^*$ and $Δ^*$ resonances are attributed to the internal structure of these excited nucleon states. Resonances which can be assigned to SU(6)$\times$O(3) two-oscillator configurations show larger branching ratios to intermediate states with non-zero intrinsic orbital angular momenta than resonances assigned to one-oscillator configurations.
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Submitted 3 June, 2025; v1 submitted 5 July, 2022;
originally announced July 2022.
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Search for the tensor glueball
Authors:
E. Klempt,
A. V. Sarantsev,
I. Denisenko,
K. V. Nikonov
Abstract:
The tensor glueball is searched for in BESIII data on radiative $J/ψ$ decays into $π^0π^0$ and $K_sK_s$. The $ππ$ invariant mass distribution exhibits an enhancement that can be described by a pole at $(2210\pm 60) -i(180\pm 60)$\,MeV. We speculate if the tensor glueball could be distributed among high-mass tensor mesons.
The tensor glueball is searched for in BESIII data on radiative $J/ψ$ decays into $π^0π^0$ and $K_sK_s$. The $ππ$ invariant mass distribution exhibits an enhancement that can be described by a pole at $(2210\pm 60) -i(180\pm 60)$\,MeV. We speculate if the tensor glueball could be distributed among high-mass tensor mesons.
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Submitted 15 May, 2022;
originally announced May 2022.
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Singlet-octet-glueball mixing of scalar mesons
Authors:
Eberhard Klempt,
Andrey V. Sarantsev
Abstract:
The mixing angles between scalar isoscalar resonances and a scalar glueball are determined from their decays into two pseudoscalar mesons. For $f_0(1370)$ and $f_0(1500)$, at most a small glueball component is admitted by the data. The decay modes of $f_0(1710)$, $f_0(1770)$, $f_0(2020)$, and $f_0(2100)$ require significant glueball fractions. Above this mass, the errors in the decay frequencies b…
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The mixing angles between scalar isoscalar resonances and a scalar glueball are determined from their decays into two pseudoscalar mesons. For $f_0(1370)$ and $f_0(1500)$, at most a small glueball component is admitted by the data. The decay modes of $f_0(1710)$, $f_0(1770)$, $f_0(2020)$, and $f_0(2100)$ require significant glueball fractions. Above this mass, the errors in the decay frequencies become too large to extract a glueball component. The summation of all observed glueball fractions up to 2100\,MeV yields (78\er18)\%. The glueball fractions as function of the mass are consistent with a scalar glueball at 1965\,MeV and a width of 370\,MeV as suggested by a measurement of the yield of scalar isoscalar mesons in radiative $J/ψ$ decays.
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Submitted 14 January, 2022; v1 submitted 8 December, 2021;
originally announced December 2021.
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Scalar isoscalar mesons and the scalar glueball from radiative $J/ψ$ decays
Authors:
Andrey V. Sarantsev,
Igor Denisenko,
Ulrike Thoma,
Eberhard Klempt
Abstract:
A coupled-channel analysis of BESIII data on radiative $J/ψ$ decays into $ππ$, $K\bar K$, $ηη$ and $ωφ$ has been performed. The partial-wave amplitude is constrained by a large number of further data. The analysis finds ten isoscalar scalar mesons. Their masses, widths and decay modes are determined. The scalar mesons are interpreted as mainly SU(3)-singlet and mainly octet states. Octet isoscalar…
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A coupled-channel analysis of BESIII data on radiative $J/ψ$ decays into $ππ$, $K\bar K$, $ηη$ and $ωφ$ has been performed. The partial-wave amplitude is constrained by a large number of further data. The analysis finds ten isoscalar scalar mesons. Their masses, widths and decay modes are determined. The scalar mesons are interpreted as mainly SU(3)-singlet and mainly octet states. Octet isoscalar scalar states are observed with significant yields only in the 1500-2100\,MeV mass region. Singlet scalar mesons are produced over a wide mass range but their yield peaks in the same mass region. The peak is interpreted as scalar glueball. Its mass and width are determined to $M=1865$\er25$^{+10}_{-30}$ {\rm MeV} and $Γ= 370$\er$50^{+30}_{-20}$ {\rm MeV}, its yield in radiative $J/ψ$ decays to ($5.8\pm 1.0)\,10^{-3}$.
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Submitted 25 March, 2021; v1 submitted 17 March, 2021;
originally announced March 2021.
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Partial decay widths of baryons in the spin-momentum operator expansion method
Authors:
A. V. Sarantsev
Abstract:
The covariant operator expansion method used by the Bonn-Gatchina group for the analysis of the meson photoproduction data is extended on the case of meson electro-production reactions. The angular dependence of the partial waves is deduced and the obtained amplitudes are compared with those used in other analyses of the electro-production reactions
The covariant operator expansion method used by the Bonn-Gatchina group for the analysis of the meson photoproduction data is extended on the case of meson electro-production reactions. The angular dependence of the partial waves is deduced and the obtained amplitudes are compared with those used in other analyses of the electro-production reactions
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Submitted 9 December, 2020;
originally announced December 2020.
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Observation of a cusp-like structure in the $γp \rightarrow K^+Σ^0$ cross section at forward angles and low momentum transfer
Authors:
T. C. Jude,
S. Alef,
P. Bauer,
D. Bayadilov,
R. Beck,
A. Bella,
J. Bieling,
A. Braghieri,
P. L. Cole,
D. Elsner,
R. Di Salvo,
A. Fantini,
O. Freyermuth,
F. Frommberger,
F. Ghio,
S. Goertz,
A. Gridnev,
D. Hammann,
J. Hannappel,
K. Kohl,
N. Kozlenko,
A. Lapik P. Levi Sandri,
V. Lisin,
G. Mandaglio,
F. Messi
, et al. (17 additional authors not shown)
Abstract:
The $γp \rightarrow K^+Σ^0$ differential cross section at extremely forward angles was measured at the BGOOD experiment. A three-quarter drop in strength over a narrow range in energy and a strong dependence on the polar angle of the $K^+$ in the centre-of-mass of the reaction is observed at a centre-of-mass energy of 1900\,MeV. Residing close to multiple open and hidden strangeness thresholds, th…
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The $γp \rightarrow K^+Σ^0$ differential cross section at extremely forward angles was measured at the BGOOD experiment. A three-quarter drop in strength over a narrow range in energy and a strong dependence on the polar angle of the $K^+$ in the centre-of-mass of the reaction is observed at a centre-of-mass energy of 1900\,MeV. Residing close to multiple open and hidden strangeness thresholds, the structure appears consistent with meson-baryon threshold effects which may contribute to the reaction mechanism.
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Submitted 4 August, 2021; v1 submitted 22 June, 2020;
originally announced June 2020.
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$K^+Λ$ photoproduction at forward angles and low momentum transfer
Authors:
S. Alef,
P. Bauer,
D. Bayadilov,
R. Beck,
A. Bella,
J. Bieling,
A. Braghieri,
P. L. Cole,
D. Elsner,
R. Di Salvo,
A. Fantini,
O. Freyermuth,
F. Frommberger,
F. Ghio,
S. Goertz,
A. Gridnev,
D. Hammann,
J. Hannappel,
T. C. Jude,
K. Kohl,
N. Kozlenko,
A. Lapik P. Levi Sandri,
V. Lisin,
G. Mandaglio,
F. Messi
, et al. (17 additional authors not shown)
Abstract:
$γp \rightarrow K^+ Λ$ differential cross sections and recoil polarisation data from threshold for extremely forward angles are presented. The measurements were performed at the BGOOD experiment at ELSA, utilising the high angular and momentum resolution forward spectrometer for charged particle identification. The data discriminates between conflicting results in the world data set and enable ext…
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$γp \rightarrow K^+ Λ$ differential cross sections and recoil polarisation data from threshold for extremely forward angles are presented. The measurements were performed at the BGOOD experiment at ELSA, utilising the high angular and momentum resolution forward spectrometer for charged particle identification. The data discriminates between conflicting results in the world data set and enable extraction of the cross section as the minimum momentum transfer to the recoiling hyperon is approached.
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Submitted 1 March, 2021; v1 submitted 22 June, 2020;
originally announced June 2020.
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New narrow LHCb pentaquarks as lowest antiquark-diquark-diquark systems
Authors:
A. N. Semenova,
V. V. Anisovich,
A. V. Sarantsev
Abstract:
The antiquark-diquark-diquark model describes pentaquark states both in terms of quarks and hadrons. We discuss pentaquark states with hidden charm $P(\bar c cuud)$ discovered in the $J/Ψp$ spectrum by the LHCb collaboration. We consider three pentaquark states as members of the lowest ($S$-wave) multiplet and discuss the mass splitting scheme. The latest LHCb data for pentaquarks with hidden char…
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The antiquark-diquark-diquark model describes pentaquark states both in terms of quarks and hadrons. We discuss pentaquark states with hidden charm $P(\bar c cuud)$ discovered in the $J/Ψp$ spectrum by the LHCb collaboration. We consider three pentaquark states as members of the lowest ($S$-wave) multiplet and discuss the mass splitting scheme. The latest LHCb data for pentaquarks with hidden charm provide an opportunity to make an assumption about the diquark content of the pentaquark states. We give a classification for the LHCb pentaquarks and define recombination channels for these states.
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Submitted 28 April, 2020; v1 submitted 27 November, 2019;
originally announced November 2019.
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Hyperon II: Properties of excited hyperons
Authors:
A. V. Sarantsev,
M. Matveev,
V. A. Nikonov,
A. V. Anisovich,
U. Thoma,
E. Klempt
Abstract:
We report properties of $Λ$ and $Σ$ hyperon resonances formed in $K^-$ induced reactions. Special emphasis is laid on the analysis of the three-body final states $2π^0Λ$ and $2π^0Σ$ and of the quasi-two-body final states $πΛ(1520)$, $\bar KΔ(1232)$, $πΣ(1385)$, $\bar K^*N$, and $ωΛ$. We give pole positions of $Λ$ and $Σ$ hyperon resonances and transition residues from the $K^-p$ initial to various…
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We report properties of $Λ$ and $Σ$ hyperon resonances formed in $K^-$ induced reactions. Special emphasis is laid on the analysis of the three-body final states $2π^0Λ$ and $2π^0Σ$ and of the quasi-two-body final states $πΛ(1520)$, $\bar KΔ(1232)$, $πΣ(1385)$, $\bar K^*N$, and $ωΛ$. We give pole positions of $Λ$ and $Σ$ hyperon resonances and transition residues from the $K^-p$ initial to various final states as well as Breit-Wigner masses and widths and decay branching ratios. Twenty resonances and "bumps" reported in the Review of Particle Physics are not required in our fits, evidence for five new resonances is reported. The observed mass spectrum is compared to the spectrum calculated in the Bonn quark model. Three spin doublets, six $Λ$ hyperons, are tentatively assigned to the SU(3) singlet system.
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Submitted 31 July, 2019;
originally announced July 2019.
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Hyperon I: Study of the $Λ(1405)$
Authors:
A. V. Anisovich,
A. V. Sarantsev,
V. A. Nikonov,
V. Burkert,
R. A. Schumacher,
U. Thoma,
E. Klempt
Abstract:
Low-energy data on the three charge states in $γp \to K^+(Σπ)$ from CLAS at JLab, on $K^-p\to π^0π^0Λ$ and $π^0π^0Σ$ from the Crystal Ball at BNL, bubble chamber data on $K^-p\toπ^-π^+π^{\pm}Σ^{\mp}$, low-energy total cross sections on $K^-$ induced reactions, and data on the $K^-p$ atom are fitted with the BnGa partial-wave-analysis program. We find that the data can be fitted well with just one…
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Low-energy data on the three charge states in $γp \to K^+(Σπ)$ from CLAS at JLab, on $K^-p\to π^0π^0Λ$ and $π^0π^0Σ$ from the Crystal Ball at BNL, bubble chamber data on $K^-p\toπ^-π^+π^{\pm}Σ^{\mp}$, low-energy total cross sections on $K^-$ induced reactions, and data on the $K^-p$ atom are fitted with the BnGa partial-wave-analysis program. We find that the data can be fitted well with just one isoscalar spin-1/2 negative-parity pole, the $Λ(1405)$, and background contributions.
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Submitted 14 May, 2019;
originally announced May 2019.
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First Measurements of the Double-Polarization Observables $F$, $P$, and $H$ in $ω$ Photoproduction off Transversely Polarized Protons in the $N^\ast$ Resonance Region
Authors:
P. Roy,
S. Park,
V. Crede,
A. V. Anisovich,
E. Klempt,
V. A. Nikonov,
A. V. Sarantsev,
N. C. Wei,
F. Huang,
K. Nakayama,
K. P. Adhikari,
S. Adhikari,
G. Angelini,
H. Avakian,
L. Barion,
M. Battaglieri,
I. Bedlinskiy,
A. S. Biselli,
S. Boiarinov,
W. J. Briscoe,
J. Brock,
W. K. Brooks,
V. D. Burkert,
F. Cao,
C. Carlin
, et al. (123 additional authors not shown)
Abstract:
First measurements of double-polarization observables in $ω$ photoproduction off the proton are presented using transverse target polarization and data from the CEBAF Large Acceptance Spectrometer (CLAS) FROST experiment at Jefferson Lab. The beam-target asymmetry $F$ has been measured using circularly polarized, tagged photons in the energy range 1200 - 2700 MeV, and the beam-target asymmetries…
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First measurements of double-polarization observables in $ω$ photoproduction off the proton are presented using transverse target polarization and data from the CEBAF Large Acceptance Spectrometer (CLAS) FROST experiment at Jefferson Lab. The beam-target asymmetry $F$ has been measured using circularly polarized, tagged photons in the energy range 1200 - 2700 MeV, and the beam-target asymmetries $H$ and $P$ have been measured using linearly polarized tagged photons in the energy range 1200 - 2000 MeV. These measurements significantly increase the database on polarization observables. The results are included in two partial-wave analyses and reveal significant contributions from several nucleon ($N^\ast$) resonances. In particular, contributions from new $N^\ast$ resonances listed in the Review of Particle Properties are observed, which aid in reaching the goal of mapping out the nucleon resonance spectrum.
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Submitted 1 May, 2019; v1 submitted 5 December, 2018;
originally announced December 2018.
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Beam-Target Helicity Asymmetry $E$ in $K^{0}Λ$ and $K^{0}Σ^0$ Photoproduction on the Neutron
Authors:
CLAS Collaboration,
D. H. Ho,
R. A. Schumacher,
A. D'Angelo,
A. Deur,
J. Fleming,
C. Hanretty,
T. Kageya,
F. J. Klein,
E. Klempt,
M. M. Lowry,
H. Lu,
V. A. Nikonov,
P. Peng,
A. M. Sandorfi,
A. V. Sarantsev,
I. I. Strakovsky,
N. K. Walford,
X. Wei,
R. L. Workman,
K. P. Adhikari,
S. Adhikari,
D. Adikaram,
Z. Akbar,
J. Ball
, et al. (124 additional authors not shown)
Abstract:
We report the first measurements of the $E$ beam-target helicity asymmetry for the $\vecγ \vec{n} \to K^{0}Λ$, and $K^{0}Σ^{0}$ channels in the energy range 1.70$\leq W\leq$2.34 GeV. The CLAS system at Jefferson Lab uses a circularly polarized photon beam and a target consisting of longitudinally polarized solid molecular hydrogen deuteride with low background contamination for the measurements. T…
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We report the first measurements of the $E$ beam-target helicity asymmetry for the $\vecγ \vec{n} \to K^{0}Λ$, and $K^{0}Σ^{0}$ channels in the energy range 1.70$\leq W\leq$2.34 GeV. The CLAS system at Jefferson Lab uses a circularly polarized photon beam and a target consisting of longitudinally polarized solid molecular hydrogen deuteride with low background contamination for the measurements. The multivariate analysis method boosted decision trees was used to isolate the reactions of interest. Comparisons with predictions from the KaonMAID, SAID, and Bonn-Gatchina models are presented. These results will help separate the isospin $I=0$ and $I=1$ photo-coupling transition amplitudes in pseudoscalar meson photoproduction.
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Submitted 16 October, 2018; v1 submitted 11 May, 2018;
originally announced May 2018.
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Proton-$η^\prime$ interactions at threshold
Authors:
A. V. Anisovich,
V. Burkert,
M. Dugger,
E. Klempt,
V. A. Nikonov,
B. G. Ritchie,
A. V. Sarantsev,
U. Thoma
Abstract:
Recent data on photoproduction of $η'$ mesons off protons have been included in the data base for the Bonn-Gatchina partial wave analysis. The real and imaginary parts of the $S$-wave $η^\prime p\to η^\prime p$ scattering amplitude in the threshold region were fit to yield the $η^\prime p$ scattering length and the interaction range. This new analysis found…
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Recent data on photoproduction of $η'$ mesons off protons have been included in the data base for the Bonn-Gatchina partial wave analysis. The real and imaginary parts of the $S$-wave $η^\prime p\to η^\prime p$ scattering amplitude in the threshold region were fit to yield the $η^\prime p$ scattering length and the interaction range. This new analysis found $|a_{η^\prime p}|= (0.403\pm 0.015\pm 0.060)$ fm and a phase $φ=(87\pm2)^\circ$, while the range parameter is not well-constrained. The striking behavior of the GRAAL data on the beam asymmetry in the threshold region suggests that a narrow proton-$η'$ resonance might exist. However, the scattering length was found to be relatively insensitive to the possible existence of this narrow resonance.
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Submitted 19 March, 2018;
originally announced March 2018.
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Differential technique for the covariant orbital angular momentum operators
Authors:
M. A. Matveev,
A. V. Sarantsev,
K. M. Semenov-Tian-Shansky,
A. N. Semenova
Abstract:
The orbital angular momentum operator expansion turns to be a powerful tool to construct the fully covariant partial wave amplitudes of hadron decay reactions and hadron photo- and electroproduction processes. In this paper we consider a useful development of the orbital angular momentum operator expansion method. We present the differential technique allowing the direct calculation of convolution…
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The orbital angular momentum operator expansion turns to be a powerful tool to construct the fully covariant partial wave amplitudes of hadron decay reactions and hadron photo- and electroproduction processes. In this paper we consider a useful development of the orbital angular momentum operator expansion method. We present the differential technique allowing the direct calculation of convolutions of two orbital angular momentum operators with an arbitrary number of open Lorentz indices. This differential technique greatly simplifies calculations when the reaction subject to the partial wave analysis involves high spin particles in the initial and/or final states. We also present a useful generalization of the orbital angular momentum operators.
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Submitted 22 February, 2018;
originally announced February 2018.
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Strong evidence for nucleon resonances near 1900\,MeV
Authors:
A. V. Anisovich,
V. Burkert,
M. Hadžimehmedović,
D. G. Ireland,
E. Klempt,
V. A. Nikonov,
R. Omerović,
H. Osmanović,
A. V. Sarantsev,
J. Stahov,
A. Švarc,
U. Thoma
Abstract:
Data on the reaction $γp\to K^+Λ$ from the CLAS experiments are used to derive the leading multipoles, $E_{0+}$, $M_{1-}$, $E_{1+}$, and $M_{1+}$, from the production threshold to 2180\,MeV in 24 slices of the invariant mass. The four multipoles are determined without any constraints. The multipoles are fitted using a multichannel $L+P$ model which allows us to search for singularities and to extr…
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Data on the reaction $γp\to K^+Λ$ from the CLAS experiments are used to derive the leading multipoles, $E_{0+}$, $M_{1-}$, $E_{1+}$, and $M_{1+}$, from the production threshold to 2180\,MeV in 24 slices of the invariant mass. The four multipoles are determined without any constraints. The multipoles are fitted using a multichannel $L+P$ model which allows us to search for singularities and to extract the positions of poles on the complex energy plane in an almost model-independent method. The multipoles are also used as additional constraints in an energy-dependent analysis of a large body of pion and photo-induced reactions within the Bonn-Gatchina (BnGa) partial wave analysis. The study confirms the existence of poles due to nucleon resonances with spin-parity $J^P = 1/2^-; 1/2^+$, and $3/2^+$ in the region at about 1.9\,GeV.
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Submitted 20 December, 2017;
originally announced December 2017.
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$N^*$ resonances from $KΛ$ amplitudes in sliced bins in energy
Authors:
A. V. Anisovich,
V. Burkert,
M. Hadžimehmedović,
D. G. Ireland,
E. Klempt,
V. A. Nikonov,
R. Omerović,
A. V. Sarantsev,
J. Stahov,
A. Švarc,
U. Thoma
Abstract:
The two reactions $γp\to K^+Λ$ and $π^-p\to K^0Λ$ are analyzed to determine the leading photoproduction multipoles and the pion-induced partial wave amplitudes in slices of the invariant mass. The multipoles and the partial-wave amplitudes are simultaneously fitted in a multichannel Laurent+Pietarinen model (L+P model), which determines the poles in the complex energy plane on the second Riemann s…
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The two reactions $γp\to K^+Λ$ and $π^-p\to K^0Λ$ are analyzed to determine the leading photoproduction multipoles and the pion-induced partial wave amplitudes in slices of the invariant mass. The multipoles and the partial-wave amplitudes are simultaneously fitted in a multichannel Laurent+Pietarinen model (L+P model), which determines the poles in the complex energy plane on the second Riemann sheet close to the physical axes. The results from the L+P fit are compared with the results of an energy-dependent fit based on the Bonn-Gatchina (BnGa) approach. The study confirms the existence of several poles due to nucleon resonances in the region at about 1.9\,GeV with quantum numbers $J^P = 1/2^+$, $3/2^+, 1/2^-, 3/2^-, 5/2^-$.
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Submitted 20 December, 2017;
originally announced December 2017.
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Diquark-diquark-antiquark model for pentaquarks with hidden charm: current status and problems
Authors:
V. V. Anisovich,
M. A. Matveev,
J. Nyiri,
A. V. Sarantsev,
A. N. Semenova
Abstract:
The $J/ψp$ signals at 4380 MeV and 4450 MeV which were seen by the LHCb collaboration in the decay $Λ^0_b\to K^-J/ψp$ are discussed following the hypothesis of the existence of diquark-diquark-antiquark composite states. The discussed problems concern: (i) estimation of masses and mass splittings for low-lying states, (ii) determination of decay modes in the quark recombination scheme, (iii) unita…
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The $J/ψp$ signals at 4380 MeV and 4450 MeV which were seen by the LHCb collaboration in the decay $Λ^0_b\to K^-J/ψp$ are discussed following the hypothesis of the existence of diquark-diquark-antiquark composite states. The discussed problems concern: (i) estimation of masses and mass splittings for low-lying states, (ii) determination of decay modes in the quark recombination scheme, (iii) unitarity and analyticity constrains for pentaquark propagators, (iv) hadronic deuteron-like components in the diquark-diquark-antiquark multiplet.
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Submitted 29 November, 2017;
originally announced November 2017.
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Measurement of the beam asymmetry $Σ$ and the target asymmetry $T$ in the photoproduction of $ω$ mesons off the proton using CLAS at Jefferson Laboratory
Authors:
P. Roy,
Z. Akbar,
S. Park,
V. Crede,
A. V. Anisovich,
I. Denisenko,
E. Klempt,
V. A. Nikonov,
A. V. Sarantsev,
K. P. Adhikari,
S. Adhikari,
S. Anefalos Pereira,
J. Ball,
I. Balossino,
M. Bashkanov,
M. Battaglieri,
V. Batourine,
I. Bedlinskiy,
A. S. Biselli,
S. Boiarinov,
W. J. Briscoe,
J. Brock,
W. K. Brooks,
V. D. Burkert,
C. Carlin
, et al. (121 additional authors not shown)
Abstract:
The photoproduction of $ω$ mesons off the proton has been studied in the reaction $γp\to p\,ω$ using the CEBAF Large Acceptance Spectrometer (CLAS) and the frozen-spin target (FROST) in Hall B at the Thomas Jefferson National Accelerator Facility. For the first time, the target asymmetry, $T$, has been measured in photoproduction from the decay $ω\toπ^+π^-π^0$, using a transversely-polarized targe…
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The photoproduction of $ω$ mesons off the proton has been studied in the reaction $γp\to p\,ω$ using the CEBAF Large Acceptance Spectrometer (CLAS) and the frozen-spin target (FROST) in Hall B at the Thomas Jefferson National Accelerator Facility. For the first time, the target asymmetry, $T$, has been measured in photoproduction from the decay $ω\toπ^+π^-π^0$, using a transversely-polarized target with energies ranging from just above the reaction threshold up to 2.8 GeV. Significant non-zero values are observed for these asymmetries, reaching about 30-40% in the third-resonance region. New measurements for the photon-beam asymmetry, $Σ$, are also presented, which agree well with previous CLAS results and extend the world database up to 2.1 GeV. These data and additional $ω$-photoproduction observables from CLAS were included in a partial-wave analysis within the Bonn-Gatchina framework. Significant contributions from $s$-channel resonance production were found in addition to $t$-channel exchange processes.
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Submitted 10 May, 2018; v1 submitted 14 November, 2017;
originally announced November 2017.
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Measurement of the helicity asymmetry $E$ in $ω\toπ^+π^-π^0$ photoproduction
Authors:
Z. Akbar,
P. Roy,
S. Park,
V. Crede,
A. V. Anisovich,
I. Denisenko,
E. Klempt,
V. A. Nikonov,
A. V. Sarantsev,
K. P. Adhikari,
S. Adhikari,
M. J. Amaryan,
S. Anefalos Pereira,
H. Avakian,
J. Ball,
M. Battaglieri,
V. Batourine,
I. Bedlinskiy,
S. Boiarinov,
W. J. Briscoe,
J. Brock,
W. K. Brooks,
V. D. Burkert,
F. T. Cao,
C. Carlin
, et al. (109 additional authors not shown)
Abstract:
The double-polarization observable $E$ was studied for the reaction $γp\to pω$ using the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B at the Thomas Jefferson National Accelerator Facility and the longitudinally-polarized frozen-spin target (FROST). The observable was measured from the charged decay mode of the meson, $ω\toπ^+π^-π^0$, using a circularly-polarized tagged-photon beam with ene…
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The double-polarization observable $E$ was studied for the reaction $γp\to pω$ using the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B at the Thomas Jefferson National Accelerator Facility and the longitudinally-polarized frozen-spin target (FROST). The observable was measured from the charged decay mode of the meson, $ω\toπ^+π^-π^0$, using a circularly-polarized tagged-photon beam with energies ranging from the $ω$ threshold at 1.1 to 2.3 GeV. A partial-wave analysis within the Bonn-Gatchina framework found dominant contributions from the $3/2^+$ partial wave near threshold, which is identified with the sub-threshold $N(1720)\,3/2^+$ nucleon resonance. To describe the entire data set, which consisted of $ω$ differential cross sections and a large variety of polarization observables, further contributions from other nucleon resonances were found to be necessary. With respect to non-resonant mechanisms, $π$ exchange in the $t$-channel was found to remain small across the analyzed energy range, while pomeron $t$-channel exchange gradually grew from the reaction threshold to dominate all other contributions above $W \approx 2$ GeV.
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Submitted 3 January, 2018; v1 submitted 8 August, 2017;
originally announced August 2017.
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Measurement of the Differential and Total Cross Sections of the $γd \to K^0 Λ (p)$ Reaction within the Resonance Region
Authors:
N. Compton,
C. E. Taylor,
K. Hicks,
P. Cole,
N. Zachariou,
Y. Ilieva,
P. Nadel-Turonski,
E. Klempt,
V. A. Nikonov,
A. V. Sarantsev,
the CLAS Collaboration
Abstract:
We report the first measurement of differential and total cross sections for the $γd \to K^0Λ(p)$ reaction, using data from the CLAS detector at the Thomas Jefferson National Accelerator Facility. Data collected during two separate experimental runs were studied with photon-energy coverage 0.8 - 3.6 GeV and 0.5 - 2.6 GeV, respectively. The two measurements are consistent giving confidence in the m…
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We report the first measurement of differential and total cross sections for the $γd \to K^0Λ(p)$ reaction, using data from the CLAS detector at the Thomas Jefferson National Accelerator Facility. Data collected during two separate experimental runs were studied with photon-energy coverage 0.8 - 3.6 GeV and 0.5 - 2.6 GeV, respectively. The two measurements are consistent giving confidence in the method and determination of systematic uncertainties. The cross sections are compared with predictions from the KAON-MAID theoretical model (without kaon exchange), which deviate from the data at higher W and at forward kaon angles. These data, along with previously published cross sections for $K^+ Λ$ photoproduction, provide essential constraints on the nucleon resonance spectrum. A first partial wave analysis has been performed that describes the data without the introduction of new resonances.
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Submitted 15 June, 2017; v1 submitted 15 June, 2017;
originally announced June 2017.
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The Beam-Target Helicity Asymmetry for $\vecγ \vec{n} \rightarrow π^- p$ in the {\bf{$N^*$} Resonance Region
Authors:
D. Ho,
P. Peng,
C. Bass,
P. Collins,
A. D'Angelo,
A. Deur,
J. Fleming,
C. Hanretty,
T. Kageya,
M. Khandaker,
F. J. Klein,
E. Klempt,
V. Laine,
M. M. Lowry,
H. Lu,
C. Nepali,
V. A. Nikonov,
T. O'Connell,
A. M. Sandorfi,
A. V. Sarantsev,
R. A. Schumacher,
I. I. Strakovsky,
A. Švarc,
N. K. Walford,
X. Wei
, et al. (118 additional authors not shown)
Abstract:
We report the first beam-target double-polarization asymmetries in the $γ+ n(p) \rightarrow π^- + p(p)$ reaction spanning the nucleon resonance region from invariant mass $W$= $1500$ to $2300$ MeV. Circularly polarized photons and longitudinally polarized deuterons in $H\!D$ have been used with the CLAS detector at Jefferson Lab. The exclusive final state has been extracted using three very differ…
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We report the first beam-target double-polarization asymmetries in the $γ+ n(p) \rightarrow π^- + p(p)$ reaction spanning the nucleon resonance region from invariant mass $W$= $1500$ to $2300$ MeV. Circularly polarized photons and longitudinally polarized deuterons in $H\!D$ have been used with the CLAS detector at Jefferson Lab. The exclusive final state has been extracted using three very different analyses that show excellent agreement, and these have been used to deduce the {\it{E}} polarization observable for an effective neutron target. These results have been incorporated into new partial wave analyses, and have led to significant revisions for several $γnN^*$ resonance photo-couplings.
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Submitted 12 May, 2017;
originally announced May 2017.
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Analysis of the exclusive final state npe$^+$e$^-$ in quasi-free np reaction
Authors:
J. Adamczewski-Musch,
O. Arnold,
E. T. Atomssa,
C. Behnke,
A. Belounnas,
A. Belyaev,
J. C. Berger-Chen,
J. Biernat,
A. Blanco,
C. Blume,
M. Böhmer,
P. Bordalo,
S. Chernenko,
L. Chlad,
C. Deveaux,
J. Dreyer,
A. Dybczak,
E. Epple,
L. Fabbietti,
O. Fateev,
P. Filip,
P. Finocchiaro,
P. Fonte,
C. Franco,
J. Friese
, et al. (92 additional authors not shown)
Abstract:
We report on the investigation of dielectron production in tagged quasi-free neutron-proton collisions by using a deuteron beam of kinetic energy 1.25 GeV/u inpinging on a liquid hydrogen target. Our measurements with HADES confirm a significant excess of $e^+e^-$ pairs above the $π^{0}$ mass in the exclusive channel $dp \to npe^{+}e^{-}(p_{spect})$ as compared to the exclusive channel…
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We report on the investigation of dielectron production in tagged quasi-free neutron-proton collisions by using a deuteron beam of kinetic energy 1.25 GeV/u inpinging on a liquid hydrogen target. Our measurements with HADES confirm a significant excess of $e^+e^-$ pairs above the $π^{0}$ mass in the exclusive channel $dp \to npe^{+}e^{-}(p_{spect})$ as compared to the exclusive channel $ppe^{+}e^{-}$ measured in proton-proton collisions at the same energy. That excess points to different bremsstrahlung production mechanisms. Two models were evaluated for the role of the charged pion exchange between nucleons and double-$Δ$ excitation combined with intermediate $ρ$-meson production. Differential cross sections as a function of the $e^+e^-$ invariant mass and of the angles of the virtual photon, proton and electrons provide valuable constraints and encourage further investigations on both experimental and theoretical side.
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Submitted 24 March, 2017;
originally announced March 2017.
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Analysis of pion production data measured by HADES in proton-proton collisions at 1.25 GeV
Authors:
G. Agakishiev,
A. Balanda,
D. Belver,
A. Belyaev,
J. C. Berger-Chen,
A. Blanco,
M. Böhmer,
J. L. Boyard,
P. Cabanelas,
S. Chernenko,
A. Dybczak,
E. Epple,
L. Fabbietti,
O. Fateev,
P. Finocchiaro,
P. Fonte,
J. Friese,
I. Fröhlich,
T. Galatyuk,
J. A. Garzón,
R. Gernhäuser,
K. Göbel,
M. Golubeva,
D. González-Díaz,
F. Guber
, et al. (75 additional authors not shown)
Abstract:
Baryon resonance production in proton-proton collisions at a kinetic beam energy of 1.25 GeV is investigated. The multi-differential data were measured by the HADES collaboration. Exclusive channels with one pion in the final state ($npπ^{+}$ and $ppπ^{0}$) were put to extended studies based on various observables in the framework of a one-pion exchange model and with solutions obtained within the…
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Baryon resonance production in proton-proton collisions at a kinetic beam energy of 1.25 GeV is investigated. The multi-differential data were measured by the HADES collaboration. Exclusive channels with one pion in the final state ($npπ^{+}$ and $ppπ^{0}$) were put to extended studies based on various observables in the framework of a one-pion exchange model and with solutions obtained within the framework of a partial wave analysis (PWA) of the Bonn-Gatchina group. The results of the PWA confirm the dominant contribution of the $Δ$(1232), yet with a sizable impact of the $N$(1440) and non-resonant partial waves.
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Submitted 24 March, 2017;
originally announced March 2017.
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$Δ$(1232) Dalitz decay in proton-proton collisions at T=1.25 GeV measured with HADES
Authors:
J. Adamczewski-Musch,
O. Arnold,
E. T. Atomssa,
C. Behnke,
A. Belounnas,
A. Belyaev,
J. C. Berger-Chen,
J. Biernat,
A. Blanco,
C. Blume,
M. Böhmer,
P. Bordalo,
S. Chernenko,
L. Chlad,
C. Deveaux,
J. Dreyer,
A. Dybczak,
E. Epple,
L. Fabbietti,
O. Fateev,
P. Filip,
P. Finocchiaro,
P. Fonte,
C. Franco,
J. Friese
, et al. (92 additional authors not shown)
Abstract:
We report on the investigation of $Δ$(1232) production and decay in proton-proton collisions at a kinetic energy of 1.25 GeV measured with HADES. Exclusive dilepton decay channels $ppe^{+}e^{-}$ and $ppe^{+}e^{-}γ$ have been studied and compared with the partial wave analysis of the hadronic $ppπ^{0}$ channel. They allow to access both $Δ^+ \to pπ^0(e^+e^-γ)$ and $Δ^+ \to pe^+e^-$ Dalitz decay cha…
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We report on the investigation of $Δ$(1232) production and decay in proton-proton collisions at a kinetic energy of 1.25 GeV measured with HADES. Exclusive dilepton decay channels $ppe^{+}e^{-}$ and $ppe^{+}e^{-}γ$ have been studied and compared with the partial wave analysis of the hadronic $ppπ^{0}$ channel. They allow to access both $Δ^+ \to pπ^0(e^+e^-γ)$ and $Δ^+ \to pe^+e^-$ Dalitz decay channels. The perfect reconstruction of the well known $π^0$ Dalitz decay serves as a proof of the consistency of the analysis. The $Δ$ Dalitz decay is identified for the first time and the sensitivity to N-$Δ$ transition form factors is tested. The $Δ$(1232) Dalitz decay branching ratio is also determined for the first time; our result is (4.19 $\pm$ 0.62 syst. $\pm$ 0.34 stat.) $\times $ 10$^{-5}$, albeit with some model dependence.
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Submitted 24 March, 2017; v1 submitted 22 March, 2017;
originally announced March 2017.
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Study of the proton-proton collisions at 1683 MeV/c
Authors:
K. N. Ermakov,
V. A. Nikonov,
O. V. Rogachevsky,
A. V. Sarantsev,
V. V. Sarantsev,
S. G. Sherman
Abstract:
The new data on the elastic $pp$ and single pion production reaction $pp\to pn π^{+}$ taken at the incident proton momentum 1683 MeV/c are presented. The data on the $pp\to pn π^{+}$ reaction are compared with predictions from the OPE model. To extract contributions of the leading partial waves the single pion production data are analyzed in the framework of the event-by-event maximum likelihood m…
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The new data on the elastic $pp$ and single pion production reaction $pp\to pn π^{+}$ taken at the incident proton momentum 1683 MeV/c are presented. The data on the $pp\to pn π^{+}$ reaction are compared with predictions from the OPE model. To extract contributions of the leading partial waves the single pion production data are analyzed in the framework of the event-by-event maximum likelihood method together with the data measured earlier. The analysis allows us to obtain the assessment with a better precision the contributions from different initial partial waves.
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Submitted 28 April, 2017; v1 submitted 17 February, 2017;
originally announced February 2017.
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Is there a narrow $N(1685)$?
Authors:
A. V. Anisovich,
V. Burkert,
E. Klempt,
V. A. Nikonov,
A. V. Sarantsev,
U. Thoma
Abstract:
The helicity-dependent observable $E$ for the reaction $γd\to ηn (p)$ with a spectator proton was recently measured by the A2 Collaboration at MAMI in Mainz. The data were interpreted as further evidence for a narrow resonance with spin and parity $J^P=1/2^+$ ($P_{11}$ wave). However, a full partial wave analysis without any narrow resonance leads to an excellent description of the data, imposing…
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The helicity-dependent observable $E$ for the reaction $γd\to ηn (p)$ with a spectator proton was recently measured by the A2 Collaboration at MAMI in Mainz. The data were interpreted as further evidence for a narrow resonance with spin and parity $J^P=1/2^+$ ($P_{11}$ wave). However, a full partial wave analysis without any narrow resonance leads to an excellent description of the data, imposing a narrow resonance with the properties suggested by the A2 Collaboration leads to a significant deterioration of the fit quality: there is no need for a narrow resonance.
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Submitted 28 January, 2017; v1 submitted 23 January, 2017;
originally announced January 2017.
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Vertex operators for production of baryon resonances in nucleon-gamma collisions with preserving gauge invariance and analyticity
Authors:
A. V. Anisovich,
V. V. Anisovich,
A. V. Sarantsev
Abstract:
Vertex operators for photo- and electro-production of baryon states with arbitrary spin-parity, $ γ+ N\to B(J^P)$, are constructed. The operators obey gauge invariance and analyticity constraints. Analyticity is realized as a requirement of the generalized Siegert theorem for vertex form factors.
Vertex operators for photo- and electro-production of baryon states with arbitrary spin-parity, $ γ+ N\to B(J^P)$, are constructed. The operators obey gauge invariance and analyticity constraints. Analyticity is realized as a requirement of the generalized Siegert theorem for vertex form factors.
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Submitted 22 September, 2016;
originally announced September 2016.
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Propagators of resonances and rescatterings of the decay products
Authors:
A. V. Anisovich,
V. V. Anisovich,
M. A. Matveev,
A. V. Sarantsev,
A. N. Semenova,
J. Nyiri
Abstract:
Hadronic resonance propagators which take into account the analytical properties of decay processes are built in terms of the dispersion relation technique. Such propagators can describe multi-component systems, for example, those when quark degrees of freedom create a resonance state, and decay products correct the corresponding pole by adding hadronic deuteron-like components. Meson and baryon s…
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Hadronic resonance propagators which take into account the analytical properties of decay processes are built in terms of the dispersion relation technique. Such propagators can describe multi-component systems, for example, those when quark degrees of freedom create a resonance state, and decay products correct the corresponding pole by adding hadronic deuteron-like components. Meson and baryon states are considered, examples of particles with different spins are presented.
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Submitted 9 August, 2016; v1 submitted 21 May, 2016;
originally announced May 2016.
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$N^{\bf *}$ decays to $Nω$ from new data on $γp\to ωp$
Authors:
I. Denisenko,
A. V. Anisovich,
V. Crede,
H. Eberhardt,
E. Klempt,
V. A. Nikonov,
A. V. Sarantsev,
H. Schmieden,
U. Thoma,
A. Wilson
Abstract:
Data on the reaction $γp\to ωp$ with $ω\toπ^0γ$, taken with unpolarized or polarized beams in combination with an unpolarized or polarized proton-target, were analyzed within the Bonn-Gatchina (BnGa) partial wave analysis. Differential cross sections, several spin density matrix elements, the beam asymmetry $Σ$, the normalized helicity difference $E$, and the correlation $G$ between linear photon…
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Data on the reaction $γp\to ωp$ with $ω\toπ^0γ$, taken with unpolarized or polarized beams in combination with an unpolarized or polarized proton-target, were analyzed within the Bonn-Gatchina (BnGa) partial wave analysis. Differential cross sections, several spin density matrix elements, the beam asymmetry $Σ$, the normalized helicity difference $E$, and the correlation $G$ between linear photon and longitudinal target polarization were included in a large data base on pion and photo-induced reactions. The data on $ω$ photoproduction are used to determine twelve $N^*\to Nω$ branching ratios; most of these are determined for the first time.
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Submitted 22 January, 2016;
originally announced January 2016.
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Non-strange and strange pentaquarks with hidden charm
Authors:
V. V. Anisovich,
M. A. Matveev,
J. Nyiri,
A. V. Sarantsev,
A. N. Semenova
Abstract:
Non-strange and strange pentaquaks with hidden charm are considered as diquark-diquark-antiquark composite systems. Spin and isospin content of such exotic states is discussed and masses are evaluated.
Non-strange and strange pentaquaks with hidden charm are considered as diquark-diquark-antiquark composite systems. Spin and isospin content of such exotic states is discussed and masses are evaluated.
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Submitted 16 September, 2015;
originally announced September 2015.
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Pentaquarks and strange tetraquark mesons
Authors:
V. V. Anisovich,
M. A. Matveev,
A. V. Sarantsev,
A. N. Semenova
Abstract:
We consider the interplay of the pentaquark states and strange tetraquark states in the decay $Λ^0_b\to K^-J/ψp$. Possible existence of ($cs\bar c\bar u$)-states is taken up and their manifestation in the $K^-J/ψ$-channel is discussed. It is emphasised that these exotic mesons can imitate broad bumps in the in the $pJ/ψ$-channel.
We consider the interplay of the pentaquark states and strange tetraquark states in the decay $Λ^0_b\to K^-J/ψp$. Possible existence of ($cs\bar c\bar u$)-states is taken up and their manifestation in the $K^-J/ψ$-channel is discussed. It is emphasised that these exotic mesons can imitate broad bumps in the in the $pJ/ψ$-channel.
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Submitted 16 September, 2015; v1 submitted 10 September, 2015;
originally announced September 2015.
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Photoproduction of ω Mesons off the Proton
Authors:
A. Wilson,
V. Crede,
A. V. Anisovich,
J. C. S. Bacelar,
B. Bantes,
O. Bartholomy,
D. Bayadilov,
R. Beck,
Y. A. Beloglazov,
K. T. Brinkmann,
R. Castelijns,
H. Dutz,
D. Elsner,
R. Ewald,
F. Frommberger,
M. Fuchs,
Chr. Funke,
R. Gregor,
A. Gridnev,
E. Gutz,
J. Hannappel,
W. Hillert,
P. Hoffmeister,
I. Horn,
I. Jaegle
, et al. (40 additional authors not shown)
Abstract:
The differential cross sections and unpolarized spin-density matrix elements for the reaction $γp\to pω$ were measured using the CBELSA/TAPS experiment for initial photon energies ranging from the reaction threshold to 2.5 GeV. These observables were measured from the radiative decay of the $ω$ meson, $ω\toπ^0γ$. The cross sections cover the full angular range and show the full extent of the $t$-c…
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The differential cross sections and unpolarized spin-density matrix elements for the reaction $γp\to pω$ were measured using the CBELSA/TAPS experiment for initial photon energies ranging from the reaction threshold to 2.5 GeV. These observables were measured from the radiative decay of the $ω$ meson, $ω\toπ^0γ$. The cross sections cover the full angular range and show the full extent of the $t$-channel forward rise. The overall shape of the angular distributions in the differential cross sections and unpolarized spin-density matrix elements are in fair agreement with previous data. In addition, for the first time, a beam of linearly-polarized tagged photons in the energy range from 1150 MeV to 1650 MeV was used to extract polarized spin-density matrix elements.
These data were included in the Bonn-Gatchina partial wave analysis (PWA). The dominant contribution to $ω$ photoproduction near threshold was found to be the $3/2^+$ partial wave, which is primarily due to the sub-threshold $N(1720)\,3/2^+$ resonance. At higher energies, pomeron-exchange was found to dominate whereas $π$-exchange remained small. These $t$-channel contributions as well as further contributions from nucleon resonances were necessary to describe the entire dataset: the $1/2^-$, $3/2^-$, and $5/2^+$ partial waves were also found to contribute significantly.
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Submitted 6 August, 2015;
originally announced August 2015.
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Pentaquarks and resonances in the $pJ/ψ$ spectrum
Authors:
V. V. Anisovich,
M. A. Matveev,
J. Nyiri,
A. V. Sarantsev,
A. N. Semenova
Abstract:
We consider exotic baryons with hidden charm as antiquark-diquark-diquark composite systems. Spin and isospin structure of such exotic states is given and masses are estimated. The data for production of pentaquarks in the reaction $Λ_b\to K^-p J/ψ$ are discussed. We suggest that the narrow peak in $pJ/ψ$ spectra at 4450 MeV is antiquark-diquark-diquark state with negative parity, $5/2^{-}(4450)$,…
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We consider exotic baryons with hidden charm as antiquark-diquark-diquark composite systems. Spin and isospin structure of such exotic states is given and masses are estimated. The data for production of pentaquarks in the reaction $Λ_b\to K^-p J/ψ$ are discussed. We suggest that the narrow peak in $pJ/ψ$ spectra at 4450 MeV is antiquark-diquark-diquark state with negative parity, $5/2^{-}(4450)$, while the broad bump $3/2^{+}(4380)$ is the result of rescatterings in the ($pJ/ψ$)-channel. Positions of other pentaquarks with negative parity are estimated.
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Submitted 28 July, 2015;
originally announced July 2015.
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Exotic mesons with hidden charm as diquark-antidiquark states
Authors:
V. V. Anisovich,
M. A. Matveev,
A. V. Sarantsev,
A. N. Semenova
Abstract:
Exotic mesons with hidden strange ($s\bar s$) and heavy quark pairs ($Q\bar Q$), where $Q=c,b$, are considered as diquark-antidiquark systems, $(Qs)(\bar Q\bar s)$. Taking into account that these states can recombinate into two-meson ones, we study the interplay of these states in terms of the dispersion relation D-function technique. The classification of exotic mesons is discussed, coefficients…
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Exotic mesons with hidden strange ($s\bar s$) and heavy quark pairs ($Q\bar Q$), where $Q=c,b$, are considered as diquark-antidiquark systems, $(Qs)(\bar Q\bar s)$. Taking into account that these states can recombinate into two-meson ones, we study the interplay of these states in terms of the dispersion relation D-function technique. The classification of exotic mesons is discussed, coefficients for decay modes are given, predictions for new states are presented. The nonet structure for $((Qq)(\bar Q \bar q)$, ($(Qs)(\bar Q\bar s$)), ($(Qq)(\bar Q\bar s))$- states ($q=u,d$) is suggested.
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Submitted 26 July, 2015;
originally announced July 2015.
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High statistics study of the reaction $γp\to p\;2π^0$
Authors:
V. Sokhoyan,
E. Gutz,
V. Crede,
H. van Pee,
A. V. Anisovich,
J. C. S. Bacelar,
B. Bantes,
O. Bartholomy,
D. Bayadilov,
R. Beck,
Y. A. Beloglazov,
R. Castelijns,
H. Dutz,
D. Elsner,
R. Ewald,
F. Frommberger,
M. Fuchs,
Ch. Funke,
R. Gregor,
A. B. Gridnev,
W. Hillert,
Ph. Hoffmeister,
I. Horn,
I. Jaegle,
J. Junkersfeld
, et al. (40 additional authors not shown)
Abstract:
The photoproduction of 2$π^0$ mesons off protons was studied with the Crystal Barrel/TAPS experiment at the electron accelerator ELSA in Bonn. The energy of photons produced in a radiator was tagged in the energy range from 600\,MeV to 2.5\,GeV. Differential and total cross sections and $pπ^0π^0$ Dalitz plots are presented. Part of the data was taken with a diamond radiator producing linearly pola…
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The photoproduction of 2$π^0$ mesons off protons was studied with the Crystal Barrel/TAPS experiment at the electron accelerator ELSA in Bonn. The energy of photons produced in a radiator was tagged in the energy range from 600\,MeV to 2.5\,GeV. Differential and total cross sections and $pπ^0π^0$ Dalitz plots are presented. Part of the data was taken with a diamond radiator producing linearly polarized photons, and beam asymmetries were derived. Properties of nucleon and $Δ$ resonances contributing to the $pπ^0π^0$ final state were determined within the BnGa partial wave analysis. The data presented here allow us to determine branching ratios of nucleon and $Δ$ resonances for their decays into $pπ^0π^0$ via several intermediate states. Most prominent are decays proceeding via $Δ(1232)π$, $N(1440)1/2^+π$, $N(1520)3/2^-π$, $N(1680)5/2^+π$, but also $pf_0(500)$, $pf_0(980)$, and $pf_2(1270)$ contribute to the reaction.
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Submitted 3 December, 2015; v1 submitted 9 July, 2015;
originally announced July 2015.
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Evidence for $Δ(2200)7/2^-$ from photoproduction and consequence for chiral-symmetry restoration at high mass
Authors:
A. V. Anisovich,
V. Burkert,
J. Hartmann,
E. Klempt,
V. A. Nikonov,
E. Pasyuk,
A. V. Sarantsev,
S. Strauch,
U. Thoma
Abstract:
We report a partial-wave analysis of new data on the double-polarization variable $E$ for the reactions $γp\to π^+ n$ and $γp\to π^0 p$ and of further data published earlier. The analysis within the Bonn-Gatchina (BnGa) formalism reveals evidence for a poorly known baryon resonance, the one-star $Δ(2200)7/2^-$. This is the lowest-mass $Δ^*$ resonance with spin-parity $J^P=7/2^-$. Its mass is signi…
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We report a partial-wave analysis of new data on the double-polarization variable $E$ for the reactions $γp\to π^+ n$ and $γp\to π^0 p$ and of further data published earlier. The analysis within the Bonn-Gatchina (BnGa) formalism reveals evidence for a poorly known baryon resonance, the one-star $Δ(2200)7/2^-$. This is the lowest-mass $Δ^*$ resonance with spin-parity $J^P=7/2^-$. Its mass is significantly higher than the mass of its parity partner $Δ(1950)7/2^+$ which is the lowest-mass $Δ^*$ resonance with spin-parity $J^P=7/2^+$. It has been suggested that chiral symmetry might be restored in the high-mass region of hadron excitations, and that these two resonances should be degenerate in mass. Our findings are in conflict with this prediction.
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Submitted 21 February, 2017; v1 submitted 19 March, 2015;
originally announced March 2015.
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First Measurement of the Polarization Observable E in the $\vec p(\vec γ,π^+)n$ Reaction up to 2.25 GeV
Authors:
S. Strauch,
W. J. Briscoe,
M. Döring,
E. Klempt,
V. A. Nikonov,
E. Pasyuk,
D. Rönchen,
A. V. Sarantsev,
I. Strakovsky,
R. Workman,
K. P. Adhikari,
D. Adikaram,
M. D. Anderson,
S. Anefalos Pereira,
A. V. Anisovich,
R. A. Badui,
J. Ball,
V. Batourine,
M. Battaglieri,
I. Bedlinskiy,
N. Benmouna,
A. S. Biselli,
J. Brock,
W. K. Brooks,
V. D. Burkert
, et al. (143 additional authors not shown)
Abstract:
First results from the longitudinally polarized frozen-spin target (FROST) program are reported. The double-polarization observable E, for the reaction $\vec γ\vec p \to π^+n$, has been measured using a circularly polarized tagged-photon beam, with energies from 0.35 to 2.37 GeV. The final-state pions were detected with the CEBAF Large Acceptance Spectrometer in Hall B at the Thomas Jefferson Nati…
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First results from the longitudinally polarized frozen-spin target (FROST) program are reported. The double-polarization observable E, for the reaction $\vec γ\vec p \to π^+n$, has been measured using a circularly polarized tagged-photon beam, with energies from 0.35 to 2.37 GeV. The final-state pions were detected with the CEBAF Large Acceptance Spectrometer in Hall B at the Thomas Jefferson National Accelerator Facility. These polarization data agree fairly well with previous partial-wave analyses at low photon energies. Over much of the covered energy range, however, significant deviations are observed, particularly in the high-energy region where high-L multipoles contribute. The data have been included in new multipole analyses resulting in updated nucleon resonance parameters. We report updated fits from the Bonn-Gatchina, Jülich, and SAID groups.
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Submitted 17 March, 2015;
originally announced March 2015.
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Interference phenomena in the $J^P=1/2^-$-wave in $η$ photoproduction
Authors:
A. V. Anisovich,
E. Klempt,
B. Krusche,
V. A. Nikonov,
A. V. Sarantsev,
U. Thoma,
D. Werthmüller
Abstract:
The recent precise experimental results for the photoproduction of $η$-mesons off the neutron measured with the Crystal Ball/TAPS calorimeter at the MAMI accelerator have been investigated in detail in the framework of the Bonn-Gatchina coupled channel model. The main result is that the narrow structure observed in the excitation function of $γn \rightarrow nη$ can be reproduced fully with a parti…
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The recent precise experimental results for the photoproduction of $η$-mesons off the neutron measured with the Crystal Ball/TAPS calorimeter at the MAMI accelerator have been investigated in detail in the framework of the Bonn-Gatchina coupled channel model. The main result is that the narrow structure observed in the excitation function of $γn \rightarrow nη$ can be reproduced fully with a particular interference pattern in the $J^P=1/2^-$ partial wave. Introduction of the narrow resonance $N(1685)$ with the properties reported in earlier publications deteriorates the quality of the fit.
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Submitted 1 June, 2015; v1 submitted 9 January, 2015;
originally announced January 2015.
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Analysis Tools for Next-Generation Hadron Spectroscopy Experiments
Authors:
M. Battaglieri,
B. J. Briscoe,
A. Celentano,
S. -U. Chung,
A. D'Angelo,
R. De Vita,
M. Döring,
J. Dudek,
S. Eidelman,
S. Fegan,
J. Ferretti,
A. Filippi,
G. Fox,
G. Galata,
H. Garcia-Tecocoatzi,
D. I. Glazier,
B. Grube,
C. Hanhart,
M. Hoferichter,
S. M. Hughes,
D. G. Ireland,
B. Ketzer,
F. J. Klein,
B. Kubis,
B. Liu
, et al. (22 additional authors not shown)
Abstract:
The series of workshops on New Partial-Wave Analysis Tools for Next-Generation Hadron Spectroscopy Experiments was initiated with the ATHOS 2012 meeting, which took place in Camogli, Italy, June 20-22, 2012. It was followed by ATHOS 2013 in Kloster Seeon near Munich, Germany, May 21-24, 2013. The third, ATHOS3, meeting is planned for April 13-17, 2015 at The George Washington University Virginia S…
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The series of workshops on New Partial-Wave Analysis Tools for Next-Generation Hadron Spectroscopy Experiments was initiated with the ATHOS 2012 meeting, which took place in Camogli, Italy, June 20-22, 2012. It was followed by ATHOS 2013 in Kloster Seeon near Munich, Germany, May 21-24, 2013. The third, ATHOS3, meeting is planned for April 13-17, 2015 at The George Washington University Virginia Science and Technology Campus, USA. The workshops focus on the development of amplitude analysis tools for meson and baryon spectroscopy, and complement other programs in hadron spectroscopy organized in the recent past including the INT-JLab Workshop on Hadron Spectroscopy in Seattle in 2009, the International Workshop on Amplitude Analysis in Hadron Spectroscopy at the ECT*-Trento in 2011, the School on Amplitude Analysis in Modern Physics in Bad Honnef in 2011, the Jefferson Lab Advanced Study Institute Summer School in 2012, and the School on Concepts of Modern Amplitude Analysis Techniques in Flecken-Zechlin near Berlin in September 2013. The aim of this document is to summarize the discussions that took place at the ATHOS 2012 and ATHOS 2013 meetings. We do not attempt a comprehensive review of the field of amplitude analysis, but offer a collection of thoughts that we hope may lay the ground for such a document.
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Submitted 30 March, 2015; v1 submitted 19 December, 2014;
originally announced December 2014.
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Status of some P-wave baryon resonances and importance of inelastic channels
Authors:
Volker D. Burkert,
Hiroyuki Kamano,
Eberhard Klempt,
Deborah Ronchen,
Andrey V. Sarantsev,
Toru Sato,
Alfred Svarc,
Lothar Tiator,
Ron L. Workman
Abstract:
We analyze the current status of three P-wave baryon states $N(1710){1/ 2}^+$, $N(1900){3/2}^+$, and $Δ(1600){3/2}^+$ as given in the Review of Particles Physics (RPP). Since the evidence for a particle's existence is linked to its RPP "star" rating, we discuss its subjective present definition. We also present the accumulating evidence supporting these states and give our new "star" rating recomm…
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We analyze the current status of three P-wave baryon states $N(1710){1/ 2}^+$, $N(1900){3/2}^+$, and $Δ(1600){3/2}^+$ as given in the Review of Particles Physics (RPP). Since the evidence for a particle's existence is linked to its RPP "star" rating, we discuss its subjective present definition. We also present the accumulating evidence supporting these states and give our new "star" rating recommendations.
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Submitted 30 November, 2014;
originally announced December 2014.
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Partial Wave Analysis of the Reaction $p(3.5 GeV)+p \to pK^+Λ$ to Search for the "$ppK^-$" Bound State
Authors:
G. Agakishiev,
O. Arnold,
D. Belver,
A. Belyaev,
J. C. Berger-Chen,
A. Blanco,
M. Böhmer,
J. L. Boyard,
P. Cabanelas,
S. Chernenko,
A. Dybczak,
E. Epple,
L. Fabbietti,
O. Fateev,
P. Finocchiaro,
P. Fonte,
J. Friese,
I. Fröhlich,
T. Galatyuk,
J. A. Garzón,
R. Gernhäuser,
K. Göbel,
M. Golubeva,
D. González-Díaz,
F. Guber
, et al. (71 additional authors not shown)
Abstract:
Employing the Bonn-Gatchina partial wave analysis framework (PWA), we have analyzed HADES data of the reaction $p(3.5GeV)+p\to pK^{+}Λ$. This reaction might contain information about the kaonic cluster "$ppK^-$" via its decay into $pΛ$. Due to interference effects in our coherent description of the data, a hypothetical $\overline{K}NN$ (or, specifically "$ppK^-$") cluster signal must not necessari…
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Employing the Bonn-Gatchina partial wave analysis framework (PWA), we have analyzed HADES data of the reaction $p(3.5GeV)+p\to pK^{+}Λ$. This reaction might contain information about the kaonic cluster "$ppK^-$" via its decay into $pΛ$. Due to interference effects in our coherent description of the data, a hypothetical $\overline{K}NN$ (or, specifically "$ppK^-$") cluster signal must not necessarily show up as a pronounced feature (e.g. a peak) in an invariant mass spectra like $pΛ$. Our PWA analysis includes a variety of resonant and non-resonant intermediate states and delivers a good description of our data (various angular distributions and two-hadron invariant mass spectra) without a contribution of a $\overline{K}NN$ cluster. At a confidence level of CL$_{s}$=95\% such a cluster can not contribute more than 2-12\% to the total cross section with a $pK^{+}Λ$ final state, which translates into a production cross-section between 0.7 $μb$ and 4.2 $μb$, respectively. The range of the upper limit depends on the assumed cluster mass, width and production process.
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Submitted 29 October, 2014;
originally announced October 2014.