The ϱ radiative decay width: A measurement at 200 GeV

Capraro, L.; Levy, P.; Querrou, M.; Hecke, Bruno Van; Verbeken, M.; Enorini, E.; Fabbri, F. L.; Laurelli, P.; Zallo, A.; Bellini, G.; Bonetti, S.; Fincato, A.; Leopold, Matthew; Menasce, D.; Meroni, E.; Moroni, L.; Pedrini, D.; Perasso, L.; Ragusa, F.; Sala, Simone; Vittone, M.; Amendolla, S.R.; Batignani, G.; Bedeschi, A.; Bellamy, E.H.; Bertolucci, E.; Bosisio, L.; Bottigli, U.; Bradaschia, C.; Fidecaro, F.; Foà, L.; Focardi, E.; Giannetti, P.; Giorgi, M. A.; Marrocchesi, P. S.; Menzione, A.; Ristori, L.; Scribano, A.; Stefanini, A.; Tonelli, G.; Beck, G.A.; Bologna, G.; Green, M.G.; March, P.V.; Landon, M. P. J.; Strong, J. A.; Тенчини, Р.

doi:10.1016/0550-3213(87)90233-1

Cited by 35 publications

(24 citation statements)

References 9 publications

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“…Comparing to the expression given in Ref. [63], where the cm energy E ππ has been approximated by the real part of the ρ mass, we find a definition of the radiative decay width of ρ + → π + γ in terms of the form factor,…”

Section: Appendix C: Symmetry Factor and Identical Particlesmentioning

confidence: 86%

“…[46] for a heavier quark mass, where the ρ is stable (green). Also shown is the experimentally determined value for the ρπ photocoupling [62,63].…”

Section: Fig 13mentioning

confidence: 99%

“…Figure 13 also shows (in green) the form factor of the ρ computed with a heavier light quark mass such that the pion has mass ∼ 700 MeV and the ρ is a stable hadron [46]. We also compare to experimental estimates of the real part of the ρπ photocoupling [62,63]. In Eq.…”

Section: Fig 13mentioning

confidence: 99%

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ππ→πγamplitude and the resonantρ→πγtransition from lattice QCD

et al. 2016

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We present a determination of the P -wave ππ → πγ transition amplitude from lattice quantum chromodynamics. Matrix elements of the vector current in a finite-volume are extracted from three-point correlation functions, and from these we determine the infinite-volume amplitude using a generalization of the Lellouch-Lüscher formalism. We determine the amplitude for a range of discrete values of the ππ energy and virtuality of the photon, and observe the expected dynamical enhancement due to the ρ resonance. Describing the energy dependence of the amplitude, we are able to analytically continue into the complex energy plane and from the residue at the ρ pole extract the ρ → πγ transition form factor. This calculation, at mπ ≈ 400 MeV, is the first to determine the form factor of an unstable hadron within a first principles approach to QCD.

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Section: Appendix C: Symmetry Factor and Identical Particlesmentioning

confidence: 86%

“…[46] for a heavier quark mass, where the ρ is stable (green). Also shown is the experimentally determined value for the ρπ photocoupling [62,63].…”

Section: Fig 13mentioning

confidence: 99%

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ππ→πγamplitude and the resonantρ→πγtransition from lattice QCD

et al. 2016

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“…We include the PDG average [1] as well as the three experimental measurements [37][38][39] used in its evaluation. For the quark model, the choice of normalisation used in Ref.…”

Section: Resultsmentioning

confidence: 99%

Transition ofρ→πγin lattice QCD

et al. 2015

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With the ongoing experimental interest in exploring the excited hadron spectrum, evaluations of the matrix elements describing the formation and decay of such states via radiative processes provide us with an important connection between theory and experiment. In particular, determinations obtained via the lattice allow for a direct comparison of QCD-expectation with experimental observation. Here we present the first light quark determination of the ρ → πγ transition form factor from lattice QCD using dynamical quarks. Using the PACS-CS 2+1 flavour QCD ensembles we are able to obtain results across a range of masses, to the near physical value of mπ = 157 MeV. An important aspect of our approach is the use of variational methods to isolate the desired QCD eigenstate. For low-lying states, such techniques facilitate the removal of excited state contributions. In principle the method enables one to consider arbitrary eigenstates. We find our results are in accord with the non-relativistic quark model for heavy masses. In moving towards the light-quark regime we observe an interesting quark mass dependence, contrary to the quark model expectation. Comparison of our light-quark result with experimental determinations highlights a significant discrepancy suggesting that disconnected sea-quark loop contributions may play a significant role in fully describing this process.

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“…Currently available information on the radiative coupling of the ρ(770) [6] largely derives from the highmomentum Primakoff experiments [57][58][59], while no experimental result is available for the ρ 3 (1690) at all. Thanks to its high-statistics data, COMPASS has the unique opportunity to determine these couplings either for the first time or with unprecedented accuracy; compare their results for the radiative widths of the a 2 (1320) and the π 2 (1670) as extracted from the similar Primakoff reaction γπ → 3π [60].…”

Section: Line Shape Of γπ → ππmentioning

confidence: 99%

Radiative resonance couplings in γπ→ππ

2017

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Studies of the reaction γπ → ππ, in the context of the ongoing Primakoff program of the COM-PASS experiment at CERN, give access to the radiative couplings of the ρ(770) and ρ3(1690) resonances. We provide a vector-meson-dominance estimate of the respective radiative width of the ρ3, Γρ 3 →πγ = 48(18) keV, as well as its impact on the F -wave in γπ → ππ. For the ρ(770), we establish the formalism necessary to extract its radiative coupling directly from the residue of the resonance pole by analytic continuation of the γπ → ππ amplitude to the second Riemann sheet, without any reference to the vector-meson-dominance hypothesis.

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The ϱ radiative decay width: A measurement at 200 GeV

Cited by 35 publications

References 9 publications

ππ→πγamplitude and the resonantρ→πγtransition from lattice QCD

ππ→πγamplitude and the resonantρ→πγtransition from lattice QCD

Transition ofρ→πγin lattice QCD

Radiative resonance couplings in γπ→ππ

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The ϱ radiative decay width: A measurement at 200 GeV

Cited by 35 publications

References 9 publications

ππ→πγ*amplitude and the resonantρ→πγ*transition from lattice QCD

ππ→πγ*amplitude and the resonantρ→πγ*transition from lattice QCD

Transition ofρ→πγin lattice QCD

Radiative resonance couplings in γπ→ππ

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Product

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ππ→πγamplitude and the resonantρ→πγtransition from lattice QCD

ππ→πγamplitude and the resonantρ→πγtransition from lattice QCD