Analysis of the $${\psi (3770)}$$ ψ ( 3770 ) resonance in line with unitarity and analyticity constraints

Christoph Hanhart (Institute for Advanced Simulation and Institut für Kernphysik, Forschungszentrum Jülich, Jülich, 52425, Germany) ; Stephan Kürten (Physik Department T31, Technische Universität München, Garching, 85748, Germany; Helmholtz-Institut für Strahlen- und Kernphysik (Theorie), Bethe Center for Theoretical Physics, Universität Bonn, Bonn, 53115, Germany) ; Méril Reboud (Theoretische Physik 1, Naturwissenschaftlich-Technische Fakultät, Universität Siegen, Siegen, 57068, Germany) ; Danny Dyk (Institute for Particle Physics Phenomenology and Department of Physics, Durham University, DH1 3LE, Durham, UK)

We study the inclusive and exclusive cross sections of $$e^+e^-\rightarrow \text {hadrons}$$ e + e - hadrons for center-of-mass energies between 3.70 and $$3.83\,\,\textrm{GeV} $$ 3.83 GeV to infer the mass, width, and couplings of the $$\psi (3770)$$ ψ ( 3770 ) resonance. By using a coupled-channel K-matrix approach, we setup our analysis to respect unitarity and the analyticity properties of the underlying scattering amplitudes. We fit several models to the full dataset and identify our nominal results through a statistical model comparison. We find that, accounting for the interplay between the $$\psi (2S)$$ ψ ( 2 S ) and the $$\psi (3770)$$ ψ ( 3770 ) , no further pole is required to describe the $$\psi (3770)$$ ψ ( 3770 ) line shape. In particular we derive from the pole location $$M_{\psi (3770)}~=~3778.8~\pm ~0.3~\,\textrm{MeV} $$ M ψ ( 3770 ) = 3778.8 ± 0.3 MeV and $$\varGamma _{\psi (3770)}~=~25.0~\pm ~0.5~\,\textrm{MeV} $$ Γ ψ ( 3770 ) = 25.0 ± 0.5 MeV . Moreover, we find the decay to $$D^+D^-$$ D + D - and $$D^0\bar{D}^0$$ D 0 D ¯ 0 to be consistent with isospin symmetry and derive an upper bound on the branching ratio $${\mathcal {B}}(\psi (3770) \rightarrow \text {non-}D\bar{D}) < 6\%$$ B ( ψ ( 3770 ) non- D D ¯ ) < 6 % at $$90\%$$ 90 % probability.

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      "title": "Analysis of the  $${\\psi (3770)}$$  <math> <mrow> <mi>\u03c8</mi> <mo>(</mo> <mn>3770</mn> <mo>)</mo> </mrow> </math>   resonance in line with unitarity and analyticity constraints"
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      "source": "Springer", 
      "value": "We study the inclusive and exclusive cross sections of  $$e^+e^-\\rightarrow \\text {hadrons}$$  <math> <mrow> <msup> <mi>e</mi> <mo>+</mo> </msup> <msup> <mi>e</mi> <mo>-</mo> </msup> <mo>\u2192</mo> <mtext>hadrons</mtext> </mrow> </math>   for center-of-mass energies between 3.70 and  $$3.83\\,\\,\\textrm{GeV} $$  <math> <mrow> <mn>3.83</mn> <mspace width=\"0.166667em\"></mspace> <mspace width=\"0.166667em\"></mspace> <mtext>GeV</mtext> </mrow> </math>   to infer the mass, width, and couplings of the  $$\\psi (3770)$$  <math> <mrow> <mi>\u03c8</mi> <mo>(</mo> <mn>3770</mn> <mo>)</mo> </mrow> </math>   resonance. By using a coupled-channel K-matrix approach, we setup our analysis to respect unitarity and the analyticity properties of the underlying scattering amplitudes. We fit several models to the full dataset and identify our nominal results through a statistical model comparison. We find that, accounting for the interplay between the  $$\\psi (2S)$$  <math> <mrow> <mi>\u03c8</mi> <mo>(</mo> <mn>2</mn> <mi>S</mi> <mo>)</mo> </mrow> </math>   and the  $$\\psi (3770)$$  <math> <mrow> <mi>\u03c8</mi> <mo>(</mo> <mn>3770</mn> <mo>)</mo> </mrow> </math>  , no further pole is required to describe the  $$\\psi (3770)$$  <math> <mrow> <mi>\u03c8</mi> <mo>(</mo> <mn>3770</mn> <mo>)</mo> </mrow> </math>   line shape. In particular we derive from the pole location  $$M_{\\psi (3770)}~=~3778.8~\\pm ~0.3~\\,\\textrm{MeV} $$  <math> <mrow> <msub> <mi>M</mi> <mrow> <mi>\u03c8</mi> <mo>(</mo> <mn>3770</mn> <mo>)</mo> </mrow> </msub> <mspace width=\"3.33333pt\"></mspace> <mo>=</mo> <mspace width=\"3.33333pt\"></mspace> <mn>3778.8</mn> <mspace width=\"3.33333pt\"></mspace> <mo>\u00b1</mo> <mspace width=\"3.33333pt\"></mspace> <mn>0.3</mn> <mspace width=\"3.33333pt\"></mspace> <mspace width=\"0.166667em\"></mspace> <mtext>MeV</mtext> </mrow> </math>   and  $$\\varGamma _{\\psi (3770)}~=~25.0~\\pm ~0.5~\\,\\textrm{MeV} $$  <math> <mrow> <msub> <mi>\u0393</mi> <mrow> <mi>\u03c8</mi> <mo>(</mo> <mn>3770</mn> <mo>)</mo> </mrow> </msub> <mspace width=\"3.33333pt\"></mspace> <mo>=</mo> <mspace width=\"3.33333pt\"></mspace> <mn>25.0</mn> <mspace width=\"3.33333pt\"></mspace> <mo>\u00b1</mo> <mspace width=\"3.33333pt\"></mspace> <mn>0.5</mn> <mspace width=\"3.33333pt\"></mspace> <mspace width=\"0.166667em\"></mspace> <mtext>MeV</mtext> </mrow> </math>  . Moreover, we find the decay to  $$D^+D^-$$  <math> <mrow> <msup> <mi>D</mi> <mo>+</mo> </msup> <msup> <mi>D</mi> <mo>-</mo> </msup> </mrow> </math>   and  $$D^0\\bar{D}^0$$  <math> <mrow> <msup> <mi>D</mi> <mn>0</mn> </msup> <msup> <mrow> <mover> <mrow> <mi>D</mi> </mrow> <mrow> <mo>\u00af</mo> </mrow> </mover> </mrow> <mn>0</mn> </msup> </mrow> </math>   to be consistent with isospin symmetry and derive an upper bound on the branching ratio  $${\\mathcal {B}}(\\psi (3770) \\rightarrow \\text {non-}D\\bar{D}) &lt; 6\\%$$  <math> <mrow> <mi>B</mi> <mo>(</mo> <mi>\u03c8</mi> <mo>(</mo> <mn>3770</mn> <mo>)</mo> <mo>\u2192</mo> <mtext>non-</mtext> <mi>D</mi> <mover> <mrow> <mi>D</mi> </mrow> <mrow> <mo>\u00af</mo> </mrow> </mover> <mo>)</mo> <mo>&lt;</mo> <mn>6</mn> <mo>%</mo> </mrow> </math>   at  $$90\\%$$  <math> <mrow> <mn>90</mn> <mo>%</mo> </mrow> </math>   probability."
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Published on:
09 May 2024
Publisher:
Springer
Published in:
European Physical Journal C , Volume 84 (2024)
Issue 5
Pages 1-12
DOI:
https://doi.org/10.1140/epjc/s10052-024-12785-8
arXiv:
2312.00619
Copyrights:
The Author(s)
Licence:
CC-BY-4.0

Fulltext files: