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Title: Charm-meson triangle singularity in e + e annihilation into D * 0 D ¯ 0 + γ

Abstract

We calculate the cross section for $e^+ e^-$ annihilation into $$D^{*0} \bar D^0 +\gamma$$ at center-of-mass energies near the $$D^{*0} \bar D^{*0}$$ threshold under the assumption that $X(3872)$ is a weakly bound charm meson molecule. The Dalitz plot has a $$\bar D^{*0}$$ resonance band in the squared invariant mass $t$ of $$\bar D^0 \gamma$$. In the limit as the decay width of the $$D^{*0}$$ goes to 0, the Dalitz plot also has a narrow band in the squared invariant mass $u$ of $$D^{*0} \bar D^0$$ from a charm-meson triangle singularity. At the physical value of the $$D^{*0}$$ width, the narrow band reduces to a shoulder. Thus the triangle singularity cannot be observed directly as a peak in a differential cross section as a function of $u$. It may however be observed indirectly as a local minimum in the $t$ distribution for events with $u$ below the triangle singularity. The minimum is produced by the Schmid cancellation between triangle loop diagrams and a tree diagram. The observation of this minimum would support the identification of $X(3872)$ as a weakly bound charm meson molecule.

Authors:
; ; ORCiD logo; ORCiD logo
Publication Date:
Research Org.:
The Ohio State Univ., Columbus, OH (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP); Natural Science Foundation of Shandong Province; Fundamental Research Funds of Shandong University
OSTI Identifier:
1631077
Alternate Identifier(s):
OSTI ID: 1782849
Grant/Contract Number:  
SC0011726; ZR2019QA012
Resource Type:
Published Article
Journal Name:
Physical Review D
Additional Journal Information:
Journal Name: Physical Review D Journal Volume: 101 Journal Issue: 9; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Braaten, Eric, He, Li-Ping, Ingles, Kevin, and Jiang, Jun. Charm-meson triangle singularity in e + e − annihilation into D * 0 D ¯ 0 + γ. United States: N. p., 2020. Web. doi:10.1103/PhysRevD.101.096020.
Braaten, Eric, He, Li-Ping, Ingles, Kevin, & Jiang, Jun. Charm-meson triangle singularity in e + e − annihilation into D * 0 D ¯ 0 + γ. United States. https://doi.org/10.1103/PhysRevD.101.096020
Braaten, Eric, He, Li-Ping, Ingles, Kevin, and Jiang, Jun. Thu . "Charm-meson triangle singularity in e + e − annihilation into D * 0 D ¯ 0 + γ". United States. https://doi.org/10.1103/PhysRevD.101.096020.
@article{osti_1631077,
title = {Charm-meson triangle singularity in e + e − annihilation into D * 0 D ¯ 0 + γ},
author = {Braaten, Eric and He, Li-Ping and Ingles, Kevin and Jiang, Jun},
abstractNote = {We calculate the cross section for $e^+ e^-$ annihilation into $D^{*0} \bar D^0 +\gamma$ at center-of-mass energies near the $D^{*0} \bar D^{*0}$ threshold under the assumption that $X(3872)$ is a weakly bound charm meson molecule. The Dalitz plot has a $\bar D^{*0}$ resonance band in the squared invariant mass $t$ of $\bar D^0 \gamma$. In the limit as the decay width of the $D^{*0}$ goes to 0, the Dalitz plot also has a narrow band in the squared invariant mass $u$ of $D^{*0} \bar D^0$ from a charm-meson triangle singularity. At the physical value of the $D^{*0}$ width, the narrow band reduces to a shoulder. Thus the triangle singularity cannot be observed directly as a peak in a differential cross section as a function of $u$. It may however be observed indirectly as a local minimum in the $t$ distribution for events with $u$ below the triangle singularity. The minimum is produced by the Schmid cancellation between triangle loop diagrams and a tree diagram. The observation of this minimum would support the identification of $X(3872)$ as a weakly bound charm meson molecule.},
doi = {10.1103/PhysRevD.101.096020},
journal = {Physical Review D},
number = 9,
volume = 101,
place = {United States},
year = {2020},
month = {5}
}

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