We perform a study of the  $$D_s^+ \rightarrow a_0(980)(f_0(980)) e^+ \nu _e$$  <math> <mrow> <msubsup> <mi>D</mi> <mi>s</mi> <mo>+</mo> </msubsup> <mo>→</mo> <msub> <mi>a</mi> <mn>0</mn> </msub> <mrow> <mo>(</mo> <mn>980</mn> <mo>)</mo> </mrow> <mrow> <mo>(</mo> <msub> <mi>f</mi> <mn>0</mn> </msub> <mrow> <mo>(</mo> <mn>980</mn> <mo>)</mo> </mrow> <mo>)</mo> </mrow> <msup> <mi>e</mi> <mo>+</mo> </msup> <msub> <mi>ν</mi> <mi>e</mi> </msub> </mrow> </math>   reactions investigating the different sources of isospin violation which make the production of the  $$a_0(980)$$  <math> <mrow> <msub> <mi>a</mi> <mn>0</mn> </msub> <mrow> <mo>(</mo> <mn>980</mn> <mo>)</mo> </mrow> </mrow> </math>   possible. We find that loops involving kaons in the production mechanism provide a source of isospin violation since they do not cancel due to the different mass of charged and neutral kaons, but we also find that the main source comes from the breaking of isospin in the meson-meson transition T matrices, which contain information on the nature of the low lying scalar mesons. The reaction is thus very sensitive to the nature of the  $$a_0(980)$$  <math> <mrow> <msub> <mi>a</mi> <mn>0</mn> </msub> <mrow> <mo>(</mo> <mn>980</mn> <mo>)</mo> </mrow> </mrow> </math>   and  $$f_0(980)$$  <math> <mrow> <msub> <mi>f</mi> <mn>0</mn> </msub> <mrow> <mo>(</mo> <mn>980</mn> <mo>)</mo> </mrow> </mrow> </math>   resonances. Our results are consistent with the present upper bound for  $$a_0(980)$$  <math> <mrow> <msub> <mi>a</mi> <mn>0</mn> </msub> <mrow> <mo>(</mo> <mn>980</mn> <mo>)</mo> </mrow> </mrow> </math>   production and only a factor three smaller, indicating that future runs with more statistics should find actual numbers for this reaction from where we can learn more about the origin of the scalar resonances and their nature.

China

Jia-Xin Lin

Jia-Ting Li

Sheng-Juan Jiang

Wei-Hong Liang

Spain

E. Oset

The  $$D_s^+ \rightarrow a_0(980) e^+ \nu _e$$  <math> <mrow> <msubsup> <mi>D</mi> <mi>s</mi> <mo>+</mo> </msubsup> <mo>→</mo> <msub> <mi>a</mi> <mn>0</mn> </msub> <mrow> <mo>(</mo> <mn>980</mn> <mo>)</mo> </mrow> <msup> <mi>e</mi> <mo>+</mo> </msup> <msub> <mi>ν</mi> <mi>e</mi> </msub> </mrow> </math>   reaction and the  $$a_0(980)-f_0(980)$$  <math> <mrow> <msub> <mi>a</mi> <mn>0</mn> </msub> <mrow> <mo>(</mo> <mn>980</mn> <mo>)</mo> </mrow> <mo>-</mo> <msub> <mi>f</mi> <mn>0</mn> </msub> <mrow> <mo>(</mo> <mn>980</mn> <mo>)</mo> </mrow> </mrow> </math>   mixing

The constituent quark model is used to compute the ground and excited state masses of QQQbaryons containing either c or bquarks. The quark model parameters previously used to describe the properties of charmonium and bottomonium states were used in this analysis. The non-relativistic three-body bound state problem is solved by means of the Gaussian expansion method which provides sufficient accuracy and simplifies the subsequent evaluation of the matrix elements. Several low-lying states with quantum numbers 
					 and 
					 are reported. We compare the results with those obtained by the other theoretical formalisms. There is a general agreement for the mass of the ground state in each sector of triply heavy baryons. However, the situation is more puzzling for the excited states, and appropriate comments about the most relevant features of our comparison are given.
				

Gang Yang

Jialun Ping

Pablo G. Ortega

Jorge Segovia

Triply heavy baryons in the constituent quark model Supported by China Postdoctoral Science Foundation (2019M650617), National Natural Science Foundation of China (11535005, 11775118), and by Spanish Ministerio de Economía, Industria y Competitividad under contractsno. FPA2017-86380-P and FPA2016-77177-C2-2-P. P.G.O. acknowledges the financial support from Spanish MINECO's Juan de la Cierva-Incorporación programme, Grant Agreement No. IJCI-2016-28525.

We perform a theoretical study of the <math><msub><mrow><mi>χ</mi></mrow><mrow><mi>c</mi><mi>J</mi></mrow></msub><mo>→</mo><mi>ϕ</mi><msup><mrow><mi>K</mi></mrow><mrow><mo>⁎</mo></mrow></msup><mover><mrow><mi>K</mi></mrow><mrow><mo>¯</mo></mrow></mover><mo>→</mo><mi>ϕ</mi><mi>K</mi><mi>π</mi><mover><mrow><mi>K</mi></mrow><mrow><mo>¯</mo></mrow></mover></math> reaction taking into account the <math><msup><mrow><mi>K</mi></mrow><mrow><mo>⁎</mo></mrow></msup><mover><mrow><mi>K</mi></mrow><mrow><mo>¯</mo></mrow></mover></math> final state interaction, which in the chiral unitary approach is responsible, together with its coupled channels, for the formation of the low lying axial vector mesons, in this case the <math><msub><mrow><mi>h</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>(</mo><mn>1380</mn><mo>)</mo></math> given the selection of quantum numbers. Based on this picture we can easily explain why in the <math><msub><mrow><mi>χ</mi></mrow><mrow><mi>c</mi><mn>0</mn></mrow></msub></math> decay the <math><msub><mrow><mi>h</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>(</mo><mn>1380</mn><mo>)</mo></math> resonance is not produced, and, in the case of <math><msub><mrow><mi>χ</mi></mrow><mrow><mi>c</mi><mn>1</mn></mrow></msub></math> and <math><msub><mrow><mi>χ</mi></mrow><mrow><mi>c</mi><mn>2</mn></mrow></msub></math> decay, why a dip in the <math><msup><mrow><mi>K</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>K</mi></mrow><mrow><mo>−</mo></mrow></msup></math> mass distribution appears in the 1550-1600 MeV region, that in our picture comes from a destructive interference between the tree level mechanism and the rescattering that generates the <math><msub><mrow><mi>h</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>(</mo><mn>1380</mn><mo>)</mo></math> state. Such a dip is not reproduced in pictures where the nominal <math><msub><mrow><mi>h</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>(</mo><mn>1380</mn><mo>)</mo></math> signal is added incoherently to a background, which provides support to the picture where the resonance appears from rescattering of vector-pseudoscalar components.

S. Sakai

The Decay to Testing the Nature of Axial Vector Meson Resonances

Relativistic millicharged particles (<math><msub><mi>χ</mi><mi>q</mi></msub></math>) have been proposed in various extensions to the standard model of particle physics. We consider the scenarios where they are produced at nuclear reactor core and via interactions of cosmic rays with the Earth’s atmosphere. Millicharged particles could also be candidates for dark matter and become relativistic through acceleration by supernova explosion shock waves. The atomic ionization cross section of <math><msub><mi>χ</mi><mi>q</mi></msub></math> with matter are derived with the equivalent photon approximation. Smoking-gun signatures with significant enhancement in the differential cross section are identified. New limits on the mass and charge of <math><msub><mi>χ</mi><mi>q</mi></msub></math> are derived, using data taken with a point-contact germanium detector with 500 g mass functioning at an energy threshold of 300 eV at the Kuo-Sheng Reactor Neutrino Laboratory.

Taiwan

India

L. Singh

United States

J. W. Chen

H. C. Chi

C.P. Liu

M. K. Pandey

H. T. Wong

C. P. Wu

Türkiye

M. Agartioglu

M. Deniz

H. B. Li

S. T. Lin

V. Sharma

M. K. Singh

V. Singh

Q. Yue

Constraints on millicharged particles with low-threshold germanium detectors at Kuo-Sheng Reactor Neutrino Laboratory