We present the first lattice result of the near threshold $ \Lambda_c\Lambda_c $ scattering with $ I(J^P) = 0(0^+) $ . The calculation is performed on two $ N_f = 2+1 $ Wilson-Clover ensembles with pion mass $ m_\pi \sim 303 $ MeV and lattice spacing $ a = 0.07746 $ fm. Lüscher's finite volume method is utilized to extract the scattering parameters from the finite-volume spectrum. The coupled channel $ \Xi_{cc}N $ is ignored in the scattering analysis based on the observation that the energy levels computed from the $ \Lambda_c\Lambda_c $ and $ \Xi_{cc}N $ operators do not mix. The $ \Sigma_c\Sigma_c $ channel is not included either since the energy range explored in this study is well below its threshold. Our results indicate that the interaction in the $ \Lambda_c\Lambda_c $ single channel is repulsive, and the scattering length is determined to be $ a_0 = -0.21(4)(8) $ fm, where the first error is statistical and the second is systematic.

China

Hanyang Xing

Yiqi Geng

Chuan Liu

Liuming Liu

Peng Sun

Jiajun Wu

Zhicheng Yan

Ruilin Zhu

Lattice QCD study of Λ $\textit{c}$ Λ $\textit{c}$ scattering * Supported by NSFC (12293060, 12293061, 12293063, 12175279, 12435002, 12322503, 12175239). L. Liu also acknowledges the Strategic Priority Research Program of the Chinese Academy of Sciences with (XDB34030301) and Guangdong Major Project of Basic and Applied Basic Research (2020B0301030008). We also acknowledge the Science and Education Integration Young Faculty Project of University of Chinese Academy of Sciences (YSBR-101)

In this work, we calculated the form factors of the weak decay process $$\varLambda _b^0 \rightarrow \varLambda _c(2595)^+$$ , where the final charm baryon represents an excited state with spin-parity $$\frac{1}{2}^-$$ . Utilizing the light-cone QCD sum rules approach, we incorporated the contributions of the lowest two charm baryon states: the ground state $$\varLambda _c$$ with $$J^P=\frac{1}{2}^+$$ and the excited state $$\varLambda _c(2595)^+$$ with $$J^P=\frac{1}{2}^-$$ in the hadronic representation of the $$\varLambda _b \rightarrow \varLambda _c(2595)^+$$ transition correlation function. This approach allows us to extract the form factors of the $$\varLambda _b^0 \rightarrow \varLambda _c(2595)^+$$ from $$\varLambda _b^0 \rightarrow \varLambda _c^+$$ transition. During the light-cone QCD sum rules procedure, we employed the light-cone distribution amplitudes (LCDAs) of the $$\varLambda _b$$ baryon. Furthermore, by combining these form factors with the helicity amplitudes of the bottom baryon transition matrix elements, we calculated the differential decay widths for the processes $$\varLambda _b^0 \rightarrow \varLambda _c(2595)^+\ell ^-\bar{\nu }_\ell $$ and provided the optimal choice of the interpolating current for $$\varLambda _c$$ in this process. Additionally, within the lifetime of $$\varLambda _b^0$$ , we obtained the absolute branching fractions for the semileptonic decays $$\varLambda _b^0 \rightarrow \varLambda _c(2595)^+ \ell ^- \bar{\nu }_\ell $$ . With the branching fractions of $$\varLambda _b^0 \rightarrow \varLambda _c(2595)^+ \ell ^- \bar{\nu }_\ell $$ calculated in this work, we also determined the parameter $$\mathcal {R}(\varLambda _c(2595)^+)$$ which tests the lepton flavor universality. This parameter is defined as the ratio of branching fractions $$\mathcal {B}r(\varLambda _b^0 \rightarrow \varLambda _c(2595)^+\tau ^-\bar{\nu }_\tau )$$ and $$\mathcal {B}r(\varLambda _b^0 \rightarrow \varLambda _c(2595)^+\mu ^-\bar{\nu }_\mu )$$ . Our results provide a valuable theoretical test for these decay channels and offer insights into the LCDAs of bottom baryons, paving the way for further in-depth investigations.

Hui-Hui Duan

Yong-Lu Liu

Qin Chang

Ming-Qiu Huang

Form factors of $$\varLambda _b^0 \rightarrow \varLambda _c(2595)^+$$ within light-cone QCD sum rules

The dineutron as a bound chargeless nucleus of two identical nucleons has been attracting attention for many decades. In addition to the study of the formation of a bound dineutron in the outgoing channel of specific nuclear reactions, cross-section estimates have been gaining interest as research targets. We used a traditional neutron activation technique to irradiate Lu samples followed by measurements of the induced activity with HPGe spectrometer in order to detect gamma-peaks of the 175Lu ( <italic>n</italic>, 2 <italic>n</italic>) 174 gLu reaction product when this reaction channel is not open for incident neutron energies. Based on two measurements of the instrumental gamma-ray spectra of Lu samples we reliably identified the presence of the 174 gLu isotope in the outgoing channel of the 175Lu ( <italic>n</italic>, 2 <italic>n</italic>) 174 gLu nuclear reaction. Also, the cross-section for this nuclear reaction was obtained and to be equal <math altimg='si1.svg'><mrow><mn>33</mn><mo>.</mo><msubsup><mn>5</mn><mrow><mo>&#8722;</mo><mn>6.7</mn></mrow><mrow><mo>+</mo><mn>7.0</mn></mrow></msubsup></mrow></math> mb. For the first time, the dineutron as a nuclearreaction product was indirectly detected via statistically significant observation of the induced activity of 174 gLu with a corresponding cross-section estimate.

Ukraine

Ihor Kadenko

Hungary

Barna Biró

Mihály Braun

András Fenyvesi

Kateryna Okopna

Nadiia Sakhno

Loránd Zakàny

Formation of bound dineutrons in the 175Lu ( <italic>n</italic>, 2 <italic>n</italic>) 174 gLu nuclear reaction and its cross-section

We revisit the proton emitter $^{149}$Lu utilizing the recently developed triaxial relativistic Hartree-Bogoliubov theory in continuum (TRHBc). By incorporating the microscopic nuclear structure properties from the TRHBc theory into the WKB approximation, we successfully reproduce the measured proton-emission half-life of $^{149}$Lu within experimental uncertainties. A triaxial ground state characterized by (<math><mi>β</mi><mo>=</mo><mn>0.17</mn><mo>,</mo><mi>γ</mi><mo>=</mo><msup><mrow><mn>31</mn></mrow><mrow><mo>∘</mo></mrow></msup></math>) has been clarified for $^{149}$Lu. The inclusion of triaxiality significantly changes nuclear density distributions and potentials, which results in enhanced binding of both the nuclear system and the proton-emitting orbital. As a result, a slightly extended half-life for the proton emission of $^{149}$Lu is achieved after considering triaxial deformation degrees of freedom. The examination of the dependence of the decay width on triaxial deformation parameters highlights the significance of microscopic description of nuclear deformation beyond the proton dripline.

Qi Lu

Kai-Yuan Zhang

Shi-Sheng Zhang

Triaxial shape of the one-proton emitter Lu

One-proton radioactivity in $^{149}$Lu, the latest identified proton emitter, is studied in the Wentzel-Kramers-Brillouin (WKB) approach with the proton-nucleus potential extracted from the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) for the first time. The predicted half-life turns out to be consistent with the experimental measurement within uncertainties and (almost) independent of the density functionals in the DRHBc theory. Such a microscopic self-consistent calculation reveals that $^{149}$Lu is oblately deformed with a quadrupole deformation <math><msub><mrow><mi>β</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>≈</mo><mo>−</mo><mn>0.18</mn></math>, and rules out the possibility of a prolate quadrupole deformation suggested in the nonadiabatic quasiparticle model. We also check the validity of this approach in the description of $^{150,151}$Lu and their isomeric states. The deviations of the predicted half-lives from their experimental counterparts are mostly smaller than those of the theoretical studies without considering deformation effects. Furthermore, we predict $^{148}$Lu to be a more oblately deformed proton-emitter with a longer half-life than that of $^{149}$Lu, which can be checked in the future. Our studies show that the DRHBc + WKB approach provides a new alternative method to evaluate the half-lives of well-deformed proton emitters.

Yang Xiao

Si-Zhe Xu

Ru-You Zheng

Germany

Xiang-Xiang Sun

Li-Sheng Geng

One-proton emission from Lu in the DRHBc+WKB approach

Semileptonic decay processes of <math><mrow><msub><mrow><mi>Ξ</mi></mrow><mrow><mi>c</mi></mrow></msub><mo>→</mo><mi>Ξ</mi><mo>ℓ</mo><msub><mrow><mi>ν</mi></mrow><mrow><mo>ℓ</mo></mrow></msub></mrow></math> are studied by light-cone QCD sum rules in this paper. The six form factors of <math><msub><mi>Ξ</mi><mi>c</mi></msub><mo>→</mo><mi>Ξ</mi></math> semileptonic transition matrix elements are calculated by this method with the light-cone distribution amplitudes of <math><mi>Ξ</mi></math> baryon up to twist six. With the six form factors, the absolute branching ratios of <math><mrow><msubsup><mrow><mi>Ξ</mi></mrow><mrow><mi>c</mi></mrow><mrow><mn>0</mn></mrow></msubsup><mo>→</mo><msup><mrow><mi>Ξ</mi></mrow><mrow><mo>−</mo></mrow></msup><msup><mrow><mo>ℓ</mo></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mo>ℓ</mo></mrow></msub></mrow></math> and <math><mrow><msubsup><mrow><mi>Ξ</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo>+</mo></mrow></msubsup><mo>→</mo><msup><mrow><mi>Ξ</mi></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mo>ℓ</mo></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mo>ℓ</mo></mrow></msub></mrow></math> are calculated by the helicity amplitude formalism of semileptonic differential decay widths. The ratios of absolute branching ratios of electron and muon final-state processes give the proof of lepton flavor universality. Our results are in accordance with the recent experimental and theoretical reports.

Semileptonic decay of <math><mrow><msub><mrow><mi>Ξ</mi></mrow><mrow><mi>c</mi></mrow></msub><mo>→</mo><mi>Ξ</mi><msup><mrow><mo>ℓ</mo></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mo>ℓ</mo></mrow></msub></mrow></math> from light-cone QCD sum rules

In this work, we analyze the semileptonic decay processes of $$\varLambda _b \rightarrow \varLambda _c$$ <math> <mrow> <msub> <mi>Λ</mi> <mi>b</mi> </msub> <mo>→</mo> <msub> <mi>Λ</mi> <mi>c</mi> </msub> </mrow> </math> in the light-cone sum rule approach. In order to calculate the form factors of the $$\varLambda _b$$ <math> <msub> <mi>Λ</mi> <mi>b</mi> </msub> </math> baryon transition matrix element, we use the light-cone distribution amplitudes of $$\varLambda _b$$ <math> <msub> <mi>Λ</mi> <mi>b</mi> </msub> </math> obtained from the QCD sum rule in the heavy quark effective field theory framework. With the calculation of the six form factors of the $$\varLambda _b \rightarrow \varLambda _c$$ <math> <mrow> <msub> <mi>Λ</mi> <mi>b</mi> </msub> <mo>→</mo> <msub> <mi>Λ</mi> <mi>c</mi> </msub> </mrow> </math> transition matrix element, the differential decay widths of $$\varLambda _b^0 \rightarrow \varLambda _c^+ \ell ^- {\overline{\nu }}_\ell (\ell = e, ~\mu , ~\tau )$$ <math> <mrow> <msubsup> <mi>Λ</mi> <mi>b</mi> <mn>0</mn> </msubsup> <mo>→</mo> <msubsup> <mi>Λ</mi> <mi>c</mi> <mo>+</mo> </msubsup> <msup> <mi>ℓ</mi> <mo>-</mo> </msup> <msub> <mover> <mi>ν</mi> <mo>¯</mo> </mover> <mi>ℓ</mi> </msub> <mrow> <mo>(</mo> <mi>ℓ</mi> <mo>=</mo> <mi>e</mi> <mo>,</mo> <mspace width="3.33333pt"></mspace> <mi>μ</mi> <mo>,</mo> <mspace width="3.33333pt"></mspace> <mi>τ</mi> <mo>)</mo> </mrow> </mrow> </math> and their absolute branching fractions are obtained. Additionally, the ratio of $$R(\varLambda _c^+) \equiv {\mathcal {B}}r(\varLambda _b^0 \rightarrow \varLambda _c^+ \tau ^- {\overline{\nu }}_\tau )/{\mathcal {B}}r(\varLambda _b^0 \rightarrow \varLambda _c^+ \mu ^- {\overline{\nu }}_\mu )$$ <math> <mrow> <mi>R</mi> <mrow> <mo>(</mo> <msubsup> <mi>Λ</mi> <mi>c</mi> <mo>+</mo> </msubsup> <mo>)</mo> </mrow> <mo>≡</mo> <mi>B</mi> <mi>r</mi> <mrow> <mo>(</mo> <msubsup> <mi>Λ</mi> <mi>b</mi> <mn>0</mn> </msubsup> <mo>→</mo> <msubsup> <mi>Λ</mi> <mi>c</mi> <mo>+</mo> </msubsup> <msup> <mi>τ</mi> <mo>-</mo> </msup> <msub> <mover> <mi>ν</mi> <mo>¯</mo> </mover> <mi>τ</mi> </msub> <mo>)</mo> </mrow> <mo>/</mo> <mi>B</mi> <mi>r</mi> <mrow> <mo>(</mo> <msubsup> <mi>Λ</mi> <mi>b</mi> <mn>0</mn> </msubsup> <mo>→</mo> <msubsup> <mi>Λ</mi> <mi>c</mi> <mo>+</mo> </msubsup> <msup> <mi>μ</mi> <mo>-</mo> </msup> <msub> <mover> <mi>ν</mi> <mo>¯</mo> </mover> <mi>μ</mi> </msub> <mo>)</mo> </mrow> </mrow> </math> is also obtained in this work. Our results are in accord with the newest experimental result and other theoretical calculations and predictions.

Light-cone sum rule analysis of semileptonic decays $$\varLambda _b^0 \rightarrow \varLambda _c^+ \ell ^- {\overline{\nu }}_\ell $$ <math> <mrow> <msubsup> <mi>Λ</mi> <mi>b</mi> <mn>0</mn> </msubsup> <mo>→</mo> <msubsup> <mi>Λ</mi> <mi>c</mi> <mo>+</mo> </msubsup> <msup> <mi>ℓ</mi> <mo>-</mo> </msup> <msub> <mover> <mi>ν</mi> <mo>¯</mo> </mover> <mi>ℓ</mi> </msub> </mrow> </math>

In this study, we consider all P-wave   $\Omega_{b}$   states represented by interpolating currents with a derivative and calculate the corresponding masses and pole residues using the QCD sum rule method. Because of the large uncertainties in our calculation compared with the small difference in the masses of the excited   $\Omega_{b}$   states observed by the LHCb collaboration, it is necessary to study other properties of the P-wave   $\Omega_{b}$   states represented by the interpolating currents investigated in the present work to gain a better understanding of the four excited   $\Omega_{b}$   states observed by the LHCb collaboration.

Yong-Jiang Xu

 -wave ω States: Masses and Pole Residues  

In this paper, we construct <math><msubsup><mover><mi>D</mi><mo>¯</mo></mover><mi>s</mi><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msubsup><msup><mi>D</mi><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msup></math>-molecule-type interpolating currents <math><msub><mi>J</mi><mrow><mo>(</mo><mo>±</mo><mo>)</mo><mi>μ</mi></mrow></msub><mo>(</mo><mi>x</mi><mo>)</mo></math> with <math><msup><mi>J</mi><mi>P</mi></msup><mo>=</mo><msup><mn>1</mn><mo>+</mo></msup></math>, calculate the corresponding mass and magnetic moment using the QCD sum rule method and its extension in the weak electromagnetic field, and study the processes of <math><msub><mi>Z</mi><mrow><mo>(</mo><mo>±</mo><mo>)</mo><mi>c</mi><mi>s</mi></mrow></msub></math> to <math><msub><mi>η</mi><mi>c</mi></msub><msup><mi>K</mi><mo>*</mo></msup></math>, <math><mi>J</mi><mo>/</mo><mi>ψ</mi><mi>K</mi></math>, <math><mover><mi>D</mi><mo>¯</mo></mover><msubsup><mi>D</mi><mi>s</mi><mo>*</mo></msubsup></math>, and <math><msup><mover><mi>D</mi><mo>¯</mo></mover><mo>*</mo></msup><msub><mi>D</mi><mi>s</mi></msub></math> via three-point sum rules. The numerical values are <math><msub><mi>m</mi><msub><mi>Z</mi><mrow><mo>(</mo><mo>±</mo><mo>)</mo><mi>c</mi><mi>s</mi></mrow></msub></msub><mo>=</mo><mn>3.9</mn><msubsup><mn>9</mn><mrow><mo>−</mo><mn>0.14</mn></mrow><mrow><mo>+</mo><mn>0.17</mn></mrow></msubsup><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>, <math><msub><mi>λ</mi><msub><mi>Z</mi><mrow><mo>(</mo><mo>±</mo><mo>)</mo><mi>c</mi><mi>s</mi></mrow></msub></msub><mo>=</mo><mn>2.0</mn><msubsup><mn>7</mn><mrow><mo>−</mo><mn>0.16</mn></mrow><mrow><mo>+</mo><mn>0.28</mn></mrow></msubsup><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>2</mn></mrow></msup><mtext> </mtext><mtext> </mtext><msup><mrow><mi>GeV</mi></mrow><mn>5</mn></msup></math>, and <math><mrow><msub><mrow><mi>μ</mi></mrow><mrow><msub><mrow><mi>Z</mi></mrow><mrow><mo>(</mo><mo>±</mo><mo>)</mo><mi>c</mi><mi>s</mi></mrow></msub></mrow></msub><mo>=</mo><mn>0.1</mn><msubsup><mrow><mn>8</mn></mrow><mrow><mo>−</mo><mn>0.09</mn></mrow><mrow><mo>+</mo><mn>0.16</mn></mrow></msubsup><mtext> </mtext><mtext> </mtext><msub><mrow><mi>μ</mi></mrow><mrow><mi>N</mi></mrow></msub></mrow></math> with <math><msub><mi>μ</mi><mi>N</mi></msub></math> the nucleon magneton, <math><msub><mi>Γ</mi><msub><mi>Z</mi><mrow><mo>(</mo><mo>+</mo><mo>)</mo><mi>c</mi><mi>s</mi></mrow></msub></msub><mo>=</mo><mn>17.4</mn><msubsup><mn>7</mn><mrow><mo>−</mo><mn>8.08</mn></mrow><mrow><mo>+</mo><mn>12.70</mn></mrow></msubsup></math>, and <math><msub><mi>Γ</mi><msub><mi>Z</mi><mrow><mo>(</mo><mo>−</mo><mo>)</mo><mi>c</mi><mi>s</mi></mrow></msub></msub><mo>=</mo><mn>13.8</mn><msubsup><mn>6</mn><mrow><mo>−</mo><mn>6.51</mn></mrow><mrow><mo>+</mo><mn>10.37</mn></mrow></msubsup></math>. The masses are in agreement with the recently measured value of <math><msub><mi>Z</mi><mrow><mi>c</mi><mi>s</mi></mrow></msub><mo>(</mo><mn>3985</mn><mo>)</mo></math> by the BESIII Collaboration, <math><msubsup><mi>m</mi><msub><mi>Z</mi><mrow><mi>c</mi><mi>s</mi></mrow></msub><mrow><mi>exp</mi></mrow></msubsup><mo>=</mo><mo>(</mo><msubsup><mn>3982.5</mn><mrow><mo>−</mo><mn>2.6</mn></mrow><mrow><mo>+</mo><mn>1.8</mn></mrow></msubsup><mo>±</mo><mn>2.1</mn><mo>)</mo><mtext> </mtext><mtext> </mtext><mi>MeV</mi></math>. The widths are compatible with the experimental value <math><msubsup><mi>Γ</mi><msub><mi>Z</mi><mrow><mi>c</mi><mi>s</mi></mrow></msub><mrow><mi>exp</mi></mrow></msubsup><mo>=</mo><mspace></mspace><mo>(</mo><msubsup><mn>12.8</mn><mrow><mo>−</mo><mn>4.4</mn></mrow><mrow><mo>+</mo><mn>5.3</mn></mrow></msubsup><mo>±</mo><mn>3.0</mn><mo>)</mo><mtext> </mtext><mtext> </mtext><mi>MeV</mi></math>. The magnetic moment and the various decay modes can help us to determine the inner structure of <math><msub><mi>Z</mi><mrow><mi>c</mi><mi>s</mi></mrow></msub><mo>(</mo><mn>3985</mn><mo>)</mo></math> when being confronted with experimental data in the future.

Chun-Yu Cui

<math><msubsup><mover><mi>D</mi><mo>¯</mo></mover><mi>s</mi><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msubsup><msup><mi>D</mi><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msup></math> molecular state with <math><msup><mi>J</mi><mi>P</mi></msup><mo>=</mo><msup><mn>1</mn><mo>+</mo></msup></math>

In this paper, we tentatively assign the $$P_{c}(4312)$$ <math> <mrow> <msub> <mi>P</mi> <mi>c</mi> </msub> <mrow> <mo>(</mo> <mn>4312</mn> <mo>)</mo> </mrow> </mrow> </math> to be a $$\bar{D}\Sigma _{c}$$ <math> <mrow> <mover> <mrow> <mi>D</mi> </mrow> <mrow> <mo>¯</mo> </mrow> </mover> <msub> <mi>Σ</mi> <mi>c</mi> </msub> </mrow> </math> molecular state with quantum number $$J^{P}=\frac{1}{2}^{-}$$ <math> <mrow> <msup> <mi>J</mi> <mi>P</mi> </msup> <mo>=</mo> <msup> <mfrac> <mn>1</mn> <mn>2</mn> </mfrac> <mo>-</mo> </msup> </mrow> </math> , and calculate its magnetic moment using the QCD sum rule method in external weak electromagnetic field. Starting with the two-point correlation function in external electromagnetic field and expanding it in power of the electromagnetic interaction Hamiltonian, we extract the magnetic moment from the linear response to the external electromagnetic field. The numerical value of the magnetic moment of $$P_{c}(4312)$$ <math> <mrow> <msub> <mi>P</mi> <mi>c</mi> </msub> <mrow> <mo>(</mo> <mn>4312</mn> <mo>)</mo> </mrow> </mrow> </math> is $$\mu _{P_{c}}=1.75^{+0.15}_{-0.11}$$ <math> <mrow> <msub> <mi>μ</mi> <msub> <mi>P</mi> <mi>c</mi> </msub> </msub> <mo>=</mo> <mn>1</mn> <mo>.</mo> <msubsup> <mn>75</mn> <mrow> <mo>-</mo> <mn>0.11</mn> </mrow> <mrow> <mo>+</mo> <mn>0.15</mn> </mrow> </msubsup> </mrow> </math> .

The magnetic moment of $$P_{c}(4312)$$ <math> <mrow> <msub> <mi>P</mi> <mi>c</mi> </msub> <mrow> <mo>(</mo> <mn>4312</mn> <mo>)</mo> </mrow> </mrow> </math> as a $$\bar{D}\Sigma _{c}$$ <math> <mrow> <mover> <mrow> <mi>D</mi> </mrow> <mrow> <mo>¯</mo> </mrow> </mover> <msub> <mi>Σ</mi> <mi>c</mi> </msub> </mrow> </math> molecular state