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)

The roles of the $ \Delta (1232) $ , $ {N}^{*}(1520) $ , and $ {N}^{*}(1650) $ resonances in the $ \gamma p\to{\pi }^{0}{\pi }^{0}p $ reaction near threshold is investigated within an effective Lagrangian approach. The differential cross sections of the $ \gamma p\to{\pi }^{0}{\pi }^{0}p $ reaction was calculated including contributions from the $ \Delta (1232) $ , $ {N}^{*}(1520) $ , and $ {N}^{*}(1650) $ intermediate states decaying into $ \pi^0 p $ via the $\textit{s}$-channel nucleon pole and $\textit{t}$-channel $\textit{ρ}$ exchange. Current experimental measurements were well reproduced. The production of $ \Delta(1232) $ was mainly from the mechanism of the $\textit{s}$-channel nucleon pole, while the $ {N}^{*}(1520) $ and $ {N}^{*}(1650) $ were produced from the mechanism of the $\textit{t}$-channel $\textit{ρ}$ exchange. More experimental data on the $ \gamma p \to \pi^0 \pi^0 p $ reaction could be used to explore the properties of the low-lying excited baryon state.

Meng-Yuan Dai

Si-Wei Liu

Cheng Chen

De-Min Li

En Wang

Ju-Jun Xie

Roles of ${\boldsymbol\Delta(\bf 1232)}$ , ${\boldsymbol N^*(\bf 1520)}$ , and ${\boldsymbol N^*(\bf 1650)}$ resonances in ${\boldsymbol\gamma \boldsymbol p\to \boldsymbol\pi^{\bf 0} \boldsymbol\pi^{\bf 0}\boldsymbol p}$ reaction within an effective Lagrangian approach * Supported by the National Key R&D Program of China (2023YFA1606703, 2024YFE0105200), the Natural Science Foundation of Henan Province, China (232300421140, 222300420554), and the National Natural Science Foundation of China (12435007, 12361141819, 12475086, 12192263)

We report on the first measurement of the elemental fragmentation cross sections (EFCSs) of <math><mmultiscripts><mrow><mi>Si</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>29</mn><mo>−</mo><mn>33</mn></mrow></mmultiscripts></math> on a carbon target at ∼230 MeV/nucleon. The experimental data covering charge changes of ΔZ = 1-4 are reproduced well by the isospin-dependent quantum molecular dynamics (IQMD) coupled with the evaporation GEMINI (IQMD+GEMINI) model. We further explore the mechanisms underlying the single-proton removal reaction in this model framework. We conclude that the cross sections from direct proton knockout exhibit an overall weak dependence on the mass number of Si projectiles. The proton evaporation induced after the projectile excitation significantly affects the cross sections for neutron-deficient Si isotopes, while neutron evaporation plays a crucial role in the reactions of neutron-rich Si isotopes. It is presented that the relative magnitude of one-proton and one-neutron separation energies is an essential factor that influences evaporation processes. Therefore, proton evaporation should be incorporated into the reaction model in addition to the direct proton knockout in analyses of Gade-Tostevin systematic for single-proton removal reactions.

Guang-Shuai Li

Bao-Hua Sun

Jun Su

Japan

Isao Tanihata

Satoru Terashima

Germany

Jian-Wei Zhao

Er-Xi Xiao

Ji-Chao Zhang

Liu-Chun He

Ge Guo

Wei-Ping Lin

Wen-Jian Lin

Chuan-Ye Liu

Chen-Gui Lu

Bo Mei

Dan-Yang Pang

Ye-Lei Sun

Zhi-Yu Sun

Meng Wang

Feng Wang

Jing Wang

Shi-Tao Wang

Xiu-Lin Wei

Xiao-Dong Xu

Jun-Yao Xu

Li-Hua Zhu

Yong Zheng

Mei-Xue Zhang

Xue-Heng Zhang

Single-proton removal reaction in the IQMD+GEMINI model benchmarked by elemental fragmentation cross sections of Si on carbon at ∼230 MeV/nucleon

Motivated by the recent experimental measurements, we have investigated the Cabibbo-favored process <math><msubsup><mi>Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo>→</mo><mi>p</mi><msup><mover><mi>K</mi><mo>¯</mo></mover><mn>0</mn></msup><mi>η</mi></math>, where the <math><mi>N</mi><mo>(</mo><mn>1535</mn><mo>)</mo></math> resonance is dynamically generated from the <math><mi>S</mi></math>-wave pseudoscalar meson-octet baryon interactions within the chiral unitary approach. The contributions from the intermediate <math><mi>N</mi><mo>(</mo><mn>1650</mn><mo>)</mo></math> and the predicted low-lying baryon <math><msup><mi>Σ</mi><mo>*</mo></msup><mo>(</mo><mn>1</mn><mo>/</mo><msup><mn>2</mn><mo>−</mo></msup><mo>)</mo></math> are also considered. In addition, a Breit-Wigner amplitude for the <math><mi>N</mi><mo>(</mo><mn>1535</mn><mo>)</mo></math> resonance is checked. By comparing with the measured <math><mi>η</mi><mi>p</mi></math>, <math><msup><mover><mi>K</mi><mo>¯</mo></mover><mn>0</mn></msup><mi>η</mi></math>, and <math><mi>p</mi><msup><mover><mi>K</mi><mo>¯</mo></mover><mn>0</mn></msup></math> invariant mass squared distributions, our results support the interpretation of <math><mi>N</mi><mo>(</mo><mn>1535</mn><mo>)</mo></math> as a dynamically generated state. Furthermore, we demonstrate that, with the contribution from <math><msup><mi>Σ</mi><mo>*</mo></msup><mo>(</mo><mn>1</mn><mo>/</mo><msup><mn>2</mn><mo>−</mo></msup><mo>)</mo></math> taken into account, the calculated invariant mass distributions agree with the Belle measurements. Future precise measurements of the <math><msubsup><mi>Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo>→</mo><mi>p</mi><msup><mover><mi>K</mi><mo>¯</mo></mover><mn>0</mn></msup><mi>η</mi></math> process can further elucidate the existence of the low-lying baryon <math><msup><mi>Σ</mi><mo>*</mo></msup><mo>(</mo><mn>1</mn><mo>/</mo><msup><mn>2</mn><mo>−</mo></msup><mo>)</mo></math>.

Ying Li

Li-Sheng Geng

Theoretical study of <math><mi>N</mi><mo>(</mo><mn>1535</mn><mo>)</mo></math> and <math><msup><mi>Σ</mi><mo>*</mo></msup><mo>(</mo><mn>1</mn><mo>/</mo><msup><mn>2</mn><mo>−</mo></msup><mo>)</mo></math> in the Cabibbo-favored process <math><msubsup><mi>Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo>→</mo><mi>p</mi><msup><mover><mi>K</mi><mo>¯</mo></mover><mn>0</mn></msup><mi>η</mi></math>

The spin-orbit splitting between neutron 1p orbitals at $^{33}$Si has been deduced using the single-neutron-adding (d,p) reaction in inverse kinematics with a beam of $^{32}$Si, a long-lived radioisotope. Reaction products were analyzed by the newly implemented SOLARIS spectrometer at the reaccelerated-beam facility at the National Superconducting Cyclotron Laboratory. The measurements show reasonable agreement with shell-model calculations that incorporate modern cross-shell interactions, but they contradict the prediction of proton density depletion based on relativistic mean-field theory. The evolution of the neutron 1p-shell orbitals is systematically studied using the present and existing data in the isotonic chains of <math><mi>N</mi><mo>=</mo><mn>17</mn></math>, 19, and 21. In each case, a smooth decrease in the separation of the <math><mn>1</mn><msub><mrow><mi>p</mi></mrow><mrow><mn>3</mn><mo>/</mo><mn>2</mn></mrow></msub></math>-<math><mn>1</mn><msub><mrow><mi>p</mi></mrow><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub></math> orbitals is seen as the respective p-orbitals approach zero binding, suggesting that the finite nuclear potential strongly influences the evolution of nuclear structure in this region.

United States

J. Chen

B.P. Kay

C.R. Hoffman

T.L. Tang

I.A. Tolstukhin

D. Bazin

R.S. Lubna

Spain

Y. Ayyad

S. Beceiro-Novo

Australia

B.J. Coombes

United Kingdom

CERN

S.J. Freeman

L.P. Gaffney

R. Garg

H. Jayatissa

A.N. Kuchera

P. MacGregor

A.J. Mitchell

W. Mittig

B. Monteagudo

A. Munoz-Ramos

C. Müller-Gatermann

Italy

F. Recchia

N. Rijal

C. Santamaria

M.Z. Serikow

D.K. Sharp

J. Smith

J.K. Stecenko

G.L. Wilson

A.H. Wuosmaa

C.X. Yuan

J.C. Zamora

Y.N. Zhang

Evolution of the nuclear spin-orbit splitting explored via the Si( , ) Si reaction using SOLARIS

We present a theoretical study of the <math><msup><mi>Ξ</mi><mo>*</mo></msup><mo>(</mo><mn>1690</mn><mo>)</mo></math> resonance in the <math><msubsup><mi>Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo>→</mo><mi>Λ</mi><msup><mi>K</mi><mo>+</mo></msup><msup><mover><mi>K</mi><mo>¯</mo></mover><mn>0</mn></msup></math> decay, where the weak-interaction part proceeds through the Cabibbo-favored process <math><mi>c</mi><mo>→</mo><mi>s</mi><mo>+</mo><mi>u</mi><mover><mi>d</mi><mo>¯</mo></mover></math>. Next, the intermediate two mesons and one-baryon state can be constructed with a pair of <math><mi>q</mi><mover><mi>q</mi><mo>¯</mo></mover></math> with the vacuum quantum numbers. Finally, the <math><msup><mi>Ξ</mi><mo>*</mo></msup><mo>(</mo><mn>1690</mn><mo>)</mo></math> is mainly produced from the final-state interactions of <math><mover><mi>K</mi><mo>¯</mo></mover><mi>Λ</mi></math> in coupled channels, and this is shown in the <math><mover><mi>K</mi><mo>¯</mo></mover><mi>Λ</mi></math> invariant mass distribution. The scalar meson <math><msub><mi>a</mi><mn>0</mn></msub><mo>(</mo><mn>980</mn><mo>)</mo></math> and nucleon excited state <math><msup><mi>N</mi><mo>*</mo></msup><mo>(</mo><mn>1535</mn><mo>)</mo></math> are also taken into account in the decaying channels <math><msup><mi>K</mi><mo>+</mo></msup><msup><mover><mi>K</mi><mo>¯</mo></mover><mn>0</mn></msup></math> and <math><msup><mi>K</mi><mo>+</mo></msup><mi>Λ</mi></math>, respectively. Within model parameters, the <math><msup><mi>K</mi><mo>+</mo></msup><msup><mover><mi>K</mi><mo>¯</mo></mover><mn>0</mn></msup></math>, <math><msup><mover><mi>K</mi><mo>¯</mo></mover><mn>0</mn></msup><mi>Λ</mi></math>, and <math><msup><mi>K</mi><mo>+</mo></msup><mi>Λ</mi></math> invariant mass distributions are calculated, and it is found that our theoretical results can well reproduce the experimental measurements, especially for the clear peak around 1690 MeV in the <math><mover><mi>K</mi><mo>¯</mo></mover><mi>Λ</mi></math> spectrum. The proposed weak decay process <math><msubsup><mi>Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo>→</mo><mi>Λ</mi><msup><mi>K</mi><mo>+</mo></msup><msup><mover><mi>K</mi><mo>¯</mo></mover><mn>0</mn></msup></math> and the interaction mechanism can provide valuable information on the nature of the <math><msup><mi>Ξ</mi><mo>*</mo></msup><mo>(</mo><mn>1690</mn><mo>)</mo></math> resonance.

Qing-Hua Shen

Theoretical study on <math><msubsup><mi>Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo>→</mo><mi>Λ</mi><msup><mi>K</mi><mo>+</mo></msup><msup><mover><mi>K</mi><mo>¯</mo></mover><mn>0</mn></msup></math> decay and <math><msup><mi>Ξ</mi><mo>*</mo></msup><mo>(</mo><mn>1690</mn><mo>)</mo></math> resonance

We performed ab initio valence-space in-medium similarity renormalization group calculations based on chiral nucleon-nucleon and three-nucleon interactions to study the neutron-rich nuclei around <math><mi>N</mi><mo>=</mo><mn>28</mn></math>, where the experimental and theoretical evidence point to a rapid transition from spherical to rotational regimes. First, the rotational spectra of $^{40}$Mg, $^{42}$Si, and $^{44}$S are established theoretically, anchored by the calculated E2 transition strength. The results suggest that $^{40}$Mg and $^{42}$Si exhibit large deformations. After that, the erosion of the <math><mi>N</mi><mo>=</mo><mn>28</mn></math> shell closure, especially the evolutions of shape deformation and the emergence of shape coexistence, are discussed in <math><mi>N</mi><mo>=</mo><mn>28</mn></math> even-even isotones ranging from $^{40}$Mg to $^{48}$Ca. Finally, the shell evolution of <math><mi>N</mi><mo>=</mo><mn>28</mn></math> in Mg and Si chains is discussed based on the experimental and predicted excitation energies of low-lying states. The results from our ab initio calculations align well with available experimental data, furnishing essential insights into the structure of neutron-rich nuclei, particularly deformations in the vicinity of $^{40}$Mg and $^{42}$Si.

Q. Yuan

J.G. Li

H.H. Li

Calculations for Well Deformed Nuclei: Mg and Si

Quasi-elastic (QEL) scattering measurements have been performed using a $^{28}$Si projectile off a $^{90}$Zr target at energies around the Coulomb barrier. A Bayesian analysis within the framework of coupled channels (CC) calculations is performed in a large parameter space of quadrupole and hexadecapole deformations (<math><msub><mrow><mi>β</mi></mrow><mrow><mn>2</mn></mrow></msub></math> and <math><msub><mrow><mi>β</mi></mrow><mrow><mn>4</mn></mrow></msub></math>) of $^{28}$Si. Our results unambiguously show that $^{28}$Si is an oblate shaped nucleus with <math><msub><mrow><mi>β</mi></mrow><mrow><mn>2</mn></mrow></msub></math>=-<math><mn>0.38</mn><mo>±</mo><mn>0.01</mn></math> which is in excellent agreement with results from electromagnetic probes. The sign and magnitude of quadrupole deformation along with a precise value of hexadecapole deformation (<math><msub><mrow><mi>β</mi></mrow><mrow><mn>4</mn></mrow></msub></math>=+<math><mn>0.03</mn><mo>±</mo><mn>0.01</mn></math>) of $^{28}$Si have been determined for the first time using QEL scattering. A remarkable agreement is obtained between the experimental and calculated <math><msub><mrow><mi>β</mi></mrow><mrow><mn>4</mn></mrow></msub></math> values of $^{28}$Si based on Skyrme-Hartree-Fock method. The present results demonstrate the strong sensitivity of the quasi-elastic scattering to the sign and magnitude to the ground state deformation parameters, thus affirming its suitability to be used for rare exotic nuclei using low intensity RIBs.

India

Y.K. Gupta

V.B. Katariya

G.K. Prajapati

K. Hagino

D. Patel

V. Ranga

U. Garg

L.S. Danu

A. Pal

B.N. Joshi

S. Dubey

V.V. Desai

S. Panwar

N. Kumar

S. Mukhopadhyay

Pawan Singh

N. Sirswal

R. Sariyal

I. Mazumdar

B.V. John

Precise determination of quadrupole and hexadecapole deformation parameters of the -shell Nucleus, Si

New magic numbers have been discovered in the neutron-rich region of the nuclear chart. However, there has been a lack of research on proton-rich nuclei. $^{22}$O, the mirror nucleus of $^{22}$Si, is a double-magic nucleus bearing a high <math><mi>E</mi><mo>(</mo><msubsup><mrow><mn>2</mn></mrow><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msubsup><mo>)</mo></math>. Whether $^{22}$Si exhibits double-magic characters is an intriguing topic. To investigate this matter, we utilized ab initio valence space in-medium similarity renormalization group for $^{22}$Si/$^{22}$O, and their nearby nuclei. Our ab initio calculations provide good descriptions for the double magicity of $^{22}$O, as well as the shell evolution of <math><mi>N</mi><mo>=</mo><mn>14</mn></math> and <math><mi>Z</mi><mo>=</mo><mn>14</mn></math> through <math><mi>E</mi><mo>(</mo><msubsup><mrow><mn>2</mn></mrow><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msubsup><mo>)</mo></math>. The computed <math><mi>E</mi><mo>(</mo><msubsup><mrow><mn>2</mn></mrow><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msubsup><mo>)</mo></math> indicate that the closure of <math><mi>Z</mi><mo>=</mo><mn>14</mn></math> sub-shell in proton-rich nuclei is weaker than the <math><mi>N</mi><mo>=</mo><mn>14</mn></math> sub-shell closure in their mirror nuclei. Particularly, the calculated <math><mi>E</mi><mo>(</mo><msubsup><mrow><mn>2</mn></mrow><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msubsup><mo>)</mo></math> of $^{22}$Si is 800 keV lower than the one of $^{22}$O. To further explore the magicity of $^{22}$Si, the mirror energy difference (MED) of $^{26}$Si/$^{26}$Mg, $^{24}$Si/$^{24}$Ne, as well as $^{22}$Si/$^{22}$O are calculated. The results demonstrate that the calculated MEDs agree well with available experimental data, and the <math><mi>E</mi><mo>(</mo><msubsup><mrow><mn>2</mn></mrow><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msubsup><mo>)</mo></math> values of $^{22,24,26}$Si are all lower than their respective mirror nuclei due to the Thomas-Ehrman shift with large <math><msub><mrow><mi>s</mi></mrow><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub></math> occupation. Moreover, our calculation provides that the many-body configurations of the low-lying state of $^{22}$Si/$^{22}$O are nearly identical despite the fact that the states bearing large MED. In conclusion, our ab initio results suggest that $^{22}$Si is a double magic nucleus, similar to its mirror nucleus $^{22}$O, albeit with a lower <math><mi>E</mi><mo>(</mo><msubsup><mrow><mn>2</mn></mrow><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msubsup><mo>)</mo></math>.

S. Zhang

Y.M. Xing

W. Zuo

Double-magicity of proton drip-line nucleus Si with Calculation

It is believed that there are more fundamental gauge symmetries beyond those described by the Standard Model of particle physics. The scales of these new gauge symmetries are usually too high to be reachable by particle colliders. Considering that the phase transition (PT) relating to the spontaneous breaking of new gauge symmetries to the electroweak symmetry might be strongly first order, we propose considering the stochastic gravitational waves (GW) arising from this phase transition as an indirect way of detecting these new fundamental gauge symmetries. As an illustration, we explore the possibility of detecting the stochastic GW generated from the PT of 
					 in the space-based interferometer detectors. Our study demonstrates that the GW energy spectrum is reachable by the LISA, Tianqin, Taiji, BBO, and DECIGO experiments only for the case where the spontaneous breaking of 
					 is triggered by at least two electroweak singlet scalars.
				

Wei Chao

Wen-Feng Cui

Huai-Ke Guo

Jing Shu

Gravitational wave imprint of new symmetry breaking JS is Supported by the National Natural Science Foundation of China (11647601, 11690022, 11675243) and also Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB23030100). Wei Chao is Supported by the National Natural Science Foundation of China (11775025)