Neutron-rich nuclei near the <math altimg='si6.svg'><mrow><mi>N</mi><mo linebreak='goodbreak'>=</mo><mn>126</mn></mrow></math> shell closure are vital for <italic>r</italic>-process nucleosynthesis but remain challenging to produce. Multinucleon transfer reactions offer a promising route. We investigate the role of shell effects in such processes by extending the CLIM-H model with a deformation-dependent mass formula and a scaling factor <italic>a</italic> that linearly adjusts the shell-correction strength. Calculations for 136Xe on 208Pb, 204Hg, and 208Hg targets reveal a dual role: shell effects enhance few-nucleon transfers near the entrance channel but strongly suppress fragments requiring the transfer of many nucleons, most severely for the doubly magic 208Pb. This suppression stems from the cumulative transfer probabilities and is aggravated by lower survival after deexcitation. Thus, optimal production of exotic <math altimg='si6.svg'><mrow><mi>N</mi><mo linebreak='goodbreak'>=</mo><mn>126</mn></mrow></math> nuclei requires avoiding strongly shell-closed collision partners at <math altimg='si6.svg'><mrow><mi>N</mi><mo linebreak='goodbreak'>=</mo><mn>126</mn></mrow></math>, as exemplified by doubly magic 208Pb. We propose 238U + 204Hg at <italic>E</italic> <inf>c.m.</inf>&#8239;&#8771;&#8239;1.45 <italic>V<inf>B</inf></italic> as a superior system, predicting significantly enhanced yields.

China

F.C. Dai

P.W. Wen

C.J. Lin

J.J. Liu

X.X. Xu

K.L. Wang

Y.D. Chen

H.L. Yang

Role of shell effects on producing neutron-rich nuclei in the <math altimg='si6.svg'><mrow><mi>N</mi><mo linebreak='goodbreak'>=</mo><mn>126</mn></mrow></math> region via multinucleon transfer reactions

We compute the rate of growth of operator size in matrix models by probing the Lin-Maldacena class of geometries with classical probes. We consider massive point particle probes whose proper momentum equals the size of the gauge invariant operator in the matrix model. We work out the example of the BMN Plane Wave Matrix Model using the electrostatic approach and the method of background fluxes. We also work out complexities in the D2 brane as well as NS5 brane limits of the BMN matrix model along with an example of the irrelevant deformation namely the non-Abelian T-dual of $\textit{AdS}$ × $\textit{S}$ . Finally, we carry out a possible calculation of the Krylov complexity on the matrix model counterpart by using a simple reduction ansatz known as the pulsating fuzzy sphere model. We outline an algorithm to define Krylov basis elements for the matrix model and compute a few Lanczos coefficients. Our analysis reveals that both the Krylov basis states as well as Lanczos coefficients are uniquely fixed in terms of the mass parameter of the matrix model.

India

Dibakar Roychowdhury

Krylov complexity for Lin-Maldacena geometries and their holographic duals

The SU(2)–gauged custodial two-Higgs-doublet model, which shares the same global-symmetry properties with the standard model, is studied non-perturbatively on the lattice. The additional Higgs doublet enlarges the scalar spectrum and opens the possibility for spontaneous breaking of the global symmetry. In this work we start by showing the occurrence of spontaneous breaking of the custodial symmetry in a region of the parameter space of the model. Following this, both the spectrum and the running of the gauge coupling of are examined at weak quartic couplings in the presence of the custodial symmetry. The calculations are performed with energy cutoffs ranging from 300 to 600 GeV on a line of constant standard model physics, obtained by tuning bare couplings to fix the ratio between the masses of the Higgs and the $\textit{W}$ bosons, as well as the value of the renormalized gauge coupling at the scale of the $\textit{W}$ boson mass. The realizable masses for the additional scalar states are explored. For the choice of bare quartic couplings in this work, the estimated lower bound of these masses is found to be well below the $\textit{W}$ boson mass, and independent of the cutoff. We also study the finite temperature electroweak transition along this line of constant standard model physics, revealing properties of a smooth crossover behavior.

Italy

Spain

Guilherme Catumba

Japan

Taiwan

Atsuki Hiraguchi

Wei-Shu Hou

Germany

Karl Jansen

Ying-Jer Kao

Alberto Ramos

Mugdha Sarkar

Lattice investigation of custodial two-Higgs-doublet model at weak quartic couplings

Back-angle quasi-elastic (QE) scattering provides critical barrier information in massive nuclear reactions leading to the synthesis of superheavy nuclei. The shapes and peaks of QE barrier distributions serve as fingerprints of nuclear structures and reaction dynamics. Couplings to collective movements can lead to distinctive peaks in the barrier distributions, but the role of multi-phonon and high-spin states has not been thoroughly investigated. In this work, we extend the high-accuracy R-matrix method and the finite element method to solve coupled-channel equations for massive systems. These two methods are demonstrated to be more stable than the widely used modified Numerov method and allows us to include more vibrational and rotational couplings. Using the reactions <math altimg='si1.svg'><mmultiscripts><mrow><mi mathvariant='normal'>Ti</mi></mrow><mprescripts /><none /><mrow><mn>48</mn></mrow></mmultiscripts></math>+ <math altimg='si2.svg'><mmultiscripts><mrow><mi mathvariant='normal'>Pb</mi></mrow><mprescripts /><none /><mrow><mn>208</mn></mrow></mmultiscripts></math> and <math altimg='si3.svg'><mmultiscripts><mrow><mi mathvariant='normal'>V</mi></mrow><mprescripts /><none /><mrow><mn>51</mn></mrow></mmultiscripts><mo linebreak='goodbreak' linebreakstyle='after'>+</mo><msup><mrow /><mrow><mn>248</mn></mrow></msup><mrow><mi mathvariant='normal'>Cm</mi></mrow></math> as examples, calculations show that multi-phonon and high-spin states significantly smooth the barrier distributions, improving the agreement with experimental data. The comparison between the coupled-channel results and those obtained from the orientation average formula is examined. This work can advance the study of superheavy element synthesis by providing reliable barrier information and capture cross sections based on constraints from QE reactions.

Russia

Mongolia

O. Chuluunbaatar

Belgium

P. Descouvemont

A.A. Gusev

S.I. Vinitsky

Role of multi-phonon and high-spin states on the quasi-elastic barrier distributions of massive systems

The mechanism of reactions with weakly-bound proton-rich nuclei at energies near the Coulomb barrier is a long-standing open question owing to the paucity of experimental data. In this study, a complete kinematics measurement was performed for the proton drip-line nucleus $^{17}$F interacting with $^{58}$Ni at four energies near the Coulomb barrier. Thanks to the powerful performance of the detector array, exhaustive information on the reaction channels, such as the differential cross sections for quasielastic scattering, exclusive and inclusive breakup, as well as for fusion-evaporation protons and alphas, was derived for the first time. The angular distributions of quasielastic scattering and exclusive breakup can be described reasonably well by the continuum-discretized coupled-channels calculations. The inclusive breakup was investigated using the three-body model proposed by Ichimura, Austern, and Vincent, and results indicate the non-elastic breakup is the dominant component. The total fusion cross sections were determined by the fusion-evaporation protons and alphas. Based on the measured exclusive breakup data, the analysis of the classical dynamical simulation code PLATYPUS demonstrates that the incomplete fusion plays a minor role. Moreover, compared with $^{16}$O+$^{58}$Ni, both the reaction and total fusion cross sections of $^{17}$F+$^{58}$Ni exhibit an enhancement in the sub-barrier energy region, which mainly arises from couplings to the continuum states. This work indicates that the information of full reaction channels is crucially important to comprehensively understand the reaction mechanisms of weakly bound nuclear systems.

L. Yang

H. Yamaguchi

United States

Jin Lei

M. Mazzocco

N.R. Ma

L.J. Sun

D.X. Wang

G.X. Zhang

K. Abe

South Korea

S.M. Cha

K.Y. Chae

United Kingdom

A. Diaz-Torres

Brazil

J.L. Ferreira

S. Hayakawa

H.M. Jia

D. Kahl

A. Kim

M.S. Kwag

M. La Commara

R. Navarro Pérez

C. Parascandolo

D. Pierroutsakou

J. Rangel

Y. Sakaguchi

C. Signorini

E. Strano

F. Yang

Y.Y. Yang

G.L. Zhang

F.P. Zhong

J. Lubian

Insight into the reaction dynamics of proton drip-line nuclear system F+ Ni at near-barrier energies

Angular distributions of quasielastic scattering and breakup of the neutron-rich halo nucleus $^{11}$Be on a $^{208}$Pb target at an incident energy of 140 MeV (about 3.5 times the Coulomb barrier) were measured at HIRFL-RIBLL. A strong suppression of the Coulomb nuclear interference peak is observed in the measured quasielastic scattering angular distribution. The result demonstrates for the first time the persistence of the strong breakup coupling effect reported so far for reaction systems involving neutron-halo nuclei at this relatively high incident energy. The measured quasielastic scattering cross sections are satisfactorily reproduced by continuum discretized coupled channel (CDCC) calculations as well as by the XCDCC calculations where the deformation of the $^{10}$Be core is taken into account. The angular and energy distributions of the $^{10}$Be fragments could also be well reproduced considering elastic breakup (CDCC and XCDCC) plus nonelastic breakup contributions, with the latter evaluated with the model by Ichimura, Austern and Vincent [1]. The comparison of the $^{10}$Be energy distributions with simple kinematical estimates evidence the presence of a significant post-acceleration effect which, in the (X)CDCC frameworks, is accounted for by continuum-continuum couplings.

F.F. Duan

K. Wang

A.M. Moro

V. Guimarães

D.Y. Pang

J.S. Wang

Z.Y. Sun

A. Di Pietro

X. Liu

G. Yang

J.B. Ma

P. Ma

S.W. Xu

Z. Bai

X.X. Sun

Q. Hu

J.L. Lou

H.X. Li

S.Y. Jin

H.J. Ong

Q. Liu

J.S. Yao

H.K. Qi

Y.H. Zhang

X.H. Zhou

Z.G. Hu

H.S. Xu

Scattering of the halo nucleus Be from a lead target at 3.5 times the Coulomb barrier energy

Even though the Bayesian method has been proved to be powerful in the field of nuclear physics, it has not yet been implemented to study the properties of the reaction systems with exotic nuclei, for instance, the gross feature of the phenomenological interaction potential. So far, the optical model potential was typically evaluated by the traditional frequentist approach. However, contradictive conclusions were drawn, especially on the near-threshold behavior of the imaginary potential: threshold anomaly and abnormal threshold anomaly were derived for $^{6}$Li+$^{209}$Bi and $^{6}$He+$^{208}$Pb even with the same elastic scattering data. In this study, we first applied the Bayesian framework to analyze the elastic scattering data of $^{6}$Li+$^{209}$Bi. It was found that the results of Bayesian statistics strongly depend on the imposed prior distributions. Therefore, the Bayesian method has to be used with extreme caution, since the improper prior knowledge could lead to completely wrong conclusions. Since the elastic scattering data is not informative enough to constrain the prior and posterior distributions, our analysis further indicates that the results from the non-constraint frequentist approach or the flat prior distribution with a reasonable physical-boundary can be employed as convincing prior knowledge of the Bayesian framework. Based on this result, we further applied the Bayesian approach to the transfer reaction $^{208}$Pb($^{7}$Li,$^{6}$He)$^{209}$Bi, to investigate the optical potentials of the neutron halo system $^{6}$He+$^{209}$Bi in the outgoing channel. With the proper prior distributions, the Bayesian analysis on both the $^{6}$Li+$^{209}$Bi and $^{6}$He+$^{208}$Pb confirm the presence of the abnormal threshold anomaly. Therefore the applicability of the dispersion relation remains in doubt.

Y.X. Zhang

S.H. Zhong

T.P. Luo

Bayesian analysis on interactions of exotic nuclear systems

N.T. Zhang

X.Y. Wang

Romania

D. Tudor

B. Bucher

I. Burducea

H. Chen

Z.J. Chen

D. Chesneanu

A.I. Chilug

L.R. Gasques

D.G. Ghita

C. Gomoiu

K. Hagino

S. Kubono

Y.J. Li

W.P. Lin

R. Margineanu

A. Pantelica

I.C. Stefanescu

M. Straticiuc

X.D. Tang

L. Trache

A.S. Umar

W.Y. Xin

Y. Xu

Corrigendum to “Constraining the C+ C astrophysical S-factors with the C+ C measurements at very low energies” [Phys. Lett. B 801 (2020) 135170]

We review lattice results related to pion, kaon, D-meson, B-meson, and nucleon physics with the aim of making them easily accessible to the nuclear and particle physics communities. More specifically, we report on the determination of the light-quark masses, the form factor $$f_+(0)$$ <math><mrow><msub><mi>f</mi><mo>+</mo></msub><mrow><mo>(</mo><mn>0</mn><mo>)</mo></mrow></mrow></math> arising in the semileptonic $$K \rightarrow \pi $$ <math><mrow><mi>K</mi><mo>→</mo><mi>π</mi></mrow></math> transition at zero momentum transfer, as well as the decay constant ratio $$f_K/f_\pi $$ <math><mrow><msub><mi>f</mi><mi>K</mi></msub><mo>/</mo><msub><mi>f</mi><mi>π</mi></msub></mrow></math> and its consequences for the CKM matrix elements $$V_{us}$$ <math><msub><mi>V</mi><mrow><mi>us</mi></mrow></msub></math> and $$V_{ud}$$ <math><msub><mi>V</mi><mrow><mi>ud</mi></mrow></msub></math> . Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of $$SU(2)_L\times SU(2)_R$$ <math><mrow><mi>S</mi><mi>U</mi><msub><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow><mi>L</mi></msub><mo>×</mo><mi>S</mi><mi>U</mi><msub><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow><mi>R</mi></msub></mrow></math> and $$SU(3)_L\times SU(3)_R$$ <math><mrow><mi>S</mi><mi>U</mi><msub><mrow><mo>(</mo><mn>3</mn><mo>)</mo></mrow><mi>L</mi></msub><mo>×</mo><mi>S</mi><mi>U</mi><msub><mrow><mo>(</mo><mn>3</mn><mo>)</mo></mrow><mi>R</mi></msub></mrow></math> Chiral Perturbation Theory. We review the determination of the $$B_K$$ <math><msub><mi>B</mi><mi>K</mi></msub></math> parameter of neutral kaon mixing as well as the additional four B parameters that arise in theories of physics beyond the Standard Model. For the heavy-quark sector, we provide results for $$m_c$$ <math><msub><mi>m</mi><mi>c</mi></msub></math> and $$m_b$$ <math><msub><mi>m</mi><mi>b</mi></msub></math> as well as those for D- and B-meson decay constants, form factors, and mixing parameters. These are the heavy-quark quantities most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. We review the status of lattice determinations of the strong coupling constant $$\alpha _s$$ <math><msub><mi>α</mi><mi>s</mi></msub></math> . Finally, in this review we have added a new section reviewing results for nucleon matrix elements of the axial, scalar and tensor bilinears, both isovector and flavor diagonal.

S. Aoki

Y. Aoki

France

D. Bečirević

T. Blum

Switzerland

G. Colangelo

S. Collins

Denmark

M. Della Morte

P. Dimopoulos

S. Dürr

H. Fukaya

M. Golterman

Steven Gottlieb

R. Gupta

S. Hashimoto

U. Heller

G. Herdoiza

R. Horsley

A. Jüttner

T. Kaneko

E. Lunghi

R. Mawhinney

A. Nicholson

T. Onogi

C. Pena

A. Portelli

Ireland

A. Ramos

S. Sharpe

J. Simone

S. Simula

R. Sommer

R. Van de Water

A. Vladikas

U. Wenger

H. Wittig

FLAG Review 2019

We use an underground counting lab with an extremely low background to perform an activity measurement for the <math><mmultiscripts><mrow><mtext>C</mtext></mrow><mprescripts></mprescripts><none></none><mrow><mn>12</mn></mrow></mmultiscripts><msup><mrow><mo>+</mo></mrow><mrow><mn>13</mn></mrow></msup><mtext>C</mtext></math> system with energies down to <math><msub><mrow><mi>E</mi></mrow><mrow><mi>c</mi><mo>.</mo><mi>m</mi><mo>.</mo></mrow></msub><mo>=</mo><mn>2.323</mn></math> MeV, at which the $^{12}$C($^{13}$C,p)$^{24}$Na cross section is found to be 0.22(7) nb. The <math><mmultiscripts><mrow><mtext>C</mtext></mrow><mprescripts></mprescripts><none></none><mrow><mn>12</mn></mrow></mmultiscripts><msup><mrow><mo>+</mo></mrow><mrow><mn>13</mn></mrow></msup><mtext>C</mtext></math> fusion cross section is derived with a statistical model calibrated using experimental data. Our new result of the <math><mmultiscripts><mrow><mtext>C</mtext></mrow><mprescripts></mprescripts><none></none><mrow><mn>12</mn></mrow></mmultiscripts><msup><mrow><mo>+</mo></mrow><mrow><mn>13</mn></mrow></msup><mtext>C</mtext></math> fusion cross section is the first decisive evidence in the carbon isotope systems which rules out the existence of the astrophysical S-factor maximum predicted by the phenomenological hindrance model, while confirming the rising trend of the S-factor towards lower energies predicted by other models, such as CC-M3Y+Rep, DC-TDHF, KNS, SPP and ESW. After normalizing the model predictions with our data, a more reliable upper limit is established for the <math><mmultiscripts><mrow><mtext>C</mtext></mrow><mprescripts></mprescripts><none></none><mrow><mn>12</mn></mrow></mmultiscripts><msup><mrow><mo>+</mo></mrow><mrow><mn>12</mn></mrow></msup><mtext>C</mtext></math> fusion cross sections at stellar energies.

Constraining the C+ C astrophysical S-factors with the C+ C measurements at very low energies