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.

China

Qi Lu

Kai-Yuan Zhang

Shi-Sheng Zhang

Triaxial shape of the one-proton emitter Lu

Exploiting an evolution scheme for parton distribution functions (DFs) that is all-orders exact, contemporary lattice-QCD (lQCD) results for low-order Mellin moments of the pion valence quark DF are shown to be mutually consistent. The analysis introduces a means by which key odd moments can be obtained from the even moments in circumstances where only the latter are available. Combining these elements, one arrives at parameter-free lQCD-based predictions for the pointwise behaviour of pion valence, glue, and sea DFs, with sound uncertainty estimates. The behaviour of the pion DFs at large light-front momentum fraction, <math><mi>x</mi><mo>≳</mo><mn>0.85</mn></math>, is found to be consistent with QCD expectations and continuum analyses of pion structure functions, i.e., damping like <math><msup><mrow><mo>(</mo><mn>1</mn><mo>−</mo><mi>x</mi><mo>)</mo></mrow><mrow><msub><mrow><mi>β</mi></mrow><mrow><mi>parton</mi></mrow></msub></mrow></msup></math>, with <math><msub><mrow><mi>β</mi></mrow><mrow><mi>valence</mi></mrow></msub><mo>≈</mo><mn>2.4</mn></math>, <math><msub><mrow><mi>β</mi></mrow><mrow><mi>glue</mi></mrow></msub><mo>≈</mo><mn>3.6</mn></math>, <math><msub><mrow><mi>β</mi></mrow><mrow><mi>sea</mi></mrow></msub><mo>≈</mo><mn>4.6</mn></math>. It may be possible to test these predictions using data from forthcoming experiments.

Ya Lu

Spain

Yin-Zhen Xu

Khépani Raya

Craig D. Roberts

José Rodríguez-Quintero

Pion distribution functions from low-order Mellin moments

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

Working with proton and pion valence distribution functions (DFs) determined consistently at the same, unique hadron scale and exploiting the possibility that there is an effective charge which defines an evolution scheme for DFs that is all-orders exact, we obtain a unified body of predictions for all proton and pion DFs – valence, glue, and four-flavour-separated sea. Whilst the hadron light-front momentum fractions carried by identifiable parton classes are the same for the proton and pion at any scale, the pointwise behaviour of the DFs is strongly hadron-dependent. All calculated distributions comply with quantum chromodynamics constraints on low- and high-x scaling behaviour and, owing to emergent hadron mass, pion DFs are the most dilated. These results aid in elucidating the sources of similarities and differences between proton and pion structure.

Lei Chang

Mexico

Proton and pion distribution functions in counterpoint

A Poincaré-covariant <math><mrow><mi>quark</mi><mo>+</mo><mi>diquark</mi></mrow></math> Faddeev equation is used to develop insights into the structure of the four lightest <math><mo>(</mo><mi>I</mi><mo>,</mo><msup><mi>J</mi><mi>P</mi></msup><mo>=</mo><mfrac><mn>3</mn><mn>2</mn></mfrac><mo>,</mo><msup><mfrac><mn>3</mn><mn>2</mn></mfrac><mo>±</mo></msup><mo>)</mo></math> baryon multiplets. While these systems can contain isovector-axialvector and isovector-vector diquarks, one may neglect the latter and still arrive at a reliable description. The <math><mo>(</mo><mfrac><mn>3</mn><mn>2</mn></mfrac><mo>,</mo><msup><mfrac><mn>3</mn><mn>2</mn></mfrac><mo>+</mo></msup><mo>)</mo></math> states are the simpler systems, with features that bear some resemblance to quark model pictures, e.g., their most prominent rest-frame orbital angular momentum component is <math><mi>S</mi></math>-wave and the <math><mrow><mi>Δ</mi><mo>(</mo><mn>1600</mn><mo>)</mo><msup><mrow><mfrac><mrow><mn>3</mn></mrow><mrow><mn>2</mn></mrow></mfrac></mrow><mrow><mo>+</mo></mrow></msup></mrow></math> may reasonably be viewed as a radial excitation of the <math><mi>Δ</mi><mo>(</mo><mn>1232</mn><mo>)</mo><msup><mfrac><mn>3</mn><mn>2</mn></mfrac><mo>+</mo></msup></math>. The <math><mo>(</mo><mfrac><mn>3</mn><mn>2</mn></mfrac><mo>,</mo><msup><mfrac><mn>3</mn><mn>2</mn></mfrac><mo>−</mo></msup><mo>)</mo></math> states are more complex: the <math><mi>Δ</mi><mo>(</mo><mn>1940</mn><mo>)</mo><msup><mfrac><mn>3</mn><mn>2</mn></mfrac><mo>−</mo></msup></math> expresses little of the character of a radial excitation of the <math><mi>Δ</mi><mo>(</mo><mn>1700</mn><mo>)</mo><msup><mfrac><mn>3</mn><mn>2</mn></mfrac><mo>−</mo></msup></math>; and while the rest-frame wave function of the latter is predominantly <math><mi>P</mi></math>-wave, the leading piece in the <math><mi>Δ</mi><mo>(</mo><mn>1940</mn><mo>)</mo><msup><mfrac><mn>3</mn><mn>2</mn></mfrac><mo>−</mo></msup></math> wave function is <math><mi>S</mi></math>-wave, in conflict with quark model expectations. Experiments that can test these predictions, such as large momentum transfer resonance electroexcitation, may shed light on the nature of emergent hadron mass.

Langtian Liu

Chen Chen

Jorge Segovia

Composition of low-lying <math><mrow><mi>J</mi><mo>=</mo><msup><mrow><mfrac><mrow><mn>3</mn></mrow><mrow><mn>2</mn></mrow></mfrac></mrow><mrow><mo>±</mo></mrow></msup></mrow></math> <math><mrow><mi>Δ</mi></mrow></math>-baryons

We study the quasi-two-body decays 
					 by employing the perturbative QCD (PQCD) factorization approach, where the charmonia 
					 represents 
					 and 
					. The corresponding decay channels are studied by constructing the kaon-pion distribution amplitude (DA) 
					, which comprises important final state interactions between the kaon and pion in the resonant region. Relativistic Breit-Wigner formulas are adopted to parameterize the time-like form factor 
					 appearing in the kaon-pion DAs. The SU(3) flavor symmetry breaking effect resulting from the mass difference between the kaon and pion is taken into account, which makes significant contributions to the longitudinal polarizations. The observed branching ratios and the polarization fractions of 
					 are accommodated by tuning hadronic parameters for the kaon-pion DAs. The PQCD predictions for 
					 modes from the same set of parameters can be tested by precise data obtained in the future from LHCb and Belle II experiments.
				

Ya Li

Zhou Rui

Zhen-Jun Xiao

P-wave contributions to B(s)→ψKπ decays in perturbative QCD approach Supported by the National Natural Science Foundation of China (11947013, 11605060, 11775117, 11547020); Ya Li is also Supported by the Natural Science Foundation of Jiangsu Province (BK20190508) and the Research Start-up Funding of Nanjing Agricultural University; Zhou Rui is Supported in part by the Natural Science Foundation of Hebei Province (A2019209449)

The quenching of the experimental spectroscopic factor for proton emission from the short-lived d3/2 isomeric state in 151 m Lu was a long-standing problem. In the present work, proton emission from this isomer has been reinvestigated in an experiment at the Accelerator Laboratory of the University of Jyväskylä. The proton-decay energy and half-life of this isomer were measured to be 1295(5) keV and 15.4(8) μs, respectively, in agreement with another recent study. These new experimental data can resolve the discrepancy in the spectroscopic factor calculated using the spherical WKB approximation. Using the R-matrix approach it is found that the proton formation probability indicates no significant hindrance for the proton decay of 151 m Lu.

F. Wang

B.H. Sun

United Kingdom

Z. Liu

R.D. Page

Sweden

C. Qi

Finland

C. Scholey

S.F. Ashley

L. Bianco

I.J. Cullen

Austria

I.G. Darby

S. Eeckhaudt

Canada

A.B. Garnsworthy

W. Gelletly

M.B. Gomez-Hornillos

T. Grahn

P.T. Greenlees

D.G. Jenkins

G.A. Jones

South Africa

P. Jones

D.T. Joss

R. Julin

S. Juutinen

S. Ketelhut

S. Khan

A. Kishada

M. Leino

Japan

M. Niikura

Belgium

M. Nyman

J. Pakarinen

S. Pietri

Z. Podolyak

P. Rahkila

S. Rigby

J. Saren

T. Shizuma

J. Sorri

S. Steer

J. Thomson

N.J. Thompson

J. Uusitalo

P.M. Walker

Netherlands

S. Williams

H.F. Zhang

W.Q. Zhang

L.H. Zhu

Spectroscopic factor and proton formation probability for the d 3/2 proton emitter 151 m Lu

We investigate the dynamical chiral symmetry breaking and its restoration at finite density and temperature within the two-flavor Nambu–Jona–Lasinio model, and mainly focus on the critical behaviors near the critical end point (CEP) and tricritical point (TCP) of quantum chromodynamics. The multi-solution region of the Nambu and Wigner ones is determined in the phase diagram for the massive and massless current quark, respectively. We use the various susceptibilities to locate the CEP/TCP and then extract the critical exponents near them. Our calculations reveal that the various susceptibilities share the same critical behaviors for the physical current quark mass, while they show different features in the chiral limit.

Yi-Lun Du

Zhu-Fang Cui

Hong-Shi Zong

Critical behaviors near the (tri-)critical end point of QCD within the NJL model