Nuclear Theory·nucl-th
9 papers—3 primary·6 cross-listed
Avraham Gal🇮🇱 · Daniel Gazda🇸🇪
Charge symmetry breaking (CSB) is particularly strong in the A=4 mirror hypernuclei H--He. Recent four-body no-core shell model calculations that confront this CSB by introducing - mixing to leading-order chiral effective field theory hyperon-nucleon potentials are reviewed, and a shell-model approach to CSB in p-shell hypernuclei is outlined.
S. Sudár (1) · S. M. Qaim (2) ((1) Institute of Experimental Physics, University of Debrecen, Hungary, (2) Institut für Neurowissenschaften und Medizin, INM-5: Nuklearchemie, Forschungszentrum Jülich GmbH, Germany)
The parameter of the spin distribution of the level density was determined for 61 nuclei covering the mass range of 44 to 200. The experimental isomeric cross-section ratios for 25 isomeric pairs were compared with the model calculation to find the best fit to the experimental data. The model calculations were carried out with the TALYS code using the BSFG model for the level density. The reduced values were calculated to describe the deviation of the experimental data from the model calculation. An was introduced calculating the value from the low energy discrete levels of the nucleus. The values seem to be independent of the mass number, their average value near to one. The values also seem to be independent of the average excitation energy in the continuum, indicating that is independent of the excitation energy. The mass number and (N-Z) dependence of the values were studied. The values for the nuclei with odd mass number show an exponential decrease as a function of A or (N-Z). The values for the odd-odd type of nuclei appear to be constant, near one, up to the mass number 110 or (N-Z) of 13. Above these values, the values show exponential decrease. The values for even-even type nuclei decrease exponentially up to A equal to 142 or (N-Z) equal to 20. The values are lower than those for the nearby odd-odd type nuclei. The values increase for nuclei with A between 142 and 156 and (N-Z) between 20 and 28, and they finally reach the value of odd-odd type systematics.
Tochtli Yépez-Martínez🇦🇷 · Osvaldo Civitarese🇦🇷 · Peter O. Hess🇲🇽
The low-energy sector of the mesonic spectrum exhibits some features which may be understood in terms of the SO(4) symmetry contained in the QCD-Hamiltonian written in the Coulomb Gauge. In our previous work we have shown that this is indeed the case when the Instantaneous Color-Charge Interaction (ICCI) is treated by means of non-perturbative many-body linearization techniques. Continuing along this line of description in this work we calculate the width of meson states belonging to the low portion of the spectrum (E <1 GeV ). In spite of the rather simple structure of the Hamiltonian used to calculate the spectra of pseudoscalar and vector mesons, the results for the width of these states follow the pattern of the data.
In this work we study the possible QCD exotic states in the doubly charmed baryon sector. Within chiral effective theory, it is predicted that several excited baryons result from the -wave scattering of ground-state doubly charmed baryons () and light pseudoscalar mesons (). The excited doubly charmed baryons can be classified by the strangeness () and isospin () quantum numbers. Two of the excited states are clearly exotic, in the sense that they cannot be explained by the conventional baryons with three quarks, since their quantum numbers are and . Similar to the charmed scalar meson in scattering and the hyperon in scattering, one bound state below the threshold is predicted in the channel. In addition, two resonant structures are found in the and coupled-channel scattering with . The corresponding pole positions and coupling strengths of the excited doubly charmed baryons are given. The scattering lengths of the ground-state doubly charmed baryons and light pseudoscalar mesons are also predicted. The current study may provide useful guides for future experimental measurements and lattice simulations.
Zuowei Liu🇨🇳 · Yushan Su🇨🇳 · Yue-Lin Sming Tsai🇨🇳 · Bingrong Yu🇨🇳 · Qiang Yuan🇨🇳
Weakly interacting massive particles are a widely well-probed dark matter candidate by the dark matter direct detection experiments. Theoretically, there are a large number of ultraviolet completed models that consist of a weakly interacting massive particle dark matter. The variety of models makes the comparison with the direct detection data complicated and often non-trivial. To overcome this, in the non-relativistic limit, the effective theory was developed in the literature which works very well to significantly reduce the complexity of dark matter-nucleon interactions and to better study the nuclear response functions. In the effective theory framework for a spin-1/2 dark matter, we combine three independent likelihood functions from the latest PandaX, LUX, and XENON1T data, and give a joint limit on each effective coupling. The astrophysical uncertainties of the dark matter distribution are also included in the likelihood. We further discuss the isospin violating cases of the interactions. Finally, for both dimension-five and dimension-six effective theories above the electroweak scale, we give updated limits of the new physics mass scales.
Xiaohui Liu🇨🇳 · Sven-Olaf Moch🇩🇪 · Felix Ringer🇺🇸
We present the first threshold and jet radius jointly resummed cross section for single-inclusive hadronic jet production. We work at next-to-leading logarithmic accuracy and our framework allows for a systematic extension beyond the currently achieved precision. Longstanding numerical issues are overcome by performing the resummation directly in momentum space within Soft Collinear Effective Theory. We present the first numerical results for the LHC and observe an improved description of the available data. Our results are of immediate relevance for LHC precision phenomenology including the extraction of parton distribution functions and the QCD strong coupling constant.
Yuki Shimizu🇯🇵 · Masayasu Harada🇯🇵
We study hadronic molecular states in a coupled system of in channel, using the complex scaling method combined with the Gaussian expansion method. We construct the potential including one pion exchange and one meson exchange with -wave orbital angular momentum. We find that the both mass and width of the pentaquark can be reproduced within a reasonable parameter region, and that its main decay mode is . We extend our analysis to a coupled system of in channel. We find that there exists a doubly charmed baryon of type as a hadronic molecule, the mass and width of which are quite close to those of .
Yuanbin Wu · Jonas Gunst · Christoph H. Keitel · Adriana Pálffy
The optimal parameters for nuclear excitation by electron capture in plasma environments generated by the interaction of ultra-strong optical lasers with solid matter are investigated theoretically. As a case study we consider a 4.85 keV nuclear transition starting from the long-lived Mo isomer that can lead to the release of the stored 2.4 MeV excitation energy. We find that due to the complex plasma dynamics, the nuclear excitation rate and the actual number of excited nuclei do not reach their maximum at the same laser parameters. The nuclear excitation achievable with a high-power optical laser is up to twelve and up to six orders of magnitude larger than the values predicted for direct resonant and secondary plasma-mediated excitation at the x-ray free electron laser, respectively. Our results show that the experimental observation of the nuclear excitation of Mo and the subsequent release of stored energy should be possible at laser facilities available today.
Eduardo S. Fraga🇧🇷 · Maurício Hippert🇧🇷
Current heavy-ion collision experiments might lead to the discovery of a first-order chiral symmetry breaking phase-transition line, ending in a second-order critical point. Nevertheless, the extraction of information about the equilibrium thermodynamic properties of baryonic matter from the highly dynamic, small, noisy and fluctuating environment formed in such collisions is an extremely challenging task. We address some of the limitations present in the experimental search for the QCD critical point.
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