Nuclear Theory·nucl-th

Thursday·July 13, 2017

9 papers—4 primary·5 cross-listed

01
Strongly screening electron capture rates of chromium isotopes in presupernova
Jing-Jing Liu · Qiu-He Peng · Liang-Huan Hao · Xiao-Ping Kang · Dong-Mei Liu
Taking into account the effect of electron screening on the electron energy and electron capture threshold energy, by using the method of Shell-Model Monte Carlo and Random Phase Approximation theory, we investigate the strong electron screening capture rates of chromium isotopes according to the linear response theory screening model. The strong screening rates can decrease by about 40.43\% (e.g., for $^{60}$ Cr at $T_{9} = 3.44, Y_{e} = 0.43$ ). Our conclusions may be helpful to the researches of supernova explosion and numerical simulation.
nucl-thRes.Astron.Astrophys.(2017)·19 citations
02
Multiple multi-orbit pairing algebras in shell model and interacting boson models
V.K.B. Kota
In nuclei with valence nucleons are say identical nucleons and say these nucleons occupy several- $j$ orbits, then it is possible to consider pair creation operator $S_{+}$ to be a sum of the single- $j$ shell pair creation operators $S_{+} (j)$ with arbitrary phases, $S_{+} = \sum_{j} α_{j} S_{+} (j); α_{j} = \pm 1$ . In this situation, it is possible to define multi-orbit or generalized seniority that corresponds to the quasi-spin $S U (2)$ algebra generated by $S_{+}$ , $S_{-} = (S_{+})^{†}$ and $S_{0} = (n^- Ω) /2$ operators; $n^$ is number operator and $Ω = [\sum_{j} (2 j + 1)] /2$ . There are now multiple pairing quasi-spin $S U (2)$ algebras. Also, the $α_{j}$ 's and the generators of the corresponding generalized seniority generating sympletic algebras $S p (2Ω)$ in $U (2Ω) \supset S p (2Ω)$ have one-to-one correspondence. Using these, derived are the special seniority selection rules for electromagnetic transitions. A particular choice for $α_{j}$ 's as advocated by Arvieu and Moszkowski (AM) in the past gives pairing Hamiltonians having maximum correlation with well known effective interactions. The various results derived for identical fermion systems are shown to extend to identical boson systems with the bosons occupying several- $ℓ$ orbits as for example in $s d$ , $s p$ , $s d g$ and $s d p f$ IBM's. The quasi-spin algebra here is $S U (1, 1)$ and the generalized seniority quantum number is generated by $S O (2Ω)$ in $U (2Ω) \supset S O (2Ω)$ . The different $S O (2Ω)$ algebras here will be important in the study of quantum phase transitions and order-chaos transitions in nuclei.
nucl-thmath-phmath.MPBulg.J.Phys.(2017)·4 citations
03
Prolate over oblate dominance in deformed nuclei as a consequence of the SU(3) symmetry and the Pauli principle
Dennis Bonatsos
We show that the dominance of prolate over oblate shapes in even-even deformed nuclei can be derived from the SU(3) symmetry and the Pauli principle.
nucl-thEPJA(2017)·41 citations
04
TMDs of Spin-one Targets: Formalism and Covariant Calculations
Yu Ninomiya🇯🇵 · Wolfgang Bentz🇯🇵 · Ian C. Cloët🇺🇸
We present a covariant formulation and model calculations of transverse momentum-dependent quark distribution functions (TMDs) for spin-one hadrons. Emphasis is placed on a description of these 3-dimensional distribution functions which is independent of any constraints on the spin quantization axis. We apply our covariant spin description to all nine leading-twist time-reversal even $ρ$ meson TMDs in the framework provided by the Nambu--Jona-Lasinio model, incorporating important aspects of quark confinement via the infrared cut-off in the proper-time regularization scheme. In particular, the behavior of the 3-dimensional TMDs in a tensor polarized spin-one hadron are illustrated. Sum rules and positivity constraints are discussed in detail. Results of particular interest include the finding that the tensor polarized TMDs -- associated with spin-one hadrons -- are very sensitive to quark orbital angular momentum, and that the TMDs associated with the quark operator $γ^{+} γ_{T} γ_{5}$ would vanish were it not for dynamical chiral symmetry breaking. In addition, we find that 44% of the $ρ$ meson's spin is carried by the orbital angular momentum of the quarks, and that the magnitude of the tensor polarized quark distribution function is about 30% of the unpolarized quark distribution. A qualitative comparison between our results for the tensor structure of a quark-antiquark bound state is made to previous experimental and theoretical results for the two-nucleon (deuteron) bound state.
nucl-thhep-phPRC(2017)·50 citations
05
Anthropics of Aluminum-26 Decay and Biological Homochirality
McCullen Sandora🇺🇸
Results of recent experiment reinstate feasibility to the hypothesis that biomolecular homochirality originates from beta decay. Coupled with hints that this process occurred extraterrestrially suggests aluminum-26 as the most likely source. If true, then its appropriateness is highly dependent on the half-life and energy of this decay. Demanding that this mechanism hold places new constraints on the anthropically allowed range for multiple parameters, including the electron mass, difference between up and down quark masses, the fine structure constant, and the electroweak scale. These new constraints on particle masses are tighter than those previously found. However, one edge of the allowed region is nearly degenerate with an existing bound, which, using what is termed here as `the principle of noncoincident peril', is argued to be a strong indicator that the fine structure constant must be an environmental parameter in the multiverse.
↳ astro-ph.COhep-thnucl-thJCAP(2017)·3 citations
06
Generalized Ensemble Theory with Non-extensive Statistics
Ke-Ming Shen🇨🇳 · Ben-Wei Zhang🇨🇳 · En-Ke Wang🇨🇳
The non-extensive canonical ensemble theory is reconsidered with the method of Lagrange multipliers by maximizing Tsallis entropy, with the constraint that the normalized term of Tsallis' $q -$ average of physical quantities, the sum $\sum p_{j}^{q}$ , is independent of the probability $p_{i}$ for Tsallis parameter $q$ . The self-referential problem in the deduced probability and thermal quantities in non-extensive statistics is thus avoided, and thermodynamical relationships are obtained in a consistent and natural way. We also extend the study to the non-extensive grand canonical ensemble theory and obtain the $q$ -deformed Bose-Einstein distribution as well as the $q$ -deformed Fermi-Dirac distribution. The theory is further applied to the generalized Planck law to demonstrate the distinct behaviors of the various generalized $q$ -distribution functions discussed in literature.
↳ cond-mat.stat-mechmath-phmath.MPnucl-thPhysica A(2017)·8 citations
07
Possible hadronic molecules composed of the doubly charmed baryon and nucleon
Lu Meng🇨🇳 · Ning Li🇩🇪 · Shi-lin Zhu🇨🇳
We perform a systematical investigation of the possible deuteron-like bound states with configuration $Ξ_{cc} N (N ˉ)$ , where $N (N ˉ)$ denotes the nucleon (anti-nucleon), in the framework of the one-boson-exchange-potential model. In the spin-triplet sector we take into account both the $^{3} S_{1}$ and $^{3} D_{1}$ channels due to non-vanishing tensor force. There exist several candidates of the loosely bound molecular states for the $Ξ_{cc} N$ and $Ξ_{cc} N ˉ$ systems, which lie below the threshold of $Λ_{c} Λ_{c}$ or $Λ_{c} Λ ˉ_{c}$ . We also investigate the possible loosely bound states with configurations $Λ_{c} N (N ˉ)$ and $Σ_{c} N (N ˉ)$ . These molecular candidates may be searched for at Belle II and LHC in the near future.
↳ hep-phhep-exnucl-thEPJA(2018)·40 citations
08
Probing medium-induced jet splitting and energy loss in heavy-ion collisions
Ning-Bo Chang🇨🇳 · Shanshan Cao🇺🇸 · Guang-You Qin🇨🇳
The nuclear modification of jet splitting in relativistic heavy-ion collisions at RHIC and the LHC energies is studied based on the higher twist formalism. Assuming coherent energy loss for the two splitted subjets, a non-monotonic jet energy dependence is found for the nuclear modification of jet splitting function: strongest modification at intermediate jet energies whereas weaker modification for larger or smaller jet energies. Combined with the smaller size and lower density of the QGP medium at RHIC than at the LHC, this explains the CMS-STAR groomed jet puzzle -- strong nuclear modification of the momentum sharing $z_{g}$ distribution at the LHC whereas no obvious modification of the $z_{g}$ distribution at RHIC. In contrast, the observed nuclear modification pattern of the groomed jet $z_{g}$ distribution cannot be explained solely by independent energy loss of the two subjets. Our result may be tested in future measurements of groomed jets with lower jet energies at the LHC and larger jet energies at RHIC, for different angular separations between the two subjets.
↳ hep-phnucl-thPLB(2018)·73 citations
09
Exotic Doubly Charmed Ds0*(2317)D and Ds1*(2460)D* Molecules
Mario Sanchez Sanchez🇫🇷 · Li-Sheng Geng🇨🇳 · Jun-Xu Lu🇨🇳 · Tetsuo Hyodo🇯🇵 · Manuel Pavon Valderrama🇨🇳
The $D_{s 0}^{*} (2317) D$ and $D_{s 1}^{*} (2460) D^{*}$ heavy meson systems can exchange a kaon that is emitted in S-wave owing to the opposite intrinsic parity of the $D_{s 0}^{*}$ ( $D_{s 1}^{*}$ ) and $D$ ( $D^{*}$ ) mesons. As a consequence of the mass difference of the $D_{s 0}^{*}$ ( $D_{s 1}^{*}$ ) and $D$ ( $D^{*}$ ) mesons, the range of the kaon exchange potential will be significantly longer than expected, corresponding to an effective mass of about $200 MeV$ . The potential will be very strong: the strength of the interaction is proportional to $(m_{D_{s 0}} - m_{D})^{2} / f_{π}^{2}$ and $(m_{D_{s 1}} - m_{D^{*}})^{2} / f_{π}^{2}$ . This combination of range and strength almost guarantees the existence of $D_{s 0}^{*} (2317) D$ and $D_{s 1}^{*} (2460) D^{*}$ bound states with $J^{P} = 0^{-}$ and $J^{P} = 0^{-}, 2^{-}$ respectively. Concrete calculations indicate a binding energy of $5 - 15 MeV$ independently of $J^{P}$ . The $D_{s 0}^{*} (2317) D$ and $D_{s 1}^{*} (2460) D^{*}$ molecules have manifestly exotic flavour quantum numbers: $C = 2$ , $S = 1$ and $I = 1/2$ . We expect the existence of bottom counterparts composed of the $B B_{s 0}$ and $B^{*} B_{s 1}^{*}$ mesons, which will be more bound and have a richer spectrum that might include a shallow P-wave state and an excited S-wave state.
↳ hep-phhep-exhep-latnucl-thPRD(2018)·40 citations

Affiliations

first authorsco-authorsvia INSPIRE