Nuclear Theory·nucl-th

Monday·July 29, 2019

9 papers—7 primary·2 cross-listed

01
[Submitted on 25 Jul 2019]
A renormalized approach to neutrinoless double-beta decay
V. Cirigliano🇺🇸 · W. Dekens🇺🇸 · J. de Vries🇺🇸 · M. L. Graesser🇺🇸 · E. Mereghetti🇺🇸 · S. Pastore🇺🇸 · M. Piarulli🇺🇸 · U. van Kolck🇫🇷 · R. B. Wiringa🇺🇸
The process at the heart of neutrinoless double-beta decay, $nn \to pp e^{-} e^{-}$ induced by a light Majorana neutrino, is investigated in pionless and chiral effective field theory. We show in various regularization schemes the need to introduce a short-range lepton-number-violating operator at leading order, confirming earlier findings. We demonstrate that such a short-range operator is only needed in spin-singlet $S$ -wave transitions, while leading-order transitions involving higher partial waves depend solely on long-range currents. Calculations are extended to include next-to-leading corrections in perturbation theory, where to this order no additional undetermined parameters appear. We establish a connection based on chiral symmetry between neutrinoless double-beta decay and nuclear charge-independence breaking induced by electromagnetism. Data on the latter confirm the need for a leading-order short-range operator, but do not allow for a full determination of the corresponding lepton-number-violating coupling. Using a crude estimate of this coupling, we perform ab initio calculations of the matrix elements for neutrinoless double-beta decay for $^{6}$ He and $^{12}$ Be. We speculate on the phenomenological impact of the leading short-range operator on the basis of these results.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1907.11254 [pdf]
PRC(2019)·141 citations
02
[Submitted on 25 Jul 2019]
Study of collective anisotropies $v_{2}$ and $v_{3}$ and their fluctuations in $p A$ collisions at LHC within a relativistic transport approach
Yifeng Sun🇮🇹 · Salvatore Plumari🇮🇹 · Vincenzo Greco🇮🇹
We have developed a relativistic transport approach at fixed $η / s (T)$ that incorporates initial space fluctuations generated by wounded quark model to study the hadron observables in 5.02 TeV p+Pb collisions. We find that our approach is able to correctly predict quite well several existing experimental measurements assuming a matter with $η / s = 1/4 π$ , a result similar to previous studies within a viscous hydrodynamics approach. Besides, we further discuss the sensitivity of the results on both $η / s (T)$ and the smearing width. Our transport approach has the possibility to include in initial conditions the power law tail associated to minijet, and this improvement extends the agreement with the experimental data to higher $p_{T}$ ranges. We also perform a comparison to Pb+Pb collisions pointing out that even if the collective flows have a similar magnitude the features of the matter created are different. By studying the correlation between collective flows and initial geometry, we find that the correlation decreases faster in small systems with the increase of $n$ and centrality. In particular we show that the variance of $σ_{v_{n}} / ⟨ v_{n} ⟩$ has a quite different evolution with centrality for p+Pb, so their measurement could provide some further hint about the correctness of current modelling.
Comments:
10 pages, 15 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1907.11287 [pdf]
EPJC(2020)·37 citations
03
[Submitted on 26 Jul 2019]
Low-energy bound states, resonances, and scattering of light ions
Benjamin K. Luna · T. Papenbrock
We describe bound states, resonances and elastic scattering of light ions using a $δ$ -shell potential. Focusing on low-energy data such as energies of bound states and resonances, charge radii, asymptotic normalization coefficients, effective-range parameters, and phase shifts, we adjust the two parameters of the potential to some of these observables and make predictions for the nuclear systems $d + α$ , $\mbox{$ ^3 $He}+\alpha$ , $\mbox{$ ^3 $He}+\alpha$ , $α + α$ , and $p+\mbox{$ ^{16} $O}$ . We identify relevant momentum scales for Coulomb halo nuclei and propose how to apply systematic corrections to the potentials. This allows us to quantify statistical and systematic uncertainties. We present a constructive criticism of Coulomb halo effective field theory and compute the unknown charge radius of $^{17}$ F.
Comments:
18 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1907.11345 [pdf]
PRC(2019)·16 citations
04
[Submitted on 26 Jul 2019]
Upsilon decay widths in magnetized asymmetric nuclear matter
Amruta Mishra🇮🇳 · S.P. Misra🇮🇳
The in-medium partial decay widths of $Υ (4 S) \to B B ˉ$ in magnetized asymmetric nuclear matter are studied using a field theoretic model for composite hadrons with quark (and antiquark) constituents. The medium modifications of the decay widths of $Υ (4 S)$ to $B B ˉ$ pair in magnetized matter arise due to the mass modifications of the decaying $Υ (4 S)$ as well as of the produced $B$ and $B ˉ$ mesons. The in-medium masses of the open bottom meson in magnetized nuclear matter are computed from their interactions with the nucleons and the scalar mesons within a chiral effective model. The mass modification of the $Υ (4 S)$ arises due to the medium modification of a scalar dilaton field, which is introduced in the model to simulate the gluon condensates of QCD. The charged $B^{\pm}$ mesons have additional contributions from the Landau energy levels, leading to positive shifts in their masses in the presence of a magnetic field. In the presence of an external magnetic field, there are contributions to the masses of the $B$ , $B ˉ$ mesons and $Υ (4 S)$ state (longitudinal component) due to the pseudoscalar meson-vector meson (PV) mixing ( $B - B^{*}$ , $B ˉ - B^{*} ˉ$ and $Υ (4 S) - η_{b} (4 S)$ mixings), which are also considered in the present study. The PV mixing effects are observed to be the dominant contributions to the mass shifts of these mesons, which lead to appreciable modifications in the decay widths of $Υ (4 S)$ to the neutral ( $B^{0} B^{0} ˉ$ ) and the charged ( $B^{+} B^{-}$ ) pairs in the presence of a magnetic field. These should have observable consequence in the production of open bottom mesons and bottomonium states at LHC and RHIC, where huge magnetic fields are produced in ultra-relativistic peripheral heavy ion collisions.
Comments:
29 pages, 7 figures (to be published in Int.Jour.Mod.Phys.E
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1907.11380 [pdf]
IJMPE(2022)·15 citations
05
[Submitted on 26 Jul 2019]
The effect of Confined One Gluon Exchange Potential and Instanton Induced Interaction in Nucleon-Nucleon Interaction
Raghavendra S.🇮🇳 · Vanamali C. Shastry🇮🇳 · Nilakanthan V. K.🇮🇳 · Vijaya Kumar K. B🇮🇳
The effect of Confined One Gluon Exchange Potential and Instanton Induced Interaction potential in the singlet ( $^{1} S_{0}$ ) and triplet ( $^{3} S_{1}$ ) channels for Nucleon-Nucleon interaction has been investigated in the framework of Relativistic Harmonic Model using Resonating Group Method in the adiabatic limit with Born - Oppenheimer approximation. The contributions of the different components of the interaction potentials have been analyzed.
Comments:
8 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1907.11430 [pdf]
Commun.Theor.Phys.(2020)·2 citations
06
[Submitted on 26 Jul 2019]
Probing the relativistic mean field effective NN forces for fusion of spherical colliding nuclei within a dynamical model
Maria Chushnyakova · Igor Gontchar · Natalya Khmyrova
For the first time, the precise data on the above barrier fusion (capture) cross-sections for the reactions involving spherical colliding nuclei are quantitatively analyzed using the relativistic mean-field effective interaction. The parameter sets NL1, NL2, NL3, and HS are employed. The analysis is performed within the framework of the fluctuation-dissipation model with surface friction based on the double-folding approach for the nucleus-nucleus potential. The effective interactions, as well as the resulting potentials, are confronted with the ones obtained using the M3Y NN forces. Of the four studied NN interactions, the Coulomb barrier appears for the nucleus-nucleus potentials corresponding to the NL2 and HS parameter sets when the exchange forces are added to the effective interaction. The heights and radii of the barriers obtained using these two parameter sets are very close to each other. The NL2 potential is used for analyzing the fusion cross-section data for five reactions. The results of dynamical calculations are in good agreement with the experimental data.
Comments:
7 pages, 4 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1907.11469 [pdf]
0 citations
07
[Submitted on 24 Jul 2019]
Cascade Calculations with Schematic Interactions
Levering Wolfe · Larry Zamick
In previous works we considered schematic Hamiltonians represented by simplified matrices. We defined 2 transition operators and calculated transition strengths from the ground state to all exited states. In many cases the strengths decreased nearly exponentially with excitation energy. Now we do the reverse We start with the highest energy state and calculate the cascade of transitions until the ground states is reached. On a log plot we show the average transition strength as a function of the number of energy intervals that were crossed. We give an analytic proof of exponential behavior for transition strength in the weak coupling limit for the T2 transition operator.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1907.11528 [pdf]
IJMPE(2019)·3 citations
08
[Submitted on 26 Jul 2019] (cross-list from hep-ph)
Lepton angular distributions of Drell-Yan process in pQCD and a geometric approach
Wen-Chen Chang🇹🇼 · Randall Evan McClellan🇺🇸 · Jen-Chieh Peng🇺🇸 · Oleg Teryaev🇷🇺
The lepton angular distributions of the Drell-Yan process in the fixed-target experiments are investigated by NLO and NNLO perturbative QCD. We present the calculated angular parameters $λ$ , $μ$ , $ν$ and the degree of violation of the Lam-Tung relation, $1 - λ - 2 ν$ , for the E615 experiment as well as predictions for the COMPASS experiment. Many salient features of transverse momentum and rapidity dependence could be qualitatively understood by a geometric approach.
Comments:
5 pages, 2 figures; contribution to the proceedings of the XXVII. International Workshop on Deep-Inelastic Scattering and Related Subjects (DIS2019), April 8-12, 2019,Torino, Italy
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1907.11356 [pdf]
PoS(2019)·1 citation
09
[Submitted on 26 Jul 2019] (cross-list from nucl-ex)
Single-particle shell strengths near the doubly magic nucleus $^{56}$ Ni and the $^{56}$ Ni(p, $γ$ ) $^{57}$ Cu reaction rate in explosive astrophysical burning
D. Kahl · P. J. Woods · T. Poxon-Pearson · F. M. Nunes · B. A. Brown · H. Schatz · T. Baumann · D. Bazin · J. A. Belarge · P. C. Bender · B. Elman · A. Estrade and 15 other authors
Angle-integrated cross-section measurements of the $^{56}$ Ni(d,n) and (d,p) stripping reactions have been performed to determine the single-particle strengths of low-lying excited states in the mirror nuclei pair $^{57}$ Cu- $^{57}$ Ni situated adjacent to the doubly magic nucleus $^{56}$ Ni. The reactions were studied in inverse kinematics utilizing a beam of radioactive $^{56}$ Ni ions in conjunction with the GRETINA $γ$ -array. Spectroscopic factors are compared with new shell-model calculations using a full $p f$ model space with the GPFX1A Hamiltonian for the isospin-conserving strong interaction plus Coulomb and charge-dependent Hamiltonians. These results were used to set new constraints on the $^{56}$ Ni(p, $γ$ ) $^{57}$ Cu reaction rate for explosive burning conditions in x-ray bursts, where $^{56}$ Ni represents a key waiting point in the astrophysical rp-process.
Comments:
Final version accepted and published. 5 pages, 2 figures
Subjects:
Nuclear Experiment (nucl-ex); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
1907.11665 [pdf]
PLB(2019)·19 citations

Affiliations

first authorsco-authorsvia INSPIRE