Nuclear Theory·nucl-th

Monday·October 1, 2018

8 papers—4 primary·4 cross-listed

01
Cracking the difference of estimating heavy quark transport coefficients in a Quark-Gluon Plasma
Yingru Xu🇺🇸 · Steffen A. Bass🇺🇸 · Pierre Moreau🇩🇪 · Taesoo Song🇩🇪 · Marlene Nahrgang🇫🇷 · Elena Bratkovskaya🇩🇪 · Pol Gossiaux🇫🇷 · Jorg Aichelin🇫🇷 · Shanshan Cao🇺🇸 · Vincenzo Greco🇮🇹 · Gabriele Coci🇮🇹 · Klaus Werner🇫🇷
Heavy flavor observables provide valuable information on the properties of the hot and dense Quark-Gluon Plasma (QGP) created in ultra-relativistic nucleus-nucleus collisions. Various microscopic models have successfully described many of the observables associated with its formation. Their transport coefficients differ, however, due to different assumptions about the underlying interaction of the heavy quarks with the plasma constituents, different initial geometries and formation times, different hadronization processes and a different time evolution of the QGP. In this study we present the transport coefficients of all these models and investigate systematically how some of these assumptions influence the heavy quark properties at the end of the QGP expansion. For this purpose we impose on these models the same initial condition and the same model for the QGP expansion and show that both have considerable influence on $R_{AA}$ and $v_{2}$ .
nucl-thPRC(2019)·75 citations
02
Parity-Violating Three Nucleon Interactions at Low Energies and Large- $N_{C}$
Jared Vanasse🇺🇸
The parity-violating (PV) nucleon-nucleon ( $N N$ ) interaction in the three-nucleon system is investigated using pionless effective field theory ( $EFT (/ π)$ ). This work shows that a next-to-leading order (NLO) PV three-body force is necessary in contradiction with a previous claim [Griesshammer and Schindler in Eur. Phys. J. A 46, 73 (2010)]. Including three-body $P$ to $D$ -wave transitions PV three-nucleon observables are calculated to higher energies than previously considered. Using the recent large- $N_{C}$ analysis of the PV $N N$ interaction in $EFT (/ π)$ the current understanding of low energy PV few-body measurements is reassessed. The recent measurement of the asymmetry $A_{γ}$ in $n p \to d γ$ from the NPDGamma collaboration [D. Blyth et al. (NPDGamma), Phys. Rev. Lett. 121, 242002 (2018)], gives the value $g_{4}^{(N_{C}^{- 1})} = (- 1.4 \pm 0.63 (s t a t .) \pm 0.09 (sy s t .)) \times 1 0^{- 10} MeV^{- 1}$ for a next-to-next-to-leading order (N $^{2}$ LO) in large- $N_{C}$ low energy constant (LEC). Using the large- $N_{C}$ hierarchy of LECs the sizes of the leading order (LO) in large- $N_{C}$ LECs are estimated using an experimental bound on a parity violating asymmetry in $p d$ scattering at $E_{lab} = 15$ MeV and a measurement of $pp$ scattering at $E_{lab} = 13.6$ MeV. Comparing the size of the resulting LO in large- $N_{C}$ LECs to the N $^{2}$ LO in large- $N_{C}$ LEC $g_{4}^{(N_{C}^{- 1})}$ shows they are roughly the same size in contradiction with current large- $N_{C}$ counting.
nucl-thPRC(2019)·10 citations
03
Impact of the ionization of the atomic shell on the lifetime of the 229mTh isomer
F. F. Karpeshin · M.B.Trzhaskovskaya
Recent experimental data are analyzed, concerning the half-lives of the 229mTh isomer in neutral atoms and various ions. Calculation is performed on the united platform of interplay of traditional and subthreshold resonance conversion. General agreement with experiment is obtained in the cases of Th I and Th III, a prediction is made concerning half-life in Th IV. Most critical is the case of Th II, where experimental data can be explained by interplay of various factors. A new physics is proposed, based on dependence of the nuclear lifetime on the ambient conditions, such as atmospheric pressure. This must be taken into account in future experiments and their interpretation.
nucl-thNPA(2018)·12 citations
04
Fast resonance decays in nuclear collisions
Aleksas Mazeliauskas🇩🇪 · Stefan Floerchinger🇩🇪 · Eduardo Grossi🇩🇪 · Derek Teaney🇺🇸
In the context of ultra-relativistic nuclear collisions, we present a fast method for calculating the final particle spectra after the direct decay of resonances from a Cooper-Frye integral over the freeze-out surface. The method is based on identifying components of the final particle spectrum that transform in an irreducible way under rotations in the fluid-restframe. Corresponding distribution functions can be pre-computed including all resonance decays. Just a few of easily tabulated scalar functions then determine the Lorentz invariant decay spectrum from each space-time point, and simple integrals of these scalar functions over the freeze-out surface determine the final decay products. This by-passes numerically costly event-by-event calculations of the intermediate resonances. The method is of considerable practical use for making realistic data to model comparisons of the identified particle yields and flow harmonics, and for studying the viscous corrections to the freeze-out distribution function.
nucl-thhep-phEPJC(2019)·48 citations
05
Jet shape modifications in holographic dijet systems
Jasmine Brewer🇺🇸 · Andrey Sadofyev🇺🇸 · Wilke van der Schee🇺🇸
We present a coherent model that combines jet production from perturbative QCD with strongly-coupled jet-medium interactions described in holography. We use this model to study the modification of an ensemble of jets upon propagation through a quark-gluon plasma resembling central heavy ion collisions. Here the modification of the dijet asymmetry depends strongly on the subleading jet width, which can therefore be an important observable for studying jet-medium interactions. We furthermore show that the modification of the shape of the leading jet is relatively insensitive to the dijet asymmetry, whereas the subleading jet shape modification is much larger for more imbalanced dijets. Finally, we compare the results of our holographic model to a recent CMS measurement.
↳ hep-phhep-thnucl-exnucl-thPLB(2021)·23 citations
06
Weak-Interaction Tests via Precision Superallowed $β$ -Decay Studies at TRIUMF
Kyle G. Leach🇺🇸 · Jason D. Holt🇨🇦
Superallowed $β$ -decay studies provide some of the best constraints on the possibility of additional quark generations, as well as limits on exotic currents in the weak interaction. The three experimental quantities that are required for performing these tests using $0^{+} \to 0^{+}$ nuclear decays (branching ratio, half-life, and $Q$ -value) can all be measured to high-precision with rare-isotope beams at the TRIUMF-ISAC facility in Vancouver, Canada. This proceeding presents a brief outline of the general experimental techniques used at TRIUMF over the past 15 years, as well as recent theoretical advances towards {\it ab-initio} isospin-symmetry-breaking corrections to superallowed nuclear decays.
↳ nucl-exnucl-th3 citations
07
Form factors for pions couplings to constituent quarks under weak magnetic field
Fabio L. Braghin🇧🇷 · Willian F. de Sousa🇧🇷
By considering a one loop background field method for a nonperturbative one gluon exchange between quarks, leading electromagnetic form factors of pion couplings to constituent quarks are derived by means of from a large quark and gluon effective masses expansion. With this calculation the leading anisotropic corrections induced by a weak magnetic field for the pion-constituent quark form factors are obtained. Besides that, few effective couplings which emerge only due to the weak magnetic field that break chiral and isospin symmetry are also found. Numerical estimations for these magnetic field corrections are presented for two different nonperturbative gluon propagators. All of these corrections are ultraviolet finite and their relative values are found to be of order of $(e B_{0} / M^{*}^{2})^{n}$ being $n = 1$ for the vector and axial pion couplings and $n = 2$ for the pseudoscalar and scalar ones. The corresponding anisotropic corrections to the Strong averaged quadratic radii in the plane perpendicular to the magnetic field are also calculated as functions of the quark effective mass.
↳ hep-phnucl-thJ.Phys.G(2020)·9 citations
08
Binding-energy independence of reduced single particle strengths derived from $(p, d)$ reactions
Y.P. Xu · D.Y. Pang · X.Y. Yun · C. Wen · C.X. Yuan · J.L. Lou
An overall reduction factor (ORF) is introduced for studying the quenching of single particle strengths through nucleon transfer reactions. The ORF includes contributions of all the probed bound states of the residual nucleus in a transfer reaction and permits a proper comparison with results of inclusive knockout reactions. A systematic analysis is made with 103 sets of angular distribution data of $(p, d)$ reactions on 21 even-even targets with atomic mass numbers from 8 to 56 using the consistent three-body model reaction methodology proposed in [J. Lee, J.A. Tostevin, B.A. Brown, et al., Phys. Rev. C 73, 044608 (2006)]. The extracted ORFs are found to be nearly independent on the nuclear isospin asymmetry, which is different from the systematics of inclusive knockout reactions but is consistent with the recent measurement of $(d, t)$ , $(d, 3 H e)$ , $(p, 2 p)$ , and $(p, p n)$ reactions on nitrogen and oxygen isotopes and \textit{ab initio} calculations.
↳ nucl-exnucl-th0 citations

Affiliations

first authorsco-authorsvia INSPIRE