Nuclear Theory·nucl-th

Tuesday·September 28, 2021

9 papers—3 primary·6 cross-listed

04
Holographic approach to transport in dense QCD matter
Carlos Hoyos🇪🇸 · Niko Jokela🇫🇮 · Matti Järvinen🇰🇷 · Javier G. Subils🇪🇸 · Javier Tarrio🇫🇮 · Aleksi Vuorinen🇫🇮
The transport properties of dense QCD matter play a crucial role in the physics of neutron stars and their mergers, but are notoriously difficult to study with traditional quantum field theory tools. Specializing to the case of unpaired quark matter in beta equilibrium, we approach the problem through the machinery of holography, in particular the V-QCD and D3-D7 models, and derive results for the electrical and thermal conductivities and the shear and bulk viscosities. In addition we compare the bulk to shear viscosity ratio to the speed of sound and find that it violates the so-called Buchel bound. Our results differ dramatically from earlier predictions of perturbative QCD, the root causes and implications of which we analyze in detail.
↳ hep-thastro-ph.HEhep-phnucl-thPRD(2022)·37 citations
05
Cracking hadron and nuclear collisions open with ropes and string shoving in PYTHIA8
Smita Chakraborty🇸🇪
Enhancement in strangeness yields in heavy-ion collisions is regarded as one of the attributes of the Quark-Gluon Plasma (QGP) along with jet quenching and final-state collectivity. To reproduce these effects in the MC implementation of the Lund string model in \pythia, the inclusion of non-perturbative mechanisms like string shoving and rope hadronization is crucial. In this proceeding, we discuss our latest implementation of these mechanisms and the preliminary results for the strangeness enhancement in high-multiplicity p-p, p-Pb and Xe-Xe. We conclude with remarks on the ongoing development of the model.
↳ hep-phnucl-thSciPost Phys.Proc.(2022)·3 citations
06
Correlation Integral vs. second order Factorial Moments and an efficient computational technique
F. K. Diakonos🇬🇷 · A. S. Kapoyannis🇬🇷
We develop a mapping between the factorial moments of the second order $F_{2}$ and the correlation integral $C$ . We formulate a fast computation technique for the evaluation of both, which is more efficient, compared to conventional methods, for data containing number of pairs per event which is lower than the estimation points. We find the effectiveness of the technique to be more prominent as the dimension of the embedding space increases. We are able to analyse large amount of data in short computation time and access very low scales in $C$ or extremely high partitions in $F_{2}$ . The technique is an indispensable tool for detecting a very weak signal hidden in strong noise.
↳ hep-phnlin.CDnucl-thphysics.comp-phEPJC(2022)·7 citations
07
The masses of hadrons in the chiral symmetry restored vacuum
Jisu Kim🇰🇷 · Su Houng Lee🇰🇷
We calculate the masses of the vector and axial-vector mesons as well as the nucleon and the delta resonance in the chiral symmetry restored vacuum. This is accomplished by separating the quark operators appearing in the QCD sum rules for these hadrons into the chiral symmetric and symmetry breaking parts depending on the contributions of the fermion zero modes. We then extract the vacuum expectation values of all the separated parts of the quark operators using the QCD sum rule relations for these hadrons with their vacuum masses and widths. By taking the chiral symmetry breaking parts to be zero while keeping the symmetric operators to their vacuum values, we obtain the chiral symmetric part of the hadron masses. We find that the masses of chiral partners, such as the $(ρ, a_{1})$ and $(K^{*}, K_{1})$ , become degenerate to values between 500 and 600 MeV in the chiral symmetry restored vacuum, while parity partners $(ω, f_{1})$ that are chiral partners only in the limit where the disconnected diagrams are neglected remain non-degenerate with masses $(655, 1060)$ MeV, respectively. The masses of the nucleon and the Delta are also found to reduce to about 500 and 600 MeV, respectively, in the chiral symmetric vacuum. This shows that while chiral symmetry breaking is responsible for the mass difference between chiral partner, both the meson and baryon retain non-trivial fraction of their masses in the chiral symmetry restored vacuum.
↳ hep-phnucl-exnucl-thPRD(2022)·21 citations
08
Isobaric Multiplet Mass Equation for $A \leq 71$ Revisited
Yi Hua Lam🇫🇷 · Bertram Blank🇫🇷 · Nadezda A. Smirnova🇫🇷 · Jean Bernard Bueb🇫🇷 · Maria Susai Antony🇫🇷
Accurate mass determination of short-lived nuclides by Penning-trap spectrometers and progress in the spectroscopy of proton-rich nuclei have triggered renewed interest in the isobaric multiplet mass equation (IMME). The energy levels of the members of $T = 1/2, 1, 3/2,$ and 2 multiplets and the coefficients of the IMME are tabulated for $A \leq 71$ . The new compilation is based on the most recent mass evaluation (AME2011) and it includes the experimental results on energies of the states evaluated up to end of 2011. Taking into account the error bars, a significant deviation from the quadratic form of the IMME for the $A = 9, 35$ quartets and the $A = 32$ quintet is observed.
↳ nucl-exnucl-thAtom.Data Nucl.Data Tabl.(2013)·52 citations
09
New insights into the nucleon's electromagnetic structure
Yong-Hui Lin🇩🇪 · Hans-Werner Hammer🇩🇪 · Ulf-G. Meißner🇩🇪
We present a combined analysis of the electromagnetic form factors of the nucleon in the space- and timelike regions using dispersion theory. Our framework provides a consistent description of the experimental data over the full range of momentum transfer, in line with the strictures from analyticity and unitarity. The statistical uncertainties of the extracted form factors are estimated using the bootstrap method, while systematic errors are determined from variations of the spectral functions. We also perform a high-precision extraction of the nucleon radii and find good agreement with previous analyses of spacelike data alone. For the proton charge radius, we find $r_{E}^{p} = 0.84 0_{- 0.002}^{+ 0.003}_{- 0.002}^{+ 0.002}$ ~fm, where the first error is statistical and the second one is systematic. The Zemach radius and third moment are in agreement with Lamb shift measurements and hyperfine splittings. The combined data set of space- and timelike data disfavors a zero crossing of $μ_{p} G_{E}^{p} / G_{M}^{p}$ in the spacelike region. Finally, we discuss the status and perspectives of modulus and phase of the form factors in the timelike region in the context of future experiments as well as the onset of perturbative QCD.
↳ hep-phhep-exhep-latnucl-ex+1PRL(2022)·131 citations

Affiliations

first authorsco-authorsvia INSPIRE

Holographic approach to transport in dense QCD matter

Cracking hadron and nuclear collisions open with ropes and string shoving in PYTHIA8

Correlation Integral vs. second order Factorial Moments and an efficient computational technique

The masses of hadrons in the chiral symmetry restored vacuum

Isobaric Multiplet Mass Equation for A≤71 Revisited

New insights into the nucleon's electromagnetic structure

Affiliations

Isobaric Multiplet Mass Equation for $A \leq 71$ Revisited