Nuclear Theory·nucl-th

Friday·March 16, 2018

11 papers—3 primary·8 cross-listed

01
$ΛΛ$ pairing in multi-strange hypernuclei
H. Güven🇹🇷 · K. Bozkurt🇹🇷 · E. Khan🇫🇷 · J. Margueron🇺🇸
Multi-strange Ca, Sn and Pb hypernuclei with $ΛΛ$ pairing interaction are investigated within the Hartree-Fock-Bogoliubov approach. The unknown $ΛΛ$ pairing strength is calibrated to match with the maximal value for the prediction of the $Λ$ pairing gap in uniform matter for densities and isospin asymmetries equivalent to those existing in multi- $Λ$ hypernuclei. In this way, we provide an upper bound for the prediction of the $Λ$ pairing gap and its effects in hypernuclei. The condensation energy is predicted to be about 3~MeV as a maximum value, yielding small corrections on density distributions and shell structure. In addition, conditions on both Fermi energies and orbital angular momenta are expected to quench the nucleon- $Λ$ pairing for most of hypernuclei.
nucl-thPRC(2018)·17 citations
02
Theoretical study of the Lambda(1405) resonance in Xi_b^0 -> D^0 pi Sigma decay
Kenta Miyahara🇯🇵 · Tetsuo Hyodo🇯🇵
We study the mechanism of the weak decay process of Xi_b^0 into D^0 with a meson-baryon pair. It is shown that the dominant component of the prompt weak decay produces the meson-baryon pair with the spectator strange quark being transferred to the baryon, so that the Kbar N channel is absent. Subsequent final state interaction then reflects the pi Sigma originated Lambda(1405) formation amplitude, which has been difficult to access in previous experimental studies. We predict the line shapes of the pi Sigma invariant mass distribution using a realistic chiral meson-baryon amplitude for the final state interaction. It is shown that the interference between the direct and the rescattering contributions can strongly distort the peak structure of the Lambda(1405) in the mass distribution. This indicates the necessity of a detailed investigation of the reaction mechanism in order to extract the Lambda(1405) property in the pi Sigma mass distribution.
nucl-thhep-phPRC(2018)·11 citations
03
Effective field theory for collective rotations and vibrations of triaxially deformed nuclei
Q. B. Chen · N. Kaiser · Ulf-G. Meißner · J. Meng
The effective field theory (EFT) for triaxially deformed even-even nuclei is generalized to include the vibrational degrees of freedom. The pertinent Hamiltonian is constructed up to next-to-leading order. The leading order part describes the vibrational motion, and the NLO part couples rotations to vibrations. The applicability of the EFT Hamiltonian is examined through the description of the energy spectra of the ground state bands, $γ$ -bands, and $K = 4$ bands in the $^{108, 110, 112}$ Ru isotopes. It is found that by taking into account the vibrational degrees of freedom, the deviations for high-spin states in the $γ$ -band observed in the EFT with only rotational degrees of freedom disappear. This supports the importance of including vibrational degrees of freedom in the EFT formulation for the collective motion of triaxially deformed nuclei.
nucl-thPRC(2018)·9 citations
04
Continuity of vortices from the hadronic to the color-flavor locked phase in dense matter
Mark G. Alford🇺🇸 · Gordon Baym🇺🇸 · Kenji Fukushima🇯🇵 · Tetsuo Hatsuda🇯🇵 · Motoi Tachibana🇯🇵
We study how vortices in dense superfluid hadronic matter can connect to vortices in superfluid quark matter, as in rotating neutron stars, focusing on the extent to which quark-hadron continuity can be maintained. As we show, a singly quantized vortex in three-flavor symmetric hadronic matter can connect smoothly to a singly quantized non-Abelian vortex in three-flavor symmetric quark matter in the color-flavor locked (CFL) phase, without the necessity for boojums appearing at the transition.
↳ hep-phnucl-thPRD(2019)·49 citations
05
Limiting fragmentation in high-energy nuclear collisions at the CERN Large Hadron Collider
Pragati Sahoo🇮🇳 · Pooja Pareek🇮🇳 · Swatantra Kumar Tiwari🇮🇳 · Raghunath Sahoo🇮🇳
The hypothesis of limiting fragmentation (LF) or it is called otherwise recently, as extended longitudinal scaling, is an interesting phenomena in high energy multiparticle production process. This paper discusses about different regions of phase space and their importance in hadron production, giving special emphasis on the fragmentation region. Although it was conjectured as a universal phenomenon in high energy physics, with the advent of higher center-of-mass energies, it has become prudent to analyse and understand the validity of such hypothesis in view of the increasing inelastic nucleon-nucleon cross-section ( $σ_{in}$ ). In this work, we revisit the phenomenon of limiting fragmentation for nucleus-nucleus (A+A) collisions in the pseudorapidity distribution of charged particles at various energies. We use energy dependent $σ_{in}$ to transform the charged particle pseudorapidity distributions ( $d N_{c h}^{AA} / d η$ ) into differential cross-section per unit pseudorapidity ( $d σ^{AA} / d η$ ) of charged particles and study the phenomenon of LF. We find that in $d σ^{AA} / d η$ LF seems to be violated at LHC energies while considering the energy dependent $σ_{in}$ . We also perform a similar study using A Multi-Phase Transport (AMPT) Model with string melting scenario and also find that LF is violated at LHC energies.
↳ hep-phhep-exnucl-exnucl-thPRC(2019)·11 citations
06
$P_{c}$ -like pentaquarks in hidden strange sector
Hongxia Huang · Jialun Ping
Analogous to the work of hidden charm molecular pentaquarks, we study possible hidden strange molecular pentaquarks composed of $Σ$ (or $Σ^{*}$ ) and $K$ (or $K^{*}$ ) in the framework of quark delocalization color screening model. Our results suggest that the $Σ K$ , $Σ K^{*}$ and $Σ^{*} K^{*}$ with $I J^{P} = \frac{1}{2} \frac{1}{2}^{-}$ and $Σ K^{*}$ , $Σ^{*} K$ and $Σ^{*} K^{*}$ with $I J^{P} = \frac{1}{2} \frac{3}{2}^{-}$ are all resonance states by coupling the open channels. The molecular pentaquark $Σ^{*} K$ with quantum numbers $I J^{P} = \frac{1}{2} \frac{3}{2}^{-}$ can be seen as a strange partner of the LHCb $P_{c} (4380)$ state, and it can be identified as the nucleon resonance $N^{*} (1875)$ listed in PDG. The $Σ K^{*}$ with quantum numbers $I J^{P} = \frac{1}{2} \frac{3}{2}^{-}$ can be identified as the $N^{*} (2100)$ , which was experimentally observed in the $ϕ$ photo-production.
↳ hep-phnucl-thPRD(2018)·28 citations
07
Dispersion relation formalism for the two-photon exchange correction to elastic muon-proton scattering: elastic intermediate state
Oleksandr Tomalak🇩🇪 · Marc Vanderhaeghen🇩🇪
We evaluate the two-photon exchange correction to the unpolarized cross section in the elastic muon-proton scattering within dispersion relations. One of the six independent invariant amplitudes requires a subtraction. We fix the subtraction function to the model estimate of the full two-photon exchange at one of three MUSE beam energies and make a prediction for the two other energies. Additionally, we present single and double polarization observables accounting for the lepton mass.
↳ hep-phnucl-exnucl-thEPJC(2018)·38 citations
08
Effective field theory for the nucleon-quarkonium interaction
Jaume Tarrús Castellà🇪🇸 · Gastão Krein🇧🇷
We develop an effective field theory approach for the $S$ -wave quarkonium-nucleon system. We adopt a natural power counting equivalent to Weinberg's power counting in nucleon-nucleon effective field theories and compute the quarkonium-nucleon potential, scattering length and effective range up to $O (m_{π}^{3} / Λ_{χ}^{3})$ accuracy, including the full light-quark mass dependence. We compare our results with lattice QCD studies of quarkonium-nucleon system, obtain an estimation of the leading order quarkonium-nucleon contact term and determine the $J / ψ$ and $η_{c}$ chromopolarizabilities.
↳ hep-phnucl-thPRD(2018)·51 citations
09
Distribution of Stress Tensor around Static Quark--Anti-Quark from Yang-Mills Gradient Flow
Ryosuke Yanagihara🇯🇵 · Takumi Iritani🇯🇵 · Masakiyo Kitazawa🇯🇵 · Masayuki Asakawa🇯🇵 · Tetsuo Hatsuda🇯🇵
The spatial distribution of the stress tensor around the quark--anti-quark ( $Q Q ˉ$ ) pair in SU(3) lattice gauge theory is studied. The Yang-Mills gradient flow plays a crucial role to make the stress tensor well-defined and derivable from the numerical simulations on the lattice. The resultant stress tensor with a decomposition into local principal axes shows, for the first time, the detailed structure of the flux tube along the longitudinal and transverse directions in a gauge invariant manner. The linear confining behavior of the $Q Q ˉ$ potential at long distances is derived directly from the integral of the local stress tensor.
↳ hep-lathep-phnucl-thPLB(2019)·45 citations
10
Positrons at JLab - Advancing Nuclear Science in Hall B
Volker D. Burkert🇺🇸
In this talk I address two high impact physics programs that require the use of polarized and unpolarized positron beams in addition to using electron beams of the same energy. First, I address what will be gained from using positron beams in addition to electron beams in the extraction of the Compton Form Factors (CFFs) and generalized parton distributions (GPDs) from Deeply Virtual Compton Scattering (DVCS) on a proton target. As a second high impact science program I discuss an experimental scenario using unpolarized positrons to measure elastic scattering on protons in an effort to determine definitively the 2-photon exchange contributions in order to resolve a longstanding discrepancy in the determination of the proton's electric and magnetic form factors.
↳ nucl-exhep-exnucl-thAIP Conf.Proc.(2018)·0 citations
11
Practical considerations for measuring global spin alignment of vector mesons in relativistic heavy ion collisions
A. H. Tang · B. Tu · C. S. Zhou
Global spin alignment of vector mesons is a sensitive probe of system vorticity and particle production mechanism in relativistic heavy ion collisions. The measurement of global spin alignment is gaining increasing interest and deserves careful considerations. In this paper, we lay out a few practical issues that need to be taken care of when measuring global spin alignment of vector mesons. They are, the correction for event plane resolution, reconciling measurements made with different event planes, the correction for the effect of finite acceptance in pseudorapidity, and the consideration for measuring the azimuthal angle dependence. Insights and methodologies offered in this paper will help experiments to measure the global spin alignment properly and accurately.
↳ nucl-exnucl-thPRC(2018)·34 citations

Affiliations

first authorsco-authorsvia INSPIRE