Ground State Masses Research Articles

Isgur–Wise function and a new approach to potential model

Considering the Cornell potential [Formula: see text], we have revisited the Dalgarno’s method of perturbation by incorporating two scales [Formula: see text] and [Formula: see text] as integration limit so that the perturbative procedure can be improved in a potential model. With the improved version of the wave function the ground state masses of the heavy–light mesons [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] are computed. The slopes and curvatures of the form factors of semileptonic decays of heavy–light mesons in both HQET limit and finite mass limit are calculated and compared with the available data.

The sigma meson from QCD sum rules for large- $$N_c$$ N c Regge spectra

The QCD sum rules in the large-$N_c$ limit for the light non-strange vector, axial and scalar mesons are considered assuming a string-like linear spectrum for the radially excited states. We propose a improved method for combined analysis of these channels that gives a reasonable description of the observed spectrum. In the vector-axial case, fixing the pion decay constant and the gluon condensate we obtain more or less physical values for the masses of ground states and the quark condensate. Thus a typical need for this method to fix the mass of some ground state is overcome. Using in the scalar channel the values of presumably universal slope of radial trajectories and the quark condensate obtained in the vector-axial channel, we find that, in contrast to some strong claims in the literature, a prediction of light scalar state with a mass close to the mass of $f_0(500)$ seems to be natural in the considered approach and may follow in a natural way from the Regge phenomenology.

Minimal mass non-scattering solutions of the focusing <i>L</i><sup>2</sup>-critical Hartree equations with radial data

We prove that for the Cauchy problem of focusing \begin{document}$L^2$\end{document} -critical Hartree equations with spherically symmetric \begin{document}$H^1$\end{document} data in dimensions \begin{document}$3$\end{document} and \begin{document}$4$\end{document} , the global non-scattering solution with ground state mass must be a solitary wave up to symmetries of the equation. The approach is a linearization analysis around the ground state combined with an in-out spherical wave decomposition technique.

Quantum vacuum effects for a massive Bosonic string in background B-field

ما در این مقاله اثر کازیمیر را برای مدل ریسمان بوزونی جرم ‌دار کشیده شده میان دو غشا در فضای تخت و در حضور یک میدان پس زمینه پاد متقارن بررسی خواهیم کرد. این مدل، تعمیمی است از مسئله ریسمان بی جرم در میدان پس زمینه، که مدلی شناخته شده در چارچوب نظریه ریسمان است. برای یافتن انرژی کازیمیر، هامیلتونی کانونی ریسمان را به صورت یک برهم نهی از مدهای نوسانگر هماهنگ ساده به دست خواهیم آورد. پس از کوانتش، این مدهای نوسانی را می‌توان با نوسانگرهای هماهنگ کوانتومی هم ارز دانست. در نتیجه می‌توان انرژی حالت پایه کوانتومی (خلا) ریسمان را به صورت جمعی از انرژی‌های تراز صفر کوانتومی این نوسانگرهای هماهنگ نمایش داد. بدین سان انرژی خلا به صورت یک جمع نامتناهی به دست خواهد آمد که با منظم سازی آن، انرژی کازیمیر را به صورت تابعی از میدان پس زمینه و پارامتر جرمی ریسمان خواهیم یافت. با تعبیر این انرژی کازیمیر به عنوان جرم حالت پایه ریسمان، جمله تصحیحی وابسته به میدان پس زمینه، برای حالت پایه ریسمان خواهیم یافت و نشان خواهیم داد که برای میدان‌های زمینه بزرگ، حالت پایه ریسمان حاوی ذراتی حقیقی (ناتکیونی) خواهد بود.

Excited State Mass Spectra of Ω0c Baryon

We have calculated the radial and orbital excited states of singly charmed baryon Oc using the Hypercentral Constituent Quark Model (hCQM). The confinement potential is assumed as coulomb plus power potential (CPPV). The ground state and excited state masses are determined with and with out first order correction to the potential. Furthermore, we plot graph between Mass(M) → Potential Index(v). Our calculated results are in good agreement with experimental and other theoretical predictions.

Excited state mass spectra of doubly heavy baryons $${\Omega _{cc}}$$ Ω c c , $${\Omega _{bb}}$$ Ω b b , and $${\Omega _{bc}}$$ Ω b c

We discuss the mass spectrum of $$\Omega $$ baryon with two heavy quarks and one light quark (ccs, bbs, and bcs). The main goal of the paper is to calculate the ground state masses and after that, the positive and negative parity excited states masses are also obtained within a hypercentral constituent quark model, using Coulomb plus linear potential framework. We also added a first order correction to the potential. The mass spectra up to 5S for radial excited states and 1P–5P, 1D–4D, and 1F–2F states for orbital excited states are computed for $$\Omega _{cc}$$ , $$\Omega _{bb}$$ , and $$\Omega _{bc}$$ baryons. Our obtained results are compared with other theoretical predictions, which could be a useful complementary tool for the interpretation of experimentally unknown heavy baryon spectra. The Regge trajectory is constructed in both the ( $$n_r$$ , $$M^{2}$$ ) and the (J, $$M^{2}$$ ) planes for $$\Omega _{cc}$$ , $$\Omega _{bb}$$ , and $$\Omega _{bc}$$ baryons and their slopes and intercepts are also determined. Magnetic moments of doubly heavy $$\Omega '$$ s are also calculated.

Excitations of strange bottom baryons

The ground state and first excited state masses of Omega(b) and Omega(bb) baryons are calculated in lattice QCD using dynamical 2+1 flavour gauge fields. A set of baryon operators employing different combinations of smeared quark fields was used in the framework of the variational method. Results for radial excitation energies were confirmed by carrying out a supplementary multiexponential fitting analysis. Comparison is made with quark model calculations.

Isobaric multiplet mass equation in theA=31,T=3/2quartets

The observed mass excesses of analog nuclear states with the same mass number $A$ and isospin $T$ can be used to test the isobaric multiplet mass equation (IMME), which has, in most cases, been validated to a high degree of precision. A recent measurement [Kankainen et al., Phys. Rev. C 93 041304(R) (2016)] of the ground-state mass of $^{31}$Cl led to a substantial breakdown of the IMME for the lowest $A = 31, T = 3/2$ quartet. The second-lowest $A = 31, T = 3/2$ quartet is not complete, due to uncertainties associated with the identity of the $^{31}$S member state. Using a fast $^{31}$Cl beam implanted into a plastic scintillator and a high-purity Ge $\gamma$-ray detection array, $\gamma$ rays from the $^{31}$Cl$(\beta\gamma)$$^{31}$S sequence were measured. Shell-model calculations using USDB and the recently-developed USDE interactions were performed for comparison. Isospin mixing between the $^{31}$S isobaric analog state (IAS) at 6279.0(6) keV and a nearby state at 6390.2(7) keV was observed. The second $T = 3/2$ state in $^{31}$S was observed at $E_x = 7050.0(8)$ keV. Isospin mixing in $^{31}$S does not by itself explain the IMME breakdown in the lowest quartet, but it likely points to similar isospin mixing in the mirror nucleus $^{31}$P, which would result in a perturbation of the $^{31}$P IAS energy. USDB and USDE calculations both predict candidate $^{31}$P states responsible for the mixing in the energy region slightly above $E_x = 6400$ keV. The second quartet has been completed thanks to the identification of the second $^{31}$S $T = 3/2$ state, and the IMME is validated in this quartet.

The decay energy of the pure s-process nuclide 123 Te

Abstract A direct and high-precision measurement of the mass difference of 123 Te and 123 Sb has been performed with the Penning-trap mass spectrometer SHIPTRAP using the recently introduced phase-imaging ion-cyclotron-resonance technique. The obtained mass difference is 51.912 ( 67 ) keV / c 2 . Using the masses of the neutral ground states and the energy difference between the ionic states an effective half-life of 123 Te has been estimated for various astrophysical conditions. A dramatic influence of the electron capture process on the decay properties of 123 Te in hot stellar conditions has been discussed.

Nuclear ground-state masses and deformations: FRDM(2012)

We tabulate the atomic mass excesses and binding energies, ground-state shell-plus-pairing corrections, ground-state microscopic corrections, and nuclear ground-state deformations of 9318 nuclei ranging from 16O to A=339. The calculations are based on the finite-range droplet macroscopic and the folded-Yukawa single-particle microscopic nuclear-structure models, which are completely specified. Relative to our FRDM(1992) mass table in Möller et al. (1995), the results are obtained in the same model, but with considerably improved treatment of deformation and fewer of the approximations that were necessary earlier, due to limitations in computer power. The more accurate execution of the model and the more extensive and more accurate experimental mass data base now available allow us to determine one additional macroscopic-model parameter, the density-symmetry coefficient L, which was not varied in the previous calculation, but set to zero. Because we now realize that the FRDM is inaccurate for some highly deformed shapes occurring in fission, because some effects are derived in terms of perturbations around a sphere, we only adjust its macroscopic parameters to ground-state masses.The values of ten constants are determined directly from an optimization to fit ground-state masses of 2149 nuclei ranging from 16O to 106265Sg and 108264Hs. The error of the mass model is 0.5595 MeV for the entire region of nuclei included in the adjustment, but is only 0.3549 MeV for the region N≥65.We also provide masses in the FRLDM, which in the more accurate treatments now has an error of 0.6618 MeV, with 0.5181 MeV for nuclei with N≥65, both somewhat larger than in the FRDM. But in contrast to the FRDM, it is suitable for studies of fission and has been extensively so applied elsewhere, with FRLDM(2002) constants. The FRLDM(2012) fits 31 fission-barrier heights from 70Se to 252Cf with a root-mean-square deviation of 1.052 MeV.

Resonances above the proton threshold inSi26

$^{26}\mathrm{Al}$ remains an intriguing target for observational $\ensuremath{\gamma}$-ray astronomy, thanks to its characteristic decay. The $^{25}\mathrm{Al}(p,\ensuremath{\gamma})^{26}\mathrm{Si}$ reaction is the crucial link in a sequence that bypasses the production of the observable $^{26}\mathrm{Al}^{g}$ in favor of the short-lived isomeric state; determining its astrophysical reaction rate across a range of stellar environments has been the focus of many studies. A reanalysis of previous work, utilizing recent improvements in excitation energies and ground state masses, is presented to reduce the ambiguities in the literature and provide focus to future measurements.

General Description of Fission Observables: GEF Model Code

The GEF (“GEneral description of Fission observables”) model code is documented. It describes the observables for spontaneous fission, neutron-induced fission and, more generally, for fission of a compound nucleus from any other entrance channel, with given excitation energy and angular momentum. The GEF model is applicable for a wide range of isotopes from Z = 80 to Z = 112 and beyond, up to excitation energies of about 100 MeV. The results of the GEF model are compared with fission barriers, fission probabilities, fission-fragment mass- and nuclide distributions, isomeric ratios, total kinetic energies, and prompt-neutron and prompt-gamma yields and energy spectra from neutron-induced and spontaneous fission. Derived properties of delayed neutrons and decay heat are also considered.The GEF model is based on a general approach to nuclear fission that explains a great part of the complex appearance of fission observables on the basis of fundamental laws of physics and general properties of microscopic systems and mathematical objects. The topographic theorem is used to estimate the fission-barrier heights from theoretical macroscopic saddle-point and ground-state masses and experimental ground-state masses. Motivated by the theoretically predicted early localisation of nucleonic wave functions in a necked-in shape, the properties of the relevant fragment shells are extracted. These are used to determine the depths and the widths of the fission valleys corresponding to the different fission channels and to describe the fission-fragment distributions and deformations at scission by a statistical approach. A modified composite nuclear-level-density formula is proposed. It respects some features in the superfluid regime that are in accordance with new experimental findings and with theoretical expectations. These are a constant-temperature behaviour that is consistent with a considerably increased heat capacity and an increased pairing condensation energy that is consistent with the collective enhancement of the level density. The exchange of excitation energy and nucleons between the nascent fragments on the way from saddle to scission is estimated according to statistical mechanics. As a result, excitation energy and unpaired nucleons are predominantly transferred to the heavy fragment in the superfluid regime. This description reproduces some rather peculiar observed features of the prompt-neutron multiplicities and of the even-odd effect in fission-fragment Z distributions. For completeness, some conventional descriptions are used for calculating pre-equilibrium emission, fission probabilities and statistical emission of neutrons and gamma radiation from the excited fragments. Preference is given to simple models that can also be applied to exotic nuclei compared to more sophisticated models that need precise empirical input of nuclear properties, e.g. spectroscopic information.The approach reveals a high degree of regularity and provides a considerable insight into the physics of the fission process. Fission observables can be calculated with a precision that complies with the needs for applications in nuclear technology without specific adjustments to measured data of individual systems. The GEF executable runs out of the box with no need for entering any empirical data. This unique feature is of valuable importance, because the number of systems and energies of potential significance for fundamental and applied science will never be possible to be measured. The relevance of the approach for examining the consistency of experimental results and for evaluating nuclear data is demonstrated.

Charmed baryon spectroscopy and light flavor symmetry from lattice QCD

We determine the ground state and first excited state masses of singly and doubly charmed spin 1/2 and 3/2 baryons with positive and negative parity. Configurations with $N_f=2+1$ non-perturbatively improved Wilson-clover fermions were employed, with the same quark action also being used for the valence quarks, including the charm. The spectrum is calculated for pion masses in the range $M_\pi \sim 259-460$ MeV at a lattice spacing $a\sim 0.075$ fm. Finite volume effects are studied comparing lattices with two different linear spatial extents ($1.8\,{\rm fm}$ and $2.4\,{\rm fm}$). The physical point is approached from the SU(3) limit keeping the flavour averaged light quark mass fixed. The baryon masses are extrapolated using expansions in the strange-light quark mass difference. Most particles fall into the expected SU(3) multiplets with well constrained extrapolations, the exceptions having a possibly more complex internal structure. Overall agreement is found with experiment for the masses and splittings of the singly charmed baryons. As part of the calculation an analysis of the lower lying charmonium, $D$ and $D_s$ spectra was performed in order to assess discretisation errors. The gross spectra are reproduced, including the $D^*_{s0}$, $D_{s1}$ and $D_1$ mesons, while at this single lattice spacing hyperfine splittings come out $10-20$ MeV too low.

Strain and localization effects in InGaAs(N) quantum wells: Tuning the magnetic response

We investigated effects of localization and strain on the optical and magneto-optical properties of diluted nitrogen III–V quantum wells theoretically and experimentally. High-resolution x-ray diffraction, photoluminescence (PL), and magneto-PL measurements under high magnetic fields up to 15 T were performed at low temperatures. Bir-Pikus Hamiltonian formalism was used to study the influence of strain, confinement, and localization effects. The circularly polarized magneto-PL was interpreted considering localization aspects in the valence band ground state. An anomalous behavior of the electron-hole pair magnetic shift was observed at low magnetic fields, ascribed to the increase in the exciton reduced mass due to the negative effective mass of the valence band ground state.

Exciting flavored bound states

We study ground and radial excitations of flavor singlet and flavored pseudoscalar mesons within the framework of the rainbow-ladder truncation using an infrared massive and finite interaction in agreement with recent results for the gluon-dressing function from lattice QCD and Dyson-Schwinger equations. Whereas the ground-state masses and decay constants of the light mesons as well as charmonia are well described, we confirm previous observations that this truncation is inadequate to provide realistic predictions for the spectrum of excited and exotic states. Moreover, we find a complex conjugate pair of eigenvalues for the excited ${D}_{(s)}$ mesons, which indicates a non-Hermiticity of the interaction kernel in the case of heavy-light systems and the present truncation. Nevertheless, limiting ourselves to the leading contributions of the Bethe-Salpeter amplitudes, we find a reasonable description of the charmed ground states and their respective decay constants.

Ground-state masses and magnetic moments of heavy baryons

In this work, we study single, double and triple heavy-flavor baryons using the hypercentral approach in the framework of the non-relativistic quark model. Considering two different confining potentials and an improved form of the hyperfine interaction, we calculate the ground-state masses of heavy baryons and also the ground-state magnetic moments of single charm and beauty baryons with JP = 3/2+. The obtained results are in good agreement with experimental data and those of other works.

Charmonium spectral functions and transport properties of quark-gluon plasma

We study vacuum masses of charmonia and the charm-quark diffusion coefficient in the quark-gluon plasma based on the spectral representation for meson correlators. To calculate the correlators, we solve the quark gap equation and the inhomogeneous Bethe–Salpeter equation in the rainbow-ladder approximation. It is found that the ground-state masses of charmonia in the pseudoscalar, scalar, and vector channels can be well described. For 1.5Tc<T<3.0Tc, the value of the diffusion coefficient D is comparable with that obtained by lattice QCD and experiments: 3.4<2πTD<5.9. Relating the diffusion coefficient with the ratio of shear viscosity to entropy density η/s of the quark-gluon plasma, we obtain values in the range 0.09<η/s<0.16.

Spontaneous Fission Barriers Based on a Generalized Liquid Drop Model

The barrier against the spontaneous fission has been determined within the Generalized Liquid Drop Model (GLDM) including the mass and charge asymmetry, and the proximity energy. The shell correction of the spherical parent nucleus is calculated by using the Strutinsky method, and the empirical shape-dependent shell correction is employed during the deformation process. A quasi-molecular shape sequence has been defined to describe the whole process from one-body shape to two-body shape system, and a two-touching-ellipsoid is adopted when the superdeformed one-body system reaches the rupture point. On these bases the spontaneous fission barriers are systematically studied for nuclei from 230Th to 249Cm for different possible exiting channels with the different mass and charge asymmetries. The double, and triple bumps are found in the fission potential energy in this region, which roughly agree with the experimental results. It is found that at around Sn-like fragment the outer fission barriers are lower, while the partner of the Sn-like fragment is in the range near 108Ru where the ground-state mass is lowered by allowing axially symmetric shapes. The preferable fission channels are distinctly pronounced, which should be corresponding to the fragment mass distributions.

Mass spectrometry and decay spectroscopy of isomers across theZ=82shell closure

Recent results from a measurement campaign studying the isomerism in neutron-deficient Tl isotopes are presented. The measurements make use of a nuclear spectroscopy setup coupled to the high-resolution Penning-trap mass spectrometer ISOLTRAP at CERN's radioactive ion-beam facility ISOLDE. The mass values of ${}^{190,194}$Tl are improved and a mass-spin-state assignment is carried out. An additional mass measurement of the grandparent nuclide ${}^{198}$At allows the deduction of the spin-state ordering in ${}^{190}$Tl. As a result, the excitation energies of the isomers in both Tl isotopes are determined for the first time to ${E}_{\mathrm{ex}}{(}^{194}\text{Tl})=260(15)$ keV and ${E}_{\mathrm{ex}}{(}^{190}\text{Tl})=89(12)$ keV. Furthermore, this allows anchoring of the ground-state and isomer masses of ${}^{194}$Bi, ${}^{202}$Fr, and ${}^{206}$Ac, which are linked by two independent $\ensuremath{\alpha}$-decay chains.

TITAN: An ion trap facility for on-line mass measurement experiments

Precision determinations of ground state or even isomeric state masses reveal fingerprints of nuclear structure. In particular, at the limits of existence for very neutron-rich or -deficient isotopes, one can extract detailed information about nuclear structure from separation energies or binding energies. Mass measurements are important to uncover new phenomena, to test new theoretical predictions, or to refine model approaches. For example, the N = 28 shell has proven more stable than previously expected; however, the predicted new “magic” number at N = 34 in the K and Ca isotopes has yet to be confirmed experimentally. For these neutron-rich nuclei, the inclusion of three-body forces leads to significantly better predictions of the ground-state mass. Similarly, halo nuclei present an excellent application for ab-initio theory, where ground state properties, like masses and radii, test our understanding of nuclear structure. Precision mass determinations at TRIUMF are carried out with the TITAN (TRIUMF’s Ion Traps for Atomic and Nuclear science) facility. It is an ion-trap setup coupled to the on-line facility ISAC. TITAN has measured masses of isotopes as short-lived as 9 ms (almost an order of magnitude shorter-lived than any other Penning trap system), and it is the only one with charge breeding capabilities, which allow us to boost the precision by almost 2 orders of magnitude. We recently made use of this feature by measuring short-lived, proton-rich Rb-isotopes, up to 74Rb while reaching the 12 + charge state, which together with other improvements led to an increase in precision by a factor 36.