Mass formula

About: Mass formula is a research topic. Over the lifetime, 1248 publications have been published within this topic receiving 22043 citations.

Non-Abelian Cornucopions

Abstract: An infinite family of cornucopions is found within the $SU(2)\times U(1)$ sector of the 4--d heterotic string low-energy theory, the extremal $U(1)$ magnetic dilatonic black hole being the lowest energy state. Non-abelian cornucopions are interpreted as sphalerons associated with potential barriers separating topologically distinct Yang-Mills vacua on the $U(1)$ cornucopion background. A mass formula for non-abelian dilatonic black holes is derived, and the free energy is calculated through the Euclidean action.

Even Wave Harmonic Oscillator Theory of Baryonic States: A New Classification

Abstract: An even-wave harmonic oscillator (h.o.) model for the quark-quark interaction proposed recently for the baryon spectrum is described with a detailed mathematical formulation. The mechanism, which formally admits of a relativistic extension of the Feynman-Kislinger-Ravndal type, leaves unchanged the usual h.o. predictions for 56 states (symmetric) for all L values even and odd, but totally keeps out the 20 states (antisymmetric). It changes the structure of the 70 states considerably, while retaining the principal feature of linear rise of (mass) 2 with J through the interplay of two reduced slopes of magnitudes ½ α and ½ √ 3α , compared to a for the 56 spectrum. The new features of the 70 states are (i) a dual spectrum leading to considerable mass splitting compared to the usual h.o. model without SU(6)-breaking effects, (ii) prediction of a unique (70, 0 + ) supermultiplet lower than the (70, 1 - ), and (iii) the prediction of low radial excitations because of the reduced slopes. The immediate experimental successes are (i) an understanding of P 11 (1470) together with possible Δ, Σ, Λ counterparts, (ii) two distinct mass groupings manifest in (70, 1 - ) states, and (iii) plausible explanation of P 11 '(1750) as a radial excitation of P 11 (1470). The mass splittings of Δ, Σ, Λ from their N counterparts, compared for 56 and 70 states, conform extremely well to the ratio of the average slope δ=1/4α(1+√3)≈ 0.68 a for 70 states to that (a) for the 56, thus facilitating the prediction of Δ, Σ, Λ positions from those of N states for different quantum numbers. Extra predictions of states are discussed in terms of an extended classification scheme given by an ordered set of four quantum numbers (n x l x n y l y ) defined in the text.

New equations of state based on the liquid drop model of heavy nuclei and quantum approach to light nuclei for core-collapse supernova simulations

Abstract: We construct new equations of state for baryons at sub-nuclear densities for the use in core-collapse simulations of massive stars. The abundance of various nuclei is obtained together with thermodynamic quantities. A model free energy is constructed, based on the relativistic mean field theory for nucleons and the mass formula for nuclei with the proton number up to ~ 1000. The formulation is an extension of the previous model, in which we adopted the liquid drop model to all nuclei under the nuclear statistical equilibrium. We reformulate the new liquid drop model so that the temperature dependences of bulk energies could be taken into account. Furthermore, we extend the region in the nuclear chart, in which shell affects are included, by using theoretical mass data in addition to experimental ones. We also adopt a quantum theoretical mass evaluation of light nuclei, which incorporates the Pauli- and self-energy shifts that are not included in the ordinary liquid drop model. The pasta phases for heavy nuclei are taken into account in the same way as in the previous model. We find that the abundances of heavy nuclei are modified by the shell effects of nuclei and temperature dependence of bulk energies. These changes may have an important effect on the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores. The abundances of light nuclei are also modified by the new mass evaluation, which may affect the heating and cooling rates of supernova cores and shocked envelopes.

The Limiting Mass of a Neutron Star

Abstract: ASSUMING that pulsars are spinning, contracted stellar objects of enormous mass, we can divide the interior of a pulsar into three distinct density regions. Region 1 has a density below 5 × 1011 g cm−3, region 2 has a density from 5 × 1011 to 1015 g cm−3 and region 3 has a density > 1015 g cm−3. In region 1, the pressure is generated by an electron gas obeying the laws of atomic physics and the semi-empirical nuclear mass formula plays an important part in the equation of state. The unsolved problems will not require new methods, but only better accuracy.