Jastrow-type calculations of one-nucleon removal reactions on open ss-dd shell nuclei

Single-particle overlap functions and spectroscopic factors are calculated on the basis of Jastrow-type one-body density matrices of open-shell nuclei constructed by using a factor cluster expansion. The calculations use the relationship between the overlap functions corresponding to bound states of the $(A-1)$-particle system and the one-body density matrix for the ground state of the $A$-particle system. In this work we extend our previous analyses of reactions on closed-shell nuclei by using the resulting overlap functions for the description of the cross sections of $(p,d)$ reactions on the open $s$-$d$ shell nuclei $^{24}$Mg, $^{28}$Si and $^{32}$S and of $^{32}$S$(e,e^{\prime}p)$ reaction. The relative role of both shell structure and short-range correlations incorporated in the correlation approach on the spectroscopic factors and the reaction cross sections is pointed out.Comment: 11 pages, 5 figures, to be published in Phys. Rev.

3P2^3P_2-3F2^3F_2 Pairing in Dense Neutron Matter: The Spectrum of Solutions

The $^3P_2$-$^3F_2$ pairing model is generally considered to provide an adequate description of the superfluid states of neutron matter at densities some 2-3 times that of saturated symmetrical nuclear matter. The problem of solving the system of BCS gap equations expressing the $^3P_2$-$^3F_2$ model is attacked with the aid of the separation approach. This method, developed originally for quantitative study of S-wave pairing in the presence of strong short-range repulsions, serves effectively to reduce the coupled, singular, nonlinear BCS integral equations to a set of coupled algebraic equations. For the first time, sufficient precision becomes accessible to resolve small energy splittings between the different pairing states. Adopting a perturbative strategy, we are able to identify and characterize the full repertoire of real solutions of the $^3P_2$-$^3F_2$ pairing model, in the limiting regime of small tensor-coupling strength. The P-F channel coupling is seen to lift the striking parametric degeneracies revealed by a earlier separation treatment of the pure, uncoupled $^3P_2$ pairing problem. Remarkably, incisive and robust results are obtained solely on the basis of analytic arguments. Unlike the traditional Ginzburg-Landau approach, the analysis is not restricted to the immediate vicinity of the critical temperature, but is equally reliable at zero temperature. Interesting connections and contrasts are drawn between triplet pairing in dense neutron matter and triplet pairing in liquid $^3$He.Comment: 23 pages, 1 figur

Do children get dry socket?—The incidence and pattern of presentation of alveolar osteitis in children and adolescents following dental extractions

Background Alveolar osteitis (AO) is widely reported as the most common post-operative complication following surgical and non-surgical exodontia. Despite being one of the most studied complications in dentistry, there is no established consensus on its aetiology, alongside a relative paucity of studies looking exclusively into AO incidence in children and adolescents. Objectives To determine the incidence, risk factors and pattern of presentation of AO in children and adolescents following exodontia, as well as identifying concepts and theories to provide a basis regarding why such a common post-operative complication reportedly manifests so rarely in the paediatric population. Methods This cross-sectional analysis forms part of a prospective service evaluation of the exodontia service provided by Newcastle Dental Hospital. All patients aged 5–16 who underwent dental extractions of deciduous and/or permanent teeth under general anaesthetic (GA) between 15 June 2020 and the 15 July 2020 were telephoned 1 week following their procedure to determine if any had developed post-operative complications. Data were cleaned manually and analysed using descriptive statistics, exploratory analysis with chi-squared tests and multivariable analyses. A scoping review was performed using the PubMed, OVID Medline and Scopus databases. Results Four of 150 patients (2.8%) developed AO and reported extreme pain which began 2–3 days after removal, lasted 2 days after onset, and were all associated with the non-surgical removal of lower first permanent molar teeth. All patients who developed AO were female and aged between 9 and 10 years old. Mandibular sockets were significantly associated with development of AO (p = 0.026). Conclusions Despite the belief that AO rarely manifests in children, the incidence of paediatric AO in this study is in line with that of AO found in the adult literature. The literature is inconsistent and conflicting regarding current understanding of AO. As far as possible, an atraumatic approach to exodontia should be adopted. We have proposed four underlying concepts which may benefit from future research given the paucity of research exclusively into dry socket in children and adolescents

PHYSICS MEASUREMENTS ON THE SNAP EXPERIMENTAL REACTOR (SER)

Prior to operation of the SER at temperature and power and with NaK coolant present, a series of measurements were performed in the neighborhood of room temperature and at powers of 1 watt or less. These measurements were designed to establish the characteristics of the system under controlled conditions and to determine safe operating procedures. Measurements were made to determine critical mass in various reflector configurations, control drum and safety element worth, flux mappings in the reactor and importance mappings external to the reactor, reactivity coefficients of various materials, and kinetic parameters. The most important conclusion drawn is that the system as designed hns the necessary reactivity and control for its anticipated operation. Full feasibility determinations must necessarily wait upon the outcome of experiments at power and temperature. (auth

Entropy paradox in strongly correlated Fermi systems

A system of interacting, identical fermions described by standard Landau Fermi-liquid (FL) theory can experience a rearrangement of its Fermi surface if the correlations grow sufficiently strong, as occurs at a quantum critical point where the effective mass diverges. As yet, this phenomenon defies full understanding, but salient aspects of the non-Fermi-liquid (NFL) behavior observed beyond the quantum critical point are still accessible within the general framework of the Landau quasiparticle picture. Self-consistent solutions of the coupled Landau equations for the quasiparticle momentum distribution $n(p)$ and quasiparticle energy spectrum $\epsilon(p)$ are shown to exist in two distinct classes, depending on coupling strength and on whether the quasiparticle interaction is regular or singular at zero momentum transfer. One class of solutions maintains the idempotency condition $n^2(p)=n(p)$ of standard FL theory at zero temperature $T$ while adding pockets to the Fermi surface. The other solutions are characterized by a swelling of the Fermi surface and a flattening of the spectrum $\epsilon(p)$ over a range of momenta in which the quasiparticle occupancies lie between 0 and 1 even at T=0. The latter, non-idempotent solution is revealed by analysis of a Poincar\'e mapping associated with the fundamental Landau equation connecting $n(p)$ and $\epsilon(p)$ and validated by solution of a variational condition that yields the symmetry-preserving ground state. Paradoxically, this extraordinary solution carries the burden of a large temperature-dependent excess entropy down to very low temperatures, threatening violation of the Nernst Theorem. It is argued that certain low-temperature phase transitions offer effective mechanisms for shedding the entropy excess. Available measurements in heavy-fermion compounds provide concrete support for such a scenario.Comment: 34 pages, 6 figure

Systematic study of the effect of short range correlations on the form factors and densities of s-p and s-d shell nuclei

Analytical expressions of the one- and two-body terms in the cluster expansion of the charge form factors and densities of the s-p and s-d shell nuclei with N=Z are derived. They depend on the harmonic oscillator parameter b and the parameter $\beta$ which originates from the Jastrow correlation function. These expressions are used for the systematic study of the effect of short range correlations on the form factors and densities and of the mass dependence of the parameters b and $\beta$. These parameters have been determined by fit to the experimental charge form factors. The inclusion of the correlations reproduces the experimental charge form factors at the high momentum transfers ($q\geq 2 1/fm$). It is found that while the parameter $\beta$ is almost constant for the closed shell nuclei, $^4$He, $^{16}$O and $^{40}$Ca, its values are larger (less correlated systems) for the open shell nuclei, indicating a shell effect in the closed shell nuclei.Comment: Latex, 21 pages, 6 figures, 1 tabl

Effects of Short Range Correlations on Ca Isotopes

The effect of Short Range Correlations (SRC) on Ca isotopes is studied using a simple phenomenological model. Theoretical expressions for the charge (proton) form factors, densities and moments of Ca nuclei are derived. The role of SRC in reproducing the empirical data for the charge density differences is examined. Their influence on the depletion of the nuclear Fermi surface is studied and the fractional occupation probabilities of the shell model orbits of Ca nuclei are calculated. The variation of SRC as function of the mass number is also discussed.Comment: 11 pages (RevTex), 6 Postscript figures available upon request at [email protected] Physical Review C in prin

Quasi-long-range order in the random anisotropy Heisenberg model: functional renormalization group in 4-\epsilon dimensions

The large distance behaviors of the random field and random anisotropy O(N) models are studied with the functional renormalization group in 4-\epsilon dimensions. The random anisotropy Heisenberg (N=3) model is found to have a phase with the infinite correlation radius at low temperatures and weak disorder. The correlation function of the magnetization obeys a power law < m(x) m(y) >\sim |x-y|^{-0.62\epsilon}. The magnetic susceptibility diverges at low fields as \chi \sim H^{-1+0.15\epsilon}. In the random field O(N) model the correlation radius is found to be finite at the arbitrarily weak disorder for any N>3. The random field case is studied with a new simple method, based on a rigorous inequality. This approach allows one to avoid the integration of the functional renormalization group equations.Comment: 12 pages, RevTeX; a minor change in the list of reference

Adaptation of the Landau-Migdal Quasiparticle Pattern to Strongly Correlated Fermi Systems

A quasiparticle pattern advanced in Landau's first article on Fermi liquid theory is adapted to elucidate the properties of a class of strongly correlated Fermi systems characterized by a Lifshitz phase diagram featuring a quantum critical point (QCP) where the density of states diverges. The necessary condition for stability of the Landau Fermi Liquid state is shown to break down in such systems, triggering a cascade of topological phase transitions that lead, without symmetry violation, to states with multi-connected Fermi surfaces. The end point of this evolution is found to be an exceptional state whose spectrum of single-particle excitations exhibits a completely flat portion at zero temperature. Analysis of the evolution of the temperature dependence of the single-particle spectrum yields results that provide a natural explanation of classical behavior of this class of Fermi systems in the QCP region.Comment: 26 pages, 14 figures. Dedicated to 100th anniversary of A.B.Migdal birthda