We consider the proton and neutron quasiparticle orbits around the closed-shell (56)Ni and (48)Ca isotopes. It is found that large model spaces (beyond the capability of shell model applications) are ...necessary for predicting the quenching of spectroscopic factors. The particle-vibration coupling is identified as the principal mechanism. Additional correlations--due to configuration with several particle-hole excitations--are estimated using shell model calculations and generate an extra reduction which is < or approximately equal to 4% for most quasiparticle states. The theoretical calculations nicely agree with (e, e'p) and inverse kinematics knockout experiments. These results open a new path for a microscopic understanding of the shell model.
We extend the formalism of self-consistent Green's function theory to include three-body interactions and apply it to isotopic chains around oxygen for the first time. The third-order algebraic ...diagrammatic construction equations for two-body Hamiltonians can be exploited upon defining system-dependent one- and two-body interactions coming from the three-body force, and, correspondingly, dropping interaction-reducible diagrams. The Koltun sum rule for the total binding energy acquires a correction due to the added three-body interaction. This formalism is then applied to study chiral two- and three-nucleon forces evolved to low momentum cutoffs. The binding energies of nitrogen, oxygen, and fluorine isotopes are reproduced with good accuracy and demonstrate the predictive power of this approach. Leading order three-nucleon forces consistently bring results close to the experiment for all neutron rich isotopes considered and reproduce the correct driplines for oxygen and nitrogen. The formalism introduced also allows us to calculate form factors for nucleon transfer on doubly magic systems.
The fate and observable properties of gamma-ray burst jets crucially depend on their interaction with the progenitor material that surrounds the central engine. We present a semi-analytical model of ...this interaction (which builds upon several previous analytical and numerical works) aimed at predicting the angular distribution of jet and cocoon energy and Lorentz factor after breakout given the properties of the ambient material and of the jet at launch. Using this model, we constructed synthetic populations of structured jets, assuming either a collapsar (for long gamma-ray bursts – LGRBs) or a binary neutron star merger (for short gamma-ray bursts – SGRBs) as progenitor. We assumed all progenitors to be identical, and we allowed little variability in the jet properties at launch: our populations therefore feature a quasi-universal structure. These populations are able to reproduce the main features of the observed LGRB and SGRB luminosity functions, although several uncertainties and caveats have yet to be addressed. We make our simulated populations publicly available.
We derive ab initio optical potentials from self-consistent Green's function theory and compute the elastic scattering of neutrons off oxygen and calcium isotopes. The comparison with scattering data ...is satisfactory at low scattering energies. The method is benchmarked against the no-core shell model with continuum calculations, showing that virtual excitations of the target are crucial to predict proper fragmentation and absorption at higher energies. This is a significant step toward deriving optical potentials for medium mass nuclei and complex many-body systems in general.
We present the first ab initio calculations for open-shell nuclei past the tin isotopic line, focusing on Xe isotopes as well as doubly magic Sn isotopes. We show that, even for moderately hard ...interactions, it is possible to obtain meaningful predictions and that the NNLOsat chiral interaction predicts radii and charge density distributions close to the experiment. We then make a new prediction for Sn100. This paves the way for ab initio studies of exotic charge density distributions at the limit of the present ab initio mass domain, where experimental data is becoming available. The present study closes the gap between the largest isotopes reachable by ab initio methods and the smallest exotic nuclei accessible to electron scattering experiments.
Detections of gravitational waves (GWs) may soon uncover the signal from the coalescence of a black hole–neutron star (BHNS) binary, which is expected to be accompanied by an electromagnetic (EM) ...signal. In this paper, we present a composite semi-analytical model to predict the properties of the expected EM counterpart from BHNS mergers, focusing on the kilonova emission and on the gamma-ray burst afterglow. Four main parameters rule the properties of the EM emission: the NS mass
M
NS
, its tidal deformability
Λ
NS
, the BH mass and spin. Only for certain combinations of these parameters an EM counterpart is produced. Here we explore the parameter space, and construct light curves, analyzing the dependence of the EM emission on the NS mass and tidal deformability. Exploring the NS parameter space limiting to
M
NS
-
Λ
NS
pairs described by a physically motivated equations of state (EoS), we find that the brightest EM counterparts are produced in binaries with low-mass NSs (fixing the BH properties and the EoS). Using constraints on the NS EoS from GW170817, our modeling shows that the emission falls in a narrow range of absolute magnitudes. Within the range of explored parameters, light curves and peak times are not dissimilar to those from NSNS mergers, except in the B band. The lack of an hyper/supra-massive NS in BHNS coalescences causes a dimming of the blue kilonova emission in the absence of the neutrino interaction with the ejecta.
In the new era of gravitational wave (GW) and multi-messenger astrophysics, the detection of a GW signal from the coalescence of a black hole – neutron star (BHNS) binary remains a highly anticipated ...discovery. This system is expected to be within reach of the second generation of ground-based detectors. In this context, we develop a series of versatile semi-analytical models to predict the properties of all the electromagnetic (EM) counterparts of BHNS mergers. We include the nuclear-decay-powered kilonova emission, its radio remnant, the prompt emission from the jet, and the related afterglow. The properties of these counterparts depend upon those of the outflows that result from the partial disruption of the NS during the merger and from the accretion disc around the remnant, which are necessary ingredients for transient EM emission to accompany the GW signal. We therefore define ways to relate the properties of these outflows to those of the progenitor binary, establishing a link between the binary parameters and the counterpart properties. From the resulting model, we anticipate the variety of light curves that can emerge after a BHNS coalescence from the radio up to gamma-rays. These light curves feature universal traits that are the imprint of the dynamics of the emitting outflows, but at the same time, they show a clear dependence on the BH mass and spin, but with a high degree of degeneracy. The latter can be deduced by a joint GW – EM analysis. In this paper, we perform a proof-of-concept multi-messenger parameter estimation of a BHNS merger with an associated kilonova to determine how the information from the EM counterpart can complement that from the GW signal. Our results indicate that the observation and modelling of the kilonova can help to break the degeneracies in the GW parameter space, leading to better constraints on the BH spin, for example.
We present a systematic study of both nuclear radii and binding energies in (even) oxygen isotopes from the valley of stability to the neutron drip line. Both charge and matter radii are compared to ...state-of-the-art ab initio calculations along with binding energy systematics. Experimental matter radii are obtained through a complete evaluation of the available elastic proton scattering data of oxygen isotopes. We show that, in spite of a good reproduction of binding energies, ab initio calculations with conventional nuclear interactions derived within chiral effective field theory fail to provide a realistic description of charge and matter radii. A novel version of two- and three-nucleon forces leads to considerable improvement of the simultaneous description of the three observables for stable isotopes but shows deficiencies for the most neutron-rich systems. Thus, crucial challenges related to the development of nuclear interactions remain.
To determine if mexiletine is safe and effective in reducing myotonia in myotonic dystrophy type 1 (DM1).
Myotonia is an early, prominent symptom in DM1 and contributes to decreased dexterity, gait ...instability, difficulty with speech/swallowing, and muscle pain. A few preliminary trials have suggested that the antiarrhythmic drug mexiletine is useful, symptomatic treatment for nondystrophic myotonic disorders and DM1.
We performed 2 randomized, double-blind, placebo-controlled crossover trials, each involving 20 ambulatory DM1 participants with grip or percussion myotonia on examination. The initial trial compared 150 mg of mexiletine 3 times daily to placebo, and the second trial compared 200 mg of mexiletine 3 times daily to placebo. Treatment periods were 7 weeks in duration separated by a 4- to 8-week washout period. The primary measure of myotonia was time for isometric grip force to relax from 90% to 5% of peak force after a 3-second maximum grip contraction. EKG measurements and adverse events were monitored in both trials.
There was a significant reduction in grip relaxation time with both 150 and 200 mg dosages of mexiletine. Treatment with mexiletine at either dosage was not associated with any serious adverse events, or with prolongation of the PR or QTc intervals or of QRS duration. Mild adverse events were observed with both placebo and mexiletine treatment.
Mexiletine at dosages of 150 and 200 mg 3 times daily is effective, safe, and well-tolerated over 7 weeks as an antimyotonia treatment in DM1.
This study provides Class I evidence that mexiletine at dosages of 150 and 200 mg 3 times daily over 7 weeks is well-tolerated and effective in reducing handgrip relaxation time in DM1.
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