The recent observation of a hadronic resonance d⁎ in the proton–neutron system with isospin I=0 and spin-parity JP=3+ raises the possibility of producing other novel six-quark dibaryon configurations ...allowed by QCD. A dramatic example of an exotic six-quark color-singlet system is the charge Q=+4, isospin I=3, Iz=+3|uuuuuu〉 state which couples strongly to Δ+++Δ++. The width and decay properties of such six-quark resonances could be regarded as manifestations of “hidden-color” six-quark configurations, a first-principle prediction of QCD – SU(3)-color gauge theory for the deuteron distribution amplitude. Other implications and possible future experiments are discussed.
Despite many decades of study the physical origin of 'dark matter' (DM) in the Universe remains elusive. In this letter we calculate the properties of a completely new DM candidate-Bose-Einstein ...condensates formed from a recently discovered bosonic particle in the light-quark sector, the d * ( 2380 ) hexaquark. In this first study, we show stable d ∗ ( 2380 ) Bose-Einstein condensates could form in the primordial early universe, with a production rate sufficiently large that they are a plausible new candidate for DM. Some possible astronomical signatures of such DM are also presented.
Positron Emission Tomography (PET) is a widely-used imaging modality for medical research and clinical diagnosis. Imaging of the radiotracer is obtained from the detected hit positions of the two ...positron annihilation photons in a detector array. The image is degraded by backgrounds from random coincidences and in-patient scatter events which require correction. In addition to the geometric information, the two annihilation photons are predicted to be produced in a quantum-entangled state, resulting in enhanced correlations between their subsequent interaction processes. To explore this, the predicted entanglement in linear polarisation for the two photons was incorporated into a simulation and tested by comparison with experimental data from a cadmium zinc telluride (CZT) PET demonstrator apparatus. Adapted apparati also enabled correlation measurements where one of the photons had undergone a prior scatter process. We show that the entangled simulation describes the measured correlations and, through simulation of a larger preclinical PET scanner, illustrate a simple method to quantify and remove the unwanted backgrounds in PET using the quantum entanglement information alone.
Elucidating the appropriate microscopic degrees of freedom within neutron stars remains an open question which impacts nuclear physics, particle physics and astrophysics. The recent discovery of the ...first non-trivial dibaryon, the d⁎(2380), provides a new candidate for an exotic degree of freedom in the nuclear equation of state at high matter densities. In this paper a first calculation of the role of the d⁎(2380) in neutron stars is performed based on a relativistic mean field description of the nucleonic degrees of freedom supplemented by a free boson gas of d⁎(2380). The calculations indicate that the d⁎(2380) would appear at densities around three times normal nuclear matter saturation density and comprise around 20% of the matter in the centre of heavy stars with higher fractions possible in the higher densities of merger processes. The d⁎(2380) would also reduce the maximum star mass by around 15% and have significant influence on the fractional proton/neutron composition. New possibilities for neutron star cooling mechanisms arising from the d⁎(2380) are also predicted.
We present the extension of a previous study where, assuming a simple free bosonic gas supplemented with a relativistic mean-field model to describe the pure nucleonic part of the equation of state, ...we studied the consequences that the first non-trivial hexaquark
d
*
(2380) could have on the properties of neutron stars. Compared to that exploratory work, we employ a standard non-linear Walecka model including additional terms that describe the interaction of the
d
*
(2380) di-baryon with the other particles of the system through the exchange of
σ
- and
ω
-meson fields. Our results show that the presence of the
d
*
(2380) leads to maximum masses compatible with recent observations of ∼2
M
⊙
millisecond pulsars if the interaction of the
d
*
(2380) is slightly repulsive or the
d
*
(2380) does not interact at all. An attractive interaction makes the equation of state too soft to be able to support a 2
M
⊙
neutron star whereas an extremely repulsive one induces the collapse of the neutron star into a black hole as soon as the
d
*
(2380) appears.
Recently a two-step process has been proposed for the double-pionic fusion to deuterium pn(I=0)→dπ+π−. Its calculation is solely based on total cross section data for the two sequential single-pion ...production steps pn(I=0)→ppπ− followed by pp→dπ+. Though this sequential process was aimed to explain the dibaryon resonance d⁎(2380) peak in double-pionic fusion, we demonstrate that this is not the case. It rather fits to a possible broad bump at 2.31 GeV in the energy dependence of the pn→dπ0π0 reaction, which was recently interpreted as a consequence of dibaryonic excitations in isoscalar single-pion production.
PDF
