abstract

The cross sections of \(e^+e^- \to \omega \chi _{cJ(J=0,1,2)}\) have been measured by BESIII. We try to search for vector charmonium(-like) states \(Y(4220)\), \(Y(4360)\), \(\psi (4415)\) and \(Y(4660)\) in the \(e^+e^- \to \omega \chi _{cJ(J=0,1,2)}\) line shapes. The \(\omega \chi _{c0}\) mainly comes from \(Y(4220)\), \(\omega \chi _{c1}\) mainly comes from \(Y(4660)\) and \(\omega \chi _{c2}\) mainly comes from \(\psi (4415)\), maybe partly comes from \(Y(4360)\) or \(Y(4660)\). For the charmonium(-like) states that are not significant in the \(e^+e^- \to \omega \chi _{cJ(J=0,1,2)}\) line shape, we also give the 90% confidence level upper limits on the electron partial width multiplied by branching fraction. These results are helpful to study the nature of charmonium(-like) states in this energy region.

abstract

A model explaining the shape of the spectral line in the \({}^{12}\mathrm {C}(p,p'\gamma _{4.44}){}^{12}\)C nuclear reaction has been applied to data collected during an experiment conducted at the Heidelberg Ion-Beam Therapy Center. Spectra were recorded for a graphite target setup, initial proton beam energies of 70.54 MeV and 88.97 MeV, which were later degraded before reaching the main target, and detection angles ranging from \(90^\circ \) to \(150^\circ \). The model calculations reproduced experimental data and determined the angular distribution of the nuclear reaction. This article presents the details of the model along with a description of the subsequent analysis steps and results.

abstract

Triple-shape coexistence and superdeformation in Pb isotopes with neutron numbers \(N=96\)–138 is studied. The constrained calculations are performed within the Relativistic Hartree–Bogoliubov (RHB) model using DD-ME2, DD-PC1, and NL3* force parameters, and pairing interaction separable in momentum space. Triple-shape coexistence (spherical, prolate and oblate) manifests themselves in a clear manner in \(^{184-190}\)Pb nuclei with axial RHB calculations. Triaxial RHB calculations further confirm the findings. Superdeformed minimum is observed for \(^{188-220}\)Pb isotopes, and the corresponding excitation energy, deformation and depth of well are comparable within different force parameters used. The behaviour with neutron number of the superdeformed excitation energy, two-neutron separation energy in the ground state and superdeformed minimum, and its differential are fairly reproducing the trend of the available experimental data. The present numerical results are compared with Macro–microscopic Finite Range Droplet Model (FRDM) and Hartree–Fock–Bogoliubov (HFB) model based on the interaction Gogny-D1S force. Overall, a fairly satisfactory agreement is found within the different force parameters and the calculated and experimental results.

abstract

We consider a model of an unstable state defined by the truncated Breit–Wigner energy density distribution function. An analytical form of the survival amplitude \(a(t)\) of the state considered is found. Our attention is focused on the late time properties of \(a(t)\) and on effects generated by the non-exponential behavior of this amplitude in the late time region: In 1957, Khalfin proved that this amplitude tends to zero as \(t\) goes to the infinity more slowly than any exponential function of \(t\). This effect can be described using a time-dependent decay rate \(\gamma (t)\), and then the Khalfin result means that this \(\gamma (t)\) is not a constant but at late times, it tends to zero as \(t\) goes to the infinity. It appears that the energy \(E(t)\) of the unstable state behaves similarly: It tends to the minimal energy \(E_{\rm min}\) of the system as \(t \to \infty \). Within the model considered, we find two first leading time-dependent elements of late time asymptotic expansions of \(E(t)\) and \(\gamma (t)\). We discuss also possible implications of such a late time asymptotic properties of \(E(t)\) and \(\gamma (t)\) and cases where these properties may manifest themselves.

abstract

The two-dimensional BTW model of self-organised criticality (SOC) with critical height, \(z_{\rm c}=8\), is studied by computer simulation in the following two different cases. When the value of height variable of a particular site reaches the critical value, \(z_{\rm c}=8\), the value of height variable of that site is reduced by eight units: (i) by distributing eight particles among the four nearest neighbouring sites and four next nearest neighbouring sites, each receiving one particle at a time; (ii) by distributing eight particles among the four nearest neighbouring sites, each receiving two particles at a time. It is observed that in the SOC state, the average (spatial) value of height variable, \(\bar z\), in the BTW model with next nearest neighbour is less than that in the BTW model with only nearest neighbour. But in the SOC state, the distributions of avalanche sizes and durations are identical in both the cases. The distribution of the size of clusters for different values of height variable have been studied in both the cases of BTW model.

abstract

A Quantum Field Theoretic analysis has led to the claim that liquid water supports coherent domains of almost millimeter size [E. Del Giudice, G. Preparata, G. Vitiello, Phys. Rev. Lett. 61, 1085 (1988)]. Such domains would be described by one quantum mechanical state function. Further analysis results in new characteristic frequencies and in the claim that a long-range (\(\gt 100 \ \mu \)m) structure emerges around a molecular size dipole. The quantum-physics-based claim that liquid water supports structures of over 100 micrometer in size at room temperature is irreconcilable with a well-known consensus of condensed matter physics: Brownian collisions make wave functions collapse and hot, wet environments do not allow for quantum entanglements to survive. Simulations, theory, and experiment agree on how a hydration shell of a few layers of directed water dipoles forms around an ion or a polar molecule. Such a shell extends to less than a nanometer. We reexamine the assumptions and theory behind the coherent domain dynamics in water. It appears likely that large, long-lasting coherent domains do not emerge in liquid water.