Table of contents for issue 1, volume 42, Journal of Physics G: Nuclear and Particle Physics

We discuss the electron antineutrino fluence derived from the events detected by Kamiokande-II, IMB and Baksan on 23 February 1987. The data are analysed adopting a new simple and accurate formula for the signal, improving on the previous modeling of the detectors response, considering the possibility of background events. We perform several alternative analyses to quantify the relevance of various descriptions, approximations and biases. In particular, we study the effect of: omitting Baksan data or neglecting the background, using simplified formulae for the signal, modifying the fluence to account for oscillations and pinching, including the measured times and angles of the events, using other descriptions of detector response, etc. We show that most of these effects are small or negligible and argue, by comparing the allowed regions for astrophysical parameters, that the results are stable. We comment on the accordance with theoretical results and on open questions.

We calculate the isovector axial vector form factors of the octet–decuplet hyperon transitions within the framework of the light-cone QCD sum rules to leading in QCD and including higher-twist corrections. In particular, we motivate the most recent version of the Σ and Λ baryons distribution amplitudes, which are examined up to twist-6 based on conformal symmetry of the massless QCD Lagrangian.

Considering the situation that a single chiral particle, η is initially emitted, we study the hidden-charm di-eta decays of the charmoniumlike state and the predicted charmonium , i.e., through the inetermediates and/or , and answer the important question of whether there exist isoscalar charmoniumlike structures in the and/or channels. Our results predict that there will be enhancement structures near , and thresholds for and near , and thresholds for in the distributions of , respectively. These peaks are accessible in future experiments, especially BESIII, Belle, BaBar, and the forthcoming BelleII.

The pion distribution amplitude (DA) can be related to the fundamental QCD Greenʼs functions as a function of the quark self-energy and the quark–pion vertex, which in turn are associated with the pion wave function through the Bethe–Salpeter equation. Considering the extreme hard asymptotic behavior in momentum space allowed for a pseudoscalar wave function, which is limited by its normalization condition, we compute the pion DA and its second moment. From the resulting amplitude, representing the field theoretical upper limit on the DA behavior, we calculate the photon–pion transition form factor . The resulting upper limit on the pion transition form factor is compared with existing data published by CLEO, BaBar and Belle Collaborations.

In the framework of the linear σ-model (LSM) with three quark flavors, the chiral phase diagram at finite temperature and density is investigated. For temperatures higher than the critical temperature (), we added to the LSM the gluonic sector from the quasi-particle model (QPM), which assumes that the interacting gluons in the strongly interacting matter, the quark–gluon plasma (QGP), are phenomenologically the same as non-interacting massive quasi-particles. The dependence of the chiral condensates of strange and non-strange quarks on the temperature and chemical potential is analyzed. Then, we calculate the thermodynamics in the new approach (using a combination of the LSM and the QPM). Confronting the results with those from recent lattice quantum chromodynamics simulations reveals an excellent agreement for almost all thermodynamic quantities. The dependences of the first-order and second-order moments of the particle multiplicity on the chemical potential at fixed temperature are studied. These investigations are implemented through characterizing the large fluctuations accompanying the chiral phase transition. The results for the first-order and second-order moments are compared with those from the (3) Polyakov linear σ-model (PLSM). Also, the resulting phase diagrams deduced in the PLSM and the LSM+QPM are compared with each other.

We describe the implementation of top production and decay processes in the parton-level Monte Carlo program MCFM. By treating the top quark as being on-shell, we can factorize the amplitudes for top-pair production, s-channel single-top production, and t-channel single-top production into the product of an amplitude for production and an amplitude for decay. In this way we can retain all spin correlations. Both the production and the decay amplitudes are calculated consistently at next-to-leading order in . The full dependence on the b-quark mass is also kept. Phenomenological results are presented for various kinematic distributions at the LHC and for the top quark forward–backward asymmetry at the Tevatron.

A folding potential for elastic ²⁰Ne + ²⁰Ne scattering is constructed based on the model of ²⁰Ne nucleus. The elastic scattering angular distributions at energies of 62.1–74.5 MeV can be reasonably described. Linear expressions of energy-dependent of the renormalization factor N and the central imaginary depth W₀ are obtained from the analyzes of the elastic angular distributions. The excitation function for the elastic ²⁰Ne + ²⁰Ne scattering at in the energy region of E_c.m. 30–38 MeV can be well reproduced by the linear energy-dependent potential.

Projectile fragmentation cross sections are calculated for reactions of and on C, Al, Cu, and Pb targets at 400 A MeV by using the improved quantum molecular dynamics model, together with the statistical model code GEMINI. The total cross sections increase with increasing target mass, which is in good agreement with the experimental results and other theoretical predictions. The isotopic distributions and isospin distributions suggest that the odd–even effect is dependent on the projectile nuclei. For a projectile with , the partial cross sections appear an obvious odd–even effect, and the isotopic distributions show that the maximal cross sections for the even-Z isotope are larger than that for the neighboring odd-Z isotope. However, the fragmentation cross sections and the isotopic distributions for the projectile have not shown these characteristics. The isospin distributions show that the odd–even effect of fragments from the projectile is stronger than that from the projectile.

We investigate the cluster emission of Ne isotopes from the nuclei and . Experiments are unable to distinguish between the isotopes and , but by establishing a method of determining the cluster, with associated preformation probability, and using a binary cluster formalism, we deduce that the most likely emitted cluster is .

Through the Monte Carlo simulation of the three-dimensional, three-state Potts model, which is a paradigm of finite-temperature pure gauge quantum chromodynamics, we study the fluctuations of generalized susceptibilities near the temperatures of external fields of first- and second-order phase transitions and crossover. Similar peak-like fluctuation appears in the second-order susceptibility at three given external fields. Oscillation-like fluctuation appears in the third- to sixth-order susceptibilities. We find that these non-monotonic fluctuations are not only associated with the second-order phase transition, but also the first-order one and crossover in a system of finite size. We further present the finite-size scaling analysis of the second- and fourth-order susceptibilities. The exponent of the scaling characterizes the order of the transitions, or the crossover.

The evaporation residue of barium isotopes is investigated in a microscopic study using relativistic mean field theory. The investigation includes the isotopes of barium from the valley of stability to the exotic proton-rich region. The ground as well as neck configurations for these nuclei are generated from their total nucleonic density distributions of the corresponding state. We have estimated the constituents (number of nucleons) in the elongated neck region of the fission state. We found the α-particle as the constituent of the neck of Ba-isotopes, referred to as the evaporated residue in heavy-ion reaction studies. A strong correlation between the neutron and proton is observed throughout the isotopic chain.

We report on the results of the calculations of the low energy excitation patterns for three Zirconium isotopes, viz ⁸⁰Zr₄₀, ⁹⁶Zr₅₆ and ¹¹⁰Zr₇₀, reported by other authors to be doubly-magic tetrahedral nuclei (with tetrahedral magic numbers Z = 40 and N = 40, 56 and 70). We employ the realistic Gogny effective interactions using three variants of their parametrization and the particle-number, parity and the angular-momentum projection techniques. We confirm quantitatively that the resulting spectra directly follow the pattern expected from the group theory considerations for the tetrahedral symmetric quantum objects. We also find out that, for all the nuclei studied, the correlation energy obtained after the angular momentum projection is very large for the tetrahedral deformation as well as other octupole deformations. The lowering of the energies of the resulting configurations is considerable, i.e. by about 10 MeV or even more, once again confirming the significance of the angular-momentum projections techniques in the mean-field nuclear structure calculations.

The elastic differential cross section is calculated at low energies (below 100 MeV) for the elements ³He, ²⁰Ne, ⁴⁰Ar, ¹⁴N, ¹²C, and for the ²⁰⁸Pb using a finite electromagnetic potential, which is obtained by considering a Randall–Sundrum II scenario modified by the inclusion of p compact extra-dimensions. The length scale is adjusted in the potential to compare with known experimental data and to set bounds for the parameter of the model. The effective four-dimensional (4D) electromagnetic potential is produced by a point charge, as seen from the three-brane that contains it, in uniform motion in an RSIIp scenario.

Holmium 163 offers perhaps the best chance to determine the neutrino mass by electron capture (EC). This contribution treats the EC in Holmium completely relativistic for the overlap and exchange corrections and the description of the bolometer spectrum. The theoretical expressions are derived consistently in second quantization with the help of Wickʼs theorem assuming single Slater determinants for the initial Ho and the final Dy atoms with holes in the final and states. One needs no hand waving arguments to derive the exchange terms. It seems, that for the first time the multiplicity of electrons in the orbital overlaps are included in the numerical treatment. Electron capture is proportional to the probability to find the captured electron in the parent atom at the nucleus. Non-relativistically this is only possible for electron states. Relativistically also electrons have a probability due to the lower part of the relativistic electron spinor, which does not disappear at the origin. Moreover relativistic effects increase by contraction the electron probability at the nucleus. Capture from other states are suppressed. However they can be allowed with smaller intensity due to finite nuclear size. These probabilities are at least three orders smaller than the EC from and states. The purpose of this work is to give a consistent relativistic formulation and treatment of the overlap and exchange corrections for EC in Ho to excited atomic states in Dy and to show the influence of the different configurations in the final Dy states. The overlap and exchange corrections are essential for the calorimetric spectrum of the de-excitation of the hole states in dysprosium. The slope of the upper end of the spectrum, which contains the information on the electron neutrino mass, is different. In addition the effect of the finite energy resolution on the spectrum and on the determination of the neutrino mass is studied. The neutrino mass must finally be determined by maximum likelihood methods to fit the theoretical spectra at the upper end near the Q value varying the neutrino mass, the Q-value and probably also the energy resolution, because at the moment Q and the energy resolution are not known to the accuracy needed.

A detailed partial wave analysis of the breakup of ¹⁹C on ²⁰⁸Pb at 67 MeV/A is performed to investigate the effects of the nuclear and Coulomb breakups. It is first shown that the breakup cross sections are dominated by p-waves, but all the outgoing neutrons are not necessarily in the p-waves. The contributions of the other partial waves are important and account for the normalization of the breakup cross section. The nuclear contribution is not negligible for angles below and in fact both nuclear and Coulomb breakups contribute equally between and . The incoherent difference of the full (coherent sum of nuclear and Coulomb breakups) and nuclear breakup cross sections agree with the data for low excitation energies. However, the full breakup cross section alone describes well the data for high excitation energies. We found that the small nuclear contribution does not directly imply small nuclear–Coulomb interferences, which was generally found to be destructive regardless whether the continuum–continuum couplings are included or not.