120181374
The study of hypernuclei with heavy ion beams at GSI
The international HypHI collaboration is proposing a hypernuclear spectroscopy with stable heavy ion beams and rare isotope beams at GSI and FAIR in order to study neutron/proton rich hypernuclei and eventually to measure hypernuclear magnetic moments. As Phase 0 of the HypHI project, we propose the feasibility study of heavy ion induced hypernuclear spectroscopy by observing a mesonic weak decay from H Λ 3 , H Λ 4 and He Λ 5 with 6Li beams at 2 A GeV impinging on a 12C target. The physics motivations, experimental setup and the expected results will be discussed.
15509349
Performance of hpge detectors in high magnetic fields
Abstract A new generation of high-resolution hypernuclear γ -spectroscopy experiments with high-purity germanium detectors (HPGe) are presently designed at the FINUDA spectrometer at DA Φ NE, the Frascati φ -factory, and at P ¯ ANDA , the p ¯ p hadron spectrometer at the future FAIR facility. Both, the FINUDA and P ¯ ANDA  spectrometers are built around the target region covering a large solid angle. To maximise the detection efficiency the HPGe detectors have to be located near the target, and therefore they have to be operated in strong magnetic fields ( B ≈ 1 T ). The performance of HPGe detectors in such an environment has not been well investigated so far. In the present work VEGA and EUROBALL Cluster HPGe detectors were tested in the field provided by the ALADiN magnet at GSI. No significant degradation of the energy resolution was found, and a change in the rise time distribution of the pulses from preamplifiers was observed. A correlation between rise time and pulse height was observed and is used to correct the measured energy, recovering the energy resolution almost completely. Moreover, no problems in the electronics due to the magnetic field were observed.
9594769
108Sn Studied with Intermediate-energy Coulomb Excitation
The unstable neutron-deficient Sn-108 isotope has been studied in inverse kinematics by intermediate-energy Coulomb excitation using the RISING/FRS experimental setup at GSI. This is the highest Z nucleus studied so far with this method. Its reduced transition probability B (E2;0(g.s.)(+)-> 2(1)(+)) has been measured for the first time. The extracted B(E2) value of 0.230(57)e(2) b(2) has been determined relative to the known value in the stable Sn-112 isotope. The result is discussed in the framework of recent large-scale shell model calculations performed with realistic effective interactions. The roles of particle-hole excitations of the Sn-100 core and of the Z=50 shell gap for the E2 polarization are investigated.
59289125
QCD Vacuum in the Strong External Fields
In the very strong external gauge field the QCD true vacuum is shown to have lower energy than the "perturbative vacuum." By using the same calculation a possibility of restoration of the spontaneously broken chiral symmetry of the vacuum is pointed out.
119556872
Noncommutative quantum mechanics and the Seiberg-Witten map
In order to overcome ambiguity problem on identification of mathematical objects in noncommutative theory with physical observables, quantum mechanical system coupled to the NC U(1) gauge field in the noncommutative space is reformulated by making use of the unitarized Seiberg-Witten map, and applied to the Aharonov-Bohm and Hall effects of the NC U(1) gauge field. Retaining terms only up to linear order in the NC parameter \theta, we find that the AB topological phase and the Hall conductivity have both the same formulas as those of the ordinary commutative space with no \theta-dependence.
119781535
Holomorphic geometry of interacting strings
Abstract We apply the geometric quantization of Bowick and Rajeev to interacting bosonic strings. We calculate the total curvature of the two bundles over Diff S 1 /S 1 . The requirement of vanishing of the total curvature leads not only to the critical dimension d =26, but also to constraint equations for vertex operators. We find two solutions to these equations for external scalar fields which are interacting with the open string. Other interactions with a vector field, a weak gravitational field and so on are also discussed.
197519229
Gravity and Discrete Symmetry
Using the differential calculus on discrete group, we study the general relativity in the space-time which is the product of a four dimensional manifold by a two-point space. We generalize the usual concept of frame and connection in our space-time, and from the generalized torsion free condition we obtain an action of a scalar field coupled to Einstein gravity, which may be related to the Jordan-Brans-Dicke theory.
122084216
Operator Formalism of the Dual Resonance Model with Different Trajectories
In the dual resonance model the generalized harmonic oscillator formalism is constructed when relevant particles lie on different trajectories. Requiring the factorization in the sense of the operator method, one can see that the Regge intercepts are expressed in terms of quark quantum numbers. Propagator, general vertex, gauge operator and so on, appearing in the usual dual resonance model with a single trajectory, are redefined. The duality of the four­ point tree diagram between general non-spurious virtual states can also be shown.