Search results for "Vector"
showing 10 items of 2660 documents
Neutron-proton pairing in rotating N ∼ Z nuclei: dominance of the isovector component
2004
Theoretical calculations of rotating N ≈ Z nuclei with A = 58 − 80 within the cranked Nilsson+Strutinsky approach, cranked relativistic mean field and cranked relativistic Hartree+Bogoliubov theories show good agreement with experiment. They point on the presence of the isovector t = 1 np -pairing, but do not show any indications of the isoscalar t = 0 np -pairing.
Evidence for isovector neutron-proton pairing from high-spin states inN=Z74Rb
2003
High-spin states in the odd-odd N=Z nucleus Rb-74(37)37 were studied using the Ca-40(Ca-40,alphanp) reaction. A previously observed odd-spin T=0 band has been extended to I-pi=(31(+)) and an even-spin T=0 band has been observed for the first time to I-pi=(22(+)); both have a pi(g(9/2))circle timesnu(g(9/2)) structure. A strongly coupled low-spin T=0,K=3 band has been interpreted as being based upon a pi[312]3/2 circle timesnu[312]3/2 configuration. Cranked relativistic Hartree-Bogoliubov calculations, which are corrected for the t=1 np-pair field by restoring isospin symmetry, reproduce the observed spectrum. These new results provide evidence for the existence of an isovector pair field th…
Silicon detectors for forward tracking in ATLAS
1996
Abstract A 12 cm long silicon microstrip detector module with a fan geometry has been designed and constructed. The performance of the detector has been studied in a test beam at CERN. Results are presented on the hit efficiency and the position resolution as a function of position along the strips. With a hit efficiency of 99.5% and a spatial resolution of typically 35 μm the performance of these detectors exceeds that of other candidate technologies for the precision forward tracker of the ATLAS inner detector.
Inclusive muon capture in light nuclei
1998
We study total muon capture rates in light nuclei, taking into account renormalizations of the nuclear vector and axial vector strengths. We estimate the influence in the results of uncertainties of the spin-isospin interaction parameter and nuclear densities. A few of these reactions are theoretical benchmarks for physics involving searches for neutrino oscillations. New experiments in muon capture in several targets are suggested, in the light of some discrepancies with theory, crudeness of some experimental results and relevance to neutrino physics.
Sweeping the Space of Admissible Quark Mass Matrices
2002
We propose a new and efficient method of reconstructing quark mass matrices from their eigenvalues and a complete set of mixing observables. By a combination of the principle of NNI (nearest neighbour interaction) bases which are known to cover the general case, and of the polar decomposition theorem that allows to convert arbitrary nonsingular matrices to triangular form, we achieve a parameterization where the remaining freedom is reduced to one complex parameter. While this parameter runs through the domain bounded by a circle with radius R determined by the up-quark masses around the origin in the complex plane one sweeps the space of all mass matrices compatible with the given set of d…
Study of the J/ψ→ϕ(ω)f2(1270), J/ψ→ϕ(ω)f2′(1525) and J/ψ→K∗0(892)K¯2∗0(1430) decays
2009
Abstract We present an approach to study the decay modes of the J / ψ into a vector meson and a tensor meson, taking into account the nature of the f 2 ( 1270 ) , f 2 ′ ( 1525 ) , K ¯ 2 ∗ 0 ( 1430 ) resonances as dynamically generated states from the vector meson-vector meson interaction. We evaluate four ratios of partial decay widths in terms of a flavor dependent OZI breaking parameter and the results obtained compare favorably with experiment, although the experimental uncertainties are still large. Further refinements of the data would provide a more stringent test on the theoretical approach. The fit to the data is possible due to the particular strength and sign of the couplings of t…
Case in favor of theN*(1700)(3/2−)
2013
Using an interaction extracted from the local hidden-gauge Lagrangians, which brings together vector and pseudoscalar mesons, and the coupled channels rho N (s wave), pi N (d wave), pi Delta (s wave), and pi Delta (d wave), we look in the region ofv root s = 1400-1850 MeV and find two resonances dynamically generated by the interaction of these channels, which are naturally associated to N*(1520)(3/2(-)) and N*(1700)(3/2(-)). N*(1700)(3/2(-)) appears neatly as a pole in the complex plane. The free parameters of the theory are chosen to fit the pi N (d-wave) data. Both the real and imaginary parts of the pi N amplitude vanish in our approach in the vicinity of this resonance, which is simila…
Photoproduction of K∗ for the study of Λ(1405)
2004
Abstract The photo-induced K ∗ vector meson production is investigated for the study of the Λ(1405) resonance. This reaction is particularly suited to the isolation of the second pole in the Λ(1405) region which couples dominantly to the K N channel. We obtain the mass distribution of the Λ(1405) which peaks at 1420 MeV, and differs from the nominal one. Combined with several other reactions, like the π−p→K0πΣ which favours the first pole, this detailed study will reveal a novel structure of the Λ(1405) state.
The χ decay to ϕK⁎K¯,ϕh1(1380) testing the nature of axial vector meson resonances
2019
Abstract We perform a theoretical study of the χ c J → ϕ K ⁎ K ¯ → ϕ K π K ¯ reaction taking into account the K ⁎ K ¯ final state interaction, which in the chiral unitary approach is responsible, together with its coupled channels, for the formation of the low lying axial vector mesons, in this case the h 1 ( 1380 ) given the selection of quantum numbers. Based on this picture we can easily explain why in the χ c 0 decay the h 1 ( 1380 ) resonance is not produced, and, in the case of χ c 1 and χ c 2 decay, why a dip in the K + π 0 K − mass distribution appears in the 1550-1600 MeV region, that in our picture comes from a destructive interference between the tree level mechanism and the resc…
ATLAS level-1 calorimeter trigger: subsystem tests of a Jet/Energy-sum Processor module
2003
The ATLAS Level-1 Calorimeter Trigger consists of a Preprocessor, a Cluster Processor (CP), and a Jet/Energy-sum Processor (JEP). The CP and JEP receive digitised trigger-tower data from the Preprocessor and produce trigger multiplicities and total and missing energy for the final trigger decision. The trigger will also provide region-of-interest (RoI) information for the Level-2 trigger and intermediate results of the data acquisition (DAQ) system for monitoring and diagnostics by using readout driver modules (ROD). The Jet/Energy-sum Processor identifies and localises jets, and sums total and missing transverse energy information from the trigger data. The Jet/Energy Module (JEM) is the m…