94 research outputs found
Search for Exotic Mesons in pi- P Interactions at 18 GeV/c
The recent search for non mesons in interactions at
Brookhaven National Laboratory is summarized. Many final states such as , , , , , ,
which are favored decay modes of exotics, are under investigation.Comment: 9 pages, PostScript, Presented at the International School of Nuclear
Physics, Erice, Sicily, Italy, September 199
Observation of a New J(PC)=1(+-) Isoscalar State in the Reaction Pi- Proton -> Omega Eta Neutron at 18 GeV/c
Results are presented on a partial wave analysis of the Omega Eta final state
produced in Pi- Proton interactions at 18 GeVc where Omega -> Pi+ Pi- Pi0, Pi0
-> 2 Gammas, and Eta -> 2 Gammas. We observe the previously unreported decay
mode Omega(1650) -> Omega Eta and a new 1(+-) meson state h1(1595) with a mass
M=1594(15)(+10)(-60) MeV/c^2 and a width Gamma=384(60)(+70)(-100) MeV/c^2. The
h1(1595) state exhibits resonant-like phase motion relative to the Omega(1650).Comment: Submitted to Physics Letters B Eight total pages including 11 figures
and 1 tabl
A partial wave analysis of the system produced in charge exchange collisions
A partial wave analysis of the of the system produced in the
charge exchange reaction: at an incident momentum of
is presented as a function of invariant mass,
, and momentum transfer squared, , from the incident
to the outgoing system.Comment: 24 pages total,8 pages text, 14 figures, 1 table. Submitted to Phys
Rev
The -dependence of the generalised Gerasimov-Drell-Hearn integral for the deuteron, proton and neutron
The Gerasimov-Drell-Hearn (GDH) sum rule connects the anomalous contribution
to the magnetic moment of the target nucleus with an energy-weighted integral
of the difference of the helicity-dependent photoabsorption cross sections. The
data collected by HERMES with a deuterium target are presented together with a
re-analysis of previous measurements on the proton. This provides a measurement
of the generalised GDH integral covering simultaneously the nucleon-resonance
and the deep inelastic scattering regions. The contribution of the
nucleon-resonance region is seen to decrease rapidly with increasing . The
DIS contribution is sizeable over the full measured range, even down to the
lowest measured . As expected, at higher the data are found to be in
agreement with previous measurements of the first moment of . From data on
the deuteron and proton, the GDH integral for the neutron has been derived and
the proton--neutron difference evaluated. This difference is found to satisfy
the fundamental Bjorken sum rule at GeV.Comment: 12 pages, 10 figure
Observation of a Coherence Length Effect in Exclusive Rho^0 Electroproduction
Exclusive incoherent electroproduction of the rho^0(770) meson from 1H, 2H,
3He, and 14N targets has been studied by the HERMES experiment at squared
four-momentum transfer Q**2>0.4 GeV**2 and positron energy loss nu from 9 to 20
GeV. The ratio of the 14N to 1H cross sections per nucleon, known as the
nuclear transparency, was found to decrease with increasing coherence length of
quark-antiquark fluctuations of the virtual photon. The data provide clear
evidence of the interaction of the quark- antiquark fluctuations with the
nuclear medium.Comment: RevTeX, 5 pages, 3 figure
Determination of the Deep Inelastic Contribution to the Generalised Gerasimov-Drell-Hearn Integral for the Proton and Neutron
The virtual photon absorption cross section differences [sigma_1/2-sigma_3/2]
for the proton and neutron have been determined from measurements of polarised
cross section asymmetries in deep inelastic scattering of 27.5 GeV
longitudinally polarised positrons from polarised 1H and 3He internal gas
targets. The data were collected in the region above the nucleon resonances in
the kinematic range nu < 23.5 GeV and 0.8 GeV**2 < Q**2 < 12 GeV**2. For the
proton the contribution to the generalised Gerasimov-Drell-Hearn integral was
found to be substantial and must be included for an accurate determination of
the full integral. Furthermore the data are consistent with a QCD
next-to-leading order fit based on previous deep inelastic scattering data.
Therefore higher twist effects do not appear significant.Comment: 6 pages, 3 figures, 1 table, revte
Principles of the Field Theory of High Temperature Superconductivity in Underdoped Copper-Oxides
Here I extend my last work about the origin of the pseudo-gaps in underdoped
cuprates (arXiv: cond-mat. 1011.3206), to include the mechanism of
superconductivity. This is done by adapting the formalism of the double
correlations in systems with nested Fermi surfaces to the semi one dimensional
system of strings of holes. It is proposed that magnetic interaction is crucial
for the establishment of the pseudogap and the high temperature
superconductivity. It is shown that superconductivity disturbs the completeness
of the strings of holes, and creates fluctuations in their shapes. This, in
turn, reduces the magnetic interaction and the pseudogap order.Comment: This paper has been withdrawn by the author. 27 page
A Theory for the High-T_c Cuprates: Anomalous Normal-State and Spectroscopic Properties, Phase Diagram, and Pairing
A theory of highly correlated layered superconducting materials isapplied for
the cuprates. Differently from an independent-electron approximation, their
low-energy excitations are approached in terms of auxiliary particles
representing combinations of atomic-like electron configurations, where the
introduction of a Lagrange Bose field enables treating them as bosons or
fermions. The energy spectrum of this field accounts for the tendency of
hole-doped cuprates to form stripe-like inhomogeneities. Consequently, it
induces a different analytical behavior for auxiliary particles corresponding
to "antinodal" and "nodal" electrons, enabling the existence of different
pairing temperatures at T^* and T_c. This theory correctly describes the
observed phase diagram of the cuprates, including the non-Fermi-liquid to FL
crossover in the normal state, the existence of Fermi arcs below T^* and of a
"marginal-FL" critical behavior above it. The qualitative anomalous behavior of
numerous physical quantities is accounted for, including kink- and
waterfall-like spectral features, the drop in the scattering rates below T^*
and more radically below T_c, and an effective increase in the density of
carriers with T and \omega, reflected in transport, optical and other
properties. Also is explained the correspondence between T_c, the
resonance-mode energy, and the "nodal gap".Comment: 28 pages, 7 figure
Search for 14.4 keV Solar Axions from M1 Transition of 57Fe with CUORE Crystals
We report the results of a search for axions from the 14.4 keV M1 transition from 57Fe in the core of the sun using the axio-electric effect in TeO2bolometers. The detectors are 5
× 5 × 5 cm3 crystals operated at about 10 mK in a facility used to test bolometers for the CUORE experiment at the Laboratori Nazionali del Gran Sasso in Italy. An analysis of 43.65 kg⋅d of data was made using a newly developed low energy trigger which was optimized to reduce the energy threshold of the detector. An upper limit of 0.58 c⋅kg−1⋅d−1 is established at 95% C.L., which translates into lower bounds fA ≥ 3.12 × 105 GeV 95% C.L. (DFSZ model) and fA ≥ 2.41 × 104 GeV 95% C.L. (KSVZ model) on the Peccei-Quinn symmetry-breaking scale, for a value of S = 0.5 of the flavor-singlet axial vector matrix element. These bounds can be expressed in terms of axion masses as mA ≤ 19.2 eV and mA ≤ 250 eV at 95% C.L. in the DFSZ and KSVZ models respectively. Bounds are given also for the interval 0.35 ≤ S ≤ 0.55
Search for 14.4 keV Solar Axions from M1 Transition of 57Fe with CUORE Crystals
We report the results of a search for axions from the 14.4 keV M1 transition from 57Fe in the core of the sun using the axio-electric effect in TeO2bolometers. The detectors are 5
× 5 × 5 cm3 crystals operated at about 10 mK in a facility used to test bolometers for the CUORE experiment at the Laboratori Nazionali del Gran Sasso in Italy. An analysis of 43.65 kg⋅d of data was made using a newly developed low energy trigger which was optimized to reduce the energy threshold of the detector. An upper limit of 0.58 c⋅kg−1⋅d−1 is established at 95% C.L., which translates into lower bounds fA ≥ 3.12 × 105 GeV 95% C.L. (DFSZ model) and fA ≥ 2.41 × 104 GeV 95% C.L. (KSVZ model) on the Peccei-Quinn symmetry-breaking scale, for a value of S = 0.5 of the flavor-singlet axial vector matrix element. These bounds can be expressed in terms of axion masses as mA ≤ 19.2 eV and mA ≤ 250 eV at 95% C.L. in the DFSZ and KSVZ models respectively. Bounds are given also for the interval 0.35 ≤ S ≤ 0.55
- …