Precise proton and neutron form factor measurements at Jefferson Lab, using spin observables, have recently made a significant contribution to the unraveling of the internal structure of the nucleon. ...Accurate experimental measurements of the nucleon form factors are a test-bed for understanding how the nucleon’s static properties and dynamical behavior emerge from QCD, the theory of the strong interactions between quarks. There has been enormous theoretical progress, since the publication of the Jefferson Lab proton form factor ratio data, aiming at reevaluating the picture of the nucleon. We will review the experimental and theoretical developments in this field and discuss the outlook for the future.
Probing Cold Dense Nuclear Matter Subedi, R; Shneor, R; Monaghan, P ...
Science (American Association for the Advancement of Science),
06/2008, Letnik:
320, Številka:
5882
Journal Article
Recenzirano
Odprti dostop
The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, in which a proton is knocked out of the nucleus with high-momentum transfer and high missing ...momentum, show that in carbon-12 the neutron-proton pairs are nearly 20 times as prevalent as proton-proton pairs and, by inference, neutron-neutron pairs. This difference between the types of pairs is due to the nature of the strong force and has implications for understanding cold dense nuclear systems such as neutron stars.
Measurements of the production of forward jets from transversely polarized proton collisions at s=500 GeV conducted at the Relativistic Heavy Ion Collider (RHIC) are reported. Our measured jet cross ...section is consistent with hard scattering expectations. Our measured analyzing power for forward jet production is small and positive, and provides constraints on the Sivers functions that are related to partonic orbital angular momentum through theoretical models.
Septic pulmonary embolism is a serious but uncommon syndrome posing diagnostic challenges because of its broad range of clinical presentation and etiologies.
To understand the clinical and ...radiographic associations of septic pulmonary embolism in patients presenting to an acute care safety net hospital.
We conducted a retrospective analysis of imaging and electronic health records of all patients diagnosed with septic pulmonary embolism in our hospital between January 2000 and January 2013.
41 episodes of septic pulmonary embolism were identified in 40 patients aged 17 to 71 years (median 46); 29 (72%) were men. Presenting symptoms included: febrile illness (85%); pulmonary complaints (66%) including pleuritic chest pain (22%), cough (19%) and dyspnea (15%); and those related to the peripheral foci of infection (24%) and shock (19%). Sources of infection included: skin and soft tissue (44%); infective endocarditis (27%); and infected peripheral deep venous thrombosis (17%). 35/41 (85%) were bacteremic with staphylococcus aureus. All patients had peripheral nodular lesions on chest CT scan. Treatment included intravenous antibiotics in all patients. Twenty six (63%) patients required pleural drainage and/or drainage of peripheral abscesses. Seven (17%) patients received systemic anticoagulants. Eight (20%) patients died due to various complications.
The epidemiology of septic pulmonary embolism has broadened over the past decade with an increase in identified extrapulmonary, non-cardiac sources. In the context of an extrapulmonary infection, clinical features of persistent fever, bacteremia and pulmonary complaints should raise suspicion for this syndrome, and typical findings on the chest CT scans confirm the diagnosis. Antibiotics, local drainage procedures and increasingly, anticoagulation are keys to successful outcomes.
The analyzing powers for proton elastic scattering (
p
A
→
p
X
) and neutron charge exchange (
n
A
→
p
X
) reactions on nuclei have been measured on
C
,
CH
,
C
H
2
and
Cu
targets at incident neutron ...momenta 3.0–4.2 GeV/c by detecting one charged particle in forward direction. The polarized neutron measurements are the first of their kind. The experiment was performed using the Nuclotron accelerator in JINR Dubna, where polarized neutrons and protons were obtained from break-up of a polarized deuteron beam which has a maximum momentum of 13 GeV/c. The polarimeter ALPOM2 was used to obtain the analyzing power dependence on the transverse momentum of the final-state nucleon. These data have been used to estimate the figure of merit of a proposed experiment at Jefferson Laboratory to measure the recoiling neutron polarization in the quasi-elastic
2
H
(
e
,
e
′
n
)
reaction, which yields information on the charge and magnetic elastic form factors of the neutron.
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