106 research outputs found
Khuri-Treiman equations for 3π decays of particles with spin
No full textKhuri-Treiman equations have proven to be a useful theoretical tool in the analysis of three-body decays, especially into the 3π final state. In this work we present in full detail the necessary generalization of the formalism to study the decays of particles with arbitrary spin, parity, and charge conjugation. To this extent, we find it most convenient to work with helicity amplitudes instead of the so-called invariant amplitudes, especially when dealing with the unitarity relations. The isobar expansions in the three possible (s-, t-, and u-) final channels are related with the appropriate crossing matrices. We pay special attention to the kinematical singularities and constraints of the helicity amplitudes, showing that these can be derived by means of the crossing matrix
Double polarization observables in pentaquark photoproduction
No full textWe investigate the properties of the hidden-charm pentaquark-like resonances first observed by the LHCb Collaboration in 2015, by measuring the polarization transfer K-LL between the incident photon and the outgoing proton in the exclusive photoproduction of J/psi near threshold. We present a first estimate of the sensitivity of this observable to the pentaquark photocouplings and hadronic branching ratios, and extend our predictions to the case of the initial-state helicity correlation A(LL), using a polarized target. These results serve as a benchmark for the SBS experiment at Jefferson Lab, which proposes to measure for the first time the helicity correlations A(LL) and K-LL in J/psi exclusive photoproduction, in order to determine the pentaquark photocouplings and branching ratios
Dalitz-plot decomposition for three-body decays
No full textWe present a general formalism to write the decay amplitude for multibody reactions with explicit separation of the rotational degrees of freedom, which are well controlled by the spin of the decay particle, and dynamic functions on the subchannel invariant masses, which require modeling. Using the three-particle kinematics we demonstrate the proposed factorization, named the Dalitz-plot decomposition. The Wigner rotations, which are subtle factors needed by the isobar modeling in the helicity framework, are simplified with the proposed decomposition. Consequently, we are able to provide them in an explicit form suitable for the general case of arbitrary spins. The only unknown model-dependent factors are the isobar line shapes that describe the subchannel dynamics. The advantages of the new decomposition are shown through three examples relevant for the recent discovery of the exotic charmonium candidate Zc(4430), the pentaquarks Pc, and the intriguing Λc+→pK-π+ decay
Khuri-Treiman equations for decays of particles with spin
No full textKhuri-Treiman equations have proven to be a useful theoretical tool in the analysis of three-body decays, especially into the 3π final state. In this work we present in full detail the necessary generalization of the formalism to study the decays of particles with arbitrary spin, parity, and charge conjugation. To this extent, we find it most convenient to work with helicity amplitudes instead of the so-called invariant amplitudes, especially when dealing with the unitarity relations. The isobar expansions in the three possible (s-, t-, and u-) final channels are related with the appropriate crossing matrices. We pay special attention to the kinematical singularities and constraints of the helicity amplitudes, showing that these can be derived by means of the crossing matrix.Khuri-Treiman equations have proven to be a useful theoretical tool in the analysis of 3-body decays, specially into the final state. In this work we present in full detail the necessary generalization of the formalism to study the decays of particles with arbitrary spin, parity, and charge conjugation. To this extent, we find it most convenient to work with helicity amplitudes instead of the so-called invariant amplitudes, specially when dealing with the unitarity relations. The isobar expansions in the three possible (-, -, and -) final channels are related with the appropriate crossing matrices. We pay special attention to the kinematical singularities and constraints of the helicity amplitudes, showing that these can be derived by means of the crossing matrix
Mulberry harbour 1944-1994
No full textOverview of the construction of the caissons and the construction of the invasion port at Arromanches in Normandy, France. Includes interviews with the engineers involved
DIETARY INTAKE AND STATUS OF VITAMIN D AND CALCIUM IN PATIENTS WITH CHRONIC RENAL FAILURE (CRF) TREATED BY HAEMODIALYSIS (HD) AT HOME.
No full text
Aluminium–related osteomalacia: response to reverse osmosis water treatment
No full textAluminium–related osteomalacia: response to reverse osmosis water treatment. It is generally accepted that aluminium induces osteomalacia in chronic hemodialysis patients by binding to the calcification front, thereby inhibiting mineralization of osteoid. Because this form of osteomalacia is vitamin D resistant, the condition has often been assumed to be irreversible, although promising results have been achieved recently by using a chelating agent for removal of aluminium from the skeleton. In this paper we present four chronic hemodialysis patients with aluminium toxicity and histologic osteomalacia in whom the mineralization defect greatly regressed after the use of reverse osmosis treated–water for dialysis, but without further treatment. In three other patients, also with aluminium toxicity and histologic osteomalacia, similarly treated, the histological severity of the osteomalacia remained static. Those patients in whom bone mineralization status improved developed hyperparathyroidism after reverse osmosis water–treatment, whereas the static patients remained euparathyroid. The results suggest that resolution of alumium related osteomalacia may occur with reduction in dialysis fluid aluminium, and that parathyroid hormone plays a role in the healing of aluminium related osteomalacia. The therapeutic implications are twofold: (1) attempts to remove all traces of hyperparathyroidism may be detrimental to the bone mineralization status; and (2) stimulation of the parathyroid glands by means of a mild reduction in dialysis fluid calcium may be of value in the management of those cases with persistent osteomalacia and low bone turnover
Increased resolution within Y-chromosome haplogroup R1b M268 shed light on the neolithic transition in Europe
No full textIs Dupuytren’s disease really a “disease of the Vikings”?
No full textIt has been suggested that Dupuytren’s Disease has an origin in Norse countries. We harnessed data from a genome-wide association study of Dupuytren’s Disease and the People of the British Isles study to determine evidence for a Norse origin of Dupuytren’s Disease. We computed Wright’s Fixation Index between Orkney (Norse ancestry), Wales (ancient British) and South East England (Anglo-Saxons); compared mean Wright’s Fixation Index in cases versus controls; used permutation to determine any excess of Norse inheritance in disease associated variants; constructed a genetic risk score for Dupuytren’s Disease and applied this to the People of the British Isles dataset to look for systematic differences between counties with known high and low levels of Norse ancestry. Finally, chromosome painting was used to see whether Dupuytren’s Disease associated single nucleotide polymorphisms are geographically structured. In all analyses, no evidence was found for an excess of Norse ancestry in Dupuytren’s Disease. We conclude that there is no genetic evidence for a “Viking origin of Dupuytren’s Disease”
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