Magnetic interaction induced by the anomaly in kaon-photoproductions

We study the role of magnetic interaction in the photoproduction of the kaon and hyperon. We find that the inclusion of a higher order diagram induced by the Wess-Zumio-Witten term has a significant contribution to the magnetic amplitude, which is compatible to the observed photon asymmetry in the forward angle region. This enables us to use the K^* coupling constants which have been determined in a microscopic way rather than the phenomenological ones which differ largely from the microscopic ones.Comment: 8 pages, 3 figure

Forward-angle K+ Lambda photoproduction in a Regge-plus-resonance approach

We present an effective-Lagrangian description for forward-angle K+ Lambda photoproduction from the proton, valid for photon lab energies from threshold up to 16 GeV. The high-energy part of the amplitude is modeled in terms of t-channel Regge-trajectory exchange. The sensitivity of the calculated observables to the Regge-trajectory phase is investigated in detail. The model is extended towards the resonance region by adding a number of s-channel resonances to the t-channel background. The proposed hybrid ``Regge-plus-resonance'' (RPR) approach allows one to exploit the p(gamma,K+)Lambda data in their entirety, resulting in stronger constraints on both the background and resonance couplings. The high-energy data can be used to fix the background contributions, leaving the resonance couplings as the sole free parameters in the resonance region. We compare various implementations of the RPR model, and explore to what extent the description of the data can be improved by introducing the ``new'' resonances D13(1900) and P11(1900). Despite its limited number of free parameters, the proposed RPR approach provides an efficient description of the p(gamma,K+)Lambda dynamics in and beyond the resonance region.Comment: 31 pages, 9 figures, accepted for publication in PRC. Section IIIB modified to include the most recent data; discussion of results and conclusions changed accordingl

Regge-plus-resonance treatment of the p(gamma,K^+)Sigma^0 and p(gamma,K^0)Sigma^+ reactions at forward kaon angles

An effective-Lagrangian framework for K Sigma photoproduction from the proton is presented. The proposed model is applicable at forward kaon angles and photon lab energies from threshold up to 16 GeV. The high-energy part of the p(gamma,K^+)Sigma^0 and p(gamma,K^0)Sigma^+ amplitudes is expressed in terms of Regge-trajectory exchange in the t channel. By supplementing this Regge background with a number of s-channel resonances, the model is extended towards the resonance region. The resulting ``Regge-plus-resonance'' (RPR) approach has the advantage that the background contributions involve only a few parameters, which can be largely constrained by the high-energy data. This work compares various implementations of the RPR model, and explores which resonance contributions are required to fit the data presently at hand. It is demonstrated that, through the inclusion of one K and two K* trajectories, the RPR framework provides an efficient and unified description of the K^+ Sigma^0 and K^0 Sigma^+ photoproduction channels over an extensive energy range.Comment: 33 pages, 15 figures; added discussion on new double-polarization data (Cx and Cz) in Section I

Electric and magnetic form factors of strange baryons

Predictions for the electromagnetic form factors of the Lambda$, Sigma and Xi hyperons are presented. The numerical calculations are performed within the framework of the fully relativistic constituent-quark model developed by the Bonn group. The computed magnetic moments compare favorably with the experimentally known values. Most magnetic form factors G_M(Q^2) can be parametrized in terms of a dipole with cutoff masses ranging from 0.79 to 1.14 GeV.Comment: 15 pages, 8 figures, 3 tables, submitted to Eur. Phys. J.

Comparison of methods to estimate the affected body surface area and the dosage of topical treatments in psoriasis and atopic dermatitis : the advantage of a picture‐based tool

Background: The accurate determination of the dosage of topical treatments is important given its repercussions on patient adherence and therapeutic efficacy. Up till now, the fingertip unit calculated by the rule of hands is considered the gold standard, although its use is associated with several drawbacks. Objective: To compare different methods to estimate the affected body surface area (BSA) and dosage of topical treatments in atopic dermatitis and psoriasis and investigate its reliability, user-friendliness and timing. Methods: In this study, we compared the reliability of three different methods: (i) the fingertip unit calculated by the 1% hand rule; (ii) a picture-based tool [termed Cutaneous Inflammatory Disease Extent Score (CIDES)]; and (iii) a digital drawing tool. Eleven observers scored 40 patients with psoriasis and eczema to assess the inter-rater and intrarater reliability. Timing was automatically recorded, and user-friendliness was investigated by a questionnaire. Results: An excellent intraclass correlation (ICC) was found for both inter-rater agreement and intrarater agreement for the picture-based tool (ICC = 0.92 and ICC = 0.96, respectively). The ICCs for drawing the area of involvement on a silhouette were 0.89 and 0.93, respectively. Finally, the rule of hands was associated with an increased inter-rater variability although an excellent intrarater agreement was found (ICC = 0.79 and 0.95, respectively). Automated calculation of the amount of topical treatment improved reliability, and CIDES was associated with the least variation. CIDES was considered the preferred method by all observers and was fast to perform (median: 30 s). Conclusion: A picture-based method offered the most advantages (in terms of reliability, speed and user-friendliness) to estimate the affected BSA and calculate the dosage of topical treatments

Exclusive electroproduction of K+ Lambda and K+ Sigma^0 final states at Q^2 = 0.030-0.055 (GeV/c)^2

Cross section measurements of the exclusive p(e,e'K+)Lambda,Sigma^0 electroproduction reactions have been performed at the Mainz Microtron MAMI in the A1 spectrometer facility using for the first time the Kaos spectrometer for kaon detection. These processes were studied in a kinematical region not covered by any previous experiment. The nucleon was probed in its third resonance region with virtual photons of low four-momenta, Q^2= 0.030-0.055 (GeV/c)^2. The MAMI data indicate a smooth transition in Q^2 from photoproduction to electroproduction cross sections. Comparison with predictions of effective Lagrangian models based on the isobar approach reveal that strong longitudinal couplings of the virtual photon to the N* resonances can be excluded from these models.Comment: 16 pages, 7 figure