3,030 research outputs found
Photoproduction of Pentaquark in Feynman and Regge Theories
Photoproduction of the Theta+ pentaquark on the proton is analyzed by using
an isobar and a Regge models. The difference in the calculated total cross
section is found to be more than two orders of magnitude for a hadronic form
factor cut-off Lambda > 1 GeV. Comparable results would be obtained for 0.6 <
Lambda < 0.8 GeV. We also calculate contribution of the Theta+ photoproduction
to the GDH integral. By comparing with the current phenomenological
calculation, it is found that the GDH sum rule favors the result obtained from
Regge approach and isobar model with small Lambda.Comment: 5 pages, 5 figures, submitted to Phys.Rev.C as a Rapid Communicatio
Extraction of the proton charge radius from experiments
Static properties of hadrons such as their radii and other moments of the
electric and magnetic distributions can only be extracted using theoretical
methods and not directly measured from experiments. As a result, discrepancies
between the extracted values from different precision measurements can exist.
The proton charge radius, , which is either extracted from electron proton
elastic scattering data or from hydrogen atom spectroscopy seems to be no
exception. The value fm extracted from muonic hydrogen
spectroscopy is about 4% smaller than that obtained from electron proton
scattering or standard hydrogen spectroscopy. The resolution of this so called
proton radius puzzle has been attempted in many different ways over the past
six years. The present article reviews these attempts with a focus on the
methods of extracting the radius.Comment: Mini review, 14 pages, 1 figur
Modafinil dependence: A case with attention-deficit/hyperactivity disorder
Modafinil is generally known as a drug with low addiction potential. There are few case reports in the literature demonstrating that Modafinil, stated being capable of diminishing symptoms of attention deficit/hyperactivity disorder (ADHD), causes addiction. In the present article a Modafinil addicted ADHD case, consuming usurious doses (5,000 mg/per day) of Modafinil is presented. The case presented to our psychiatry outpatient clinic due to: requirement of in taking high dose Modafinil in order to achieve the initial effects, difficulty in obtaining the drug, irritability, anxiousness, sleep irregularities, fatigue and unpleasant vivid dreams when he did not use the drug. It was realized that the patient, himself increased doses of Modafinil incrementally, in order to keep its effects on attention symptoms at the same level. It has to be kept in mind that ADHD patients can develop Modafinil addiction. It is necessary to carry out systemic studies on this subject. © 2018 Korean Neuropsychiatric Association
Gerasimov-Drell-Hearn Sum Rule and the Discrepancy between the New CLAS and SAPHIR Data
Contribution of the K^+\Lambda channel to the Gerasimov-Drell-Hearn (GDH) sum
rule has been calculated by using the models that fit the recent SAPHIR or CLAS
differential cross section data. It is shown that the two data sets yield quite
different contributions. Contribution of this channel to the forward spin
polarizability of the proton has been also calculated. It is also shown that
the inclusion of the recent CLAS C_x and C_z data in the fitting data base does
not significantly change the result of the present calculation. Results of the
fit, however, reveal the role of the S_{11}(1650), P_{11}(1710), P_{13}(1720),
and P_{13}(1900) resonances for the description of the C_x and C_z data. A
brief discussion on the importance of these resonances is given. Measurements
of the polarized total cross section \sigma_{TT'} by the CLAS, LEPS, and MAMI
collaborations are expected to verify this finding.Comment: 15 pages, 8 figure
Kaon photoproduction on the nucleon: Contributions of kaon-hyperon final states to the magnetic moment of the nucleon
By using the Gerasimov-Drell-Hearn (GDH) sum rule and an isobaric model of
kaon photoproduction, we calculate contributions of kaon-hyperon final states
to the magnetic moment of the proton and the neutron. We find that the
contributions are small. The approximation of sigma_{TT'} by sigma_{T} clearly
overestimates the value of the GDH integral. We find a smaller upper bound for
the contributions of kaon-hyperon final states to the proton's anomalous
magnetic moment in kaon photoproduction, and a positive contribution for the
square of the neutron's magnetic moment.Comment: 6 pages, revtex, 1 postscript figure, to appear in Phys. Rev.
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