arXiv subjects

H. Ibrahim

Publications and source records attributed to H. Ibrahim.

39 records · Page 3Linked to original sources

arXiv2008

Quark-Hadron Duality in Neutron (3He) Spin Structure

We present experimental results of the first high-precision test of quark-hadron duality in the spin-structure function g_1 of the neutron and $^3$He using a polarized 3He target in the four-momentum-transfer-squared range from 0.7 to 4.0 (GeV/c)^2. Global duality is observed for the spin-structure function g_1 down to at least Q^2 = 1.8 (GeV/c)^2 in both targets. We have also formed the photon-nucleon asymmetry A_1 in the resonance region for 3He and found no strong Q^2-dependence above 2.2 (GeV/c)^2.

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arXiv2006

Towards Applicative Relational Programming

Functional programming comes in two flavours: one where ``functions are first-class citizens'' (we call this applicative) and one which is based on equations (we call this declarative). In relational programming clauses play the role of equations. Hence Prolog is declarative. The purpose of this paper is to provide in relational programming a mathematical basis for the relational analog of applicative functional programming. We use the cylindric semantics of first-order logic due to Tarski and provide a new notation for the required cylinders that we call tables. We define the Table/Relation Algebra with operators sufficient to translate Horn clauses into algebraic form. We establish basic mathematical properties of these operators. We show how relations can be first-class citizens, and devise mechanisms for modularity, for local scoping of predicates, and for exporting/importing relations between programs.

cs.PL↗

arXiv2004

Precision Rosenbluth measurement of the proton elastic form factors

We report the results of a new Rosenbluth measurement of the proton form factors at Q^2 values of 2.64, 3.20 and 4.10 GeV^2. Cross sections were determined by detecting the recoiling proton in contrast to previous measurements in which the scattered electron was detected. At each Q^2, relative cross sections were determined to better than 1%. The measurement focussed on the extraction of G_E/G_M which was determined to 4-8% and found to approximate form factor scaling, i.e. μ_p G_E \approx G_M. These results are consistent with and much more precise than previous Rosenbluth extractions. However, they are inconsistent with recent polarization transfer measurements of comparable precision, implying a systematic difference between the two techniques.

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