Pion-Proton Scattering below 150 Mev. I

Abstract

Positive-pion proton differential cross sections have been measured at 41.5 Mev for six angles. The angles in the center-of-mass system are 53°, 69.1°, 100.4°, 128°, 141.7°, and 163.5° and the corresponding cross sections in mb/sterad in the center-of-mass system are 0.252±0.020, 0.354±0.025, 0.777±0.038, 1.145 ±0.067, 1.495±0.084, and 1.750=1=0.110. Negative pion elastic cross sections have been measured for the first five of the above angles and are, respectively, in mb/sterad in the cm. system: 0.338=b0.047, 0.281 ±0.038, 0.148±0.029, 0.112±0.042, and 0.085±0.25. Phase-shift analyses of these data and those of other authors lead to the following expressions for the low-energy behavior of the T = f phases: 0:31^= -(0.0418 ±0.004V, a 3 *=-(0.1145±0.0026)? 7 , and co\.a zz N = ^ (0.0877±0.0014)/[co*(l-co*/2.17)].

Numerical study of Hawking radiation photosphere formation around microscopic black holes

“…Thus one might anticipate that the QCD photosphere ends rather abruptly beyond distances of order Λ −1 QCD . To semiquantitatively investigate this posthadronization regime, we modeled the hadron gas by replacing α s by the pion-nucleon fine-structure constant, f 2 /4π ∼ = 0.09, obtained from low-energy pion-nucleon scattering [18]; we also substituted the quark mass with the pion thermal mass, which we estimate analogously to eqs. ( 25) and ( 27).…”

NN¯↔ππAmplitude and the Electromagnetic Structure of the Nucleon

“…We believe that such a combination is more accurate than the (3,3) amplitude alone since the second resonance is probably in the J=3/2 D state. The scattering lengths used are taken from the analysis of Barnes et aL 3 and Hamilton and Woolcock. 4 It is clear that r\(0) is the most accurately determined normalization.…”

“…where (2) is the transition matrix element for the scattering of a (real) photon off a boson, and D." v (q*) is the virtual photon propagator, V* 2)=(1/ * 2)( v~%v* 2) - (3) In Eq. (2) we ignore the vacuum expectation terms which contribute equally to the self-masses of charged and uncharged mesons.…”

OPAL and More

“…These were the fields mostly studied at BNL, CERN, Fermilab, Serpukhov and other lower energy proton accelerator laboratories in the 1960s-1990s and will be studied again at LHC. Hadron-hadron elastic scattering involved first the study of low energy pion-nucleon scattering and of resonances [14]; later it involved the study of the forward diffraction region of higher energy elastic scattering for the six stable charged hadrons (π ± , K ± , p and p on protons [15]): their interpretation was made in the context of Regge poles and trajectories, in particular of the Pomeron trajectory [16].…”