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1.
The threshold behaviour of pion production presented in our earlier work is successfully compared with the new SPEAR data. By using duality and sum rules we derive FT(π+)(x) ≈ FL(π+)(x) ≈ FT(π0)(x) ? FL(π0)(x) for x near 1. An accompanying results is for large s. 相似文献
2.
The dependence of inclusive cross sections of the production of hadrons on p⊥ (and also on x and √s) is calculated at high energy in the region of small p⊥ ? 1–2 GeV. The model of production and decay of quark-gluon strings is used under the simplest assumptions about the k⊥ dependence of the quark distributions in nucleons ~ exp(?γ1k2⊥) and about the form of the string fragmentation function where γ1 and γh are some constants. The theory reproduces all existing experimental data and yields the “seagull effect” for the dependence of 〈p⊥〉 on x. Predictions are given for the p⊥ dependence of the spectra of π± mesons produced at high energies at SPS and other future colliders. 相似文献
3.
K. Böckmann J. Hofmann U. Idschok J. Lowsky B. Schröder V. Blobel H. Fesefeldt R. Schulte G. Kellner D.R.O. Morrison H. Saarikko T. Coghen 《Nuclear Physics B》1980,166(2):284-300
A study is presented of the inclusive production cross sections of K1±(892) vector mesons in pp interactions at 12 and 24 GeV/c and in π+p interactions at 16 GeV/c. The K1± inclusive cross section is ~0.9 mb for both pp at 24 GeV/c and π+p interactions at 16 GeV/c. For pp interactions, and are seen to rise with energy, showing a threshold behaviour. In both pp and π+p interactions, largely exceeds at these energies and this excess is interpreted as K1+ production by beam and target fragmentations. The decays of K1±0 yield ~30% of the K0 observed in the final states. The pT2 dependence of both K1+ and K1? cross sections is described by an exponential with slope of ~3.3 (GeV/c)?2. The longitudinal momentum spectra for K1+ in 16 GeV/cπ+p and 24 GeV/c pp interactions are similar in shape in the target hemisphere. The K1? spectra are similar over the whole kinematic region when viewed in the quark c.m.s. and point to a central production mechanism. Comparing K1+ and ρ0 production, striking similarities are found. 相似文献
4.
A.D. Krisch 《Physics letters. [Part B]》1973,44(1):71-75
The model assumes that when two high energy particles collide each behaves as a geometrical object which has a Gaussian density and is spherically symmetric except for the Lorentz-contraction in the incident direction. Folding the two spatial distribution together we obtain the slope (b) of the elastic diffraction peak in terms of the c.m. velocities (βi and βj) and the sizes (Ai and Aj) of the two incident particles. These sizes are assumed to have the experimental s-dependence of σtot ∝ πA2 for each reaction. The combined s-dependence of the σtot's and the β's gives the s-dependence of the elastic slope . This formula agrees with the experimental slope for p-p, -p, K+-p, K?-p and π±-p elastic scattering from 3 to 1500 GeV/c, with only 3 parameters: Aπ2 = 6.1, AK2 = 3.3 and Ap2 = 10.5 (GeV/c)?2. 相似文献
5.
R.P. Worden 《Physics letters. [Part B]》1974,51(1):57-62
Three independent structure functions of a real photon can be measured in photon-photon collisions in e±e? storage rings. These are M1 and ML (related to the usual structure functions W1andνW2, as defined for any target) and a third function M3, which arises from the strong plane polarisation of the colliding photons. We show, using a dispersion relation in the photon mass, that M3 and the longitudinal structure function ML both scale and are independent of the vector-dominant hadronic structure of the real photon. Therefore in a parton model, or in the quark light-cone algebra, they are given by the bare quark box diagrams which also dominate when both photons have large q2; this uniquely predicts the behaviour , for the real photon structure functions in the Bjorken limit (q22 → ?∞, q12=0, x=?q22/2q1·q2=constant). 相似文献
6.
Recent QCD results on two-particle longitudinal spectra inside quark and gluon jets are extended to the case of a fixed relative transverse momentum qT with Λ ≈ 0.5 GeV ? 2|qT| ? √Q2. Broad qT distributions, especially for gluon jets, are obtained which smooth out automatically the perturbative result and whose integrated versions scale in ηMax ≡ . 相似文献
7.
We have performed an isospin analysis of single-pion production processes in antiproton-nucleon scattering from threshold to 2.90 GeV/c. Reactions used are . Results show that σ1, the total I=1 cross section, rises rapidly from threshold to reach a broad maximum around 2.5 GeV/c and σ0, the I=0 cross section, rises from threshold and continues on a linearly rising trend at least up to 2.90 GeV/c. In the region of 2.9 GeV/c, σ1 and σ0 have comparable values, thus suggesting that considerable amount of and states is produced even in this low momentum region. We further determine that single pion production processes are not the source of the π0 (2375,190) enhancement observed in the and total cross sections and may account for as much as 25±8% of the π1 (2350,140) enhancement. 相似文献
8.
A recently proposed model for dynamical breaking of chiral symmetry in QCD is extended and developed for the calculation of pion and chiral symmetry breaking parameters. The pion is explicitly realized as a massless Goldstone boson and as a bound state of the constituent quarks. We compute, in the limit of exact chiral symmetry, MQ, the constituent quark mass the pion decay coupling, , the constituent quark loop density, μπ2/mq, the ratio of the Goldstone boson mass squared to the bare quark mass, and 〈r2〉π, the pion electromagnetic charge radius squared. 相似文献
9.
B. Ghidini F. Navach A. Palano V. Picciarelli G. Zito J. Bröring K. Müller E. Paul W. Renneberg W. Rühmer J. Eades B. French L. Mandelli J. Moebes M.E. Edwards I. Smith R.A. Donald C. Palazzi-Cerrina 《Nuclear Physics B》1978,132(5):429-438
The reaction , where ps is a slow proton, was measured at 12 GeV/c incident momentum with the CERN-OMEGA spectrometer. Both antiproton and proton were identified uniquely by electronics information. We obtained 1844 events with four-momentum Transfer squared in the range 0.13 ? |t| ? 0.33 GeV2 and with invariant masses up to 2.5 GeV. The corresponding cross section in this t range is determined to be σ = 4 ± 0.4 μb. Extrapolating the differential cross section over the whole t range assuming dσ/dt ≈ exp(5.3t) we estimate a cross section of σ = 9.3 ± 2.0 μb. Comparison with data on (where ns is a slow neutron) in the same t range shows that the cross sections have approximately the same magnitude. 相似文献
10.
A. Berglund T. Buran P.J. Carlson C.J.S. Damerell I. Endo A.R. Gillman V. Gracco R.J. Homer M.J. Hotchkiss A. Lundby M. Macri B.N. Ratcliff A. Santroni T. Tso F. Wickens J.A. Wilson 《Physics letters. [Part B]》1975,57(1):100-104
For the first time, the reactions π+p→K+∑+ and K?p→π?∑+ have been studied in the same apparatus. This has been done at an adequately high momentum (10.1 GeV/c) to allow a check of the prediction of exchange degeneracy, that the differential cross sections should be converging at high energy. We have measured the cross section for momentum transfers t between tmin and t = ?0.3 (GeV/c)2. We find that for both reactions the differential cross section shows an exponential fall, with no deviations right in to t =tmin (where some other experiments have shown a dip in the cross section). Furthermore, we find the magnitude of the differential cross sections to be closely similar at t = 0, with a ratio However, the slope for the positive reaction is about 19% steeper than that for the negative reaction. 相似文献
11.
John Lekner 《Physica A》1982,112(3):544-556
We derive comparison identities for waves satisfying the equation d2Ψ/dz2+q2(z)Ψ=0. One of these identities is used to show that to second order in the product (wavenumber component normal to interface) × (interface thickness), the reflection amplitude is given by , where l is a legnth determined by the deviation of the interface profile from a step, and q1, q2 are the normal components of the wave numbers in media 1 and 2 on either side of the interface. For the continuous interfaces discussed, l is about two-fifths of the 10–90 interface thickness. The corresponding formula for the transmission amplitude is . 相似文献
12.
Yu.M. Antipov V.A. Bessubov N.P. Budanov Yu.P. Gorin S.P. Denisov S.V. Klimenko A.A. Lebedev Yu.V. Mikhailov A.I. Petrukhin S.A. Polovnikov V.N. Roinishvili D.A. Stoyanova F.A. Yotch 《Physics letters. [Part B]》1978,76(2):235-236
The differential cross sections and of inclusive J/ψ production by 43 GeV/c π? off Be, Cu and W nuclei have been measured. Fitting we observed the increase of α with pt2. 相似文献
13.
14.
M.J. Corden J.D. Dowell J. Garvey R.J. Homer M. Jobes I.R. Kenyon T. McMahon R.C. Owen K.C.T.O. Sumorok R.J. Vallance P.M. Watkins J.A. Wilson P. Sonderegger B. Chaurand A. Romana R. Salmeron 《Physics letters. [Part B]》1981,98(3):220-224
J/ψ production at 40 GeV/c by π±, K±, p and incident on hydrogen has been studied and results compared with those obtained on tungsten in the same experiment. On hydrogen, J/ψ cross-section ratios relative to π? have been measured to be (for . The suppression of the proton induced cross sections shows the importance of calence quark-antiquark fusiin J/ψ production at this energy (i.e. MJ2/ψ/s=0.13). 相似文献
15.
The time dependence of microwave absorption was measured for the J = 2-1 and J = 3-2 transitions of OCS under on- and off-resonant conditions utilizing Stark and source modulation, respectively. The two effective pressure parameters obtained under the two conditions, which correspond to and , respectively, according to the Bloch equation, are different beyond experimental error; the difference is 0.94 ± 0.38 (2.5σ) MHz/Torr for J = 2?1. This difference was also determined to be 1.19 ± 0.30 MHz/Torr from the dependence of the nutation frequency on the microwave power. 相似文献
16.
S. Iversen H. Nann A. Obst Kamal K. Seth N. Tanaka C.L. Morris H.A. Thiessen K. Boyer W. Cottingame C. Fred Moore R.L. Boudrie D. Dehnhard 《Physics letters. [Part B]》1979,82(1):51-54
π+ and π? elastic and inelastic scattering from 18O have been measured at T(π)=164 MeV. Consistent with the results at 230 MeV, it is found that the ratio for the 21+ state is 1.86(16), while for the 31? state it is 0.89(6). These results are interpreted as indicating differences in neutron and proton deformations characterizing the 21+ transition and partial neutron blocking for the 31? transition. Optical model analysis of elastic scattering leads to the conclusion that . 相似文献
17.
P. Gregory D. Everett P. Grossmann P. Mason H. Muirhead G. Warren R. Carlsson G. Ekspong S.O. Holmgren S. Nilsson R. Stenbacka C. Walck 《Nuclear Physics B》1974,78(2):222-232
Relations have been derived between the invariant cross sections for various inclusive processes by assuming factorisation of the leading (pomeron) and non-leading (meson) trajectories. In this paper predictions for the invariant cross sections have been tested using data from interactions at 4.6 and 9.1 GeV/c.A large discrepancy between experiment and theory is apparent for the π? data: in the π+ case the discrepancy is less marked but still present. 相似文献
18.
A. Babaev E. Brachman G. Eliseev A. Ermilov Yu. Galaktionov Yu. Gorodkov Yu. Kamishkov E. Leikin V. Lubimov L. Ponomarev V. Shevchenko V. Tiunchik O. Zeldovich V. Böhmer J. Engler W. Flauger H. Keim F. Mönnig H. Schopper 《Nuclear Physics B》1976,116(1):28-50
The diffraction dissociation reaction n + p → (pπ?) + p was studied at the Serpukhov accelerator neutron beam in the momentum range 35–65 GeV/c in an electronics experiment. The differential cross sections of the reaction are analysed and presented in the five-dimensional phase space . The backward peak observed in the distribution over if cosθin GJ 1 in the Gottfried-Jackson frame of if(pπ) is interpreted as a baryon-exchange effect. The angular distribution of the (pπ?) system is compared with Deck-type models. 相似文献
19.
Yu.B. Bushnin A.F. Dunaitsev R.I. Dzelyadin S.V. Golovkin V.F. Konstantinov V.P. Kubarovsky L.G. Landsberg V.M. Leontiev G.P. Makarov V.A. Mukhin V.G. Rybakov T.I. Petrunina Yu.N. Simonov V.V. Smirnov A.M. Zaitsev A. Zallo 《Physics letters. [Part B]》1976,64(1):102-106
The difference of the cross sections for deep inelastic scattering of muons with average momenta 21 GeV/c with right and left helicity at large angles, i.e., with large momentum transfer, has been measured. No statistically-significant dependence of cross sections on the longitudinal polarization of muons has been found, i.e. no parity-nonconservation effects in deep inelastic μN interaction have been observed. The magnitude of the cross-section asymmetry may be represented as R = β〈Q2〉 = (? 4 ± 6) × 10?3 〈Q2, (GeV/c)2〉. The limitations Go(μ) = (+ 6 ± 10)G have been obtained for the constant Go(μ) of vector-axial interaction (hadron, V-A). 相似文献
20.
K. Moriyasu T. Burnett D. Holmgren H.J. Lubatti D. Rees G. Swider B. Yuldashiev K. Dziunikowska A. Eskreys K. Eskreys A. Gula D. Kisielewska H. Rudnicka P. Stopa W. Ko R.L. Lander J.S. Pearson D. Pellett A. Zieminski 《Nuclear Physics B》1978,137(4):377-389
Double-scattering effects are studied in π?d interactions at 360 GeV/c. The partial cross sections are presented. The double-scattering probability per πd collision is found to be . We have extracted the partial cross section XN of the double-scattering plus interference contributions, and find that XN obeys KNO scaling. The data are compared with various theoretical predictions. 相似文献