共查询到20条相似文献,搜索用时 31 毫秒
1.
The inclusive production of π+ for 0.4≤pT<1.0 GeV/c in pion-nucleus and proton-nucleus collisions at 4.3 GeV/c was measured. A strong A-dependence of the cross sections at high pT is observed to be persistent in the low energy region. The ratio of the cross sections for proton-nucleus and pion-nucleus collisions is also observed to be compatible with the quark-parton picture, for pT>0.6 GeV/c. 相似文献
2.
J.J. Dugne 《Physics letters. A》1976,56(1):27-28
A new method is described to obtain analytically approximate screened cross sections of atomic-field pair production. The Thomas-Fermi-Csavinszky potential model is expanded at the first order and put in the place of the point Coulomb potential in the Dirac equation. That method can be very useful to calculate approximate screened cross sections for the intermediate photon energy range (5moc2 to about 50moc2) where numerically exact screened cross sections are needing a prohibitive computer time and when the form factor approach based on Born approximation is not always valid. 相似文献
3.
We investigate the feasibility of observing ηc by its OZI-rule-forbidden baryon-antibaryon pair decay in the coherent production (Primakoff effect) of ηc. The cross sections are estimated as a function of photon energy, and the CM angular distribution is calculated. 相似文献
4.
The production of electron pairs by negative and positive electrons in the energy region 0.65 – 5.8 GeV has been investigated in the DESY 81-cm hydrogen bubble chamber. The effective cross section σ = 0.62 ± 0.04 mb averaged over the energy spectrum of incident electrons is found to be in good agreement with the predictions of quantum electrodynamics. The energy distribution of created pairs as well as the dependence of the total cross section on energy are best represented by the expression of Murota, Ueda and Tanaka with the constant c = 0.66 ± 0.170.24 and by Bhabhá's formula with the constants c1 = 1 and c2 = 2.8 ± 0.70.9. The contribution of the interference term between space-like and time-like Feynman diagrams to the cross section is estimated to be less than about 10% and to fall off with an increase of the incident energy. 相似文献
5.
It is shown that charm photoproduction can be consistently described within an asymptotically free field theory. Quantum chromodynamics is used to derive sum rules for the total cross section σcγ which includes both production of mesons with hidden charm (J/ψ, ψ′ and so on) and of charmed particles (pairs , and so on). An estimate of σcγ as a function of energy is given and fast growth is discovered up to energies ~ 1000 GeV. In this energy range σcγ turns out to be equal to several μb. It is argued that measurements of charm photoproduction would give the most direct information on the gluon distribution within a nucleon. All the results are generalized to production of heavier particles containing new quarks. In particular, a simple rescaling law is derived connecting the cross sections for charm and beauty. 相似文献
6.
D. Drijard H.G. Fischer W. Geist P.G. Innocenti V. Korbel A. Minten A. Norton S. Stein O. Ullaland H.D. Wahl P. Burlaud G. Fontaine P. Frenkiel C. Ghesquière G. Sajot P. Hanke W. Hofmann M. Szeptycka 《Physics letters. [Part B]》1979,85(4):452-457
The production of a Λ+c charmed baryon has been observed in pp collisions at the CERN ISR. A sharp peak at 2.26 GeV/c2 was found in the decay mode Λ+c → p in events triggered with a forward K? meson. Also the decay mode Λ+c → K? Δ++ seems to be present. The estimation of the total cross section for Λ+c production is given. However, the resulting value depends on the assumed form of the differential cross section. In addition, Λ+c production in events triggered by the presence of a direct electron is discussed. 相似文献
7.
《Physics letters. [Part B]》1988,215(2):417-420
Using the double-Regge formalism and a supercritical pomeron with αP(0)=1+Δ, we analyse the energy dependence of inclusive cross sections for negatively charged particles (c−) and Ks0 at CM rapidity y=0 in the CERN PS-Sp̄pS collider energy range. The values of Δ(c−)=0.170±0.008 and Δ(Ks0)=0.167±0.024 are found to be very close to each other and compatible with estimates of Δ derived from the total cross sections. 相似文献
8.
F. Stoffel G. Ambrosini G. Appelquist R. Arsenescu C. Baglin J. Beringer C. Bohm K. Borer A. Bussière F. Dittus K. Elsener D. Frei Ph. Gorodetzky J. P. Guillaud P. Hess E. Hugentobler S. Kabana R. Klingenberg T. Lindén K. D. Lohmann R. Mommsen U. Moser T. Pal K. Pretzl J. Schacher B. Selldén F. Stoffel J. Tuominiemi M. Weber Q. P. Zhang 《Acta Physica Hungarica A》1996,4(1-4):429-434
We searched for long-lived strange quark matter particles, so-calledstrangelets, and studied particle and antiparticle production in Pb+Pb collisions at 158 GeV/c per nucleon at zero degree production angle. We give upper limits for the production of strangelets covering a mass to charge ratio up to 120 GeV/c 2 and lifetimest lab>1.2 μs and plot invariant differential production cross sections as a function of rapidity for a variety of particles. 相似文献
9.
P.V. Chliapnikov L.N. Gerdyukov P.A. Gorbunov S.V. Klimenko B.A. Manyukov V.N. Ryadovikov O.G. Tchikilev V.A. Uvarov C. Dujardin F. Grard J. Laurent R. Windmolders M. Csejthey-Barth E. De Wolf F. Verbeure M. Loret L. Mosca J. Laberrigue 《Nuclear Physics B》1978,133(1):93-107
The production of neutral kaons in the reaction K+p → Kn + X is studied at the incident momentum of 32 GeV/c. Inclusive cross sections and single-particle distributions are presented and compared with the data at lower energies. The total inclusive cross section amounts to 7.9 ± 0.3 mb at 32 GeV/c and is significantly higher than at lower energies due to the rapid rise of multikaon production. The fraction of Kn's coming from the decay of the K1 resonances stays roughly constant with energy between 8.2 and 32 GeV/c. In the central and beam fragmentation regions the single-particle distributions reveal no energy dependence between the 16 and 32 GeV/c data in contrast with the behaviour at lower energies, while in the proton fragmentation region the data are compatible with the trend observed at lower energies and with theoretical expectations. 相似文献
10.
Yan-Jun Sun Xing-Gang Wu Fen Zuo Tao Huang 《The European Physical Journal C - Particles and Fields》2010,67(1-2):117-123
We calculate the cross section of the exclusive process e ++e ?→J/ψ+η c at the leading order approximation within the QCD light-cone sum rules approach. It is found that the form factor F VP(V=J/ψ,P=η c ) depends mainly on the behavior of the twist-2 distribution amplitude of the η c meson at the scale of this process. Thus in order to obtain a reliable estimation of the cross section, it is important to have a realistic distribution amplitude of the η c meson and to deal with the evolution of the distribution amplitude to the effective energy scale of the process. Our results show that one can obtain a compatible prediction with the Belle and BaBar experimental data. 相似文献
11.
F. Halzen A. D. Martin D. M. Scott 《Zeitschrift fur Physik C Particles and Fields》1982,13(4):291-294
We calculate the lepton spectrum inpp collisions from the production and semileptonic decay ofΛ c andΛ b , and find limits on their production cross sections. Total cross sections in excess of 1 mb forΛ c and 2 1/2μb forΛ b violate the experimental fact that (μ/π)?10?4. Abundant production ofΛ c has led to speculations on the existence of a large intrinsic charm sea inside the proton. We discuss alternative ways of probing such a structure inside the proton: jets opposite highp T direct photons and central production of ψ. 相似文献
12.
K. Abe R.C. Fernow T.A. Mulera K.M. Terwilliger W. De Boer A.D. Krisch H.E. Miettinen J.R. OFallon L.G. Ratner 《Physics letters. [Part B]》1976,63(2):239-244
The elastic cross section for proton proton scattering at 11.75 GeV/c was measured at the Argonne ZGS using a 50% polarized target. In the range p⊥2=0.6 → 2.2 (GeV/c)2 we obtained precise measurements of for the ? ?, and ? initial spin states perpendicular to the scattering plane. We confirmed that the asymmetry parameter, A, decreases with energy in the diffraction peak, but is approximately energy-independent at large p⊥2. We found that the spin correlation parameter cnn acquires rather dramatic structure, and at large p⊥2 seems to grow with energy. 相似文献
13.
T. Aziz R.R. Daniel S.N. Ganguli A. Gurtu P.K. Malhotra M.M. Aggarwal S.B. Beri V.S. Bhatia I.S. Mittra Gurmukh Singh N.S. Arya D.P. Goyal A. Mozumder P.K. Sengupta S. Singh S. Kumar G.L. Kaul L.K. Mangotra G. Singh 《Nuclear Physics B》1982,199(3):424-440
5032 proton-emulsion interactions at 400 GeV/c momentum have been carefully scrutinized for production and decay of charged charm particles. In order to detect these decays, shower tracks from 3056 stars have been followed to a maximum length of 1 mm and those from 1976 stars up to 2 mm. A total of 23 three-prong charm-like candidates have been recorded in the forward cone. The background due to γ-overlap on a shower track, trident/pseudo-trident production and secondary interactions is estimated to be 15. Attributing the signal of 8 events to Λc+ and assuming the branching ratio of Λc+ → 3 prong to be 0.6 and τΛc to be 10?13 sec we obtain the production cross section to be 106±39μb/nucleon. Out of these 8 events one example of semileptonic decay of Λc+ is seen. 相似文献
14.
F. Ceradini M. Conversi S. DAngelo L. Paoluzi R. Santonico R. Visentin 《Physics letters. [Part B]》1973,47(1):80-84
New results on the multihadron production by electron and positron beams colliding with a total energy of up to 3 GeV are reported. Disregarding possible kaon final states, the ratio σmh/σμμ of the total multihadron cross-section to the point-like cross section for process e+e?→μ+μ? has an average value of 1.58 ± 0.25 in the energy interval 2.6–3.0 GeV. The average charged multiplicity over this energy range is 〈nc〉 = 2.9 ± 0.3. 相似文献
15.
S. Sakai 《Physics letters. [Part B]》1974,48(5):427-430
The origin of the rise of p-p total cross section (σt(pp)) is investigated by making use of the inclusive sum rule. The contribution to the rise of σt(pp) from the development of sharp peak near the kinematical boundary in the process p+p→p+ “anything” is almost completely canceled out by the decrease of the cross section in other x-region between s=45 (GeV/c)2 and s=2820 (GeV/c)2. Then the net contribution to the rise of σt(pp) from the process p+p→p+ “anything” is very likely to be zero. The true origin of the rise of σt(pp) is found to be the increase of inclusive cross sections at x ? 0 between PS and ISR energies. The contribution from the process p+p→π+ “anything” at x ? 0 to the rise of σt(pp) is estimated to be 3.2 mb, that from the process p+p→K + “anything”, 0.71 mb and that from the process p+p→ “anything”, 0.62 mb. According to our conclusion we expect that all total cross sections will rise with energy at high energy. 相似文献
16.
T. Åkesson M.G. Albrow S. Almehed O. Benary H. Bøggild O. Botner H. Brody V. Burkert A. Di Ciaccio D. Cockerill S. Dagan E. Dahl-Jensen I. Dahl-Jensen G. Damgaard W.M. Evans C.W. Fabjan P. Frandsen C. Woody 《Nuclear Physics B》1982,209(2):309-320
The production of charged hadrons with high pT in αα collisions at √s=126 GeV and pp collisions at √s=31 and 63 GeV is compared, and the structure of the events associated with the high-pT particles is studied. The probability of finding associated particles close to the trigger particle increases strongly between √s=31 and 63 GeV for pp collisions. For pT>2.5GeV/c the αα/pp cross section ratio at the same energy per nucleon is measured to be 18.7 ± 2.0, to be compared with A2 = 16, and a higher associated multiplicity is observed for αα. 相似文献
17.
《Physics letters. [Part B]》1988,209(1):127-134
Two-jet mass distributions have been measured as a function of centre-of-mass scattering angle for high-mass jet pairs produced in proton-antiproton collisions at the CERN collider operating at a centre-of-mass energy of 630 GeV. The agreement between QCD expectations and the experimental measurements has been used to place limits on the production cross section of an object X decaying into two jets. In particular we consider the existence of a massive colour octet of vector gauge bosons (axigluons). We exclude axigluons with a width ΛA < 0.4mA and a mass mA in the range 150 < mA < 310 GeV/c2 (95% CL). 相似文献
18.
The partial production cross sections for reaction residues produced by the fusion of 16O with 16O have been measured at Ec.m = 9–30 MeV by detecting the characteristic γ-rays with a Ge(Li) detector. The dominant products are 24Mg and 27A1 corresponding to 2α and αp emission from the compound nucleus, respectively. The total γ-producing cross sections σR were also derived by summing the partial cross sections after correction for the observed (average) γ-ray angular distributions. The trend in the total cross sections is very similar to the trends derived from an optical model or a statistical-evaporation model calculation. The partial production cross sections were compared with other experimental results at 11.9 MeV and 30 MeV and with the results of the statistical-model calculation. It is concluded that the treatment of angular momentum in the calculation is inadequate for describing the partial cross sections. Structure in the partial and total cross section excitation functions is observed with minima occurring at Ec.m. = 27, 24, 20, 17.5, and possibly 15 MeV. Some of this structure is well established by the statistical accuracy of the data and most, but perhaps not all of it, is correlated in the various channels. This structure is compared with that observed in another experiment and some of its implications are discussed. 相似文献
19.
We discuss various mechanisms for inclusive production of cc? bound states in hadron-hadron interactions. We conclude that for ηc, η′c alone, among the bound states, the cross section for production is mainly due to the annihilation of two constituent gluons in a color singlet state. We give detailed results for ηc production cross sections. 相似文献
20.
Tooraj Ghaffary 《International Journal of Theoretical Physics》2018,57(10):3066-3080
In this study by extending the recent suggested mechanisms to hadronization processes, the information loss for QCD matter in hadronic Rindler horizon is found. We notice that for all finite values of quark and gluon energies, all information from all hadronization processes experiences some degree of loss. Then the effect of hedonic Rindler horizon on three jet cross section is explored. It is found that the three jet cross section is rising at ycut =?0.0002 exhibits a turn-over at moderate value of ycut =?0.01 and then rapidly decreases as ycut increases. This model is consistent with OPAL data. Finally, different channels for producing Higgs boson near hadronic Rindler horizon are studied. It is shown that the cross section of Higgs boson produced via gluon fusion and quark interaction near a single Hadronic Rindler Horizon is much larger for higher center of mass energies. This is because an increase in the energy of hadronic Rindler horizon raises the temperature, thus intensifying the thermal radiation of QCD matter. 相似文献