共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
Z. Rudy W. Cassing L. Jarczyk B. Kamys P. Kulessa 《The European Physical Journal A - Hadrons and Nuclei》2002,15(3):303-314
The production of K+-mesons in proton-nucleus collisions from 1.0 to 2.5GeV is analyzed with respect to one-step nucleon-nucleon ( NN → NYK
+) and two-step Δ-nucleon ( ΔN → K
+
YN) or pion-nucleon ( πN → K
+
Y) production channels on the basis of a coupled-channel transport approach (CBUU) including the kaon final-state interactions.
The influence of momentum-dependent potentials for the nucleon, hyperon and kaon in the final state are studied as well as
the importance of K+ elastic rescattering in the target nucleus. The transport calculations are compared to the experimental K+ spectra taken at LBL Berkeley, SATURNE, CELSIUS, GSI and COSY-Jülich. It is found that the momentum-dependent baryon potentials
affect the excitation function of the K+ cross-section; at low bombarding energies of ∼ 1.0GeV the attractive baryon potentials in the final state lead to a relative
enhancement of the kaon yield, whereas the net repulsive potential at bombarding energies ∼ 2GeV causes a decrease of the
K+ cross-section. Furthermore, it is pointed out that especially the K+ spectra at low momenta (or kinetic energy T
K) allow to determine the in-medium K+ potential almost model independently due to a relative shift of the K+ spectra in kinetic energy that arises from the acceleration of the kaons when propagating out of the nuclear medium to free
space, i.e. converting the potential energy to the kinetic energy of the free kaon.
Received: 28 January 2002 / Accepted: 3 June 2002 / Published online: 19 November 2002
RID="a"
ID="a"e-mail: Wolfgang.Cassing@theo.physik.uni-giessen.de
Communicated by P. Schuck 相似文献
3.
Haibin Zhang 《The European Physical Journal C - Particles and Fields》2007,49(1):355-358
We report on the measurements of D0 meson production via direct reconstruction through the hadronic decay channel D0→Kπ in minimum bias d+Au and Au+Au collisions at with pT up to ∼3 GeV/c. We derive the charm production total cross-section per nucleon–nucleon collision from a combination of three
measurements: the D0 meson spectra, the non-photonic electron spectra from charm semi-leptonic decays obtained in p+p, d+Au, and Au+Au collisions,
and the charm-decayed single muon (prompt muon) spectra at low pT in Au+Au collisions. The cross-section is found to follow binary scaling, which is a signature of charm production exclusively
at the initial impact. The implications of charm quark energy-loss and thermalization in the strongly interacting matter are
discussed.
PACS 25.75.Dw; 13.20.Fc; 13.25.Ft; 24.85.+p 相似文献
4.
A. Sibirtsev J. Haidenbauer H. -W. Hammer U. -G. Meißner 《The European Physical Journal A - Hadrons and Nuclei》2007,32(2):229-241
We utilize existing inclusive data on K+-meson momentum spectra of the reaction pp→K
+
X at T
p = 2.3-2.85GeV to deduce total cross-sections for pp→K
+
Σ
+
n. The method used to extract those cross-sections is explained and discussed in detail. Our result for T
p = 2.85GeV is consistent with the data point from a direct measurement at the same beam energy. The cross-section obtained
for T
p = 2.3GeV is with 13.7±2.3μb considerably smaller than the value found in a recent experiment by the COSY-11 Collaboration
at a somewhat lower beam energy, indicating that the pp→K
+
Σ
+
n reaction cross-section could exhibit a rather unusual energy dependence. 相似文献
5.
H. -W. Siebert 《The European physical journal. Special topics》2008,162(1):147-153
The large amount of data on hyperon polarizations in inclusive production by hadrons at high energies has recently been extended
to Λ and Ξ
− production by Σ
− beams. The sign of the Ξ
− polarization is negative and the same as in Λ and Ξ
− production by protons. The sign of the Λ polarization, however, is positive, in contrast to the negative sign expected by analogy to the proton beam data for Λ and Ξ
− polarization. Theoretical expectations, for instance from a recombination model, also favoured negative polarization of Λ produced by Σ
−. Moreover, while the Λ polarization increases with p
t
at values below ≈1 GeV/c as observed for other hyperon polarizations, it vanishes above p
t
≈ 1.2 GeV/c. Such a breakdown at large pt has not been observed in any other beam/hyperon combination. 相似文献
6.
H. van Pee O. Bartholomy V. Crede A. V. Anisovich G. Anton R. Bantes Yu. Beloglazov R. Bogendörfer R. Castelijns A. Ehmanns J. Ernst I. Fabry H. Flemming A. Fösel M. Fuchs Ch. Funke R. Gothe A. Gridnev E. Gutz St. Höffgen I. Horn J. Hößl J. Junkersfeld H. Kalinowsky F. Klein E. Klempt H. Koch M. Konrad B. Kopf B. Krusche J. Langheinrich H. Löhner I. Lopatin J. Lotz H. Matthäy D. Menze J. Messchendorp V. A. Nikonov D. Novinski M. Ostrick A. Radkov A. V. Sarantsev S. Schadmand C. Schmidt H. Schmieden B. Schoch G. Suft V. Sumachev T. Szczepanek U. Thoma D. Walther Ch. Weinheimer 《The European Physical Journal A - Hadrons and Nuclei》2007,31(1):61-77
Photoproduction of π0-mesons was studied with the Crystal-Barrel detector at ELSA for incident energies from 300MeV to 3GeV. Differential cross-sections
dσ/dΩ, dσ/dt, and the total cross-section are presented. For E
γ < 3GeV, the angular distributions agree well with the SAID parametrization. At photon energies above 1.5GeV, a strong forward
peaking indicates t-channel exchange to be the dominant process. The rapid variations of the cross-section with energy and angle indicate production
of resonances. An interpretation of the data within the Bonn-Gatchina partial-wave analysis is briefly discussed. 相似文献
7.
We extract the neutron charge form factor G
n
E(Q
2) from the charge form factor of deuteron G
d
C(Q
2) obtained from T
20(Q
2) data at 0≤Q
2≤ 1.717 (GeV/c)2. The extraction is based on the relativistic impulse approximation in the instant form of the relativistic Hamiltonian dynamics.
Our results (12 new points) are compatible with existing values of the neutron charge form factor of other authors. We propose
a fit for the whole set (36 points) taking into account the data for the slope of the form factor at Q
2 = 0.
Received: 26 July 2002 / Accepted: 18 September 2002 / Published online: 4 February 2003
RID="a"
ID="a"e-mail: krutov@ssu.samara.ru
RID="b"
ID="b"e-mail: troitsky@theory.sinp.msu.ru
Communicated by V.V. Anisovich 相似文献
8.
《The European Physical Journal A - Hadrons and Nuclei》2008,38(2):195-207
The photoproduction of η -mesons off 12C , 40Ca , 93Nb , and
nat
Pb nuclei has been measured with a tagged photon beam with energies between 0.6 and 2.2GeV. The experiment was performed at
the Bonn ELSA accelerator with the combined setup of the Crystal Barrel and TAPS calorimeters. It aimed at the in-medium properties
of the S
11(1535) nucleon resonance and the study of the absorption properties of nuclear matter for η -mesons. Careful consideration
was given to contributions from ηπ final states and secondary production mechanisms of η -mesons, e.g. from inelastic πN reactions of intermediate pions. The analysis of the mass number scaling shows that the nuclear absorption cross-section
for η -mesons is constant over a wide range of the η momentum. The comparison of the excitation functions to data off the
deuteron and to calculations in the framework of a BUU model show no unexplained in-medium modifications of the S
11(1535) . 相似文献
9.
T. J. Humanic 《Physics of Particles and Nuclei Letters》2011,8(9):903-906
A kinematic model based on the superposition of p + p collisions, relativistic geometry and final-state hadronic rescattering is used to predict two-boson HBT parameters in √s
NN
= 2.76 TeV Pb + Pb collisions. A short proper time for hadronization is assumed. Previous calculations using this model which
were performed for √s
NN
= 200 GeV Au + Au collisions were shown to describe reasonably well the trends of two-pion HBT in experiments carried out
at that energy, giving the present predictions for Pb + Pb at higher energy some degree of credibility. 相似文献
10.
R. Brandt V. A. Ditlov K. K. Dwivedi W. Ensinger E. Ganssauge Guo Shi-Lun M. Haiduc S. R. Hashemi-Nezhad H. A. Khan M. I. Krivopustov R. Odoj E. A. Pozharova V. A. Smirnitzki A. N. Sosnin W. Westmeier M. Zamani-Valasiadou 《Physics of Particles and Nuclei》2008,39(2):259-285
Interactions of relativistic heavy ions with total energies above 30 GeV in thick Cu and Pb targets (≥ 2 cm) have been studied
with various techniques. Radiochemical irradiation experiments using thick Cu targets, both in a compact form or as diluted
“2π-Cu targets” have been carried out with several relativistic heavy ions, such as 44 GeV 12C (JINR, Dubna, Russia) and 72 GeV 40Ar (LBL, Berkeley, USA). Neutron measuring experiments using thick targets irradiated with various relativistic heavy ions
up to 44 GeV 12C have been performed at the JINR. In addition, the number of “black prongs” in nuclear interactions (due to protons with
energies less than 30 MeV and emitted from the target-like interaction partner at rest) produced with 72 GeV 22Ne ions in nuclear emulsion plates has been measured in the first nuclear interaction of the primary 22Ne ion and in the following second nuclear interaction of the secondary heavy (Z > 1) ion. Some essential results have been obtained. (1) Spallation products produced by relativistic secondary fragments
in interactions ([44 GeV 12C or 72 GeV 40Ar] + Cu) within thick copper yield fewer products close to the target and many more products far away from the target as
compared to primary beam interactions. This applies also to secondary particles emitted into large angles (Θ > 10°). (2) The
neutron production of 44 GeV 12C within thick Cu and Pb targets is beyond the estimated yield as based on experiments with 12 GeV 12C. These rather independent experimental results cannot be understood within well-accepted nuclear reaction models. They appear
to present unresolved problems.
The text was submitted by the authors in English. 相似文献
11.
V. Kumar Chitra Bhatia H. Kumawat J. Adam 《The European Physical Journal A - Hadrons and Nuclei》2009,40(2):231-236
Production cross-sections of monitor reaction 27Al(x, y)24Na for proton, neutron and deuteron projectiles have been estimated from the CASCADE code from tens of MeV/n to tens of GeV/n
energy and compared them with the available experimental data. It has also been shown that using the CASCADE code production
cross-section of 27Al(d, y2)24Na reaction can be obtained from the proton and neutron projectiles. Implicitly, this provides an alternative way of knowing
production cross-section of 27Al(n, y
1)24Na reaction which may be used to monitor the neutron flux in a wide range of energy. However, in the paper need of experimental
determination of cross-sections for neutron projectile has been stressed. Similarly, cross-section of other monitor reactions
like 27Al(p, y
′)22Na and 27Al(n, y
′
1)22Na are also calibrated as function of energy up to several GeV. 相似文献
12.
H.W. Dannhausen E.J. Durwen H.M. Fischer M. Leneke W. Niehaus F. Takasaki 《The European Physical Journal A - Hadrons and Nuclei》2001,11(4):441-455
The differential cross-section for the reaction γp↦π +
n was measured using the bremsstrahlung beam of the Bonn 2.5 GeV electron synchrotron. The pions were detected and momentum
analysed in a multichannel magnet spectrometer. Data reduction resulted in 1278 measured cross-sections which are presented
as energy distributions at six laboratory angles between 180° and 95°. The range of laboratory photon energies extended from
0.3 to 2.1 GeV. The statistical accuracy is better than 3 percent, the systematic error is about 5 percent. The data are compared
with other experimental results and predictions of a phenomenological analysis. These cross-sections are the result of a measurement
program which was started in the seventies. Further results will be reported in forthcoming publications.
Received: 2 February 2000 / Accepted: 14 August 2001 相似文献
13.
O. Bartholomy R. Bogendörfer V. Credé I. Fabry A. V. Anisovich G. Anton R. Bantes Y. A. Beloglazov R. Castelijns A. Ehmanns J. Ernst H. Flemming A. Fösel M. Fuchs Ch. Funke R. Gothe A. B. Gridnev E. Gutz S. Höffgen I. Horn J. Hößl J. Junkersfeld H. Kalinowsky F. Klein E. Klempt H. Koch M. Konrad B. Kopf B. Krusche J. Langheinrich H. Löhner I. V. Lopatin J. Lotz H. Matthäy D. Menze J. Messchendorp V. A. Nikonov D. V. Novinski M. Ostrick H. van Pee A. K. Radkov A. V. Sarantsev S. Schadmand C. Schmidt H. Schmieden B. Schoch G. Suft V. V. Sumachev T. Szczepanek U. Thoma D. Walther Ch. Weinheimer 《The European Physical Journal A - Hadrons and Nuclei》2007,33(2):133-146
Photoproduction of η -mesons was studied with the Crystal-Barrel detector at ELSA for photon energies in the range from 0.75
to 3GeV. Total and differential cross-sections are presented. The η mesons are detected in two decay modes, in η → 2γ and
in η → 3π0 → 6γ . The cross-sections vary slowly as functions of energy and η production angle suggesting that only few resonances make
significant contributions to the cross-section. For photon energies above 1.5GeV, the differential cross-sections show a strong
forward peak due to meson exchanges in the t channel. A comparison of the η -photoproduction cross-sections with SAID and MAID as well as with a partial-wave analysis
performed on our data in combination with other data sets shows good agreement. The Bonn-Gatchina partial-wave analysis suggests
that the largest contribution to η photoproduction for energies below 3GeV proceeds via three resonances, the well-known N(1535)S
11 , via N(1720)P
13 , and a newly suggested N(2070)D
15 . 相似文献
14.
A. Lleres O. Bartalini V. Bellini J. P. Bocquet P. Calvat M. Capogni L. Casano M. Castoldi A. D'Angelo J. -P. Didelez R. Di Salvo A. Fantini C. Gaulard G. Gervino F. Ghio B. Girolami A. Giusa M. Guidal E. Hourany V. Kouznetsov R. Kunne A. Lapik P. Levi Sandri D. Moricciani A. N. Mushkarenkov V. Nedorezov L. Nicoletti C. Perrin C. Randieri D. Rebreyend F. Renard N. Rudnev T. Russew G. Russo C. Schaerf M. -L. Sperduto M. -C. Sutera A. Turinge 《The European Physical Journal A - Hadrons and Nuclei》2007,31(1):79-93
Beam asymmetries and hyperon recoil polarizations for the reactions γp → K
+Λ and γp → K
+Σ0 have been measured from the threshold production to 1500MeV with the GRAAL facility located at the ESRF in Grenoble. These
results complement the database for the beam asymmetry, covering for the first time the production threshold region. Recent
theoretical analyses are presented for which the beam asymmetry data bring interesting new information and allow to better
determine some resonance parameters. Most importantly, these results strengthen the need of a new D13 state around 1900MeV. 相似文献
15.
G.I. Lykasov W. Cassing A. Sibirtsev M.V. Rzjanin 《The European Physical Journal A - Hadrons and Nuclei》1999,6(1):71-81
We calculate the elastic and inelastic ωN→ωN, →πN, →ρN, →ρπN, →ππN, →σN reactions within a boson exchange approximation where the ωρπ coupling constant and form factor are fixed by the reaction
πN→ωN in comparison to the experimental data. We find rather large ωN cross sections at low relative momenta of the ω-meson which
leads to a substantial broadening of the ω-meson width in nuclear matter. The implications of the ωN final state interactions are studied for ω production in 12C +12C, 40Ca +40Ca and 58Ni +58Ni reactions at about 2 · A GeV within the HSD transport approach; the drastic changes of the transverse mass spectra relative
to a general m
T-scaling (for π0 and η mesons) might be controlled experimentally by the TAPS Collaboration.
Received: 28 April 1999 / Revised version: 7 June 1999 相似文献
16.
R. Arnaldi K. Banicz K. Borer J. Castor B. Chaurand W. Chen C. Cicalò A. Colla P. Cortese S. Damjanovic A. David A. de Falco A. Devaux L. Ducroux H. En’yo J. Fargeix A. Ferretti M. Floris A. F?rster P. Force N. Guettet A. Guichard H. Gulkanian J. M. Heuser M. Keil L. Kluberg Z. Li C. Louren?o J. Lozano F. Manso P. Martins A. Masoni A. Neves H. Ohnishi C. Oppedisano P. Parracho P. Pillot T. Poghosyan G. Puddu E. Radermacher P. Ramalhete P. Rosinsky E. Scomparin J. Seixas S. Serci R. Shahoyan P. Sonderegger H. J. Specht R. Tieulent G. Usai R. Veenhof H. K. W?hri 《The European Physical Journal C - Particles and Fields》2009,61(4):711-720
The NA60 experiment at the CERN SPS has measured muon pairs with unprecedented precision in 158 A GeV In–In collisions. A strong excess of pairs above the known sources is observed in the whole mass region 0.2<M<2.6 GeV. The mass spectrum for M<1 GeV is consistent with a dominant contribution from π
+
π
−→ρ→μ
+
μ
− annihilation. The associated ρ spectral function shows a strong broadening, but essentially no shift in mass. For M>1 GeV, the excess is found to be prompt, not due to enhanced charm production, with pronounced differences to Drell–Yan pairs.
The slope parameter T
eff associated with the transverse momentum spectra rises with mass up to the ρ, followed by a sudden decline above. The rise for M<1 GeV is consistent with radial flow of a hadronic emission source. The seeming absence of significant flow for M>1 GeV and its relation to parton–hadron duality is discussed in detail, suggesting a dominantly partonic emission source
in this region. A comparison of the data to the present status of theoretical modeling is also contained. The accumulated
empirical evidence, including also a Planck-like shape of the mass spectra at low p
T
and the lack of polarization, is consistent with a global interpretation of the excess dimuons as thermal radiation. We conclude
with first results on ω in-medium effects. 相似文献
17.
《The European Physical Journal A - Hadrons and Nuclei》2008,35(3):333-342
The exclusive reactions γp → K
*0Σ+(1189) and γp → K
0π0Σ+(1189) , leading to the p 4π0 final state, have been measured with a tagged photon beam for incident energies from threshold up to 2.5GeV. The experiment
has been performed at the tagged photon facility of the ELSA accelerator (Bonn). The Crystal Barrel and TAPS detectors were
combined to a photon detector system of almost 4π geometrical acceptance. Differential and total cross-sections are reported.
At energies close to the threshold, a flat angular distribution has been observed for the reaction γp → K
0π0Σ+ suggesting dominant s -channel production. Σ*(1385) and higher-lying hyperon states have been observed. An enhancement in the forward direction in the angular distributions
of the reaction γp → K
*0Σ+ indicates a t -channel exchange contribution to the reaction mechanism. The experimental data are in reasonable agreement with recent theoretical
predictions. 相似文献
18.
J. Brachmann A. Dumitru H. Stöcker W. Greiner 《The European Physical Journal A - Hadrons and Nuclei》2000,8(4):549-552
We investigate the excitation function of quark-gluon plasma formation and of directed in-plane flow of nucleons in the energy
range of the BNL-AGS and for the E
kin
Lab = 40A GeV Pb + Pb collisions performed recently at the CERN-SPS. We employ the three-fluid model with dynamical unification of
kinetically equilibrated fluid elements. Within our model with first-order phase transition at high density, droplets of QGP
coexisting with hadronic matter are produced already at BNL-AGS energies, E
kin
Lab≃ 10A GeV. A substantial decrease of the isentropic velocity of sound, however, requires higher energies, E
kin
Lab≃ 40A GeV. We show the effect on the flow of nucleons in the reaction plane. According to our model calculations, kinematic requirements
and EoS effects work hand-in-hand at E
kin
Lab = 40A GeV to allow the observation of the dropping velocity of sound via an increase of the directed flow around midrapidity as compared to top BNL-AGS energy.
Received: 7 May 2000 / Accepted: 2 August 2000 相似文献
19.
Y.C. Shin M.K. Cheoun K.S. Kim T.K. Choi 《The European Physical Journal A - Hadrons and Nuclei》2002,14(1):87-93
A role of the axial-vector mesons, such as K1 and a1, on the emitted-photon spectrum in hot hadronic matter is studied through the channels πρ→a
1→πγ and Kρ→K
1→Kγ. Both channels could be dominant over the region lower than E
γ∼ 0.5 GeV, while the role of the K1 meson is diminished in the higher E
γ region. This study is carried out with an SU
L(3) ⊗SU
R(3) effective chiral Lagrangian which includes vector and axial-vector mesons systematically and explains well their hadronic
and radiative decays simultaneously.
Received: 8 August 2001 / Accepted: 4 February 2002 相似文献
20.
A. Sibirtsev J. Haidenbauer H. -W. Hammer U. -G. Meißner 《The European Physical Journal A - Hadrons and Nuclei》2006,29(3):363-367
We show that the recently measured asymmetry in helicity-angle spectra of the Λ-hyperons, produced in the reaction pp → K
+Λp reaction, and the energy dependence of the total pp → K
+Λp cross-section can be explained consistently by the same Λp final-state interaction. Assuming that there is no final-state interaction in the Σ0
p channel, as suggested by the available data for the reaction pp → K
+Σ0
p, we can also reproduce the energy dependence of the Λ/Σ0 production ratio and, in particular, the rather large ratio observed near the reaction thresholds. The nominal ratio of the
Λ and Σ0 production amplitudes squared, i.e. when disregarding the final-state interaction, turns out to be about 3, which is in line with hyperon production data from
proton and nuclear targets available at high energies. 相似文献