共查询到20条相似文献,搜索用时 46 毫秒
1.
Recent data on hadron multiplicities in central Pb+Pb collisions at 158 A GeV/c at mid-rapidity are analyzed within the concept of chemical freeze-out. A non-uniformity of the baryon chemical potential along the beam axis is taken into account. An approximate analytical solution of the hydrodynamic equations for a chemically frozen Boltzmann-like gas is found. The Cauchy conditions for hydrodynamic evolution of the hadron resonance gas are fixed at the thermal freeze-out hypersurface from analysis of one-particle momentum spectra and HBT correlations. The proper time of chemical freeze-out and physical conditions at the hadronization stage, such as energy density and averaged transverse velocity, are found. 相似文献
2.
We perform a systematic analysis of exclusive hadronic channels in e+e− collisions at center-of-mass energies between 2.1 and 2.6 GeV within the statistical hadronization model. Because of the
low multiplicities involved, calculations have been carried out in the full microcanonical ensemble, including conservation
of energy-momentum, angular momentum, parity, isospin, and all relevant charges. We show that the data are in an overall good
agreement with the model for an energy density of about 0.5 GeV/fm3 and an extra-strangeness suppression parameter γ
S
∼0.7, essentially the same values found with fits to inclusive multiplicities at higher energy. 相似文献
3.
We introduce the Transchemistry Model as a dynamical extension of the Algebraic Coalescence Rehadronization (ALCOR) model in describing the hadronization of quark matter which is expected to be produced in relativistic heavy ion collisions. Results are presented for CERN SPS NA49 Pb+Pb experiment calculating hadron multiplicities and momentum spectra. The freeze-out properties of different hadrons are characterized by similar temperature, density and flow profiles in cylindrically symmetric geometry. 相似文献
4.
This paper reviews the experimental and phenomenological aspects of electron-positron annihilation into hadrons at center-of-mass energies above 2 GeV. The behavior of the total cross section for hadron production as a function of energy is described; and the important parameter R - the ratio of this cross section to the muon-pair production cross section - is discussed. Data on charged particle multiplicities, particle production ratios, and single particle inclusive distributions is also summarized. The paper than summarizes our knowledge of the newly discovered ψ particles; and examines the various theories as to their nature and their relation to conventional hadronic physics. 相似文献
5.
We extract the transverse momentum distribution of effective partons using the spectra of Ω, Ξ, Λ and ϕ hadrons measured by the STAR Collaboration from Au + Au collisions at $
\sqrt {s_{NN} }
$
\sqrt {s_{NN} }
= 200 GeV at RHIC. The extracted momentum distribution of strange quarks is flatter than that of up/down quarks consistent
with hydrodynamics expansion in partonic phase prior to hadronization. Consistency in quark ratios derived from various hadron
spectra gives clear evidence for hadron production as suggested by quark coalescence or recombination model. 相似文献
6.
J. Manninen E. L. Bratkovskaya W. Cassing O. Linnyk 《The European Physical Journal C - Particles and Fields》2011,71(4):1615
We study dilepton production in proton–proton, Cu+Cu as well as in Au+Au collisions at the center-of-mass energy \(\sqrt{s} =200\) GeV per participating nucleon pair within an extended statistical hadronization model. In extension to earlier studies we incorporate transport calculations for an estimate of uncorrelated e + e ? -pairs from semileptonic D meson decays. While the invariant mass spectrum of dielectrons is well understood in the p+p collisions, severe discrepancies among different model scenarios based on hadronic degrees of freedom and recent data from the PHENIX Collaboration are found in heavy-ion collisions in the low-mass region from 0.15 to 0.6 GeV as well as in the intermediate mass regime from 1.1 to 3 GeV when employing the standard dilepton sources. We investigate, furthermore, the background from correlated dileptons that are not emitted as a pair from a parent hadron but emerge from semileptonic decays of two correlated daughter hadrons. Our calculations suggest a sizeable contribution of such sources in central heavy-ion collisions in the low-mass region. However, even the upper limits of our calculations are found to be far below the dilepton mass spectra of the PHENIX Collaboration. 相似文献
7.
We study soft hadron production in relativistic heavy-ion collisions in a wide range of reaction energy, 4.8 GeV <
< 200 GeV, and make predictions about yields of particles using the statistical hadronization model. In fits to experimental
data, we obtain both the statistical parameters as well as physical properties of the hadron source. We identify the properties
of the fireball at the critical energy threshold, 6.26 GeV <
< 7.61 GeV, marking for higher energies the hadronization of an entropy-rich phase. In terms of the chemical composition,
one sees a phase which at low energy is chemically under-saturated, and which turns into a chemically over-saturated state
persisting up to the maximum accessible energy. Assuming that there is no change in physical mechanisms in the energy range
15 >
≥200 GeV, we use continuity of particle yields and statistical parameters to predict the hadron production at
= 62.4 GeV, and obtain total yields of hadrons at
= 130 GeV. We consider, in depth, the pattern we uncover within the hadronization condition, and discuss possible mechanisms
associated with the identified rapid change in system properties at
. We propose that the chemically over-saturated 2 + 1 flavor hadron matter system undergoes a 1st-order phase transition. 相似文献
8.
M. V. Tokarev 《Physics of Atomic Nuclei》2011,74(5):799-804
The production of hadrons in heavy-ion collisions at high-p
T
provides an important information on mechanism of particle formation and constituent energy loss in medium. Such information
is needed for search of a Critical Point and signatures of phase transition. Measurements by the STAR Collaboration of charged
hadron production in Au + Au collisions at √s
NN
= 9.2 GeV over a wide transverse momentum p
T
= 0.2−4 GeV/c and at mid-rapidity range are reported. It allows for a first measurement of the spectra for charged hadrons at high p
T
at this energy. The spectra demonstrate the dependence on centrality which enhances with p
T
. The constituent energy loss and its dependence on transverse momentum of particle, and centrality of collisions are estimated
in the z-scaling approach. 相似文献
9.
Adler C Ahammed Z Allgower C Amonett J Anderson BD Anderson M Averichev GS Balewski J Barannikova O Barnby LS Baudot J Bekele S Belaga VV Bellwied R Berger J Bichsel H Billmeier A Bland LC Blyth CO Bonner BE Boucham A Brandin A Bravar A Cadman RV Caines H Calderón de la Barca Sánchez M Cardenas A Carroll J Castillo J Castro M Cebra D Chaloupka P Chattopadhyay S Chen Y Chernenko SP Cherney M Chikanian A Choi B Christie W Coffin JP Cormier TM Cramer JG Crawford HJ Deng WS Derevschikov AA 《Physical review letters》2002,89(20):202301
Inclusive transverse momentum distributions of charged hadrons within 0.2
相似文献
10.
Back BB Baker MD Ballintijn M Barton DS Becker B Betts RR Bickley AA Bindel R Budzanowski A Busza W Carroll A Decowski MP García E Gburek T George N Gulbrandsen K Gushue S Halliwell C Hamblen J Harrington AS Henderson C Hofman DJ Hollis RS Hołyński R Holzman B Iordanova A Johnson E Kane JL Khan N Kulinich P Kuo CM Lee JW Lin WT Manly S Mignerey AC Noell A Nouicer R Olszewski A Pak R Park IC Pernegger H Reed C Remsberg LP Roland C Roland G Sagerer J Sarin P Sawicki P Sedykh I Skulski W Smith CE 《Physical review letters》2003,91(7):072302
We have measured transverse momentum distributions of charged hadrons produced in d+Au collisions at sqrt[s(NN)]=200 GeV. The spectra were obtained for transverse momenta 0.25
相似文献
11.
I. P. Lokhtin A. V. Belyaev A. M. Snigirev 《The European Physical Journal C - Particles and Fields》2011,71(5):1650
The first LHC data on high transverse momentum hadron and dijet spectra in PbPb collisions at center-of-mass energy 2.76 TeV
per nucleon pair are analyzed in the frameworks of PYQUEN jet quenching model. The presented studies for the nuclear modification
factor of high-p
T
hadrons and the imbalance in dijet transverse energy support the supposition that the intensive wide-angular (“out-of-cone”)
medium-induced partonic energy loss is seen in central PbPb collisions at the LHC. 相似文献
12.
Produced partons have a large local relative orbital angular momentum along the direction opposite to the reaction plane in the early stage of noncentral heavy-ion collisions. Parton scattering is shown to polarize quarks along the same direction due to spin-orbital coupling. Such global quark polarization will lead to many observable consequences, such as left-right asymmetry of hadron spectra and global transverse polarization of thermal photons, dileptons, and hadrons. Hadrons from the decay of polarized resonances will have an azimuthal asymmetry similar to the elliptic flow. Global hyperon polarization is studied within different hadronization scenarios and can be easily tested. 相似文献
13.
Acosta D Affolder T Albrow MG Ambrose D Amidei D Anikeev K Antos J Apollinari G Arisawa T Artikov A Ashmanskas W Azfar F Azzi-Bacchetta P Bacchetta N Bachacou H Badgett W Barbaro-Galtieri A Barnes VE Barnett BA Baroiant S Barone M Bauer G Bedeschi F Behari S Belforte S Bell WH Bellettini G Bellinger J Benjamin D Beretvas A Bhatti A Binkley M Bisello D Bishai M Blair RE Blocker C Bloom K Blumenfeld B Bocci A Bodek A Bolla G Bolshov A Bortoletto D Boudreau J Bromberg C Brubaker E Budagov J 《Physical review letters》2005,94(17):171802
We report the first largely model independent measurement of charged particle multiplicities in quark and gluon jets, Nq and Ng, produced at the Fermilab Tevatron in pp collisions with a center-of-mass energy of 1.8 TeV and recorded by the Collider Detector at Fermilab. The measurements are made for jets with average energies of 41 and 53 GeV by counting charged particle tracks in cones with opening angles of theta(c) = 0.28, 0.36, and 0.47 rad around the jet axis. The corresponding jet hardness Q = Ejet theta c varies in the range from 12 to 25 GeV. At Q = 19.2 GeV, the ratio of multiplicities r = Ng/Nq is found to be 1.64+/-0.17, where statistical and systematic uncertainties are added in quadrature. The results are in agreement with resummed perturbative QCD calculations. 相似文献
14.
Adler SS Afanasiev S Aidala C Ajitanand NN Akiba Y Alexander J Amirikas R Aphecetche L Aronson SH Averbeck R Awes TC Azmoun R Babintsev V Baldisseri A Barish KN Barnes PD Bassalleck B Bathe S Batsouli S Baublis V Bauer F Bazilevsky A Belikov S Berdnikov Y Bhagavatula S Boissevain JG Borel H Borenstein S Brooks ML Brown DS Bruner N Bucher D Buesching H Bumazhnov V Bunce G Burward-Hoy JM Butsyk S Camard X Chai JS Chand P Chang WC Chernichenko S Chi CY Chiba J Chiu M Choi IJ Choi J Choudhury RK 《Physical review letters》2005,95(20):202001
15.
A new approach to the analysis of soft and semihard hadron processes is suggested. In the framework of the Quark-Gluon String Model, the interaction of quarks from colliding hadrons is calculated as the exchange by nonperturbative gluons, for which the cut-off parameter in the gluonic propagator is included. This modification has allowed us to analyse the inclusive hadron spectra in hadron collisions at transverse momenta up to 3–4 GeV/c. 相似文献
16.
We describe high energy nuclear collisions by a superposition of isotropically decaying thermal sources (“fireballs”) of freeze-out temperature T = 0.15 GeV. The longitudinal fireball superposition is taken as boost-invariant, in a rapidity range determined by the average energy loss of nucleons in p?p collisions. The transverse fireball motion is assumed to be due to random walk initial state collisions; it is determined by p?A data and then extrapolated to central A?B interactions. We thus obtain parameter-free predictions for the rapidity and transverse momentum spectra of hadrons produced in high energy nucleus-nucleus collisions. The results account fully for the observed broadening of transverse momentum distributions, so that single-particle spectra require neither collective flow nor temperature increase. 相似文献
17.
Back BB Baker MD Ballintijn M Barton DS Betts RR Bickley AA Bindel R Busza W Carroll A Chai Z Decowski MP García E Gburek T George N Gulbrandsen K Halliwell C Hamblen J Hauer M Henderson C Hofman DJ Hollis RS Hołyński R Holzman B Iordanova A Johnson E Kane JL Khan N Kulinich P Kuo CM Lin WT Manly S Mignerey AC Nouicer R Olszewski A Pak R Reed C Roland C Roland G Sagerer J Seals H Sedykh I Smith CE Stankiewicz MA Steinberg P Stephans GS Sukhanov A Tonjes MB Trzupek A Vale C van Nieuwenhuizen GJ 《Physical review letters》2005,94(8):082304
We have measured transverse momentum distributions of charged hadrons produced in Au+Au collisions at sqrt[s(NN)]=62.4 GeV. The spectra are presented for transverse momenta 0.25
相似文献
18.
We discuss different sources of hadron correlations in relativistic heavy ion collisions. We show that correlations among partons in a quasithermal medium can lead to the correlated emission of hadrons by quark recombination and argue that this mechanism offers a plausible explanation for the dihadron correlations in the few GeV/c momentum range observed in Au+Au collisions at the BNL Relativistic Heavy Ion Collider. 相似文献
19.
The attenuation of hadrons produced in leptonnucleus collisions is calculated in the string model of hadronization. The end points of the coloured string are assumed to interact in nuclear matter via colour exchange without changing their energy and momentum. It is shown that the interactions of the leading quark and of those produced in the colour field cause different rearrangement of the string and contribute differently to the particle production. Comparison to the data shows reasonable agreement in the region of higher energies but does not improve the previous fits at 10 GeV.Work supported in part by the KBN grants no. 2 0092 91 01 and no. 2 0054 91 01 相似文献
20.
Data on the mean multiplicity of strange hadrons produced in minimum bias proton-proton and central nucleus-nucleus collisions at momenta between 2.8 and 400 GeV/c per nucleon have been compiled. The multiplicities for nucleon-nucleon interactions were constructed. The ratios of strange particle multiplicity to participant nucleon as well as to pion multiplicity are larger for central nucleus-nucleus collisions than for nucleon-nucleon interactions at all studied energies. The data at AGS energies suggest that the latter ratio saturates with increasing masses of the colliding nuclei. The strangeness to pion multiplicity ratio observed in nucleon-nucleon interactions increases with collision energy in the whole energy range studied. A qualitatively different behaviour is observed for central nucleus-nucleus collisions: the ratio rapidly increases when going from Dubna to AGS energies and changes little between AGS and SPS energies. This change in the behaviour can be related to the increase in the entropy production observed in central nucleus-nucleus collisions at the same energy range. The results are interpreted within a statistical approach. They are consistent with the hypothesis that the Quark Gluon Plasma is created at SPS energies, the critical collision energy being between AGS and SPS energies. 相似文献