119452619
Charged-particle rapidity density in Au+Au collisions in a quark combination model
Rapidity/pseudorapidity densities for charged particles and their centrality, rapidity, and energy dependence in Au+Au collisions at the Relativistic Heavy Ion Collider are studied in a quark combination model. Using a Gaussian-type rapidity distribution for constituent quarks as a result of Landau hydrodynamic evolution, the data at {radical}(s{sub NN})=130,200 GeV at various centralities in full pseudorapidity range are well described, and the charged-particle multiplicities are reproduced as functions of the number of participants. The energy dependence of the shape of the dN{sub ch}/d{eta} distribution is also described at various collision energies {radical}(s{sub NN})=200,130,62.4 GeV in central collisions with same value of parameters except 19.6 GeV. The calculated rapidity distributions and yields for the charged pions and kaons in central Au+Au collisions at {radical}(s{sub NN})=200 GeV are compared with experimental data of the BRAHMS Collaboration.
120824945
The nearest correlation in rapidity and the multiplicity distribution in e+e- annihilation
The authors discuss the combination rule of quarks controlled by the nearest correlation in rapidity. The average yields of mesons, baryons and the multiplicity spectra produced by stochastic accumulation of N pairs of quarks are given. Using the relation between the average yields of quark pairs and energy, which is in fact universal, they calculate the observed yields of meson, baryon and the multiplicity distribution in e+e- annihilation. Comparisons are made of their prediction with the experimental data and the negative binomial distribution.
123382323
Inclusive production of meson resonances and the sea-quark distributions in the proton
We have extended the application of the recombination model to the production of meson resonances. The x distributions of mesons produced in the pp reactions, including resonances, were found to display certain simple relations, which are independent of specific assumptions about the sea-quark distributions. These predictions can be used both to examine the model and to differentiate between the distributions of strange and nonstrange seaquarks. In the smaller-x region the shapes of meson inclusive distributions sensitivity depend on the sea-quark distribution. Because in the pseudoscalar-meson case, that is just in the same region where contamination from the resonance decay is serious, we use resonance production to determine directly the sea-quark distributions. If we assume that the sea-quark distributions of all three flavors have the same x dependence, with only the normalization of the strange-quark distribution being suppressed, good agreement with the available data can be achieved. And, with the distribution of seaquarks known, the shape of the inclusive distribution for meson production can then be determined without any further adjustable parameters.
119221593
THE INFLUENCE OF NET QUARKS ON YIELDS AND RAPIDITY SPECTRA OF IDENTIFIED HADRONS
Within a quark combination model, we study systematically the yields and rapidity spectra of various hadrons in central Au + Au collisions at $\sqrt{s_{\rm NN}} = 200\ {\rm GeV}$. We find that considering the difference in rapidity between net quarks and newborn quarks, the data of multiplicities, rapidity distributions for π±, K±, $p(\bar{p})$ and, in particular, the ratios of charged antihadron to hadron as a function of rapidity, can be well described. The effects of net quarks on various hadrons are analyzed, and the rapidity distributions for $K^{0}_{s}$, $\Lambda(\bar{\Lambda})$, $\Sigma^{+}(\bar{\Sigma}{}^{-})$, $\Xi^{-}(\bar{\Xi}^{+})$ and $\Omega^{-}(\bar{\Omega}^{+})$ are predicted. We discuss the rapidity distribution of net baryons, and find that it reflects exactly the energy loss of colliding nuclei.
17880016
COLOR AND KINEMATIC INTERFERENCE INFLUENCE ON THE PROBABILITY OF COLOR SINGLET CHAIN STATES
In popular event generators of high energy reaction, the large Nc, the number of color approximation is implied, which reduces the possible interference effects, and the probability of color singlet chain reaches to about 100%. In $Nc=3$ real world, we show that not only the color interference decreases this probability to 83%, 77%, 72%, $...$, respectively to $n=2$, 3, 4, $...$, {in the process of}$e^+e^-{\longrightarrow}q\bar {q}+ng$ final state, but also the accompanying kinematic interference exists, which decreases this probability to about 67%, 58%, $...$, further. In the meanwhile, we fin d that the kinematic interference makes the probability of color separate singlet states increases synchronously. Combing and analyzing above facts, we infer that the probability of color singlet chain states in high energy ${e^+e^-}{\longrightarrow}{h's}$ reaction would be much smaller than 100%, which is commonly accepted. And the fraction of other color connec tion states, $e.g.$, color separate singlet states should be significant.
46651811
Study of the color string configuration in a multiparton system.
103724302
Study of B0 ---> anti-D(*)0 pi+ pi- decays
126415460
Study of B+ ---> p anti-Lambda gamma, p anti-Lambda pi0 and B0 ---> p anti-Lambda pi-
28141613
Measurement of azimuthal asymmetries in inclusive production of hadron pairs in e(+)e(-) annihilation at Belle.
The Collins effect connects transverse quark spin with a measurable azimuthal dependence in the yield of hadronic fragments around the quark's momentum vector. Using two different reconstruction methods, we find evidence of statistically significant azimuthal asymmetries for charged pion pairs in e(+)e(-) annihilation at a center-of-mass energy of 10.52 GeV, which can be attributed to a transverse polarization of the primordial quarks. The measurement was performed using a sample of 79 x 10(6) hadronic events collected with the Belle detector.
32023501
Search for invisible decay of the Upsilon(1S).
We report results of a search for the invisible decay of the Upsilon(1S) via the Upsilon(3S)-->pi+ pi- Upsilon(1S) transition using a data sample of 2.9 fb-1 at the Upsilon(3S) resonance. The data were collected with the Belle detector at the KEKB asymmetric-energy e+ e- collider. No signal is found, and an upper limit for the branching fraction at the 90% confidence level is determined to be B(Upsilon(1S)-->invisible)<2.5 x 10(-3).
124864860
Improved measurements of anti-B0 ---> D+(sJ) K- decays