123135520
SIMPLE UNDERSTANDING OF THE ENERGY DEPENDENCE OF THE B/M RATIO AND HADRON MULTIPLICITIES IN e+e− ANNIHILATION
With the help of the color dipole model (CDM) in describing the parton shower process in the perturbative phase in e+e− annihilation, we extend the quark combination model (QCM) of the original form to a more general one in a multiparton system. Then we derive baryon and meson multiplicity formulas for the multiparton system. The new multiplicity formulas are expressed in terms of CDM quantities and . From these formulas, we can readily understand that the energy behavior of the B/M ratio implied by the multiplicity data in e+e− annihilation is the consequence of two competitive processes: one is the dipole splitting which makes B/M decrease and the other is the increase in combination chain length which makes it higher. To check these basic formulas further, we give multiplicities of most ground hadrons at three energies, 10, 30, 90 GeV, by using five main energy-independent parameters, 75% of which agree with data within 1.5 standard error.
118422695
Hadron Yield Correlation in Combination Models in High Energy AA Collisions
We study the hadron yield correlation in the combination models in high energy heavy ion collisions. We derive the relationship between the average yields of different hadrons produced in the combination of a system consisting of equal number of quarks and antiquarks. We present the results for the directly produced hadrons as well as those for the final hadrons including the strong and electromagnetic decay contributions. We also study the net quark influence by considering the case when the number of quarks is larger than that of the antiquarks. We make comparison with the data wherever possible.
197513358
Charm hadron production at RHIC in combination model
We investigate the charm hadron production in relativistic heavy-ion collisions with the quark combination model. The $p_{T}$ dependencies of the charm baryon to meson ratios such as $\frac{\Lambda_{c}+\bar{\Lambda}_{c}}{D^{0}+\bar{D}^{0}}$, $\frac{\Lambda_{c}+\bar{\Lambda}_{c}}{D^{+}+D^{-}}$ and $\frac{\Lambda_{c}+\bar{\Lambda}_{c}}{D_{s}^{+}+D_{s}^{-}}$ in Au+Au collisions at 200 GeV are obtained. The charm baryon enhancement in the intermediate $p_{T}$ range is very prominent, which further, together with the strangeness enhancement, affect the charm hadron ratios and lead to a $\sim17%$ larger charm cross-section given by PHENIX. The dependencies of the charm hadron ratios on energy, centrality, and other parameters are also investigated. Predictions of the charm hadron ratios for the upgrade of RHIC and for LHC are presented.
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.
118877314
A Study of elliptic flows in a quark combination model
We carry out a detail study of elliptic flows in Au-Au collisions at 200 AGeV in a quark combination model. We find that elliptic flow data for a variety of hadrons can be well reproduced except pions if constituent quarks with equal parallel transverse momenta combine into initially produced hadrons. In a combination mechanism where initial hadrons are formed by quarks with unequal parallel transverse momenta, theoretical predictions agree with data for all available hadrons including pions. The mass hierarchy at low transverse momenta in elliptic flows can be understood in the same quark combination mechanism as in the mediate range of transverse momenta.
121208515
Multiplicity distributions in hadron-hadron collisions based on the universality ansatz
Recent experiments on small-${p}_{T}$ hadron production in $\mathrm{pp}$ collisions have shed new light on the apparent violation of the universality ansatz by the fact that the multiplicity dispersion in hadron-hadron collisions is much larger than that in ${e}^{+}{e}^{\ensuremath{-}}$ collisions. We present a model based on the universality ansatz, among other things. This model reproduces qualitatively the hadron multiplicity distributions in $\mathrm{pp}$ collisions over a wide range of energies. Within our framework, this essentially resolves the discrepancy stated above. In our approach the universality ansatz is also found to be applicable to the diffractive component events. This is supported by the inclusive $x$-distribution data having various specified number of prongs in the final states.
200108193
Time-dependent CP asymmetries in b ---> s anti-q q transitions and sin 2 phi(1) in B0 ---> j/psi K0 decays with 386 million B anti-B pairs
27068281
Measurement of the near-threshold e+e- --> D(*)+/-D(*)-/+ cross section using initial-state radiation.
We report a measurement of the exclusive e+e- -->D(*)+/-D*-/+ cross section as a function of center-of-mass energy near the D(*)+/-D*-/+ threshold with initial-state radiation. A partial reconstruction technique is used to increase the efficiency and to suppress background. The analysis is based on a data sample collected with the Belle detector with an integrated luminosity of 547.8 fb(-1).
125914561
Studies of gamma gamma to Lambda anti-Lambda , Sigma0 anti-Sigma0 production at Belle
125996923
Study of anti-B0 ---> D0 pi+ pi- decays
We report the results of a study of neutral B meson decays to the D^0 pi+ pi- final state, where the D^0 is fully reconstructed. The results are obtained from an event sample containing 388 million BB-bar -meson pairs collected in the Belle experiment at the KEKB e^+e^- collider. The total branching fraction of the three-body decay B(bar{B}^0 -> D^0 pi^+ pi^-) =(8.4+-0.4(stat.)+-0.8(syst.)) 10^{-4} has been measured. The intermediate resonant structure of these three-body decays has been studied. From a Dalitz plot analysis we have obtained the product of the branching fractions for D^{*+}_2 and D^{*+}_0 production: B(bar{B}^0-> D^{*+}_2 pi^-) B(D_2^{*+}-> D^{0}\pi^+)= (2.15+-0.17(stat.)+-0.29(syst.)+-0.12(mod.))10^{-4}, and B(bar{B}^0-> D^{*+}_0 pi^-) B(D_0^{*+}-> D^{0} pi^+)= (0.60+-0.13(stat.)}+-0.15(syst.)+-0.22(mod.))10^{-4}. This is the first observation of the bar{B}^0-> D^{*+}_0 pi^- decay. The bar{B^0} -> D^0 rho^0 and D^0f_2 branching fractions are measured to be: B(bar{B}^0->D^0 rho^0)=(3.19+-0.20(stat.)+-0.24(syst.)+-0.38(mod.)) 10^{-4},and B(bar{B}^0-> D^0 f_2)=(1.20+-0.18(stat.)+-0.21(syst.)+-0.32(mod.)) 10^{-4}.
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.