14423824
Properties of color singlet chain states in e+ e- annihilation
We use the method of the color effective Hamiltonian to study the structure of color singlet chain states in ${N}_{c}=3$ and in the large ${N}_{c}$ limit. In order to obtain their total fraction when ${N}_{c}$ is finite, we illustrate how to orthogonalize these nonorthogonal states. We give numerical results for the fraction of orthogonalized states in ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}q\overline{q}\mathrm{gg}.$ With the help of a diagram technique, we derive their fraction up to ${O(1/N}_{c}^{2})$ for the general multigluon process. For large ${N}_{c}$ the singlet chain states correspond to well-defined color topologies. Therefore we may expect that the fraction of non-color-singlet-chain states is an estimate of the fraction of events where color reconnection is possible. In the case of soft gluon bremsstrahlung, we give an explicit form for the color effective Hamiltonian which leads to the dipole cascade formulation for parton showering in leading order in ${N}_{c}.$ The next-to-leading order corrections are also given for ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}q\overline{q}{g}_{1}{g}_{2}$ and ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}q\overline{q}{g}_{1}{g}_{2}{g}_{3}.$
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.
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.
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.
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.
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.
125202176
Study of the Y (4260) resonance in e+ e- collisions with initial state radiation at Belle
122551951
Search for B ---> tau nu and B ---> K nu anti-nu decays with a fully reconstructed B at Belle
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).
126039240
Observation of a new D(sJ) meson in B+ ---> anti-D0 D0 K+ decays
11572239
Observation of B decays to two kaons.
Using 449x10(6) BB[over ] pairs collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider, we observe clear signals for B(+)-->K[over ](0)K(+) and B(0)-->K[over ](0)K(0) decays with 5.3sigma and 6.0sigma significance, respectively. We measure the branching fractions B(B(+)-->K[over ](0)K(+))=(1.22(-0.28-0.16)(+0.32+0.13))x10(-6) and B(B(0)-->K[over ](0)K(0))=(0.87(-0.20)(+0.25)+/-0.09)x10(-6), and partial-rate asymmetries A(CP)(B(+)-->K[over ](0)K(+))=0.13(-0.24)(+0.23)+/-0.02 and A(CP)(B(0)-->K[over ](0)K(0))=-0.58(-0.66)(+0.73)+/-0.04. From a simultaneous fit, we also obtain B(B(+)-->K(0)pi(+))=(22.8(-0.7)(+0.8)+/-1.3)x10(-6) and A(CP)(B(+)-->K(0)pi(+))=0.03+/-0.03+/-0.01. The first and second error in the branching fractions and the partial-rate asymmetries are statistical and systematic, respectively. No signal is observed for B(0)-->K(+)K(-) decays, and for this branching fraction, we set an upper limit of 4.1x10(-7) at the 90% confidence level.