115989990
Contribution of color singlet process upsilon ---> J / psi + c anti-c g to upsilon ---> J / psi + X
We show that the colour-singlet process $\Upsilon \to J/\Psi + c\bar{c}g$ significantly contributes to the inclusive process $\Upsilon \to J/\Psi + X$. We calculate the partial width and the momentum distribution of the produced $J/\Psi$ in this channel. The obtained width is comparable to the experimental data. The momentum distribution is fairly soft, which is in contrast to the results from the colour-octet processes discussed earlier in literature but is consistent with the CLEO measurements. Further experiments to check this contribution are suggested.
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.
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.
46391101
Determination of /Vub/ from measurements of the inclusive charmless semileptonic partial rates of B mesons using full reconstruction tags.
We present a measurement of the Cabibbo-Kobayashi-Maskawa matrix element /Vub/, based on 253 fb(-1) of data collected by the Belle detector at the KEKB e+ e- asymmetric collider. Events are tagged by fully reconstructing one of the B mesons, produced in pairs from Gamma(4S). The signal for b --> u semileptonic decay is distinguished from the b --> c background using the hadronic mass Mx, the leptonic invariant mass squared q2 and the variable P+ [triple bond] Ex - /px/. The results are obtained for events with p(l)* > or = 1 GeV/c, in three kinematic regions (1) Mx < 1.7 GeV/c2, (2) Mx < 1.7 GeV/c2 combined with q2 > 8 GeV2/c2, and by (3) P+ < 0.66 GeV/c. The matrix element /Vub/ is found to be (4.09 +/- 0.19 +/- 0.20(+0.14) -0.15 +/- 0.18) x 10(-3), where the errors are statistical, systematic including Monte Carlo modeling, theoretical, and from shape function parameter determination, respectively.
122738195
Measurement of masses and branching ratios of Xi(+)(c) and Xi(0)(c) baryons
Reference EPFL-ARTICLE-154475doi:10.1016/j.physletb.2004.11.038View record in Web of Science Record created on 2010-11-05, modified on 2017-05-12
125667466
Observation of B0 ---> D+(s) pi-
126239408
Observation of B+ ---> K(1)(1270)+ gamma
123671853
Studies of CP violation in B0 ---> J / psi K*0 decays