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.
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.
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.
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.
126415460
Study of B+ ---> p anti-Lambda gamma, p anti-Lambda pi0 and B0 ---> p anti-Lambda pi-
125323507
Observation of B+ ---> proton anti-Lambda gamma
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}.
124969497
Measurement of branching fraction and CP asymmetry in B0 ---> rho0 pi0 decays
16290933
Pair-produced heavy particle topologies: MSSM neutralino properties at the LHC from gluino/squark cascade decays
Abstract.Processes of the form pp → anything → XiXj → $x\bar{x}$ + $y\bar{y}$ + notE are studied via a technique that may be viewed as an adaptation of time-honoured Dalitz plot analyses. Xi and Xj are new heavy states (with i, j =1, . . .,n), which may be identical or distinct; and $x\bar{x}$ and $y\bar{y}$ are necessarily distinct standard model (SM) fermion pairs whose invariant masses can be measured. A Dalitz-like plot of said invariant masses, $M(x\bar{x})$ versus $M(y\bar{y})$, exhibits a topology connected to the masses and specific decay chains of Xi and Xj. Aside from relatively minor details, observed patterns consist of a collection of box and wedge shapes. This collection is model-dependent: comparison of the observed pattern to the possibilities for a specific model yields information on which new particle pair combinations are actually being produced, information beyond that extractable from conventional one-dimensional invariant mass distributions. The technique is illustrated via application to the minimal supersymmetric standard model (MSSM) process pp → $ \tilde{g}\tilde{g},\tilde{g}\tilde{q},\tilde{q}\tilde{q} \to \widetilde{\chi}_i^0 \widetilde{\chi}_j^0$ → e+e- + μ+μ- notE. Here the heavy states are neutralinos $\widetilde{\chi}_i^0$ (i = 2,3,4) - note that $\widetilde{\chi}_1^0$ is excluded - which are produced in gluino/squark ($\tilde{g}$/$\tilde{q}$) cascade decay chains. Even with fairly modest expectations for the LHC performance during the first few years, this method still provides substantial insight into the neutralino mass spectrum and couplings if gluino/squark masses are relatively low (≃ 400 GeV).