5502533
A trick to improve the efficiency of generating unweighted Bc events from BCVEGPY
In the present paper, we provide an addendum to improve the efficiency of generating unweighted events within PYTHIA environment for the generator BCVEGPY2.1 [C.H. Chang, J.X. Wang, X.G. Wu, Comput. Phys. Commun. 174 (2006) 241]. This trick is helpful for experimental simulation. Moreover, the BCVEGPY output has also been improved, i.e. one Les Houches Event common block has been added so as to generate a standard Les Houches Event file that contains the information of the generated Bc meson and the accompanying partons, which can be more conveniently used for further simulation.
28851116
GENXICC2.1: An improved version of GENXICC for hadronic production of doubly heavy baryons
We present an improved version of GENXICC, which is a generator for hadronic production of the doubly heavy baryons $\Xi_{cc}$, $\Xi_{bc}$ and $\Xi_{bb}$ and has been raised by C.H. Chang, J.X. Wang and X.G. Wu [Comput. Phys. Commun. 177 (2007) 467; Comput. Phys. Commun. 181 (2010) 1144]. In comparison with the previous GENXICC versions, we update the program in order to generate the unweighted baryon events more effectively under various simulation environments, whose distributions are now generated according to the probability proportional to the integrand. One Les Houches Event (LHE) common block has been added to produce a standard LHE data file that contains useful information of the doubly heavy baryon and its accompanying partons. Such LHE data can be conveniently imported into PYTHIA to do further hadronization and decay simulation, especially, the color-flow problem can be solved with PYTHIA8.0.
118425985
Spatial anisotropy: a method to study anisotropic flow in heavy ion collisions
We introduce a method to study anisotropic flow parameter vn as a collective probe to Quark Gluon Plasma in relativistic heavy ion collisions. The emphasis is put on the use of the Fourier expansion of initial spatial azimuthal distributions of participant nucleons in the overlapped region. The coefficients n of Fourier expansion are called the spatial anisotropy parameter for the n-th harmonic. We propose that collective dynamics can be studied by vn/n. In this paper, we will discuss in particular the second (n = 2) and the fourth (n = 4) harmonics.
118419281
Hadronic Trigger using electromagnetic calorimeter and particle identification at high-pT with STAR Detector
We derive a new method to improve the statistics of identified particles at high transverse momentum (\pt) using online-triggered events by the Barrel Electro-Magnetic-Calorimeter (BEMC) detector. The BEMC is used to select hadronic interaction and energy deposit from showers created by charged hadrons ($\pi^{\pm},K^{\pm}$ and $p$($\bar{p}$)) in the BEMC. With this trigger, the statistics of the high \pt particles are significantly enhanced by about a factor of 100 with selection efficiency up to 20%. In addition, resonant states ($\rho^0$, $K^{\star}$) and weak-decay V0 (\Ks and \La(\aLa)) can be constructed by selecting the BEMC-trigger hadron as one of its daughters. We also show that the trigger efficiency can be obtained reliably in simulation and data-driven approaches.
15351369
Charm production in deep inelastic scattering from threshold to high Q2
Charm final states in deep inelastic scattering constitute ~ 25% of the inclusive cross-section at small x as measured at HERA. These data can reveal important information on the charm and gluon structure of the nucleon if they are interpreted in a consistent perturbative QCD framework which is valid over the entire energy range from threshold to the high energy limit. We describe in detail how this can be carried out order-by-order in PQCD in the generalized MSbar formalism of Collins (generally known as the ACOT approach), and demonstrate the inherent smooth transition from the 3-flavor to the 4-flavor scheme in a complete order αs calculation, using a Monte Carlo implementation of this formalism. This calculation is accurate to the same order as the conventional NLO F2 calculation in the limit Q/mc >> 1. It includes the resummed large logarithm contributions of the 3-flavor scheme (generally known in this context as the fixed-flavor-number or FFN scheme) to all orders of αsln (mc2/Q2). For the inclusive structure function, comparison with recent HERA data and the existing FFN calculation reveals that the relatively simple order-αs (NLO) 4-flavor (mc≠0) calculation can, in practice, be extended to rather low energy scales, yielding good agreement with data over the full measured Q2 range. The Monte Carlo implementation also allows the calculation of differential distributions with relevant kinematic cuts. Comparisons with available HERA data show qualitative agreement; however, they also indicate the need to extend the calculation to the next order to obtain better description of the differential distributions.
120435997
High-pT hadronic trigger using electromagnetic calorimeter with the STAR detector
Abstract We derive a new method to improve the statistics of identified particles at high transverse momentum ( p T ) using online-triggered events by the STAR Barrel electro-magnetic-calorimeter (BEMC) detector. The BEMC is used to select charged hadrons ( π ± , K ± , and p ( p ¯ ) ) via hadronic shower energy deposited in the BEMC. With this trigger, the statistics of the high p T particles are significantly enhanced (by a factor of up to ∼ 100 for STAR) with trigger efficiency up to 20%. In addition, weak-decay V0s ( K S 0 and Λ ( Λ ¯ ) ) can be reconstructed by selecting the BEMC-trigger hadron as one of the decay daughters. We also show that the trigger efficiency can be obtained reliably in simulation and data-driven approaches, and final results from new method are compared with previous published results.
121898607
HNC Theory for Shadow Wave Functions
The hyper-netted-chain theory is applied to the study of strongly interacting Bose and Fermi systems described by the shadow-correlated wave functions. A new class of shadow wave functions is also proposed which, in spite of their greater generality, requires a much simpler HNC scheme to compute distribution functions, density matrices and the energy expectation value. Moreover, HNC-theory allows for a full optimization of the correlations functions, particularly in the case of this new class of extended shadow wavefunctions. Possible applications of the shadow wave functions to the study of the Fractional Quantum Hall effect are also discussed.