arXiv subjects

W. Xie

Publications and source records attributed to W. Xie.

40 records · Page 3Linked to original sources

arXiv2014

Unified Hamiltonian model for mesons and baryons

A new Hamiltonian model is introduced to study the spectrum of light hadrons. It combines relativistic field theory with elements of the constituent quark model. In addition to the standard linear confining and pseudoscalar meson exchange interactions with predetermined parameters, an additional interaction with different covariant spin structures is examined. Using a large scale Monte Carlo variational procedure, the resulting model Hamiltonian provides a very good, unified description of the light quark baryon (both octet and decuplet) and meson spectra.

hep-ph↗

arXiv2013

Coulomb gauge model for hidden charm tetraquarks

The spectrum of tetraquark states with hidden charm is studied within an effective QCD Coulomb gauge Hamiltonian approach. Of the four independent color schemes, two are investigated, the $(q\bar{c})_1(c\bar{q})_1$ singlet-singlet (molecule) and the $(qc)_3(\bar{q}\bar{c})_3$ triplet-triplet (diquark), for selected $J^{PC}$ states using a variational method. The predicted masses of triplet-triplet tetraquarks are roughly a GeV heavier than the singlet-singlet states. There is also an interesting flavor dependence with $(q\bar{q})_1(c\bar{c}_1)$ states about half a GeV lighter than $(q\bar{c})_1(\bar{q}c)_1$. The lightest $1^{++}$ and $1^{--}$ predictions are in agreement with the observed X(3872) and Y(4008) masses, respectively, suggesting they both have a $ωJ/ ψ$ rather than $D^*\bar D^*$ molecular type structure. This is consistent with observed $X$, $Y$ decays to $π^\pm J/ ψ$ and not $D^*\bar D^*$ .

hep-ph↗

arXiv2011

A Reaction Plane Detector for PHENIX at RHIC

A plastic scintillator paddle detector with embedded fiber light guides and photomultiplier tube readout, referred to as the Reaction Plane Detector (RXNP), was designed and installed in the PHENIX experiment prior to the 2007 run of the Relativistic Heavy Ion Collider (RHIC). The RXNP's design is optimized to accurately measure the reaction plane (RP) angle of heavy-ion collisions, where, for mid-central $\sqrt{s_{NN}}$ = 200 GeV Au+Au collisions, it achieved a $2^{nd}$ harmonic RP resolution of $\sim$0.75, which is a factor of $\sim$2 greater than PHENIX's previous capabilities. This improvement was accomplished by locating the RXNP in the central region of the PHENIX experiment, where, due to its large coverage in pseudorapidity ($1.0<|η|<2.8$) and $ϕ$ (2$π$), it is exposed to the high particle multiplicities needed for an accurate RP measurement. To enhance the observed signal, a 2-cm Pb converter is located between the nominal collision region and the scintillator paddles, allowing neutral particles produced in the heavy-ion collisions to contribute to the signal through conversion electrons. This paper discusses the design, operation and performance of the RXNP during the 2007 RHIC run.

nucl-ex↗

arXiv2005

Study of $J/ψ$ Production in $\sqrt{s_{NN}} = 200$ GeV $p+p$ and $d+Au$ Collisions in PHENIX

$J/ψ$ measurements in $p+p$ and $d+Au$ collisions serve as crucial references to understand the $J/ψ$ production in $Au+Au$ collisions at RHIC where quark gluon plasma (QGP) is expected to be formed. They also provide important clues to study various interesting phenomena such as the gluon shadowing and color glass condensate. We report the latest results from PHENIX experiment on $J/ψ$ production in $p+p$ and $d+Au$ collisions at forward, backward and midrapidity.

nucl-ex↗