arXiv subjects

J. P. Ma

Publications and source records attributed to J. P. Ma.

100 records · Page 6Linked to original sources

arXiv1995

A Nonperturbative Study of Quarkonium Systems

Using Nonrelativistic QCD on the lattice we studied the mass spectrum of quarkonium systems nonperturbatively for a range of the bar quark mass. We determined two products of the matrix elements involved in quarkonium decays and studied the mass dependence of the results. We predict from our calculations the leptonic decay width of $Υ$, and use the mass dependence to predict the leptonic decay width of $J/ψ$. These calculations agree with the experimental results. In lattice NRQCD an additional parameter $n$ is introduced, and we study the sensitivity of our results to the choice of $n$.

hep-ph↗

arXiv1995

Quark Fragmentation into ^3P_J Quarkonium

We calculate the functions of parton fragmentation into $^3P_J$ quarkonium at order $α_s ^2$, where the parton can be a heavy or light quark. The obtained functions explicitly satisfy the Altarelli-Parisi equation and they are divergent, behaving as $z^{-1}$ near $z=0$. However, if one choses the renormalization scale as twice of the heavy quark mass, the fragmentation functions are regular over the whole range of $z$.

hep-ph↗

arXiv1994

CP Violating Effects in $e^+e^-\rightarrow ZH$ and Their Optimization

We consider the possibilities of testing CP conservation in the process $e^+e^- \rightarrow ZH$. The easiest is to measure the forward-backward asymmetry of the $Z$ boson, a nonzero value of which signals CP violation. The effects of CP violation are predicted in the two Higgs doublet model. We show here that a choise of optimal observables can improve the possibility of observing CP violation. Although the number of events is not large, useful information about CP violating parameters can be extracted.

hep-ph↗

arXiv1994

Transverse Polarization of Top Quarks Produced at a Photon-Photon Collider

At future $γγ$ colliders copious production of $t \bar{t}$ pairs is possible. This would allow a detailed investigation of the interactions involving the top quark. We propose some orrelations which are sensitive to $t \bar{t}$ final state interactions and we compute the QCD and standard model Higgs boson contributions to these correlations. QCD induced transverse polarization of top quarks is found to be sizeable and measurable at a high-energy $e^+e^-$ collider with an integrated luminosity of 10 $({\rm fb})^{-1}$ which is converted into a photon collider by backscattering of laser photons.

hep-ph↗

arXiv1994

Calculating Fragmentation Functions from Definitions

Fragmentation functions for hadrons composed of heavy quarks are calculated directly from the definitions given by Collins and Soper and are compared with those calculated in another way. A new fragmentaion function for a P-wave meson is also obtained and the singularity arising at the leading order is discussed.

hep-ph↗

arXiv1993

CP Violation in Fermion Pair Decays of Neutral Boson Particles

We study CP violation in fermion pair decays of neutral boson particles with spin 0 or 1. We study a new asymmetry to measure CP violation in $η, K_L \rightarrow μ^+μ^-$ decays and discuss the possibility of measuring it experimentally. For the spin-1 particles case, we study CP violation in the decays of $J/ψ$ to $SU(3)$ octet baryon pairs. We show that these decays can be used to put stringent constraints on the electric dipole moments of $Λ$, $Σ$ and $Ξ$.

hep-ph↗

arXiv1993

CP Test in the W Pair Production via Photon Fusion at NLC

We study the possibility to test CP invariance in the $W^+W^-$ production via photon fusion at NLC. The predictions of the CP violation effects are made within two Higgs doublet extensions of the minimal standard model, where CP violation is introduced by a neutral Higgs exchange in s channel in our case. The width effect in the Higgs propagator on the CP violation effects is studied in detail. The CP violation effects can be measured in some parameter region of the extensions.

hep-ph↗

arXiv1993

CP violation in Higgs decays

We study CP violation in fermion pair decays of Higgs boson. We idenfy some CP odd observables related to the tree level decay amplitude. We find that a few thousand Higgs boson decay events can already provide important information about CP violation. If the Higgs boson is produced, such an analysis could be carried out at the SSC, LHC and NLC.

hep-ph↗

arXiv1992

CP violation in $J/ψ\rightarrow Λ\bar Λ$

We study CP violation in $J/ψ\rightarrow Λ\barΛ$ decay. This decay provides a good place to look for CP violation. Some observables are very sensitive to the $Λ$ electric dipole moment $d_Λ$ and therefore can be used to improve the experimental upper bound on $d_Λ$. CP violations in the lepton pair decays of $J/ψ$ and $Υ$ are also discussed.

hep-ph↗

arXiv1992

CP Violating Form Factors for Three Gauge Boson Vertex in the Two Higgs Doublet and Left-Right symmetric Models

In this paper we calculate the one loop contributions to the CP violating three gauge boson couplings in two-Higgs doublet and Left--Right symmetric models. In the two-Higgs doublet model only a P conserving and CP violating coupling is generated, and it can be large as $10^{-3}$. In the Left--Right symmetric model both P conserving and violating couplings are generated. Due to constraints on the $W_L$--$W_R$ mixing, these couplings are small.

hep-ph↗