J. P. Ma

Near Threshold Enhancement of p pbar System and p pbar Elastic Scattering

Abstract The observed enhancement of p p ¯ -production near the threshold in radiative decays of J / ψ and e + e − -annihilations can be explained with final state interactions among the produced N N ¯ system, where the enhancement is essentially determined by N N ¯ elastic scattering amplitudes. We propose to use an effective theory for interactions in an N N ¯ system near its threshold. The effective theory is similar to the well-known one for interactions in an NN system but with distinctions. It is interesting to note that in the effective theory some corrections to scattering amplitudes at tree-level can systematically be summed into a simple form. These corrections are from rescattering processes. With these corrected amplitudes we are able to describe the enhancement near the threshold in radiative decays of J / ψ and e + e − -annihilations, and the p p ¯ elastic scattering near the threshold.

Rescattering effect and near threshold enhancement of p(p)over-bar system

We study the observed enhancement of a p (p) over bar system near the threshold in the process J/psi -> gamma p (p) over bar and e(+)e(-) -> p (p) over tilde. From early studies the enhancement can be explained by final state interactions, which are in general taken into account with some potential models. In this work, we offer a simple approach within quantum field theory to explain the observed enhancement. We point out that among different final state interactions the rescattering in a N (N) over bar system though exchange of pi is the most important. The effects of the rescattering is completely fixed by the well- known coupling g(pi NN). Our results show that the enhancement in J/psi -> gamma p (p) over bar and e(+)e(-) -> p (p) over bar can be well described with the rescattering effects.

Production of X(3872) at PANDA

The recently discovered X(3872) has many possible interpretations. We study the production of X(3872) with PANDA at GSI for the antiproton-proton collision with two possible interpretations of X(3872). One is as a loosely bound molecule of D mesons, while another is a 2P charmonium state chi(c1(2P)). Using effective couplings we are able to give numerical predictions for the production near the threshold and the production associated with pi(0). We also study the possible background near the threshold production for X(3872)-> J/psi pi(+)pi(-). With the designed luminosity 1.5 fb(-1) per year of PANDA we find that the event number of p (p) over bar -> J/psi pi(+)pi(-) near the threshold is at the order of 10(6)-10(8). Our study shows that two interpretations are distinguishable from the line shape of the production.

Parity, charge conjugation, and SU(3) constraints on threshold enhancement in J / ψ decays into γ p p ¯ and K p Λ ¯

We study the threshold enhancement effects of baryon-antibaryon systems in J/{psi} decays at BES using parity P, charge conjugation C, and flavor SU(3) symmetries. The P and C symmetries restrict the pp in J/{psi}{yields}{gamma}pp to be in a state with C=+1, while the pp in J/{psi}{yields}{pi}{sup 0}pp to be with C=-1. Combining the C and P symmetries with flavor SU(3) symmetry, i.e., the CPS symmetry, we find that the {lambda}p system cannot be in 0{sup +} and 0{sup -} states in J/{psi}{yields}K{sup +}{lambda}p. We provide a consistent explanation of observation and nonobservation of near threshold enhancements in J/{psi}{yields}K{sup +}{lambda}p and J/{psi}{yields}{pi}{sup 0}pp, respectively. We also find that near baryon pair threshold enhancement can happen in several channels for J/{psi} decays and can be several times larger than that observed in J/{psi}{yields}K{sup +}{lambda}p in some channels.We study the threshold enhancement effects of baryon-anti-baryon systems in

Reexamining radiative decays of 1(--) quarkonium into eta(

J/psi

Relativistic corrections for polarizedJ/ψproduction inbdecay

decays at BES using parity

Color singlet relativistic correction in J/psi photoproduction

P

Transverse-momentum dependent factorization for gamma(*)pi(0)->gamma

, charge conjugation

QCD analysis of quark recombination for leading particle effect

C

Parity, Charge Conjugation and SU(3) Constraints on Threshold Enhancement in

, and flavor SU(3) symmetries. The