arXiv subjects

Jia-Jun Wu

Publications and source records attributed to Jia-Jun Wu.

108 records · Page 6Linked to original sources

arXiv2014

Finite-volume Hamiltonian method for coupled channel interactions in lattice QCD

Within a multi-channel formulation of $ππ$ scattering, we investigate the use of the finite-volume Hamiltonian approach to resolve scattering observables from lattice QCD spectra. The asymptotic matching of the well-known Lüscher formalism encodes a unique finite-volume spectrum. Nevertheless, in many practical situations, such as coupled-channel systems, it is advantageous to interpolate isolated lattice spectra in order to extract physical scattering parameters. Here we study the use of the Hamiltonian framework as a parameterisation that can be fit directly to lattice spectra. We find that with a modest amount of lattice data, the scattering parameters can be reproduced rather well, with only a minor degree of model dependence.

hep-lat↗

arXiv2014

Role of the possible $Σ^*(\frac{1}{2}^-)$ state in the $Λp \to Λp π^0$ reaction

The $Λp \to Λp π^0$ reaction near threshold is studied within an effective Lagrangian method. The production process is described by single-pion and single-kaon exchange. In addition to the role played by the $Σ^*(1385)$ resonance of spin-parity $J^P = 3/2^+$, the effects of a newly proposed $Σ^*$ ($J^P = 1/2^-$) state with mass and width around $1380$ MeV and $120$ MeV are investigated. We show that our model leads to a good description of the experimental data on the total cross section of the $Λp \to Λp π^0$ reaction by including the contributions from the possible $Σ^*(\frac{1}{2}^-)$ state. However, the theoretical calculations by considering only the $Σ^*(1385)$ resonance fail to reproduce the experimental data, especially for the enhancement close to the reaction threshold. On the other hand, it is found that the single-pion exchange is dominant. Furthermore, we also demonstrate that the angular distributions provide direct information of this reaction, hence could be useful for the investigation of the existence of the $Σ^*(\frac{1}{2}^-)$ state and may be tested by future experiments.

nucl-th↗

arXiv2013

Prediction of super-heavy $N^$ and $Λ^$ resonances with hidden beauty

The meson-baryon coupled channel unitary approach with the local hidden gauge formalism is extended to the hidden beauty sector. A few narrow $N^*$ and $Λ^*$ resonances around 11 GeV are predicted as dynamically generated states from the interactions of heavy beauty mesons and baryons. Production cross sections of these predicted resonances in $pp$ and $ep$ collisions are estimated as a guide for the possible experimental search at relevant facilities.

hep-ph↗

arXiv2013

Production of $J/Ψ$ on the nucleon and deuteron targets

A coupled-channel model with $πN$, $ρN$ and $J/ΨN$ channels is developed to predict the $π+ N \rightarrow J/Ψ+ N $ cross sections. The $J/Ψ$-$N$ interaction is parameterized in a form related to what has been predicted by the effective field theory approach and Lattice QCD. The other interactions within the model are constrained by the decay width of $J/Ψ\rightarrow ρ+ π$ and the total cross section data of $πN$ reactions. The calculated meson-baryon amplitudes are then used to predict the cross sections of the $J/Ψ$ production on the deuteron target by including the contributions from the impulse term and the one-loop calculations of the final $NN$ and $J/ΨN$ re-scattering effects. Predictions of the dependence of the cross sections of $π^- + p \rightarrow J/Ψ+ n$, $γ+ d \rightarrow J/Ψ+ n + p$, and $π^+ d \rightarrow J/Ψ+p +p$ on the $J/Ψ$-$N$ potentials are presented for experimental determinations of the $J/Ψ$-$N$ interaction. Within the vector meson dominance model, we have also applied the constructed coupled-channel model to predict the $γ+ p\rightarrow J/Ψ+ p$ cross sections near the $J/Ψ$ production threshold.

nucl-th↗

arXiv2013

Understanding the property of $η(1405/1475)$ in the $J/ψ$ radiative decay

In this work we make a systematic analysis of the correlated processes $J/ψ\to γη(1440)/f_1(1420)$ with $η(1440)/f_1(1420)\to K\bar{K}π$, $ηππ$ and $3π$, where the role played by the so-called "triangle singularity mechanism" (TSM) is clarified. Our results agree well with the experimental data and suggest a small fraction of $f_1(1420)$ contributions in these processes. This study confirms our conclusion in [Phys. Rev. Lett. 108, 081803 (2012)] that the dynamic feature of the TSM can be recognized by the strong narrow peak observed in the $ππ$ invariant mass spectrum of $η(1440)\to 3π$ with anomalously large isospin violations. Nevertheless, we explicitly demonstrate that the TSM can produce obvious peak position shifts for the same $η(1440)$ or $f_1(1420)$ state in different decay channels. This is a strong evidence that the $η(1405)$ and $η(1475)$ are actually the same state, i.e. $η(1440)$. We also make an analysis of the radiative decays of $η(1440)\to γV$ ($V=ϕ$, $ρ^0$ or $ω$) which shows that such a one-state prescription seems not to have a conflict with the so-far existing experimental data. Our analysis may shed a light on the long-standing puzzling question on the nature of $η(1405)$ and $η(1475)$.

hep-ph↗

arXiv2012

Production of Bound States with Hidden Charm at J-PARC and JLab

The cross sections of the production of bound states with hidden charm in reactions induced by pions and photons are presented. To facilitate the experimental efforts to determine the $J/Ψ$-N interactions, we present results for $J/Ψ$ production on the deuteron.

nucl-th↗

arXiv2012

Photo-production of Bound States with Hidden Charms

The photo-production of $J/Ψ$-$^3He$ bound state ($[^3He]_{J/Ψ}$) on a $^4He$ target has been investigated using the impulse approximation. The calculations have been performed using several $γ+N \rightarrow J/Ψ+N$ models based on the Pomeron-exchange and accounting for the pion-exchange mechanism at low energies. The $J/Ψ$ wavefunctions in $[^3He]_{J/Ψ}$ are generated from various $J/Ψ$-nucleus potentials which are constructed by either using a procedure based on the Pomeron-quark coupling mechanism or folding a $J/Ψ$-N potential ($v_{J/Ψ,N}$) into the nuclear densities. We consider $v_{J/Ψ,N}$ derived from the effective field theory approach, Lattice QCD, and Pomeron-quark coupling mechanism. The upper bound of the predicted total cross sections is about $0.1 - 0.3$ pico-barn. We also consider the possibility of photo-production of a six quark-$J/Ψ$ bound state ($[q^6]_{J/Ψ})$ on the $^3He$ target. The Compound Bag Model of $NN$ scattering and the quark cluster model of nuclei are used to estimate the $[q^6]$-N wavefunction in $^3He$ by imposing the condition that the calculated $^3He$ charge form factor must be consistent with what is predicted by the conventional nuclear model. The upper bound of the predicted total cross sections of $γ+ ^3He \rightarrow [q^6]_{J/Ψ} +N$ is about 2 - 4 pico-barn, depending on the model of $γ+N \rightarrow J/Ψ+N$ used in the calculations. Our results call for the need of precise measurements of $γ+p \rightarrow J/Ψ+p$ and also the $γ+^2H\rightarrow J/Ψ+n + p $ reactions near the threshold.

nucl-th↗

arXiv2012

The puzzle of anomalously large isospin violations in $η(1405/1475)\to 3π$

The BES-III Collaboration recently report the observation of anomalously large isospin violations in $J/ψ\to γη(1405/1475) \to γπ^0 f_0(980)\to γ+3π$, where the $f_0(980)$ in the $ππ$ invariant mass spectrum appears to be much narrower ($\sim$ 10 MeV) than the peak width ($\sim$50 MeV) measured in other processes. We show that a mechanism, named as triangle singularity (TS), can produce a narrow enhancement between the charged and neutral $K\bar{K}$ thresholds, i.e., $2m_{K^\pm}\sim 2m_{K^0}$. It can also lead to different invariant mass spectra for $η(1405/1475)\to a_0(980)π$ and $K\bar{K}^*+c.c.$, which can possibly explain the long-standing puzzle about the need for two close states $η(1405)$ and $η(1475)$ in $ηππ$ and $K\bar{K}π$, respectively. The TS could be a key to our understanding of the nature of $η(1405/1475)$ and advance our knowledge about the mixing between $a_0(980)$ and $f_0(980)$.

hep-ph↗

arXiv2012

Nucleon Resonances with Hidden Charm in Coupled-Channel Models

The model dependence of the predictions of nucleon resonances with hidden charm is investigated. We consider several coupled-channel models which are derived from relativistic quantum field theory by using (1) a unitary transformation method, and (2) the three-dimensional reductions of Bethe-Salpeter Equation. With the same vector meson exchange mechanism, we find that all models give very narrow molecular-like nucleon resonances with hidden charm in the mass range of 4.3 GeV $ < M_R < $ 4.5 GeV, in consistent with the previous predictions.

nucl-th↗

arXiv2011

Proposal and theoretical formalism for studying baryon radiative decays from J/ψ\to B^\bar B + \bar{B^}B \to γB\bar B

With accumulation of high statistics data at BESIII, one may study many new interesting channels. Among them, J/ψ\to B^*\bar B + \bar{B^*}B \to γB\bar B processes may provide valuable information of the radiative decays of the excited baryons (N^*,Λ^*,Σ^*,Ξ^*), and may shed light on their internal quark-gluon structure. Our estimation for the branching ratios of the nucleon excitations N^*(1440), N^*(1535) and N^*(1520) from the reaction J/ψ\to N^*\bar p + \bar N^* p \to γp\bar p, indicates that these processes can be studied at BESIII with 10^{10} J/ψevents. Explicit theoretical formulae for the partial wave analysis (PWA) of the J/ψ\to B^*\bar B +\bar B^* B with B^*\to B γand \bar B^*\to \bar Bγwithin covariant L-S Scheme are provided.

hep-ph↗

arXiv2011

Dynamically generated $N^{}$ and $Λ^$ resonances in the hidden charm sector around 4.3 GeV

The interactions of $\bar{D}Σ_{c}$-$\bar DΛ_c$, $\bar{D}^{*}Σ_{c}$-$\bar D^*Λ_c$, and related strangeness channels, are studied within the framework of the coupled channel unitary approach with the local hidden gauge formalism. A series of meson-baryon dynamically generated relatively narrow $N^*$ and $Λ^*$ resonances are predicted around 4.3 GeV in the hidden charm sector. We make estimates of production cross sections of these predicted resonances in $\bar{p} p $ collisions for PANDA at the forthcoming FAIR facility.

nucl-th↗

arXiv2010

Prediction of narrow $N^{}$ and $Λ^$ resonances with hidden charm above 4 GeV

The interaction between various charmed mesons and charmed baryons are studied within the framework of the coupled channel unitary approach with the local hidden gauge formalism. Several meson-baryon dynamically generated narrow $N^*$ and $Λ^*$ resonances with hidden charm are predicted with mass above 4 GeV and width smaller than 100 MeV. The predicted new resonances definitely cannot be accommodated by quark models with three constituent quarks and can be looked for at the forthcoming PANDA/FAIR experiments.

nucl-th↗

arXiv2010

Possible $Σ({1\over2}^-)$ under the $Σ^(1385)$ peak in $KΣ^$ photoproduction

The LEPS collaboration has recently reported a measurement of the reaction $γn\to K^+Σ^{*-}(1385)$ with linearly polarized photon beam at resonance region. The observed beam asymmetry is sizably negative at $E_γ=1.8-2.4 \mathrm{GeV}$, in contrast to the presented theoretical prediction. In this paper, we calculate this process in the framework of the effective Lagrangian approach. By including a newly proposed $Σ(J^P={1\over2}^-)$ state with mass around 1380~MeV, the experimental data for both $γn$ and $γp$ experiments can be well reproduced. It is found that the $Σ({1\over2}^-)$ and/or the contact term may play important role and deserve further investigation.

nucl-th↗

arXiv2009

Proposal for Studying $N^*$ Resonances with $\bar{p}p \to \bar{p}n π^+ $ Reaction

A theoretical study of $\bar{p}p \to \bar{p}n π^+ $ reaction for anti-proton beam energy from 1 to 4 GeV is made by including contributions from various known $N^*$ and $Δ^*$ resonances. It is found that for the beam energy around 1.5 GeV, the contribution of the Roper resonance $N^*_{(1440)}$ produced by the t-channel $σ$ exchange dominates over all other contributions. Since such reaction can be studied in the forthcoming $\bar{P}$ANDA experiment at Facility of Antiproton and Ion Research (FAIR), the reaction will be realistically the cleanest place for studying the properties of the Roper resonance and the best place for looking for other "missing" $N^*$ resonances with large coupling to $Nσ$.

hep-ph↗

arXiv2009

Further evidence for the $Σ^{*}$ resonance with $J^P=1/2^-$ around 1380 MeV

The unquenched quark models predict the new particle $Σ^*$ with spin parity $J^P=1/2^-$ and its mass is around the well established $Σ^*(1385)$ with $J^P=3/2^+$. Here by using the effective Lagrangian approach we study \kp\ reaction at the range of $Λ^{*}(1520)$ peak, comparing the resulting total cross section, and $π^+π^-$, $Λπ^+$, $Λπ^-$ invariant squared mass distributions for various incident $K^-$ momenta, as well as the production angular distribution of the $Λ$ with the data from the Lawrence Berkeley Laboratory 25-inch hydrogen bubble chamber, we find that, apart from the existing resonance $Σ^{*}(1385)$ with $J^P=3/2^+$, there is a strong evidence for the existence of the new resonance $Σ^{*}$ with $J^P=1/2^-$ around 1380 MeV. Higher statistic data on relevant reactions are needed to clarify the situation.

hep-ph↗

arXiv2009

Evidence for a new $Σ^{*}$ resonance with $J^P=1/2^-$ in the old data of $K^-p\toΛπ^+π^-$ reaction

Distinctive patterns are predicted by quenched quark models and unquenched quark models for the lowest SU(3) baryon nonet with spin parity $J^P=1/2^-$. While the quenched quark models predict the lowest $1/2^-$ $Σ^*$ resonance to be above 1600 MeV, the unquenched quark models predict it to be around $Σ^*(1385)$ energy. Here we re-examine some old data of the $\kp \to \la$ reaction and find that besides the well established $Σ^{*}(1385)$ with $J^P=3/2^+$, there is indeed some evidence for the possible existence of a new $Σ^{*}$ resonance with $J^P=1/2^-$ around the same mass but with broader decay width. Higher statistic data on relevant reactions are needed to clarify the situation.

hep-ph↗

arXiv2008

Study a0(980)-f0(980) mixing from a0(980) -> f0(980) transition

Various processes have been proposed previously to study a0(980)-f0(980) mixing through f0(980)->a0(980) transition. Here we investigate in detail the difference between a0(980)->f0(980) and f0(980)->a0(980) transitions. It is found that the a0(980)->f0(980) transition can provide additional constrains to the parameters of a0(980) and f0(980) mesons. Proposal is made to study a0(980)-f0(980) mixing from chi_{c1}->pi^0 a0(980) -> pi^0 f0(980) reaction at the upgraded Beijing electron positron collider with the BESIII detector.

hep-ph↗

arXiv2007

Possibility of measuring a0(980)-f0(980) mixing from J/psi -> phi a0

The a0(980)-f0(980) mixing intensity has been predicted to be in the range of 0.01 to 0.1 by various theoretical models, but lacking firm experimental observation. We examine the possibility of extracting the a0(980)-f0(980) mixing from J/psi -> phi f0 -> phi a0 reaction at upgraded Beijing Electron Positron Collider with BESIII detector. While the branching ratio of this process through the a0(980)-f0(980) mixing is expected to be about $O(10^{-6})$ similar to the estimated total amount from two background reactions J/psi -> gamma* -> phi a0 and J/psi -> K* K + c.c. -> phi a0, the peak width from the a0(980)-f0(980) mixing is about 8 MeV, much smaller than that from other mechanisms. With $10^9$ $J/ψ$ events at BESIII, the a0(980)-f0(980) mixing intensity is expected to be unambiguously and precisely measured.

hep-ph↗