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B. S. Zou

Publications and source records attributed to B. S. Zou.

At least 37 records · Page 2Linked to original sources
arXiv2011

I=0, C=-1 mesons from 1940 to 2410 MeV

New Crystal Barrel data are reported for pbar-p -> omega-eta and pbar-p -> omega-pizero-pizero with omega decaying to piplus-piminus-pizero. The omega-eta data confirm angular distributions obtained earlier from data where omega -> pizero-gamma. The new omega-eta data provide accurate measurements of vector and tensor polarisations of the omega and lead to considerable improvements in masses and widths of s-channel resonances. A new J^PC = 3^+- I = 0 resonance is observed with mass M = 2025+-20 MeV and width Gamma = 145+-30 MeV. Polarisation is close to zero everywhere and tensor polarisations are large, as is the case also for pbar-p -> omega-pizero.

hep-ex↗
arXiv2011

Combined analysis of meson channels with I=1, C = -1 from 1940 to 2410 MeV

New Crystal Barrel data are reported for pbar-p -> omega-pizero and pbar-p -> omega eta-pizero with omega decaying to piplus-piminus-pizero. The shapes of angular distributions agree well with those for data where omega -> pizero-gamma; this is a valuable cross-check on systematic errors. The new data provide good measurements of vector and tensor polarisations P_y, T20, T21 and T22 of the omega. These lead to significant improvements in parameters of several resonances reported earlier. New values of masses and widths (in Mev) are: J^PC = 5^-- (2300+-45, 260+-75), J^PC = 3^-- (2260+-20, 160+-25), J^PC = 1^+- (2240+-35, 320+-85), and J^PC = 1^-- (2110+-35, 230+-50). A remarkable feature of the data is that vector polarisation P_y is close to zero everywhere. It follows that all interfering amplitudes have relative phases close to 0 or 180 deg. Tensor polarisations are large.

hep-ex↗
arXiv2011

A study of pbar-p -> eta-eta-eta for masses 1960 to 2410 MeV

Data on pbar-p -> 3eta for beam momenta 600--1940 MeV/c are presented. The strongest channel is f_0(1500)-eta from the initial pbar-p state 1S0. Together with eta-pizero-pizero data, the 3eta data determine the branching ratio BR[f_0(1500) -> eta-eta]/BR[f_0(1500) -> pizero-pizero] = 0.42+-0.09. They are consistent with a dominant contribution from an I=0, C=+1 J^{PC} = 0^{-+} resonance observed earlier in the eta-pizero-pizero data; from the combined eta-pizero-pizero and 3eta data, its mass is M = 2320 \pm 15 MeV and its width Gamma = 230+-35 MeV.

hep-ex↗
arXiv2011

The f2(1565) in pbar-p -> (omega-omega)pizero interactions at rest

Data are presented on the reaction pbar-p -> omega-omega-pizero at rest from the Crystal Barrel detector. These data identify a strong signal due to f2(1565) -> omega-omega. The relative production from initial pbar-p states 3P2, 3P1 and 1S0 is well determined from omega-omega decay angular correlations; P-state annihilation dominates strongly. A combined fit is made with data on pbar-p -> 3pizero at rest, where f2(1565) -> pizero-pizero is observed.

hep-ex↗
arXiv2011

Resonances formed by pbar-p and decaying into pizero-pizero-eta for masses 1960 to 2410 MeV

Data on pbar-b annihilation in flight into pizero-pizero-eta are presented for nine beam momenta 600 to 1940 MeV/c. The strongest four intermediate states are found to be f_2(1270)-eta, a_2(1320)-pi, sigma-eta and a_0(980)-pi. Partial wave analysis is performed mainly to look for resonances formed by pbar-p and decaying into pizero-pizero-eta through these intermediate states. There is evidence for the following s-channel I = 0 resonances : two 4^{++} resonances with mass and width (M,Gamma) at (2044, 208) MeV and (2320+-30, 220+-30) MeV; three 2^{++} resonances at (2020+-50, 200+-70) MeV, (2240+-40, 170+-50) MeV and (2370+-50, 320+-50) MeV; two 3^{++} resonances at (2000+-40, 250+-40) MeV and (2280+-30, 210+-30) MeV; a 1^{++} resonance at (2340+-40, 340+-40) MeV; and two 2^{-+} resonances at (2040+-40, 190+-40) MeV and (2300+-40, 270+-40) MeV.

hep-ex↗
arXiv2011

Partial wave analysiss of pbar-p -> piminus-piplus, pizero-pizero, eta-eta and eta-etaprime

A partial wave analysis is presented of Crystal Barrel data on pbar-p -> pizero-pizero, eta-eta and eta-etaprime from 600 to 1940 MeV/c, combined with earlier data on dσ/dΩand P for pbar-p->piminus-piplus. The following s-channel I=0 resonances are identified: (i) J^{PC} = 5^{--} with mass and width (M,Γ) at (2295+-30,235^{+65}_{-40}) MeV, (ii) J^{PC} = 4^{++} at (2020+-12, 170+-15) MeV and (2300+-25, 270+-50) MeV, (iii) 3D3 JPC = 3^{--} at (1960+-15, 150+-25) MeV and (2210+-4$, 360+-55) MeV, and a 3G3 state at (2300 ^{+50}_{-80}, 340+-150) MeV, (iv) JPC = 2^{++} at (1910+-30, 260+-40) MeV, (2020+-30, 275+-35) MeV, (2230+-30, 245+-45) MeV, and (2300+-35, 290+-50) MeV, (v) JPC = 1^{--} at (2005+-40, 275+-75) MeV, and (2165+-40, 160 ^{+140}_{-70}) MeV, and (vi) JPC = 0^{++} at (2005+-30, 305+-50) MeV, (2105+-15, 200+-25) MeV, and (2320+-30, 175+-45) MeV. In addition, there is a less well defined 6^{++} resonance at 2485+-40 MeV, with Gamma = 410+-90 MeV. For every JP, almost all these resonances lie on well defined linear trajectories of mass squared v. excitation number. The slope is 1.10+-0.03 Gev^2 per excitation. The f_0(2105) has strong coupling to eta-η, but much weaker coupling to pizero-pizero. Its flavour mixing angle between q-qbar and s-sbar is (59-71.6)deg, i.e. dominant decays to s-sbar. Such decays and its strong production in pbar-p interactions strongly suggest exotic character.

hep-ex↗
arXiv2011

I = 0 C = +1 mesons from 1920 to 2410 MeV

A combined fit is presented to data on pbar-p annihilation in flight to final states eta-pizero-pizero, pizero-pizero, eta-eta, eta-etaprime and piminus-piplus. The emphasis lies in improving an earlier study of eta-pizero-pizero by fitting data at nine pbar momenta simultaneously and with parameters consistent with the two-body channels. There is evidence for all of the I=0, C=+ q-qbar states expected in this mass range. New resonances are reported with masses and widths M,Gamma as follows: JPC = 4^{-+} (2328+-38, Gamma=240+-90) MeV, 1^{++} (1971+-15, 240+-45) MeV, 0^{-+} (2285+-20, 325+-30) MeV, and 0^{-+} (2010 ^{+35}_{-60}, 270+-60) MeV. Errors on the masses and widths of other resonances are also reduced substantially. All states lie close to parallel straight line trajectories of excitation number v. mass squared.

hep-ex↗
arXiv2011

Analysis of the new Crystal Ball data on $K^-p\toπ^0Λ$ reaction with beam momenta of $514\sim 750$ MeV/$c$

The Crystal Ball Collaboration has recently reported the differential cross sections and $Λ$ polarization for the reaction $K^-p\rightarrow π^0Λ$ using an incident $K^-$ beam with momenta between 514 and 750 MeV/$c$. We make a partial wave analysis for this process with an effective Lagrangian approach and study the properties of some $Σ$ resonances around this energy range. With the inclusion of the 4-star resonances $Σ(1189)$, $Σ^*(1385)$, $Σ(1670){3\over 2}^-$, $Σ(1775){5\over 2}^-$, as well as a $Σ(1635){1\over 2}^+$, which is compatible with the 3-star $Σ(1660){1\over 2}^+$ in PDG, our results can well reproduce the experimental data. The parameters on the $Σ$ resonances and related couplings are studied.

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

Study of the $J/ψ\to ϕ(ω) f_2(1270)$, $J/ψ\to ϕ(ω) f'_2(1525)$ and $J/ψ\to K^{*0}(892) \bar{K}^{* 0}_2(1430)$ decays

We present an approach to study the decay modes of the $J/ψ$ into a vector meson and a tensor meson, taking into account the nature of the $f_2(1270)$, $f'_2(1525)$, $\bar{K}^{* 0}_2(1430)$ resonances as dynamically generated states from the vector meson-vector meson interaction. We evaluate four ratios of partial decay widths in terms of a flavor dependent OZI breaking parameter and the results obtained compare favorably with experiment. The fit to the data is possible due to the particular strength and sign of the couplings of the resonances to pairs of vector mesons given by the theory, thus providing a nontrivial test for the idea of these tensor states as dynamically generated from the vector-vector interaction.

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↗
arXiv2010

Study of the $f_2(1270)$, $f_2'(1525)$, $f_0(1370)$ and $f_0(1710)$ in the $J/ψ$ radiative decays

In this paper we present an approach to study the radiative decay modes of the $J/ψ$ into a photon and one of the tensor mesons $f_2(1270)$, $f'_2(1525)$, as well as the scalar ones $f_0(1370)$ and $f_0(1710)$. Especially we compare predictions that emerge from a scheme where the states appear dynamically in the solution of vector meson--vector meson scattering amplitudes to those from a (admittedly naive) quark model. We provide evidence that it might be possible to distinguish amongst the two scenarios, once improved data are available.

hep-ph↗
arXiv2010

Five-quark components in baryons

Evidence has been accumulating for the existence of significant intrinsic non-perturbative five-quark components in various baryons. The inclusion of the five-quark components gives a natural explanation of the excess of $\bar d$ over $\bar u$, significant quark orbital angular momentum in the proton, the problematic mass and decay pattern of the lowest $1/2^-$ baryon nonet, etc.. A breathing mode of $qqq\leftrightarrow qqqq\bar q$ is suggested for the lowest $1/2^-$ baryon octet. Evidence of a predicted member of the new scheme, $Σ^*(1/2^-)$ around 1380 MeV, is introduced.

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↗