Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userInterpretation of Axial Resonances in J/psi-phi at LHCb
89
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We suggest that the J/psi phi structures observed by LHCb can be fitted in two tetraquak multiplets, the S-wave ground state and the first radial excitation, with composition [cs][cbar sbar]. When compared to the previously identified [cq][cbar qbar] multiplet, the observed masses agree with what expected for a multiplet with q -->s. We propose the X(4274), fitted by LHCb with a single 1^++ resonance, to correspond rather to two, almost degenerate, unresolved lines with J^PC = 0^++, 2^++. Masses of missing particles in the 1S and 2S multiplets are predicted.
rate research
Read More
A comment on the LHCb discovery of J/psi-pair resonances. To appear in Science Bulletin as a NEWS and VIEWS Paper.
The first observation of exotic states with a new quark content $c bar{c} u bar{s}$ decaying to the $J/psi K^+$ final state is reported with high significance from an amplitude analysis of the $B^+ to J/psi phi K^+$ decay. The analysis is carried out using proton-proton collision data corresponding to a total integrated luminosity of 9 fb$^{-1}$ collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV. The most significant state, $Z_{cs}(4000)^+$, has a mass of $4003pm6,^{+,phantom{0}4}_{-,14}$ MeV, a width of $131pm15pm26$ MeV, and spin-parity $J^P=1^+$, where the quoted uncertainties are statistical and systematic, respectively. A new $1^+$ $X(4685)$ state decaying to the $J/psi phi$ final state is also observed with high significance. In addition, the four previously reported $J/psi phi$ states are confirmed and two more exotic states, $Z_{cs}(4220)^+$ and $X(4630)$, are observed with significance exceeding five standard deviations.
The two exotic $P_c^+(4380)$ and $P_c^+(4450)$ discovered in $2015$ by the LHCb Collaboration, together with the four resonances $X(4140)$, $X(4274)$, $X(4500)$ and $X(4700)$, reported in $2016$ by the same collaboration, are described in a constituent quark model which has been able to explain the properties of charmonium states from the $J/psi$ to the $X(3872)$. Using this model we found a $bar DSigma_c^*$ bound state with $J^P=frac{3}{2}^-$ that may be identified with the $P_c^+(4380)$. In the $bar D^*Sigma_c$ channel we found three possible candidates for the $P_c^+(4450)$ with $J^P=frac{1}{2}^-$, $frac{3}{2}^-$ and $frac{3}{2}^+$ with almost degenerated energies. The $X(4140)$ resonance appears as a cusp in the $J/psiphi$ channel due to the near coincidence of the $D_{s}^{pm}D_{s}^{astpm}$ and $J/psiphi$ mass thresholds. The remaining three $X(4274)$, $X(4500)$ and $X(4700)$ resonances appear as conventional charmonium states with quantum numbers $3^{3}P_{1}$, $4^{3}P_{0}$ and $5^{3}P_{0}$, respectively; and whose masses and widths are slightly modified due to their coupling with the corresponding closest meson-meson thresholds.
Structure in the di-$J/psi$ mass spectrum observed by the LHCb experiment around 6.9 and 7.2 GeV is interpreted in terms of $J^{PC}=0^{++}$ and $2^{++}$ resonances between a $cc$ diquark and a $bar c bar c$ antidiquark, using a recently confirmed string-junction picture to calculate tetraquark masses. The main peak around 6.9 GeV is likely dominated by the $0^{++}(2S)$ state, a radial excitation of the $cc$-$bar c bar c$ tetraquark, which we predict at $6.871pm 0.025$ GeV. The dip around 6.75 GeV is ascribed to the opening of the Swave di-$chi_{c0}$ channel, while the dip around 7.2 GeV could be correlated with the opening of the di-$eta_c(2S)$ or $Xi_{cc} bar Xi_{cc}$ channel. The low-mass part of the di-$J/psi$ structure appears to require a broad resonance consistent with a predicted $2^{++}(1S)$ state with invariant mass around $M_{rm inv} = 6400$ MeV. Implications for $bb bar b bar b$ tetraquarks are discussed.
Based on a sample of $2.25times 10^{8} J/psi$ events taken with the BESIII detector at the BEPCII collider, we present the results of a study of the decay $J/psito eta phipi^{+}pi^{-}$. The $Y(2175)$ resonance is observed in the invariant mass spectrum of $phi f_{0}(980)$ with a statistical significance of greater than $10sigma$. The corresponding mass and width are determined to be $M=2200pm 6 mathrm{(stat.)} pm 5mathrm{(syst.)} mathrm{MeV}/c^{2}$ and $Gamma=104pm 15mathrm{(stat.)}pm 15mathrm{(syst.)}$ MeV, respectively, and the product branching fraction is measured to be $mathcal{B}(J/psitoeta Y(2175)$, $Y(2175)to phi f_{0}(980)$, $f_{0}(980)to pi^{+}pi^{-})= (1.20pm 0.14mathrm{(stat.)}pm 0.37 mathrm{(syst.)})times 10^{-4}$. The results are consistent within errors with those of previous experiments. We also measure the branching fraction of $J/psito phi f_1(1285)$ with $f_1(1285)to etapi^{+}pi^{-}$ and set upper limits on the branching fractions for $J/psito phieta(1405)$/$phi X(1835)$/$phi X(1870)$ with $eta(1405)$/$X(1835)$/$X(1870)to etapi^{+}pi^{-}$ at the 90% confidence level.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
