No Arabic abstract
Recently we derived a nonlinear U-spin amplitude relation for $D^0to P^+P^-$, $P=pi, K$, predicted to hold up to fourth order U-spin breaking terms of order $10^{-3}$. Here we study a similar relation for $D^0to V^+P^-, V =rho, K^*(892), P = pi, K$, expected to hold at an even higher accuracy of order $10^{-4}$. We confirm this prediction in spite of a large experimental error of about 20% in the amplitude of $D^0to K^{*+}pi^-$. We also comment briefly on U-spin breaking in $D^0to P^+V^-$.
An amplitude analysis of the decay $Lambda_b^0to D^0 p pi^-$ is performed in the part of the phase space containing resonances in the $D^0 p$ channel. The study is based on a data sample corresponding to an integrated luminosity of 3.0 fb$^{-1}$ of $pp$ collisions recorded by the LHCb experiment. The spectrum of excited $Lambda_c^+$ states that decay into $D^0 p$ is studied. The masses, widths and quantum numbers of the $Lambda_c(2880)^+$ and $Lambda_c(2940)^+$ resonances are measured. The constraints on the spin and parity for the $Lambda_c(2940)^+$ state are obtained for the first time. A near-threshold enhancement in the $D^0 p$ amplitude is investigated and found to be consistent with a new resonance, denoted the $Lambda_c(2860)^+$, of spin $3/2$ and positive parity.
An effective $SU(3)times SU(3)$ chiral lagrangian, which includes scalar resonances, is used to describe the process $D^+ rar K^- p^+ p^+$ at low-energies. Our main result is a set of five $S$-wave amplitudes, suited to be used in analyses of production data.
The finite range adiabatic wave approximation provides a practical method to analyze (d,p) or (p,d) reactions, however until now the level of accuracy obtained in the description of the reaction dynamics has not been determined. In this work, we perform a systematic comparison between the finite range adiabatic wave approximation and the exact Faddeev method. We include studies of $^{11}$Be(p,d)$^{10}$Be(g.s.) at $E_p=$5, 10 and 35 MeV; $^{12}$C(d,p)$^{13}$C(g.s.) at $E_d=$7, 12 and 56 MeV and $^{48}$Ca(d,p)$^{49}$Ca(g.s.) at $E_d=$19, 56 and 100 MeV. Results show that the two methods agree within $approx 5%$ for a range of beam energies ($E_d approx 20-40$ MeV) but differences increase significantly for very low energies and for the highest energies. Our tests show that ADWA agrees best with Faddeev when the angular momentum transfer is small $Delta l=0$ and when the neutron-nucleus system is loosely bound.
We have calculated the mass spectra for the $bar{D}_s^{(*)}D^{(*)}$ molecular states and $scbar qbar c$ tetraquark states with $J^P=0^+, 1^+, 2^+$. The masses of the axial-vector $bar{D}_sD^{*}$, $bar{D}_s^{*}D$ molecular states and $mathbf{1}_{[sc]} oplus mathbf{0}_{[bar q bar{c}]}$, $mathbf{0}_{[sc]} oplus mathbf{1}_{[bar q bar{c}]}$ tetraquark states are predicted to be around 3.98 GeV, which are in good agreement with the mass of $Z_{cs}(3985)^-$ from BESIII cite{besiii2020Zcs}. In both the molecular and diquark-antidiquark pictures, our results suggest that there may exist two almost degenerate states, as the strange partners of the $X(3872)$ and $Z_c(3900)$. We propose to carefully examine the $Z_{cs}(3985)$ in future experiments to verify this. One may also search for more hidden-charm four-quark states with strangeness not only in the open-charm $bar{D}_s^{(*)}D^{(*)}$ channels, but also in the hidden-charm channels $eta_c K/K^ast$, $J/psi K/K^ast$.
We present theoretical model comparison with published ALICE results for D-mesons (D$^0$, D$^+$ and D$^{*+}$) in $p$+$p$ collisions at $sqrt{s}$ = 7 TeV and $p$+Pb collisions at $sqrt{s_{NN}}$ = 5.02 TeV. Event generator HIJING, transport calculation of AMPT and calculations from NLO(MNR) and FONLL have been used for this study. We found that HIJING and AMPT model predictions are matching with published D-meson cross-sections in $p$+$p$ collisions, while both under-predict the same in $p$+Pb collisions. Attempts were made to explain the $R_{pPb}$ data using NLO-pQCD(MNR), FONLL and other above mentioned models.