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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2020). Search for the doubly charmed baryon Xi(+)(cc). Sci. China-Phys. Mech. Astron., 63(2), 221062–15pp.
Abstract: A search for the doubly charmed baryon.+ cc is performed through its decay to the.+ c K- p+ final state, using proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV. The data correspond to a total integrated luminosity of 9 fb-1. No significant signal is observed in the mass range from 3.4 to 3.8 GeV/c2. Upper limits are set at 95% credibility level on the ratio of the.+ cc production cross-section times the branching fraction to that of.+ c and.++ cc baryons. The limits are determined as functions of the.+ cc mass for di fferent lifetime hypotheses, in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 4 to 15 GeV/c.
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Molina, R., Ikeno, N., & Oset, E. (2023). Sequential single pion production explaining the dibaryon “d*(2380)” peak. Chin. Phys. C, 47(4), 041001–10pp.
Abstract: In this study, we investigate the two step sequential one pion production mechanism, that is, np(I=0)->pi(-)pp followed by the fusion reaction pp ->pi(+)d, to describe the np ->pi(+)pi(-)d reaction with in state I = 0 . In this reaction, a narrow peak identified with a “ d(2380) ” dibaryon has been previously observed. We discover that the second reaction step pp ->pi(+)d is driven by a triangle singularity that determines the position of the peak of the reaction and the high strength of the cross section. The combined cross section of these two mechanisms produces a narrow peak with a position, width, and strength, that are compatible with experimental observations within the applied approximations made. This novel interpretation of the peak accomplished without invoking a dibaryon explains why this peak has remained undetected in other reactions.
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Garcilazo, H., Valcarce, A., & Vijande, J. (2020). Xi(-)t quasibound state instead of Lambda Lambda nn bound state. Chin. Phys. C, 44(2), 024102–7pp.
Abstract: The coupled Lambda Lambda nn – Xi-pnn system was studied to investigate whether the inclusion of channel coupling is able to bind the Lambda Lambda nn system. We use a separable potential three-body model of the coupled Lambda Lambda nn – Xi-pnn system and a variational four-body calculation with realistic interactions. Our results exclude the possibility of a bound state by a large margin. Instead, we found a Xi(-)t quasibound state above the Lambda Lambda nn threshold.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2020). Measurement of Xi(++)(cc) production in pp collisions at root s=13 TeV. Chin. Phys. C, 44(2), 022001–11pp.
Abstract: The production of Xi(++)(cc) baryons in proton-proton collisions at a centre-of-mass energy of root s = 13 Tev is measured in the transverse-momentum range 4 < p(T) < 15 GeV/c and the rapidity range 2.0 < y < 4.5. The data used in this measurement correspond to an integrated luminosity of 1.7 fb(-1), recorded by the LHCb experiment during 2016. The ratio of the Xi(++)(cc) production cross-section times the branching fraction of the Xi(++)(cc) -> Lambda K-+(c)-pi(+)pi(+) decay relative to the prompt Lambda(+)(c) production cross-section is found to be (2.22 +/- 0.27 +/- 0.29) x 10(-4), assuming the central value of the measured Xi(++)(cc) lifetime, where the first uncertainty is statistical and the second systematic.
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Dias, J. M., Yu, Q. X., Liang, W. H., Sun, Z. F., Xie, J. J., & Oset, E. (2020). Xi(bb) and Omega(bbb) molecular states. Chin. Phys. C, 44(6), 064101–8pp.
Abstract: Using the vector exchange interaction in the local hidden gauge approach, which in the light quark sector generates the chiral Lagrangians and has produced realistic results for Omega(C), Xi(c), Xi(b) and the hidden charm pentaquark states, we study the meson-baryon interactions in the coupled channels that lead to the Xi(bb) and Omega(bbb) excited states of the molecular type. We obtain seven states of the Xi(bb) type with energies between and MeV, and one Omega(bbb) state at MeV.
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