A recent analysis by the LHCb collaboration suggests the existence of three narrow pentaquark-like states -the P c (4312), P c (4440) and P c (4457) -instead of just one in the previous analysis (the P c (4450)). The closeness of the P c (4312) to theDΣ c threshold and the P c (4440)/P c (4457) to theD * Σ c one suggests a molecular interpretation of these resonances. We show that these three pentaquark-like resonances can be naturally accommodated in a contact-range effective field theory description that incorporates heavy-quark spin symmetry. This description leads to the prediction of all the seven possible S-wave heavy antimeson-baryon molecules (that is, there should be four additional molecular pentaquarks in addition to the P c (4312), P c (4440) and P c (4457)), providing the first example of a heavy-quark spin symmetry molecular multiplet that is complete. If this is confirmed, it will not only give us an impressive example of the application of heavy-quark symmetries and effective field theories in hadron physics: it will also uncover a clear and powerful ordering principle for the molecular spectrum, reminiscent of the SU(3)-flavor multiplets to which the light hadron spectrum conforms.
The χ(b)(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider at sqrt[s] = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb(-1), these states are reconstructed through their radiative decays to Υ(1S,2S) with Υ → μ+ μ-. In addition to the mass peaks corresponding to the decay modes χ(b)(1P,2P) → Υ(1S)γ, a new structure centered at a mass of 10.530 ± 0.005(stat) ± 0.009(syst) GeV is also observed, in both the Υ(1S)γ and Υ(2S)γ decay modes. This structure is interpreted as the χ(b)(3P) system.
Using 230 Â 10 6 B " B events recorded with the BABAR detector at the e þ e À storage rings PEP-II, we reconstruct approximately 4100 B 0 ! J= K þ % À and 9930 B þ ! J= K þ decays with J= ! " þ " À and e þ e À . From the measured B-momentum distributions in the e þ e À rest frame, we determine the mass difference mðB 0 Þ À mðB þ Þ ¼ ðþ0:33 AE 0:05 AE 0:03Þ MeV=c 2 .
In a search for B-->cc[over ]gammaK decays with the BABAR detector, where cc[over ] includes J/psi and psi(2S), and K includes K(+/-), K(S)(0), and K(*)(892), we find evidence for X(3872)-->J/psigamma and X(3872)-->psi(2S)gamma with 3.6sigma and 3.5sigma significance, respectively. We measure the product of branching fractions B(B(+/-)-->X(3872)K(+/-))xB(X(3872)-->J/psigamma)=[2.8+/-0.8(stat)+/-0.1(syst)]x10(-6) and B(B(+/-)-->X(3872)K(+/-))xB(X(3872)-->psi(2S)gamma)=[9.5+/-2.7(stat)+/-0.6(syst)]x10(-6).
We present a study of the decays B 0,+ → J/ψπ + π − π 0 K 0,+ , using 467×10 6 B B pairs recorded with the BABAR detector. We present evidence for the decay mode X(3872) → J/ψω, with product branching fractions B(B + → X(3872A detailed study of the π + π − π 0 mass distribution from X(3872) decay favors a negative-parity assignment.
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