Journal Article

PUBDB-2016-04672

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Heavy quark symmetry and weak decays of the $b$ baryons in pentaquarks with a $c \bar{c}$ component

Ali, A. (Corresponding author)DESY* ; Ahmed, I. ; Aslam, M. J. ; Rehman, A.

2016
Inst. Woodbury, NY

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Please use a persistent id in citations: doi:10.1103/PhysRevD.94.054001

Report No.: DESY-16-102; arXiv:1607.00987

Abstract: The discovery of the baryonic states $P^{+}_{c}$(4380) and $P^{+}_{c}$(4450) by the LHCb collaboration in the process $pp \to b \bar{b} \to \Lambda^{0}_{b}X$, followed by the decay $\Lambda^{0}_{b} \to J/\psi p K^{-}$ has evoked a lot of theoretical interest. These states have the minimal quark content $c \bar{c} uud$, as suggested by their discovery mode $J/\psi p$, and the preferred $J^{P}$ JP assignments are $\frac{5+}{2}$ for the $P^{+}_{c}$(4450) and $\frac{3-}{2}$ for the $P^{+}_{c}$(4380). In the compact pentaquark hypothesis, in which they are interpreted as hidden charm diquark-diquark-antiquark baryons, the assigned spin and angular momentum quantum numbers are $P^{+}_{c}(4380) = {\bar{c}[cu]_{s=1}[ud]_{s=1};L_{\mathscr{P}} = 0,J^{P} = \frac{3-}{2}}$ and$P^{+}_{c}(4450) = {\bar{c}[cu]_{s=1}[ud]_{s=1};L_{\mathscr{P}} = 1,J^{P} = \frac{5+}{2}}$. The subscripts denote the spin of the diquarks and $L_\mathscr{P} = 0, 1$ are the orbital angular momentum quantum numbers of the pentaquarks. We point out that in the heavy quark limit, the spin of the light diquark in heavy baryons becomes a good quantum number, which has consequences for the decay $\Lambda^{0}_{b} \to J/\psi p K^{-}$. With the quantum numbers assigned above for the two pentaquarks, this would allow only the higher mass pentaquark state $P^{+}_{c}(4450)$ having $[ud]_{s=0}$ to be produced in $\Lambda^{0}_{b}$ decays, whereas the lower mass state $P^{+}_{c}(4380)$ having $[ud]_{s=1}$ is disfavored, requiring a different interpretation. Pentaquark spectrum is rich enough to accommodate a $J^{P} = \frac{3-}{2}$ state, which has the correct light diquark spin ${\bar{c}[cu]_{s=1}[ud]_{s=1};L_{\mathscr{P}} = 0,J^{P} = \frac{3-}{2}}$ to be produced in $\Lambda^{0}_{b}$ decays. Assuming that the mass difference between the charmed pentaquarks which differ in the orbital angular momentum $L$ by one unit is similar to the corresponding mass difference in the charmed baryons, $m[\Lambda^{+}_{c}(2625); J^{P} = \frac{3-}{2}] -m[\Lambda^{+}_{c}(2286); J^{P} = \frac{1+}{2}] \simeq 341$ MeV, we estimate the mass of the lower pentaquark $J^{P} = 3/2^{-}$ state to be about 4110 MeV and suggest to reanalyze the LHCb data to search for this third state. Extending these considerations to the pentaquark states having a $c\bar{c}$ pair and three light quarks (u, d, s) in their Fock space, we present the spectroscopy of the S- and P-wave states in an effective Hamiltonian approach. Some of these pentaquarks can be produced in weak decays of the b-baryons. Combining heavy quark symmetry and the SU(3)$_F$ symmetry results in strikingly simple relations among the decay amplitudes which are presented here.

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Contributing Institute(s):

1. Theorie-Gruppe (T)

Research Program(s):

1. 611 - Fundamental Particles and Forces (POF3-611) (POF3-611)

Experiment(s):

1. No specific instrument

Appears in the scientific report 2016

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Database coverage:
; ; ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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Linked articles:

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Preprint/Report Ali, A. (Corresponding author)DESY* ; Ahmed, I. ; Aslam, M. J. ; Rehman, A.
Heavy quark symmetry and weak decays of the $b$-baryons in pentaquarks with a $c\bar{c}$ component
[10.3204/PUBDB-2016-02653]     Files  Fulltext by arXiv.org BibTeX | EndNote: XML, Text | RIS

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