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Register a new userMagnetic Moments of $J^P={3/2}^+$ Pentaquarks
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If the $J^P$ of $Theta_5^+$ and $Xi_5^{--}$ pentaquarks is really found to be ${1over 2}^+$ by future experiments, they will be accompanied by $J^P={3over 2}^+$ partners in some models. It is reasonable to expect that these $J^P={3over 2}^+$ states will also be discovered in the near future with the current intensive experimental and theoretical efforts. We estimate $J^P={3/2}^+$ pentaquark magnetic moments using different models.
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If Jaffe and Wilczeks diquark picture for $Theta_5$ pentaquark is correct, there should also exist a $SU_F$(3) pentaquark octet and singlet with no orbital excitation between the diquark pair, hence $J^P={1/2}^-$. These states are lighter than the $Theta_5$ anti-decuplet and lie close to the orbitally excited (L=1) three-quark states in the conventional quark model. We calculate their masses and magnetic moments and discuss their possible strong decays using the chiral Lagrangian formalism. Among them two pentaquarks with nucleon quantum numbers may be narrow. Selection rules of strong decays are derived. We propose the experimental search of these nine additional $J^P={1/2}^-$ baryon states. Especially there are two additional $J^P={1/2}^-$ $Lambda$ baryons around $Lambda (1405)$. We also discuss the interesting possibility of interpreting $Lambda (1405)$ as a pentaquark. The presence of these additional states will provide strong support of the diquark picture for the pentaquarks. If future experimental searches fail, one has to re-evaluate the relevance of this picture for the pentaquarks.
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.
We show that a unified framework based on an $SU(2)_H$ horizontal symmetry which generates a naturally large neutrino transition magnetic moment and explains the XENON1T electron recoil excess also predicts a positive shift in the muon anomalous magnetic moment. This shift is of the right magnitude to be consistent with the Brookhaven measurement as well as the recent Fermilab measurement of the muon $g-2$. A relatively light neutral scalar from a Higgs doublet with mass near 100 GeV contributes to muon $g-2$, while its charged partner induces the neutrino magnetic moment. We analyze the collider tests of this framework and find that the HL-LHC can probe the entire parameter space of these models.
The magnetic moments of the low lying, negative parity, spin-3/2 baryons are calculated within the light cone QCD sum rules method. The contributions coming from the positive parity, spin-3/2 baryons, as well as from the positive and negative parity spin-1/2 baryons are eliminated by constructing combinations of various invariant amplitudes corresponding to the coefficients of the different Lorentz structures.
The chiral corrections to the magnetic moments of the spin-$frac{1}{2}$ doubly charmed baryons are systematically investigated up to next-to-next-to-leading order with heavy baryon chiral perturbation theory (HBChPT). The numerical results are calculated up to next-to-leading order: $mu_{Xi^{++}_{cc}}=-0.25mu_{N}$, $mu_{Xi^{+}_{cc}}=0.85mu_{N}$, $mu_{Omega^{+}_{cc}}=0.78mu_{N}$. We also calculate the magnetic moments of the other doubly heavy baryons, including the doubly bottomed baryons (bbq) and the doubly heavy baryons containing a light quark, a charm quark and a bottom quark (${bc}q$ and $[bc]q$): $mu_{Xi^{0}_{bb}}=-0.84mu_{N}$, $mu_{Xi^{-}_{bb}}=0.26mu_{N}$, $mu_{Omega^{-}_{bb}}=0.19mu_{N}$, $mu_{Xi^{+}_{{bc}q}}=-0.54mu_{N}$, $mu_{Xi^{0}_{{bc}q}}=0.56mu_{N}$, $mu_{Omega^{0}_{{bc}q}}=0.49mu_{N}$, $mu_{Xi^{+}_{[bc]q}}=0.69mu_{N}$, $mu_{Xi^{0}_{[bc]q}}=-0.59mu_{N}$, $mu_{Omega^{0}_{[bc]q}}=0.24mu_{N}$.
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