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Towards the LHCb pentaquark modes in the single-charm sector

Chao-Wei Shen, Yong-Hui Lin, Hao-Jie Jing

TL;DR

The paper addresses the Λ_c spectrum and its relation to the LHCb pentaquarks by analyzing $DN$-$D^*N$ dynamics with two complementary frameworks: a heavy-quark effective theory (HQET) short-range EFT with two leading contact terms $C_0$ and $C_1$, and a flavor-SU(4) constrained one-boson-exchange model. Both approaches yield a consistent near-threshold molecular interpretation: $\Lambda_c(2765)$ as a $DN$ bound state with $J^P=1/2^-$, and $\Lambda_c(2910)$ and $\Lambda_c(2940)$ as $D^*N$ bound states with $J^P=1/2^-$ and $3/2^-$, mirroring the hidden-charm states $P_{c\bar{c}}(4312)$, $P_{c\bar{c}}(4440)$, and $P_{c\bar{c}}(4457)$. A favored $J^P=3/2^-$ assignment for $\Lambda_c(2940)$ aligns with a $3/2^-$ $D^*N$ configuration for $P_{c\bar{c}}(4457)$, supporting cross-flavor correlations and suggesting a universal near-threshold molecular formation mechanism across open- and hidden-heavy-quark sectors. The work highlights the potential for cross-flavor insights to resolve the quantum numbers of experimentally undetermined pentaquark states and guides future experimental tests. These findings imply that similar near-threshold molecular structures may arise in single-heavy-quark systems as well.

Abstract

The mass spectrum of $Λ_c$ baryon family is investigated within the $DN$-$D^*N$ coupled-channel framework using two phenomenological approaches for the low-energy $D^{(*)} N$ interactions: the heavy quark effective theory and the flavor-symmetry-constrained effective Lagrangian method. It is shown that the LHCb pentaquark states have direct analogs in the $Λ_c$ family. Specifically, $Λ_c(2765)$, $Λ_c(2910)$, and $Λ_c(2940)$ mirror the patterns of $P_{c\bar{c}}(4312)$, $P_{c\bar{c}}(4440)$, and $P_{c\bar{c}}(4457)$, respectively. These mirror pentaquark modes offer valuable insights into the quantum numbers of the two heavy $P_{c\bar{c}}$ states, which remain experimentally undetermined. Further exploration of such correlations among exotic hadronic states across different flavor sectors will be crucial for developing a comprehensive theoretical understanding of the modern hadron spectrum.

Towards the LHCb pentaquark modes in the single-charm sector

TL;DR

The paper addresses the Λ_c spectrum and its relation to the LHCb pentaquarks by analyzing - dynamics with two complementary frameworks: a heavy-quark effective theory (HQET) short-range EFT with two leading contact terms and , and a flavor-SU(4) constrained one-boson-exchange model. Both approaches yield a consistent near-threshold molecular interpretation: as a bound state with , and and as bound states with and , mirroring the hidden-charm states , , and . A favored assignment for aligns with a configuration for , supporting cross-flavor correlations and suggesting a universal near-threshold molecular formation mechanism across open- and hidden-heavy-quark sectors. The work highlights the potential for cross-flavor insights to resolve the quantum numbers of experimentally undetermined pentaquark states and guides future experimental tests. These findings imply that similar near-threshold molecular structures may arise in single-heavy-quark systems as well.

Abstract

The mass spectrum of baryon family is investigated within the - coupled-channel framework using two phenomenological approaches for the low-energy interactions: the heavy quark effective theory and the flavor-symmetry-constrained effective Lagrangian method. It is shown that the LHCb pentaquark states have direct analogs in the family. Specifically, , , and mirror the patterns of , , and , respectively. These mirror pentaquark modes offer valuable insights into the quantum numbers of the two heavy states, which remain experimentally undetermined. Further exploration of such correlations among exotic hadronic states across different flavor sectors will be crucial for developing a comprehensive theoretical understanding of the modern hadron spectrum.

Paper Structure

This paper contains 5 sections, 12 equations, 1 figure, 2 tables.

Table of Contents

  1. Introduction
  2. $DN$-$D^*N$ system in the heavy quark effective theory
  3. $DN$-$D^*N$ system in the effective Lagrangian method
  4. Conclusion and outlook
  5. Potentials and Couplings

Figures (1)

  • Figure 1: The distribution of pole positions obtained from 5000 different parameter samples. Colors indicate the density of the poles, with warmer colors representing higher densities. The two red dashed lines mark the $DN$ and $D^*N$ thresholds, while the green bars show the measured masses of $\Lambda_c(2765)$, $\Lambda_c(2910)$ and $\Lambda_c(2940)$ along with their experimental uncertainties.