### Abstract

We address the numerical aspects of local quark-hadron duality using the example of the exactly solvable 't Hooft model, two-dimensional QCD with N_{c}→∞. The primary focus of these studies is the total semileptonic decay widths relevant for extracting |V_{cb}| and |V_{ub}|. We compare the exact channel-by-channel sum of exclusive modes to the corresponding rates obtained in the standard 1/m_{Q} expansion arising from the operator product expansion. An impressive agreement sets in unexpectedly early, immediately after the threshold for the first hadronic excitation in the final state. Yet even at higher energy release it is possible to discern the seeds of duality-violating oscillations. We find the "small velocity" sum rules to be exceptionally well saturated already by the first excited state. We also obtain a convincing degree of duality in the differential distributions and in an analogue of R_{e+e-}(s). Finally, we discuss possible lessons for semileptonic decays of actual heavy quarks in QCD.

Original language | English (US) |
---|---|

Article number | 094011 |

Pages (from-to) | 1-21 |

Number of pages | 21 |

Journal | Physical Review D - Particles, Fields, Gravitation and Cosmology |

Volume | 62 |

Issue number | 9 |

State | Published - Nov 1 2000 |

Externally published | Yes |

### Fingerprint

### ASJC Scopus subject areas

- Physics and Astronomy(all)
- Nuclear and High Energy Physics
- Mathematical Physics
- Physics and Astronomy (miscellaneous)

### Cite this

*Physical Review D - Particles, Fields, Gravitation and Cosmology*,

*62*(9), 1-21. [094011].

**Precision studies of duality in the 't Hooft model.** / Lebed, Richard; Uraltsev, Nikolai G.

Research output: Contribution to journal › Article

*Physical Review D - Particles, Fields, Gravitation and Cosmology*, vol. 62, no. 9, 094011, pp. 1-21.

}

TY - JOUR

T1 - Precision studies of duality in the 't Hooft model

AU - Lebed, Richard

AU - Uraltsev, Nikolai G.

PY - 2000/11/1

Y1 - 2000/11/1

N2 - We address the numerical aspects of local quark-hadron duality using the example of the exactly solvable 't Hooft model, two-dimensional QCD with Nc→∞. The primary focus of these studies is the total semileptonic decay widths relevant for extracting |Vcb| and |Vub|. We compare the exact channel-by-channel sum of exclusive modes to the corresponding rates obtained in the standard 1/mQ expansion arising from the operator product expansion. An impressive agreement sets in unexpectedly early, immediately after the threshold for the first hadronic excitation in the final state. Yet even at higher energy release it is possible to discern the seeds of duality-violating oscillations. We find the "small velocity" sum rules to be exceptionally well saturated already by the first excited state. We also obtain a convincing degree of duality in the differential distributions and in an analogue of Re+e-(s). Finally, we discuss possible lessons for semileptonic decays of actual heavy quarks in QCD.

AB - We address the numerical aspects of local quark-hadron duality using the example of the exactly solvable 't Hooft model, two-dimensional QCD with Nc→∞. The primary focus of these studies is the total semileptonic decay widths relevant for extracting |Vcb| and |Vub|. We compare the exact channel-by-channel sum of exclusive modes to the corresponding rates obtained in the standard 1/mQ expansion arising from the operator product expansion. An impressive agreement sets in unexpectedly early, immediately after the threshold for the first hadronic excitation in the final state. Yet even at higher energy release it is possible to discern the seeds of duality-violating oscillations. We find the "small velocity" sum rules to be exceptionally well saturated already by the first excited state. We also obtain a convincing degree of duality in the differential distributions and in an analogue of Re+e-(s). Finally, we discuss possible lessons for semileptonic decays of actual heavy quarks in QCD.

UR - http://www.scopus.com/inward/record.url?scp=17044424550&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=17044424550&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:17044424550

VL - 62

SP - 1

EP - 21

JO - Physical review D: Particles and fields

JF - Physical review D: Particles and fields

SN - 1550-7998

IS - 9

M1 - 094011

ER -