A Caltech Library Service

Form factor counting and HQET matching for new physics in Λ_b → Λ_c*lν

Papucci, Michele and Robinson, Dean J. (2022) Form factor counting and HQET matching for new physics in Λ_b → Λ_c*lν. Physical Review D, 105 (1). Art. No. 016027. ISSN 2470-0010. doi:10.1103/physrevd.105.016027.

[img] PDF - Published Version
Creative Commons Attribution.

[img] PDF - Submitted Version
See Usage Policy.


Use this Persistent URL to link to this item:


We calculate the Λ_b → Λ∗_c(2595)lν and Λ_b → Λ∗_c(2625)lν form factors and decay rates for all possible b→clν̅ four-Fermi interactions in and beyond the Standard Model (SM), including nonzero charged lepton masses and terms up to order O(α_s,1/m_(c,b)) in the heavy quark effective theory (HQET). We point out a subtlety involving the overcompleteness of the representation of the spin-parity 1/2⁺ → 3/2⁻ antisymmetric tensor form factors, relevant also to other higher excited-state transitions, and present a general method for the counting of the physical form factors for any hadronic transition matrix element and their matching onto HQET. We perform a preliminary fit of a simple HQET-based parametrization of the Λ_b → Λ∗_c form factors at O(α_s,1/m_(c,b)) to an existing quark model, providing preliminary predictions for the lepton universality ratios R(Λ∗_c) beyond the SM. Finally, we examine the putative incompatibility of recent lattice QCD results with expectations from the heavy-quark expansion and available experimental data.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Papucci, Michele0000-0003-0810-0017
Additional Information:© 2022 The Author(s). Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3. (Received 5 July 2021; revised 13 October 2021; accepted 1 December 2021; published 27 January 2022) We thank Patrick Owen and Mark Wise for helpful discussions, and Florian Bernlochner, Marat Freytsis, and Zoltan Ligeti for discussions and comments on the manuscript. M. P. is supported by the Walter Burke Institute for Theoretical Physics. D. J. R. is supported in part by the Office of High Energy Physics of the U.S. Department of Energy under Award No. DE-AC02-05CH11231.
Group:Walter Burke Institute for Theoretical Physics
Funding AgencyGrant Number
Walter Burke Institute for Theoretical PhysicsUNSPECIFIED
Department of Energy (DOE)DE-AC02-05CH11231
Issue or Number:1
Record Number:CaltechAUTHORS:20220207-90458000
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:113320
Deposited By: George Porter
Deposited On:08 Feb 2022 16:33
Last Modified:08 Feb 2022 16:33

Repository Staff Only: item control page