Principal investigator: Blaženka Melić
PI's Host institution: Ruđer Bošković Institute
Project duration: 01.02.2020 to 22.07.2024

Project Summary

The lifetimes of heavy hadrons, being the fundamental particle’s property, are obtained by calculating inclusive decays of heavy quarks which are systematically treated in a consistent framework known as the heavy-quark expansion, HQE. Being the bound states of a heavy quark and light constituent (mesons, singly charmed/beauty baryons) or of two heavy quarks and one light constituent (doubly charmed/beauty baryons), heavy hadrons contain soft degrees of freedom which generate nonperturbative power corrections which are difficult to calculate. New experimental data, both on c-hadron decays and on b-decays, have made possible a detailed comparison of experimental and theoretical results and have revealed broad agreement with several notable exceptions: recent measurements of the Ksi(c)+, Ksi(cc)++ and in particular Omega(c)0 lifetimes do not agree with theoretical predictions. Therefore, one has to examine all ingredients of the calculation very carefully and to calculate them very precisely. In particular, the heavy quark mass is not a well defined quantity. The other main source of uncertainty is the value of the heavy hadron wave function which parametrizes the contribution of dimension-6 operators and higher and leads to the main differences in the lifetimes. The uncertainties beyond these “natural uncertainties” are considered to be violations of quark-hadron duality. Since the inverse beauty quark mass appears to be a good expansion parameter in beauty decays the charmed hadron decays are left as a playground for studying and testing of the possible violation of the quark-hadron duality. However, to be able to understand the complexity of baryonic wave functions, the beauty baryon decays can provide valuable information too. Due to the all facts said above, it is timely to revisit the calculation of the heavy hadron lifetimes and to establish the reliable methods and models used in the calculation.


Principal investigator

Blaženka Melić

RBI, Croatia


Ivan Nisandzic

RBI, Croatia


Arslan Sikandar

RBI, Croatia

PhD students

Lovro Dulibic

RBI, Croatia

Former members

Oleg Antipin

associate, RBI, Croatia

James Gratrex

postdoc, RBI, Croatia

Domagoj Leljak

PhD student, RBI, Croatia

List of publications

1. The DDπ and BBπ couplings from light-cone sum rules

A. Khodjamirian, B. Melic, Y-M Wang, Y-B Wei
Journal of High Energy Physics (JHEP) 03 (2021) 016

2. The B → π form factors from QCD and their impact on |Vub|

D. Leljak, B. Melić, D. van Dyk
Journal of High Energy Physics (JHEP) 07 (2021) 036

3. EOS: a software for flavor physics phenomenology

EOS Authors Collaboration, Danny van Dyk et al. (D. Leljak)
The European Physical Journal C 82 (2022) 6, 569

4. Lifetimes of singly charmed hadrons

J. Gratrex, B. Melić, I. Nišandžić
Journal of High Energy Physics (JHEP) 07 (2022) 058

5. The analytic structure of the fixed charge expansion

O. Antipin, J. Bersini, F. Sanino, M. Torres
Journal of High Energy Physics (JHEP) 06 (2022) 041

6. Quark-hadron duality at work: lifetimes of bottom baryons

James Gratrex, Alexander Lenz, Blazenka Melic, Ivan Nisandzic, Maria-Laura Piscopo, Alexey Rusov
Journal of High Energy Physics (JHEP) 04 (2023) 034

7. Charmed hadron lifetimes

J. Gratrex, B. Melic, I. Nisandzic
Proceedings of 22th Hellenic School and Workshops on Elementary Particle Physics and Gravity (CORFU2022), 28 August-1 October 2022, Corfu, Greece

8. Toward a complete description of b→uℓν decays within the Weak Effective Theory

D. Leljak, B. Melic, F. Novak, M. Rebould, D. van Dyk
Journal of High Energy Physics (JHEP) 08 (2023) 063

9. Revisiting lifetimes of doubly charmed baryons

L. Dulibic, J. Gratrex, B. Melic, I. Nisandzic
Journal of High Energy Physics (JHEP) 07 (2023) 061

10. A guide to the QCD light-cone sum rules for b-quark decays

A. Khodjamirian, B. Melic, Y-M Wang
Invited review for Eur.Phys.J Spec.Top.; Special Issue: "b-quark physics as a precision laboratory: status and future prospects", EPJ ST (2023) arXiv:??

Talks and Seminars

Oleg Antipin, "Scaling dimensions of fixed charge operators", invited talk, Portorož 2021: Physics of the Flavourful Universe, 21-24.09.2021. Portorož, Slovenia

Blaženka Melić, "Exclusive Vub determination from QCD - solution to Vub puzzle?", invited talk, Portorož 2021: Physics of the Flavourful Universe, 21-24.09.2021. Portorož, Slovenia

James Gratrex, "Lifetimes of singly charmed hadrons", talk, 09.06.2022, Lanzhou University (online)

James Gratrex, "Lifetimes of singly charmed hadrons", talk, 16.06.2022, Quirks 2022: Quirks in Quark Flavour Physics 14-17.06.2022, Zadar, Croatia

Blaženka Melić, "Revisiting puzzles in lifetimes of single charmed hadron", invited plenary talk, 9th Workshop on Flavour Symmetries and Consequences in Accelerators and Cosmology, 27.06.2022 - 01.07.2022, IST, Lisbon, Portugal

Blaženka Melić, "Charm lifetimes", invited talk, 31.8.2022, Corfu2022 Workshop on the Standard Model and Beyond, 28.08.2022 - 08.09.2022, Mon Repos, Corfu, Greece

James Gratrex, "Lifetimes of singly charmed hadrons", talk, 25.10.2022, Siegen Universität, Siegen, Germany

Ivan Nisandzic, "Lifetimes of heavy baryons", invited talk, 11.04.2023, Portoroz 2023: Particle Physics from Early Universe to Future Colliders, 10-14.4.2023, Portoroz, Slovenia

Blaženka Melić, "Heavy Hadron Lifetimes", seminar, 24.04.2023, Ludwig-Maximilians-Universität München, Germany

Blaženka Melić, "Charm Hadron Lifetimes and the status of D-Dbar mixing", invited plenary talk, 17.7.2023, 11th International workshop on Charm Physics (CHARM 2023), 17-21.07.2023, Siegen, Germany

Blaženka Melić, "|Vub| and the potential impact of new physics in exclusive b -> u l nu decays ", invited talk, 20.09.2023, 12th International workshop on the CKM Unitarity Triangle (CKM 2023), 18-22.09.2023, Santiago de Compostela, Spain



9-21 July 2023: Methods of Effective Field Theory and Lattice Field Theory Bad Honnef Physics School (L. Dulibić)

22-31 August 2023: 2023 CERN-Fermilab HCP Summer School (L. Dulibić)

5-15 September 2023: 54. Herbstschule für Hochenergiephysik 2023 (L. Dulibić)


Research Visits

24-30 October 2022: visit at University of Siegen (I. Nisandzic and J. Gratrex).

24-25 April 2023: visit at LMU, Munich (B. Melic).


Event Organization

Quirks 2022: Quirks in Quark Flavour Physics, 14.06.2022 - 17.06.2022, Zadar, Croatia
Chair: Blaženka Melić


Dissemination and Outreach



Postgraduate course "Elementary particle physics" at University of Zagreb (B. Melić)

Postgraduate course "Effective field theories" at University of Zagreb (B. Melić)

Domagoj Leljak, PhD defense 15.7.2021, "Testing the standard model in heavy quark decays", PhD thesis, supervisor: dr. Blaženka Melić

Eugen Hukić, master defense 4.3.2022, "Raspadi i vremena zivota teskih hadrona", master thesis, supervisor: dr. Blaženka Melić

Ivan Vujmilović, master defense 5.7.2023, "Elektroslabe interakcije u efektivnoj teoriji polja", master thesis, supervisor: dr.Ivan Nisandzic


Blaženka Melić

Phone: +385 1 456 1033
Ruđer Bošković Institute
Bijenička cesta 54
10000 Zagreb, Croatia