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Flavour anomalies and matter-antimatter asymmetry in b-baryon decays

English title Flavour anomalies and matter-antimatter asymmetry in b-baryon decays
Applicant Silva Coutinho Rafael
Number 174182
Funding scheme Ambizione
Research institution Physik-Institut Universität Zürich
Institution of higher education University of Zurich - ZH
Main discipline Particle Physics
Start/End 01.09.2017 - 31.08.2021
Approved amount 788'913.00
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Keywords (6)

Flavour Physics; Particle Physics; CP violation; Rare B decays; LHC; LHCb

Lay Summary (Italian)

Lead
I decadimenti adronici con "beauty" e semileptonici rari sono fra i campi più promettenti per la ricerca di estensioni del Modello Standard, indicate anche come "Nuova Fisica". Nel mio progetto propongo dei nuovi metodi per confermare, in maniera indipendente e complementare, le anomalie osservate dalla collaborazione LHCb nel settore della fisica del "flavour" e fornisco delle misure ausiliari che permetteranno di ridurre le incertezze teoriche ora presenti.
Lay summary
2. Piano di ricerca

Recenti studi dei decadimenti semileptonici rari dei mesoni con "beauty" mostrano delle interessanti discrepanze  con il Modello Standard (MS). Malgrado la significatività di tali risultati non risulti essere ancora conclusiva,  è fondamentale utilizzare dei nuovi approcci per confermare  indipendentemente le attuali anomalie. In questo progetto mi prefiggo di attuare delle nuove misure che permetteranno di rivelare senza ambiguità la natura delle anomalie del "flavour".

La ricerca di violazione CP nei decadimenti dei barioni  con "beauty" è diventato sperimentalmente accessibile solo di recente in LHCb. Questo fenomeno è legato all'asimmetria materia-antimateria nell'universo e la sua osservazione nel settore barionico aprirebbe un nuovo campo di esplorazione nel MS. Grazie ai dati raccolti da LHCb nel primo e secondo run del LHC, studierò i canali più sensibili per questo effetto con un grande potenziale di scoperta.

3.Contesto scientifico e sociale

Il progetto  si propone di trovare delle prove a conferma dell'esistenza di nuovi fenomeni nella fisica dei quark con "flavour" o di porre dei limiti stringenti sul loro effetto nel MS. Questi risultati chiariranno il comportamento della Nuova Fisica e potrebbero pertanto rivoluzionare l'attuale comprensione  delle interazioni fisiche a breve distanza.
Direct link to Lay Summary Last update: 24.08.2017

Lay Summary (English)

Lead
Rare semileptonic and hadronic beauty decays provide some of the most promising framework to search for extensions of the Standard Model of particle physics, also referred to as "New Physics". In my project, I propose novel approaches to independently and complementary confirm the present anomalies observed by the LHCb collaboration in the flavour physics sector and, provide crucial auxiliary measurements which will allow to reduce the existing theoretical uncertainties.
Lay summary

2. Research plan

Recent studies of rare semileptonic decays of beauty mesons reported some intriguing discrepancies with the Standard Model (SM). Whilst the level of significance of these results are not conclusive yet, novel approaches to independently and complementary confirm the present anomalies are paramount. In this research I will pursuit new measurements that can reveal unambiguously the existence of New Physics (NP) and the nature of these flavour anomalies.

Searches for CP violation in decays of beauty baryons became experimentally accessible only recently with LHCb. This phenomenon is related to the matter-antimatter asymmetry of the Universe, and its observation in the baryonic sector would open a new field of exploration and provide new probes for the SM. With the unprecedented LHCb dataset collected in the first and second runs of the LHC, I aim to study the most sensitive channel for this effect with a great discovery potential. 

3. Scientific and societal context

I expect with this research to either find evidence for new phenomena in quark flavour physics, or to place stringent bounds on the size of any NP effects. These results will yield insight as to how NP behaves, and could therefore revolutionise our understanding of physics interaction at the smallest distances. 

Direct link to Lay Summary Last update: 24.08.2017

Responsible applicant and co-applicants

Employees

Publications

Publication
zfit: Scalable pythonic fitting
Eschle Jonas, Puig Navarro Albert, Silva Coutinho Rafael, Serra Nicola (2020), zfit: Scalable pythonic fitting, in SoftwareX, 11, 100508-100508.
Measurement of CP violation in the Bs → ϕϕ decay and search for the B0 → ϕϕ decay
Aaij R., Abellán Beteta C., Adeva B., Adinolfi M., Aidala C. A., Ajaltouni Z., Akar S., Albicocco P., Albrecht J., Alessio F., Alexander M., Alfonso Albero A., Alkhazov G., Alvarez Cartelle P., Alves A. A., Amato S., Amhis Y., An L., Anderlini L., Andreassi G., Andreotti M., Andrews J. E., Archilli F., Arnau Romeu J., et al. (2019), Measurement of CP violation in the Bs → ϕϕ decay and search for the B0 → ϕϕ decay, in Journal of High Energy Physics, 2019(12), 155-155.
Amplitude analysis of B s 0 → K S 0 K±π∓ decays
Aaij R., Abellán Beteta C., Adeva B., Adinolfi M., Aidala C. A., Ajaltouni Z., Akar S., Albicocco P., Albrecht J., Alessio F., Alexander M., Alfonso Albero A., Alkhazov G., Alvarez Cartelle P., Alves A. A., Amato S., Amerio S., Amhis Y., An L., Anderlini L., Andreassi G., Andreotti M., Andrews J. E., Archilli F., et al. (2019), Amplitude analysis of B s 0 → K S 0 K±π∓ decays, in Journal of High Energy Physics, 2019(6), 114-114.
Towards establishing lepton flavor universality violation in B→K*ℓ+ℓ− decays
Mauri Andrea, Serra Nicola, Silva Coutinho Rafael (2019), Towards establishing lepton flavor universality violation in B→K*ℓ+ℓ− decays, in Physical Review D, 99(1), 013007-013007.
Prospects for disentangling long- and short-distance effects in the decays B→K*μμ
ChrzaszczMarcin, MauriAndrea, SerraNicola, Silva CoutinhoRafael, van DykDanny (2019), Prospects for disentangling long- and short-distance effects in the decays B→K*μμ, in JHEP , 20, 236.
Laura ++ : A Dalitz plot fitter
Back John, Gershon Tim, Harrison Paul, Latham Thomas, O’Hanlon Daniel, Qian Wenbin, del Amo Sanchez Pablo, Craik Daniel, Ilic Jelena, Otalora Goicochea Juan Martin, Puccio Eugenia, Silva Coutinho Rafael, Whitehead Mark (2018), Laura ++ : A Dalitz plot fitter, in Computer Physics Communications, 231, 198-242.
Amplitude Analysis of the Decay B0 → KS0π+π− and First Observation of the CP Asymmetry in B0→K*(892)−π+
Aaij R., Adeva B., Adinolfi M., Ajaltouni Z., Akar S., Albrecht J., Alessio F., Alexander M., Alfonso Albero A., Ali S., Alkhazov G., Alvarez Cartelle P., Alves A. A., Amato S., Amerio S., Amhis Y., An L., Anderlini L., Andreassi G., Andreotti M., Andrews J. E., Appleby R. B., Archilli F., d’Argent P., et al. (2018), Amplitude Analysis of the Decay B0 → KS0π+π− and First Observation of the CP Asymmetry in B0→K*(892)−π+, in Physical Review Letters, 120(26), 261801-261801.
Updated branching fraction measurements of B(s)0 → KS0h+h′− decays
Aaij R., Adeva B., Adinolfi M., Ajaltouni Z., Akar S., Albrecht J., Alessio F., Alexander M., Ali S., Alkhazov G., Alvarez Cartelle P., Alves A. A., Amato S., Amerio S., Amhis Y., An L., Anderlini L., Andreassi G., Andreotti M., Andrews J. E., Appleby R. B., Archilli F., d’Argent P., Arnau Romeu J., et al. (2017), Updated branching fraction measurements of B(s)0 → KS0h+h′− decays, in Journal of High Energy Physics, 2017(11), 27-27.

Collaboration

Group / person Country
Types of collaboration
CERN Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Particles and Nuclei International Conference (PANIC) Talk given at a conference Flavour physics with rare, electroweak-penguin, and semileptonic decays at LHCb 05.09.2021 Lisbon (remote), Portugal Wang Zhenzi;
SPS/CHIPP Annual meeting 2021 Talk given at a conference Angular analysis of B → K*ee decays at LHCb 30.08.2021 Innsbruck, Austria Wang Zhenzi;
SPS/CHIPP Annual meeting 2021 Talk given at a conference A new approach in the search for New Physics in b→sl+l- decays 30.08.2021 Innsbruck, Austria Atzeni Michele;
Beyond the Flavour Anomalies workshop Talk given at a conference Experimental challenges for future angular and amplitude measurements 01.04.2020 Durham (remote), Great Britain and Northern Ireland Silva Coutinho Rafael;
MIAMI 2019 Talk given at a conference Overview of recents results from LHCb 12.12.2019 Fort Lauderdale, United States of America Silva Coutinho Rafael;
International Workshop on Baryon and Lepton Number Violation (BLV2019) Talk given at a conference LFV, lepton universality, and rare decay searches at the LHC 21.10.2019 Madri, Spain Wang Zhenzi;
b → sℓℓ: 7th Workshop on Rare Semileptonic B Decays Talk given at a conference Experimental approaches to disentangle long-distance contributions to b → s l+l- 04.09.2019 Lyon, France Silva Coutinho Rafael;
SPS/CHIPP Annual meeting 2019 Talk given at a conference Angular analysis of B → K* l+l- decays at LHCb 26.08.2019 Zurich, Switzerland Wang Zhenzi;
Heavy-Quark Physics and Fundamental Symmetries [INT-19-2b] Talk given at a conference Is it possible to claim NP on amplitude analyses of b → s l+l- decays alone? [An experimentalist view] 19.08.2019 Seattle, United States of America Silva Coutinho Rafael;
47th SLAC Summer Institute: Menu of Flavors: Quarks, Charged Leptons & Neutrinos Individual talk Highlights from LHCb 12.08.2019 Stanford, California, United States of America Silva Coutinho Rafael;
Amplitude analysis for flavour anomalies Talk given at a conference Prospects for DD+long-lived particle at LHCb 04.07.2019 Bristol, Great Britain and Northern Ireland Silva Coutinho Rafael;
LHC Seminar Individual talk Amplitude analyses of multibody hadronic decays at LHCb 11.12.2018 Cern, Geneva, Switzerland Silva Coutinho Rafael;
SPS/CHIPP Annual meeting 2018 Talk given at a conference Anatomy of B0 → K*0μ+μ− decays and prospects for NP 29.08.2018 Lausanne, Switzerland Mauri Andrea;
SPS/CHIPP Annual meeting 2018 Poster Angular Analysis of B0 → K*0e+e− Decays at LHCb 29.08.2018 Lausanne, Switzerland Wang Zhenzi;
ICHEP 2018 Talk given at a conference Towards establishing New Physics in B0→K∗0ℓ+ℓ− decays 04.07.2018 Seoul, Korean Republic (South Korea) Mauri Andrea;
Workshop on multibody charmless B-hadron decays Talk given at a conference Amplitude analysis of Bs → KSKpi decays 06.06.2018 Paris, France Silva Coutinho Rafael;
International Conference on B-Physics at Frontier Machines, BEAUTY Talk given at a conference Charmless multi-body b decays at LHCb 06.05.2018 Elba, Italy Silva Coutinho Rafael;
Towards the Ultimate Precision in Flavour Physics Talk given at a conference Limiting factors for tests of LFU in neutral-current semi-leptonic decays 16.04.2018 Warwick, Great Britain and Northern Ireland Silva Coutinho Rafael;
b → sℓℓ: 6th Workshop on Rare Semileptonic B Decays Talk given at a conference Reconstructing final states with electrons at LHCb and interplay with QED corrections 20.02.2018 Munich, Germany Silva Coutinho Rafael;
b → sℓℓ: 6th Workshop on Rare Semileptonic B Decays Talk given at a conference Direct measurements of Wilson coefficients and LFU test in B → K*ll decay 20.02.2018 Munich, Germany Mauri Andrea;
b → sℓℓ: 6th Workshop on Rare Semileptonic B Decays Talk given at a conference Prospects for data-driven determination of hadronic matrix element in B → K*µµ decay 20.02.2018 Munich, Germany Mauri Andrea;
Pion-Kaon Interactions Workshop Talk given at a conference Non-leptonic three body decays at LHCb 14.02.2018 Newport News, United States of America Silva Coutinho Rafael;
Joint-BESIII-LHCb-Workshop Talk given at a conference Disentangling charmonia in the threshold region 08.02.2018 Beijing, China Silva Coutinho Rafael;
XXV EPIPHANY Conference on advances Heavy Ion physics Talk given at a conference Heavy flavour physics at LHCb 08.01.2018 Cracow, Poland Silva Coutinho Rafael;
Implications of LHCb measurements and future prospects Talk given at a conference Prospects for model-independent data-driven analyses of the decay B → K∗μμ 08.11.2017 Geneva, Switzerland Mauri Andrea;


Communication with the public

Communication Title Media Place Year
New media (web, blogs, podcasts, news feeds etc.) Flavour at Zurich Youtube channel International 2018

Abstract

The discovery of the long-awaited Higgs boson at the Large Hadron Collider (LHC) confirms the remarkable success of the Standard Model (SM) of particle physics. While in the last decades high-energy experiments have verified to an impressive level of accuracy the predictions of the SM, the theory is not complete, and it does not provide explanations for dark matter, neutrino oscillation or the baryogenesis. A number of extensions of the SM have been proposed (e.g. the existence of new massive particles), and direct searches for New Physics (NP) effects are currently the dominant experimental effort of the particle physics community. Since not clear sign of NP has been seen, indirect searches, which are highly sensitive to new particles effects at higher scales and new couplings, are becoming of crucial importance. In particular, stringent constraints in the phase space of NP contributions have been placed in a series of important observables. A prime example is the heavy flavour physics programme that studies interactions that differ among flavours, mainly in decays involving c and b quarks. This term has been firstly introduced by Murray Gell-Mann and his student, when noting that "just as ice-cream has both colour and flavour so do quarks" (and leptons). In the SM, flavour-physics refers to the weak and Yukawa interactions, and NP could introduce additional flavoured interactions. There are two main motivations for ongoing experimental investigations into this field: search for rare or SM forbidden processes beyond the current energy frontier; and CP violation and its connection to the matter-antimatter asymmetry of the Universe. My proposed project aims to improve the understanding of rare semileptonic and hadronic b-hadron decays, by addressing both of the aforementioned key measurements: flavour anomalies in b -> s l+ l- transitions that could be a genuine sign of NP and CP violation in b baryons. Recent studies of rare semileptonic decays of beauty mesons, mediated through virtual quantum loops, reported some intriguing discrepancies with the SM predictions, which seems to form a coherent pattern. In particular, in the angular observables P'5 of the B0 -> K*0 mu+ mu- decay and the suppression of the muon channel in the ratio of branching fractions of B+ -> K+ mu+ mu- to B+ -> K+ e+ e- transitions. In order to achieve a conclusive understanding of these anomalies, a close collaboration between theory and experiment, with novel approaches that include all of the information that is relevant for the theory calculations is paramount. The proposed research will, for the first time, disentangle hadronic long-distance effects from NP contributions, that currently limit the unambiguous claim of existence of physics beyond the SM. In addition, the nature of the flavour anomalies, mainly its connection with the hypothesis that particles couple unequally to different flavours of leptons, will be finally completely elucidated. Searches for CP violation in decays of beauty baryons to purely hadronic final states became experimentally accessible only recently with the start of LHCb. First asymmetry measurements in multi-body charmless decays have been carried out by me and no significant CP violation has been observed. More recently, a first evidence of this phenomena in Lb -> p pi- pi+ pi- has been reported by LHCb. This has an extraordinary impact to the field and further measurements with other multi-body beauty baryon decays are compulsory to confirm such observation. In this project, the golden channel Lb -> p K*- is studied in a Dalitz-plot analysis of the decay Lb -> K0 p pi-. This has a great potential to make the first observation of CP violation in b baryons and also provide deeper insights on the dynamics of these processes. Ultimately, I expect with this research to either find evidence for new phenomena in quark flavour physics, or to place stringent bounds on the size of any NP effects, using the unprecedented LHCb dataset available in Run-I and II. Regardless of the outcome, my results will yield insight as to how NP behaves, and could therefore revolutionise our understanding of physics interaction at the smallest distances.
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