Periodic Reporting for period 1 - charming-DecaDe (A charming decade: using colliders to probe the charm sector of the Standard Model and Beyond)
Período documentado: 2021-11-01 hasta 2023-10-31
The large asymmetry between matter and anti-matter in the visible universe is one of the most intriguing open questions, hinting at new sources of Charge-Parity Violation (CPV). In the context of charm-meson decays, CPV was discovered very recently, by LHCb in 2019, establishing CPV in a new sector after decades of experimental efforts. It is yet unknown whether the Standard Model (SM) of particle physics can explain such a measurement, or whether it signals the emergence of Beyond the SM (BSM) sources of CPV: this difficulty is due to the presence of non-perturbative QCD effects that are extremely challenging to describe, precluding more in depth studies of electroweak dynamics.
Another puzzling phenomenon is the structure of flavor, namely, the spectrum of fermion masses and the hierarchy of charged-current couplings in the quark sector. Together with the gauge structure of the SM, these features are intimately connected to the properties of flavor changing neutral-currents. For their study, one must face again non-perturbative QCD effects, which are ubiquitous when dealing with quarks, such as in charm physics. Like in the case of CPV, in order to improve our knowledge about electroweak interactions it is necessary to better understand the underlying strong dynamics.
I stress that achieving an accurate description of the SM dynamics at play in charm physics naturally leads to an enhanced sensitivity to BSM physics. The analysis of future data may lead to the indirect observation of BSM, which would certainly be a major breakthrough in particle physics. Moreover, being able to clearly identify hints of BSM via the usage of flavor observables is sought after, since it would help in producing BSM particles directly. The ongoing experiments LHCb and Belle II, and the proposal for extending BESIII, whose total luminosities will be highly increased in the years to come, have a comprehensive experimental program on charm physics. It is thus necessary to dedicate equivalent efforts from the theoretical side to fully exploit foreseen experimental achievements.
Furthermore, the quest for precision in particle physics can benefit from new, developing technologies. Indeed, quantum devices will change the way we do research, and unlocking the potential of quantum computers to perform higher order perturbative calculations and beyond is an exciting endeavor.
Another puzzling phenomenon is the structure of flavor, namely, the spectrum of fermion masses and the hierarchy of charged-current couplings in the quark sector. Together with the gauge structure of the SM, these features are intimately connected to the properties of flavor changing neutral-currents. For their study, one must face again non-perturbative QCD effects, which are ubiquitous when dealing with quarks, such as in charm physics. Like in the case of CPV, in order to improve our knowledge about electroweak interactions it is necessary to better understand the underlying strong dynamics.
I stress that achieving an accurate description of the SM dynamics at play in charm physics naturally leads to an enhanced sensitivity to BSM physics. The analysis of future data may lead to the indirect observation of BSM, which would certainly be a major breakthrough in particle physics. Moreover, being able to clearly identify hints of BSM via the usage of flavor observables is sought after, since it would help in producing BSM particles directly. The ongoing experiments LHCb and Belle II, and the proposal for extending BESIII, whose total luminosities will be highly increased in the years to come, have a comprehensive experimental program on charm physics. It is thus necessary to dedicate equivalent efforts from the theoretical side to fully exploit foreseen experimental achievements.
Furthermore, the quest for precision in particle physics can benefit from new, developing technologies. Indeed, quantum devices will change the way we do research, and unlocking the potential of quantum computers to perform higher order perturbative calculations and beyond is an exciting endeavor.
The main achievement during the period covered by the action was the theoretical prediction of observables that measure CPV in hadronic two-body charm-meson decays. For this sake, I considered a data-driven approach based on light meson rescattering information, and the experimental values of the branching ratios of the relevant charm-meson decays. I obtained that the current prediction cannot reproduce the experimental measurement, claiming for more dedicated studies in order to achieve its full interpretation.
To give continuity to this research in a different front, I started investigating CPV in distinct categories of hadronic two-body charm-meson decays. A novel feature is the possibility of having qualitatively different contributions to CP asymmetries due to the presence of CPV in the mixing of kaons.
As part of my investigation in CPV, I performed an update of the extraction of, in particular, the level of CPV in the SM needed to describe the measurements of CPV across distinct quark flavor sectors. The SM is able to provide a consistent overall picture of precision quark flavor observables, which will be challenged to unprecedented levels by data that is being accumulated by ongoing experiments.
Regarding rare charm-meson transitions, I exploited the recent LHCb dataset in order to draw a more systematic and accurate description of the non-perturbative dynamics at play; I also defined new observables that will help achieving an even better understanding of this process. Based on a model consisting of the possible intermediate resonant contributions, I was able to describe all the main features of the differential branching ratios, and most angular observables measured by LHCb.
Shifting to New Physics, the calculation of new radiative effects helps in setting bounds on their contributions to meson mixing observables. The calculation I performed consisted in analyzing double-insertions of operators of dimension-six; due to both the high precision of SM predictions and experimental measurements, impressive bounds on the New Physics energy scale were set.
I also investigated bounds on New Physics contributions based on the direct search of new force-mediators at the LHC collider. I discussed how the full set of parameters of the model under analysis (namely, Left-Right Models) impacts the simplistic bounds that are sometimes quoted. I then set more robust lower limits on the masses of new charged and neutral gauge bosons.
In parallel, I started investigating applications of quantum computers. This technology has the potential to speed up computational tasks that are hard for classical computers. I investigated the usage of graphs in representing problems of particle physics. The full perturbative calculation of Feynman diagrams to high orders represents an outstandingly difficult problem, and I showed how this task can be facilitated in the landscape of near-feature quantum devices.
These results are available through open-access articles, and have been advertised in multiple occasions (notably, CKM2023, EPS-HEP2023, ICHEP2022).
To give continuity to this research in a different front, I started investigating CPV in distinct categories of hadronic two-body charm-meson decays. A novel feature is the possibility of having qualitatively different contributions to CP asymmetries due to the presence of CPV in the mixing of kaons.
As part of my investigation in CPV, I performed an update of the extraction of, in particular, the level of CPV in the SM needed to describe the measurements of CPV across distinct quark flavor sectors. The SM is able to provide a consistent overall picture of precision quark flavor observables, which will be challenged to unprecedented levels by data that is being accumulated by ongoing experiments.
Regarding rare charm-meson transitions, I exploited the recent LHCb dataset in order to draw a more systematic and accurate description of the non-perturbative dynamics at play; I also defined new observables that will help achieving an even better understanding of this process. Based on a model consisting of the possible intermediate resonant contributions, I was able to describe all the main features of the differential branching ratios, and most angular observables measured by LHCb.
Shifting to New Physics, the calculation of new radiative effects helps in setting bounds on their contributions to meson mixing observables. The calculation I performed consisted in analyzing double-insertions of operators of dimension-six; due to both the high precision of SM predictions and experimental measurements, impressive bounds on the New Physics energy scale were set.
I also investigated bounds on New Physics contributions based on the direct search of new force-mediators at the LHC collider. I discussed how the full set of parameters of the model under analysis (namely, Left-Right Models) impacts the simplistic bounds that are sometimes quoted. I then set more robust lower limits on the masses of new charged and neutral gauge bosons.
In parallel, I started investigating applications of quantum computers. This technology has the potential to speed up computational tasks that are hard for classical computers. I investigated the usage of graphs in representing problems of particle physics. The full perturbative calculation of Feynman diagrams to high orders represents an outstandingly difficult problem, and I showed how this task can be facilitated in the landscape of near-feature quantum devices.
These results are available through open-access articles, and have been advertised in multiple occasions (notably, CKM2023, EPS-HEP2023, ICHEP2022).
Let me first highlight that PRD 108 (2023) 3, 036026 (arXiv:2305.11951 [hep-ph]) constitutes the first time a full dispersive analysis has been employed and confronted with CP asymmetries. This work provides a model-independent data-driven description of rescattering effects, assuming the main contributions can be estimated via a two-channel coupled description.
The study of arXiv:2312.07501 [hep-ph] to be published in PRD provides the first quantitative analysis of an S-wave contribution in rare charm-meson decays, thus improving the SM description. Furthermore, this work provides the first quantitative description of LHCb binned data, out of which we identified the main ingredients necessary for a successful description of such data. Finally, it provides new observables testing the SM, which are straightforward to be measured by LHCb in the future.
The leading-order calculation of arXiv:2201.03038 [hep-ph] gives the first quantitative assessment of the size of contributions to meson mixing of double-insertions of dimension-6 SMEFT operators, thus setting novel bounds on their Wilson coefficients.
The article JHEP02(2024)027 (arXiv:2309.06094 [hep-ph]) reviews for the first time the full set of parameters affecting collider bounds on Left-Right Model (LRM) heavy gauge bosons. This work has a clear impact on the phenomenology of these models, since it alleviates previous limits, bringing LRM effects in flavor observables closer to observable levels.
In PRD 108 (2023) 9, 096035 (arXiv:2210.13240 [hep-ph]) we successfully tested, for the first time, a VQE-based strategy to solve a problem with highly-degenerated ground-states, which constitutes a hard stress-test for this kind of minimization algorithms. The work I have developed about directed acyclic graphs (in particular the recognition of the importance of their spectral properties) could have a sizable impact in society, as many problems (e.g. internet networks) are modeled by graphs.
The study of arXiv:2312.07501 [hep-ph] to be published in PRD provides the first quantitative analysis of an S-wave contribution in rare charm-meson decays, thus improving the SM description. Furthermore, this work provides the first quantitative description of LHCb binned data, out of which we identified the main ingredients necessary for a successful description of such data. Finally, it provides new observables testing the SM, which are straightforward to be measured by LHCb in the future.
The leading-order calculation of arXiv:2201.03038 [hep-ph] gives the first quantitative assessment of the size of contributions to meson mixing of double-insertions of dimension-6 SMEFT operators, thus setting novel bounds on their Wilson coefficients.
The article JHEP02(2024)027 (arXiv:2309.06094 [hep-ph]) reviews for the first time the full set of parameters affecting collider bounds on Left-Right Model (LRM) heavy gauge bosons. This work has a clear impact on the phenomenology of these models, since it alleviates previous limits, bringing LRM effects in flavor observables closer to observable levels.
In PRD 108 (2023) 9, 096035 (arXiv:2210.13240 [hep-ph]) we successfully tested, for the first time, a VQE-based strategy to solve a problem with highly-degenerated ground-states, which constitutes a hard stress-test for this kind of minimization algorithms. The work I have developed about directed acyclic graphs (in particular the recognition of the importance of their spectral properties) could have a sizable impact in society, as many problems (e.g. internet networks) are modeled by graphs.