Report
Teaser, summary, work performed and final results
Periodic Reporting for period 2 - PRECISION (Precision measurements to discover new scalar and vector particles)
Teaser
The Standard Model of particle physics successfully describes all known particles and their interactions. However,questions like the nature of dark matter or the hierarchy of masses and couplings of quarks and leptons remain to beunderstood. Hence, one searches for new...
Summary
The Standard Model of particle physics successfully describes all known particles and their interactions. However,
questions like the nature of dark matter or the hierarchy of masses and couplings of quarks and leptons remain to be
understood. Hence, one searches for new phenomena that will lead to a superior theory that can explain these questions.
All such theories introduce additional quantum corrections. Decay rates of processes which are strongly suppressed in the
Standard Model are highly sensitive to these corrections.
The ERC project PRECISION aims to discover new scalar or vector particles in precision measurements of leptonic and semi-leptonic
beauty decays. These new particles are not predicted by the Standard Model of particle physics, a potential discovery
would mark the most important finding in High Energy Physics of the last decades. Some existing anomalies in flavour data
can be interpreted as hints for the particles searched for in this proposal. Two classes of measurements are planned within
this project: a scan of purely leptonic beauty decays which include flavour changing neutral current as well as
lepton flavour violating modes. Lepton flavour universality is tested in loop decays through a novel inclusive strategy. All
proposed measurements will advance the world’s knowledge significantly and have a large discovery potential.
Work performed
The project PRECISION has two main work areas: the scan of purely leptonic beauty decays including the search for lepton flavour violation and the test of lepton flavour universality. The team members of the ERC grant PRECISION have made significant contributions to the publicaiotn of beauty decays to two muons [Phys. Rev. Lett. 118 (2017) 191801] and have guided LHCb\'s researchers for a search for B -> e mu [JHEP 03 (2018) 078]. The not so sensitive decays to tau leptons have been published by the LHCb collaboration independently of PRECISION [Phys. Rev. Lett. 118 (2017) 251802]. The researchers of PRECISION have then focussed on a search for Lepton Flavour Violation in B-> Kemu decays, one of the most interesting modes of this kind. The analysis is finished and has been presented by the PRECISION researcher Titus Mombächer on the MIAPP workshop in May 2018. Submission to the journal and preprint server has happened recently, the paper is available on the preprin server [arXiv:1909.01010]. The secon focus in this area is the search for purely electronic B decays, the search for B and Bs -> e+e-. This search is at a very advanced state, it has recently entered collaboration wide review.
The work area of PRECISION is the test of Lepton Flavour Universality. Here, the combined test of Lepton Flavour Universality in decays of Bu->Kmumu / Bu->Kee and Bd->K*mumu / Bd->K*ee is ongoing and progressing well. The analysis is performed in a large research team (members include the groups of Dr. Gligorov (Paris), Dr. Schune (Orsay) and Dr. Bifani (Birmingham). An extensive code-base has been developed and the analysis of the data is progressing very well. After publication of this analysis, the code base and analysis framework will be extended to the fully inclusive analysis that includes the sum of all sensitive exclusive modes.
Final results
The project PRECISION has already produced several world leading results, see above. Expected results until the end of the project include:
- the full analysis of LHCb\'s Run 1 and Run 2 dataset for Bs->mumu, giving the most stringent limits on new scalar interactions.
- publication of B->ee, giving the most stringent bounds on new scalars coupling to electrons by more than an order of magnitude
- publicaiton of an inclusive test of Lepton Flavour Universality, that is likely to clear the view on the current anomalies
Additionally to the analyses published, the code-base developed for the LFU analysis sets a new scale for state-of-the-art analysis
code in LHCb and is already been used by several following analyses.
Website & more info
More info: https://www.e5.physik.tu-dortmund.de/albrecht.