Periodic Reporting for period 1 - CharmAsymmetries (The charm of asymmetries or the asymmetries in charm (entangled edition))
Período documentado: 2019-09-23 hasta 2021-09-22
There is an apparent excess of matter over antimatter in the Universe. To generate this imbalance, Sakharov postulated three conditions one of which is a violation of the charge-parity (CP) symmetry. The charge-parity CP operator transforms a particle into its antiparticle and reverses the spatial coordinates of the physical system: properties such as the momentum, the helicity, and the electrical charge, are mirrored under this transformation. The principle of CP symmetry states that all processes must remain unchanged under a CP operation. The violation of this symmetry (CPV) is one of the conditions required to create the observed asymmetry between matter and antimatter in our universe. Within the SM all CPV in the quark sector is encoded in a single phase in the Cabibbo-Kobayashi-Maskawa (CKM) 3, 4 quark mixing matrix. However, The SM cannot explain the scale of the observed excess of cosmic matter over antimatter in our Universe, giving a prediction too small by several orders of magnitude. This is one of the most important fundamental puzzles, closely connected to our very existence. Therefore, it is of utmost importance to look for new sources of CP asymmetry. Finding and studying new sources of matter antimatter asymmetry in particles containing charm quarks is the holy grail of this field of research and is the focus of this proposal.
This proposal consists of the following objectives, of equal importance:
1. To develop a model-independent unbinned method to extract the information of the strong phase variation in every point of phase space of the D0->KSπ+π- decays using QE charm meson pair data collected by the BESIII experiment, and to apply this information to measurements of the charm mixing and CP violation at the LHCb experiment.
2. To search for direct CP violation of charm two-body decays D0 -> K*0KS and D0 -> anti-K*0KS at the LHCb experiment using the full available data sample collected during LHC Run 1 and Run 2 exploiting two different techniques.
This proposal consists of the following objectives, of equal importance:
1. To develop a model-independent unbinned method to extract the information of the strong phase variation in every point of phase space of the D0->KSπ+π- decays using QE charm meson pair data collected by the BESIII experiment, and to apply this information to measurements of the charm mixing and CP violation at the LHCb experiment.
2. To search for direct CP violation of charm two-body decays D0 -> K*0KS and D0 -> anti-K*0KS at the LHCb experiment using the full available data sample collected during LHC Run 1 and Run 2 exploiting two different techniques.
1. Charm strong phases and mixing and CPV parameters with D0->KSπ+π- decays: A model-dependent unbinned method for the measurement of the strong phase variation in every point of phase space of D0->KSπ+π- decay using Quantum Entangled charm meson pair data of BESIII experiment is still under development. The method paper is being drafted, and we are in the final steps of comparing the new method sensitivity to other traditionally used methods. This is now lead by a PhD student, and we aim to submit a publication before the end of the year.
The method will be tested on data from the BESIII experiment. The aim is to measure/ model the strong phases behaviour in every point of the Dalitz plot (the phase space). The selection of the quantum entangled charm meson pairs has been finalised by the fellow, the signal yields and efficiencies of the tag modes and the signal mode have been measured via a fit, and the data samples are ready for analysis with the new method. This should be finalised in the coming months.
The fellow provided a useful input for the study of the intermediate resonances contributing to the D0->KSπ+π- decay with data from the LHCb experiment; this study will result in the charm mixing parameters measurement. The paper draft is in internal review by the LHCb collaboration.
The fellow went twice to Beijing for data taking shifts at the BESIII experiment.
2. Direct CPV in charm: Search for direct CP violation in the D0->(anti-)K*0KS decays. The analysis will use the three body final states D0->KSK-pi+ and D0->KSK+pi-: The data selection was finalised (one of the final states was selected by the fellow, and the other one by a PhD student), and planned training a multivariate classifier but it was deemed unnecessary. The fellow studied the efficiencies with simulation, and implemented them in a sensitivity study for which the GOOFIT package. The sensitivity study informed the choice of a tunable parameter used in the model-independent technique called The Energy test. A couple of talks were given within the LHCb collaboration internal working group meetings. The analysis is now lead by a PhD student, an internal note is prepared for internal review and will form the base of a publication which will be released after an approval by the collaboration. The results will remain blind until then.
3.The fellow has been trained how to perform an offline analysis at the LHCb experiment and use specific software for the experiment. The fellow has followed a training on programming on GPUs.
The method will be tested on data from the BESIII experiment. The aim is to measure/ model the strong phases behaviour in every point of the Dalitz plot (the phase space). The selection of the quantum entangled charm meson pairs has been finalised by the fellow, the signal yields and efficiencies of the tag modes and the signal mode have been measured via a fit, and the data samples are ready for analysis with the new method. This should be finalised in the coming months.
The fellow provided a useful input for the study of the intermediate resonances contributing to the D0->KSπ+π- decay with data from the LHCb experiment; this study will result in the charm mixing parameters measurement. The paper draft is in internal review by the LHCb collaboration.
The fellow went twice to Beijing for data taking shifts at the BESIII experiment.
2. Direct CPV in charm: Search for direct CP violation in the D0->(anti-)K*0KS decays. The analysis will use the three body final states D0->KSK-pi+ and D0->KSK+pi-: The data selection was finalised (one of the final states was selected by the fellow, and the other one by a PhD student), and planned training a multivariate classifier but it was deemed unnecessary. The fellow studied the efficiencies with simulation, and implemented them in a sensitivity study for which the GOOFIT package. The sensitivity study informed the choice of a tunable parameter used in the model-independent technique called The Energy test. A couple of talks were given within the LHCb collaboration internal working group meetings. The analysis is now lead by a PhD student, an internal note is prepared for internal review and will form the base of a publication which will be released after an approval by the collaboration. The results will remain blind until then.
3.The fellow has been trained how to perform an offline analysis at the LHCb experiment and use specific software for the experiment. The fellow has followed a training on programming on GPUs.
See the point above for a summary of the work completed, and expected results (several of which are delayed but worked on my the team). All resulting publications will be open access as a standard in experimental particle physics. No website has been developed for the project.