Simultaneous determination of CKM angle γ and charm mixing parameters

A combination of measurements sensitive to the CP violation angle γ of the Cabibbo-Kobayashi-Maskawa unitarity triangle and to the charm mixing parameters that describe oscillations between D0 and $$ \overline{D} $$ D ¯ 0 mesons is performed. Results from the charm and beauty sectors, based on data collected with the LHCb detector at CERN’s Large Hadron Collider, are combined for the first time. This method provides an improvement on the precision of the charm mixing parameter y by a factor of two with respect to the current world average. The charm mixing parameters are determined to be $$ x=\left({0.400}_{-0.053}^{+0.052}\right)\% $$ x = 0.400 − 0.053 + 0.052 % and y = $$ \left({0.630}_{-0.030}^{+0.033}\right)\% $$ 0.630 − 0.030 + 0.033 % . The angle γ is found to be γ = $$ \left({65.4}_{-4.2}^{+3.8}\right){}^{\circ} $$ 65.4 − 4.2 + 3.8 ° and is the most precise determination from a single experiment.

Implications of precision measurements and unitarity on CKM paradigm

In the context of precise measurements in some of the CKM elements and angles of the unitarity triangle coupled with latest theoretical improvements of lattice QCD calculations of “hadronic factors,” we have explored the implication of these and unitarity on some of the CKM parameters which are ridden with ambiguities. In particular, we have undertaken a thorough scrutiny of the implications of the precise measurements of the angles of the unitarity triangle along with the element [Formula: see text], on the [Formula: see text], [Formula: see text], [Formula: see text], as well as the CP violating parameter [Formula: see text]. Interestingly, we find a unitarity-based analysis while unambiguously favoring [Formula: see text] exclusive-over-inclusive value which is also in agreement with the present data pertaining to [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], etc. The present analysis also shows that the presence of NP in [Formula: see text] and [Formula: see text] systems, if any, would be less than a few percent only.

Test of the fourth quark generation from the Cabibbo–Kobayashi–Maskawa matrix

The structure of the mixing matrix in the electroweak quark sector with four generations of quarks is investigated. We conclude that the area of the unitarity quadrangle is not a good choice as a possible measure of the CP violation. In search of new physics, we analyze how the existence of the fourth quark family may influence on the values of the Cabibbo–Kobayashi–Maskawa matrix and we show that one can test for the existence of the fourth generation using the Jarlskog invariants of the known quarks only. The analysis based on the measured unitary triangle exhibits some tension with the assumption of three quark generations. The measurement of the unitarity triangle obtained from the scalar product of the second row/column of the CKM matrix by the complex conjugate of third row/column can provide information about the existence of the fourth generation of quarks.

Measurement of the D → K−π+π+π− and D → K−π+π0 coherence factors and average strong-phase differences in quantum-correlated $$ D\overline{D} $$ decays

The decays D → K−π+π+π− and D → K−π+π0 are studied in a sample of quantum-correlated $$ D\overline{D} $$ D D ¯ pairs produced through the process e+e− → ψ(3770) → $$ D\overline{D} $$ D D ¯ , exploiting a data set collected by the BESIII experiment that corresponds to an integrated luminosity of 2.93 fb−1. Here D indicates a quantum superposition of a D0 and a $$ {\overline{D}}^0 $$ D ¯ 0 meson. By reconstructing one neutral charm meson in a signal decay, and the other in the same or a different final state, observables are measured that contain information on the coherence factors and average strong-phase differences of each of the signal modes. These parameters are critical inputs in the measurement of the angle γ of the Unitarity Triangle in B− → DK− decays at the LHCb and Belle II experiments. The coherence factors are determined to be RK3π = $$ {0.52}_{-0.10}^{+0.12} $$ 0.52 − 0.10 + 0.12 and $$ {R}_{K{\pi \pi}^0} $$ R K ππ 0 = 0.78 ± 0.04, with values for the average strong-phase differences that are $$ {\delta}_D^{K3\pi }=\left({167}_{-19}^{+31}\right){}^{\circ} $$ δ D K 3 π = 167 − 19 + 31 ° and $$ {\delta}_D^{K{\pi \pi}^0}=\left({196}_{-15}^{+14}\right){}^{\circ} $$ δ D K ππ 0 = 196 − 15 + 14 ° , where the uncertainties include both statistical and systematic contributions. The analysis is re-performed in four bins of the phase-space of the D → K−π+π+π− to yield results that will allow for a more sensitive measurement of γ with this mode, to which the BESIII inputs will contribute an uncertainty of around 6°.

The impact of nonminimal universal extra dimensional model on $$\Delta B=2$$ transitions

We measure the impact of nonvanishing boundary localised terms on $$\Delta B=2$$ Δ B = 2 transitions in five-dimensional Universal Extra Dimensional scenario where masses and coupling strengths of several interactions of Kaluza–Klein modes are significantly modified with respect to the minimal counterpart. In such scenario we estimate the Kaluza–Klein contributions of quarks, gauge bosons and charged Higgs by evaluating the one-loop box diagrams that are responsible for the $$\Delta B=2$$ Δ B = 2 transitions. Using the loop function (obtained from one-loop box diagrams) we determine several important elements that are involved in Wolfenstein parametrisation. Moreover, with these elements we also study the geometrical shape of unitarity triangle. Besides, we compute the quantity $$\Delta M_s$$ Δ M s scaled by the corresponding Standard Model value. Outcomes of our theoretical predictions have been compared to the allowed ranges of the corresponding observables simultaneously. Our current analysis shows that, depending on the parameters in this scenario the lower limit on the inverse of the radius of compactification can reach to an appreciable large value ($$\approx 1.48$$ ≈ 1.48 TeV or even higher).

Global oscillation data analysis on the 3ν mixing without unitarity

We present results of a combined analysis in neutrino oscillations without unitarity assumption in the 3ν mixing picture. Constraints on neutrino mixing matrix elements are based on recent data from the reactor, solar and long-baseline accelerator neutrino oscillation experiments. The current data are consistent with the standard 3ν scheme. The precision on different matrix elements can be as good as a few percent at 3σ CL, and is mainly limited by the experimental statistical uncertainty. The νe related elements are the most precisely measured among all sectors with the uncertainties < 20%. The measured leptonic CP violation is very close to the one assuming the standard 3ν mixing. The deviations on normalization and the unitarity triangle closure are confined within $$ \mathcal{O} $$ O (10−3), $$ \mathcal{O} $$ O (10−2) and $$ \mathcal{O} $$ O (10−1), for νe, νμ and ντ sectors, respectively. We look forward to the next-generation neutrino oscillation experiments such as DUNE, T2HK, and JUNO, especially the precision measurements on ντ oscillations, to significantly improve the precision of unitarity test on the 3ν mixing matrix.