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Register a new userConstraints of unparticle physics parameters from $K^0-bar K^0$ mixing
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The neutral kaon meson mixing plays an important role in test of the Standard Model (SM) and new physics beyond it. Scale invariant unparticle physics induces a flavor changing neutral current (FCNC) transition of $K^0-bar K^0$ oscillation at the tree level. In this study, we investigate the scale invariant unparticle physics effects on the $K^0-bar K^0$ mixing. Based on the current experimental data, we give constraints of $K^0-bar K^0$ mixing on the unparticle parameters.
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We present results for Delta I=3/2 and Delta S=2 matrix elements relevant for CP violation in K->Pi Pi decays and for the K_S-K_L mass difference in the standard model and beyond. They were obtained with Neuberger fermions on quenched gauge configurations generated with the Wilson plaquette action at beta=6.0 on an 18^3x64 lattice.
We calculate BSM hadronic matrix elements for $K^0-bar K^0$ mixing in the Dual QCD approach (DQCD). The ETM, SWME and RBC-UKQCD lattice collaborations find the matrix elements of the BSM density-density operators $mathcal{O}_i$ with $i=2-5$ to be rather different from their vacuum insertion values (VIA) with $B_2approx 0.5$, $B_3approx B_5approx 0.7$ and $B_4approx 0.9$ at $mu=3~GeV$ to be compared with $B_i=1$ in the VIA. We demonstrate that this pattern can be reconstructed within the DQCD through the non-perturbative meson evolution from very low scales, where factorization of matrix elements is valid, to scales of order $(1~GeV)$ with subsequent perturbative quark-gluon evolution to $mu=3~GeV$. This turns out to be possible in spite of a very different pattern displayed at low scales with $B_2=1.2$, $B_3=3.0$, $B_4=1.0$ and $B_5approx 0.2$ in the large $N$ limit, $N$ being the number of colours. Our results imply that the inclusion of meson evolution in the phenomenology of any non-leptonic transition like $K^0-bar K^0$ mixing and $Ktopipi$ decays is mandatory. While meson evolution, as demonstrated in our paper, is hidden in LQCD results, to our knowledge DQCD is the only analytic approach for non-leptonic transitions and decays which takes this important QCD dynamics into account.
Recently the branching ratios for $B^+to K^+bar K^0$ and $B^0 to K^0 bar K^0$ have been measured. Data indicate that the annihilation amplitudes in these decays are not zero. A non-zero annihilation amplitude plays an important role in CP violation for $B^+to pi^+ K^0, K^+ bar K^0$. Using the measured branching ratios for these decays, we show that there is an absolute bound of 5% for the size of CP asymmetry in $B^+to pi^+ K^0$ from a relation between the amplitudes of these decays. The size of CP asymmetry in $B^+ to K^+bar K^0$ can, however, be as large as 90%. Future experimental data will test these predictions.
We consider the K^0 - bar K^0 and B^0 - bar B^0 mixings in the MSSM with the two-Higgs-doublet scalar sector featuring explicit CP violation, and the Yukawa sector of type II. In the case of strong mixing between CP-odd and CP-even states the existence of light charged Higgs is allowed in the model. The mass splitting Delta m_{LS} and the amount of indirect CP violation epsilon are calculated. In the limit of effective low-energy approximation the nonstandard effects are shown to be negligibly small in Delta m_{LS} and epsilon for the K^0-mesons, being almost independent on the charged Higgs boson mass. However, for the B_d^0 - bar B_d^0 and B_s^0 - bar B_s^0 systems the effects of nonstandard physics are shown to be larger, limiting the MSSM parameter space.
We provide a comprehensive, up-to-date analysis of possible New Physics contributions to the mass difference $Delta M_D$ in $D^0$-${bar D}^0$ mixing. We consider the most general low energy effective Hamiltonian and include leading order QCD running of effective operators. We then explore an extensive list of possible New Physics models that can generate these operators, which we organize as including Extra Fermions, Extra Gauge Bosons, Extra Scalars, Extra Space Dimensions and Extra Symmetries. For each model we place restrictions on the allowed parameter space using the recent evidence for observation of $D$ meson mixing. In many scenarios, we find strong constraints that surpass those from other search techniques and provide an important test of flavor changing neutral currents in the up-quark sector. We also review the recent BaBar and Belle findings, and describe the current status of the Standard Model predictions of $D^0$-${bar D}^0$ mixing.
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