Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userDual QCD Insight into BSM Hadronic Matrix Elements for $K^0-bar K^0$ Mixing from Lattice QCD
73
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
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.
rate research
Read More
We perform for the first time a direct calculation of on-shell $Ktopipi$ hadronic matrix elements of chromomagnetic operators (CMO) in the Standard Model and beyond. To his end, we use the successful Dual QCD (DQCD) approach in which we also consider off-shell $K-pi$ matrix elements that allows the comparison with lattice QCD calculations of these matrix elements presented recently by the ETM collaboration. Working in the SU(3) chiral limit, we find for the single $B$ parameter $B_{rm CMO}=0.33$. Using the numerical results provided by the ETM collaboration we argue that only small corrections beyond that limit are to be expected. Our results are relevant for new physics scenarios in the context of the emerging $epsilon^prime/epsilon$ anomaly strongly indicated within DQCD and supported by RBC-UKQCD lattice collaboration.
We calculate in three-flavor lattice QCD the short-distance hadronic matrix elements of all five $Delta C=2$ four-fermion operators that contribute to neutral $D$-meson mixing both in and beyond the Standard Model. We use the MILC Collaborations $N_f = 2+1$ lattice gauge-field configurations generated with asqtad-improved staggered sea quarks. We also employ the asqtad action for the valence light quarks and use the clover action with the Fermilab interpretation for the charm quark. We analyze a large set of ensembles with pions as light as $M_pi approx 180$ MeV and lattice spacings as fine as $aapprox 0.045$ fm, thereby enabling good control over the extrapolation to the physical pion mass and continuum limit. We obtain for the matrix elements in the $overline{text{MS}}$-NDR scheme using the choice of evanescent operators proposed by Beneke emph{et al.}, evaluated at 3 GeV, $langle D^0|mathcal{O}_i|bar{D}^0 rangle = {0.0805(55)(16), -0.1561(70)(31), 0.0464(31)(9), 0.2747(129)(55), 0.1035(71)(21)}~text{GeV}^4$ ($i=1$--5). The errors shown are from statistics and lattice systematics, and the omission of charmed sea quarks, respectively. To illustrate the utility of our matrix-element results, we place bounds on the scale of CP-violating new physics in $D^0$~mixing, finding lower limits of about 10--50$times 10^3$ TeV for couplings of $mathrm{O}(1)$. To enable our results to be employed in more sophisticated or model-specific phenomenological studies, we provide the correlations among our matrix-element results. For convenience, we also present numerical results in the other commonly-used scheme of Buras, Misiak, and Urban.
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.
Predicting the $B_s^0-bar{B}_s^0$ width difference $DeltaGamma_s$ relies on the heavy quark expansion and on hadronic matrix elements of $Delta B=2$ operators. We present the first lattice QCD results for matrix elements of the dimension-7 operators $R_{2,3}$ and linear combinations $tilde{R}_{2,3}$ using nonrelativistic QCD for the bottom quark and a highly improved staggered quark (HISQ) action for the strange quark. Computations use MILC ensembles of gauge field configuations with $2+1+1$ flavors of sea quarks with the HISQ discretization, including lattices with physically light up/down quark masses. We discuss features unique to calculating matrix elements of these operators and analyze uncertainties from series truncation, discretization, and quark mass dependence. Finally we report the first Standard Model determination of $DeltaGamma_s$ using lattice QCD results for all hadronic matrix elements through $mathcal{O}(1/m_b)$. The main result of our calculations yields the $1/m_b$ contribution $Delta Gamma_{1/m_b} = -0.022(10)~mathrm{ps}^{-1}$. Adding this to the leading order contribution, the Standard Model prediction is $Delta Gamma_s = 0.092(14)~mathrm{ps}^{-1}$.
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.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
