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The rare kaon decays $K\to\pi\nu\bar{\nu}$ are strongly suppressed in the standard model and widely regarded as processes in which new phenomena, not predicted by the standard model, may be observed. Recognizing such new phenomena requires…

High Energy Physics - Lattice · Physics 2016-07-06 Norman H. Christ , Xu Feng , Antonin Portelli , Christopher T. Sachrajda

The rare kaon decays $K\to\pi\ell^+\ell^-$ and $K\to\pi\nu\bar{\nu}$ are flavor changing neutral current (FCNC) processes and hence promising channels with which to probe the limits of the standard model and to look for signs of new…

High Energy Physics - Lattice · Physics 2016-01-29 N. H. Christ , X. Feng , A. Portelli , C. T. Sachrajda

The calculation of the long-distance contribution to the $K^0-\bar{K}^0$ mass matrix is divided into three parts: First, the calculation of the matrix element between kaon states of the product of two space-time integrated, $\Delta S=1$,…

High Energy Physics - Lattice · Physics 2010-12-30 Norman H. Christ

A lattice QCD approach to the calculation of the long-distance contributions to $\epsilon_K$ is presented. This parameter describes indirect CP violation in $K\to\pi\pi$ decay. While the short-distance contribution to $\epsilon_K$ can be…

High Energy Physics - Lattice · Physics 2023-09-06 Ziyuan Bai , Norman H. Christ , Joseph M. Karpie , Christopher T. Sachrajda , Amarjit Soni , Bigeng Wang

We show that long distance contributions to the rare decays K -> pi nu nu-bar and K -> pi l+ l- can be computed using lattice QCD. The proposed approach requires well established methods, successfully applied in the calculations of…

High Energy Physics - Lattice · Physics 2009-11-11 Gino Isidori , Guido Martinelli , Paolo Turchetti

The rare decays of a kaon into a pion and a charged lepton/antilepton pair proceed via a flavour changing neutral current and therefore may only be induced beyond tree level in the Standard Model. This natural suppression makes these decays…

High Energy Physics - Lattice · Physics 2016-02-04 Norman Christ , Xu Feng , Andreas Juttner , Andrew Lawson , Antonin Portelli , Christopher Sachrajda

We report a first, complete lattice QCD calculation of the long-distance contribution to the $K^+\to\pi^+\nu\bar{\nu}$ decay within the standard model. This is a second-order weak process involving two four-Fermi operators that is highly…

High Energy Physics - Lattice · Physics 2017-06-28 Ziyuan Bai , Norman H. Christ , Xu Feng , Andrew Lawson , Antonin Portelli , Christopher T. Sachrajda

The largest contribution to the CP violating K_L-K_S mixing parameter \epsilon_K comes from second order weak interactions at short distances and can be accurately determined by a combination of electroweak perturbation theory and the…

High Energy Physics - Lattice · Physics 2012-01-11 Norman H. Christ

In Ref [1] we have presented the results of an exploratory lattice QCD computation of the long-distance contribution to the $K^+\to\pi^+\nu\bar{\nu}$ decay amplitude. In the present paper we describe the details of this calculation, which…

High Energy Physics - Lattice · Physics 2018-10-24 Ziyuan Bai , Norman H. Christ , Xu Feng , Andrew Lawson , Antonin Portelli , Christopher T. Sachrajda

We develop and demonstrate techniques needed to compute the long distance contribution to the $K_{L}$-$K_{S}$ mass difference, $\Delta M_K$, in lattice QCD and carry out a first, exploratory calculation of this fundamental quantity. The…

High Energy Physics - Lattice · Physics 2013-12-24 N. H. Christ , T. Izubuchi , C. T. Sachrajda , A. Soni , J. Yu

Standard lattice calculations in kaon physics are based on the evaluation of matrix elements of local operators between two single-hadron states or a single-hadron state and the vacuum. Recent progress in lattice QCD has gone beyond these…

High Energy Physics - Lattice · Physics 2018-04-18 Xu Feng

We present a method to non-perturbatively determine the long-distance contribution to the $K_{L}$-$K_{S}$ mass difference. The calculation is performed on 2+1 flavor, domain wall fermion, $16^3\times32$ configurations with a 421 MeV pion…

High Energy Physics - Lattice · Physics 2012-12-04 Jianglei Yu

The rare decays of a kaon into a pion and a charged lepton/antilepton pair proceed via a flavour changing neutral current and therefore may only be induced beyond tree level in the Standard Model. This natural suppression makes these decays…

High Energy Physics - Lattice · Physics 2017-04-04 Norman H. Christ , Xu Feng , Andreas Juttner , Andrew Lawson , Antonin Portelli , Christopher T. Sachrajda

A method for analysing the hadronic resonance contributions in $\bar{B}^{0} \rightarrow \bar{K}^{*0}\mu^{+}\mu^{-}$ decays is presented. This method uses an empirical model that relies on measurements of the branching fractions and…

High Energy Physics - Phenomenology · Physics 2018-06-08 Thomas Blake , Ulrik Egede , Patrick Owen , Gabriela Pomery , Konstantinos Alexandros Petridis

We compute the complex, long-distance two-photon-exchange amplitude which contributes to the rare $K_{\rm L}\rightarrow\mu^+\mu^-$ decay from lattice QCD. We use a $24^3\times 64$ physical-pion-mass gauge field ensemble at an inverse…

High Energy Physics - Lattice · Physics 2025-11-06 Peter Boyle , En-Hung Chao , Norman Christ , Ceran Hu , Luchang Jin , Yidi Zhao

We present a theoretical framework within which both the real and imaginary parts of the complex, two-photon exchange amplitude contributing to $K_L\rightarrow\mu^+\mu^-$ decay can be calculated using lattice QCD. The real part of this…

High Energy Physics - Phenomenology · Physics 2024-06-12 En-Hung Chao , Norman Christ

In this paper, for the first time a method is proposed to compute electromagnetic effects in hadronic processes using lattice simulations. The method can be applied, for example, to the leptonic and semileptonic decays of light or heavy…

High Energy Physics - Lattice · Physics 2015-06-23 N. Carrasco , V. Lubicz , G. Martinelli , C. T. Sachrajda , N. Tantalo , C. Tarantino , M. Testa

We demonstrate the lattice QCD calculation of the long distance contribution to $\epsilon_K$. Due to the singular, short-distance structure of $\epsilon_K$, we must perform a short-distance subtraction and introduce a corresponding…

High Energy Physics - Lattice · Physics 2016-11-22 Ziyuan Bai

We present a non-perturbative lattice calculation of the form factors which contribute to the amplitudes for the radiative decays $P\to \ell \bar \nu_\ell \gamma$, where $P$ is a pseudoscalar meson and $\ell$ is a charged lepton. Together…

High Energy Physics - Lattice · Physics 2021-01-13 A. Desiderio , R. Frezzotti , M. Garofalo , D. Giusti , M. Hansen , V. Lubicz , G. Martinelli , C. T. Sachrajda , F. Sanfilippo , S. Simula , N. Tantalo

We present a preliminary non-perturbative lattice calculation of the form factors entering the processes $K\to \ell\,\nu_\ell\,\ell'^+\,\ell'^-$ and of the corresponding branching ratios. These form factors describe the interaction between…

High Energy Physics - Lattice · Physics 2022-01-12 R. Frezzotti , G. Gagliardi , V. Lubicz , G. Martinelli , F. Mazzetti , C. Sachrajda , F. Sanfilippo , S. Simula , N. Tantalo
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