Kaon International Conference

May 21, 2007, 8:00 AM → May 25, 2007, 6:00 PM Europe/Rome

High Energy Building - Aula Bruno Touschek (Laboratori Nazionali di Frascati dell'INFN)

The Conference follows former editions with similar emphasis on kaon physics, aiming at a comprehensive discussion on the latest experimental and theoretical achievements, including precision tests of the SM, study of non-perturbative QCD, improvements in CP and CPT tests, development of new projects sensitive to physics beyond the SM.

Monday, May 21

Welcome and Overview

1 Welcome

Speaker: Maria Curatolo (LNF INFN, Frascati)

Slides kaon07welcome.ppt

2 Opening

Speaker: Prof. Paolo Franzini (Rome University, "La Sapienza")

Slides kaon07franzini.pdf

3 Implications of CKM Unitarity

Speaker: Prof. William J. Marciano (Brookhaven National Laboratory)

Slides Bill-kaon07i.pdf

11:30 AM Coffee Break

4 Flavour physics and the role of Kaons

Speaker: Luca Silvestrini (Rome University, "La Sapienza")

Slides silvestrini@kaon.pdf

5 How well do we know the Unitary Triangle? An experimental overview

Substantial progress has been recently made in the measurement of the CKM matrix parameters Rho and Eta that define the so-called Unitarity Triangle. In this presentation I will review the latest experimental results in this field coming from the study of both B and kaon decays. These precise and redundant measurements not only determine parameters of the Standard Model but also allows us to set constraints on New Physics.

Speaker: Prof. Gabriella Sciolla (MIT)

Slides Kaon2007-sciolla.pdf

6 Highlights from new physics searches in Heavy Flavour Experiments

The present status of new physics searches in flavour experiments is reviewed. Measurements that indicate possible deviations from the standard model are listed, with a special emphasis on results from two B-factories. Prospects for future experiments are also mentioned briefly.

Speaker: Prof. Masashi Hazumi (KEK, Tsukuba)

Slides hazumi_kaon07.ppt

1:20 PM Lunch

Session I: Vus

Conveners: Juliet Lee-Franzini (LNF-INFN, Frascati), Matthew Moulson (LNF-INFN, Frascati)

7 Precision tests of the SM with Kl3 decays

Speaker: Dr Vincenzo Cirigliano (Los Alamos)

Slides vincenzo_cirigliano_21.pdf

8 Vus from tau decays

Speaker: Prof. Antonio Pich (Valencia University, IFIC)

Slides pich_Vus_tau_Kaon07.pdf

9 Hadronic tau decays from BABAR & BELLE: measurement of |Vus|

We report measurements of branching fractions for several hadronic tau decays to final states including kaons, which can be used to determine the strange quark mass and the element |Vus| of the CKM quark mixing matrix. The results are collected with the Babar detector at PEP-II, the SLAC asymmetric-energy e+e- collider.

Speaker: Swagato Banerjee (University of Victoria)

Slides Talk.pdf

10 K to pi semileptonic form factor on the lattice with 2+1 flavor Domain Wall Fermions

We present the latest results from UKQCD/RBC collaborations for the Kl3 form factor with 2+1 flavours of dynamical domain wall quarks. Simulations are performed on 16^3x32x16 and 24^3x64x16 lattices with three values of the light quark mass, allowing for an extrapolation to the chiral limit

Speaker: Andreas Juettner (Univ. of Southampton)

Slides juettner_21.pdf

11 Charged kaon semileptonic decays and their ratio at the NA48/2 experiment; K0_{mu3} form factors at NA48 experiment

Measured ratios of decay rates for ${\cal R}_{K e 3 / K2\pi}$, ${\cal R}_{K \mu 3 / K2\pi}$ and ${\cal R}_{K \mu 3 / Ke3}$ are presented, based on $K^\pm$ decays collected in a dedicated run in 2003 by the NA48/2 experiment at CERN. The results obtained are $ {\cal R}_{K e 3 / K2\pi} = 0.2470\pm 0.0009 (stat)\pm 0.0004 (syst)$ and $ {\cal R}_{K \mu 3 / K2\pi} = 0.1637\pm 0.0006 (stat)\pm 0.0003 (syst)$. Using the PDG average for the $K^\pm \rightarrow\pi^\pm \pi^0$ normalisation mode, both values are found to be larger than the current values given by the Particle Data Book and lead to a larger magnitude of the $|V_{us}|$ CKM element than previously accepted. When combined with the latest Particle Data Book value of $|V_{ud}|$, the result is in agreement with unitarity of the CKM matrix. In addition, a new measured value of $ {\cal R}_{K \mu 3 / K2\pi} = 0.663\pm 0.003(stat)\pm 0.001(syst)$ is compared to the semi-empirical predictions based on the latest form factor measurements. The Kmu3 form factors have been measured from a sample of $K_L$ decays in a dedicated run in 1999 by the NA48 experiment at CERN. Studying the Dalitz plot density, using the linear form factor approximation, a measurement was made of $\lambda_+=26.7\pm0.6_{stat}\pm0.8_{sys}\times 10^-3$ and $\lambda_0=11.7\pm0.7_{stat}\pm1.0_{sys}\times 10^-3$. Measurements were also made using the quadratic parameterisation, the pole parameterisation and the dispersive parameterisation. The results of all parameterisations will be presented.

Speaker: Ms Anne Dabrowski (Department of Physics and Astronomy, Northwestern University)

Slides Kaon_vus_2007.ppt

4:40 PM Coffee break

12 Dispersive representation and shape of K_{l3} form factors.

In this talk we will introduce an accurate dispersive parametrization of the two K_{l3} form factors and discuss three applications to the analysis of K_{e3} and K_{mu3} measurements: the prediction of the branching ratios K_{mu3}/K_{e3}, the extraction of |f_+(0)V_{us}| and finally the possible measurement of m_d - m_u induced isospin breaking asymmetry.

Speaker: Emilie Passemar (IPN Orsay)

Slides PassemarKaons07.pdf

13 Did one observe couplings of right - handed quarks to W?

The recent dedicated analysis of K^L_{$\mu$ 3} Dalitz plot by NA48 reveals a 5 $\sigma$ deviation from the Callan-Treiman low-energy theorem , provided standard electroweak couplings of quarks are assumed. QCD can hardly tolerate such a huge violation of its $ SU(2) X SU(2) $ chiral symmetry. We suggest that , instead, the observed discrepancy reflects a small admixture of right - handed quark currents coupled to W ( as proposed by us one year ago.) It is argued that this interpretation allows to explain the observeed size of the effect and passes all electroweak tests at sub-TeV scales , both in the charged and in the neutral currents sectors. The possible impact on the tests of CKM unitarity for light quarks will be briefly discussed.

Speaker: Jan Stern (IPN Orsay)

Slides SternKaon07.pdf

14 KLOE measurement of the charged kaon absolute semileptonic BR's

The semileptonic BR's are relevant for the evaluation of the CKM matrix element |Vus|. The measurement of the branching ratios for the charged K semileptonic decays uses four independent samples tagged by the following kaon decays: K+ -> mu2, K+ -> pi2, K- -> mu2, and K- -> pi2. Using 410 pb-1 of total integrated luminosity (2.5 fb-1), about 60 million tag decays have been identified and divided into the four tag samples. This redundancy allows to keep under control the systematic effects due to the tag selection. The BR is evaluated separately for each tag sample, dividing by the number of tag counts and correcting for acceptances. The latter are obtained from MC simulations. Corrections are applied to account for data-MC differences in tracking and clustering. K+-e3 and K+-mu3 decays are selected, using kinematical cuts in the kaon rest frame and time of flight particle identification. The measurement of these BR's will be presented.

Speaker: Dr Barbara Sciascia (LNF - INFN, Frascati)

Slides Kaon07_sciascia.pdf

15 Measurement of Ke3 branching ratio and study of K to mu nu gamma decay at ISTRA+ setup

We review recent results on charged kaon decays obtained by ISTRA+ collaboration. The obtained branching fractions are compared with theoretical predictions. For Kl3 radiative decays the estimations of T-odd asymmetry are given.

Speaker: Mr Viacheslav Duk (INR RAS)

Slides kaon07_duk.ppt

16 KLOE measurement of form factor slopes for K_L to pi l nu decays.

Semileptonic kaon decays offer possibly the cleanest way to obtain an accurate value of the Cabibbo angle, or better, $V_{us}$. At present, the largest uncertainty in calculating $V_{us}$ from the decay rate, is due to the difficulties in computing the matrix element of the $K \rightarrow \pi$ transition. The matrix element of $K_L \rightarrow \pi \mu \nu$ decay is expressed in terms of kaon and pion four-momenta, $P$ and $p$ respectively, and using form factors $f_+(t)$ and $f_0(t)$, where $t=(P-p)^2$. It is customary to expand the scalar form factor $f_0(t)$ in powers of $t$ as $f_0(t)=f_+(0)\left[1+\lambda_0^{\prime} t/m^2+..\right]$, where $m$ is the mass of the carged pion, and only the linear term is retained. The form factor at zero momentum transfer, $f_+(0)$, is evaluated from theory, while the form factor slope, $\lambda_0^{\prime}$, has to be determined experimentally from $K_L \rightarrow \pi \mu \nu$ decay spectra. The best sensitivity to $\lambda_0^{\prime}$ is achieved in KLOE by using the neutrino energy spectrum. Such a measurement is possible because of the tagging technique, consisting of identifying $K_L$ decays through the selection of $K_S \rightarrow \pi^+\pi^-$ decay near the $e^+ e^-$ interaction point. This strategy allows to measure $K_L$ momentum with good precision. We present the results of this analysis, based on 330 pb$^{-1}$ of data acquired during years 2001 and 2002.

Speaker: Dr Claudio Gatti (LNF - INFN, Frascati)

Slides kaon07_gatti.pdf

17 KLOE measurements of the charged Kaon lifetime and BR(K+ into pi+ pi0)

The charged K lifetime, is an experimental input to the determination of Vus. The present fractional uncertainty is about 0.2%, however the available data show large discrepancies between the measurements done using charged kaon decays in-flight and at-rest. At KLOE two different methods have been developed: one based on the measurement of the charged kaon decay length and the other based on its decay time. Both methods allow us to reach accuracies at the few per mil level. These two independent methods allow us to assess part of the systematic uncertainty. Efficiency and resolution functions are measured directly on data using an independent control sample. The measurement of the charged kaon lifetime will be presented. A new precise measurement of the absolute BR(K+ -> pi pi0 (gamma)) has an important impact on the world average of the charged kaon semileptonic BR's, because of the NA48, ISTRA+ and E865 experiments that use the pi pi0 decay in the normalization sample. A pure K+ beam is tagged at KLOE by the recostruction of the K- -> mu nu decays. The signal counting is given by a fit to the distribution of the momentum of the charged decay particle in the kaon rest frame assuming the pion mass. The shapes of the signal and of the backgrond (mu nu and 3 bodies decays) are obtained from data control samples and MC. Efficiency is measured directly on data using an independent control sample. The measurement of the BR(K+ -> pi pi0 (gamma)) will be presented.

Speaker: Paolo Massarotti (Naples University & INFN)

Slides Kaon_Massarotti_07.ppt

7:30 PM Welcome Party at Villa Grazioli

Tuesday, May 22

Session I: Vus and Vud

Convener: Mario Antonelli (LNF-INFN, Frascati)

18 Theoretical progress on Vus on Lattice

Speaker: Prof. Takashi Kaneko (KEK, Tsukuba)

Slides takashi_kaneko_22.pdf

19 Determination of Vud - Overview

Speaker: Dr Takeyasu Ito (Los Alamos)

Slides takeyasu_ito_22v3.pdf

20 Experimental Review on Vus extraction from Kaon decays

At present, the first-row constraint, $|V_{ud}|^2 + |V_{us}|^2 + |V_{ub}|^2$ = 1 (with $|V_{ub}|^2$ negligible), offers the most precise test of CKM unitarity. Up until 2002 (and for the 2004 PDG evaluation), the evaluation of $|V_{us}$ from older $K_{l3}$ data gave 2.3$\sigma$ hint of unitarity violation in the first-row test. The 2003 measurement of BR($K^+_{e2}$) by BNL E865 gave a value for $|V_{us}|$ consistent with unitarity. In the period 2004-2006, many new measurements of BRs, lifetimes, and form-factor slopes were announced by KLOE, KTeV, ISTRA+ and NA48. All of these new measurements are distinguished from the older measurements in that they are based on much higher statistics, and in that radiative corrections are applied consistently. The 2006 PDG review on $|V_{us}$ includes many, but not all, of these important developments. I will present an up-to-date evaluation that includes preliminary results presented at this conference.

Speaker: Dr Matteo Palutan (LNF -INFN)

Slides palutan.pdf

10:30 AM Coffee Break

Session II: CP and T violation

Convener: Johan Bijnens (Lund Univ.)

21 Lattice progress on non-leptonic decays

The precise evaluation of K to pi pi decay amplitudes is one of the most important goals and milestones for Lattice QCD and an area of particle physics where lattice simulations can make a very significant impact. I will review recent theoretical progress (including the so-called "infrared problem"), the current status of the numerical results and the prospects for future developments.

Speaker: Prof. Christopher Sachrajda (Southampton University)

Slides kaon2007.pdf

22 ChPT progress on non-leptonic and radiative decays

I discuss selected topics on non-leptonic and radiative kaon decays mainly related to direct CP-violation within the combined ChPT and large N_c approaches.

Speaker: Prof. Joaquim Prades (Granada University)

Slides prades_kaon07.pdf

23 Lattice progress on epsilon-prime

Speaker: Prof. Robert Mawhinney (Columbia University)

Slides talk.pdf

24 Measurement of the CP violation parameter $|\eta_{+-}|$ and the charge asymmetry in $K^\pm \to 3\pi$ decays by NA48 and NA48/2

The main goal of the NA48 experiment at the CERN SPS has been the search for direct CP violation (CPV) in kaon decays. The observable $\eta_{+-}$ is related to the parameters of indirect and direct CPV ($\eta_{+-} = \varepsilon + \varepsilon^\prime$) and defined as the CP violating amplitude ratio of the neutral kaon decaying into two charged pions: $\eta_{+-} = A(K_L \to \pi^+\pi^-)/A(K_S \to \pi^+\pi^-)$. NA48 has determined $|\eta_{+-}|$ via the measurement of the ratio of decay rates $\Gamma(K_L \to \pi^+\pi^-)/\Gamma(K_L \to \pi e \nu)$. The data were taken during a dedicated run in 1999 using a pure $K_L$ beam. The analysis is based on 47000 $K_L \to \pi^+\pi^-$ and five million $K_L \to \pi e \nu$ decays. Complementary with $\varepsilon^\prime/\varepsilon$, the observable in the charged kaons sector is the asymmetry $A_g = (g^+ - g^-)/(g^+ + g^-)$ of the linear slope parameter $g$ in the Dalitz plot of $K^\pm \to 3\pi$ decays. Any non-zero value of $A_g$ would reflect evidence for direct CPV. SM predictions for the charge asymmetry give an upper limit of a few $10^{-5}$, while theoretical calculations involving processes beyond the SM do not exclude substantial enhancements of $A_g$. The NA48/2 experiment used simultaneous $K^+/K^-$ beams, and from the data samples taken in 2003 and 2004, $3.11 \times 10^9 K^\pm \to \pi^\pm\pi^+\pi^-$ and $9.13 \times 10^7 K^\pm \to \pi^\pm\pi^0\pi^0$ were selected. The charge asymmetry parameter $A_g$ was determined with a total uncertainty of $\sim 2\times 10^{-4}$ for each mode, ten times more accurate than previous measurements.

Speaker: Dr Andreas Winhart (Institut fuer Physik, Universitaet Mainz)

Slides andreas_winhart_22.pdf.pdf

25 A new $ K^{0}_{L} $ decay channel

The rate for the decay $ K^{0}_{L} \Rightarrow K^{\pm} e^{\mp}(\overline {\nu}/\nu) $ of (0.0979 $\pm 0.0037 $) $ s^{-1} $ has been calculated in the hypothesis of the conserved vector current and , assuming the CP violation very small , the two rates for the decay $\overline{ K^{0}_{L}}\Rightarrow K^{-} e^{+} \nu $ and $ K^{0}_{L} \Rightarrow K^{+} e^{-} \overline {\nu} $ are foreseen very similar. Such a decay was never taken into account in the past , due to the very low phase space factor yielding a branching ratio for $ K_{L} $ decay BR= $(0.5071\pm 0.0199) \times 10^{-8} $. Now , with the very intense $ K $ beams foreseen at KEK , J-PARC, BNL , CERN and LNF the observation of this decay seems feasible. With samples of very large statistical significance a new measurement of the indirect CP violation parameter $\epsilon$ could be done.

Speaker: Prof. Antonino Pullia (Universita` di Milano Bicocca and INFN)

Slides antonino_pullia_22.ppt

26 Measurement of T-violating transverse muon polarization in $K^+ \rightarrow \pi^0 \mu^+ \nu$ decay at J-PARC

As a precision frontier experiment at J-PARC, we proposed a search for time reversal invariance violation by measuring the transverse muon polarization (Pt) in the $K^+ \rightarrow \pi^0 \mu^+ \nu$ (Kmu3) decay which constitutes a T-odd observable. This observable is one of the few test of T-invariance and the corresponding CP violation in non-neutral meson sector and is sensitive to direct CP violation. At J-PARC, we aim to improve the precision of the measurement by a factor of 20 comparing with the best result from our own KEK-PS E246 experiment, and reach a limit of $\Delta$Pt$\sim10^{-4}$. The final state interaction contributions in the SM descriptions are significantly smaller than the sensitivity of this experiment. On the other hand, several exotic models inspired by Multi-Higgs mechanism etc. predict sizable Pt values within the sensitivity attainable to us. Thus, this experiment is likely to find new source of CP violation, if any of these models are viable. Since it will certainly constrain the parameter space of the candidate models, the sensitivity of this experiment is comparable or superior to that of the proposed new neutron EDM experiment and other rare decay processes. The physics potential in terms of discovery of new physics along with the power to constrain the exotic model is shown to be competitive with other experiments being planned or prepared. It is pointed out that the improved sensitivity will be achieved thanks to the new J-PARC facility beam quantities, namely, the newly designed low-momentum $K^+$ beam line. The experiments will use a stopped $K^+$ beam in conjunction with the upgraded E246 setup. Major changes of the detector system are 1) improved charged particle tracking by incorporating the sate-of-art GEM detectors, 2) new readout of the CsI(Tl) calorimeter with APD, 3) introducing active polarimeter for the e+ measurement from muon, and 4) a new magnet to hold the muon spin polarization. This arrangement with increased $K^+$ beam intensity and a runtime of $10^7$ seconds will improve the E246 result by a factor of 20, bringing the discovery potential to $\Delta$Pt$\sim10^{-4}$ in our quest for new physics.

Speaker: Dr Suguru Shimizu (Osaka University)

Slides kaon07_shimizu.ppt

1:20 PM Lunch

Session II: Radiative Decays

Convener: Giancarlo D'Ambrosio (Naples Univ. and INFN)

27 Radiative and semileptonic decays in Chiral Perturbation Theory

I will give an overview of the recent results in ChPT relevant for kaon physics including K_l3 and K_l4 at two-loop order.

Speaker: Prof. Johan Bijnens (Lund University)

Slides bijnens_57.pdf

28 New precise measurements of radiative charged kaon and hyperon decays

The NA48/2-Experiment at the CERN SPS has recorded more than 2 billion charged kaon decays. From a sub-sample of this data set we have selected about 2 x 10^5 practically background free events of the decay K+- -> pi+- pi0 gamma, which is an order of magnitude more than from any previous experiment. The decay K+- -> pi+- pi0 gamma is dominated by Inner Bremsstrahlung (IB) of the K+- -> pi+- pi0 decay, but also exhibits a contribution of Direct Emission (DE), which is of high theoretical interest, as well as the interference between both amplitudes. We present a precise measurement of both the DE amplitude and the interference between IB and DE. In addition, using the full data set, we have made the first observation of the very rare decay K+- -> pi+- gamma e+ e-, which has large contributions from higher order pion loops. We have measured the branching fraction and the form factor of this decay. Finally, from 2002 data set the weak radiative decay Xi0 -> Lambda e+ e-has been detected for the first time. From 412 candidates in the signal region, with an estimated background of 15 events, the branching ratio is measured and is consistent with an internal bremsstrahlung process. The decay asymmetry parameter is also determined, consistent with that of Xi0 -->Lambda gamma which has been measured as well.

Speaker: Dr Ermanno Imbergamo (Universita' di Perugia)

Slides kaon2007_ei.ppt

29 Study of K^(-) into e,nu,pi^(0),gamma decay with ISTRA setup

Results of study of the negative kaon into electron,neutrino, neutral pion, gamma decay at ISTRA setup are presented. 4476 events of this decay have been observed. The branching ratio to be Br=(3,06+- 0.09+-0.14)x10^(-4) for E>30 MeV and theta>20deg. For the asymmetry A=-0.015+-0.021. At present it is the best estimate of the asymmetry.

Speaker: Prof. Vladimir Bolotov (Institute for Nuclear Research of RAS)

Slides Report_K-P0eng-bolotov.ppt

30 KLOE measurement of $BR(K_L \rightarrow \pi e \nu \gamma)$.

The study of radiative $K_L$ decays offers the possibility to obtain informations on kaon structure and to test predictions of the Chiral Perturbation Theory. Two different processes contribute to photon emission in $K_L \rightarrow \pi e \nu \gamma$ decay ($K_{Le3\gamma}$): the inner bremsstrahlung (IB) and the direct emission (DE). The latter is due to photon radiation from intermediate hadronic states. To compare with theoretical predictions and present best experimental results, we measured the ratio $R = BR(K_{Le3\gamma}; E^{\ast} > 30 {\rm MeV}, \theta^*>20^{\circ}) /BR(K_{Le3})$, where $E^{\ast}$ and $\theta^{\ast}_{e\gamma}$ are the photon energy and the angle between electron and photon in $K_L$ rest frame, respectively. With these cuts the theoretical predictions for $R$ range between 0.95\% and 0.99\% . The DE contribution is expected to be less than 1\% of IB one. KLOE measurement benefits of the tagging technique, which consists of identifying $K_L$ decays through the selection of $K_S \rightarrow \pi^+\pi^-$ decay near the $e^+e^-$ interaction point. This strategy allows to achieve an optimal background rejection, and also to measure $K_L$ momentum with good precision. We present the results of this analysis, based on 330 pb$^{-1}$ of data acquired during years 2001 and 2002.

Speaker: Dr Marco Dreucci (LNF- INFN)

Slides dreucci_kaon@ke3g11.pdf

31 Radiative decay results from KTeV

The KteV experiment has carried out a broad program of studies of rare kaon decays. In this talk we present results on KL-> pi0 gamma gamma, KL-> pi0 e+ e- gamma and KL-> pi+ e- nu e+ e- . These decays provide a window for testing chiral perurbation theory at O(p^6). We find BR(KL-> pi0 pi0 gamma)= (1.30 +/- 0.03 +/- 0.04)E-6, BR(KL-> pi0 e+ e- gamma)= (1.9 +/- 0.16 +/- 0.12)E-8, and BR(KL-> pi+ e- nu e+ e-)= (1.281 +/- 0.041)E-5. The KTeV measurements are competitive with or better than the world's best results in these decays.

Speaker: Prof. Elliott Cheu (Arizona University)

Slides elliott_cheu_22.pdf.pdf

32 KLOE measurements of the BR(Ks into gamma gamma) and direct search for Ks into e+e-

A precise measurement of the $K_S \rightarrow \gamma \gamma$ rate is an important test of Chiral Perturbation Theory predictions. The decay amplitude can be evaluated at the leading $p^4$ order providing an estimate of the $BR$ for this decay of $(2.1\pm0.1)\times10^{-6}$. The latest experimental determination of $BR(K_S \rightarrow \gamma \gamma)$ is a precise measurement from NA48, $(2.78\pm0.07)\times 10^{-6}$, which differs from $\chi$PT $p^4$ prediction of about 30\%. This seems to indicate the presence of important contributions from higher order corrections. KLOE analysis on 1.6 fb$^{-1}$ of data acquired during years 2001-2002 and 2004-2005 benefits from the tagging technique, which allows for the first time this decay to be identified with a pure $K_S$ ``beam'', without the background from $K_L \rightarrow \gamma \gamma$ decay, and with completely different systematics respect to fixed target experiments. Event counting is performed from a fit to the bidimensional distribution of the two-photon invariant mass versus the angle between photon momenta in the $K_S$ rest frame. In this plane the best separation is achieved between the signal and the main source of background, which is represented by $K_S \rightarrow \pi^0 \pi^0$ events with two missing photons. The result of this analysis is presented, which is competitive with present measurements. $K_S \rightarrow e^+e^-$ decay is a $\Delta S = 1$ weak neutral current process. The Standard Model expectation for its $BR$ is $1.6\times10^{-15}$, which has been evaluated by Chiral Perturbation Theory with 10\% error. The best experimental limit on this decay, achieved by CPLEAR experiment, is $BR < 1.4\times10^{-7}$ at 90\% CL. We performed a direct search of $K_S\rightarrow e^+e^-$ decay by analysing 1.3 fb$^{-1}$ of data. The analysis exploits the excellent KLOE drift chamber momentum resolution to identify the signal through $e^+e^-$ invariant mass reconstruction. Further background rejection comes from calorimeter particle identification, which is based on time of flight, shower longitudinal profile and $E/p$. The result of this search is presented, which improves on the previous experimental limit by a factor of 10.

Speaker: Dr Matteo Martini (LNF -INFN)

Slides matteo_martini_22.ppt

4:30 PM Coffee Break

Lepton Universality

33 Experimental Review and future prospects on pie2 measurements

Speaker: Prof. Douglas A. Bryman (TRIUMF and British Columbia University)

Paper bryman_pie2_kaon07_v2.pdf

Slides Bryman_pienu_kaon07.pdf Bryman_pienu_kaon07.ppt

Session III: Low Energy QCD

Convener: Gilberto Colangelo (Bern Univ.)

34 Theoretical progress on cusp effect and Kl4

Data on hadronic reactions have become so precise by now that one has to take into account radiative corrections as completely as possible. My talk will concentrate on this issue from a theoretical point of view, for K->3 pi and K_e4 decays.

Speaker: Prof. Juerg Gasser (Berna University)

Slides KAON07_gasser.pdf

35 Precision study of K+- into pi+- pi0 pi0 and K+- into pi+- pi+ pi- Dalitz plot distributions by NA48/2.

The NA48/2 experiment at the CERN SPS has collected an unprecedented sample of 3-pion decays of charged kaons. The high statistics and the good resolution of the detectors allow a unique investigation of the detailed phase space distributions of these decays. The effects of final state pion rescattering observed in the Dalitz plot distribution of the K+- into pi+- pi0 pi0 decays turned out to be a powerful tool for extraction of the S-wave pion-pion scattering lengths. The recent results obtained using a number of different theoretical approaches will be discussed, together with future prospects. The large statistics also allowed a precise measurement of the Dalitz plot slope parameters for the K+- into pi+- pi+ pi- decays, which will be discussed.

Speaker: Dr Evgueni Goudzovski (Scuola Normale Superiore and INFN, Pisa)

Slides goudzovski_kaon2007.ppt

36 Recent results from NA48/2 on Ke4 decays and interpretation in term of pi-pi scattering lengths

The NA48/2 experiment at the CERN SPS has collected about 10**6 K± decays into pi+ pi- e± ν (Ke4) in 2003 and 2004. The analysis of a partial sample of ~500000 such events allows a precise measurement of the decay parameters. The form factors of the reaction and their dependence with dipion and dilepton masses have been measured. Thanks to a sizeable acceptance at large Mpipi and the very good resolution of the NA48 detector, a high sensitivity to the pi-pi scattering lengths a00 and a02 is achieved. These almost model independent measurements can be confronted with the predictions from different calculations, in particular within the framework of Chiral Perturbation Theory.

Speaker: Mrs Brigitte BLOCH-DEVAUX (DAPNIA/SPP CEA-SACLAY ( FRANCE))

Slides bbloch_22.pdf

37 An update of the DIRAC result on the pion-pion |a0-a2| scattering length

DIRAC aims at measuring the scattering length |a0-a2| through the lifetime of the pi+pi- atom in its 1S state. The published result (Physics Letters B 619 (2005)) used only part of the totally collected statistics. An update of the result concerning the statistical accuracy will be presented.

Speaker: Prof. Ludwig Tauscher (Basel University)

Slides tauscher_ludwig_22.58.pdf

38 Kaonic X-ray experiments at DAFNE using SIDDHARTA

At the DAFNE electron-positron collider of Laboratori Nazionali di Frascati we study kaonic atoms, taking advantage of the low-energy kaons produced in the phi-meson decay. The kaon-nucleon interaction at rest in kaonic hydrogen and kaonic deuterium can be investigated under favorable conditions. The DEAR (DAFNE Exotic Atom Research) experiment at LNF delivered the most precise data on kaonic hydrogen up to now. DEAR and its follow-up experiment SIDDHARTA (Silicon Drift Detector for Hadronic Atom Research by Timing Application) are using X-ray spectroscopy of kaonic atoms to measure the strong interaction induced shift and width of the ground state. From these quantities the isospin-dependent antikaon-nucleon scattering lengths can be determined, quantities useful to test the understanding of chiral symmetry breaking in the strangeness sector. Within the SIDDHARTA project new X-ray detectors are being developed. We will use an array of large area silicon drift detectors (SDDs) having excellent energy resolution but also providing timing capability which will result in a huge suppression of background and so overcome the precision limits of the former experiments. With this experimental technique the measurement of kaonic deuterium X-rays will be feasible for the first time.

Speaker: Michael Cargnelli (Austrian Academy of Sciences - Stefan Meyer Institute)

Slides michael_cargnelli_22.ppt.ppt

Wednesday, May 23

Session III: Low Energy QCD

Convener: Juerg Gasser (Bern Univ.)

39 Theoretical progress on pi-pi scattering lengths and phases

Speaker: Prof. Gilberto Colangelo (Berna University)

Slides a0_a2.pdf

40 Review of pi-pi scattering measurements in K decays

Over the last few years it has become possible to study low energy ππ scattering in K decays to three pions, thanks to the high statistics measurement of K±→ π±π°π° decay with excellent π°π° invariant mass resolution performed by the NA48/2 experiment at the CERN SPS. The information on the ππ scattering lengths which can be extracted from these results is reviewed and compared with the results from studies of Ke4 decays, which include recent NA48/2 measurements. The possibility of studying ππ scattering in K±→ π±π+π− and KL→ π°π°π° decays is also discussed.

Speaker: Prof. Luigi Di Lella (Scuola Normale Superiore di Pisa)

Slides k2007_dilella.ppt

Session IV: CPT and QM tests

41 Review on Bell-Steinberger relation

Speaker: Dr Giancarlo D'Ambrosio (INFN, Naples)

Slides giancarlo_dambrosio_23.pdf

42 Review on CPT and decoherence measurements with Kaons

Neutral kaons provide one of the most sensitive systems to quantum mechanics and CPT violation. In the first part of the talk, I will review results on CPT violation searches in the kaon system from the CPLEAR, KLOE and KTeV experiments. In the second part I will present tests of quantum coherence related to CPT violation performed at CPLEAR and KLOE by studying the time evolution of the kaon system. The results show no deviations from the expectations of quantum mechanics and CPT symmetry and the accuracy reaches the interesting region of the Planck's scale. I will conclude showing the perspectives on CPT and quantum mechanics tests at a future high-luminosity phi-factory.

Speaker: Dr Marianna Testa (Rome Univ., "La Sapienza")

Slides Marianna_Testa.ppt

11:00 AM Coffee Break

43 Local Realism vs Quantum Mechanics with Entangled Neutral Kaons

We review recent proposals of Bell's inequality tests with entangled pairs of neutral kaons from $phi$ resonance decays. The suggested experiments are discussed in the light of the essential requirements for a genuine discrimination between Local Hidden-Variable Theories (i.e., Local Realism) and Quantum Mechanics. After showing that the tests proposed up to now can hardly (or cannot) be performed under conditions which are strictly free from the locality and the detection loopholes, we concentrate on those proposals which appear to be more feasible, clarifying their logical limitations in refuting the whole class of Local Realistic models.

Speaker: Dr Gianni Garbarino (Universita di Torino)

Slides garbarino_23.pdf

44 Erasing the Past and Impacting the Future with Kaons at a Phi-factory

Two hundred years ago Thomas Young taught us that photons interfere. Nowadays also experiments with very massive particles, like the fullerenes, have impressively demonstrated that fundamental feature of quantum mechanics. Later studies have shown that the knowledge on the path through the double slit is the reason why interference is lost. The gedanken experiment of Scully and Druehl in 1982 surprised the physics community, if the knowledge on the path of the particle is erased, interference is brought back again. We first show two setups of a kaonic quantum eraser which are conceptually analog to performed photon experiments. However, for kaons we have two more setups which are only provided by this quantum system. These new possibilities prove in a new way the very concept of an eraser and moreover are testable at DAFNE.

Speaker: Dr Beatrix Hiesmayr (Vienna University)

Slides Kaon07_Hiesmayr.ppt

45 EPR entanglement and decoherence in Upsilon(4S) decays to B0-B0bar

The neutral B-meson pair produced at Upsilon(4S) exhibits a non-local EPR-type entanglement. At Belle experiment at KEK, we measure this entanglement using time-dependent flavour asymmetry of semileptonic B0 decays and compare with prediction of quantum mechanics and two realistic models. We also measure the decoherence of the neutral B-meson pair in B0-B0bar and BH-BL basis.

Speaker: Dr Apollo Go (National Central University of Taiwan)

Slides 0705_EPR_Decoherence_-_Frascati.ppt

12:50 PM Lunch

2:00 PM Excursion to Rome with visit to the Borghese Gallery

Thursday, May 24

Session IV: CPT and QM tests

46 CPT and Decoherence in Quantum Gravity

I will give an overview of theoretical reasons for expecting a possible violation of CPT symmetry in some models of Quantum Gravity and then I will proceed to discuss experimental signatures of such a violation. As CPT violation may be (but not necessarily) linked to Lorentz Invariance Violation (LIV), a seizable portion of the talk will be devoted to tests of Lorentz symmetry violations, with emphasis on the case of neutral Kaons, which is of direct relevance to this conference. In the second part of the talk, I will discuss tests for CPT violation due to decoherence in some quantum gravity models, and I will explain how the latter can be disentangled from other effects, such as LIV. In this respect, I will describe some possibly unique (if exist) signatures of CPT violation through decoherence in entangled states of neutral mesons, produced at meson (such as Phi- or B-) factories, and I will discuss briefly the relevant tests and sensitivities, including some theoretical estimates on the order of magnitudes of such effects.

Speaker: Prof. Nikolaos Mavromatos (King's College, London)

Slides nikolaos_mavromatos_23.pdf nikolaos_mavromatos_23.ppt

Session V: Lepton Universality and LFV

47 Theoretical Review on Lepton Universality and LFV

Speaker: Dr Paride Paradisi (Valencia University, IFIC)

Slides paradisikaon07.pdf

48 Kaon physics within nuMSM

An extension of the Standard Model by three singlet fermions with masses smaller than the electroweak scale allows to explain simultaneously neutrino oscillations, dark matter and baryon asymmetry of the Universe. We discuss here the properties of neutral leptons in this model and the ways they can be searched for in particle physics experiments. In particular, if sterile neutrinos are lighter than kaons, they can be produced in leptonic and semileptonic kaon decays with branching ratios only one-two orders of magnitude below the current experimental limits from direct searches. This gives a unique possibility to either prove or rule out nuMSM with light sterile neutrinos.

Speaker: Dr Dmitry Gorbunov (INR RAS)

Slides NuMSM_Kaon07.pdf

49 LFV searches in Klong decays

Speaker: Prof. Robert Tschirhart (FNAL)

Slides Robert_Tschirhart_24_1.pdf Robert_Tschirhart_24_1.ppt

50 Probing the lepton flavour universality with Kl2

The ratio $R_K = \Gamma(K^{\pm}\to e^{\pm}\nu) / \Gamma(K^{\pm}\to \mu^{\pm}\nu) $ provides a very powerful probe for the weak interactions structure. This ratio of decay rates is calculated with very high precision within the Standard Model but corrections due to the presence of New Physics could be as high as 3\%. The data obtained by the NA48 experiment in two years of data taking at the CERN SPS accelerator has been analyzed. The obtained result for $R_K$ is two times more precise than the world average but is still insufficient to probe the existence of physics Beyond the Standard Model. A new run in 2007, aimed for a sub-percent precision measurement of $R_K$, has been proposed and approved.

Speaker: Venelin Kozhuharov (Univerity of Sofia "St. Kl. Ohridski")

Slides Venelin-kaon07.pdf

11:10 AM Coffee Break

51 Preliminary measurement of BR(ke2)/BR(kmu2) at KLOE

We present a preliminary measurement of the ratio of the purely leptonic branching ratios of the charged kaons, BR(ke2)/BR(kmu2), using a sample of about 2 fb-1 of data acquired with the KLOE detector at the Frascati \phi-factory DAFNE.

Speaker: Alexei Sibidanov (BINP, Novosibirsk)

Slides alexei_sibidanov_24.pdf

52 Lepton Universality Tests with Kaons

Precision data on Kl3 and Kl2 decay rates and form factors allow us to perform significant tests of lepton universality and to constrain the strength of non-standard interactions. We discuss the present status of these tests and new-physics searches, as obtained by combining all the available results of the various kaon-physics experiments

Speaker: Dr Rainer Wanke (Mainz University)

Slides Frascati_2007.pdf

53 Rare and forbidden decay of Charm Mesons at CLEO-c and BESIII

In this talk, I will give a brief review on the current limits of rare and forbidden decays of Charm mesons at CLEO-c and BES experiments. The current status of BES-III project as a tau-Charm factory will be discussed. The sensitivities of the measurements for rare and forbidden Charm decays are estimated. The test of Lepton Universality and LFV in J/psi decay at BES-III are also presented. Finally, I will discuss the measurement of neutral D meson mixing by using data at DDbar threshold at BES-III.

Speaker: Dr Haibo Li (IHEP, Beijing)

Slides Li_rare_charm.ppt

54 Experimental Review on Lepton Universality and LFV tests at a B-factory

Since 1999, the B-factory Collaborations, Babar and Belle, have accumulated and studied large samples of tau lepton pairs. The experimental results on Lepton Universality checks and Lepton Flavour Violation searches will be reported.

Speaker: Dr Alberto Lusiani (INFN - Pisa)

Slides lusiani-kaon07-3.pdf

1:20 PM Lunch

Panel for discussing experimental and theoretical prospects

Signals of new physics with experiments on flavor : relevance and progress of new initiatives.

55 Hints from theory

Speaker: Prof. Antonio Masiero (Padua University and INFN)

Slides KAON'07_masiero.pdf

56 Progress on tau/charm factory

Speaker: Dr Haibo Li (IHEP, Beijing)

Slides Li_BEPCII_status.ppt

57 Kaon physics at hadronic machines

Speaker: Augusto Ceccucci (CERN, Geneva)

Slides Augusto_Ceccucci_Panel.ppt

58 Fermilab program on flavor physics

Speaker: Robert Tschirhart (Fermilab, Batavia)

Slides R_Tschirhart_24.pdf R_Tschirhart_24.ppt

59 The J-PARC project

Speaker: Taku Yamanaka (Osaka University)

Slides yamanaka_kaon2007_jparc.pdf

4:15 PM Coffee Break

60 Progress on the design of next generation flavor factories

Speaker: Pantaleo Raimondi (LNF-INFN, Frascati)

Slides Flavour_factory_short.ppt

61 Physics at a high luminosity phi-factory

Speaker: Fabio Bossi (LNF-INFN, Frascati)

Slides Bossi_panel.ppt

62 Future perspective for the SuperB project

Speaker: Francesco Forti (Pisa University and INFN)

Slides FORTI_SuperB_Perspectives.ppt

63 The Japanese program for KEK-B/Belle upgrade

Speaker: Peter Krizan (Ljubljana Univ. and J. Stefan Institute)

Slides kaon07-krizan.pdf kaon07-krizan.ppt

5:45 PM Open Discussion

64 Closing remarks

Speaker: Taku Yamanaka (Osaka University)

Slides yamanaka_panel_closing.pdf

7:30 PM Social Dinner at the Pagnanelli Restaurant in Castel Gandolfo

Friday, May 25

Session VI: Rare decays

65 Theoretical Review on very rare kaon decays including comparison with B physics

Speaker: Dr Ulrich Haisch (Zurich University)

Slides kaon07.pdf

66 Beyond SM expectations from very rare Kaon decays

Rare decays dominated by one-loop electroweak dynamics offer a very powerful tool to investigate the flavour structure of physics beyond the Standard Model (SM). Among them, the kaon rare decays K+ into pi+ nu nubar and Klong into pi0 nu nubar play a privileged role because of their strong suppression within the SM and the high-level of accuracy achieved in their theoretical description. Thanks to the theoretical control recently achieved over their long-distance components, the rare decays Klong into pi0 e+ e- and Klong into pi0 mu+ mu- also exhibit good sensitivities allowing, in particular to probe helicity-suppressed effects in a very clean way. We illustrate how precise measurements of rare kaon decays can be used to discriminate among different models of New Physics, both within and beyond the Minimal Flavour Violation framework.

Speaker: Dr Cecilia Tarantino (Technical University of Munich)

Slides rarekaonNP_kaon07.pdf

67 Recent progress on supersymmetric effects in rare K decays

Supersymmetry offers one of the most attractive extensions of the Standard Model. Intensive searches for supersymmetric partners will soon start at the LHC. In that context, rare K decays will play an essential role, complementary to direct searches at colliders. Indeed, they allow us to study in an exceptionally clean way the flavor breaking structures. In the minimal supersymmetric extension of the SM (MSSM), these are completely arbitrary parameters (the so-called soft-breaking terms), related to the unknown supersymmetry breaking mechanism. Knowing them will therefore give us a glimpse of the physics at a still higher scale. This general statement will be explained and illustrated within recently studied scenarios[1,2]. For instance, in the MSSM at moderate tan(beta), both with or without the minimal flavor violation hypothesis, rare K decays (especially K --> pi nu nubar) are the most sensitive probe of the flavor-breaking in the up squark sector[1]. Also, combined studies of KL --> pi0 e+ e- and KL-->pi0 mu+mu- could provide clean evidence for the MSSM at large tan(beta)[2]. Finally, these two modes also allow for studies of R-parity violating effects[2]. [1] Isidori, Mescia, Paradisi, Smith, Trine, "Exploring the flavour structure of the MSSM with rare K decays", JHEP 0608 (2006) 064 [arXiv:hep-ph/0604074]. [2] Mescia, Smith, Trine, "KL --> pi0 e+ e- and KL --> pi0 mu+ mu-: A binary star on the stage of flavor physics", JHEP 0608 (2006) 088 [arXiv:hep-ph/0606081].

Speaker: Dr Christopher Smith (University of Bern)

Slides Smith.pdf

68 The $K^+\rightarrow\pi^+\nu\bar{\nu}$ experiment at CERN

The NA48/3-P326 proposal for an experiment to measure the branching ratio of the very rare kaon decay $K^+\rightarrow\pi^+\nu\bar{\nu}$ at the CERN SPS will be described. The proposed experiment aims to collect about 80 $K^+\rightarrow\pi^+\nu\bar{\nu}$ events with a 10\% of background in two years of data taking. The status of the project, the R\&D and the future perspectives for the experiment will be discussed.

Speaker: Dr Giuseppe Ruggiero (Scuola Normale Superiore, Pisa)

Slides kaon2007_giuseppe_ruggiero.ppt

11:10 AM Coffee Break

69 Recent Progress by the E391a Collaboration

We will provide a status report on the E391a experiment conducted at KEK. Following a brief introduction to the experiment, we will discuss several of the current analysis topics, with a focus on the Monte Carlo and Kaon-related backgrounds. Additionally, we will discuss a new method for estimating the photon veto inefficiency for some detectors using actual data that is well-suited for medium energy experiments.

Speaker: Mr Gabriel Perdue (The University of Chicago)

Slides Perdue_Gabriel_49.pdf

70 A search for KL-> pi0 nu nubar at KEK-PS E391a experiment

The rare decay KL-> pi0 nu nubar is a Flavor Changing Neutral Current process from strange to down quarks and its observation is new evidence for direct CP violation. Its irreducible theoretical uncertainty is very small and the decay is considered an ideal place to test the Standard Model and explore signs of new physics in quark flavor physics. KEK-PS E391a, performed at the KEK 12GeV proton synchrotron, is the first dedicated experiment to measure the branching fraction of this decay mode. The beam line is very narrow to set the constraints on the pi0 kinematics. The detector hermetically covers the decay region to reduce backgrounds from other decay modes with extra particles. We will report results of recent data analysis mainly for the second data set (Run-II). It was carried out from February to April in 2005 with several crucial upgrades in the detector. Background reductions and improvements to the sensitivity for KL-> pi0nunubar due to those upgrades of the detector are discussed.

Speaker: Mr Toshi Sumida (Dept. of Physics, Kyoto University)

Slides toshi_kaon07_sub.pdf

71 $K_L^0 \to \pi^0 \nu \overline{\nu}$ Experiment at J-PARC

J-PARC (Japan Proton Accelerator Research Complex), which intends to provide MW-class super-intense proton beam, is under construction. First slow-beam extraction at 30 GeV is scheduled on December, 2008. J-PARC-E14 experiment aims at first observation of the rare decay $K_L^0 \to \pi^0 \nu \overline{\nu}$ using intense $K_L^0$ beam. E14 reuses most of the detector and beam-line components for KEK-PS E391a with some necessary modifications and upgrades. Thus E14 can get ready in a shorter preparation period, and the first physics run is proposed in 2010 to Program Advisory Committee. In this contribution the strategy, plan and status of the $K_L^0 \to \pi^0 \nu \overline{\nu}$ experiment at J-PARC will be reported in detail.

Speaker: Dr Hiroaki Watanabe (KEK)

Slides KL-JPARC-n.ppt

72 A proposal to measure the rare decay $K_L /rightarrow /pi^0 /nu /nubar$ at IHEP (Protvino) 70 GeV proton accelerator

The talk is supposed to be an extended description of the experimental setup KLOD, a joint project of IHEP (Protvino), INR (Moscow), JINR (Dubna). Some prospects related to this project have been preliminary reported at K-Rare2005 Workshop, Frascati. Presented at Kaon-2007 results are based on the Proposal of the experiment prepared to be published at IHEP. All experimental aspects including beam parameters evaluation, simulation and some test beam measurements of the major detectors, sensitivity and background estimations will be presented

Speaker: Prof. Vladimir Bolotov (Institute for Nuclear Research of RAS)

Slides Bolotov.ppt

1:00 PM Lunch

Summary and Final Remarks

73 Conference Summary

Speaker: Dr Gino Isidori (INFN-LNF, Frascati)

Slides Kaon2007_summary.pdf