P. McBride

We have compared the decay rates of KL and KS to π+π− and π0π0 final states using a subset of the data from the KTeV experiment (E832) at Fermilab. We find that the direct-CP-violation parameter Re(ε′/ε) is equal to [28.0±3.0(stat)±2.8(syst)]×10−4. This result definitively establishes the existence of CP violation in a decay process.Received 27 May 1999DOI:https://doi.org/10.1103/PhysRevLett.83.22©1999 American Physical Society

The reaction ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$ has been analyzed using 97 ${\mathrm{pb}}^{\ensuremath{-}1}$ of data taken with the Crystal Ball detector at the DESY ${e}^{\ensuremath{-}}{e}^{+}$ storage ring DORIS II at beam energies around 5.3 GeV. For the first time we have measured the cross section for $\ensuremath{\gamma}\ensuremath{\gamma}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$ for ${\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$ mvariant masses ranging from threshold to about 2 GeV. We measure an approximately flat cross section of about 10 nb for $W={m}_{{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}}<0.8$ GeV, which is below 0.6 GeV, in good agreement with a theoretical prediction based on an unitarized Born-term model. At higher invariant masses we observe formation of the ${f}_{2}(1270)$ resonance and a hint of the ${f}_{0}(975)$. We deduce the following two-photon widths: ${\ensuremath{\Gamma}}_{\ensuremath{\gamma}\ensuremath{\gamma}}({f}_{2}(1270))=3.19\ifmmode\pm\else\textpm\fi{}{0.16\ifmmode\pm\else\textpm\fi{}}_{0.28}^{0.29}$ keV and ${\ensuremath{\Gamma}}_{\ensuremath{\gamma}\ensuremath{\gamma}}({f}_{0}(975))<0.53$ keV at 90% C.L. The decay-angular distributions show the ${\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$ system to be dominantly spin 0 for $W<0.7$ GeV and spin 2, helicity 2 in the ${f}_{2}(1270)$ region, with helicity 0 contributing at most 22% (90% C.L.).

We present a series of measurements based on ${K}_{L,S}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ and ${K}_{L,S}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$ decays collected in 1996--1997 by the $\mathrm{KTeV}$ experiment (E832) at Fermilab. We compare these four $\stackrel{\ensuremath{\rightarrow}}{K}\ensuremath{\pi}\ensuremath{\pi}$ decay rates to measure the direct $\mathrm{CP}$ violation parameter $\mathrm{Re}({\ensuremath{\epsilon}}^{\ensuremath{'}}/\ensuremath{\epsilon})=(20.7\ifmmode\pm\else\textpm\fi{}2.8)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}.$ We also test $\mathrm{CPT}$ symmetry by measuring the relative phase between the $\mathrm{CP}$ violating and $\mathrm{CP}$ conserving decay amplitudes for $\stackrel{\ensuremath{\rightarrow}}{K}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ $({\ensuremath{\varphi}}_{+\ensuremath{-}})$ and for $\stackrel{\ensuremath{\rightarrow}}{K}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$ $({\ensuremath{\varphi}}_{00}).$ We find the difference between the relative phases to be $\ensuremath{\Delta}\ensuremath{\varphi}\ensuremath{\equiv}{\ensuremath{\varphi}}_{00}\ensuremath{-}{\ensuremath{\varphi}}_{+\ensuremath{-}}=(+0.39\ifmmode\pm\else\textpm\fi{}0.50)\ifmmode^\circ\else\textdegree\fi{},$ and the deviation of ${\ensuremath{\varphi}}_{+\ensuremath{-}}$ from the superweak phase to be ${\ensuremath{\varphi}}_{+\ensuremath{-}}\ensuremath{-}{\ensuremath{\varphi}}_{\mathrm{SW}}=(+0.61\ifmmode\pm\else\textpm\fi{}1.19)\ifmmode^\circ\else\textdegree\fi{};$ both results are consistent with $\mathrm{CPT}$ symmetry. In addition, we present new measurements of the ${K}_{L}$-${K}_{S}$ mass difference and ${K}_{S}$ lifetime: $\ensuremath{\Delta}m=(5261\ifmmode\pm\else\textpm\fi{}15)\ifmmode\times\else\texttimes\fi{}{10}^{6}\ensuremath{\Elzxh}{\mathrm{s}}^{\ensuremath{-}1}$ and ${\ensuremath{\tau}}_{S}=(89.65\ifmmode\pm\else\textpm\fi{}0.07)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12}\mathrm{s}.$

We present precise tests of CP and CPT symmetry based on the full dataset of K to pipi decays collected by the KTeV experiment at Fermi National Accelerator Laboratory during 1996, 1997, and 1999. This dataset contains 16 million K to 2pi0 and 69 million K to pi+pi- decays. We measure the direct CP violation parameter Re(epsilon'/epsilon) = (19.2 pm 2.1)x10-4. We find the KL-KS mass difference Deltam = (5270 pm 12)x10^6 hbar/s and the KS lifetime tauS = (89.62 pm 0.05)x10-12 s. We also measure several parameters that test CPT invariance. We find the difference between the phase of the indirect CP violation parameter, epsilon, and the superweak phase, phi_epsilon - phi_SW = (0.40 pm 0.56) degrees. We measure the difference of the relative phases between the CP violating and CP conserving decay amplitudes for K to pi+pi- (phi+-) and for K to 2pi0 (phi00), Delta phi = (0.30 pm 0.35) degrees. From these phase measurements, we place a limit on the mass difference between K0 and K0bar, DeltaM < 4.8 x 10-19 GeV/c^2 at 95% C.L. These results are consistent with those of other experiments, our own earlier measurements, and CPT symmetry.

We report on a search for the decay K(L)-->pi(0)&mgr;(+)&mgr;(-) carried out as a part of the KTeV experiment at Fermilab. This decay is expected to have a significant CP violating contribution and a direct measurement will either support the Cabibbo-Kobayashi-Maskawa mechanism for CP violation or point to new physics. Two events were observed in the 1997 data with an expected background of 0.87+/-0.15 events, and we set an upper limit B(K(L)-->pi(0)&mgr;(+)&mgr;(-))<3. 8x10(-10) at the 90% confidence level.

The KTeV/E799 experiment at Fermilab has searched for the rare kaon decay KL → π 0 e + e -.This mode is expected to have a significant CP violating component.The measurement of its branching ratio could support the Standard Model or could indicate the existence of new physics.This Letter reports new results from the 1999-2000 data set.One event is observed with an expected background at 0.99 ± 0.35 events.We set a limit on the branching ratio of 3.5 ×10 -10 at the 90% confidence level.Combining with the previous result based on the dataset taken in 1997 yields the final KTeV result: BR(KL → π 0 e + e -) < 2.8 ×10 -10 at 90% C.L.

The branching ratio of the rare decay π0→e+e− has been measured precisely, using the complete data set from the KTeV E799-II experiment at Fermilab. We observe 794 candidate π0→e+e− events using KL→3π0 as a source of tagged π0s. The expected background is 52.7±11.2 events, predominantly from high e+e− mass π0→e+e−γ decays. We have measured B(π0→e+e−,(me+e−/mπ0)2>0.95)=(6.44±0.25stat±0.22syst)×10−8, which is above the unitary bound from π0→γγ and within the range of theoretical expectations from the standard model.Received 24 October 2006DOI:https://doi.org/10.1103/PhysRevD.75.012004©2007 American Physical Society

The Fermilab KTeV experiment has searched for lepton-flavor-violating decays of the KL meson in three decay modes. We observe no events in the signal region for any of the modes studied, and we set the following upper limits for their branching ratios at the 90% C.L.: BR(KL→π0μ±e∓)<7.6×10−11; BR(KL→π0π0μ±e∓)<1.7×10−10; BR(π0→μ±e∓)<3.6×10−10. This result represents a factor of 82 improvement in the branching ratio limit for KL→π0μ±e∓ and is the first reported limit for KL→π0π0μ±e∓.Received 21 November 2007DOI:https://doi.org/10.1103/PhysRevLett.100.131803©2008 American Physical Society

We report the first observation of a manifestly CP violating effect in the K(L)-->pi(+)pi(-)e(+)e(-) decay mode. A large asymmetry was observed in the distribution of these decays in the CP-odd and T-odd angle straight phi between the decay planes of the e(+)e(-) and pi(+)pi(-) pairs in the K(L) center of mass system. After acceptance corrections, the overall asymmetry is found to be [13.6+/-2. 5(stat)+/-1.2(syst)]%. This is the largest CP-violating effect yet observed when integrating over the entire phase space of a mode and the first such effect observed in an angular variable.

We present new measurements of ${K}_{L}$ semileptonic form factors using data collected in 1997 by the KTeV (E832) experiment at Fermilab. The measurements are based on $1.9\ifmmode\times\else\texttimes\fi{}{10}^{6}$ ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}{e}^{\ensuremath{\mp}}\ensuremath{\nu}$ and $1.5\ifmmode\times\else\texttimes\fi{}{10}^{6}$ ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\mu}}^{\ensuremath{\mp}}\ensuremath{\nu}$ decays. For ${f}_{+}(t)$, we measure both a linear and quadratic term: ${\ensuremath{\lambda}}_{+}^{\ensuremath{'}}=(20.64\ifmmode\pm\else\textpm\fi{}1.75)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ and ${\ensuremath{\lambda}}_{+}^{\ensuremath{'}\ensuremath{'}}=(3.20\ifmmode\pm\else\textpm\fi{}0.69)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$. For ${f}_{0}(t)$, we find ${\ensuremath{\lambda}}_{0}=(13.72\ifmmode\pm\else\textpm\fi{}1.31)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$. These form factors are consistent with ${K}^{\ifmmode\pm\else\textpm\fi{}}$ form factors, suggesting that isospin symmetry breaking effects are small. We use our measured values of the form factors to evaluate the decay phase space integrals, ${I}_{K}^{e}=0.15350\ifmmode\pm\else\textpm\fi{}0.00105$ and ${I}_{K}^{\ensuremath{\mu}}=0.10165\ifmmode\pm\else\textpm\fi{}0.00080$, where errors include uncertainties arising from the form factor parametrizations.

We present a determination of the Cabibbo-Kobayashi-Maskawa parameter |V(us)| based on new measurements of the six largest K(L) branching fractions and semileptonic form factors by the KTeV (E832) experiment at Fermilab. We find |V(us)|=0.2252+/-0.0008(KTeV)+/-0.0021(ext), where the errors are from KTeV measurements and from external sources. We also use the measured branching fractions to determine the CP violation parameter |eta(+-)|=(2.228+/-0.005(KTeV)+/-0.009(ext))x10(-3).

The reaction \ensuremath{\gamma}\ensuremath{\gamma}\ensuremath{\rightarrow}${\ensuremath{\pi}}^{0}$\ensuremath{\eta} has been investigated with the Crystal Ball detector at the DESY storage ring DORIS II. Formation of \ensuremath{\delta}(980) and ${A}_{2}$(1320) has been observed with \ensuremath{\gamma}\ensuremath{\gamma} partial widths ${\ensuremath{\Gamma}}_{\ensuremath{\gamma}\ensuremath{\gamma}}$(${A}_{2}$)=1.14\ifmmode\pm\else\textpm\fi{}0.20\ifmmode\pm\else\textpm\fi{}0.2 6 keV and ${\ensuremath{\Gamma}}_{\ensuremath{\gamma}\ensuremath{\gamma}}$(\ensuremath{\delta})B(\ensuremath{\delta}\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\eta})=0.19\ifmmode\pm\else\textpm\fi{}0.07 $_{\mathrm{\ensuremath{-}}0.07}^{+0.10}$ keV.

We report on a new measurement of the branching ratio B(KL → π 0 γγ) using the KTeV detector.We reconstruct 1982 events with an estimated background of 608, that results in B(KL → π 0 γγ) = (1.29 ± 0.03stat ± 0.05syst) × 10 -6 .We also measure the parameter, aV , which characterizes the strength of vector meson exchange terms in this decay.We find aV = -0.31± 0.05stat ± 0.07syst.These results utilize the full KTeV data set collected from 1997 to 2000 and supersede earlier KTeV measurements of the branching ratio and aV .

We present new measurements of the six largest branching fractions of the ${K}_{L}$ using data collected in 1997 by the KTeV experiment (E832) at Fermilab. The results are $B({K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}{\mathrm{e}}^{\ensuremath{\mp}}\ensuremath{\nu})=0.4067\ifmmode\pm\else\textpm\fi{}0.0011$, $B({K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\mu}}^{\ensuremath{\mp}}\ensuremath{\nu})=0.2701\ifmmode\pm\else\textpm\fi{}0.0009$, $B({K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0})=0.1252\ifmmode\pm\else\textpm\fi{}0.0007$, $B({K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0})=0.1945\ifmmode\pm\else\textpm\fi{}0.0018$, $B({K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}})=(1.975\ifmmode\pm\else\textpm\fi{}0.012)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$, and $B({K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0})=(0.865\ifmmode\pm\else\textpm\fi{}0.010)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$, where statistical and systematic errors have been summed in quadrature. We also determine the $CP$ violation parameter $|{\ensuremath{\eta}}_{+\ensuremath{-}}|$ to be $(2.228\ifmmode\pm\else\textpm\fi{}0.010)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$. Several of these results are not in good agreement with averages of previous measurements.

We present a measurement of the charge asymmetry delta(L) in the mode K(L)-->pi(+/-)e(-/+)nu based on 298 x 10(6) analyzed decays. We measure a value of delta(L) = [3322+/-58(stat)+/-47(syst)]x10(-6), in good agreement with previous measurements and 2.4 times more precise than the current best published result. The result is used to place more stringent limits on CPT and DeltaS = DeltaQ violation in the neutral kaon system.

The design and operation of precision drift chambers with multisampling as well as the concepts and methods for reaching an extraordinary degree of precision in mechanics and calibration are described. Specific instruments were developed for this purpose. The concept of reproducible positioning and the implementation to 30 μm accuracy, showing stability over three years, is given. Calibration and analysis with UV-laser and cosmic test measurements are outlined with the critical results. The experience of calibration and reliability of the large system in an actual L3 running experiment is analyzed. The resolution under “battle conditions” at LEP resulted in Δpp = (2.50±0.04)% at 45.6 GeV and will be presented in detail. The concept is well suited for future TeV energies.

The Crystal Ball detector has been used at the DORIS II storage ring at DESY to study the reaction ${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\gamma}*\ensuremath{\gamma}*\ensuremath{\rightarrow}${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\gamma}\ensuremath{\gamma}, where X is a narrow resonance with mass between 100 and 3000 MeV. Formation of ${\ensuremath{\pi}}^{0}$, \ensuremath{\eta}, and \ensuremath{\eta}' mesons is observed, and the following meson partial widths are obtained: ${\mathrm{\ensuremath{\Gamma}}}_{\mathrm{\ensuremath{\pi}}0\mathrm{\ensuremath{\Gamma}}0\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}}$=7.7\ifmmode\pm\else\textpm\fi{}0.5\ifmmode\pm\else\textpm\fi{}0.5 eV, ${\mathrm{\ensuremath{\Gamma}}}_{\mathrm{\ensuremath{\eta}}\mathrm{\ensuremath{-}}\ensuremath{\gamma}\ensuremath{\gamma}}$=0.514\ifmmode\pm\else\textpm\fi{}0.017\ifmmode\pm\else\textpm\fi{}0.035 keV, and ${\mathrm{\ensuremath{\Gamma}}}_{\mathrm{\ensuremath{\eta}}\mathcal{'}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}}$=4.7\ifmmode\pm\else\textpm\fi{}0.5\ifmmode\pm\else\textpm\fi{}0.5 keV. No other narrow resonances are observed, and upper limits are given for the product ${\ensuremath{\Gamma}}_{X\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}}$${B}_{X\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}}$. .AE

We present a series of measurements based on K -> pi+pi- and K -> pi0pi0 decays collected in 1996-1997 by the KTeV experiment (E832) at Fermilab. We compare these four K -> pipi decay rates to measure the direct CP violation parameter Re(e'/e) = (20.7 +- 2.8) x 10^-4. We also test CPT symmetry by measuring the relative phase between the CP violating and CP conserving decay amplitudes for K->pi+pi- (phi+-) and for K -> pi0pi0 (phi00). We find the difference between the relative phases to be Delta-phi = phi00 - phi+- = (+0.39 +- 0.50) degrees and the deviation of phi+- from the superweak phase to be phi+- - phi_SW =(+0.61 +- 1.19) degrees; both results are consistent with CPT symmetry. In addition, we present new measurements of the KL-KS mass difference and KS lifetime: Delta-m = (5261 +- 15) x 10^6 hbar/s and tauS = (89.65 +- 0.07) x 10^-12 s.

This document describes the simulation framework used in the Snowmass Energy Frontier studies for future Hadron Colliders. An overview of event generation with Madgraph5 along with parton shower and hadronization with Pythia6 is followed by a detailed description of pile-up and detector simulation with Delphes3. Details of event generation are included in a companion paper cited within this paper. The input parametrization is chosen to reflect the best object performance expected from the future ATLAS and CMS experiments; this is referred to as the "Combined Snowmass Detector". We perform simulations of pp interactions at center-of-mass energies √s = 14, 33, and 100 TeV with 0, 50, and 140 additional pp pile-up interactions. The object performance with multi-TeV pp collisions are studied for the first time using large pile-up interactions.

We report on a search for the decay KL→π0ν¯ν, carried out as a part of E799-II, a rare KL decay experiment at Fermilab. Within the standard model, the KL→π0ν¯ν decay is dominated by direct CP violating processes, and thus an observation of the decay implies confirmation of direct CP violation. No events were observed, and we set an upper limit for the branching ratio of KL→π0ν¯ν to be <5.9×10−7 at the 90% confidence level.Received 8 July 1999DOI:https://doi.org/10.1103/PhysRevD.61.072006©2000 American Physical Society

We present a new determination of the parity of the neutral pion via the double Dalitz decay pi0-->e+e-e+e-. Our sample, which consists of 30,511 candidate decays, was collected from KL-->pi0pi0pi0 decays in flight at the KTeV-E799 experiment at Fermi National Accelerator Laboratory. We confirm the negative pi0 parity and place a limit on scalar contributions to the pi0-->e+e-e+e- decay amplitude of less than 3.3% assuming CPT conservation. The pi0gamma*gamma* form factor is well described by a momentum-dependent model with a slope parameter fit to the final state phase-space distribution. Additionally, we have measured the branching ratio of this mode to be B(pi0-->e+e-e+e-)=(3.26+/-0.18)x10(-5).

We report on a new measurement of the decay ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}\ensuremath{\gamma}\ensuremath{\gamma}$ by the KTeV experiment at Fermilab. We determine the ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}\ensuremath{\gamma}\ensuremath{\gamma}$ branching ratio to be $(1.68\ifmmode\pm\else\textpm\fi{}0.07\ifmmode\pm\else\textpm\fi{}0.08)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$. Our data show the first evidence for a low-mass $\ensuremath{\gamma}\ensuremath{\gamma}$ signal as predicted by recent $O({p}^{6})$ chiral perturbation calculations which include vector meson exchange contributions. From our data, we extract a value for the effective vector coupling ${a}_{V}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}0.72\ifmmode\pm\else\textpm\fi{}0.05\ifmmode\pm\else\textpm\fi{}0.06$.

Snowmass is a US long-term planning study for the high-energy community by the American Physical Society's Division of Particles and Fields. For its simulation studies, opportunistic resources are harnessed using the Open Science Grid infrastructure. Late binding grid technology, GlideinWMS, was used for distributed scheduling of the simulation jobs across many sites mainly in the US. The pilot infrastructure also uses the Parrot mechanism to dynamically access CvmFS in order to ascertain a homogeneous environment across the nodes. This report presents the resource usage and the storage model used for simulating large statistics Standard Model backgrounds needed for Snowmass Energy Frontier studies.

We present the first measurement of the form factor ratios g(1)/f(1) (direct axial vector to vector), g(2)/f(1) (second class current), and f(2)/f(1) (weak magnetism) for the decay Xi(0)-->Sigma(+)e(-)nu macro(e) using the KTeV (E799) beam line and detector at Fermilab. From the Sigma(+) polarization measured with the decay Sigma(+)-->p pi(0) and the e(-)-nu; correlation, we measure g(1)/f(1) to be 1.32+/-(0.21)(0.17)(stat)+/-0.05(syst), assuming the SU(3)(f) (flavor) values for g(2)/f(1) and f(2)/f(1). Our results are all consistent with exact SU(3)(f) symmetry.

We present results of a search for a new form of hadronic matter, a six-quark, dibaryon state called the H0, a state predicted to exist in several theoretical models. Analyzing data collected by experiment E799-II at Fermilab, we searched for the decay H0-->Lambdappi(-) and found no candidate events. We place an upper limit on [B(H0-->Lambdappi(-))dsigma(H)/dOmega]/(dsigma(Xi)/dOmega) and, in the context of published models, exclude the region of lightly bound mass states just below the LambdaLambda mass threshold, 2.194<M(H)<2.231 GeV/c(2), with lifetimes from approximately 5x10(-10) sec to approximately 1x10(-3) sec.

We have searched for axion and light Higgs boson production in the channel ϒ (1S) → (a0 or h0) + γ, where the non-interacting axion a0 and the Higgs boson h0 do not decay in the detector. We find no evidence for an axion and give an upper limit, Br(ϒ (1S) → a0γ) < 4.0 × 10−5 (90% CL), for long-lived axions. Combining our limit with the previous search in J/ψ decays, we are able to rule out the axion in the standard model with first order QCD corrections. Our ϒ (1S) data also rule out a Higgs boson with mass mh < 86 MeV.

Using a sample of 68.3×106 KL→π0π0π0 decays collected in 1996–1999 by the KTeV (E832) experiment at Fermilab, we present a detailed study of the KL→π0π0π0 Dalitz plot density. We report the first observation of interference from KL→π+π−π0 decays in which π+π− rescatters to π0π0 in a final-state interaction. This rescattering effect is described by the Cabibbo-Isidori model, and it depends on the difference in pion scattering lengths between the isospin I=0 and I=2 states, a0−a2. Using the Cabibbo-Isidori model, and fixing (a0−a2)mπ+=0.268±0.017 as measured by the CERN-NA48 collaboration, we present the first measurement of the KL→π0π0π0 quadratic slope parameter that accounts for the rescattering effect: h000=(+0.59±0.20stat±0.48syst±1.06ext)×10−3, where the uncertainties are from data statistics, KTeV systematic errors, and external systematic errors. Fitting for both h000 and a0−a2, we find h000=(−2.09±0.62stat±0.72syst±0.28ext)×10−3, and mπ+(a0−a2)=0.215±0.014stat±0.025syst±0.006ext; our value for a0−a2 is consistent with that from NA48.1 MoreReceived 24 June 2008DOI:https://doi.org/10.1103/PhysRevD.78.032009©2008 American Physical Society

We report on a search for the decay KL-->pi(0)e+e- carried out by the KTeV/E799 experiment at Fermilab. This decay is expected to have a significant CP violating contribution and the measurement of its branching ratio could support the Cabibbo-Kobayashi-Maskawa mechanism for CP violation or could point to new physics. Two events were observed in the 1997 data with an expected background of 1.06+/-0.41 events, and we set an upper limit B(KL-->pi(0)e+e-)<5.1 x 10(-10) at the 90% confidence level.

The reaction ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$\ensuremath{\eta}${\ensuremath{\pi}}^{0}$${\ensuremath{\pi}}^{0}$ has been observed with the Crystal Ball detector at the DORIS II storage ring at DESY. The \ensuremath{\eta}${\ensuremath{\pi}}^{0}$${\ensuremath{\pi}}^{0}$ mass spectrum is dominated by the \ensuremath{\eta}', and the two-photon width ${\ensuremath{\Gamma}}_{\ensuremath{\eta}\mathcal{'}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}}$ is determined to be 4.6\ifmmode\pm\else\textpm\fi{}0.4\ifmmode\pm\else\textpm\fi{}0.6 keV. Limits on ${\ensuremath{\Gamma}}_{X\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}}$\ifmmode\times\else\texttimes\fi{}${B}_{X\ensuremath{\rightarrow}\ensuremath{\eta}\ensuremath{\pi}\ensuremath{\pi}}$ are given for other possible states.

Short-lived particles produced in association with muons have been observed in the interactions of 350-GeV/c protons with neon in a high-resolution streamer chamber. The characteristics of these events are consistent with the expected properties of charmed particles if the average lifetime lies between ${10}^{\ensuremath{-}13}$ and 2\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}12}$ sec. With the assumption that the observed events are mainly ${D}^{\ifmmode\pm\else\textpm\fi{}}$ mesons with lifetimes of approximately ${10}^{\ensuremath{-}12}$ sec, the production cross section is estimated to lie between 20 and 50 \ensuremath{\mu}b per nucleon.

Using the published KTeV samples of K_L --> pi^{\pm} e^{\mp} nu and K_L --> pi^{\pm} mu^{\mp} nu decays [1], we perform a reanalysis of the scalar and vector form factors based on the dispersive parameterization [2,3]. We obtain phase space integrals I^e_K = 0.15446 \pm 0.00025 and I^{mu}_K = 0.10219 \pm 0.00025. For the scalar form factor parameterization, the only free parameter is the normalized form factor value at the Callan-Treiman point (C); our best fit results in ln C = 0.1915 \pm 0.0122. We also study the sensitivity of C to different parametrizations of the vector form factor. The results for the phase space integrals and C are then used to make tests of the Standard Model. Finally, we compare our results with lattice QCD calculations of F_K/F_pi and f_+(0).

Free convection in a vertical cylinder of water is studied in the vicinity of the density maximum at 4 °C. Results are presented both from cooling curve measurements (using a series of thermistors along the central axis of the cylinder) and from flow visualization experiments (using particle image velocimetry), and a comparison is made with simulations. The reversal of the overall flow direction as the temperature crosses the maximum density region gives rise to a plateau feature in the cooling curve, which may be explained by the formation of a rising toroidal structure along the column boundary. This feature effectively diverts flow away from the inner region of the cylinder, resulting in a temporary cessation of convective cooling within this region.

Using the complete KTeV data set of 5241 candidate ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{e}^{+}{e}^{\ensuremath{-}}$ decays (including an estimated background of $204\ifmmode\pm\else\textpm\fi{}14$ events), we have measured the coupling ${g}_{\mathrm{CR}}=0.163\ifmmode\pm\else\textpm\fi{}0.014(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.023(\mathrm{syst})$ of the $CP$ conserving charge radius process and from it determined a ${K}^{0}$ charge radius of $⟨{r}_{{K}^{0}}^{2}⟩=[\ensuremath{-}0.077\ifmmode\pm\else\textpm\fi{}0.007(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.011(\mathrm{syst})]f{m}^{2}$. We have determined a first experimental upper limit of 0.04 (90% C.L.) for the ratio $\frac{|{g}_{E1}|}{|{g}_{M1}|}$ of the couplings for the $E1$ and $M1$ direct photon emission processes. We also report the measurement of $|{g}_{M1}|$ including a vector form factor $|{\stackrel{\texttildelow{}}{g}}_{M1}|(1+\frac{{a}_{1}/{a}_{2}}{({M}_{\ensuremath{\rho}}^{2}\ensuremath{-}{M}_{K}^{2})+2{M}_{K}{E}_{{\ensuremath{\gamma}}^{*}}})$, where $|{\stackrel{\texttildelow{}}{g}}_{M1}|=1.11\ifmmode\pm\else\textpm\fi{}0.12(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.08(\mathrm{syst})$ and ${a}_{1}/{a}_{2}=[\ensuremath{-}0.744\ifmmode\pm\else\textpm\fi{}0.027(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.032(\mathrm{syst})]\text{ }\text{ }\mathrm{Ge}{\mathrm{V}}^{2}/{c}^{2}$. Finally, a $CP$-violating asymmetry of $[13.6\ifmmode\pm\else\textpm\fi{}1.4(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}1.5(\mathrm{syst})]%$ in the $CP$ and $T$ odd angle $\ensuremath{\phi}$ between the decay planes of the ${e}^{+}{e}^{\ensuremath{-}}$ and ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ pairs in the ${K}_{L}$ center of mass is reported.

The CMS experiment expects to manage several Pbytes of data each year during the LHC programme, distributing them over many computing sites around the world and enabling data access at those centers for analysis. CMS has identified the distributed sites as the primary location for physics analysis to support a wide community with thousands potential users. This represents an unprecedented experimental challenge in terms of the scale of distributed computing resources and number of user. An overview of the computing architecture, the software tools and the distributed infrastructure is reported. Summaries of the experience in establishing efficient and scalable operations to get prepared for CMS distributed analysis are presented, followed by the user experience in their current analysis activities.

We report on two null searches, one for the spontaneous appearance of ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ pairs, another for a single ${\ensuremath{\pi}}^{0}$, consistent with the decay of a long-lived neutral particle into hadrons and an unseen neutral particle. For the lowest level gluon-gluino bound state, known as the ${R}^{0}$, we exclude the decays ${R}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{\ensuremath{\gamma}}$ and ${R}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{\ensuremath{\gamma}}$ for the masses of ${R}^{0}$ and $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{\ensuremath{\gamma}}$ in the theoretically allowed range. In the most interesting ${R}^{0}$ mass range, $\ensuremath{\le}3\mathrm{GeV}/{c}^{2}$, we exclude ${R}^{0}$ lifetimes from $3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}\mathrm{sec}$ to as high as ${10}^{\ensuremath{-}3}\mathrm{sec}$, assuming perturbative QCD production for the ${R}^{0}$.

The KTeV experiment at Fermilab has isolated a total of 132 events from the rare decay K(L)-->e+ e- mu+ mu-, with an estimated background of 0.8 events. The branching ratio of this mode is determined to be [2.69+/-0.24(stat)+/-0.12(syst)]x10(-9), with a radiative cutoff of M(2)(ee mu mu)/M(2)(K)>0.95. The first measurement using this mode of the parameter alpha from the D'Ambrosio-Isidori-Portolès (DIP) model of the K(L)gamma*gamma* vertex yields a result of -1.59+/-0.37, consistent with values obtained from other decay modes. Because of the limited statistics, no sensitivity is found to the DIP parameter beta. We use this decay mode to set limits on CP and lepton violation.

We study infrared QCD effects in radiative quarkonia decays. We examine the endpoint region z→1 of the photon spectrum. We point out a cancellation mechanism for the corrections in αsnlnm(1−z), m⩽2n, in the short-distance coefficient for the color-singlet Fock state in the quarkonium. The cancellation is due to the coherence of the color radiation, and applies even though logarithmic contributions are present in the jet distributions associated with the decay. We comment on the implications of our results for the modeling of hadronization in the endpoint region and for the role of color-octet states in the quarkonium.

We observe 441 K(L)-->e(+)e(-)e(+)e(-) candidate events with a background of 4.2 events and measure B(K(L)-->e(+)e(-)e(+)e(-)) = [3.72+/-0.18(stat)+/-0.23(syst)]x10(-8) in the KTeV/E799II experiment at Fermilab. Using the distribution of the angle between the planes of the e(+)e(-) pairs, we measure the CP parameters beta(CP) = -0.23+/-0.09(stat)+/-0.02(syst) and gamma(CP) = -0.09+/-0.09(stat)+/-0.02(syst). We also present the first detailed study of the e(+)e(-) invariant mass spectrum in this decay mode.

We have performed studies of the K(0)(L)-->pi(+)pi(-)gamma direct emission ( DE) and inner Bremsstrahlung ( IB) vertices, based on data collected by KTeV during the 1996 Fermilab fixed target run. We find a(1)/a(2) = -0.737+/-0.034 GeV2 for the DE form-factor parameter in the rho-propagator parametrization, and report on fits of the form factor to linear and quadratic functions as well. We concurrently measure gamma(K(0)(L)-->pi(+)pi(-)gamma,E(*)(gamma)>20 MeV)/gamma(K(0)(L)-->pi(+)pi(-)) = (20.8+/-0.3)x10(-3), and a K(0)(L)-->pi(+)pi(-)gamma DE/(DE+IB) branching ratio of 0.683+/-0.011.

The recent discovery of a large CP violating asymmetry in KL-->pi+pi-e+e- mode has prompted us to seach for the associated KL-->pi 0 pi 0 e+e- decay mode in the KTeV-E799 experiment at Fermilab. In 2.7 x 10(11) K(L) decays, one candidate event has been observed with an expected background of 0.3 event, resulting in an upper limit for the KL-->pi 0 pi 0 e+e- branching ratio of 6.6 x 10(-9) at the 90% C.L.

We present measurements of ${\mathcal{R}}_{\mathrm{K}\ensuremath{\ell}3\ensuremath{\gamma}}\ensuremath{\equiv}\ensuremath{\Gamma}({\mathrm{K}}_{\mathrm{L}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\ell}}^{\ensuremath{\mp}}\ensuremath{\nu}\ensuremath{\gamma};{\mathrm{E}}_{\ensuremath{\gamma}}^{\ensuremath{\star}}&gt;10\text{ }\text{ }\mathrm{M}\mathrm{e}\mathrm{V})/\ensuremath{\Gamma}({\mathrm{K}}_{\mathrm{L}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\ell}}^{\ensuremath{\mp}}\ensuremath{\nu})$, where $\ensuremath{\ell}=\ensuremath{\mu}$ or $e$, and ${\mathrm{E}}_{\ensuremath{\gamma}}^{\ensuremath{\star}}$ is the photon energy in the kaon rest frame. These measurements are based on ${K}_{L}$ decays collected in 1997 by the KTeV (E832) experiment at Fermilab. With samples of 1385 ${\mathrm{K}}_{\mathrm{L}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\mu}}^{\ensuremath{\mp}}\ensuremath{\nu}\ensuremath{\gamma}$ and 14221 ${\mathrm{K}}_{\mathrm{L}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}{\mathrm{e}}^{\ensuremath{\mp}}\ensuremath{\nu}\ensuremath{\gamma}$ candidates, we find ${\mathcal{R}}_{\mathrm{K}\ensuremath{\mu}3\ensuremath{\gamma}}=(0.530\ifmmode\pm\else\textpm\fi{}0.019)%$ and ${\mathcal{R}}_{\mathrm{K}\mathrm{e}3\ensuremath{\gamma}}=(4.942\ifmmode\pm\else\textpm\fi{}0.062)%$. We also examine distributions of photon energy and lepton-photon angle.

The xi0 muon semileptonic decay has been observed for the first time with nine identified events using the KTeV beam line and detector at Fermilab. The decay is normalized to the xi0 beta decay mode and yields a value for the ratio of decay rates gamma(xi0 --> sigma+ mu- nu(mu))/gamma(xi0 --> sigma+ e- nu(e)) of [1.8(-0.5)(+0.7)(stat) +/- 0.2(syst)] x 10(-2). This is in agreement with the SU(3) flavor symmetric quark model.

The KTeV E799 experiment has conducted a search for the rare decays KL->pi0pi0mu+mu- and KL->pi0pi0X0->pi0pi0mu+mu-, where the X0 is a possible new neutral boson that was reported by the HyperCP experiment with a mass of (214.3 pm 0.5) MeV/c^{2}. We find no evidence for either decay. We obtain upper limits of Br(KL->pi0pi0X0->pi0pi0mu+mu-) < 1.0 x 10^{-10} and Br(KL->pi0pi0mu+mu-) < 9.2 x 10^{-11} at the 90% confidence level. This result rules out the pseudoscalar X0 as an explanation of the HyperCP result under the scenario that the \bar{d}sX0 coupling is completely real.

The Crystal Ball detector at the Doris II storage ring at DESY was used to search for the exotic decay processes τ→eγ,τ→eπ0, and τ→eη. No signal was observed. We obtained the following 90% CL upper limits on the branching fractions: B(τ→eγ)<2.0×10−4, B(τ→eπ0)<1.4×10−4, B(τ→eη)<2.4×10−4.

The branching ratio of the rare decay ${\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}$ has been measured in E799-II, a rare kaon decay experiment using the KTeV detector at Fermilab. We observed 275 candidate ${\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}$ events, with an expected background of $21.4\ifmmode\pm\else\textpm\fi{}6.2$ events which includes the contribution from Dalitz decays. We measured $B[{\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}},({m}_{{e}^{+}{e}^{\ensuremath{-}}}{/m}_{{\ensuremath{\pi}}^{0}}{)}^{2}&gt;0.95]\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}(6.09\ifmmode\pm\else\textpm\fi{}0.40\ifmmode\pm\else\textpm\fi{}0.24)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$, where the first error is statistical and the second systematic. This result is the first significant observation of the excess rate for this decay above the unitarity lower bound.

Using the Crystal Ball detector at the DORIS II e+e− storage ring, we measure the ηπ0π0 mass spectrum in the reaction e+e−→e+e−ηπ0π0→e+e−6γ from the ηπ0π0 threshold to about 2500 MeV/c2. The spectrum is dominated by the η′, for which we determine Γγγ(η′)BR(η'→6γ)=0.36±0.02±0.03 keV. In addition, we observe an enhancement in the cross section near 1900 MeV/c2 which we attribute to the two-photon production of a new resonance X(1900). The angular distributions and the invariant mass distribution of the ηπ0 subsystem are consistent with those expected for the hypothetical η2 meson with JPC=2−+. For this JP assignment the resonance parameters are M(X) = 1876 ±35±50 MeV/c2, Γtot(X)=228±90±34 MeV/c2 and Γγγ(X)BR(X→ηππ) = 0.9±0.2±0.3 keV.

We have studied the rare weak radiative hyperon decay Xi degrees -->Sigma degrees gamma in the KTeV experiment at Fermilab. We have identified 4045 signal events over a background of 804 events. The dominant Xi degrees -->Lambdapi degrees decay, which was used for normalization, is the only important background source. An analysis of the acceptance of both modes yields a branching ratio of B(Xi degrees -->Sigma degrees gamma)/B(Xi degrees -->Lambdapi degrees ) = (3.34+/-0.05+/-0.09)x10(-3). By analyzing the final state decay distributions, we have also determined that the Sigma degrees emission asymmetry parameter for this decay is alpha(XiSigma) = -0.63+/-0.09.

We present a new measurement of the branching ratio of the decay K_L -> pi e nu gamma (Ke3g) with respect to K_L -> pi e nu (Ke3), and the first study of the photon energy spectrum in this decay. We find BR(Ke3g, E*g>30 MeV, theta*_eg>20 deg)/BR(Ke3) = 0.908 +- 0.008 (stat.) +0.013-0.012 (syst.). Our measurement of the spectrum is consistent with inner bremsstrahlung as the only source of photons in Ke3g.

Using the published KTeV sample of 2×106 KL→π±e∓ν decays [1] and a new form factor expansion with a rigorous bound on higher order terms [2], we present a new determination of the KL→π±e∓ν form factor and phase space integral. Compared to the previous KTeV result [1], the uncertainty in the new form factor expansion is negligible and results in an overall uncertainty in the phase space integral (IKe) that is a factor of 2 smaller: IKe=0.15392±0.00048.Received 27 August 2006DOI:https://doi.org/10.1103/PhysRevD.74.097101©2006 American Physical Society

We report on a study of the decay KL→e+e−γγ carried out as a part of the KTeV/E799 experiment at Fermilab. The 1997 data yielded a sample of 1543 events, including an expected background of 56±8 events. An effective form factor was determined from the observed distribution of the e+e− invariant mass. Using this form factor in the calculation of the detector acceptance, the branching ratio was measured to be B(KL→e+e−γγ,Eγ*>5MeV)=(5.84±0.15(stat)±0.32(syst))×10−7. Received 23 October 2000DOI:https://doi.org/10.1103/PhysRevD.64.012003©2001 American Physical Society

We report on a new measurement of the branching ratio B(KL → π 0 e + e -γ) using the KTeV detector.This analysis uses the full KTeV data set collected from 1997 to 2000.We reconstruct 139 events over a background of 14, which results in B(KL → π 0 e + e -γ) = (1.62 ± 0.14stat ± 0.09syst) × 10 -8 .This result supersedes the earlier KTeV measurement of this branching ratio.

The E799-II (KTeV) experiment at Fermilab has collected 83 262 KL→e+e−γ(γ) events above a background of 79 events. We measure a decay width, normalized to the KL→π0π0π0D (π0→γγ, π0→γγ, π0D→e+e−γ(γ)) decay width, of Γ(KL→e+e−γ(γ))/Γ(KL→π0π0π0D)=(1.3302±0.0046stat±0.0102syst)×10−3. We also measure parameters of two KLγ∗γ form factor models. In the Bergström-Massó-Singer parametrization, we find CαK∗=−0.517±0.030stat±0.022syst. We separately fit for the first parameter of the D’Ambrosio-Isidori-Portolés model and find αDIP=−1.729±0.043stat±0.028syst.Received 23 February 2007DOI:https://doi.org/10.1103/PhysRevLett.99.051804©2007 American Physical Society

A prototype of the L3 muon chamber module, designed for measuring muon track positions, was built and tested. Measured simulated tracks made by an UV laser beam used for the internal alignment of the chambers in the module appeared to display a systematic positional error. The module measures the slope of laser tracks with high precision. The induced charge mechanism of proportional chambers creates an error in the slope of the same track if measured using a single wire plane. A simulation of the wire signals resulted in a good description of the error; also the calculated decrease in the signal size for tracks parallel to the wire plane tallied with the measurements.

We use K(L)'s in the 100-200 GeV energy range to produce 147 candidate events of the axial vector pair K1(1270)-K1(1400) in the nuclear Coulomb field of a Pb target and determine the radiative widths Gamma(K1(1400)-->K0+gamma)=280.8+/-23.2(stat)+/-40.4(syst) keV and Gamma(K1(1270)-->K0+gamma)=73.2+/-6.1(stat)+/-28.3(syst) keV. These first measurements appear to be lower than the quark-model predictions. We also place upper limits on the radiative widths for K(*)(1410) and K(*)(2)(1430) and find that the latter is vanishingly small in accord with SU(3) invariance in the naive quark model.

We have observed the decay ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}\ensuremath{\gamma}\ensuremath{\gamma}$ at the KTeV experiment at Fermilab. This decay presents a formidable background to the search for new physics in ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}.$ The 1997 data yielded a sample of 4 signal events, with an expected background of $0.155\ifmmode\pm\else\textpm\fi{}0.081$ events. The branching ratio is $\mathcal{B} {(K}_{L}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}\ensuremath{\gamma}\ensuremath{\gamma})=[{10.4}_{\ensuremath{-}5.9}^{+7.5}\mathrm{}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.7\mathrm{}(\mathrm{syst})]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$ with ${m}_{\ensuremath{\gamma}\ensuremath{\gamma}}&gt;~1 \mathrm{MeV}{/c}^{2},$ consistent with a QED calculation which predicts $(9.1\ifmmode\pm\else\textpm\fi{}0.8)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}.$

The polarization of neutral Cascade and anti-Cascade hyperons produced by 800 GeV/c protons on a BeO target at a fixed targeting angle of 4.8 mrad is measured by the KTeV experiment at Fermilab. Our result of 9.7% for the neutral Cascade polarization shows no significant energy dependence when compared to a result obtained at 400 GeV/c production energy and at twice our targeting angle. The polarization of the neutral anti-Cascade is measured for the first time and found to be consistent with zero. We also examine the dependence of polarization on transverse production momentum.

The L3 detector is designed to measure the muon momentum with a 2% resolution at p = 45 GeV/c. We discuss here the systems we developed to reach the required accuracy and control the mechanical alignment at running time. We also report on the test done on the muon spectrometer with UV lasers and cosmic rays.

The L3 muon spectrometer is presented. Characteristics, useful for experiments at future accelerators, are highlighted. Particular emphasis is given to the systems envisaged to keep the error on the relative alignment of detectors below 30 μm and so reach a momentum resolution Δpp = 2% at p = 45 GeV/c.

We have collected a 43 event sample of the decay K(L)-->e(+)e(-)mu(+)mu(-) with negligible backgrounds and measured its branching ratio to be (2.62+/-0.40+/-0.17)x10(-9). We see no evidence for CP violation in this decay. In addition, we set the 90% confidence upper limit on the combined branching ratios for the lepton flavor violating decays K(L)-->e(+/-)e(+/-)mu(-/+)mu(-/+) at B(K(L)-->e(+/-)e(+/-)mu(-/+)mu(-/+))< or =1.23x10(-10), assuming a uniform phase space distribution.

This Letter is the first report of the KL→π±e∓νe+e− decay. Based on 19 208±144 events, we determine the branching fraction, B(KL→π±e∓νe+e−;Me+e−>5 MeV/c2,E∗e+e−>30 MeV)=(1.285±0.041)×10−5, and Γ(Ke3ee;Me+e−>5 MeV/c2)/Γ(Ke3)=[4.57±0.04(stat)±0.14(syst)]×10−5. This ratio agrees with a theoretical prediction based on chiral perturbation theory (ChPT) calculated to O(p4). The measured kinematical distributions agree with those predicted by just ChPT O(p4), but show significant disagreement with ones predicted by leading-order ChPT.Received 22 May 2007DOI:https://doi.org/10.1103/PhysRevLett.99.081803©2007 American Physical Society

The scale and performance parameters of the ILC require new thinking in regards to control system design. This design work has begun quite early in comparison to most accelerator projects, with the goal of uniquely high overall accelerator availability. Among the design challenges are high control system availability, precision timing and rf phase reference distribution, standardizing of interfaces, operability, and maintainability. We present the current state of the design and take a prospective look at ongoing research and development projects.

The Simulation Group at Fermilab has developed a fast simulation package for detector design studies. The goal of this package, called MCFast, is to provide a fast and flexible framework for the comparison of detector geometries and, in particular, to compare experiments designed to study the production and decay of B hadrons in a collider environment. The code is written primarily in Fortran and C and the fast tracking is based on the Kalman filter technique. A 3-D Graphics package has been developed to display the detector geometry, tracks and calorimeter hits. Recent updates to the MCFast package include improvements to the tracing, track fitting, calorimetry and graphics.

that would exploit the existing Accumulator and Debuncher rings to generate the required characteristics of the primary proton beam. The proposal requires only modest modifications to the accelerator complex after including those already planned for the NOvA experiment, with which this experiment would be fully compatible. The search for lepton flavor violation (LFV) has long played an important role in the evolution of our understanding of electroweak interactions. The neutrinoless conversion of a muon to an electron in the field of a nucleus is a particularly interesting example of an LFV process involving charged leptons. In the Standard Model, such conversions would take place via loop diagrams involving virtual neutrino mixing, at a rate far below the threshold of any currently conceivable experiment. Indeed, any detectable signal would be a definite indication, albeit indirect, of new dynamics at multi-TeV energy scales. Enhanced rate for this process is an almost universal feature of beyond the Standard Model physics, and the fact that such a process has not been observed has constrained or eliminated many models [1]. While it is widely believed that new physics will appear at LHC energies, the LHC is not well-equipped to study LFV directly. An often-quoted example is in the case of supersymmetry. The LHC will probe slepton masses, but it cannot compete with muon decay experiments in constraining the slepton mixing angles. Sensitive searches for rare or forbidden leptonic and semi-leptonic LFV processes, especially those involving charged leptons, are essential for the comprehensive characterization of new high energy physics. While there are several potential reactions that can be used to probe LFV, muon to electron conversion has the remarkable feature that it does not require the coincidence of two final-state particles. The spectacular signature is a single conversion electron of well-defined energy, separated from most of the sources of background. As a result, very high muon data rates can be handled and an unusually sensitive search for LFV becomes feasible. Indeed, at the level of sensitivity discussed below, a large class of supersymmetric models would predict 100's of conversion events. Additionally, compositeness and Z{prime} models would be probed at the multi-TeV scale in a manner complementary to direct LHC searches. Lepto-quarks would be probed at the 3000 TeV scale. Muon to electron conversion is therefore sensitive to many new physics scenarios at energy scales that cannot be probed by direct searches using other foreseeable accelerators.

Abstract Methods allowing the precise determination of momenta in the TeV region are demonstrated. Their application in future collider detectors will enable, by magnetic analysis, 1–2% mass resolution for 1 TeV dimuons.

The Crystal Ball detector at the Doris II storage ring at DESY has been used to study the electron energy spectrum of the decay τ→evv̄. In the standard model the Lorentz structure of the decay matrix element is of the well known V-A type, resulting in a Michel parameter of p=0.75. Our spectrum is found to be consistent with this value. A fit yields the value of 0.64±0.07.

We report on the first observation of the decay KL -> pi0 ee gamma by the KTeV E799 experiment at Fermilab. Based upon a sample of 48 events with an estimated background of 3.6 +/- 1.1 events, we measure the KL -> pi0 ee gamma branching ratio to be (2.34 +/- 0.35 +/- 0.13)x10^{-8}. Our data agree with recent O(p^6) calculations in chiral perturbation theory that include contributions from vector meson exchange through the parameter a_V. A fit was made to the KL -> pi0 ee gamma data for a_V with the result -0.67 +/- 0.21 +/- 0.12, which is consistent with previous results from KTeV.

The CMS experiment is about to embark on its first physics run at the LHC. To maximize the effectiveness of physicists and technical experts at CERN and worldwide and to facilitate their communications, CMS has established several dedicated and inter-connected operations and monitoring centres. These include a traditional 'Control Room' at the CMS site in France, a 'CMS Centre' for up to fifty people on the CERN main site in Switzerland, and remote operations centres, such as the 'LHC@FNAL' centre at Fermilab. We describe how this system of centres coherently supports the following activities: (1) CMS data quality monitoring, prompt sub-detector calibrations, and time-critical data analysis of express-line and calibration streams; and (2) operation of the CMS computing systems for processing, storage and distribution of real CMS data and simulated data, both at CERN and at offsite centres. We describe the physical infrastructure that has been established, the computing and software systems, the operations model, and the communications systems that are necessary to make such a distributed system coherent and effective.

The KTeV E799 experiment has conducted a search for the rare decay ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}\ensuremath{\gamma}$ via the topology ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}_{D}^{0}\ensuremath{\gamma}$ (where ${\ensuremath{\pi}}_{D}^{0}\ensuremath{\rightarrow}\ensuremath{\gamma}{e}^{+}{e}^{\ensuremath{-}}$). Because of Bose statistics of the ${\ensuremath{\pi}}^{0}$ pair and the real nature of the photon, the ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}\ensuremath{\gamma}$ decay is restricted to proceed at lowest order by the $CP$ conserving direct emission (DE) of an E2 electric quadrupole photon. The rate of this decay is interesting theoretically since chiral perturbation theory predicts that this process vanishes at level $O({p}^{4})$. Therefore, this mode probes chiral perturbation theory at $O({p}^{6})$. In this paper we report a determination of an upper limit of $2.43\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$ (90% CL) for ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}\ensuremath{\gamma}$. This is approximately a factor of 20 lower than previous results.

The Crystal Ball detector at the DORIS II storage ring at DESY has been used to measure the branching ratios for the decay modes τ±→h±π0ν and τ±→h±π0π0ν, where h± is any charged hadron. The results are BR(τ±→h±π0ν) = (22.0±0.8±1.9)%, BR(τ±→h±π0π0ν) = (5.7±0.5+1.0−1.7)%. The first result is in good agreement with the present world average. The decay mode h±π0π0ν is reconstructed in τ decays for the first time. Its branching ratio, however, is somewhat lower than the corresponding world average, and therefore tends to increase the one-prong problem.

We present a measurement of $B({\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}\ensuremath{\gamma})/B({\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma})$, the Dalitz branching ratio, using data taken in 1999 by the E832 KTeV experiment at Fermi National Accelerator Laboratory. We use neutral pions from fully reconstructed ${K}_{L}$ decays in flight; the measurement is based on $\ensuremath{\sim}60$ thousand ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}\ensuremath{\gamma}\ensuremath{\gamma}{e}^{+}{e}^{\ensuremath{-}}\ensuremath{\gamma}$ decays. We normalize to ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}6\ensuremath{\gamma}$ decays. We find $B({\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}\ensuremath{\gamma})/B({\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma})$ $({m}_{{e}^{+}{e}^{\ensuremath{-}}}&gt;15\text{ }\text{ }\mathrm{MeV}/{c}^{2})=[3.920\ifmmode\pm\else\textpm\fi{}0.016(\text{stat})\ifmmode\pm\else\textpm\fi{}0.036(\text{syst})]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$. Using the Mikaelian and Smith prediction for the ${e}^{+}{e}^{\ensuremath{-}}$ mass spectrum, we correct the result to the full ${e}^{+}{e}^{\ensuremath{-}}$ mass range. The corrected result is $B({\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}\ensuremath{\gamma})/B({\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma})=[1.1559\ifmmode\pm\else\textpm\fi{}0.0047(\text{stat})\ifmmode\pm\else\textpm\fi{}0.0106(\text{syst})]%$. This result is consistent with previous measurements, and the uncertainty is a factor of 3 smaller than any previous measurement.

The International Linear Collider (ILC) is a next-generation experimental facility to explore fundamental laws of the Universe. The importance of electron-positron linear colliders as a future experimental facility has been long recognized by the worldwide high energy physics community. A global design team, the Global Design Efforts (GDE), was set up under the International Committee for Future Accelerators (ICFA) for design and coordination of R&D activities of the ILC in 2005, and the ILC Technical Design Report (TDR) was completed in 2013. ICFA then established the Linear Collider Collaboration (LCC) and the Linear Collider Board (LCB) and has continued to support the worldwide efforts for realizing the ILC. Meanwhile, in 2012, KEK and the high energy physics community in Japan proposed that Japan should host the ILC, which was welcomed by the worldwide high energy physics community. Implementation of the ILC project will require strong involvements from international partners due to its scientific importance and large scale. Aspects of international cost sharing and governance of the organization carrying out the ILC project will need to be discussed and agreed at the governmental level. Therefore, KEK established an International Working Group (WG) on the ILC Project in May 2019, inviting scientific experts worldwide* , and asking them to study international aspects of the project implementation from viewpoints of researchers. They were requested to create a report on model of international cost sharing for construction and operation, organization and governance of the ILC Laboratory, and international sharing of the remaining technical preparation. The WG report was submitted to KEK on September 25, 2019. After reviewing the content of the report, KEK decided to make it available within this document entitled “Recommendations on ILC Project Implementation”. This document summarizes the deliberations from researchers’ viewpoints; it does not intend to pre-empt governments and funding agencies. It is hoped that it will be helpful for discussions among governments and funding agencies.

Since the last ICALEPCS, a small multi-region team has developed a reference design model for a control system for the International Linear Collider as part of the ILC Global Design Effort. The scale and performance parameters of the ILC accelerator require new thinking in regards to control system design. Technical challenges include the large number of accelerator systems to be controlled, the large scale of the accelerator facility, the high degree of automation needed during accelerator operations, and control system equipment requiring 'Five Nines' availability. The R&D path for high availability touches the control system hardware, software, and overall architecture, and extends beyond traditional interfaces into the technical systems. Software considerations for HA include fault detection through exhaustive out-of-band monitoring and automatic state migration to redundant systems, while the telecom industry's emerging ATCA standard - conceived, specified, and designed for High Availability - is being evaluated for suitability for ILC front-end electronics.

In this paper the KTeV collaboration reports the analysis of 112.1*10^3 candidate KL->pi+pi-gamma decays including a background of 671+/-41 events with the objective of determining the photon production mechanisms intrinsic to the decay process. These decays have been analyzed to extract the relative contributions of the CP violating bremsstrahlung process and the CP conserving M1 and CP violating E1 direct photon emission processes. The M1 direct photon emission amplitude and its associated vector form factor parameterized as |g_M1|(1+ (a_1/a_2)/(M(rho)^2-M(K)^2+2M(K)*E(gamma)) have been measured to be |g_M1|=1.198 +/- 0.035(stat) +/- 0.086(syst) and a_1/a_2 = -0.738 +/- 0.007(stat) +/- 0.018 (syst) GeV^2/c^2 respectively. An upper limit for the CP violating E1 direct emission amplitude |g_E1| < 0.21 (90% CL) has been found. The overall ratio of direct photon emission (DE) to total photon emission including the bremsstrahlung process (IB) has been determined to be DE/(DE +IB) = 0.689 +/- 0.021 for E(gamma) > 20 MeV.

The decay mode Bs → ψK∗ is suggested as a very good way to measure the Bs mixing parameter xs. These decays can be gathered using a ψ → ℓ+ℓ− trigger. This final state has a well resolved four track decay vertex, useful for good time resolution and background rejection.

Measurements of cosmic rays in the L3 multisampling chambers are presented. The study of tracks with polar angles from 30° < θ < 130° w.r.t. the wires show increasing pulse height like 1/sin θ. Using inclined tracks, we find a ±1.5 cm region of reduced accuracy near the glass supports of the 5.4 m long wires.

Hadronic production of charmed particles in association with muons from their semileptonic decay has been observed in a high-resolution streamer-chamber experiment performed at Fermilab. A miss-distance analysis of the pictures gives a signal of 17.3\ifmmode\pm\else\textpm\fi{}4.7 events. Depending on the production model this corresponds to a range of neutron-nucleon cross sections from 8 to 50 \ensuremath{\mu}b, assuming an ${A}^{\frac{2}{3}}$ dependence.

The observation of CP violation in the B system is one of the great experimental challenges of the next decade. Several B factories are already planned, however, there will be many interesting measurements awaiting a second generation of B exeriments. Studies are being carried out to design a dedicated collider B experiment for the Tevatron at Fermilab. A dedicated B detector at a hadron collider will have a physics reach beyond that of experiments scheduled to begin operation before the end of the decade.

This document describes the simulation framework used in the Snowmass Energy Frontier studies for future Hadron Colliders. An overview of event generation with {\sc Madgraph}5 along with parton shower and hadronization with {\sc Pythia}6 is followed by a detailed description of pile-up and detector simulation with {\sc Delphes}3. Details of event generation are included in a companion paper cited within this paper. The input parametrization is chosen to reflect the best object performance expected from the future ATLAS and CMS experiments; this is referred to as the "Combined Snowmass Detector". We perform simulations of $pp$ interactions at center-of-mass energies $\sqrt{s}=$ 14, 33, and 100 TeV with 0, 50, and 140 additional $pp$ pile-up interactions. The object performance with multi-TeV $pp$ collisions are studied for the first time using large pile-up interactions.

The Crystal Ball detector at thee + e − storage ring DORIS-II has been used to search for radiativeB meson decays, especially of the typeb→sγ. No monoenergetic γ-lines have been found in the inclusive photon spectrum from У(4S) decays, and upper limits are obtained for radiative decays ofB mesons to various strange mesons and to theD *. Integrating the photon spectrum over the corresponding energy range, we find $$BR(B \to \gamma X)< 2.8 \times 10^{ - 3} ,$$ at 90% confidence level for the mass range 892 MeV ≦M X ≦2045 MeV.