Michael Wayne Arenton

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 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

We present density-matrix elements and single-spin correlations for the reaction ${p}_{\ensuremath{\uparrow}}$p\ensuremath{\rightarrow}p${\ensuremath{\pi}}^{+}$n at 1.18, 1.47, 1.71, and 1.98 GeV/c, using both longitudinal and transverse beam polarizations. For the ${p}_{\ensuremath{\uparrow}}$p\ensuremath{\rightarrow}${\ensuremath{\Delta}}^{++}$n subprocess we find quite different energy dependence for the helicity-(1/2) and helicity-(3/2) ${\ensuremath{\Delta}}^{++}$-production asymmetries. The helicity-(1/2) asymmetry has ${p}_{\mathrm{lab}}$ dependence similar to the polarization in ${p}_{\ensuremath{\uparrow}}$p\ensuremath{\rightarrow}${\ensuremath{\pi}}^{+}$d, while the helicity-(3/2) asymmetry changes sign between 1.18 and 1.47 GeV/c. By fitting the production angle dependence of the spin correlations, we obtain joint moments which are easily related to the partial-wave structure. We have carried out a partial-wave analysis with the moments data. We find that the production wave intensities are qualitatively consistent with the elastic phase-shift analyses, and the phases vary smoothly with ${p}_{\mathrm{lab}}$. From the absence of Breit-Wigner phase behavior, we conclude that the dinucleon resonances seen in the pp elastic waves are not true coupled-channel Briet-Wigner states in NN and N\ensuremath{\Delta}.

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).

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 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.

New experimental information is presented about the effect of a nucleus on partons which have undergone a hard scatter. We have observed clear dijet events from 400 GeV / c p-nucleus interactions and compared them to dijets from pp interactions. Our results show that the angular width of the individual jets is only slightly affected by the presence of the nucleus, but the acoplanarity of the jet pairs is sharply increased.

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).

Plans and first results from Fermilab Experiment 853 are presented. E853 is an experiment to test the feasibility and efficiency of extracting a low-intensity beam from the halo of the Tevatron using channeling in a bent silicon crystal. The motivation of the experiment is to apply crystal extraction to trans-TeV accelerators like the LHC. Channeling developments related to crystal extraction and some early results from accelerator studies at the Tevatron are presented.

We searched for the appearance of π+π− pairs with invariant mass ≥648MeV/c2 in a neutral beam. Such an observation could signify the decay of a long-lived light neutral particle. We find no evidence for this decay. Our null result severely constrains the existence of an R0 hadron, which is the lightest bound state of a gluon and a light gluino (g˜g), and thereby also the existence of a light gluino. Depending on the photino mass, we exclude the R0 in the mass and lifetime ranges of 1.2–4.6GeV/c2 and 2×10−10–7×10−4s, respectively.Received 18 July 1997DOI:https://doi.org/10.1103/PhysRevLett.79.4083©1997 American Physical Society

We present density-matrix elements and single-spin correlations for the reaction ${p}_{\ensuremath{\uparrow}}$p\ensuremath{\rightarrow}p${\ensuremath{\pi}}^{+}$n at 3, 4, 6, and 11.75 GeV/c, using both longitudinal and transverse beam polarizations. For small momentum transfers, the spin correlations are mainly due to off-shell ${\ensuremath{\pi}}^{+}$p elastic scattering, while for larger t there are large polarization effects associated with the production dynamics for ${p}_{\ensuremath{\uparrow}}$p\ensuremath{\rightarrow}${\ensuremath{\Delta}}^{++}$n. Comparison of longitudinal and transverse polarization correlations suggests that the ${\ensuremath{\Delta}}^{++}$-production spin effects are due mainly to unnatural-parity exchanges. We present a model-dependent amplitude analysis, and extract the energy dependence of the natural- and unnatural-parity-exchange contributions.

Ensuring the radiation hardness of PbWO4 crystals was one of the main priorities during the construction of the electromagnetic calorimeter of the CMS experiment at CERN. The production on an industrial scale of radiation hard crystals and their certification over a period of several years represented a difficult challenge both for CMS and for the crystal suppliers. The present article reviews the related scientific and technological problems encountered.

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 analyzing power Ay0 in the reaction p↑p→dπ+ has been measured using the polarized proton beam at Argonne National Laboratory's zero gradient synchrotron. Data were taken at beam momenta of 1.17, 1.47, 1.70, and 1.96 GeV/c and for pion center of mass angles from 8° to 163°.

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.

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 ${R}^{0}$.

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.

In a study of large-${p}_{T}$ jet production in 200-GeV/c \ensuremath{\pi}p and pp collisions, we find evidence for pion-induced dijet events with little or no forward energy flow. The rate and characteristics of these events are compatible with the predictions of Berger and Brodsky for higher-twist processes. No corresponding signal is seen in pp collisions.

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 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.

15 000 events of the reaction $p_{\ensuremath{\uparrow}}p\ensuremath{\rightarrow}p{K}^{+}{K}^{\ensuremath{-}}p$ were obtained at 11.75 GeV/c using the Zero Gradient Synchrotron polarized proton beam and the Effective Mass Spectrometer. This event sample includes 1500 events of $p_{\ensuremath{\uparrow}}p\ensuremath{\rightarrow}p\ensuremath{\varphi}p$. The characteristics of $\ensuremath{\varphi}$ production are examined. The $t$ distribution is found to be quite shallow (exponential slope parameter 3.3 Ge${\mathrm{V}}^{\ensuremath{-}2}$). The cross section for $\ensuremath{\varphi}$ production is compared to that for $\mathrm{pp}\ensuremath{\rightarrow}p\ensuremath{\omega}p$ measured in the same apparatus. A ratio of $\frac{\ensuremath{\varphi}}{\ensuremath{\omega}}$ cross sections of 0.010\ifmmode\pm\else\textpm\fi{}0.002 is found, substantially larger than the value of 0.002 predicted by the Okubo-Zweig-Iizuka rule. Upper limits are set for the production of narrow states, possibly of a $\mathrm{qqqq}\overline{q}$ quark composition, decaying into $\ensuremath{\varphi}p$, ${K}^{+}{K}^{\ensuremath{-}}p$, or ${K}^{+}{Y}^{*}(1520)$.

The invariant cross section for production of jet pairs in 400-GeV/c pp interactions has been measured as a function of pT in the pT range 4 to 9 GeV/c. The results are in good agreement with predictions of a perturbative QCD model. Details of the experiment and the procedures used to extract the jet signal are given.Received 9 April 1984DOI:https://doi.org/10.1103/PhysRevD.31.984©1985 American Physical Society

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.

A search was made for five-quark "pseudobaryon" and four-quark baryonium states with a 1000-event sample of the reaction $\mathrm{pp}\ensuremath{\rightarrow}\mathrm{pp}\overline{p}p$ at 11.75 GeV/c. For states with widths \ensuremath{\lesssim} 10 MeV/${\mathit{c}}^{2}$ and masses ${M}_{\overline{p}p}&lt;2.2$ GeV/${\mathit{c}}^{2}$ and ${M}_{\mathrm{pp}\overline{p}}&lt;3.4$ GeV/${\mathit{c}}^{2}$, upper limits on the product of the cross section and the branching ratio for forward-hemisphere production are measured to be \ensuremath{\sim} 15 nb.

Studies have been done and continue on the design and construction of a Shashlik detector using Radiation hard quartz capillaries filled with wavelength shifting liquid to collect the scintillation light from LYSO crystals for use as a calorimeter in the Phase II CMS upgrade at CERN. The work presented here focuses on the studies of the capillaries and liquids that would best suit the purpose of the detector. Comparisons are made of various liquids, concentrations, and capillary construction techniques will be discussed.

Results are presented from a calorimeter study on the production of jets in large-ET proton-nucleus collisions at 400 GeV/c. Jet-like large-pT events from eight nuclear targets are seen with a special jet trigger. As previously observed, the cross section for such events increases slightly faster than the atomic number, much like in the production of large-pT single hadrons. Data on energy flows and multiplicities suggest that a heavy nucleus does not significantly widen the angular distribution of the beam remmants. In the central region the particle flow in hard nuclear collisions is similar to that in soft nuclear collisions.

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

The invariant cross section for production of jet pairs in 400-GeV/c pp interactions has been measured as a function of pT in the pT range 4 to 9 GeV/c. The results are in good agreement with predictions of perturbative QCD models.Received 9 May 1984DOI:https://doi.org/10.1103/PhysRevLett.53.1988©1984 American Physical Society

In an experiment performed at Fermilab we have studied the production of high pt hadron jets from 400 GeV/c pp interactions. A large solid-angle, towered calorimeter was used to trigger and reconstruct the jet events. We report results for inclusive single-jet production and compare those results with QCD predictions and results obtained at the ISR and the SPS Collider.

Samples of the reaction $p_{\ensuremath{\uparrow}}p\ensuremath{\rightarrow}p\ensuremath{\omega}p$, consisting of 20 000 and 1000 events at 11.75 and 6 GeV/c, respectively, were obtained using the Zero Gradient Synchrotron polarized proton beam and the Effective Mass Spectrometer. A narrow enhancement near threshold is seen in the $\ensuremath{\omega}p$ mass distribution. The $t$ distribution of this enhancement shows a pronounced dip near $t=\ensuremath{-}0.2$ Ge${\mathrm{V}}^{2}$ at both beam momenta, suggesting that $\ensuremath{\omega}$ exchange is the dominant production mechanism. The joint-decay-angular-distribution moments and polarization correlations have been determined as functions of $\ensuremath{\omega}p$ mass. Amplitude analysis of these moments indicates that the low-mass enhancement is due to the high-mass tails of spin-parity ${\frac{3}{2}}^{\ensuremath{-}}$ and ${\frac{3}{2}}^{+}$ states below $\ensuremath{\omega}p$ threshold. Polarization correlations consistent with zero provide evidence for the lack of resonant behavior in the low-mass enhancement itself.

In this paper the KTeV collaboration reports the analysis of 112.1×103 candidate KL→π+π−γ 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+a1/a2(Mρ2−MK2)+2MKEγ) have been measured to be |g˜M1|=1.198±0.035(stat)±0.086(syst) and a1/a2=−0.738±0.007(stat)±0.018(syst) GeV2/c2 respectively. An upper limit for the CP violating E1 direct emission amplitude |gE1|≤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 Eγ≥20 MeV.Received 17 March 2006Corrected 9 August 2006DOI:https://doi.org/10.1103/PhysRevD.74.032004©2006 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.

Abstract We have built and operated a set of two low-mass cylindrical multiwire proportional chambers to detect recoil protons emerging from a liquid hydrogen target. The chambers were 20 and 40 cm in diameter and ∼ 50 cm long, with axes and anode wires parallel to the beam direction. “Magic gas” was used to ensure that avalanches measured the points of closest approach for particle trajectories, which were often at small angles to the anode wires. Azimuthal coordinates were provided by the 2 mm-spaced anode wires (at positive high voltage); longitudinal coordinates were obtained from 4 mm-wide circular cathode strips perpendicular to the anode wires, read out by 12 nsec/cm delay lines. For single-track events, resolutions better than 1 mm rms were obtained for both coordinates.

Using the E609 calorimeter system, we have measured longitudinal energy flow in hard pA collisions which yield dijet final states. The mean laboratory energy flow into the nuclear target (backward) region, nlab < 2.83, minus the value for pp collisions is found to vary as A0.33 ± 0.12, and reaches a value of 50±8 GeV for Pb. The observed probability distribution of energy flow indicates that the energy transfer to a heavy nucleus seldom fluctuates to small values. We also find that the A dependence of the dijet production cross section depends sensitively upon the energy flow to the target region.

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

This Letter is the first report of the K{L}-->pi{+/-}e{-/+}nue{+}e{-} decay. Based on 19 208+/-144 events, we determine the branching fraction, B(K{L}-->pi{+/-}e{-/+}nue{+}e{-}M_{e{+}e{-}}>5 MeV/c{2},E{e{+}e{-}}{*}>30 MeV)=(1.285+/-0.041)x10{-5}, and Gamma(K{e3ee}M{e{+}e{-}}>5 MeV/c{2})/Gamma(K{e3})=[4.57+/-0.04(stat)+/-0.14(syst)]x10{-5}. This ratio agrees with a theoretical prediction based on chiral perturbation theory (ChPT) calculated to O(p{4}). The measured kinematical distributions agree with those predicted by just ChPT O(p{4}), but show significant disagreement with ones predicted by leading-order ChPT.

Results on the performance and details of the design of an iron-scintillator hadron calorimeter are presented. A full absorption array of 87 calorimeter modules was assembled and tested at Fermilab. The central core of this array consisted of 48 modules with 2.8 cm iron sampling thickness by 10-13 cm width arranged in towers of modules three deep along the beam (shower) axis for a total of about 8 absorption lengths. The energy resolution of the calorimeter is given by 30%/√E for electrons and 92%/√E for hadrons. This resolution is compared with previous results and is found to be in good agreement with the expected resolution for this sampling thickness. The position resolution for single hadron showers is about 2 cm.

In a 400 GeV/c fixed target experiment using a set of geometrical calorimeter triggers we have determined a cross section for pp collisions producing two high PT coplanar clusters. This cross section was determined without using jet-finding algorithms or appealing to QCD Monte Carlo calculations. Corrections to the data were made by studying hardware triggers designed for that purpose or using experimental data from e+e− colliders. The magnitude of the experimental cross section and the PT slope both agree reasonably well with theoretical QCD predictions for parton-parton scattering that combine non-scaling behavior with fits to recent data from ep, μp, and vp experiments.

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 rationale for pursuing beauty physics at the SSC in a fixed target configuration is described. The increased beauty production cross section at the SSC, combined with high interaction rate capability of the proposed detector, results in 1010–11 produced BB events per year. The long decay length of the B hadrons (≌10 cm) allows direct observation of B decays in the high resolution silicon microstrip vertex detector. To optimize the operation of the proposed beauty spectrometer and the SSC, parasitic extraction of attendant or artificially generated large amplitude protons using crystal channeling is proposed and explored. The large sample of fully reconstructed B events allows detailed studies various CP violating decays with requisite statistics to confront the standard model. The CP physics potentials of the proposed experiment is evaluated and compared with alternative approaches, such as asymmetric e+e− B Factories and specialized hadron colliders.

We have obtained 1400 events of the baryon-exchange reaction $\mathrm{pp}\ensuremath{\rightarrow}\ensuremath{\Lambda}p{K}^{+}$ using the ANL Zero Gradient Synchrotron 11.75-GeV/c polarized proton beam and the effective-mass spectrometer. A search for enhancements in the $\ensuremath{\Lambda}p$ mass spectrum has been made. No enhancements are observed; in particular, the narrow $\ensuremath{\Lambda}p$ enhancement at 2.13 GeV seen in ${K}^{\ensuremath{-}}d\ensuremath{\rightarrow}\ensuremath{\Lambda}p{\ensuremath{\pi}}^{\ensuremath{-}}$ is not observed. We establish limits on the production of narrow states of \ensuremath{\sim} 10 nb. Also, 100000 events of the forward reaction $\mathrm{pp}\ensuremath{\rightarrow}\ensuremath{\Lambda}{K}^{+}p$ were examined and no narrow $\ensuremath{\Lambda}p$ enhancements are seen.

We present angular distributions and, for the first time, single-spin correlations in the diffraction-dissociation reaction ${p}_{\ensuremath{\uparrow}}$p\ensuremath{\rightarrow}p${\ensuremath{\pi}}^{+}$${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$p, for small momentum transfers between the polarized beam and the (p${\ensuremath{\pi}}^{+}$${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$) system, at 11.75 GeV/c. The only structures seen in our 2\ifmmode\times\else\texttimes\fi{}${10}^{6}$-event sample turn out to be the well-known threshold enhancement in \ensuremath{\Delta}\ensuremath{\pi} and the N(1700), which appears to involve both \ensuremath{\Delta}\ensuremath{\pi} and N(1520)\ensuremath{\pi}. The production process exhibits a slope-mass correlation and patterns of helicity nonconservation seen in higher-energy diffractive processes. We also see evidence for a complex helicity structure in the spin correlations. We show that the threshold enhancement is unambiguously S wave in character, while the N(1700) appears to be a mix of states. The overall similarities between our data and those at higher energies, together with the rich structures contained in the angular-distribution correlations (we measure 315 joint moments in each mass and t bin), make our data base highly relevant for theoretical analysis of exclusive diffraction.

The status of CP violation measurements in the KTeV experiment is presented. We present the current status of the measurement of Re(ε′/ε). Preliminary results on a T-odd angular asymmetry in the rare decay KL→π+π−e+e− are presented.

The KTeV E799 experiment has conducted a search for the rare decay K{sub L} {yields} {pi}{sup 0}{sup 0}{gamma} via the topology K{sub L} {yields} {pi}{sup 0}{pi}{sup 0}{sub D}{gamma} (where {pi}{sup 0}{sub D} {yields} {gamma}e{sup +}e{sup -}). Due to Bose statistics of the {pi}{sup 0} pair and the real nature of the photon, the K{sub L} {yields} {pi}{sup 0}{pi}{sup 0}{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{sup 4}). Therefore, this mode probes chiral perturbation theory at O(p{sup 6}). In this paper we report a determination of an upper limit of 2.43 x 10{sup -7} (90% CL) for K{sub L} {yields} {pi}{sup 0}{pi}{sup 0}{gamma}. This is approximately a factor of 20 lower than previous results.

This Technical Memorandum (TM) summarizes the Fermilab Test Beam operations for FY2017. It is one of a series of annual publications intended to gather information in one place. In this case, the information concerns the individual experiments that ran at FTBF and are listed in Table 1. Each experiment section was prepared by the relevant authors, and was edited for inclusion in this summary.

Recent results on rare K decays from KTeV and NA48 are reviewed.

The {xi}{sup 0} 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 {xi}{sup 0} beta decay mode and yields a value for the ratio of decay rates {gamma}({xi}{sup 0}{yields}{sigma}{sup +}{mu}{sup -}{nu}{sub {mu}})/{gamma}({xi}{sup 0}{yields}{sigma}{sup +}e{sup -}{nu}= {sub e}) of [1.8{sub -0.5}{sup +0.7}(stat){+-}0.2(syst)]x10{sup -2}. This is in agreement with the SU(3) flavor symmetric quark model.

We have observed the decay $K_L\to \mu^+\mu^- \gamma \gamma$ at the KTeV experiment at Fermilab. This decay presents a formidable background to the search for new physics in $K_L\to\pi^0\mu^+\mu^-$. The 1997 data yielded a sample of 4 signal events, with an expected background of 0.155 $\pm$ 0.081 events. The branching ratio is ${\mathcal B}(K_L\to \mu^+\mu^- \gamma \gamma$) $ = (10.4^{+7.5}_{-5.9} {\rm (stat)} \pm 0.7 {\rm (sys)})\times 10^{-9}$ with $m_{\gamma\gamma} \geq 1 {\rm MeV/c}^2$, consistent with a QED calculation which predicts $(9.1\pm 0.8)\times 10^{-9}$.

An overview is presented of the talks in the working group on Goldstone Bosons. Topics touched on are CP-violation in the Kaon system, rare Kaon decays, $\pi\pi$-scattering, $\phi$-meson decays, scalar mesons, form-factors and polarizabilities, $\eta$-decays, chiral symmetry breaking, connections with QCD at short-distances and effective theories for electroweak physics.

A preliminary analysis of an experiment designed as a sensitive dibaryon resonance search in the reaction pp..-->..p..pi../sup +/n is presented. At 2 GeV/c incident momentum, 440,000 unambiguously reconstructed events were obtained. In this preliminary analysis, the results are reported of a search of the pn mass spectrum for evidence of chain decays of possible dibaryon resonances, i.e. pp..-->..d/sup **/, d/sup **/..-->..d/sup **/..pi../sup +/, d/sup */..-->..pn. No evidence of narrow peaks (less than or equal to 7 MeV) is seen in the data for cross-section-times-branching-ratio greater than 50 ..mu..b.

Results of an experiment measuring the production of charmonium states with 300 GeV/c π + , π - , p and [Formula: see text] beams on a Li target are presented. Total and differential cross sections for production of J/ψ, ψ′ and χ states are presented. The separation of the χ signal into the χ 1 and χ 2 states is discussed. The fraction of J/ψ's that result from direct production is derived.

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We report on a new measurement of the decay K{sub L}{r_arrow}{pi}{sup 0}{gamma}{gamma} by the KTeV experiment at Fermilab. We determine the K{sub L}{r_arrow}{pi}{sup 0}{gamma}{gamma} branching ratio to be (1.68{plus_minus}0.07{plus_minus}0.08){times}10{sup {minus}6} . Our data show the first evidence for a low-mass {gamma}{gamma} signal as predicted by recent O(p{sup 6}) chiral perturbation calculations which include vector meson exchange contributions. From our data, we extract a value for the effective vector coupling a{sub V}={minus}0.72{plus_minus}0.05{plus_minus}0.06 . {copyright} {ital 1999} {ital The American Physical Society }

We report the first branching fraction measurement of the decay K{sub L}{r_arrow}{pi}{sup +}{pi}{sup {minus}}e{sup +}e{sup {minus}} . With a sample of 46 candidates, and an expected background level of 9.4 events, the branching fraction is determined to be B(K{sub L}{r_arrow}{pi}{sup +}{pi}{sup {minus} }e{sup +}e{sup {minus}})=[3.2{plus_minus}0.6 (stat){plus_minus}0.4(syst) ]{times}10{sup {minus}7} . This measurement was carried out as part of the Fermilab KTeV (E799-II) experiment and is in good agreement with the expectations from the mechanisms of direct emission and inner bremsstrahlung. {copyright} {ital 1998} {ital The American Physical Society}

T. Alexopoulos, 1 L. Antoniazzi, 2 M. Arenton, 3 H. C. Ballagh, 4 H. Bingham, 4 A. Blankman, 5 M. Block, 6 A. Boden, 7 G. Bonomi, 2 Z. L. Cao, 3 T. Y. Chen, 8 K. Clark, 9 D. Cline, 7 S. Conetti, 3 M. Cooper, 10 G. Corti, 3 B. Cox, 3 P. Creti, 11 C. Dukes, 3 C. Durandet, 1 V. Elia, 11 A. R. Erwin, 1 L. Fortney, 12 V. Golovatyuk, 11 E. Gorini, 11 F. Grancagnolo, 11 K. Hagan-Ingram, 3 M. Haire, 13 P. Hanlet, 3 M. He, 14 G. Introzzi, 2 M. Jenkins, 9 D. Judd, 13 W. Kononenko, 5 W. Kowald, 12 K. Lau, 15 A. Ledovskoy, 3 G. Liguori, 2 J. Lys, 4 P. O. Mazur, 16 A. McManus, 3 S. Misawa, 4 G. H. Mo, 15 C. T. Murphy, 16 K. Nelson, 3 M. Panareo, 11 V. Pogosian, 3 S. Ramachandran, 7 J. Rhoades, 7 W. Selove, 5 R. P. Smith, 16 L. Spiegel, 16 J. G. Sun, 3 S. Tokar, 17 P. Torre, 2 J. Trischuk, 18 L. Turnbull, 13 D. E. Wagoner, 13 C. R. Wang, 14 C. Wei, 12 W. Yang, 16 N. Yao, 8 N. J. Zhang, 14 and B. T. Zou 12 University of Wisconsin, Madison, Wisconsin 53706 University and INFN of Pavia, Pavia, Italy University of Virginia, Charlottesville, Virginia 22901 University of California at Berkeley, Berkeley, California 94720 University of Pennsylvania, Philadelphia, Pennsylvania 19104 Northwestern University, Evanston, Illinois 60208 University of California at Los Angeles, Los Angeles, California 90024 Nanjing University, Nanjing, People’s Republic of China University of South Alabama, Mobile, Alabama 36688 Vanier College, Montreal, Quebec, Canada H4L 3X9 University and INFN of Lecce, Lecce, Italy Duke University, Durham, North Carolina 27706 Prairie View A&M, Prairie View, Texas 77446 Shandong University, Jinan, Shandong, People’s Republic of China University of Houston, Houston, Texas 77204 Fermilab, Batavia, Illinois 60510 Comenius University, Bratislava, Slovakia McGill University, Montreal, Quebec, Canada H3A 2T8 ~Received 30 July 1996!

We have recently completed the first part of running for experiment E-609 at Fermilab. The E-609 hadron jet experiment uses a 132-segment 8-steradian full azimuth calorimeter with tower structure. Additional parts of the apparatus are described in the paper. A novel triggering system allowed us to take data with many different kinds of triggers simultaneously. We give a preliminary report on data obtained in 400 GeV pp collisions, concentrating on data from two triggers, both of which have no special geometrical requirement for the form of the transverse energy deposition. One of these was a global total E-transverse trigger; the other was a 2-high trigger, which required that 2 or more calorimeter segments (any 2) each give a signal larger than about 1.0 GeV/c. This report further concentrates on the data sample with total transverse energy above 11 GeV. We will present results concerning planarity distributions as well as theta-phi energy flow, for these events. For the globally triggered events in this kinematic region, only a few percent show clear di-jet structure, with clustering, co-planarity, and concentration of high-p/sub T/ fragments near the jet axes. For the 2-high events however, at this E-transverse, approximately 30 percent of the events show di-jet structure. The 2-high events constitute only about 15 percent of the global events, but contain virtually all the events which show this clear di-jet structure. Details of the analysis are presented, including studies of whether the features of the di-jet events can be explained by simple random fluctuations.

Experiment 609 at Fermilab is a study of the properties of high-p/sub t/ collisions using a large segmented hadron calorimeter. The calibration and monitoring of such a large calorimeter array is a difficult undertaking. This paper describes the systems developed by E609 for automatic monitoring of the phototube gains and performance of the associated electronics.