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Observation of the Decay K{sup +} yields P{sup +} v...

Description: We have observed 1 event consistent with the signature expected of the rare decay of a positive kaon to a positive pion and a neutrino anti-neutrino pair. In the examined momentum region of 211 to 230 MeV/c in the center of mass of the kaon we estimated the backgrounds to be about 0.08 &plusmn; 0.03 events. From this observation we estimate the branching ratio to be 4.2<SUP>+9.7</SUP><SUB>-3.5</SUB> x 10<SUP>-10</SUP>. In this presentation I will explain the experiment, and the analysis techniques. I will also discuss the expected improvements in the near future from the analysis of new data sets.
Date: May 21, 1999
Creator: Diwan, M.V.
Partner: UNT Libraries Government Documents Department

Absolute Decay Rate from K<sub>2</sub><sup>0</sup>→π<sup>+</sup> + π<sup>-</sup> + π<sup>0</sup> and the barDELTA I over→bar = 1/2 Rule

Description: In this letter the author describes a measurement of the absolute decay rate {Gamma}{sub 2}({+-}0) {approx_equal} {Gamma}(K{sub 2}{sup 0} {yields} {pi}{sup +}{pi}{sup -}{pi}{sup 0}). The result is based on 16 events of the type {pi}{sup -} p {yields} {Lambda}K{sup 0} followed by {Lambda} {yields} p{pi}{sup -} and K{sub 2}{sup 0} {yields} {pi}{sup +}{pi}{sup -}{pi}{sup 0}, and 2608 double-vec events {pi}{sup -} p {yields} {Lambda}K{sup 0} with {Lambda} {yields} p{pi}{sup -} and K{sub 1}{sup 0} {yields} {pi}{sup +}{pi}{sup -}.
Date: February 4, 1964
Creator: Stern, Donald; Binford, Thomas O.; Lind, V. Gordon; Anderson, Jared A.; Crawford, Jr, Frank S. & Golden, Robert L.
Partner: UNT Libraries Government Documents Department

Evidence for {Kappa}{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}}

Description: The first observation of the decay {Kappa}{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}} has been reported. The E787 experiment presented evidence for the {Kappa}{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}} decay, based on the observation of a single clean event from data collected during the 1995 run of the AGS (Alternating Gradient Synchrotron at Brookhaven National Laboratory). The branching ratio indicated by this observation, {Beta}({Kappa}{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}}) = 4.2{sub {minus}3.5}{sup +9.7} {times} 10{sup {minus}10}, is consistent with the Standard Model expectation although the central experimental value is four times larger. The final E787 data sample, from the 1995--98 runs, should reach a sensitivity of about five times that of the 1995 run alone. A new experiment, E949, has been given scientific approval and should start data collection in 2001. It is expected to achieve a sensitivity of more than an order of magnitude below the prediction of the Standard Model.
Date: December 31, 1998
Creator: Kettell, S.
Partner: UNT Libraries Government Documents Department

919: Evidence for K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}} from E787

Description: A collaboration from KEK, INS, Osaka, TRIUMF, Princeton, and BNL is currently running E787 at the AGS. The experiment is designed primarily to search for the rare decay K{sup +} {yields} {pi}{sup +}{nu}{bar {nu}}, with an expected branching ratio of {approximately} 10{sup {minus}10}. The authors report evidence that they have observed this decay. They also discuss the future outlook for the experiment.
Date: December 1, 1997
Creator: Frank, J.S. & Collaboration, E787
Partner: UNT Libraries Government Documents Department

RARE K+ DECAYS FROM EXPERIMENT E787.

Description: This paper presents the latest results from experiment E787, at Brookhaven National Laboratory, on K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}} and radiative K{sup +} decays. The result for K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}} uses data collected in runs taken during 1995, 1996 and 1997. In addition, they discuss plans for future measurements of K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}}.
Date: October 9, 2000
Creator: JAIN,V.
Partner: UNT Libraries Government Documents Department

Hard exclusive electroproduction of pions

Description: The authors investigate the exclusive electroproduction of {pi}{sup +} mesons from nucleons. To leading twist, leading order {alpha}{sub s} accuracy the corresponding production amplitude can be decomposed into pseudovector and pseudoscalar parts. Both can be expressed in terms of quark double distribution functions of the nucleon. While the pseudovector contribution is connected to ordinary polarized quark distributions, the pseudoscalar part can be related to one pion t-channel exchange. They observe that the pseudovector part of the production amplitude is important at x &lt; 0.1. On the other hand, for 0.1 &lt; x &lt; 0.4 contributions from one pion exchange dominate.
Date: December 1, 1998
Creator: Mankiewicz, L.; Piller, G. & Radyushkin, A.
Partner: UNT Libraries Government Documents Department

Observation of the decay K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}}

Description: We have observed 1 event consistent with the signature expected of the rare decay of a positive kaon to a positive pion and a neutrino anti-neutrino pair. In the examined momentum region of 211 to 230 MeV/c in the center of mass of the kaon we estimated the backgrounds to be about 0.08 {+-} 0.03 events. From this observation we estimate the branching ratio to be 4.2{sub {minus}3.5}{sup +9.7} x 10{sup {minus}10}. In this presentation I will explain the experiment, and the analysis techniques. I will also discuss the expected improvements in the near future from the analysis of new data sets.
Date: January 5, 1999
Creator: DIWAN,M.B.
Partner: UNT Libraries Government Documents Department

Hadronic spectra in Au+Au reactions at 11.6 A{center_dot}GeV/c: Rapidity and m{sub t} distributions

Description: In central Au+Au collisions, the rapidity distribution of measured protons integrated over {ital m{sub t}} indicates almost complete stopping, hence high baryon density. For a given rapidity, low mt enhancement has been observed for {pi}{sup -} production over that of {pi}{sup +}. The Coulomb interaction with the co-moving medium has been invoked to explain the difference. The inverse slope parameters of the {ital m{sub t}} spectra for protons and deuterons increases from peripheral to central events, while the parameter for pions stays the same. This may indicate that a radial expansion follows the high density stage of the reaction.
Date: December 31, 1996
Creator: Chen, Ziping & Collaboration, E866
Partner: UNT Libraries Government Documents Department

Evidence for K{sup +} {r_arrow} {pi}{sup +} {nu}{anti {nu}}

Description: The decay K{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}} has been observed for the first time. The E787 experiment has presented evidence for the K{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}} decay, based on the observation of a single clean event from data collected during the 1995 run of the AGS (Alternating Gradient Synchrotron at Brookhaven National Laboratory). The branching ratio indicated by this observation, B(K{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}}) = 4.2{sub {minus}3.5}{sup +9.7} {times} 10{sup {minus}10}, is consistent with the Standard Model expectation although the central experimental value is four times larger. The final E787 data sample, from the 1995--99 runs, should reach a sensitivity of about eight times that of the 1995 run alone. A new experiment, E949, has been approved to run, starting in the year 2000, and is expected to achieve a sensitivity of more than an order of magnitude below the prediction of the Standard Model.
Date: December 31, 1998
Creator: Kettell, S.; Collaboration, E787 & Collaboration, E949
Partner: UNT Libraries Government Documents Department

Spin Physics at JLAB in the Resonance Region

Description: I will discuss recent results from Jefferson Lab on the measurement of inclusive spin structure functions in the nucleon resonance region using polarized ammonia NH{sub 3} and polarized {sup 3}He targets. Preliminary results on the first moment of g{_}1(x,Q{sup 2}) for protons, and the generalized Gerasimov-Drell-Hearn integral for neutrons are presented. In addition, first double polarization data on exclusive electroproduction of pi{sup +} for polarized protons will be discussed.
Date: May 1, 2001
Creator: Burkert, V.
Partner: UNT Libraries Government Documents Department

CAN RECENT CHARGE FLUCTUATION CALCULATIONS BE A RELIABLE SIGNAL FOR A QGP AT RHIC?

Description: The recent papers of Jeon and Koch[l] and Asakawa, Heinz and Muller[2] propose that the event by event fluctuations of the ratio of the positively charged and negatively charged pions could provide a distinct signal for a QGP at RHIC/LHC due to differences in those from the QGP phase, and the Hadron Gas Phase. In this paper we point out that aside from the questionability of the many assumptions in the treatment used, even following their approach there are other effects not considered, e.g. color charge fluctuations which we show could significantly or completely wash out the proposed signal. Therefore lack of observation of these charge fluctuation signals cannot lead one to conclude that a QGP is not formed at RHIC. A general discussion of experimental requirements for observation of such signals (if they exist) and how to interpret them is included.
Date: August 1, 2001
Creator: LINDENBAUM, S.J. & LONGACRE, R.S.
Partner: UNT Libraries Government Documents Department

Review of charm lifetimes

Description: A review of the latest experimental results on charm particle lifetimes is presented. The most significant update is that the D{sub s}{sup +} lifetime is conclusively larger than the D{sup 0} lifetime and signifies that W-exchange/W-annihilation contributions are large. Using new high statistics data on D{sup +} {r{underscore}arrow} K{sup +}{pi}{sup +}{pi}{sup {minus}} together with the D{sub s}{sup +} lifetime and some assumptions, one can phenomenologically extract the strength of the W-exchange contribution in D{sup 0} decays and of W-annihilation in D{sub s}{sup +} decays. These are larger than or at the limit of theoretical expectations using QCD-based operator production expansion techniques.
Date: January 6, 2000
Creator: Cheung, H.W.K.
Partner: UNT Libraries Government Documents Department

Direct flow in 10.8 GeV/nucleon Au+Au collisions measured in experiment E917 at the AGS.

Description: Analysis of directed flow observable for protons and pions from Au+Au collisions at 10.8 GeV/nucleon from experiment E917 at the AGS is presented. Using a Fourier series expansion, the first Fourier component, {nu}{sub 1},was extracted as a function of rapidity for mid-central collisions (17-24%). Clear evidence for positive directed flow is found in the proton data, and a weak, possibly negative directed flow signal is observed for {pi}{sup +} and {pi}{sup {minus}}.
Date: May 19, 1999
Creator: Back, B. B.; Betts, R. R.; Britt, H. C.; Chang, J.; Chang, W. C.; Gillitzer, A. et al.
Partner: UNT Libraries Government Documents Department

Observation of CP Violation in B0 to K+pi- and B0 to pi+pi-

Description: The authors report observations of CP violation in the decays B{sup 0} {yields} K{sup +}{pi}{sup -} and B{sup 0} {yields} {pi}{sup +}{pi}{sup -} in a sample of 383 million {Upsilon}(4S) {yields} B{bar B} events. They find 4372 {+-} 82 B{sup 0} {yields} K{sup +}{pi}{sup -} decays and measure the direct Cp-violating charge asymmetry {Alpha}{sub K{pi}} = -0.107 {+-} 0.018(stat){sub -0.004}{sup +0.007}(syst), which excludes the CP-conserving hypothesis with a significance of 5.5 standard deviations. In the same sample they find 1139 {+-} 49 B{sup 0} {yields} {pi}{sup +}{pi}{sup -} decays and measure the CP-violating asymmetries S{sub {pi}{pi}} = -0.60 {+-} 0.11(stat) {+-} 0.03(syst) and C{sub {pi}{pi}} = -0.21 {+-} 0.09(stat) {+-} 0.02(syst). CP conservation in B{sup 0} {yields} {pi}{sup +}{pi}{sup -} (S{sub {pi}{pi}} = C{sub {pi}{pi}} = 0) is excluded at a confidence level 1-C.L. = 8 x 10{sup -8}, corresponding to 5.4 standard deviations.
Date: March 14, 2007
Creator: Aubert, B.
Partner: UNT Libraries Government Documents Department

Observation of $\Upsilon(4S) decays to$\pi^+pi^-\Upsilon(1S)$ and $\pi^+pi^-\Upsilon(1S)$

Description: The authors present the first measurement of {Upsilon}(4S) decays to {pi}{sup +}{pi}{sup -} {Upsilon}(1S) and {pi}{sup +}{pi}{sup -} {Upsilon}(2S) based on a sample of 230 x 10{sup 6} {Upsilon}(4S) mesons collected with the BABAR detector. They measure the product branching fractions {Beta}({Upsilon}(4S) {yields} {pi}{sup +}{pi}{sup -} {Upsilon}(1S)) x {Beta}({Upsilon}(1S) {yields} {mu}{sup +}{mu}{sup -}) = (2.23 {+-} 0.25{sub stat} {+-} 0.27{sub sys}) x 10{sup -6} and {Beta}({Upsilon}(4S) {yields} {pi}{sup +}{pi}{sup -}{Upsilon}(2S)) x {Beta}({Upsilon}(2S) {yields} {mu}{sup +}{mu}{sup -}) = (1.69 {+-} 0.26{sub stat} {+-} 0.20{sub sys}) x 10{sup -6}, from which they derive the partial widths {Lambda}({Upsilon}(4S) {yields} {pi}{sup +}{pi}{sup -} {Upsilon}(1S)) = (1.8 {+-} 0.4) keV and {Lambda}({Upsilon}(4S) {yields} {pi}{sup +}{pi}{sup -}{Upsilon}(2S)) = (2.7 {+-} 0.8) keV.
Date: April 19, 2006
Creator: Aubert, B.
Partner: UNT Libraries Government Documents Department