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Xi0 and anti-Xi0 Polarization Measurements at 800-GeV/c

Description: The polarization of {Xi}{sup 0} and {bar {Xi}}{sup 0} 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. The result of 9.7% for {Xi}{sup 0} polarization shows no significant energy dependence when compared to a result obtained at 400 GeV/c production energy and at twice the targeting angle. The polarization of the {Xi}{sup 0} is measured for the first time and found to be consistent with zero. They also examine the dependence of polarization on production p{sub t}.
Date: August 1, 2006
Creator: Abouzaid, E.; Alavi-Harati, A.; Alexopoulos, T.; Arenton, M.; Barker, A. R.; Bellantoni, L. et al.
Partner: UNT Libraries Government Documents Department

Measurement of direct photon emission in the K(L) ---> pi+ pi- gamma decay mode

Description: In this paper the KTeV collaboration reports the analysis of 112.1 x 10{sup 3} candidate K{sub L} {yields} {pi}{sup +}{pi}{sup -}{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 |{bar g}{sub M1}|(1 + a{sub 1}/a{sub 2}/(M{sub {rho}}{sup 2}-M{sub K}{sup 2}) + 2M{sub K}E{sub {gamma}}) have been measured to be |{bar g}{sub M1}| = 1.198 {+-} 0.035(stat) {+-} 0.086(syst) and a{sub 1}/a{sub 2} = =0.738 {+-} 0.007(stat) {+-} 0.018(syst) GeV{sup 2}/c{sup 2} respectively. An upper limit for the CP violating E1 direct emission amplitude |g{sub E1}| {le} 0.1 (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{sub {gamma}} {ge} 20 MeV.
Date: April 1, 2006
Creator: Abouzaid, E.; /Chicago U., EFI; Arenton, M.; U., /Virginia; Barker, A.R.; U., /Colorado et al.
Partner: UNT Libraries Government Documents Department

Observation of the decay Xi0 ---> Sigma+ mu- anti-nu(mu)

Description: The {Xi}{sup 0} muon semi-leptonic 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 {Lambda}({Xi}{sup 0} {yields} {Sigma}{sup +}{mu}{sup -}{bar {nu}}{sub {mu}})/{Lambda}({Xi}{sup 0} {yields} {Sigma}{sup +}e{sup -} {bar {nu}}{sub e}) of (1.8{sub -0.5}{sup +0.7}(stat.) {+-} 0.2(syst.)) x 10{sup -2} at the 68% confidence level. This is in agreement with the SU(3) flavor symmetric quark model.
Date: April 1, 2005
Creator: Alavi-Harati, A.; Alexopoulos, T.; Arenton, M.; Barbosa, R. F.; Barker, A. R.; Barrio, M. et al.
Partner: UNT Libraries Government Documents Department

A Measurement of the K0 charge radius and a CP violating asymmetry together with a search for CP violating e1 direct photon emission in the rare decay K(L) ---> pi+ pi- e+ e-

Description: Using the complete KTeV data set of 5241 candidate K{sub L} {yields} {pi}{sup +}{pi}{sup -}e{sup +}e{sup -} decays (including an estimated background of 204 {+-} 14 events), we have measured the coupling g{sub CR} = 0.163 {+-} 0.014 (stat) {+-} 0.023 (syst) of the CP conserving charge radius process and from it determined a K{sup 0} charge radius of <r{sub K{sup 0}}{sup 2}> = (-0.077 {+-} 0.007(stat) {+-} 0.011(syst))fm{sup 2}. We have also determined a first experimental upper limit of 0.04 (90% CL) for the ratio |g{sub E1}|/|g{sub M1}| of the coupling for the E1 direct photon emission process relative to the coupling for M1 direct photon emission process. We also report the measurement of |g{sub M1}| including its associated vector form factor |{bar g}{sub M1}|1 + a{sub 1}/a{sub 2}/(M{sub p}{sup 2} - M{sub K}{sup 2})+2M{sub K}E{sub {gamma}*} where |{bar g}{sub M1}| = 1.11 {+-} 0.12 (stat) {+-} 0.08 (syst) and a{sub 1}/a{sub 2} = (-0.744 {+-} 0.027 (stat) {+-} 0.032 (syst)) GeV{sup 2}/c{sup 2}. In addition, a measurement of the manifestly CP violating asymmetry of magnitude (13.6 {+-} 1.4 (stat) {+-} 1.5 (syst))% in the CP and T odd angle {phi} between the decay planes of the e{sup +}e{sup -} and {pi}{sup +}{pi}{sup -} pairs in the K center of mass system is reported.
Date: August 1, 2005
Creator: Abouzaid, E.; Arenton, M.; Barker, A. R.; Bellantoni, L.; Bellavance, A.; Blucher, E. et al.
Partner: UNT Libraries Government Documents Department