-
T. S. Nigmanov,
D. Rajaram,
M. J. Longo,
U. Akgun,
G. Aydin,
W. Baker,
Barnes, Jr., P. D,
T. Bergfeld,
A. Bujak,
D. Carey, [......],
C. Rosenfeld,
H. A. Rubin,
S. Seun,
N. Solomey,
R. Soltz,
E. Swallow,
Y. Torun,
K. Wilson,
D. Wright,
K. Wu
[show abstract]
[hide abstract]
ABSTRACT: We have measured cross sections for forward neutron production from a variety
of targets using proton beams from the Fermilab Main Injector. Measurements
were performed for proton beam momenta of 58 GeV/c, 84 GeV/c, and 120 GeV/c.
The cross section dependence on the atomic weight (A) of the targets was found
to vary as $A^(alpha)$ where $\alpha$ is $0.46\pm0.06$ for a beam momentum of
58 GeV/c and 0.54$\pm$0.05 for 120 GeV/c. The cross sections show reasonable
agreement with FLUKA and DPMJET Monte Carlos. Comparisons have also been made
with the LAQGSM Monte Carlo.
10/2010;
-
HyperCP Collaboration,
O. Kamaev,
N Solomey,
R. A. Burnstein,
A. Chakravorty,
Y C Chen,
W. S. Choong,
K Clark,
E. C. Dukes,
C. Durandet, [......],
K. B. Luk, K S Nelson,
H K Park,
J. -P. Perroud,
D. Rajaram,
H A Rubin,
J. Volk,
C. G. White,
S L White,
P. Zyla
[show abstract]
[hide abstract]
ABSTRACT: We report a new measurement of the decay \Omega^- \to \Xi^- \pi^+ \pi^- with 76 events and a first observation of the decay \Omega^+ \to \Xi^+ \pi^+ \pi^- with 24 events, yielding a combined branching ratio (3.74 ^{+0.67}_{-0.56}) \times 10^{-4}. This represents a factor 25 increase in statistics over the best previous measurement. No evidence is seen for CP violation, with B(\Omega^- \to \Xi^- \pi^+ \pi^-)=4.04^{+0.83}_{-0.71} \times 10^{-4} and B(\Omega^+ \to \Xi^+ \pi^+ \pi^-)=3.15^{+1.12}_{-0.89} \times 10^{-4}. Contrary to theoretical expectation, we see little evidence for the decays \Omega^- \to \Xi_{1530}^{*0} \pi^- and \Omega^+ \to \Xi_{1530}^{*0} \pi^+ and place a 90% C.L. upper limit on the combined branching ratio B(\Omega^-(\Omega^+) \to \Xi^{*0}_{1530}(\Xi^{*0}_{1530}) \pi^\mp)<7.0 \times 10^{-5}. Comment: 6 pages, 5 figures, to be published in Phys. Lett. B
08/2010;
-
T. Alexopoulos,
E.W. Anderson,
D. D. Carmony,
A R Erwin,
C. Findeisen,
K. Gulbrandsen,
L J Gutay,
A. S. Hirsch,
C. Hojvat,
J. R. Jennings,
C. Loomis,
J. M LoSecco, K S Nelson,
S H Oh,
N. T. Porile,
R. P. Scharenberg,
F. Turkot,
W D Walker,
C H Wang,
J Warchol
[show abstract]
[hide abstract]
ABSTRACT: A set of inclusive cross sections at zero rapidity is presented for p-pbar interactions at center of mass energy sqrt(s)=1.8 TeV. Six particle cross sections are corrected for secondary contributions from decays of higher mass resonances in order to produce a set of primary cross sections. The primary cross sections per spin state are well described by d(sigma^p)/dy|_(y=0)= 0.721*(pi*lambdabar_(pi)^2)*exp(-m/T), where m is the particle rest mass, T=hbar*c/r_h, and r_h=0.97 fm. The deuterium production cross section is also described if r_h is replaced by r_A=r_h*A^(1/3). The same exponential in m and T describes primary charm fractions in e+e- collisions at least up to the J/Psi mass. There is no significant evidence for strangeness or charm suppression if only primary production of light hadrons is considered. There is evidence that the primary cross section for each particle may have the same value for pp and pbar-p collisions and that it may have nearly constant values between sqrt(s)=63 GeV and sqrt(s)=1800 GeV. Fits to the final state transverse momenta of the particles using a gas model favor a temperature T=132 MeV, a chemical potential mu=129 MeV, and a transverse flow of the gas with beta_f=0.27. Comment: 20 pages, 18 figures
09/2009;
-
E. Abouzaid,
M. Arenton,
A. R. Barker,
L. Bellantoni,
E. Blucher,
G. J. Bock,
E. Cheu,
R. Coleman,
B. Cox,
A. R. Erwin, [......],
J. Wang,
H. B. White,
J. Whitmore,
M. J. Wilking,
R. Winston,
E. T. Worcester,
M. Worcester,
T. Yamanaka,
E. D. Zimmerman,
R. F. Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: We report on a new measurement of the branching ratio B(KL→π0e+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→π0e+e-γ)=(1.62±0.14stat±0.09syst)×10-8. This result supersedes the earlier KTeV measurement of this branching ratio.
Phys. Rev. D. 09/2007; 76(5).
-
E Abouzaid,
M Arenton,
A R Barker,
L Bellantoni,
E Blucher,
G J Bock,
E Cheu,
R Coleman,
M D Corcoran,
B Cox, [......],
H B White,
J Whitmore,
M J Wilking,
B Winstein,
R Winston,
E T Worcester,
M Worcester,
T Yamanaka,
E D Zimmerman,
R F Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: 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.
Physical Review Letters 08/2007; 99(8):081803. · 7.37 Impact Factor
-
KTeV Collaboration: E. Abouzaid,
M. Arenton,
A R Barker,
L Bellantoni,
E Blucher,
G J Bock,
E Cheu,
R Coleman,
B Cox,
A R Erwin, [......],
J Wang,
H B White,
J Whitmore,
M. J. Wilking,
R Winston,
E T Worcester,
M Worcester,
T Yamanaka,
E. D. Zimmerman,
R F Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: We report on a new measurement of the branching ratio B(KL -> pi0 e+ e- gamma) 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 -> pi0 e+ e- gamma) = (1.62 +/- 0.14 (stat) +/- 0.09 (syst)) x 10^{-8}. This result supersedes the earlier KTeV measurement of this branching ratio.
07/2007;
-
E. Abouzaid,
M. Arenton,
A. R. Barker,
L. Bellantoni,
A. Bellavance,
E. Blucher,
G. J. Bock,
E. Cheu,
R. Coleman,
M. D. Corcoran, [......],
H. B. White,
J. Whitmore,
M. J. Wilking,
B. Winstein,
R. Winston,
E. T. Worcester,
M. Worcester,
T. Yamanaka,
E. D. Zimmerman,
R. F. Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: 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.
Phys. Rev. D. 01/2007; 75(1).
-
E. Abouzaid,
A. Alavi-Harati,
T. Alexopoulos,
M. Arenton,
A. R. Barker,
L. Bellantoni,
A. Bellavance,
E. Blucher,
G. J. Bock,
S. Bright, [......],
H. B. White,
J. Whitmore,
M. Wilking,
B. Winstein,
R. Winston,
E. T. Worcester,
M. Worcester,
T. Yamanaka,
E. D. Zimmerman,
R. F. Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: The polarization of Ξ0 and Ξ̅ 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. Our result of 9.7% for Ξ0 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 Ξ̅ 0 is measured for the first time and found to be consistent with zero. We also examine the dependence of polarization on production pt.
Phys. Rev. D. 01/2007; 75(1).
-
E. Abouzaid,
M. Arenton,
A. R. Barker,
L. Bellantoni,
A. Bellavance,
E. Blucher,
G. J. Bock,
E. Cheu,
R. Coleman,
M. D. Corcoran, [......],
H. B. White,
J. Whitmore,
M. Wilking,
B. Winstein,
R. Winston,
E. T. Worcester,
M. Worcester,
T. Yamanaka,
E. D. Zimmerman,
R. F. Zukanovich
Physical review D: Particles and fields 07/2006; 74(3):39905.
-
L C Lu,
R A Burnstein,
A Chakravorty,
Y C Chen,
W-S Choong,
K Clark,
E C Dukes,
C Durandet,
J Felix,
Y Fu, [......],
K-B Luk, K S Nelson,
H K Park,
J-P Perroud,
D Rajaram,
H A Rubin,
J Volk,
C G White,
S L White,
P Zyla
[show abstract]
[hide abstract]
ABSTRACT: The asymmetry in the rho angular distribution in the sequential decay Omega+-->LamdaKappa+-->rhopi+Kappa+. has been measured to be alphaOmegaalphaLamda=[+1.16+/-0.18(stat)+/-0.17(syst)]x10(-2) using 1.89x10(6) unpolarized Omega+ decays recorded by the HyperCP (E871) experiment at Fermilab. Using the known value of alphaLamda, and assuming that alphaLamda=-alphaLamda, alphaOmega=[-1.81+/-0.28(stat)+/-0.26(syst)]x10(-2). A comparison between this measurement of alphaOmegaalphaLamda and recent measurements of alphaOmegaalphaLamda made by HyperCP shows no evidence of a violation of CP symmetry.
Physical Review Letters 07/2006; 96(24):242001. · 7.37 Impact Factor
-
L. C. Lu,
R. A. Burnstein,
A. Chakravorty,
Y. C. Chen,
W.-S. Choong,
K. Clark,
E. C. Dukes,
C. Durandet,
J. Felix,
Y. Fu, [......],
K.-B. Luk, K. S. Nelson,
H. K. Park,
J.-P. Perroud,
D. Rajaram,
H. A. Rubin,
J. Volk,
C. G. White,
S. L. White,
P. Zyla
[show abstract]
[hide abstract]
ABSTRACT: The asymmetry in the p¯ angular distribution in the sequential
decay
Ω¯+→Λ¯K+→p¯π+K+
has been measured to be
α¯Ωα¯Λ=[+1.16±0.18(stat)±0.17(syst)]×10-2
using 1.89×106 unpolarized Ω¯+
decays recorded by the HyperCP (E871) experiment at Fermilab. Using the
known value of αΛ, and assuming that
α¯Λ=-αΛ,
α¯Ω=[-1.81±0.28(stat)±0.26(syst)]×10-2.
A comparison between this measurement of
α¯Ωα¯Λ and
recent measurements of
αΩαΛ made by HyperCP
shows no evidence of a violation of CP symmetry.
Physical Review Letters 05/2006; 96(24):242001. · 7.37 Impact Factor
-
E Abouzaid,
M Arenton,
A R Barker,
L Bellantoni,
A Bellavance,
E Blucher,
G J Bock,
E Cheu,
R Coleman,
M D Corcoran, [......],
H B White,
J Whitmore,
M Wilking,
B Winstein,
R Winston,
E T Worchester,
M Worchester,
T Yamanaka,
E D Zimmerman,
R F Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: Using the complete KTeV data set of 5,241 candidate K(L)--> pi(+) pi(-) e(+) e(-) decays (including an estimated background of 204 +/- 14 events), we have measured the coupling g(CR)= 0.163 +/- 0.0149(stat) +/- 0.023(syst) of the CP conserving charge radius process and from it determined a K(0) charge radius of <r(2)(K(0))> = [-0.077 +/- 0.007(stat) +/- 0.011(syst)]fm(2). We have determined a first experimental upper limit of 0.04 (90% C.L.) /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 /g(M1)/(1 + (a(1)/a(2))/((M(2)(p)-(M(2)(k))= 2M(K)E(gamma*)), where vector /g(M1)/= 1.11+/- 0.12(stat) +/- 0.08(syst) and a(1)/a(2) = [-0.744 +/- 0.027(stat) +/- 0.032(syst)] GeV(2)/c(2). Finally, a CP-violating asymmetry of [13.6 +/- 1.4(stat) +/- 1.5(syst)]% in the CP and T odd angle phi between the decay planes of the e(+) e(-) and pi(+) pi(-) pairs in the K(L) center of mass is reported.
Physical Review Letters 03/2006; 96(10):101801. · 7.37 Impact Factor
-
E Abouzaid,
T Alexopoulos,
M Arenton,
R F Barbosa,
A R Barker,
L Bellantoni,
A Bellavance,
E Blucher,
G J Bock,
E Cheu, [......],
H B White,
J Whitmore,
M Wilking,
B Winstein,
R Winston,
E T Worcester,
M Worcester,
T Yamanaka,
E D Zimmerman,
R F Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: 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.
Physical Review Letters 09/2005; 95(8):081801. · 7.37 Impact Factor
-
HyperCP Collaboration: D. Rajaram,
R. A. Burnstein,
A. Chakravorty,
Y C Chen,
W. S. Choong,
K Clark,
E. C. Dukes,
C. Durandet,
J. Felix,
Y Fu, [......],
W. Luebke,
K. B. Luk, K S Nelson,
H K Park,
J. -P. Perroud,
H A Rubin,
J. Volk,
C. G. White,
S L White,
P. Zyla
[show abstract]
[hide abstract]
ABSTRACT: A sensitive search for the lepton-number-violating decay $\Xi^-\to p \mu^-\mu^-$ has been performed using a sample of $\sim10^9$ $\Xi^-$ hyperons produced in 800 GeV/$c$ $p$-Cu collisions. We obtain $\mathcal{B}(\Xi^-\to p \mu^-\mu^-)< 4.0\times 10^{-8}$ at 90% confidence, improving on the best previous limit by four orders of magnitude.
06/2005;
-
HyperCP Collaboration: L. C. Lu,
R. A. Burnstein,
A. Chakravorty,
Y C Chen,
W. S. Choong,
K Clark,
E. C. Dukes,
C. Durandet,
J. Felix,
Y Fu, [......],
K. B. Luk, K S Nelson,
H K Park,
J. -P. Perroud,
D. Rajaram,
H A Rubin,
J. Volk,
C. G. White,
S L White,
P. Zyla
[show abstract]
[hide abstract]
ABSTRACT: The alpha decay parameter in the process Omega-minus -> Lambda + K-minus has been measured from a sample of 4.50 million unpolarized Omega-minus decays recorded by the HyperCP (E871) experiment at Fermilab and found to be [1.78 +/- 0.19(stat) +/- 0.16(syst)]{\times}10^{-2}. This is the first unambiguous evidence for a nonzero alpha decay parameter, and hence parity violation, in the Omega-minus -> Lambda + K-minus decay.
06/2005;
-
KTeV Collaboration: E. Abouzaid,
T. Alexopoulos,
M. Arenton,
R F Barbosa,
A R Barker,
L Bellantoni,
A Bellavance,
E Blucher,
G J Bock,
E Cheu, [......],
H B White,
J Whitmore,
M Wilking,
B Winstein,
R Winston,
E T Worcester,
M Worcester,
T Yamanaka,
E. D. Zimmerman,
R F Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: The Xi^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^0 beta decay mode and yields a value for the ratio of decay rates of $(1.8^{+0.7}_{-0.5}(stat.)\pm0.2(syst.))\times 10^{-2}$. This is in agreement with the SU(3) flavor symmetric quark model.
05/2005;
-
D Rajaram,
R A Burnstein,
A Chakravorty,
A Chan,
Y C Chen,
W S Choong,
K Clark,
E C Dukes,
C Durandet,
J Felix, [......],
K B Luk, K S Nelson,
H K Park,
J-P Perroud,
H A Rubin,
P K Teng,
J Volk,
C G White,
S L White,
P Zyla
[show abstract]
[hide abstract]
ABSTRACT: A sensitive search for the lepton-number-violating decay Xi(-)-->pmu(-)mu(-) has been performed using a sample of approximately 10(9) Xi(-) hyperons produced in 800 GeV/c p-Cu collisions. We obtain B(Xi(-)-->pmu(-)mu(-))<4.0x10(-8) at 90% confidence, improving on the best previous limit by 4 orders of magnitude.
Physical Review Letters 05/2005; 94(18):181801. · 7.37 Impact Factor
-
C. G. White,
R. A. Burnstein,
A. Chakravorty,
A Chan,
Y C Chen,
W. S. Choong,
K Clark,
E. C. Dukes,
C. Durandet,
J. Felix, [......],
K. B. Luk, K S Nelson,
H K Park,
J. -P. Perroud,
D. Rajaram,
H A Rubin,
P. K. Teng,
J. Volk,
S L White,
P. Zyla
[show abstract]
[hide abstract]
ABSTRACT: A sensitive search for the rare decays \Omega^- \to \Lambda \pi^- and \Xi^0 \to p \pi^- has been performed using data from the 1997 run of the HyperCP (Fermilab E871) experiment. Limits on other such processes do not exclude the possibility of observable rates for |\Delta S| = 2 nonleptonic hyperon decays, provided the decays occur through parity-odd operators. We obtain the branching-fraction limits B(\Omega^- \to \Lambda \pi^-)< 2.9 x 10^{-6} and B(\Xi^0 \to p \pi^-)< 8.2 x 10^{-6}, both at 90% confidence level.
04/2005;
-
HyperCP Collaboration: Y. C. Chen,
R. A. Burnstein,
A. Chakravorty,
A Chan,
W. S. Choong,
K Clark,
E. C. Dukes,
C. Durandet,
J. Felix,
G. Gidal, [......], K S Nelson,
H K Park,
J. -P. Perroud,
D. Rajaram,
H A Rubin,
P. K. Teng,
J. Volk,
C. G. White,
S L White,
P. Zyla
[show abstract]
[hide abstract]
ABSTRACT: We have measured the alpha parameter of the Omega- to Lambda K- decay using data collected with the HyperCP spectrometer during the 1997 fixed-target run at Fermilab. Analyzing a sample of 0.96 million Omega- to Lambda K^-, Lambda to p pi- decays, we obtain alpha_Omega*alpha_Lambda = [1.33+/-0.33(stat)+/-0.52(syst)] x 10^{-2}. With the accepted value of alpha_Lambda, alpha_Omega is found to be [2.07+/-0.51(stat)+/-0.81(syst)] x 10^{-2}.
03/2005;
-
C G White,
R A Burnstein,
A Chakravorty,
A Chan,
Y C Chen,
W S Choong,
K Clark,
E C Dukes,
C Durandet,
J Felix, [......],
K B Luk, K S Nelson,
H K Park,
J-P Perroud,
D Rajaram,
H A Rubin,
P K Teng,
J Volk,
S L White,
P Zyla
[show abstract]
[hide abstract]
ABSTRACT: A sensitive search for the rare decays Omega(-)--> Lambdapi(-) and Xi(0)--> ppi(-) has been performed using data from the 1997 run of the HyperCP (Fermilab E871) experiment. Limits on other such processes do not exclude the possibility of observable rates for |DeltaS| = 2 nonleptonic hyperon decays, provided the decays occur through parity-odd operators. We obtain the branching-fraction limits B(Omega(-)-->Lambdapi(-)) < 2.9 x 10(-6) and B(Xi(0)--> ppi(-)) < 8.2 x 10(-6), both at 90% confidence level.
Physical Review Letters 03/2005; 94(10):101804. · 7.37 Impact Factor
