Evidence for the Flavor Changing Neutral Current Decays B-]Kll and B-]K*ll
Evidence for the Flavor Changing Neutral Current Decays B-]Kll and B-]K*ll

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Published: 2003

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The authors present preliminary results from a search for the rare, flavor-changing neutral current decays B[yields] K[ell][sup+][ell][sup -] and B[yields] K*[ell][sup+][ell][sup -], where[ell][sup+][ell][sup -] is either an e[sup+]e[sup -] or[mu][sup+][mu][sup -] pair. The data sample comprises (84.4[+-] 0.9) x 10[sup 6][Upsilon](4S)[yields] B[bar B] decays (77.8 fb[sup -1]) collected with the BaBar detector at the PEP-II B Factory. For B[yields] K[ell][sup+][ell][sup -], they observe a signal with estimated significance of 4.4[sigma] and obtain[Beta](B[yields] K[ell][sup+][ell][sup -])= (0.78[sub -0.20-0.18][sup+0.24+0.11]) x 10[sup 06] (averaged over[ell]= e and[mu]). For B[yields] K*[ell][sup+][ell][sup -], they observe an excess of events over background with estimated significance of 2.8[sigma]. They obtain[Beta](B[yields] K*[ell][sup+][ell][sup -])= (1.68[sub -0.58][sup+0.68][+-] 0.28) x 10[sup -6] and the 90% C.L. upper limit[Beta](B[yields] K*[ell][sup+][ell][sup -])

Search for B 2!Kll− and B 2!K*(892)l+l−
Search for B 2!Kll− and B 2!K*(892)l+l−

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Published: 2004

Total Pages: 21

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The authors present preliminary results from a search for the flavor-changing neutral current decays B → Kll− and B → K*(892)l+l− using a sample of 22.7 x 106?(4S) → B{bar B} decays collected with the BABAR detector at the PEP-II B Factory. They have reconstructed the following final states: B+ → K+l+l−, B° → K°l+l− (K{sub s}° →?+?−), B+ → K*+l+l− (K*+ → K{sub s}°?+), and B° → K*°l+l− (K*° → K+?−), where l+l− is either an e+e− or?+?− pair. They obtain the 90% C.L. upper limits?(B → Kl+l−)

Flavor Changing Neutral Current B Decays at BaBar
Flavor Changing Neutral Current B Decays at BaBar

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Published: 2004

Total Pages: 5

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Recent BaBar results on rare B decays involving flavour-changing neutral currents are presented. New measurements of the CP asymmetries in b 2!s[gamma] decays are reported as well as b 2!sll− branching ratio measurements.

Search for Flavor Changing Neutral Currents K
Search for Flavor Changing Neutral Currents K

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Published: 1988

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We report on a search for the flavor-changing neutral-current decays K/sub L/ e e, K/sub L/ e e and K/sub L/ /sup +-/e/sup /minus plus//. Limits obtained for these processes are BR(K/sub L/ e e)

Observation of the Baryonic Flavor-Changing Neutral Current Decay $\Lambda_b0̂ \to \Lambda \mu+̂ \mu-̂$
Observation of the Baryonic Flavor-Changing Neutral Current Decay $\Lambda_b0̂ \to \Lambda \mu+̂ \mu-̂$

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Published: 2011

Total Pages: 7

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The authors report the first observation of the baryonic flavor-changing neutral current decay?{sub b}° →???− with 24 signal events and a statistical significance of 5.8 Gaussian standard deviations. This measurement uses a p{bar p} collisions data sample corresponding to 6.8 fb−1 at √s = 1.96 TeV collected by the CDF II detector at the Tevatron collider. The total and differential branching ratios for?{sub b}° →??+?− are measured. They find?(?{sub b}° →??+?−) = [1.73 ± 0.42(stat) ± 0.55(syst)] x 10−6. They also report the first measurement of the differential branching ratio of B{sub s}° →??+?− using 49 signal events. In addition, they report branching ratios for B+ → K+?+?−, B° → K°?+?− and B → K*(892)?+?− decays.

Observation of the Baryonic Flavor-Changing Neutral Current Decay [Lambda]b0 → [Lambda]μ+μ-.
Observation of the Baryonic Flavor-Changing Neutral Current Decay [Lambda]b0 → [Lambda]μ+μ-.

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Published: 2011

Total Pages: 8

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The authors report the first observation of the baryonic flavor-changing neutral current decay [Lambda]b0 → [Lambda]μ+μ- with 24 signal events and a statistical significance of 5.8 Gaussian standard deviations. This measurement uses a pp̄ collisions data sample corresponding to 6.8 fb-1 at √s = 1.96 TeV collected by the CDF II detector at the Tevatron collider. The total and differential branching ratios for [Lambda]b0 → [Lambda]μ+μ- are measured. They find [Beta]([Lambda]b0 → [Lambda]μ+μ-) = [1.73 ± 0.42(stat) ± 0.55(syst)] x 10-6. They also report the first measurement of the differential branching ratio of Bs0→[phi]μ+μ- using 49 signal events. In addition, they report branching ratios for B+→K+μ+μ-, B0→K0μ+μ- and [Beta]→ K*(892)μ+μ- decays.

Evidence for K ---] K* L+ L- and Measurement of B ---] K L+ L-
Evidence for K ---] K* L+ L- and Measurement of B ---] K L+ L-

Author: A. Ryd

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Published: 2005

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The authors present evidence for the flavor-changing neutral current decay B {yields} K*{ell}{sup +}{ell}{sup -} and a measurement of the B {yields} K{ell}{sup +}{ell}{sup -} branching fraction, where {ell}{sup +}{ell}{sup -} is either an e{sup +}e{sup -} or {mu}{sup +}{mu}{sup -} pair. The data sample analyzed comprises 88.5 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II e{sup +}e{sup -} storage ring. Averaging over K{sup (*)} isospin and lepton flavor, we obtain {Beta}(B {yields} K*{ell}{sup +}{ell}{sup -}) = (1.40{sub -0.49}{sup +0.57} {+-} 0.21) x 10{sup -6} and {Beta}(B {yields} K{ell}{sup +}{ell}{sup -}) = (0.68{sub -0.15}{sup +0.17} {+-} 0.04) x 10{sup -6}, where the uncertainties are statistical and systematic. The significance for the B {yields} K*{ell}{sup +}{ell}{sup -} signal is 3.0{sigma} and for B {yields} K{ell}{sup +}{ell}{sup -} the signal significance is over 7{sigma}.