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Precise measurement of the $K^{\pm} \to \pi^{\pm}e^{+}e^{−}$ decay (2009) |
- Batley, J R,
- Culling, A J,
- Kalmus, G,
- Lazzeroni, C,
- Munday, D J,
- Slater, M W,
- Wotton, S A,
- Arcidiacono, R,
- Bocquet, G,
- Cabibbo, N,
- Ceccucci, A,
- Cundy, D,
- Falaleev, V,
- Fidecaro, M,
- Gatignon, L,
- Gonidec, A,
- Kubischta, W,
- Norton, A,
- Maier, A,
- Patel, M,
- Peters, A,
- Balev, S,
- Frabetti, P L,
- Goudzovski, E,
- Khristov, P Z,
- Kekelidze, V,
- Kozhuharov, V,
- Litov, L,
- Madigozhin, D T,
- Marinova, E,
- Molokanova, N,
- Polenkevich, I,
- Potrebenikov, Yu,
- Stoynev, S,
- Zinchenko, A,
- Monnier, E,
- Swallow, E,
- Winston, R,
- Rubin, P,
- Walker, A,
- Baldini, W,
- Cotta-Ramusino, A,
- Dalpiaz, P,
- Damiani, C,
- Fiorini, M,
- Gianoli, A,
- Martini, M,
- Petrucci, F,
- Savrié, M,
- Scarpa, M,
- Wahl, H,
- Bizzeti, A,
- Calvetti, M,
- Celeghini, E,
- Iacopini, E,
- Lenti, M,
- Martelli, F,
- Ruggiero, G,
- Veltri, M,
- Behler, M,
- Eppard, K,
- Kleinknecht, K,
- Marouelli, P,
- Masetti, L,
- Moosbrugger, U,
- Morales-Morales, C,
- Renk, B,
- Wache, M,
- Wanke, R,
- Winhart, A,
- Coward, D,
- Dabrowski, A,
- Fonseca-Martin, T,
- Shieh, M,
- Szleper, M,
- Velasco, M,
- Wood, M D,
- Anzivino, G,
- Cenci, P,
- Imbergamo, E,
- Nappi, A,
- Pepé, M,
- Petrucci, M C,
- Piccini, M,
- Raggi, M,
- Valdata-Nappi, M,
- Cerri, C,
- Fantechi, R,
- Collazuol, G,
- Di Lella, L,
- Lamanna, G,
- Mannelli, I,
- Michetti, A,
- Costantini, F,
- Doble, N,
- Fiorini, L,
- Giudici, S,
- Pierazzini, G,
- Sozzi, M,
- Venditti, S,
- Bloch-Devaux, B,
- Cheshkov, C,
- Chèze, J B,
- De Beer, M,
- Derré, J,
- Marel, G,
- Mazzucato, E,
- Peyaud, B,
- Vallage, B,
- Holder, M,
- Ziolkowski, M,
- Bifani, S,
- Biino, C,
- Cartiglia, N,
- Clemencic, M,
- Goy-Lopez, S,
- Marchetto, F,
- Dibon, H,
- Jeitler, M,
- Markytan, M,
- Mikulec, I,
- Neuhofer, G,
- Widhalm, L
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Abstract |
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A sample of 7253 $K^\pm\to\pi^\pm e^+e^-(\gamma)$ decay candidates with 1.0% background contamination has been collected by the NA48/2 experiment at the CERN SPS, allowing a precise measurement of the decay properties. The branching ratio in the full kinematic range was measured to be ${\rm BR}=(3.11\pm0.12)\times 10^{-7}$, where the uncertainty includes also the model dependence. The shape of the form factor $W(z)$, where $z=(M_{ee}/M_K)^2$, was parameterized according to several models, and, in particular, the slope $\delta$ of the linear form factor $W(z)=W_0(1+\delta z)$ was determined to be $\delta=2.32\pm0.18$. A possible CP violating asymmetry of $K^+$ and $K^-$ decay widths was investigated, and a conservative upper limit of $2.1\times 10^{-2}$ at 90% CL was established. |
Publication details |
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