Controlling ρ width effects for a precise value of α in B→ρρ
It has been pointed out that the currently most precise determination of the weak phase ϕ2=α of the Cabibbo–Kobayashi–Maskawa (CKM) matrix achieved in B→ρρ decays is susceptible to a small correction at a level of (Γρ/mρ)2 due to an I=1 amplitude caused by the ρ width. Using Breit–Wigner distributio...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2017-03-01
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| Series: | Physics Letters B |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0370269317300291 |
| Summary: | It has been pointed out that the currently most precise determination of the weak phase ϕ2=α of the Cabibbo–Kobayashi–Maskawa (CKM) matrix achieved in B→ρρ decays is susceptible to a small correction at a level of (Γρ/mρ)2 due to an I=1 amplitude caused by the ρ width. Using Breit–Wigner distributions for the two pairs of pions forming ρ mesons, we study the I=1 contribution to B→ρρ decay rates as function of the width and location of the ρ band. We find that in the absence of a particular enhancement of the I=1 amplitude reducing a single band to a width Γρ at SuperKEKB leads to results which are completely insensitive to the ρ width. If the I=1 amplitude is dynamically enhanced relative to the I=0,2 amplitude one could subject its contribution to a “magnifying glass” measurement using two separated ρ bands of width Γρ. Subtraction of the I=1 contribution from the measured decay rate would lead to a very precise determination of the I=0,2 amplitude needed for performing the isospin analysis. |
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| ISSN: | 0370-2693 1873-2445 |