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...

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Main Authors: Michael Gronau, Jonathan L. Rosner
Format: Article
Language:English
Published: Elsevier 2017-03-01
Series:Physics Letters B
Online Access:http://www.sciencedirect.com/science/article/pii/S0370269317300291
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spelling doaj-4f0c962ab98147caad4b40fad713d34e2020-11-24T22:54:36ZengElsevierPhysics Letters B0370-26931873-24452017-03-01766C34535010.1016/j.physletb.2017.01.022Controlling ρ width effects for a precise value of α in B→ρρMichael Gronau0Jonathan L. Rosner1Physics Department, Technion, Haifa 32000, IsraelEnrico Fermi Institute and Department of Physics, University of Chicago, Chicago, IL 60637, USAIt 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.http://www.sciencedirect.com/science/article/pii/S0370269317300291
collection DOAJ
language English
format Article
sources DOAJ
author Michael Gronau
Jonathan L. Rosner
spellingShingle Michael Gronau
Jonathan L. Rosner
Controlling ρ width effects for a precise value of α in B→ρρ
Physics Letters B
author_facet Michael Gronau
Jonathan L. Rosner
author_sort Michael Gronau
title Controlling ρ width effects for a precise value of α in B→ρρ
title_short Controlling ρ width effects for a precise value of α in B→ρρ
title_full Controlling ρ width effects for a precise value of α in B→ρρ
title_fullStr Controlling ρ width effects for a precise value of α in B→ρρ
title_full_unstemmed Controlling ρ width effects for a precise value of α in B→ρρ
title_sort controlling ρ width effects for a precise value of α in b→ρρ
publisher Elsevier
series Physics Letters B
issn 0370-2693
1873-2445
publishDate 2017-03-01
description 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.
url http://www.sciencedirect.com/science/article/pii/S0370269317300291
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