Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Controlling $\rho$ width effects for a precise value of $\alpha$ in $B
  \to \rho \rho$   It has been pointed out that the currently most precise determination of the
weak phase $\phi_2 = \alpha$ of the Cabibbo-Kobayashi-Maskawa (CKM) matrix
achieved in $B \to \rho\rho$ decays is susceptible to a small correction at a
level of $(\Gamma_\rho/m_\rho)^2$ due to an $I=1$ amplitude caused by the
$\rho$ width. Using Breit-Wigner distributions for the two pairs of pions
forming $\rho$ mesons, we study the $I=1$ contribution to $B\to \rho\rho$ decay
rates as function of the width and location of the $\rho$ band. We find that in
the absence of a particular enhancement of the $I=1$ amplitude reducing a
single band to a width $\Gamma_\rho$ at SuperKEKB leads to results which are
completely insensitive to the $\rho$ 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 $\rho$
bands of width $\Gamma_\rho$. 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.

34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
23
The categories of this paper are: solv-int
6
The categories of this paper are: astro-ph