# Tests of the standard model in $B\to D\ell {\nu}_{\ell}$ , $B\to {D}^{*}\ell {\nu}_{\ell}$ and ${B}_{c}\to J/\psi \ell {\nu}_{\ell}$

## Abstract

A number of recent experimental measurements suggest the possibility of a breakdown of lepton (ℓ) universality in exclusive b → cℓν _{ℓ} semileptonic meson decays. We analyze the full differential decay rates for several such processes, and show how to extract combinations of the underlying helicity amplitudes that are completely independent of m ℓ. Ratios of these combinations for different ℓ (as well as some combinations for a single value of ℓ) therefore equal unity in the standard model and provide stringent tests of lepton universality. Furthermore, the extractions assume the form of weighted integrals over the differential decay rates and therefore are useful even in situations where data in some regions of allowed phase space may be sparse.

- Authors:

- Publication Date:

- Research Org.:
- Univ. of Maryland, College Park, MD (United States)

- Sponsoring Org.:
- USDOE

- OSTI Identifier:
- 1466417

- Alternate Identifier(s):
- OSTI ID: 1498929

- Grant/Contract Number:
- FG02-93ER40762

- Resource Type:
- Published Article

- Journal Name:
- Physical Review D

- Additional Journal Information:
- Journal Name: Physical Review D Journal Volume: 98 Journal Issue: 3; Journal ID: ISSN 2470-0010

- Publisher:
- American Physical Society (APS)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS

### Citation Formats

```
Cohen, Thomas D., Lamm, Henry, and Lebed, Richard F. Tests of the standard model in B → D ℓ ν ℓ , B → D * ℓ ν ℓ and B c → J / ψ ℓ ν ℓ. United States: N. p., 2018.
Web. doi:10.1103/PhysRevD.98.034022.
```

```
Cohen, Thomas D., Lamm, Henry, & Lebed, Richard F. Tests of the standard model in B → D ℓ ν ℓ , B → D * ℓ ν ℓ and B c → J / ψ ℓ ν ℓ. United States. doi:10.1103/PhysRevD.98.034022.
```

```
Cohen, Thomas D., Lamm, Henry, and Lebed, Richard F. Thu .
"Tests of the standard model in B → D ℓ ν ℓ , B → D * ℓ ν ℓ and B c → J / ψ ℓ ν ℓ". United States. doi:10.1103/PhysRevD.98.034022.
```

```
@article{osti_1466417,
```

title = {Tests of the standard model in B → D ℓ ν ℓ , B → D * ℓ ν ℓ and B c → J / ψ ℓ ν ℓ},

author = {Cohen, Thomas D. and Lamm, Henry and Lebed, Richard F.},

abstractNote = {A number of recent experimental measurements suggest the possibility of a breakdown of lepton (ℓ) universality in exclusive b → cℓνℓ semileptonic meson decays. We analyze the full differential decay rates for several such processes, and show how to extract combinations of the underlying helicity amplitudes that are completely independent of m ℓ. Ratios of these combinations for different ℓ (as well as some combinations for a single value of ℓ) therefore equal unity in the standard model and provide stringent tests of lepton universality. Furthermore, the extractions assume the form of weighted integrals over the differential decay rates and therefore are useful even in situations where data in some regions of allowed phase space may be sparse.},

doi = {10.1103/PhysRevD.98.034022},

journal = {Physical Review D},

number = 3,

volume = 98,

place = {United States},

year = {2018},

month = {8}

}

DOI: 10.1103/PhysRevD.98.034022

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