Is M_{Pl} the Planck mass or the reduced Planck mass?

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Discussion Overview

The discussion revolves around the interpretation of the symbol M_{Pl} in the context of the Planck (CMB) collaboration's observation papers. Participants are questioning whether M_{Pl} refers to the Planck mass or the reduced Planck mass, exploring the definitions and usage of these terms in the literature.

Discussion Character

  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant inquires about the specific value of M_{Pl} used in Planck collaboration papers and whether it denotes the Planck mass or the reduced Planck mass.
  • Another participant references the NIST webpage to provide the value of the Planck mass but seeks clarification on what is meant by "reduced" Planck mass.
  • A participant mentions that the reduced Planck mass is defined in literature but notes the interchangeable use of M_{Pl} for both masses in various papers.
  • Several participants suggest looking at specific sources, including ESA's Planck website and related articles, for the value of m_pl used in the context.
  • One participant proposes a notation convention for indicating the reduced Planck mass, suggesting the use of a diagonal line through the letters in the subscript to avoid confusion.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the consistent definition of M_{Pl} in the literature, indicating that there is no clear consensus on whether it refers to the Planck mass or the reduced Planck mass.

Contextual Notes

The discussion highlights the ambiguity in the notation used in various papers and the potential for misinterpretation due to inconsistent typesetting practices.

Alpha2021
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What is the value of M_{Pl} used in the Planck (CMB) collaboration's observation papers, such as the one referenced in this link: https://arxiv.org/pdf/1807.06211.pdf. Specifically, I am wondering if it refers to the Planck mass or the reduced Planck mass?
 
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Thanks for your kind reply.
Definition of reduced Planck mass can be found here.
The problem is that M_{Pl} is used in the literature interchangeably as Planck mass or reduced Planck mass. Did you see anywhere in Planck's papers where they define M_{Pl}?
 
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I found in

https://www.cosmos.esa.int/web/planck
> https://www.aanda.org/articles/aa/full_html/2020/09/aa33910-18/aa33910-18.html#S1
1683151818052.png

You may get value of m_pl they use.
 
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Alpha2021 said:
What is the value of M_{Pl} used in the Planck (CMB) collaboration's observation papers, such as the one referenced in this link: https://arxiv.org/pdf/1807.06211.pdf. Specifically, I am wondering if it refers to the Planck mass or the reduced Planck mass?
Better practice, although you are right in asking as some authors are sloppy in their typesetting, is to indicate the reduced Planck mass with diagonal line through the letters P or Pl in the subscript, just as one indicates the reduced Planck's constant with a diagonal link through the symbol "h" for Planck's constant.
 

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