There are 2 notions of packages here and they are not the same.
First, there is the TeX Live idea of a package, such as
helvetic. Here is what the TeX Live Manager has to say about it:
$ tlmgr info helvetic
shortdesc: URW "Base 35" font pack for LaTeX.
longdesc: A set of fonts for use as "drop-in" replacements for Adobe's basic set, comprising: - Century Schoolbook (substituting for Adobe's New Century Schoolbook); - Dingbats (substituting for Adobe's Zapf Dingbats); - Nimbus Mono L (substituting for Abobe's Courier); - Nimbus Roman No9 L (substituting for Adobe's Times); - Nimbus Sans L (substituting for Adobe's Helvetica); - Standard Symbols L (substituting for Adobe's Symbol); - URW Bookman; - URW Chancery L Medium Italic (substituting for Adobe's Zapf Chancery); - URW Gothic L Book (substituting for Adobe's Avant Garde); and - URW Palladio L (substituting for Adobe's Palatino).
sizes: run: 2377k
cat-date: 2012-06-06 22:57:48 +0200
Second, there is the LaTeX sense of a 'package' which you can load to use in your document using
In some cases, there may be a package in both senses. But, in others, there will not be.
helvetic provides the fonts but there is no LaTeX package by that name, as you have discovered. That is,
helvetic is not identical with the LaTeX package which you need to use those fonts in your document.
helvet is the LaTeX package which you need for that.
helvet is provided by the TeX Live package
$ tlmgr info psnfss
shortdesc: Font support for common PostScript fonts.
longdesc: Font definition files, macros and font metrics for freely- available Adobe Type 1 fonts. The font set consists of the 'LaserWriter 35' set (originally 'freely available' because embedded in PostScript printers), and a variety of other free fonts, together with some additions. Note that while many of the fonts are available in PostScript (and other) printers, most publishers require fonts embedded in documents, which requires that you have the fonts in your TeX system. Fortunately, there are free versions of the fonts from URW (available in the URW base5 bundle). The base set of text fonts covered by PSNFSS are: AvantGarde, Bookman, Courier, Helvetica, New Century Schoolbook, Palatino, Symbol, Times Roman and Zapf Dingbats. In addition, the fonts Bitstream Charter and Adobe Utopia are covered (those fonts were contributed to the Public Domain by their commercial foundries). Separate packages are provided to load each font for use as main text font. The packages helvet (which allows Helvetica to be loaded with its size scaled to something more nearly appropriate for its use as a Sans-Serif font to match Times) and pifont (which provides the means to select single glyphs from symbol fonts) are tailored to special requirements of their fonts. Mathematics are covered by the mathptmx package, which constructs passable mathematics from a combination of Times Roman, Symbol and some glyphs from Computer Modern, and by Pazo Math (optionally extended with the fpl small-caps and old-style figures fonts) which uses Palatino as base font, with the mathpazo fonts. The bundle as a whole is part of the LaTeX 'required' set of packages.
sizes: src: 73k, doc: 521k, run: 441k
cat-date: 2012-07-23 15:04:13 +0200