\section{Typography}
\label{sec:typography}
The use of the \latex typesetting symbols defined in the file
\texttt{lhcb-symbols-def.tex} and detailed in the appendices of this
document is strongly encouraged as it will make it much easier to
follow the recommendation set out below.
\begin{enumerate}
\item \lhcb is typeset with a normal (roman) lowercase b.
\item Titles are in bold face, and usually only the first word is
capitalised.
\item Mathematical symbols and particle names should also be typeset
in bold when appearing in titles.
\item Units are in roman type, except for constants such as $c$ or $h$
that are italic: \gev, \gevcc. The unit should be separated from
the value with a thin space (``\verb!\,!''),
and they should not be broken over two lines.
Correct spacing is automatic when using predefined units inside math mode: \verb!$3.0\gev$! $\to 3.0\gev$.
Spacing goes wrong when using predefined units outside math mode AND forcing extra space:
\verb!3.0\,\gev! $\to$ 3.0\,\gev or worse: \verb!3.0~\gev! $\to$ 3.0~\gev.
\item If factors of $c$ are kept, they should be used both for masses and
momenta, \eg $p=5.2\gevc$ (or $\gev c^{-1}$), $m = 3.1\gevcc$ (or $\gev c^{-2}$). If they are dropped this
should be done consistently throughout, and a note should be added
at the first instance to indicate that units are taken with $c=1$.
Note that there is no consensus on whether decay widths $\Gamma$ are
in \mev or \mevcc (the former is more common).
Both are accepted if consistent.
\item The \% sign should not be separated from the number that precedes it: 5\%, not 5 \%.
A thin space is also acceptable: 5\,\%, but should be applied consistently throughout the paper.
\item Ranges should be formatted consistently. The recommended form is to use a dash with no spacing around it:
7--8\gev, obtained as \verb!7--8\gev!. Another possibility is ``7 to 8\gev''.
\item Italic is preferred for particle names (although roman is
acceptable, if applied consistently throughout). Particle Data
Group conventions should generally be followed: \Bd (no need for a
``d'' subscript), \decay{\Bs}{\jpsi\phi}, \Bsb,
(note the long bar, obtained with \verb!\overline!, in contrast to the discouraged short \verb!\bar{B}! resulting in $\bar{B}$), \KS (note the
uppercase roman type ``S'').
This is most easily achieved by using the predefined symbols described in
Appendix~\ref{sec:listofsymbols}.
Italic is also used for particles whose name is an uppercase Greek letter:
\Upsilonres, \Deltares, \Xires, \Lambdares, \Sigmares, \Omegares, typeset as
\verb!\Upsilonres!, \verb!\Deltares!, \verb!\Xires!, \verb!\Lambdares!, \verb!\Sigmares!, \verb!\Omegares! (or with the appropriate macros adding charge and subscripts). Paper titles in the bibliography must be adapted accordingly.
Note that the \Lz baryon has no zero, while the \Lb baryon has one. That's historical.
\item Unless there is a good reason not to, the charge of a particle should be
specified if there is any possible ambiguity
($m(\Kp\Km)$ instead of $m(KK)$, which could refer to neutral kaons).
\item Decay chains can be written in several ways, depending on the complexity and the number of times it occurs. Unless there is a good reason not to, usage of a particular type should be consistent within the paper.
Examples are:
\decay{\Dsp}{\phi\pip}, with \decay{\phi}{\Kp\Km};
\decay{\Dsp}{\phi\pip} (\decay{\phi}{\Kp\Km});
\decay{\Dsp}{\phi(}{\Kp\Km)\pip}; or
\decay{\Dsp}{[\Kp\Km]_\phi\pip}.
\item Variables are usually italic: $V$ is a voltage (variable), while
1 V is a volt (unit). Also in combined expressions: $Q$-value, $z$-scale, $R$-parity \etc
\item Subscripts and superscripts are roman type when they refer to a word (such as T
for transverse) and italic when they refer to a variable (such as
$t$ for time): \pt, \dms, $t_{\mathrm{rec}}$.
% This is a test: $f_{\pt}$.
\item Standard function names are in roman type: \eg $\cos$, $\sin$
and $\exp$.
\item Figure, Section, Equation, Chapter and Reference should be
abbreviated as Fig., Sect. (or alternatively Sec.), Eq., Chap.\ and
Ref.\ respectively, when they refer to a particular (numbered) item,
except when they start a sentence. Table and Appendix are not
abbreviated. The plural form of abbreviation keeps the point after
the s, \eg Figs.~1 and~2. Equations may be referred to either with
(``Eq.~(1)'') or without (``Eq.~1'') parentheses,
but it should be consistent within the paper.
\item Common abbreviations derived from Latin such as ``for example''
(\eg), ``in other words'' (\ie), ``and so forth'' (\etc), ``and
others'' (\etal), ``versus'' (\vs) can be used, with the typography
shown, but not excessively; other more esoteric abbreviations should be avoided.
\item Units, material and particle names are usually lower case if
spelled out, but often capitalised if abbreviated: amps (A), gauss
(G), lead (Pb), silicon (Si), kaon (\kaon), but proton (\proton).
%\item The prefix for 1000 (k, \eg kV) should not be confused with
% that used in computing (K, which strictly speaking denotes $2^{10}$,
% \eg KB).
\item Counting numbers are usually written in words if they start a
sentence or if they have a value of ten or below in descriptive
text (\ie not including figure numbers such as ``Fig.\ 4'', or
values followed by a unit such as ``4\,cm'').
The word 'unity' can be useful to express the special meaning of
the number one in expressions such as:
``The BDT output takes values between zero and unity''.
% Numbers should not be
% written as words if they by nature are real numbers that happen to
% take an integer value, such as $\chisq/\mathrm{ndf} < 4$.
\item Numbers larger than 9999 have a small space between
the multiples of thousand: \eg 10\,000 or 12\,345\,678. The decimal
point is indicated with a point rather than a comma: \eg 3.141.
\item We apply the rounding rules of the
PDG~\cite{PDG2018}. The basic rule states that if the three
highest order digits of the uncertainty lie between 100 and 354, we round
to two significant digits. If they lie between 355 and 949, we round
to one significant digit. Finally, if they lie between 950 and 999,
we round up and keep two significant digits. In all cases,
the central value is given with a precision that matches that of the
uncertainty. So, for example, the result $0.827 \pm 0.119$ should be
written as $0.83\pm 0.12$, $0.827\pm 0.367$ should turn into
$0.8\pm 0.4$, and $14.674\pm0.964$ becomes $14.7\pm1.0$.
When writing numbers with uncertainty components from
different sources, \ie statistical and systematic uncertainties, the rule
applies to the uncertainty with the best precision, so $0.827\pm
0.367\stat\pm 0.179\syst$ goes to $0.83\pm 0.37\stat\pm 0.18\syst$ and
$8.943\pm 0.123\stat\pm 0.995\syst$ goes to $8.94\pm 0.12\stat\pm
1.00\syst$.
\item When rounding numbers, it should be avoided to pad with zeroes
at the end. So $51237 \pm 4561$ should be rounded as $(5.12 \pm 0.46)
\times 10^4$ rather than $51200 \pm 4600$. Zeroes are accepted for yields.
\item When rounding numbers in a table, some variation of the rounding
rules above may be required to achieve uniformity.
\item Hyphenation should be used where necessary to avoid ambiguity,
but not excessively. For example: ``big-toothed fish'' (to indicate
that big refers to the teeth, not to the fish), but ``big white
fish''. A compound modifier often requires hyphenation
(\CP-violating observables, \bquark-hadron decays, final-state
radiation, second-order polynomial), even if the same combination in
an adjective-noun combination does not (direct \CP violation, heavy
\bquark hadrons, charmless final state). Adverb-adjective
combinations are not hyphenated if the adverb ends with 'ly':
oppositely charged pions, kinematically similar decay. Words
beginning with ``all-'', ``cross-'', ``ex-'' and ``self-'' are
hyphenated \eg\ cross-section and cross-check. ``two-dimensional''
is hyphenated. Words beginning with small prefixes (like ``anti'',
``bi'', ``co'', ``contra'', ``counter'', ``de'', ``extra'', ``infra'',
``inter'', ``intra'', ``micro'', ``mid'', ``mis'', ``multi'', ``non'', ``over'',
``peri'', ``post'', ``pre'', ``pro'', ``proto'', ``pseudo'', ``re'', ``semi'',
``sub'', ``super'', ``supra'', ``trans'', ``tri'', ``ultra'', ``un'', ``under'' and
``whole'') are single words and should not be hyphenated
\eg\ semileptonic, pseudorapidity, pseudoexperiment, multivariate,
multidimensional, reweighted,\footnote{Note that we write weighted unless it's the second weighting} preselection, nonresonant, nonzero,
nonparametric, nonrelativistic, antiparticle,
misreconstructed and misidentified.
\item Minus signs should be in a proper font ($-1$), not just hyphens
(-1); this applies to figure labels as well as the body of the text.
In \latex, use math mode (between \verb!$$!'s) or make a dash (``\verb!--!'').
In ROOT, use \verb!#minus! to get a normal-sized minus sign.
\item Inverted commas (around a title, for example) should be a
matching set of left- and right-handed pairs: ``Title''. The use of
these should be avoided where possible.
\item Single symbols are preferred for variables in equations, \eg\
\BF\ rather than BF for a branching fraction.
\item Parentheses are not usually required around a value and its
uncertainty, before the unit, unless there is possible ambiguity: so
\mbox{$\dms = 20 \pm 2\invps$} does not need parentheses,
whereas \mbox{$f_d = (40 \pm 4)$\%} or \mbox{$x=(1.7\pm0.3)\times 10^{-6}$} does.
The unit does not need to be repeated in
expressions like \mbox{$1.2 < E < 2.4\gev$}.
\item The same number of decimal places should be given for all values
in any one expression (\eg \mbox{$5.20 < m_B < 5.34\gevcc$}).
\item Apostrophes are best avoided for abbreviations: if the abbreviated term
is capitalised or otherwise easily identified then the plural can simply add
an s, otherwise it is best to rephrase: \eg HPDs, pions, rather
than HPD's, \piz's, $\pion$s.
\item Particle labels, decay descriptors and mathematical functions are not nouns, and need often to be followed by a noun.
Thus ``background from \decay{\Bd}{\pip\pim} decays'' instead of ``background from \decay{\Bd}{\pip\pim}'',
and ``the width of the Gaussian function'' instead of ``the width of the Gaussian''.
\item In equations with multidimensional integrations or differentiations, the differential terms should be separated by a thin space and the $\rm d$ should be in roman.
Thus $\int f(x,y) {\rm d}x\,{\rm d}y$ instead $\int f(x,y) {\rm d}x{\rm d}y$ and
$\frac{{\rm d}^2\Gamma}{{\rm d}x\,{\rm d}Q^2}$ instead of $\frac{{\rm d}^2\Gamma}{{\rm d}x{\rm d}Q^2}$.
% The d's are allowed in either roman or italic font, but should be consistent throughout the paper.
\item Double-barrelled names are typeset with a hyphen (\verb!-!), as in Gell-Mann, but joined named use an n-dash (\verb!--!), as in Breit--Wigner.
\item Avoid gendered words. Mother is rarely needed. Daughter can be a decay product or a final-state particle. Bachelor can be replaced by companion.
\end{enumerate}
