Search Guide

Our search engine tries to offer today's typical web searching experience, as gained with popular search engines such as Google. The nature of bibliographic searching differs from that of a web page searching, though. We provide many extensions to enable a complex and precise structured search, including an combined metadata, fulltext and reference search in one go. This page lists several tips and tricks that you may find useful to this effect.

    Simple versus advanced search
    Search guidance
    Searching for words versus phrases
    Boolean queries
    Special characters and punctuation
    International characters
    Word truncation/stemming
    Structured metadata search

Simple versus advanced search

The default search mode is simple search that basically provides you with one input box where you can type your query, followed by a possibility to choose one of the common indexes to search within. You would usually simply type the keywords you are interested in and hit return. For example, if you are interested in documents on standard model that are written by (or mention) Ellis, you would type:

and on the search results page you could further add/remove keywords to get more precisely at what you are looking for, as is mentioned below.

The advanced search interface provides you with explicit tools to play with: you can change the matching type from the default word matching to phrase searching or the regular matching; you can use boolean queries in several indexes, etc. For example, to find all the documents written by Ellis, J spelled exactly that way that contain either of the words muon or neutrino in the title and that were published in 2001, you would type:


Note that Simple Search can provide you basically the same functionality, if you make use of special syntax that is explained in the text below. The simple-versus-advanced does not refer to the functionality that is being provided but rather to the amount of parametrization you can "tweak". We conform to the common use of the simple/advanced terms as found in other search engines.

Much of what follows will deal with a question on "how a power user would use the simple search interface". Recall that you can always go to the Advanced Search for more query assistance.

Search guidance

After you submit your query, the search engine will analyze it and will try to always guide you in case no exact match could be found. For example, it would print you a list of closest indexed terms in case of spelling troubles:

Alternative choices will be printed in red. The search engine will similarly warn you when your search terms could not be found, or when they could but your boolean query couldn't be met. The search engine will also silently try to search for alternative forms (e.g. remove punctuation), etc.

Thanks to multiple search stages and the guidance provided at each stage, it is usually sufficient to simple type what you are looking for and see what the system says in return. If you aren't satisfied, you would then add/remove words from your query until the satisfactory reply.

Searching for words versus phrases

The default search mode is a search for words. This means that any whitespace you type is not significant, but is rather interpreted to mean "add an automatic boolean AND between words", like Google does. For example, to find all records that contain both the word ellis and the word muon anywhere in the record, type:

The whitespace would be significant if you include it within quotes. There are two phrase searching modes:
  1. The double quotes instruct the search engine to search for exact phrase. This phrase search mode will match if and only if the given metadata field is exactly equal to the input pattern. For example, to find all documents written by Ellis, J spelled exactly that way, type:
  2. The single quotes instruct the search engine to search for partial phrase. Unlike the exact phrase search, this mode allows for an extra text appearing before/after given pattern. This is somewhat similar to the "phrase search mode" common on Google and other fulltext engines that search for phrase expressions inside Web pages. For example, to find all the titles containing the expression muon decay regardless of the position of the expression in the title, type:
    Now you see how to search for an author spelled sometimes as Ellis, J and sometimes as Ellis, Jonathan Richard (and other authors, such as De Lellis, Jim) at the same time:
    (See also our specific author searching tips.)

The difference between exact and partial phrase searching modes may not be obvious upon first look. While the latter is more similar to what ``phrase search'' usually means in the context of web page search engines, the former one is usually an order of magnitude faster if you know the precise values you are looking for.

Another interesting searching mode besides the word and phrase searches is the regular expression search, introduced by slashes instead of quotes. For example, the above partial phrase query 'muon decay' is fully equivalent to the regular expression query /muon decay/. The regular expression syntax is very powerful and permits you to construct very complex queries. For more information, please consult the regular expression section of this guide.

Boolean queries

We have already seen how whitespace adds a silent boolean AND in the search for words. The other boolean operators include:
ellis +muon matches all records that contain both the word ellis and the the word muon
ellis muon ditto, syntactic sugar
ellis and muon ditto, syntactic sugar
ellis -muon matches all records that contain the word ellis but that do not contain the word muon
ellis not muon ditto, syntactic sugar
ellis |muon matches all records that contain at least one of the words
ellis or muon ditto, syntactic sugar

Logical operations are automatically chained from left to right. For example, if you want to search for documents written by Ellis on muons or kaons, write:

which looks for (muon or kaon) and ellis. Note that this gives different results from:
which would search for (ellis and muon) or kaon.

The left-to-right chaining behaviour permits you to easily refine your search by adding/removing words with and/not or +/- operators. For example, to exclude the documents on decay from the above search, append -decay:

to get a refined list. Keep adding/removing terms until you are satisfied.


You can also use parentheses in your queries to group boolean expressions together:

This query returns records containing either gravity or supergravity, and either ellis or perelstein anywhere in the record.

Note that you can use any number of parentheses in the query. Nested parentheses, such as foo AND (bar OR (fuux NOT quux)), are also supported.

Special characters and punctuation

When indexing words, an attention is paid to index it both with and without punctuation, so that you should be able to search for terms containing special characters, such as C++, verbatim:

For example, to find records containing the LaTeX expression $e^{+}e^{-}$ in the title, type:
For example, to find document with the report number hep-ph/0204133, type:
Note that the search is case-insensitive:

International characters

The search engine works with Unicode UTF-8 so you can type your query strings in any language stored in the database. For example, to find the documents written by (or on) Пушкин, type:

Note that you don't have to type accents to find accented results. For example, type Lemaitre to find papers by Lemaître:
Currently, words that include accented characters can only be retrieved by entering accented characters in the query.

Word truncation/stemming

The word truncation is supported via asterisk (*) wildcard character. The wildcard instructs the search engine to match any number of characters in that place. For example, to find records that contain words muon, muons, muonic etc, type:

The wildcard query works both in prefix and infix position. For example, to get all the words that start by CERN-TH and end by 31, type:
Note that the wildcard will be ignored if you try to apply it to very short words, such as a*:
The wildcard character can be used also in the phrase searching mode. For example, to find all the documents whose title starts by "Neutrino mass", type:
Recall that we have introduced exact and partial phrase search modes. Actually, a partial phrase search mode launches an exact search enclosed within wildcards: we could say that 'foo bar baz' equals to "*foo bar baz*". Now you can see why the partial phrase search is slow: due to the usage of two asterisks in front and after the text, each and every title in the database has to be looked up to determine whether it matches or not. (There are currently no partial phrase indexes.)

Structured metadata search

Searching within various bibliograpic fields (such as title, author) is supported via Google's "site:" like syntax. If a search term is preceded by a field name and a colon, then the term is searched for inside this field only. For example, to find documents containing the word ellis within author index, type:

To select documents written by Ellis that contain words like muon, muons, muonic within title, type:
To select documents written by the NA60 experiment from the year 2001, type:
The most common fields you may want to use are author, title, reportnumber, abstract, keyword, year, experiment, fulltext, and reference.