Custom character for input - primefaces

Question

I am new to java, I am working with primefaces and as part of a capture for username I am being asked for this.
How can I customize the capture? You can capture numbers (0-9) and letters (a-zA-Z) but I also require: # $ & -_. How can I make special characters for this? Thanks in advance and an apology in case I do not ask the question correctly.
I already made several tests but I do not have the desired result. When I put the "&" character it marks me an error leaving it like this:
<o:validator
validatorId="javax.faces.RegularExpression"
pattern="^[#$-_.A-Za-z0-9\\+]+(\\.[#$-_.A-Za-z0-9]+)*"
message="La contraseña no tiene un formato válido." />
<p:outputLabel value="Contraseña:" for="newUserPwd1"/>
<p:password
id="newUserPwd1" value="#{userManagerView.pass1}" required="true"
requiredMessage ="La contraseña es obligatoria.">
<o:validator
validatorId="javax.faces.Length" minimum="6"
message="La contraseña requiere mínimo de 6 caracteres"/>
<o:validator
validatorId="javax.faces.RegularExpression"
pattern="^[#$-_.A-Za-z0-9\\+]+(\\.[#$-_.A-Za-z0-9]+)*"
message="La contraseña no tiene un formato válido." />
</p:password>
This is the error with the character &
Parsing Error /viewMetadata/admin/usuarios.xhtml: Error Traced [line: 172] A decimal representation must appear immediately after "& #
Caused by:
javax.faces.view.facelets.FaceletException - Error Parsing /viewMetadata/admin/usuarios.xhtml: Error Traced [line: 172] A decimal representation must appear immediately after "& #
at org.apache.myfaces.view.facelets.compiler.SAXCompiler.doCompileViewMetadata (SAXCompiler.java:838)