Two identical non-relative particles A and B move right angles to each other, processing de Broglie wavelength \[{{\lambda }_{1}}\] and \[\,{{\lambda }_{2}}\], respectively. The de Broglie wavelength of each particle in their center of mass frame of reference is

• A. \[{{\lambda }_{1}}+{{\lambda }_{2}}\]
• B. \[2{{\lambda }_{1}}{{\lambda }_{2}}/\left( \sqrt{\lambda _{1}^{2}+\lambda _{2}^{2}} \right)\]
• C. \[2{{\lambda }_{1}}{{\lambda }_{2}}/\left( \sqrt{\left| \lambda _{1}^{2}+\lambda _{2}^{2} \right|} \right)\]
• D. \[\left( {{\lambda }_{1}}+{{\lambda }_{2}} \right)/2\]