Beyoncé:

On December 13, 2013, Beyoncé unexpectedly released her eponymous fifth studio album on the iTunes Store without any prior announcement or promotion. The album debuted atop the Billboard 200 chart, giving Beyoncé her fifth consecutive number-one album in the US. This made her the first woman in the chart's history to have her first five studio albums debut at number one. Beyoncé received critical acclaim and commercial success, selling one million digital copies worldwide in six days; The New York Times noted the album's unconventional, unexpected release as significant. Musically an electro-R&B album, it concerns darker themes previously unexplored in her work, such as "bulimia, postnatal depression [and] the fears and insecurities of marriage and motherhood". The single "Drunk in Love", featuring Jay Z, peaked at number two on the Billboard Hot 100 chart. In April 2014, after much speculation in the weeks before, Beyoncé and Jay Z officially announced their On the Run Tour. It served as the couple's first co-headlining stadium tour together. On August 24, 2014, she received the Video Vanguard Award at the 2014 MTV Video Music Awards. Knowles also took home three competitive awards: Best Video with a Social Message and Best Cinematography for "Pretty Hurts", as well as best collaboration for "Drunk in Love". In November, Forbes reported that Beyoncé was the top-earning woman in music for the second year in a row—earning $115 million in the year, more than double her earnings in 2013. Beyoncé was reissued with new material in three forms: as an extended play, a box set, as well as a full platinum edition.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". Who joined Beyonce on her On The Run Tour?
Jay Z