Sandra Luna, Pizza Express

That all the events reviewed here should be part of the London Jazz Festival says something about both world music and jazz: while "jazz" is defined ever more broadly, "world music" proves ever less suited to ghettoisation. But tango is the great uniter, and certainly was in the civilised ambience of the Dean Street Pizza Express, where Sandra Luna was promoting her new CD, Tango Varon. For this charismatic exponent - who started singing in Buenos Aires clubs when she was six - tango is "cinders" that burn again and again, and her repertoire of songs, including Carlos Gardel classics, confirmed its self-renewing power. Her pianist was Lisztian in both sound and look; her bandoneonist's ice-pure cascades perfectly offset her own combination of coquetry, sensuality and menace.

Women of Cape Verde was designed to show what vocal talent those rocky islands possess besides the great Cesaria Evora, and if one of the three we heard - Maria Alice - was a lighter, sweeter variant on the Barefoot Diva, the other two, with their songs drawn from Portuguese/African fusions, were exciting new discoveries. Nancy Vieira put her strong, clean tone and boyish good looks to effective use with a series of funanas and batuques, backed by a five-man acoustic band; her way of lazily swooping up to the note was quintessentially Cape Verdean. The flamboyantly leonine Lura, meanwhile, was dynamite: with a voice that modulated from a dreamy whisper to a ferocious shout, and with an act that was first comic, then sexually provocative, then rabble-rousing, she turned the Purcell Room into a stadium. When her international career gets going, this girl will fill stadiums.

I was curious to see how Rabih Abou-Khalil would meld his oud with the jazz combo of clarinet, accordion, tuba, and drums: the strength of the oud lies in its dusty, harmonic-filled resonance, and in the ancient Arabic culture it conveys. Had this tirelessly experimental Lebanese player gone too far this time? I think so. The clarinet's capacity to bend notes allowed it to meet the oud half way, but the crude amplification did no favours to Rabih's naturally refined sound.

The amplification was so good for Ghazal's concert the following night that every echo and eddy from this brilliant trio was cherished. Shujaat Hussain Khan's sitar, Kayhan Kalhor's spike-fiddle, and Sandeep Das's tabla came together in one of the most perfectly judged fusions I've ever heard: we knew from their ECM CD how successfully they could blend Persian and Indian traditions, and this concert was living proof.