Search for tetraquark states X c c ¯ s ¯ s in D + s D + s ( D * + s D * + s ) final states at Belle

Abstract

A search for double-heavy tetraquark state candidates X c c ¯ s ¯ s decaying to D + s D + s and D * + s D * + s is presented for the first time using the data samples of 102 × 10 6

Υ ( 1 S ) and 158 × 10 6

Υ ( 2 S ) events, and the data samples at √ s = 10.52 , 10.58, and 10.867 GeV corresponding to integrated luminosities of 89.5, 711.0, and 121.4

fb − 1 , respectively, accumulated with the Belle detector at the KEKB asymmetric energy electron-positron collider. The invariant-mass spectra of the D + s D + s and D * + s D * + s are studied to search for possible resonances. No significant signals are observed, and the 90% confidence level upper limits on the product branching fractions [ B ( Υ ( 1 S , 2 S ) → X c c ¯ s ¯ s + anything ) × B ( X c c ¯ s ¯ s → D + s D + s ( D * + s D * + s ) ) ] in Υ ( 1 S , 2 S ) inclusive decays and the product values of Born cross section and branching fraction [ σ ( e + e − → X c c ¯ s ¯ s + anything ) × B ( X c c ¯ s ¯ s → D + s D + s ( D * + s D * + s ) ) ] in e + e − collisions at √ s = 10.52 , 10.58, and 10.867 GeV under different assumptions of X c c ¯ s ¯ s masses and widths are obtained.