Measurement of open beauty production in photoproduction at HERA

ZEUS Collaboration; J. Breitweg

doi:10.1007/s100520100571

paper

Measurement of open beauty production in photoproduction at HERA

arXiv:hep-ex/0011081 · doi:10.1007/s100520100571

Abstract

The production and semi-leptonic decay of heavy quarks have been studied in the photoproduction process $e^{+} p - > e^{+} + d ij e t + e^{-} + X w i t h t h e Z E U S d e t ec t or a t H E R A u s in g anin t e g r a t e d l u min os i t y o f 38.5$ {\rm pb^{-1}} $. E v e n t s w i t h p h o t o n - p r o t o n ce n t r e - o f - ma sse n er g i es,$ W_{Î³p} $, b e tw ee n 134 an d 269 G e V an d a p h o t o n v i r t u a l i t y, Q^{2}, l ess t han 1$ {\rm GeV^2} $w er ese l ec t e d r e q u i r in g a tl e a s ttw o j e t so f t r an s v er see n er g y$ E_T^{\rm jet1(2)} >7(6) $G e V an d an e l ec t r o nin t h e f ina l s t a t e . T h ee l ec t r o n s w er e i d e n t i f i e d b y e m pl oy in g t h e i o ni s a t i o n e n er g y l oss m e a s u r e m e n t . T h eco n t r ib u t i o n o f b e a u t y q u a r k s w a s d e t er min e d u s in g t h e t r an s v er se m o m e n t u m o f t h ee l ec t r o n r e l a t i v e t o t h e a x i so f t h ec l oses t j e t,$ p_T^{\rm rel} $. T h e d a t a, a f t er ba c k g r o u n d s u b t r a c t i o n, w er e f i tw i t ha M o n t e C a r l os im u l a t i o nin c l u d in g b e a u t y an d c ha r m d ec a y s . T h e m e a s u r e d b e a u t y cr osssec t i o n w a se x t r a p o l a t e d t o t h e p a r t o n l e v e l w i t h t h e b q u a r k r es t r i c t e d t o t h er e g i o n o f t r an s v er se m o m e n t u m$ p_T^{b} > p_T^{\rm min} = $5 G e V an d p se u d or a p i d i t y$ |Î·^{b}| < $2. T h ee x t r a p o l a t e d cr osssec t i o ni s$ 1.6 \pm 0.4 (stat.)^{+0.3}_{-0.5} (syst.) ^{+0.2}_{-0.4} (ext.) {nb}$. The result is compared to a perturbative QCD calculation performed to next-to-leading order.

21 pages, 9 figures, Accepted by Eur. Phys. J. C, Revised version has a corrected author list and implements comments from the referee