Diffractive open charm production at HERA

Levin, E.M.; Martin, Alan D.; Ryskin, M.G.; Teubner, T.

doi:10.1007/s002880050431

Diffractive open charm production at HERA

E.M. Levin
(
- Durham U. and
- Rio de Janeiro, CBPF and
- St. Petersburg, INP
)
,
Alan D. Martin
(
- Durham U.
)
,
M.G. Ryskin
(
- Durham U. and
- St. Petersburg, INP
)
,
T. Teubner
(
- Durham U.
)

Jun, 1996

34 pages

Published in:

Z.Phys.C 74 (1997) 671-685

e-Print:

hep-ph/9606443 [hep-ph]

DOI:

10.1007/s002880050431

Report number:

DTP-96-50

View in:

ADS Abstract Service

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Abstract:

We use perturbative QCD to calculate the cross sections

\sigma~{L,T}

for the diffractive production of open charm

(c\overline{c})

from longitudinally and transversely polarised photons (of virtuality

Q~2

) incident at high energy

(\sqrt{s})

on a proton target. We study both the

Q~2

and

M~2

dependence of the cross sections, where

M

is the invariant mass of the

c\overline{c}

pair. Surprisingly, the result for

\sigma~T

, as well as for

\sigma~L

, is perturbatively stable. We estimate higher-order corrections and find a sizeable enhancement of the cross sections. The cross sections depend on the {\it square} of the gluon density

g (x, K~2)

, and we show that the observation of open charm at the HERA electron-proton collider can act as a sensitive probe of the gluon distribution for

x = (Q~2 + M~2)/s

and scale

K~2 = (m_c~2 + \langle k_T~2 \rangle) (1 + Q~2/M~2)

where the average quark transverse momentum squared

\langle k_T~2 \rangle \sim m_c~2

. As compared to diffractive

J/\psi

production, open charm has the advantage that it is independent of the non-perturbative ambiguities arising from the

J/\psi

wave function. We estimate the fraction of diffractive events that arise from

c\overline{c}

production.

Note:

34 pages, LaTeX, 15 Postscript figures included using epsf. The complete paper, including figures, is also available via anonymous ftp at ftp://cpt1.dur.ac.uk/pub/preprints/dtp96/dtp9650/ Report-no: DTP/96/50

electron p: deep inelastic scattering
deep inelastic scattering: electron p
exchange: one-photon
one-photon: exchange
photon p: interaction
interaction: photon p
diffraction
quark: charm
quark: electroproduction
electroproduction: quark

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