When using NFC peer-to-peer communication (aka Android Beam) between two
Android (4.0+) devices, there is no way to avoid the Beam UI. So it is not
possible to transfer data without the "Touch to Beam".
Before Android Beam (effectively Android 2.3.3-2.3.7), this was possible
through foreground NDEF push (which is now (a) deprecated and (b) on
Android 4.0+ implemented through Beam). In that case NDEF messages where
immediately transfered without the "Push to Beam" window.
Only starting with Android 4.4, there is the possibility to communicate
between two Android devices over NFC without the Beam UI (actually without
using Android Beam and peer-to-peer mode at all): If both devices are 4.4+,
one device can use Android HCE to emulate a contactless smartcard and one
device can use the reader-mode API (this only works with the reader-mode
API introduced in 4.4, so both devices need to be 4.4+) to communicate with
the emulated smartcard.