I have similar experience while using Ubuntu 14.10: cursor jumps around whenever I brush my palm against the touchpad.
I've tried a number of approaches to resolve this. First, I can go into "System Settings" => "Mouse & Touchpad" panel and turn the touchpad off. That works, but I'm afraid of what happens if/when my mouse dies or I forget to take it with me. (It's a wireless mouse.) So I'm trying to write a toggle script.
First approach was toggling 'synclient TouchpadOff' status. I found that using 'sudo synclient TouchpadOff=<0|1>' temporarily set a new status (confirmed by immediately doing 'synclient | grep TouchpadOff'), but afterward changes between 0 & 2 (when looping on this query).
So I'm using the this approach:
enable: xinput --enable
disable: xinput --disable
where 'dev_id' is found using 'xinput list' and searching for an appropriate entry. (My synaptics touchpad was listed as 'MSFT0001:00 06CB:75BD UNKNOWN' w/ id=13.) This seems to work (turn touchpad off|on), but doesn't appear to set TouchpadOff status (remains at 2), so I cannot really write an effective toggle function. Also, using xinput seems to conflict w/ using the "Mouse & Touchpad" gui, so if I've disabled it using xinput, I found that I have to toggle it off then on in the gui to get it back in sync. Sigh... Still, the purpose of the script should be to turn it back on if/when the mouse is MIA.
Next step is to put it somewhere (Launcher?) so that I can get to it thru keyboard strokes should my mouse not be available.
I believe that Microsoft's solution is to allow the touchpad to be disabled when a mouse is detected, but will immediately turn it back on when no longer detected. (I think that's how it works...) Also, working under Windows 8.1, I find I've not had to deal with the touchpad sensitivity much at all, so they must have set proper parameter values for the touchpad. Maybe Ubuntu could add a similar option to Mouse & Touchpad dialog panel, to turn off the touchpad whenever a mouse is detected. Tough part would be to turn it back on if mouse is no longer detected. Thoughts???
Finally, does anyone know if there's a way to detect/determine the brush of one's palm and basically ignore it? I turned PalmDetect on, but don't know what values to use for PalmMinWidth and PalmMinZ to effectively desensitize the touchpad when a palm brush happens. Any suggestions? I've set them both to large (500) and small (5) values, but still when I'm typing the cursor jumps, sometimes completely out of the window, sometimes to other locations in the current document. Any suggestions??? I'd love to have the option of using the touchpad, but its hypersensitivity to palm brushes is driving me crazy!!
I'm going to finish my script using 'xinput --disable' (difficulty recognizing which device is listed by 'xinput list'...), dock it somewhere, read up on keyboard shortcuts, then test out the scenario of mouse battery going dead or unplugging the usb sender from my laptop. If anyone has any further suggestions, I'd be willing to try them. (Haven't yet tried the /etc/X11/xorg.conf.d/70-synaptics.conf suggestion listed above; I'll probably try that tomorrow.)
BTW, on my old laptop, I was running Slackware using fvwm2, could never figure out how to turn off the touchpad, so resorted to a low-tech solution: covered the entire touchpad with a thin piece of metal taped on w/ duct tape!!