In the meeting today, Kechen present the preliminary results of measuring the inclusive neutral-current production of Higgs at the LHeC, which can be used to extract the model-independent HZZ coupling and finally the Higgs total decay width.
Since the z-momentum of the incoming quark p_z (or the center-of-mass energy sqrt(s) of the collision) is unknown, one cannot calculate the recoil mass directly as at the e-e+ colliders.
However, p_z can be solved as a function of m_{recoil}.
One can assuming m_{recoil} = m_h = 125 GeV and calculate the
corresponding p_z.
In this way, the whole distribution of the p_z can be used to reject the
backgrounds.
(1) Kechen's slides show that the p_z distribution of the incoming quark peaks around 600 GeV for the signal,
but the peak is not very sharp and it has a long tail.
Unfortunately, the background also has a similar distribution, which makes the
“recoil mass method” difficult to distinguishing between signal and background.
(2) Uta suggested that the center-of-mass energy could be measured by s=Q^2/(x*y).
One can rely only on FS particles to reconstruct Q^2, x and y using e.g. the double angle method for high Q^2 values.
Need better understanding this method at ep colliders.
(3) We need to understand how to estimate and suppress background process, such as DIS "p e- > j e- + X" process.