  Proton-philic spin-dependent inelastic Dark Matter is a Weakly Inelastic
Massive Particle scenario that can explain the DAMA yearly modulation effect in
compliance with the constraints from other direct detection Dark Matter
searches. We obtain updated ranges for its parameters both in a
halo-independent approach and adopting a truncated Maxwellian for the WIMP
velocity distribution constructing approximate frequentist confidence intervals
from an effective chi-square including, among others, the latest experimental
constraints from XENON1T, PANDAX-II, SuperCDMS and CDMSlite. In the
halo-independent analysis we have implemented the dependence on the WIMP
velocity distribution through a step-wise parameterization of the halo
function. For the calculation of the profile likelihood we used a Markov Chain
Montecarlo generator that required a large number of evaluations of the
expected rates. To reduce computational time we introduced expected rates
expressions suitable for a fast evaluation through tabulation and
interpolation. Our frequentist analysis confirms the present viability of the
pSIDM scenario as a possible explanation of the DAMA effect. In terms of the
WIMP mass $m_{\chi}$ and of the mass splitting $\delta$ we find the 1-sigma
ranges $\mbox{12.5 GeV} \le m_{\chi}\le \mbox{15.7 GeV}$, $\mbox{22.1 keV} \le
\delta \le \mbox{26.1 keV}$ for the halo--independent analysis and $\mbox{11.4
GeV} \le m_{\chi}\le \mbox{13.6 GeV}$, $\mbox{24.4 keV} \le \delta \le
\mbox{27.0 keV}$ for the Maxwellian case. We find that a full year of data
taking of XENON1T should allow to start probing the pSIDM scenario.

High Energy Physics - Phenomenology