Scope of self-interacting thermal WIMPs in a minimal U(1)D extension and its future prospects

Abstract

In this work we have considered a minimal extension of Standard Model by a local U(1) gauge group in order to accommodate a stable (fermionic) Dark Matter (DM) candidate. We have focussed on parameter regions where DM possesses adequate selfinteraction, owing to the presence of a light scalar mediator (the dark Higgs), alleviating some of the tensions in the small-scale structures. We have studied the scenario in the light of a variety of data, mostly from dark matter direct searches, collider searches and flavor physics experiments, with an attempt to constrain the interactions of the standard model (SM) particles with the ones in the Dark Sector (DS). Assuming a small gauge kinetic mixing parameter, we find that for rather heavy DM the most stringent bound on the mixing angle of the Dark Higgs with the SM Higgs boson comes from dark matter direct detection experiments, while for lighter DM, LHC constraints become more relevant. Note that, due to the presence of very light mediators, the effective operator approach to the direct detection is inapplicable here and these constraints have been re-evaluated for our scenario. In addition, we find that the smallness of the relevant portal couplings, as dictated by data, critically suppress the viability of DM production by the standard "freeze-out" mechanism in such simplified scenarios. In particular, the viable DM masses are O(2) GeV i.e. in the regions where direct detection limits tend to become weak. For heavier DM with large self-interactions, we hence conclude that non-thermal production mechanisms are favored. Lastly, future collider reach of such a simplified scenario has also been studied in detail.The evidence for existence of non-relativistic non-luminous Dark Matter (DM) has been overwhelming. Several astrophysical and cosmological observations have indicated the presence of DM [1]. Within the paradigm of the standard model of cosmology (ΛCDM) recent measurements of the Cosmic Microwave Background Radiation (CMBR) estimated that about 26% of the energy budget of our Universe consists of DM [2, 3]. 1 CMBR, together with Big Bang Nucleosynthesis (BBN) requires DM to be non-baryonic. Astro-physical objects, especially primordial black holes (PBHs) have been considered as DM candidates. While such PBHs, for certain windows of mass 2 can account for the entire energy budget of DM, it has been shown that adequate production of PBHs after (single-field slow-roll) inflation can be difficult [7,8]. However, the standard model (SM) of particle physics, does not incorporate any suitable DM candidate. Various extensions of the SM has been considered in the literature [9,10]. A generic aspect in DM models concerns about the stability of DM. Constraints from structure formation, indirect searches [11][12][13] and CMB [14] require DM to be very long-lived (life-time τ 10 26 s depending on the decay modes). The simplest models introduce a global symmetry to prevent the decay of DM. However, it has been argued that such global symmetries may be broken due to gravitational...

Multi-scalar signature of self-interacting dark matter in the NMSSM and beyond

“…short lifetime of the scalar. And the simplest solution is to introduce new particles and interactions [22,36,39] such that the scalar mediator can decay almost promptly through new channels.…”

“…The DM splitting (χ → φχ) becomes also significant in this case. A generic issue of SIDM scenario with simple DM sector is the tension between Big Bang Nucleosynthesis (BBN) limits and dark matter direct detection constraints [22,[36][37][38][39]. Possible solutions require extended particle content and couplings.…”

Dedicated triggers for displaced jets using timing information from electromagnetic calorimeter at HL-LHC

“…Several phenomenological studies explore the possibilities of LLP searches covering a wide range of models and signatures, such as those in refs. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. Collaborations of two major general purpose detectors at LHC, CMS and ATLAS, have also been actively performing several BSM studies involving various LLP signatures.…”

Strong dark matter self-interaction from a stable scalar mediator

“…On the other hand, in the model with a scalar mediator, even though the DM indirect detection constraints can be avoided since the fermionic DM annihilation is p-wave dominated [54], the DM direct detection upper bounds [55] imply the longevity of the scalar mediator, which would modify the primordial abundances of light elements during Big-Bang nucleosynthesis (BBN) [56][57][58]. Though, there have already been many possible solutions proposed to avoid such tensions for models with scalar and vector mediators [54,[59][60][61][62][63][64][65][66][67][68][69].…”