Isospin violating dark matter in Stückelberg portal scenarios

It was recently pointed out that direct detection signals from at least three different targets may be used to determine whether the Dark Matter (DM) particle is different from its antiparticle. In this work, we examine in detail the feasibility of this test under different conditions, motivated by proposals for future detectors. Specifically, we perform likelihood fits to mock data under the hypotheses that the DM particle is identical to or different from its antiparticle, and determine the significance with which the former can be rejected in favor of the latter. In our analysis, we consider 3 different values of the DM mass (50 GeV, 300 GeV, 1 TeV) and 4 different experimental ensembles, each consisting of at least 3 different targets -Xe and Ar plus one among the following: Si, Ge, CaWO 4 , or Ge/CaWO 4 . For each of these experimental ensembles and each DM mass, the expected discrimination significance is calculated as a function of the DM-nucleon couplings. In the best case scenario, the discrimination significance can exceed O(3σ) for three of the four ensembles considered, reaching O(5σ) at special values of the DM-nucleon couplings. For the ensemble including Si, O(5σ) significance can be achieved for a range of DM masses and over a much wider range of DM-nucleon couplings, highlighting the need for a variety of experimental targets in order to determine the DM properties. These results show that future direct detection signals could be used to exclude, at a statistically significant level, a Majorana or a real DM particle, giving a critical clue about the identity of the Dark Matter.

Section: Discussionmentioning

confidence: 96%

Prospects for determining the particle/antiparticle nature of WIMP dark matter with direct detection experiments

Kavanagh

Queiroz

Rodejohann

et al. 2017

“…In many ISV studies [55][56][57][58][59][60][61][62][63][64][65][66], the ISV coupling ratio for maximum cancellation between the DM-proton contribution and the DM-neutron contribution is defined at the amplitude level. Unlike such traditional definitions, we define our ISV coupling ratio for maximum cancellation at the event rate level, in which we take the experimental efficiencies and the DM velocity distribution into account.…”

Section: Numerical Resultsmentioning

confidence: 99%

A combined analysis of PandaX, LUX, and XENON1T experiments within the framework of dark matter effective theory

Liu¹,

Su²,

Tsai³

et al. 2017

Weakly interacting massive particles are a widely well-probed dark matter candidate by the dark matter direct detection experiments. Theoretically, there are a large number of ultraviolet completed models that consist of a weakly interacting massive particle dark matter. The variety of models makes the comparison with the direct detection data complicated and often non-trivial. To overcome this, in the non-relativistic limit, the effective theory was developed in the literature which works very well to significantly reduce the complexity of dark matter-nucleon interactions and to better study the nuclear response functions. In the effective theory framework for a spin-1/2 dark matter, we combine three independent likelihood functions from the latest PandaX, LUX, and XENON1T data, and give a joint limit on each effective coupling. The astrophysical uncertainties of the dark matter distribution are also included in the likelihood. We further discuss the isospin violating cases of the interactions. Finally, for both dimension-five and dimension-six effective theories above the electroweak scale, we give updated limits of the new physics mass scales.

“…However it was shown in ref. [41] that Z s lighter than the maximum bound value for the mass of 3 TeV could evade those searches by a reduction of their couplings. So it could be that in the forthcoming LHC run such Z's in the 1.5-5 TeV region could be produced.…”

Section: )mentioning

confidence: 99%

A megaxion at 750 GeV as a first hint of low scale string theory

Ibáñez

Lozano

2016

Journal of High Energy Physics 2016.7 (2016): 021 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA)Low scale string models naturally have axion-like pseudoscalars which couple directly to gluons and photons (but not W’s) at tree level. We show how they typically get tree level masses in the presence of closed string fluxes, consistent with the axion discrete gauge symmetry, in a way akin of the axion monodromy of string inflation and relaxion models. We discuss the possibility that the hints for a resonance at 750 GeV recently reported at ATLAS and CMS could correspond to such a heavy axion state (megaxion). Adjusting the production rate and branching ratios suggest the string scale to be of order Ms ≈ 7–104 TeV, depending on the compactification geometry. If this interpretation was correct, one extra Z’ gauge boson could be produced before reaching the string threshold at LHC and future collidersThis work is partially supported by the grants FPA2012-32828 and FPA2015-65929-P from the MINECO, the ERC Advanced Grant SPLE under contract ERC-2012-ADG-20120216-320421, the Consolider-Ingenio 2010 programme under grant MULTIDARK CSD2009-00064 and the grant SEV-2012-0249 of the “Centro de Excelencia Severo Ochoa” Programm