6,133 research outputs found

    GeV Scale Asymmetric Dark Matter from Mirror Universe: Direct Detection and LHC Signatures

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    Mirror universe is a fundamental way to restore parity symmetry in weak interactions. It naturally provides the lightest mirror nucleon as a unique GeV-scale asymmetric dark matter particle candidate. We conjecture that the mirror parity is respected by the fundamental interaction Lagrangian, and its possible soft breaking arises only from non-interaction terms in the gauge-singlet sector. We realize the spontaneous mirror parity violation by minimizing the vacuum Higgs potential, and derive the corresponding Higgs spectrum. We demonstrate that the common origin of CP violation in the visible and mirror neutrino seesaws can generate the right amount of matter and mirror dark matter via leptogenesis. We analyze the direct detections of GeV-scale mirror dark matter by TEXONO and CDEX experiments. We further study the predicted distinctive Higgs signatures at the LHC.Comment: 16pp. Plenary talk presented by HJH at the International Symposium on Cosmology and Particle Astrophysics (CosPA2011). To appear in the conference proceedings of IJMP. Minor refinement

    Interplay between multi-spin and chiral spin interactions on triangular lattice

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    We investigate the spin-12\frac{1}{2} nearest-neighber Heisenberg model with the four-site ring-exchange J4J_4 and chiral interaction JχJ_\chi on the triangular lattice by using the variational Monte Carlo method. The J4J_4 term induces the quadratic band touching (QBT) quantum spin liquid (QSL) with only a d+idd+id spinon pairing (without hopping term), the nodal dd-wave QSL and U(1) QSL with a finite spinon Fermi surface progressively. The effect of the chiral interaction JχJ_\chi can enrich the phase diagram with two interesting chiral QSLs (topological orders) with the same quantized Chern number C=12\mathcal{C} = \frac{1}{2} and ground-state degeneracy GSD = 2, namely the U(1) chiral spin liquid (CSL) and Z2_2 d+idd+id-wave QSL. The nodal dd-wave QSL is fragile and will turn to the Z2_2 d+idd+id QSL with any finite JχJ_\chi within our numerical calculation. However, in the process from QBT to the Z2_2 d+idd+id QSL with the increase of JχJ_\chi, an exotic crossover region is found. In this region, the previous QBT state acquires a small hopping term so that it opens a small gap at the otherwise band touching points, and leads to an energy minimum which is energetically more favorable compared to another competitive local minimum from the Z2_2 d+idd+id QSL. We dub this state as the proximate QBT QSL and it gives way to the Z2_2 d+idd+id QSL eventually. Therefore, the cooperation of the J4J_4 and JχJ_\chi terms favors mostly the Z2_2 d+idd+id-wave QSL, so that this phase occupies the largest region in the phase diagram

    A double neutron star merger origin for the cosmological relativistic fading source PTF11agg?

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    The Palomar Transient Factory (PTF) team recently reported the discovery of a rapidly fading optical transient source, PTF11agg. A long-lived scintillating radio counterpart was identified, but the search for a high energy counterpart showed negative results. The PTF team speculated that PTF11agg may represent a new class of relativistic outbursts. Here we suggest that a neutron star (NS)-NS merger system with a supra-massive magnetar central engine could be a possible source to power such a transient, if our line of sight is not on the jet axis direction of the system. These systems are also top candidates for gravitational wave sources to be detected in the advanced LIGO/Virgo era. We find that the PTF11agg data could be explained well with such a model, suggesting that at least some gravitational wave bursts due to NS-NS mergers may be associated with such a bright electromagnetic counterpart without a \gamma-ray trigger.Comment: Accepted for publication in ApJ Letter
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