Towards LHC Physics with Non-local Standard Model

We take a few steps towards constructing a string-inspired nonlocal extension of the Standard Model. We start by illustrating how quantum loop calculations can be performed in nonlocal scalar field theory. In particular, we show the potential to address the hierarchy problem in the nonlocal framework. Next, we construct a nonlocal abelian gauge model and derive modifications of the gauge interaction vertex and field propagators. We apply the modifications to a toy version of the nonlocal Standard Model and investigate collider phenomenology. We find the lower bound on the scale of non-locality from the 8 TeV LHC data to be $2.5-3$ TeV.Comment: Changes made to be consistent with the journal versio

SU(5)×\timesU(1)X_X grand unification with minimal seesaw and Z′Z^\prime-portal dark matter

We propose a grand unified SU(5)$\times$U(1)$_X$ model, where the standard SU(5) grand unified theory is supplemented by minimal seesaw and a right-handed neutrino dark matter with an introduction of a global $Z_2$-parity. In the presence of three right-handed neutrinos (RHNs), the model is free from all gauge and mixed-gravitational anomalies. The SU(5) symmetry is broken into the Standard Model (SM) gauge group at $M_{\rm GUT} \simeq 4 \times 10^{16}$ GeV in the standard manner, while the U(1)$_X$ symmetry breaking occurs at the TeV scale, which generates the TeV-scale mass of the U(1)$_X$ gauge boson ($Z^\prime$ boson) and the three Majorana RHNs. A unique $Z_2$-odd RHN is stable and serves as the dark matter (DM) in the present Universe, while the remaining two RHNs work to generate the SM neutrino masses through the minimal seesaw. We investigate the $Z^\prime$-portal RHN DM scenario in this model context, and find that the constraints from the DM relic abundance and the search results for a $Z^\prime$ boson resonance at the Large Hadron Collider (LHC) are complementary to narrow down the allowed parameter region, which will be fully covered by the future LHC experiments (for the $Z^\prime$ boson mass $<$ 5 TeV). We also briefly discuss the successful implementation of Baryogenesis and cosmological inflation scenarios in the present model.Comment: 6 pages, 2 figures, revised plots, accepted for publication in pl

Natural mu-term generation in supergravity scenario

We discuss a natural way to generate the mu-term in supergravity scenario. Once the supergravity effects are taken into account, the vacuum expectation values (VEVs) of the heavy fields are in general shifted from the values in the supersymmetric limit. We note that this fact is independent of any Kahler ansatz and the values of the VEV shifts are of the order of the gravitino mass. As an example, an explicit model is presented, in which both of the mu-term and the B-term of the electroweak scale are generated by the VEV shifts through the supergravity effects. This model is a kind of the next to minimal supersymmetric standard model, but there is no light standard model singlet field. Also, we emphasize that our discussion can be naturally applied to the supersymmetric grand unified theory.Comment: 9 page

Gravity Waves and Gravitino Dark Matter in μ\mu-Hybrid Inflation

We propose a novel reformulation of supersymmetric (more precisely $\mu$-) hybrid inflation based on a local U(1) or any suitable extension of the minimal supersymmetric standard model (MSSM) which also resolves the $\mu$ problem. We employ a suitable Kahler potential which effectively yields quartic inflation with non-minimal coupling to gravity. Imposing the gravitino Big Bang Nucleosynthesis (BBN) constraint on the reheat temperature ($T_r \lesssim 10^6$ GeV) and requiring a neutralino LSP, the tensor to scalar ratio ($r$) has a lower bound $r \gtrsim 0.004$. The U(1) symmetry breaking scale lies between $10^8$ and $10^{12}$ GeV. We also discuss a scenario with gravitino dark matter whose mass is a few GeV.Comment: 5 pages, 4 figures, revised version to appear in Physics Letters