118459764
Fermion portal dark matter
A bstractWe study a class of simplified dark matter models in which one dark matter particle couples with a mediator and a Standard Model fermion. In such models, collider and direct detection searches probe complimentary regions of parameter space. For Majorana dark matter, direct detection covers the region near mediator-dark matter degeneracy, while colliders probe regions with a large dark matter and mediator mass splitting. For Dirac and complex dark matter, direct detection is effective for the entire region above the mass threshold, but colliders provide a strong bound for dark matter lighter than a few GeV. We also point out that dedicated searches for signatures with two jets or a monojet not coming from initial state radiation, along missing transverse energy can cover the remaining parameter space for thermal relic dark matter.
119330778
Breaking discrete symmetries in broken gauge theories
We study the spontaneous breaking of discrete symmetries in theories with broken gauge symmetry. The intended application is to CP breaking in theories with gauged flavor symmetries, but the analysis described here is preliminary. We dispense with matter fields and take the gauge theory to be weakly coupled and broken spontaneously by unspecified, short-distance forces. We develop an effective-field-theory description of the resultant low-energy theory, and ask whether this theory by itself can describe the subsequent breaking of discrete symmetries. We conclude that this can happen depending on the parameters of the effective theory, and that the intrinsic violation is naturally of order unity.
120134861
General two Higgs doublet model (2HDM-G) and Large Hadron Collider data
We study the consistency of two Higgs doublet models in light of the new bosonic particle discovery at the LHC. We work within a general setup that we call the 2HDM-X, in which the quarks couple to both scalar doublets with aligned couplings such that flavor-changing neutral currents are absent at tree level. The 2HDM-X encompasses the traditional Type I, Type II, lepton specific, and flipped models, but also provides for more general possibilities. The best fit to the current data with a suppressed tau tau signal and a b bbar signal of Standard Model strength is given by the 2HDM-X with specific parameter choices; however, very good fits are also obtained within the lepton-specific model and a democratic model, the 2HDM-D, in which both the up-type and down-type quarks couple to each doublet with equal strengths. The approach provides a general framework in which to interpret future LHC Higgs data within extensions of the Standard Model with two Higgs doublets.
119286848
Mini little Higgs and dark matter
Abstract We construct a little Higgs model with the most minimal extension of the standard model gauge group by an extra U ( 1 ) gauge symmetry. For specific charge assignments of scalars, an approximate U ( 3 ) global symmetry appears in the cutoff-squared scalar mass terms generated from gauge bosons at one-loop level. Hence, the Higgs boson, identified as a pseudo-Goldstone boson of the broken global symmetry, has its mass radiatively protected up to scales of 5–10 TeV. In this model, a Z 2 symmetry, ensuring the two U ( 1 ) gauge groups to be identical, also makes the extra massive neutral gauge boson stable and a viable dark matter candidate with a promising prospect of direct detection.
117637075
Explorations of SU(3) family gauge symmetry
118985590
SU(3) family gauge symmetry and the axion
We analyze the structure of a recently proposed effective field theory (EFT) for the generation of quark and lepton mass ratios and mixing angles, based on the spontaneous breaking of an SU(3) family gauge symmetry at a high scale F. We classify the Yukawa operators necessary to seed the masses, making use of the continuous global symmetries that they preserve. One global U(1), in addition to baryon number and electroweak hypercharge, remains unbroken after the inclusion of all operators required by standard model fermion phenomenology. An associated vacuum symmetry insures the vanishing of the first-family quark and charged-lepton masses in the absence of the family gauge interaction. If this U(1) symmetry is taken to be exact in the EFT, broken explicitly by only the QCD-induced anomaly, and if the breaking scale F is taken to lie in the range 10{sup 9}-10{sup 12} GeV, then the associated Nambu-Goldstone boson is a potential QCD axion.
73584702
Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at $$\sqrt{s}=8~$$s=8TeV with the ATLAS detector
Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb$${}^{-1}$$-1 of $$\sqrt{s}=8$$s=8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with $$p_{\mathrm {T}}> 120$$pT>120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between $$E_{\mathrm {T}}^{\mathrm {miss}}>150$$ETmiss>150 GeV and $$E_{\mathrm {T}}^{\mathrm {miss}}> 700$$ETmiss>700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presented.
119384648
The Performance of CRTNT Fluorescence Light Detector for Sub-EeV Cosmic Ray Observation
Cosmic Ray Tau Neutrino Telescopes (CRTNT) using for sub-EeV cosmic ray measurement is discussed. Performances of a stereoscope configuration with a tower of those telescopes plus two side-triggers are studied. This is done by using a detailed detector simulation driven by Corsika. Detector aperture as a function of shower energy above 10^17 eV is calculated. Event rate of about 20k per year for the second knee measurement is estimated. Event rate for cross calibration with detectors working on higher energy range is also estimated. Different configurations of the detectors are tried for optimization.