Beam Dump Experiment at Future Electron-Positron Colliders

We propose a new beam dump experiment at future colliders with electron ($e^-$) and positron ($e^+$) beams, BDee, which will provide a new possibility to search for hidden particles, like hidden photon. If a particle detector is installed behind the beam dump, it can detect the signal of in-flight decay of the hidden particles produced by the scatterings of $e^\pm$ beams off materials for dumping. We show that, compared to past experiments, BDee (in particular BDee at $e^+e^-$ linear collider) significantly enlarges the parameter region where the signal of the hidden particle can be discovered.Comment: 4 pages, 2 figure

Improved jet clustering algorithm with vertex information for multi-bottom final states

In collider physics at the TeV scale, there are many important processes which involve six or more jets. The sensitivity of the physics analysis depends critically on the performance of the jet clustering algorithm. We present a full detector simulation study for the ILC of our new algorithm which makes use of secondary vertices which improves the reconstruction of b jets. This algorithm will have many useful applications, such as in measurements involving a light Higgs which decays predominantly into two b quarks. We focus on the measurement of the Higgs self-coupling, which has so far proven to be challenging but is one of the most important measurements at the ILC.Comment: 7 pages, 3 figures, Proc. TIPP 201

A study of the measurement precision of the Higgs boson decaying into tau pairs at the ILC

We evaluate the measurement precision of the production cross section times the branching ratio of the Higgs boson decaying into tau lepton pairs at the International Linear Collider (ILC). We analyze various final states associated with the main production mechanisms of the Higgs boson, the Higgs-strahlung and WW-fusion processes. The statistical precision of the production cross section times the branching ratio is estimated to be 2.6% and 6.9% for the Higgs-strahlung andWW-fusion processes, respectively, with the nominal integrated luminosities assumed in the ILC Technical Design Report; the precision improves to 1.0% and 3.4% with the running scenario including possible luminosity upgrades. The study provides a reference performance of the ILC for future phenomenological analyses.Comment: 10 pages, 6 figures, 9 tables, revised from v

TROPHODYNAMIC ACCUMULATION OF BROMINATED FLAME RETARDANTS IN BIOTA OF JAKARTA BAY

The level of contamination, bioaccumulation and potential trophic transfer of toxic pollutants known as brominated flame retardants (BFRs), such as polybrominated diphenyl ethers (PBDEs) and hexabromocychlododecanes (HBCDs), was examined in biota representing different trophic levels in Jakarta Bay. Various organisms were collected using several catching methods during July-August 2007 at eastern part of the bay and were analyzed for nitrogen (N) and carbon (C) stable isotopes, 14 PBDE congeners and three HBCD isomers using GC-C-IRMS, GC-MS and LC-MS/MS, respectively. Analysis of N and C indicated that the biota was composed by different trophic levels within the Jakarta Bay ecosystem. Concentrations of total PBDEs and total HBCDs varied according to species, ranged from 1.6 ng/g lipid wt. to 57 ng/g lipid wt. and below detection limit (nd) to 4.1 ng/g lipid wt, respectively. Furthermore, there was significant positive correlation between trophic level (TL) and concentration of PBDEs was found, but not HBCDs. Trophic Magnification Factors (TMF) values of PBDEs ranged 0.63–3.0 with only two congeners (BDE-47 and BDE–100) having TMFs greater than one

Electroweakino Searches: A Comparative Study for LHC and ILC (A Snowmass White Paper)

We make a systematic and comparative study for the LHC and ILC for the electroweakino searches in the Minimal Supersymmetric Standard Model. We adopt a general bottom-up approach and scan over the parameter regions for all the three cases of the lightest supersymmetric particle being Bino-, Wino-, and Higgsino-like. The electroweakino signal from pair production and subsequent decay to Wh (h to b\bar b) final state may yield a sensitivity of 95% C.L. exclusion (5sigma discovery) to the mass scale M_2, mu ~ 250-400 GeV (200-250 GeV) at the 14 TeV LHC with an luminosity of 300 fb^{-1}. Combining with all the other decay channels, the 95% C.L. exclusion (5sigma discovery) may be extended to M_2, mu ~ 480-700 GeV (320-500 GeV). At the ILC, the electroweakinos could be readily discovered once the kinematical threshold is crossed, and their properties could be thoroughly studied.Comment: 12 pages, 3 figure

Naturalness and light Higgsinos: why ILC is the right machine for SUSY discovery

Radiatively-driven natural supersymmetry, a theoretically and experimentally well-motivated framework, centers around the predicted existence of four light, nearly mass-degenerate Higgsinos with mass $\sim 100-200$ GeV (not too far above $m_Z$). The small mass splittings amongst the higgsinos, typically 4-20 GeV, results in very little visible energy arising from decays of the heavier higgsinos. Given that other SUSY particles are considerably heavy, this makes detection challenging at hadron colliders. On the other hand, the clean environment of an electron-positron collider with $\sqrt{s}>2m_{higgsino}$ would enable a decisive search of these required higgsinos, and thus either the discovery or exclusion of natural SUSY. We present a detailed simulation study of precision measurements of higgsino masses and production cross sections at $\sqrt{s}$ = 500 GeV of the proposed International Linear Collider currently under consideration for construction in Japan. The study is based on a Geant4 simulation of the International Large Detector concept. We examine several benchmark points just beyond the HL-LHC reach, with four light higgsinos directly accessible by the ILC, and the mass differences between the lightest SUSY particle and the heavier states ranging from about 4 to 20 GeV. It can be shown that their masses and production cross sections can be precisely measured to approximately 1\% precision or better. These precise measurements allow for extracting the underlying weak scale SUSY parameters, giving predictions for the masses of heavier SUSY states. These provide motivation for future high-energy colliders. Additionally, dark matter properties may be derived. Evolution of the measured gaugino masses to high energies should allow testing the hypothesis of gaugino mass unification.Comment: 6 pages, 4 figures; to appear in the proceedings for EPS-HEP2017, 5-12 July 2017, Venice, Ital

Physics Case for the ILC Project: Perspective from Beyond the Standard Model

The International Linear Collider (ILC) has recently proven its technical maturity with the publication of a Technical Design Report, and there is a strong interest in Japan to host such a machine. We summarize key aspects of the Beyond the Standard Model physics case for the ILC in this contribution to the US High Energy Physics strategy process. On top of the strong guaranteed physics case in the detailed exploration of the recently discovered Higgs boson, the top quark and electroweak precision measurements, the ILC will offer unique opportunities which are complementary to the LHC program of the next decade. Many of these opportunities have connections to the Cosmic and Intensity Frontiers, which we comment on in detail. We illustrate the general picture with examples of how our world could turn out to be and what the ILC would contribute in these cases, with an emphasis on value-added beyond the LHC. These comprise examples from Supersymmetry including light Higgsinos, a comprehensive bottom-up coverage of NLSP-LSP combinations for slepton, squark, chargino and neutralino NLSP, a stau-coannihilation dark matter scenario and bilinear R-parity violation as explanation for neutrino masses and mixing, as well as generic WIMP searches and Little Higgs models as non-SUSY examples.Comment: 20 pages, 10 figures. Contributed to Snowmass Community Summer Study 201