Expression of interest to the Superconducting Super Collider Laboratory by the L* Collaboration

title: Improved calculation of the energy release in neutron-induced fission
abstract: Fission energy is one of the basic parameters needed in the calculation of antineutrino ux from nuclear reactors. Improving the precision of ssion energy calculations is useful for current and future reactor neutrino experiments, which are aimed at more precise determinations of neutrino oscillation parameters. In this article, we give new values for ssion energies of some common thermal reactor fuel isotopes, with improvements on three aspects. One is more recent input data acquired from updated nuclear databases. The second improvement is a consideration of the production yields of ssion fragments from both thermal and fast incident neutrons for each of the four main fuel isotopes. The third improvement is a more careful calculation of the average energy taken away by antineutrinos in thermal ssion involving a comparison of antineutrino spectra from dierent models. The change in calculated antineutrino ux due to the new values of ssion energy is about 0.32%, and the uncertainties of the new values are about 50% smaller.

title: Leakage tests of the stainless steel vessels of the antineutrino detectors in the Daya Bay reactor neutrino experiment
abstract: The antineutrino detectors for the Daya Bay reactor neutrino experiment are liquid scintillator detectors designed to detect electron anti-neutrino via inverse beta interactions with high efficiency and low backgrounds. Since the antineutrino detector will be installed and immerged in water Cherenkov detector and will run for 3 to 5 years, water tightness is critical to the successful operation of the antineutrino detectors. A special seal technique was used for this purpose. Three leak checking methods have been employed to ensure the seal quality. This paper describes the sealing method and leakage testing results.

title: Gamma-rays from nearby clusters: Constraints on selected decaying dark matter models
abstract: Recently, the Fermi-LAT Collaboration reported upper limits on the GeV gamma-ray flux from nearby clusters of galaxies. Motivated by these limits, we study corresponding constraints on gamma-ray emissions from two specific decaying dark matter models, one via grand unification scale suppressed operators and the other via R-parity violating operators. Both can account for the PAMELA and Fermi-LAT excesses of e ± . For GUT decaying dark matter, the gamma-rays from the M49 and Fornax clusters, with energy in the range of 1 to 10 GeV, lead to the most stringent constraints to date. As a result, this dark matter is disfavored with conventional model of e ± background. In addition, it is likely that some tension exists between the Fermi-LAT e ± excess and the gamma-ray constraints for any decaying dark matter model, provided conventional model of e ± background is adopted. Nevertheless, the GUT decaying dark matter can still solely account for the PAMELA positron fraction excess without violating the gamma-ray constraints. For the gravitino dark matter model with R-parity violation, cluster observations do not give tight constraints. This is because a different e ± background has been adopted which leads to relatively light dark matter mass around 200 GeV.

title: Two Higgs bidoublet model with spontaneous P and CP violation and decoupling limit to the two Higgs doublet model
abstract: The two Higgs bidoublet left-right symmetric model (2HBDM) as a simple extension of the minimal left-right symmetric model with a single Higgs bidoublet is motivated to realize both spontaneous parity (P) violation and charge conjugation and parity (CP) violation while consistent with the low-energy phenomenology without significant fine-tuning. By carefully investigating the Higgs potential of the model, we find that sizable CP-violating phases are allowed after the spontaneous symmetry breaking. The mass spectra of the extra scalars in the 2HBDM are significantly different from the ones in the minimal left-right symmetric model. In particular, we demonstrate in the decoupling limit when the right-handed gauge-symmetry-breaking scale is much higher than the electroweak scale, the 2HBDM decouples into the general two Higgs doublet model with spontaneous CP violation and has rich induced sources of CP violation. We show that in the decoupling limit, it contains extra light Higgs bosons with masses around electroweak scale, which can be directly searched at the ongoing LHC and future International Linear Collider experiments.

title: Nonlinear realization of spontaneously broken N = 1 supersymmetry revisited
abstract: This paper revisits the nonlinear realization of spontaneously broken N = 1 supersymmetry. It is shown that the constrained superfield formalism as proposed in  can be reinterpreted in the language of standard realization of nonlinear supersymmetry via a new and simpler route. Explicit formulas of actions are presented for general renormalizable theories with or without gauge interactions. The nonlinearWess-Zumino gauge is discussed and relations are pointed out for different definitions of gauge fields. In addition, a general procedure is provided to deal with theories of arbitrary Kahler potentials.

title: Higgs boson production in photon-photon collision at ILC: a comparative study in different little Higgs models
abstract: We study the process $ \gamma \gamma \to h \to b\bar b $ at ILC as a probe of different little Higgs models, including the simplest little Higgs model (SLH), the littlest Higgs model (LH), and two types of littlest Higgs models with T-parity (LHT-I, LHT-II). Compared with the Standard Model (SM) prediction, the production rate is found to be sizably altered in these little Higgs models and, more interestingly, different models give different predictions. We find that the production rate can be possibly enhanced only in the LHT-II for some part of the parameter space, while in all other cases the rate is suppressed. The suppression can be 10% in the LH and as much as 60% in both the SLH and the LHT-I/LHT-II. The severe suppression in the SLH happens for a large tan β and a small mh, in which the new decay mode h → ηη (η is a light pseudo-scalar) is dominant; while for the LHT-I/LHT-II the large suppression occurs when f and mh are both small so that the new decay mode h → AHAH is dominant. Therefore, the precision measurement of such a production process at the ILC will allow for a test of these models and even distinguish between different scenarios.