EXPERIMENTAL STUDY OF J/PSI RADIATIVE DECAY TO PI 0PI 0

title: Spectral measurement of electron antineutrino oscillation amplitude and frequency at Daya Bay.
abstract: A measurement of the energy dependence of antineutrino disappearance at the Daya Bay reactor neutrino experiment is reported. Electron antineutrinos (ν¯(e)) from six 2.9  GW(th) reactors were detected with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls. Using 217 days of data, 41 589 (203 809 and 92 912) antineutrino candidates were detected in the far hall (near halls). An improved measurement of the oscillation amplitude sin(2)2θ(13)=0.090(-0.009)(+0.008) and the first direct measurement of the ν¯(e) mass-squared difference |Δm(ee)2|=(2.59(-0.20)(+0.19))×10(-3)  eV2 is obtained using the observed ν¯(e) rates and energy spectra in a three-neutrino framework. This value of |Δm(ee)2| is consistent with |Δm(μμ)2| measured by muon neutrino disappearance, supporting the three-flavor oscillation model.

title: Experimental study of f0(975) in J / psi decays

title: Measurements of $\psi^\prime \to \bar{p} K^+ \Sigma^0$ and $\chi_{cj} \to \bar{p} K^+ \Lambda$
abstract: Using a sample of 1.06 x 10(8) psi' mesons collectedwith the BESIII detector at the BEPCII e(+)e(-) collider and chi(cJ) mesons produced via radiative transitions from the psi', we report the first observation for psi' -> (p) over barK(+)Sigma(0) + c.c. (charge conjugate), as well as improved measurements for the chi(cJ) hyperon decays chi(cJ) -> (p) over barK(+) Lambda + c.c. The branching fractions are measured to be B(psi' -> (p) over barK(+) Sigma(0) + c.c) = (1.67 +/- 0.13 +/- 0.12) x 10(-5), B(chi(c0) -> (p) over barK(+) Lambda + c.c) = (13.2 +/- 0.3 +/- 1.0) x 10(-4), B(chi(c1) -> (p) over barK(+) Lambda + c.c) = (4.5 +/- 0.2 +/- 0.4) x 10(-4), and B(chi(c2) -> (p) over barK(+) Lambda + c.c) = (8.4 +/- 0.3 +/- 0.6) x 10(-4), where the first error is statistical, and the second is systematic. In the decay of chi(c0) -> (p) over barK(+) Lambda + c.c:, an anomalous enhancement near threshold is observed in the invariant mass distribution of (p) over bar Lambda + c.c:, which cannot be explained by phase space.

title: Search for a light sterile neutrino at Daya Bay.
abstract: A search for light sterile neutrino mixing was performed with the first 217 days of data from the Daya Bay Reactor Antineutrino Experiment. The experiment's unique configuration of multiple baselines from six 2.9 GW(th) nuclear reactors to six antineutrino detectors deployed in two near (effective baselines 512 m and 561 m) and one far (1579 m) underground experimental halls makes it possible to test for oscillations to a fourth (sterile) neutrino in the 10(-3) eV(2)<|Δm(41)(2) |< 0.3 eV(2) range. The relative spectral distortion due to the disappearance of electron antineutrinos was found to be consistent with that of the three-flavor oscillation model. The derived limits on sin(2) 2θ(14) cover the 10(-3) eV(2) ≲ |Δm(41)(2)| ≲ 0.1 eV(2) region, which was largely unexplored.

title: Study of $J/ψ → ωp\overline{p}$ at BESIII

title: LHC diphoton Higgs signal and top quark forward-backward asymmetry in quasi-inert Higgs doublet model
abstract: A bstractIn the quasi-inert Higgs doublet model, we study the LHC diphoton rate for a standard model-like Higgs boson and the top quark forward-backward asymmetry at Tevatron. Taking into account the constraints from the vacuum stability, unitarity, electroweak precision tests, flavor physics and the related experimental data of top quark, we find that compared with the standard model prediction, the diphoton rate of Higgs boson at LHC can be enhanced due to the light charged Higgs contributions, while the measurement of the top quark forward-backward asymmetry at Tevatron can be explained to within 1σ due to the non-standard model neutral Higgs bosons contributions. Finally, the correlations between the two observables are discussed.

title: Light top squark in precision top quark sample
abstract: The uncertainty of $t\bar{t}$ production cross section measurement at LHC is at a-few-percent level which still allows the stop pair production $\tilde{t}\tilde{t}^{*}$ with identical final states $2b+\ell+nj+{E}_{T}$. In this paper, we attempt to use the existing measurement of $W$-polarization in top quark decay to improve the distinction between stop and top quark states. We apply the ATLAS $\chi^2$ method of $W$-polarization measurement in semi-leptonic $t\bar{t}$ final state to semi-leptonic stop pair samples and study its prediction. We find that the faked top events from stop mostly contribute to the left-handed polarized $W$ due to the reconstruction. The benchmark point with maximal contribution to top events only changes $F_{L}$ by 1%. After comparing with the current experiments, we conclude that the current measurement of $W$-polarization in $t$ decay cannot exclude the light stop scenario.

title: Revisit to non-decoupling MSSM
abstract: Dipole operator s ¯ σ μ ν F μ ν b requires the helicity flip in the involving quark states thus the breaking of chiral U ( 3 ) Q × U ( 3 ) d . On the other hand, the b quark mass generation is also a consequence of chiral U ( 3 ) Q × U ( 3 ) d symmetry breaking. Therefore, in many models, there might be strong correlation between the b → s γ and b quark Yukawa coupling. In this Letter, we use non-decoupling MSSM model to illustrate this feature. In the scenario, the light Higgs boson may evade the direct search experiments at LEPII or Tevatron while the 125 GeV Higgs-like boson is identified as the heavy Higgs boson in the spectrum. A light charged Higgs is close to the heavy Higgs boson which is of 125 GeV and its contribution to b → s γ requires large supersymmetric correction with large PQ and R -symmetry breaking. The large supersymmetric contribution at the same time significantly modifies the b quark Yukawa coupling. With combined flavor constraints B → X s γ and B s → μ + μ − and direct constraints on Higgs properties, we find best fit scenarios with light stop of O ( 500 GeV ) , negative A t around − 750 GeV and large μ -term of 2–3 TeV. In addition, reduction in b b ¯ partial width may also result in large enhancement of ττ decay branching fraction. Large parameter region in the survival space under all bounds may be further constrained by H → τ τ if no excess of ττ is confirmed at LHC. We only identify a small parameter region with significant H → h h decay that is consistent with all bounds and reduced ττ decay branching fraction. In the end, if current dark matter mostly consists of neutralino, direct detection experiments like XENON100 also puts stringent bound over this scenario with light Higgs bosons. The light stops which are required by flavor constraints can further enhance the scattering cross section.

title: Top quark forward-backward asymmetry and charge asymmetry in the left-right twin Higgs model
abstract: In order to explain the Tevatron anomaly of the top quark forward-backward asymmetry A(FB)(t) in the left-right twin Higgs model, we choose to give up the lightest neutral particle of (h) over cap field as a stable dark matter candidate. Then a new Yukawa interaction for (h) over cap is allowed, which can be free from the constraint of same-sign top pair production and contribute sizably to A(FB)(t). Considering the constraints from the production rates of the top pair (t (t) over bar), the top decay rates, and t (t) over bar invariant mass distribution, we find that this model with such new Yukawa interaction can explain A(FB)(t) measured at the Tevatron while satisfying the charge asymmetry A(C)(t) measured at the LHC. Moreover, this model predicts a strong correlation between A(C)(t) at the LHC and A(FB)(t) at the Tevatron, i.e., A(C)(t) increases as A(FB)(t) increases.

title: Bound to bounce: a coupled scalar-tachyon model for a smooth bouncing/cyclic universe
abstract: We introduce a string-inspired model for a bouncing/cyclic universe, utilizing the scalar-tachyon coupling as well as contribution from curvature in a closed universe. The universe undergoes the locked inflation, tachyon matter dominated rolling expansion, turnaround and contraction, as well as the subsequent deflation and "bounce" in each cycle of the cosmological evolution. We perform extensive analytic and numerical studies of the above evolution process. The minimum size of the universe is nonzero for generic initial values. The smooth bounce are made possible because of the negative contribution to effective energy density by the curvature term. No ghosts are ever generated at any point in the entire evolution of the universe, with the Null, Weak, and Dominant Energy Conditions preserved even at the bounce points, contrary to many bounce models previously proposed. And the Strong Energy Condition is satisfied in periods with tachyon matter domination.