116994417
Measurement of $\eta^\prime\rightarrow \pi^+\pi^- e^+e^-$ and $\eta^\prime\rightarrow \pi^+\pi^-\mu^+\mu^-$
Based on a sample of 225.3 million J/\psi events accumulated with the BESIII detector at the BEPCII, the decays of \eta' to pi+pi-l+l- are studied via J/\psi to \gamma\eta'. A clear \eta' signal is observed in the pi+pi-e+e- mass spectrum, and the branching fraction is measured to be \BR(\eta' to pi+pi-e+e-) = (2.11\pm0.12 (stat.)\pm0.15 (syst.))\times10^{-3}, which is in good agreement with theoretical predictions and the previous measurement, but is determined with much higher precision. No \eta' signal is found in the pi+ pi- mu+ mu- mass spectrum, and the upper limit is determined to be \BR(\eta' to pi+ pi- mu+ mu-)<2.9\times10^{-5} at the 90% confidence level.
125685455
First observation of J / psi and psi(2S) decaying to n K0(S) anti-Lambda + c.c
120632182
Direct measurements of the branching fractions for inclusive K± and inclusive semileptonic decays of D+ and D0 mesons
Abstract With singly-tagged D ¯ samples selected from the data collected at and around 3.773 GeV with the BESII detector at the BEPC collider, we have measured the branching fractions for the inclusive K ± decays of D + and D 0 mesons, which are BF ( D + → K − X ) = ( 24.7 ± 1.3 ± 1.2 ) % , BF ( D + → K + X ) = ( 6.1 ± 0.9 ± 0.4 ) % , BF ( D 0 → K − X ) = ( 57.8 ± 1.6 ± 3.2 ) % and BF ( D 0 → K + X ) = ( 3.5 ± 0.7 ± 0.3 ) % , respectively. We have also measured the branching fractions for the inclusive semileptonic decays of D + and D 0 mesons to be BF ( D + → e + X ) = ( 15.2 ± 0.9 ± 0.8 ) % and BF ( D 0 → e + X ) = ( 6.3 ± 0.7 ± 0.4 ) % . These yield the ratio of their partial widths to be Γ ( D + → e + X ) / Γ ( D 0 → e + X ) = 0.95 ± 0.12 ± 0.07 .
124457067
Search for Invisible Decays of eta and eta-prime in the Processes J/psi ---> phi eta and phi eta-prime
Using a data sample of 58x10{sup 6} J/{psi} decays collected with the Beijing Spectrometer II detector at the Beijing Electron Positron Collider, searches for invisible decays of {eta} and {eta}{sup '} in J/{psi} to {phi}{eta} and {phi}{eta}{sup '} are performed. The {phi} signals, which are reconstructed in K{sup +}K{sup -} final states, are used to tag the {eta} and {eta}{sup '} decays. No signals are found for the invisible decays of either {eta} or {eta}{sup '}, and upper limits at the 90% confidence level are determined to be 1.65x10{sup -3} for the ratio (B({eta}{yields}invisible)/B({eta}{yields}{gamma}{gamma})) and 6.69x10{sup -2} for (B({eta}{sup '}{yields}invisible)/B({eta}{sup '}{yields}{gamma}{gamma})). These are the first searches for {eta} and {eta}{sup '} decays into invisible final states.
209856078
Measurement of the Matrix Element for the Decay $\eta^{\prime} \to \eta \pi^+\pi^-$
110632418
The BABAR detector: Upgrades, operation and performance
The BaBar detector operated successfully at the PEP-II asymmetric e +e- collider at the SLAC National Accelerator Laboratory from 1999 to 2008. This report covers upgrades, operation, and performance of the collider and the detector systems, as well as the trigger, online and offline computing, and aspects of event reconstruction since the beginning of data taking.
119285874
Separable and non-separable multi-field inflation and large non-Gaussianity
In this paper we provide a general framework based on $\delta N$ formalism to estimate the cosmological observables pertaining to the cosmic microwave background radiation for non-separable potentials, and for generic \emph{end of inflation} boundary conditions. We provide analytical and numerical solutions to the relevant observables by decomposing the cosmological perturbations along the curvature and the isocurvature directions, \emph{instead of adiabatic and entropy directions}. We then study under what conditions large bi-spectrum and tri-spectrum can be generated through phase transition which ends inflation. In an illustrative example, we show that large $f_{NL}\sim {\cal O}(80)$ and $\tau_{NL}\sim {\cal O}(20000)$ can be obtained for the case of separable and non-separable inflationary potentials.
73712405
Decaying dark matter in supersymmetric SU(5) models
Abstract Motivated by recent observations from PAMELA, Fermi and H.E.S.S., we consider dark matter decays in the framework of supersymmetric SU(5) grand unification theories. An SU(5) singlet S is assumed to be the main component of dark matters, which decays into visible particles through dimension six operators suppressed by the grand unification scale. Under certain conditions, S decays dominantly into a pair of sleptons with universal coupling for all generations. Subsequently, electrons and positrons are produced from cascade decays of these sleptons. These cascade decay chains smooth the e + + e − spectrum, which permit naturally a good fit to the Fermi-LAT data. The observed positron fraction upturn by PAMELA can be reproduced simultaneously. We have also calculated diffuse gamma-ray spectra due to the e ± excesses and compared them with the preliminary Fermi-LAT data from 0.1 GeV to 10 GeV in the region 0 ° ⩽ l ⩽ 360 ° , 10 ° ⩽ | b | ⩽ 20 ° . The photon spectrum of energy above 100 GeV, mainly from final state radiations, may be checked in the near future.
119257125
Higgs boson decays and production via gluon fusion at LHC in littlest Higgs models with T-parity
We study the Higgs boson decays and production via gluon fusion at the LHC as a probe of two typical littlest Higgs models which introduce a top quark partner with different (even and odd) T parity to cancel the Higgs mass quadratic divergence contributed by the top quark. For each model, we consider two different choices for the down-type quark Yukawa couplings. We first examine the branching ratios of the Higgs boson decays and then study the production via gluon fusion followed by the decay into two photons or two weak gauge bosons. We find that the predictions can be quite different for different models or different choices of down-type quark Yukawa couplings, and all these predictions can sizably deviate from the standard model predictions. So the Higgs boson processes at the LHC can be a sensitive probe for these littlest Higgs models.
119223074
Visible sector inflation and the right thermal history in light of Planck data
Inflation creates perturbations for the large scale structures in the universe, but it also dilutes everything. Therefore it is pertinent that the end of inflation must explain how to excite the Standard Model dof along with the dark matter. In this paper we will briefly discuss the role of visible sector inflaton candidates which are embedded within the Minimal Supersymmetric Standard Model (MSSM) and discuss their merit on how well they match the current data from the Planck. Since the inflaton carries the Standard Model charges their decay naturally produces all the relevant dof with no dark/hidden sector radiation and no isocurvature fluctuations. We will first discuss a single supersymmetric flat direction model of inflation and demonstrate what parameter space is allowed by the Planck and the LHC. We will also consider where the perturbations are created by another light field which decays after inflation, known as a curvaton. The late decay of the curvaton can create observable non-Gaussianity. In the end we will discuss the role of a spectator field whose origin may not lie within the visible sector physics, but its sheer presence during inflation can still create all the perturbations responsible for the large scale structures including possible non-Gaussianity, while the inflaton is embedded within the visible sector which creates all the relevant matter including dark matter, but no dark radiation.
119173786
Higgs-pair production in littlest Higgs model with T parity
The Higgs-pair production process at the CERN Large Hadron Collider, which will provide a way to test the Higgs boson self-coupling, may be sensitive to new physics. In the framework of the littlest Higgs model with T parity, such Higgs-pair production can proceed through additional loop diagrams, and thus the production rate can be quite different from the standard model prediction. Our calculations show that, due to the loop contributions of both T-even and T-odd quarks predicted in this model, the production rate can be significantly enhanced relative to the standard model prediction and also can be larger than the production rate in the minimal supersymmetric model. Also, we find that the T-odd quark contributions, which were not included in a previous study, are equally important compared with the T-even quark contributions.