118426546
Transverse-Momentum Resummation for Gauge Boson Pair Production at the Hadron Collider
We perform the transverse-momentum resummation for $W^{+}W^{-}$, $ZZ$, and $W^{\pm}Z$ pair productions at the next-to-next-to-leading logarithmic accuracy using soft-collinear effective theory for $\sqrt{S}=8 \text{TeV}$ and $\sqrt{S}=14 \text{TeV}$ at the LHC, respectively. Especially, this is the first calculation of $W^{\pm}Z$ transverse-momentum resummation. We also include the non-perturbative effects and discussions on the PDF uncertainties. Comparing with the next-to-leading logarithmic results, the next-to-next-to-leading logarithmic resummation can reduce the dependence of the transverse-momentum distribution on the factorization scales significantly. Finally, we find that our numerical results are consistent with data measured by CMS collaboration for the $ZZ$ production, which have been only reported by the LHC experiments for the unfolded transverse-momentum distribution of the gauge boson pair production so far, within theoretical and experimental uncertainties.
119247594
Investigate the interaction between dark matter and dark energy
In this paper we investigate the interaction between dark matter and dark energy by considering two different interacting scenarios, i.e. the cases of constant interaction function and variable interaction function. By fitting the current observational data to constrain the interacting models, it is found that the interacting strength is non-vanishing, but weak for the case of constant interaction function, and the interaction is not obvious for the case of variable interaction function. In addition, for seeing the influence from interaction we also investigate the evolutions of interaction function, effective state parameter for dark energy and energy density of dark matter. At last some geometrical quantities in the interacting scenarios are discussed.
53361927
Resummation prediction on the jet mass spectrum in one-jet inclusive production at the LHC
A bstractWe study the factorization and resummation prediction on the jet mass spectrum in one-jet inclusive production at the LHC based on soft-collinear effective theory. The soft function with anti-kT algorithm is calculated at next-to-leading order and its validity is demonstrated by checking the agreement between the expanded leading singular terms with the exact fixed-order result. The large logarithms lnn(mJ2/pT2) and the global logarithms lnn(s4/pT2) in the process are resummed to all order at next-to-leading logarithmic and next-to-next-to-leading logarithmic level, respectively. The cross section is enhanced by about 23% from the next-to-leading logarithmic level to next-to-next-to- leading logarithmic level. Comparing our resummation predictions with those from Monte Carlo tool PYTHIA and ATLAS data at the 7 TeV LHC, we find that the peak positions of the jet mass spectra agree with those from PYTHIA at parton level, and the predictions of the jet mass spectra with non-perturbative effects are in coincidence with the ATLAS data. We also show the predictions at the future 13 TeV LHC.
119282423
New color-octet axial vector boson revisited
In this paper we reexamine how to utilize the previous proposed color-octet axial-vector boson Z(C) to explain the 3: 4 sigma anomaly of t (t) over bar forward-backward (FB) asymmetry A(FB) for m(t (t) over bar) > 450 GeV observed by CDF. Our numerical results indicate that the best-fit parameters are g(A)(q) = 0: 07, g(A)(Q) 3, and M(C) 440 GeV, which are obtained by fitting the mass dependent AFB and total cross section data provided by a recent CDF measurement. Here g(A)(q) (g(A)(Q)) and MC are the axial couplings among Z(C) with the first two (the third) generation quarks, and Z(C) mass, respectively. We also calculate one-side forward-backward asymmetry AOFB for top and bottom quark pair production at the LHC, focusing on the new contributions from Z(C). Our studies show that AOFB can be utilized to measure the properties of new particle Z(C).
118863203
One-side forward-backward asymmetry in top quark pair production at the CERN Large Hadron Collider
Both D0 and CDF at Tevatron reported the measurements of forward-backward asymmetry in top pair production, which showed possible deviation from the standard model QCD prediction. In this paper, we explore how to examine the same higher-order QCD effects at the more powerful Large Hadron Collider.
118392710
Study of $\psi(3686)\to\pi^0 h_c, h_c\to\gamma\eta_c$ via $\eta_c$ exclusive decays
The process $\psi(3686) \to \pi^0 h_c, h_c \to \gamma \eta_c$ has been studied with a data sample of $106 \pm 4$ million $\psi(3686)$ events collected with the BESIII detector at the BEPCII storage ring. The mass and width of the $P$-wave charmonium spin-singlet state $h_c(^1P_1)$ are determined by simultaneously fitting distributions of the $\pi^0$ recoil mass for 16 exclusive $\eta_c$ decay modes. The results, $M(\hc) = 3525.31 \pm 0.11 {\rm (stat.)} \pm 0.14 {\rm (syst.)}$\,MeV/$c^2$ and $\Gamma(\hc) = 0.70 \pm 0.28 \pm 0.22$\,MeV, are consistent with and more precise than previous measurements. We also determine the branching ratios for the 16 exclusive $\eta_c$ decay modes, five of which have not been measured previously. New measurements of the $\eta_c$ line-shape parameters in the $E1$ transition $h_c\to\gamma\eta_c$ are made by selecting candidates in the $h_c$ signal sample and simultaneously fitting the hadronic mass spectra for the 16 $\eta_c$ decay channels. The resulting $\eta_c$ mass and width values are $M(\eta_c) = 2984.49 \pm 1.16 \pm 0.52$\,MeV/$c^2$ and $\Gamma(\eta_c) = 36.4 \pm 3.2 \pm 1.7$\,MeV.
16884548
The Reach of Tevatron upgrades in gauge mediated supersymmetry breaking models
We examine signals for sparticle production at the Fermilab Tevatron within the framework of gauge-mediated supersymmetry breaking models for four different model lines, each of which leads to qualitatively different signatures. We identify cuts to enhance the signal above standard model backgrounds, and use ISAJET to evaluate the supersymmetry reach of experiments at the Fermilab Main Injector and at the proposed TeV33. For the model lines that we have examined, we find that the reach is at least as large, and frequently larger, than in the minimal supergravity framework. For two of these model lines, we find that the ability to identify {ital b}-quarks and {tau}-leptons with high efficiency and purity is essential for the detection of the signal. {copyright} {ital 1999} {ital The American Physical Society}
55912303
Longitudinal tracking with phase and amplitude modulated RF
Synchrotron motion was induced by phase shifting the rf of the Indiana University Cyclotron Facility (IUCF) cooler-synchrotron. The resulting coherent-bunch motion was tracked in longitudinal phase space for as many as 700000 turns, or for over 350 synchrotron oscillations. Results of recent experimental studies of longitudinal motion in which the rf phase and amplitude were harmonically modulated are also presented. Comparisons of experimental data, with numerical simulations, assuming independent particle motion, are made. Observed multiparticle effects are also discussed.<<ETX>>