118746690
Constraining Top partner and Naturalness at the LHC and TLEP
Abstract We investigate indirect constraints on the top partner within the minimal fermionic top partner model. By performing a global fit of the latest Higgs data, B s → μ + μ − measurements and the electroweak precision observables we find that the top partner with the mass up to 830 GeV is excluded at 2σ level. Our bound on the top partner mass is much stronger than the bounds obtained from the direct searches at the LHC. Under the current constraints the fine-tuning measure is less than 9% and the branching ratio of T → t Z is bounded between 14% and 25%. We also find that precise measurements of Higgs couplings at 240 GeV TLEP will constrain the top partner mass in multi-TeV region.
53120988
Probing light higgsinos in natural SUSY from monojet signals at the LHC
A bstractWe investigate a strategy to search for light, nearly degenerate higgsinos within the natural MSSM at the LHC. We demonstrate that the higgsino mass range μ in 100−160 GeV, which is preferred by the naturalness, can be probed at 3σ significance through the monojet search at 14 TeV HL-LHC with 3000 fb−1 luminosity. The proposed method can also probe certain region in the parameter space for the lightest neutralino with a high higgsino purity, that cannot be reached by planned direct detection experiments at XENON-1 T(2017).
119258135
One-loop effects on top pair production in the littlest Higgs model with T-parity at the LHC
In this work, we systematically investigate the one-loop corrections to $t\bar{t}$ production in the littlest Higgs model with T-parity (LHT) at the LHC for $\sqrt{s}=8,14~\mbox{TeV}$. We focus on the effects of LHT particles on $t\bar{t}$ cross section, polarization asymmetries, spin correlation and charge asymmetry at the LHC. We also study the top quark forward–backward asymmetry at Tevatron and its correlations with the LHC observables. We found that: (1) the contributions of the LHT particles to $t\bar{t}$ production can only reach about 1 % at the 14 TeV LHC. Meanwhile, the anomalous top quark forward–backward asymmetry at Tevatron is also hardly to be explained in the LHT model. (2) The parity violating asymmetries in $t\bar{t}$ production, such as left–right asymmetry |ALR| and the polarization |Pt| can, respectively, reach 1.1 % and 0.5 %, which may have the potential to provide a signal of LHT at the LHC.
115853629
QCD corrections to the production of $t\bar{t}\gamma$ at the ILC
A precise calculation of the top quark pair production associated with a hard photon is essential for testing the electroweak property of the top quark in the Standard Model (SM). We investigate the one-loop QCD corrections to the process $e^{+}e^{-} \to t\bar{t}\gamma$ at the International Linear Collider (ILC), and find that the $K$-factor can be as large as 1.238 (1.105, 1.060) for a center-of-mass energy $\sqrt{s}=500 (800, 1500)$ GeV. The transverse momentum distributions of the top quark and photon are respectively shown at leading order (LO) and next-to-leading order(NLO). Due to the asymmetric rapidity distribution of the top (anti-top) quark, we also study the top quark forward-backward asymmetry ($A^{t}_{FB}$) in $t\bar{t}\gamma$ production at NLO, which is found to be 45.82 (55.25, 55.89)% for $\sqrt{s}=500 (800, 1500)$ GeV.
119293139
Probing topcolor-assisted technicolor from top charge asymmetry and triple-top production at the LHC
In a topcolor-assisted technicolor model (TC2) with large FCNC top quark couplings, we study its correlated contributions to the top quark forward-backward asymmetry (A(FB)) at the Tevatron, the top charge asymmetry (A(C)) and the triple-top production at the LHC. Under current constraints on the top quark from the LHC and Tevatron (such as the total and differential production rates), we scan the parameter space of such a TC2 model. We find that in the allowed parameter space the TC2 model can explain the Tevatron measured A(FB) at 2 sigma level, but meanwhile significantly enhance A(C) at the LHC. Such enhanced A(C), albeit currently allowed by the LHC measurement at 2 sigma level, will serve as a test of TC2 with the improvement of measurement precision at the LHC. Then with all the constraints (including the requirement to explain A(FB) at 2 sigma level and satisfying the current LHC measurement of A(C) at 2 sigma level), we find that the TC2 model can induce sizable triple-top production at the 14 TeV LHC (the production rate can maximally reach 16 pb). Due to the low SM backgrounds, the triple-top production can also be a good probe for TC2 model, complementary to A(C). (C) 2012 Elsevier B.V. All rights reserved.
119208960
Revisiting Associated Production of 125 GeV Higgs Boson with a Photon at a Higgs Factory
Considering the constraints from the flavor physics, precision electroweak measurements, Higgs data and dark matter detections, we scan over the parameter space of the MSSM and calculate the cross section of e + e → h in the allowed parameter space. Since the loop-induced gauge couplings h and hZ can simultaneously contribute to the process e + e → h, we find the cross section can be sizably enhanced by a light stau, maximally 1.47(1.38) times larger than the SM prediction at √ s = 240(350) GeV. So with the high luminosity, the measurement of e + e → h may be used to test the anomalous gauge couplings h and hZ in the MSSM at a Higgs Factory.
120721608
EFFECTS OF TEMPERATURE ON THE STABILITY OF PROTONEUTRON STARS WITH HYPERONS
In the framework of the relativistic mean field theory, the stability of thermal protoneutron stars is investigated. There is a highest possible temperature for a stable protoneutron star. A stable protoneutron star may be a metastable one if its mass is too large. As the temperature increases, the metastable mass range of protoneutron stars narrows. With the increase of temperature, the probability that a stable protoneutron star is a metastable one increases. A really stable protoneutron star with higher temperature can contain more species of hyperons. The case of SN 1987A is analyzed connected with the results in this article.