56228854
Constraints of dark matter direct detection experiments on the MSSM and implications for LHC Higgs searches
Assuming the lightest neutralino solely composes the cosmic dark matter, we examine the constraints of the CDMS-II and XENON100 dark matter direct searches on the parameter space of the MSSM Higgs sector. We find that the current CDMS-II/XENON100 limits can exclude some of the parameter space which survive the constraints from the dark matter relic density and various collider experiments. We also find that in the currently allowed parameter space, the charged Higgs boson is hardly accessible at the LHC for an integrated luminosity of 30 fb−1, while the neutral non-SM Higgs bosons (H,A) may be accessible in some allowed region characterized by a large μ. The future XENON100 (6000 kg-days exposure) will significantly tighten the parameter space in case of nonobservation of dark matter, further shrinking the likelihood of discovering the non-SM Higgs bosons at the LHC. PACS numbers: 14.80.Da,14.80.Ly
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.
123950174
THE PHASE-TRANSITION GENERATED BY RADIAL MODE OF THE HIGGS FIELD IN LATTICE Z(2) GAUGE-HIGGS MODEL
We study the 4-dimensional lattice Z(2) gauge-Higgs theory in the variational cumulant expansion approach. It is shown that the existence of the first order phase transition between Higgs and confinement regions is fundamentally dependent on the fluctuation of the radial mode of the scalar (Higgs) field.
119418509
SuperWIMP dark matter scenario in light of WMAP
Abstract.The heavy gravitino in the minimal supergravity (mSUGRA) models is likely to be the lightest supersymmetric particle (LSP). Produced from the late decays of the metastable weakly interacting massive particles (WIMPs) such as the lightest neutralinos, the stable gravitinos can be plausible candidates for the cold dark matter in the universe. Such gravitino dark matter can naturally evade the current detection experiments due to its superweak couplings. However, this scenario must be subjected to the constraints from the big bang nucleosynthesis (BBN) predictions for light element abundances as well as the Wilkinson microwave anisotropy probe (WMAP) data for the relic density. Assuming the popular case in which the lightest neutralino is the next-to-lightest supersymmetric particle (NLSP), we find that requiring BBN predictions for light element abundances to agree with the WMAP data can impose upper and lower mass bounds on both the gravitino LSP and the neutralino NLSP. A scan over the mSUGRA parameter space, subjected to the BBN constraints, the WMAP data and the $b\to s \gamma$ bounds, shows that the low $\tan\beta$ ($\lesssim 40$) region as well as the region accessible at the CERN Large Hadron Collider (LHC) will be severely constrained. Such stringent constraints on the parameter space might be instructive for testing this scenario in future collider experiments.
119516872
Muon anomalous magnetic moment in technicolor models
Contributions to the muon anomalous magnetic moment are evaluated in the technicolor model with scalars and topcolor assisted technicolor model, In the technicolor model with scalers, the additional contributions come from the loops of scalers, which were found sizable only for a very large f/f' disfavored by the experiment of h --> s gamma. The topcolor effect is also found to be large only for an unnaturally large tan theta', and thus the previously evaluated loop effects of extended technicolor bosons, suppressed by m(mu)(2)/M-ETC(2), must be resorted to account for the E821 experiment. So, if the E821 experiment result persists, it would be a challenge to technicolor models. (C) 2001 Published by Elsevier Science B.V.
40224148
Virtual effects of split-SUSY in Higgs productions at linear colliders
In split supersymmetry, gauginos and higgsinos are the only supersymmetric particles possibly accessible at foreseeable colliders like the CERN Large Hadron Collider (LHC) and the International Linear Collider (ILC). In order to account for the cosmic dark matter measured by WMAP, these gauginos and higgsinos are stringently constrained and could be explored at the colliders through their direct productions and/or virtual effects in some processes. The clean environment and high luminosity of the ILC render the virtual effects at percent level meaningful in unraveling the new physics effects. In this work we assume split supersymmetry and calculate the virtual effects of the WMAP-allowed gauginos and higgsinos in the Higgs productions e+e-→Zh and e+e-→νeν̄eh through WW fusion at the ILC. We find that the production cross section of e+e-→Zh can be altered by a few percent in some part of the WMAP-allowed parameter space, while the correction to the WW fusion process e+e-→νeν̄eh is below 1%. Such virtual effects are correlated with the cross sections of chargino pair productions and can offer complementary information in probing split supersymmetry at the colliders.
14239579
Confinement of Higgs bosons from hidden symmetry and convexity
In the full effective potential (EFP) approach, we find that spontaneous symmetry breaking (SSB) can, with the convexity of the full EFP, lead to the prediction of the IR confinement of Higgs particles, adding difficulty to the experimental identification of Higgs particles. The short distance behaviors remain intact. The whole presentation is given in the understanding that any QFT becomes UV well defined in a more complete underyling theory according to a recently proposed strategy.
14573379
Harmonic scaling laws and underlying structures
Based on the effective field theory philosophy, a universal form of the scaling laws could be easily derived with the scaling anomalies naturally clarified as the decoupling effects of underlying physics. In the novel framework, the conventional renormalization group equations and Callan-Symanzik equations could be reproduced as special cases and a number of important and difficult issues around them could be clarified. The underlying theory point of view could envisage a harmonic scaling law that help to fix the form of the loop amplitudes through anomalies, and the heavy field decoupling can be incorporated in this underlying theory approach in a more unified manner.
12719675
Quantum field theory: Finiteness and Effectiveness
A new attempt is demonstrated that QFTs can be UV finite if they are viewed as the low energy effective theories of a fundamental underlying theory (that is complete and well-defined in all respects) according to the modern standard point of view. This approach works for any interaction model and space-time dimension. It is much simpler in principle and in technology comparing to any known renormalization program.Unlike the known renormalization methods, the importance of the procedure for defining the ambiguities (corresponding to the choice of the renormalization conditions in the conventional program) is fully appreciated in the new approach. It is shown that the high energy theory(s) or the underlying theory(s) in fact 'stipulates (stipulate)' the low energy and effective ones through these definitions within our approach while all the conventional methods miss this important point. Some simple but important nonperturbative examples are discussed to show the power and plausibility of the new approach. Other related issues (especially the IR problem and the implication of our new approach for the canonical quantization procedure) are briefly touched.
10538446
Why have Higgs particles not been found yet
It is suggested that within the effective potential approach, convex-ity and spontaneous symmetry breaking(SSB) make the Higgs bosons bizarre and experimentally nonexistent, a possible resolution of the Higgs puzzle. This observation might have quite some nontrivial consequences for the Standard Model (SM) and particle physics. By now, the experimentally nonexistence of Higgs particles predicted by the SM has become a puzzle in spite that the SM has been deemed as well established by the community of high energy physics (HEP), especially given that the estimated mass range of Higgs bosons has already become accessible [1]. There can be found a number of attempts to explain this puzzling situation. There is even modeling work trying to provide masses for intermediate gauge bosons without introducing Higgs model [2]. In this report, We attempt to suggest an alternative way of looking at this problem still within the SM theory. We will adopt the effective potential 1
119915103
Trace anomaly and mass independent rational terms
Abstract We perform a new investigation to show that the trace anomaly in Minkowskian spacetime is originated by a kind of mass independent rational term which is definite and nonlocal. Hence it is regularization independent and may provide more physical insight. A simple way for calculating trace anomalies is proposed and several examples are given.