452 research outputs found
Renormalization of Bilinear Quark Operators for Overlap Fermions
We present non-perturbative renormalization constants of fermionic bilinears
on the lattice in the quenched approximation at beta=6.1 using an overlap
fermion action with hypercubic(HYP)-blocked links. We consider the effects of
the exact zero modes of the Dirac operator and find they are important in
calculating the renormalization constants of the scalar and pseudoscalar
density. The results are given in the RI' and MS bar schemes and compared to
the perturbative calculations.Comment: 14 pages, 13 figure
Highlights of Supersymmetric Hypercharge Triplets
The discovery of a standard model (SM)-like Higgs boson with a relatively
heavy mass and hints of di-photon excess has deep implication to
supersymmetric standard models (SSMs). We consider the SSM extended with
hypercharge triplets, and investigate two scenarios of it: (A) Triplets
significantly couple to the Higgs doublets, which can substantially raise
and simultaneously enhance the Higgs to di-photon rate via light chargino
loops; (B) Oppositely, these couplings are quite weak and thus can not be
raised. But the doubly-charged Higgs bosons, owing to the gauge group
structure, naturally interprets why there is an excess rather than a deficient
of Higgs to di-photon rate. Additionally, the pseudo Dirac triplet fermion is
an inelastic non-thermal dark matter candidate. Light doubly-charged particles,
especially the doubly-charged Higgs boson around 100 GeV in scenario B, are
predicted. We give a preliminary discussion on their search at the LHC.Comment: JHEP version. Typos fixed, comments, references and acknowledge adde
Higgs Boson Mass and Complex Snuetrino Dark Matter in the Supersymmetric Inverse Seesaw Models
The discovery of a relatively heavy Standard Model (SM) -like Higgs boson
challenges naturalness of the minimal supersymmetric standard model (MSSM) from
both Higgs and dark matter (DM) sectors. We study these two aspects in the MSSM
extended by the low-scale inverse seesaw mechanism. Firstly, it admits a
sizable radiative correction on the Higgs boson mass m_h, up to \sim 4 GeV in
the case of an IR-fixed point of the coupling Y_\nu LH_u\nu^c and a large
sneutrino mixing. Secondly, the lightest sneutrino, highly complex as expected,
is a viable thermal DM candidate. Owing to the correct relic density and
XENON100, two cases survive: a Higgs-portal complex DM with mass lying around
the Higgs pole or above threshold, and a coannihilating DM with slim
prospect of detection. Given an extra family of sneutrinos, both scenarios
naturally work when we attempt to suppress the DM left-handed sneutrino
component, confronting with enhancing m_h.Comment: 19 pages, 6 figures, JHEP versio
Simplified Supersymmetry with Sneutrino LSP at 8 TeV LHC
The current searches of supersymmetry (SUSY) are based on the neutralino
lightest sparticle (LSP). In this article we instead focus on SUSY with
sneutrino LSP. It is well motivated in many contexts, especially in which
sneutrino services as a dark matter candidate. We first develop a simplified
model, which contains the stop, chagino/neutralino and sneutrino, to describe
the LHC phenomenologies of a large class of models with sneutrino LSP. Then we
investigate bounds on the model using the SUSY searches at the 8 TeV LHC.
Strong exclusion limits are derived, e.g., masses of stop and chargino can be
excluded up to about 900 GeV and 550 GeV, respectively. We also propose
optimizations for some searches without turning to higher energy and
luminosity.Comment: 26 pages, 8 figures,Minor corrections,References adde
Probing the CP-even Higgs Sector via in the Natural NMSSM
After the discovery of a Standard Model (SM) like Higgs boson, naturalness
strongly favors the next to the Minimal Supersymmetric SM (NMSSM). In this
letter, we point out that the most natural NMSSM predicts the following CP-even
Higgs sector: (A) is the SM-like Higgs boson with mass
pushed-upward by a lighter with mass overwhelmingly within
; (B) GeV; (C)
has a significant coupling to top quarks and can decay to with a
large branching ratio. Using jet substructure we show that all the three Higgs
bosons can be discovered via at
the 14 TeV LHC. Especially, the LEP-LHC scenario with GeV has a
very good discovery potential.Comment: 5 pages, 2 figures. Some typos corrected and reference adde
Quark condensate in two-flavor QCD
We compute the condensate in QCD with two flavors of dynamical fermions using
numerical simulation. The simulations use overlap fermions, and the condensate
is extracted by fitting the distribution of low lying eigenvalues of the Dirac
operator in sectors of fixed topological charge to the predictions of Random
Matrix Theory.Comment: revtex, 18 pages, 4 postscript figures. V.2, the published version,
corrects an error for the shape facto
Light Doubly Charged Higgs Boson via the Channel at LHC
The doubly charged Higgs bosons searches at the Large Hadron
Collider (LHC) have been studied extensively and strong bound is available for
dominantly decaying into a pair of same-sign di-leptons. In this
paper we point out that there is a large cavity in the light mass
region left unexcluded. In particular, can dominantly decay into
or (For instance, in the type-II seesaw mechanism the triplet
acquires a vacuum expectation value around 1 GeV.), and then it is found that
with mass even below remains untouched by the current
collider searches. Searching for such a at the LHC is the topic of
this paper. We perform detailed signal and background simulation, especially
including the non-prompt background which is the dominant one
nevertheless ignored before. We show that such should be
observable at the 14 TeV LHC with 10-30 fb integrated luminosity.Comment: 23 pages, 4 figures, typos fixed, references added, EPJC versio
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