65 research outputs found
Standard Model discovery potential with ATLAS
This contribution summarizes the discovery potential of the Standard Model
Higgs boson using the decay with the ATLAS detector. The
relevant detector performance aspects of photon reconstruction, photon
identification and trigger issues are discussed. The potential of inclusive as well as Higgs boson searches in association with one or two
hard jets are studied. The discovery potential is finally assessed using an
unbinned multivariate maximum-likelihood fit with an expected integrated
luminosity of .Comment: 5 pages, 4 figures, Contribution to Conference LHC0
Search for SM Higgs Decaying to Two Photons via ATLAS Detector
This dissertation reports the discovery potential of the Standard Model Higgs boson with the di-photon decay using the ATLAS detector. First, photon calibration techiques is studied and a likelihood method for photon identification and jet rejection is developed. A method to evaluate photon identification and fake photon backgrounds with data was also discussed. The potential of an inclusive SM Higgs decaying to two photons search and Higgs boson searches in association with one or two high jets is evaluated. Finally an extended maximum likelihood fit together with event classifications was performed to estimate the sensitivity of the search. With 30 fb data, the expected sensitivity for the channel Higgs decaying to two photons is above 5 sigma for Higgs masses between 120 and 140 GeV
Instantaneous Symmetry Breaking to the Non-observed Dark Matter
A theory explaining the non-observation of the dark matter and the source of
the dark energy is presented in this letter. By integrating the asymmetrical
potential and the Higgs potential, we provide a model with instantaneous
symmetrical breaking and stable symmetrical breaking, resulting in the
non-observed dark matter and observed matter respectively. Two crucial
parameters in this model are the frequency and strength of the symmetry
breaking from the vacuum: the former helps explain the impact of the effective
mass from the dark matter; the latter determines the source of the dark energy.
The expected strength in a certain period varies, causing the accelerating or
deccelerating expansions of the universe. Considering the expected strength
correlated with the vacuum expectation value and basing on the possible
variations of the measured masses of the fundamental particles such as Z boson
over time, one can perhaps derive the exact stage of the current universe
Searching for Heavier Higgs Boson via Di-Higgs Production at LHC Run-2
The LHC discovery of a light Higgs particle (125GeV) opens up new
prospect for searching heavier Higgs boson(s) at the LHC Run-2, which will
unambiguously point to new physics beyond the standard model (SM). We study the
detection of a heavier neutral Higgs boson via di-Higgs production
channel at the LHC (14TeV), . This
directly probes the cubic Higgs interaction, which exists in most
extensions of the SM Higgs sector. For the decay products of final states
, we include both pure leptonic mode and semi-leptonic mode .
We analyze signals and backgrounds by performing fast detector simulation for
the full processes and , over the mass range
GeV. For generic two-Higgs-doublet models (2HDM), we present the
discovery reach of the heavier Higgs boson at the LHC Run-2, and compare it
with the current Higgs global fit of the 2HDM parameter space.Comment: Phys.Lett.B Final Version. 16pp (9 Figs + 4 Tables). Only minor
refinements, references adde
LHC Search of New Higgs Boson via Resonant Di-Higgs Production with Decays into 4W
Searching for new Higgs particle beyond the observed light Higgs boson
h(125GeV) will unambiguously point to new physics beyond the standard model. We
study the resonant production of a CP-even heavy Higgs state in the
di-Higgs channel via, , at the LHC Run-2 and
the high luminosity LHC (HL-LHC). We analyze two types of the decay modes,
one with the same-sign di-leptons () and the
other with tri-leptons (). We
perform a full simulation for the signals and backgrounds, and estimate the
discovery potential of the heavy Higgs state at the LHC Run-2 and the HL-LHC,
in the context of generical two-Higgs-doublet models (2HDM). We determine the
viable parameter space of the 2HDM as allowed by the theoretical constraints
and the current experimental limits. We systematically analyze the allowed
parameter space of the 2HDM which can be effectively probed by the heavy Higgs
searches of the LHC, and further compare this with the viable parameter region
under the current theoretical and experimental bounds.Comment: v3: JHEP published version, 34pp, 10 Figs(36 plots) and 9 Tables.
Only minor typos fixed, references added. v2: JHEP version. All results and
conclusions un-changed, discussions and references added. (This update is
much delayed due to author's traveling and flu.
The expected measurement precision of the branching ratio of the Higgs decaying to the di-photon at the CEPC
This paper presents the prospects of measuring in 3 decay channels using the baseline detector with at the Circular Electron Positron Collider (CEPC) . The simulated
Monte Carlo events are generated and scaled to an integrated luminosity of 5.6
to mimic the data. Extrapolated results to 20 are also
shown. The expected statistical precision of this measurement after combining 3
channels of boson decay is 7.7\%. With some preliminary estimation on the
systematical uncertainties, the total precision is 7.9\%. The performance of
CEPC electro-magnetic calorimeter (ECAL) is studied by smearing the photon
energy resolution in simulated events in channel. In present ECAL design, the stochastic term in
resolution plays the dominant role in the precision of Higgs measurements in channel. The impact of the resolution on the measured
precision of as well as the
optimization of ECAL constant term and stochastic term are studied for the
further detector design
Probing Higgs properties at the CEPC
In the Circular Electron Positron Collider (CEPC), a measurement of the Higgs
mixing through process is presented, with $5.6\
\mbox{ab}^{-1}e^{+} e^{-}240\ \mathrm{GeV}CP\hat{\alpha}_{A \tilde{Z}} -8.27\times
10^{-2}8.09 \times 10^{-2}\hat{\alpha}_{Z \tilde{Z}}-2.15 \times 10^{-2}2.02 \times 10^{-2}95\%CP$ properties at
the CEPC
Application of Quantum Machine Learning in a Higgs Physics Study at the CEPC
Machine learning has blossomed in recent decades and has become essential in
many fields. It significantly solved some problems in particle physics --
particle reconstruction, event classification, etc. However, it is now time to
break the limitation of conventional machine learning with quantum computing. A
support-vector machine algorithm with a quantum kernel estimator (QSVM-Kernel)
leverages high-dimensional quantum state space to identify a signal from
backgrounds. In this study, we have pioneered employing this quantum machine
learning algorithm to study the process at the
Circular Electron-Positron Collider (CEPC), a proposed Higgs factory to study
electroweak symmetry breaking of particle physics. Using 6 qubits on quantum
computer simulators, we optimised the QSVM-Kernel algorithm and obtained a
classification performance similar to the classical support-vector machine
algorithm. Furthermore, we have validated the QSVM-Kernel algorithm using
6-qubits on quantum computer hardware from both IBM and Origin Quantum: the
classification performances of both are approaching noiseless quantum computer
simulators. In addition, the Origin Quantum hardware results are similar to the
IBM Quantum hardware within the uncertainties in our study. Our study shows
that state-of-the-art quantum computing technologies could be utilised by
particle physics, a branch of fundamental science that relies on big
experimental data
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