scholarly journals The measurement of the $$H\rightarrow \tau \tau $$ signal strength in the future $$e^{+}e^{-}$$ Higgs factories

2020 ◽  
Vol 80 (1) ◽  
Author(s):  
Dan Yu ◽  
Manqi Ruan ◽  
Vincent Boudry ◽  
Henri Videau ◽  
Jean-Claude Brient ◽  
...  
Keyword(s):  
Linear Collider ◽  
Simulation Analysis ◽  
Center Of Mass ◽  
International Linear Collider ◽  
Signal Strength ◽  
Relative Accuracy ◽  
Hadronic Decay ◽  
Beam Polarization ◽  
Baseline Design ◽  
Electron Positron

AbstractThe Circular Electron Positron Collider and the International Linear Collider are two electron-positron Higgs factories. They are designed to operate at a center-of-mass energy of 240 and 250 GeV and accumulate 5.6 and 2 $$ab^{-1}$$ab-1 of integrated luminosity. This paper estimates their performance on the $$H \rightarrow \tau ^{+}\tau ^{-}$$H→τ+τ- benchmark measurement. Using the full simulation analysis, the CEPC is expected to measure the signal strength to a relative accuracy of 0.8%. Extrapolating to the ILC setup, we conclude the ILC can reach a relative accuracy of 1.1% or 1.2%, corresponding to two benchmark beam polarization setups. The physics requirement on the mass resolution of the Higgs boson with hadronic decay final states is also discussed, showing that the CEPC baseline design and reconstruction fulfill the accuracy requirement of the $$H\rightarrow \tau ^{+}\tau ^{-}$$H→τ+τ- signal strength.

Preliminary conceptual design about the CEPC calorimeters

2016 ◽  
Vol 31 (33) ◽  
pp. 1644026 ◽  
Author(s):  
Haijun Yang
Keyword(s):  
Conceptual Design ◽  
Linear Collider ◽  
International Linear Collider ◽  
Electromagnetic Calorimeter ◽  
Hadronic Jets ◽  
Baseline Design ◽  
Active Sensor ◽  
Electron Positron ◽  
Physics Potential ◽  
Conceptual Design Report

The Circular Electron Positron Collider (CEPC) as a Higgs factory was proposed in September 2013. The preliminary conceptual design report was completed in 2015.1 The CEPC detector design was using International Linear Collider Detector — ILD2 as an initial baseline. The CEPC calorimeters, including the high granularity electromagnetic calorimeter (ECAL) and the hadron calorimeter (HCAL), are designed for precise energy measurements of electrons, photons, taus and hadronic jets. The basic resolution requirements for the ECAL and HCAL are about 16%[Formula: see text][Formula: see text] (GeV) and 50%[Formula: see text][Formula: see text] (GeV), respectively. To fully exploit the physics potential of the Higgs, [Formula: see text], [Formula: see text] and related Standard Model processes, the jet energy resolution is required to reach 3%–4%, or 30%/[Formula: see text] (GeV) at energies below about 100 GeV. To achieve the required performance, a Particle Flow Algorithm (PFA) — oriented calorimetry system is being considered as the baseline design. The CEPC ECAL detector options include silicon–tungsten or scintillator–tungsten structures with analog readout, while the HCAL detector options have scintillator or gaseous detector as the active sensor and iron as the absorber. Some latest R&D studies about ECAL and HCAL within the CEPC working group is also presented.

scholarly journals Tau $$g{-}2$$ at $$e^-e^+$$ colliders with momentum-dependent form factor

2021 ◽  
Vol 81 (2) ◽  
Author(s):  
Hieu Minh Tran ◽  
Yoshimasa Kurihara
Keyword(s):  
Form Factor ◽  
Linear Collider ◽  
International Linear Collider ◽  
Large Mass ◽  
New Physics ◽  
Magnetic Form Factor ◽  
Beam Polarization ◽  
Electron Positron ◽  
Dependent Form ◽  
Model Independent

AbstractThe deviation between the prediction based on the standard model and the measurement of the muon $$g{-}2$$ g - 2 is currently at $$3{-}4 \sigma $$ 3 - 4 σ . If this discrepancy is attributable to new physics, it is expected that the new contributions to the tau $$g{-}2$$ g - 2 even larger than those of muon due to its large mass. However, it is much more difficult to directly measure the tau $$g{-}2$$ g - 2 because of its short lifetime. In this report, we consider the effect of the tau $$g{-}2$$ g - 2 at $$e^-e^+$$ e - e + colliders using a model independent approach. Using the tau pair production channel at the Large Electron Position Collider (LEP), we have determined the allowed range for the new physics contribution of the tau $$g{-}2$$ g - 2 assuming a q-square-dependence ansatz for the magnetic form factor. We also investigated the prospect at future $$e^+e^-$$ e + e - colliders, such as International Linear Collider, the Compact Linear Collider, the Future Circular $$e^+e^-$$ e + e - Collider, and Circular Electron Positron Collider, and determined the expected allowed range for the new physics contribution to the tau anomalous magnetic moment. The best limits are about $$4{-}5$$ 4 - 5 times more severe than the LEP one due to the beam polarization and the high luminosities at future colliders.

scholarly journals Probe of the Anomalous Quartic Couplings with Beam Polarization at the CLIC

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
A. Senol ◽  
M. Köksal ◽  
S. C. İnan
Keyword(s):  
Confidence Level ◽  
Semileptonic Decay ◽  
Linear Collider ◽  
Decay Channel ◽  
Center Of Mass ◽  
Positron Beam ◽  
Beam Polarization ◽  
Electron Positron ◽  
Integrated Luminosity

We have investigated the anomalous quartic couplings defined by the dimension-8 operators in semileptonic decay channel of thee+e-→νeW-W+ν-eprocess for unpolarized and polarized electron (positron) beam at the Compact Linear Collider. We give the 95% confidence level bounds on the anomalousfS0/Λ4,fS1/Λ4, andfT0/Λ4couplings for various values of the integrated luminosities and center-of-mass energies. The best sensitivities obtained on anomalousfS0/Λ4,fS1/Λ4, andfT0/Λ4couplings through the processe+e-→νeW-W+ν-ewith beam polarization ats=3 TeV and an integrated luminosity ofLint=2000 fb-1are[-4.05;3.67]×10-12 GeV-4,[-3.08;2.12]×10-12 GeV-4, and[-1.98;0.64]×10-13 GeV-4, which show improvement over the current bounds.

CEPC Z-pole polarization design studies

2021 ◽  
pp. 2142003
Author(s):  
Wenhao Xia ◽  
Jie Gao ◽  
Yiwei Wang ◽  
Dou Wang
Keyword(s):  
Beam Energy ◽  
Center Of Mass ◽  
Transverse Polarization ◽  
Beam Polarization ◽  
Energy Measurement ◽  
Design Studies ◽  
Electron Positron ◽  
Polarized Beam ◽  
Different Types ◽  
Schematic Design

In this paper, we give preliminary designs of beam polarization manipulations by inserting three different types of insertions in the Circular Electron–Positron Collider (CEPC) at center-of-mass energies of 91 GeV (Z-pole). With the wigglers in the collider ring, we can obtain 5% transverse polarization in 1.1 h for the precise energy measurement. To overcome depolarization effects as the beam energy rises from 10 GeV to 45.5 GeV in the booster ring, Siberian snakes based on helical magnets are adopted. Finally, for longitudinally polarized beam collisions, a schematic design of spin rotators based on solenoids in the collider ring is studied.

scholarly journals Indirect reach of heavy MSSM Higgs bosons by precision measurements at future lepton colliders

2015 ◽  
Vol 30 (33) ◽  
pp. 1550192 ◽  
Author(s):  
Mitsuru Kakizaki ◽  
Shinya Kanemura ◽  
Mariko Kikuchi ◽  
Toshinori Matsui ◽  
Hiroshi Yokoya
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
W Boson ◽  
Linear Collider ◽  
Standard Model Prediction ◽  
Branching Fraction ◽  
International Linear Collider ◽  
Higgs Bosons ◽  
Boson Mass ◽  
Electron Positron

In the Minimal Supersymmetric Standard Model (MSSM), the bottom Yukawa coupling of the Higgs boson can considerably deviate from its Standard Model prediction due to nondecoupling effects. We point out that the ratio of the Higgs boson decay branching fraction to a bottom quark pair and that to a W-boson pair from the same production channel is particularly sensitive to large additional MSSM Higgs boson mass regions at future electron–positron colliders. Based on this precision measurement, we explicitly show the indirect discovery reach of the additional Higgs bosons according to planned programs of the International Linear Collider.

scholarly journals NLO QCD corrections to exclusive quarkonium-pair production in photon–photon collision

2020 ◽  
Vol 80 (9) ◽  
Author(s):  
Hao Yang ◽  
Zi-Qiang Chen ◽  
Cong-Feng Qiao
Keyword(s):  
Pair Production ◽  
Cross Sections ◽  
Linear Collider ◽  
International Linear Collider ◽  
Leading Order ◽  
Numerical Result ◽  
Electron Positron ◽  
Belle Ii ◽  
Exclusive Processes ◽  
Photon Collision

AbstractWe calculate the next-to-leading order (NLO) quantum chromodynamics (QCD) corrections to the exclusive processes $$\gamma +\gamma \rightarrow {\mathcal {Q}}+{\mathcal {Q}}$$ γ + γ → Q + Q , with $${\mathcal {Q}}=J/\psi ,\ \eta _c,\ \Upsilon $$ Q = J / ψ , η c , Υ , or $$\eta _b$$ η b , in the framework of non-relativistic QCD (NRQCD) factorization formalism. The cross sections at the SuperKEKB electron–positron collider, as well as at the future colliders, like the circular electron positron collider (CEPC) and the international linear collider (ILC), are evaluated. Numerical result indicates that the processes for $$J/\psi $$ J / ψ -pair production and $$\eta _c$$ η c -pair production are hopefully observable at the Belle II detector within the next decade.

scholarly journals Conceptual design studies for a CEPC detector

2016 ◽  
Vol 31 (33) ◽  
pp. 1644021 ◽  
Author(s):  
S. V. Chekanov ◽  
M. Demarteau
Keyword(s):  
Conceptual Design ◽  
Linear Collider ◽  
International Linear Collider ◽  
Silicon Detector ◽  
Design Studies ◽  
Electron Positron ◽  
Physics Potential

The physics potential of the Circular Electron Positron Collider (CEPC) can be significantly strengthened by two detectors with complementary designs. A promising detector approach based on the Silicon Detector (SiD) designed for the International Linear Collider (ILC) is presented. Several simplifications of this detector for the lower energies expected at the CEPC are proposed. A number of cost optimizations of this detector are illustrated using full detector simulations. We show that the proposed changes will enable one to reach the physics goals at the CEPC.

scholarly journals PROGRESS WITH THE JLC/NLC X-BAND LINEAR COLLIDER DESIGN

2001 ◽  
Vol 16 (supp01c) ◽  
pp. 1193-1196
Author(s):  
T. O. Raubenheimer
Keyword(s):  
Linear Collider ◽  
Center Of Mass ◽  
Cost Savings ◽  
Significant Cost ◽  
Center Of Mass Energy ◽  
Physics Program ◽  
Electron Positron ◽  
X Band ◽  
Beam Delivery ◽  
Beam Delivery System

An electron/positron linear collider with a center-of-mass energy between 0.5 and 1 TeV would be an important complement to the physics program of the LHC in the next decade. The Next Linear Collider (NLC) is being designed by a US collaboration (FNAL, LBNL, LLNL, and SLAC) which is working closely with the Japanese collaboration that is designing the Japanese Linear Collider (JLC). This paper will discuss the technical difficulties encountered as well as the changes that have been made to the NLC design over the last year. These changes include improvements to the X-band rf system as well as modifications to the beam delivery system. The net effect has been to reduce the length of the collider from about 32 km to 25 km and to reduce the number of klystrons and modulators by a factor of two. Together these lead to significant cost savings.

FIRST MEASUREMENT OF THE LEFT-RIGHT ASYMMETRY IN Z-BOSON PRODUCTION

1993 ◽  
Vol 08 (24) ◽  
pp. 2237-2248 ◽  
Author(s):  
◽  
K. ABE ◽  
I. ABT ◽  
P. D. ACTON ◽  
C. E. ADOLPHSEN ◽  
...  
Keyword(s):  
Z Boson ◽  
Linear Collider ◽  
Center Of Mass ◽  
Positron Beam ◽  
Beam Polarization ◽  
Boson Production ◽  
Weak Mixing Angle ◽  
Center Of Mass Energy ◽  
Average Electron ◽  
Left Right Asymmetry

We present the first measurement of the left-right cross-section asymmetry (A LR ) in Z-boson production observed at the SLAC Linear Collider. In 1992 the SLD detector recorded 10 224 Z events produced by the collision of longitudinally polarized electrons with an unpolarized positron beam at a center-of-mass energy of 91.55 GeV. The average electron beam polarization during the run was (22.4 ± 0.6)%. We measure A LR to be 0.100 ± 0.0440 (stat.) ±0.004 (syst.) , which determines the effective weak mixing angle to be [Formula: see text].

Linear Colliders

2014 ◽  
Vol 07 ◽  
pp. 115-136
Author(s):  
Akira Yamamoto ◽  
Kaoru Yokoya
Keyword(s):  
Linear Collider ◽  
International Linear Collider ◽  
Electron Positron ◽  
Linear Colliders ◽  
Technical Design Report ◽  
Superconducting Rf ◽  
Technical Features ◽  
Energy Frontier ◽  
Conceptual Design Report

An overview of linear collider programs is given. The history and technical challenges are described and the pioneering electron–positron linear collider, the SLC, is first introduced. For future energy frontier linear collider projects, the International Linear Collider (ILC) and the Compact Linear Collider (CLIC) are introduced and their technical features are discussed. The ILC is based on superconducting RF technology and the CLIC is based on two-beam acceleration technology. The ILC collaboration completed the Technical Design Report in 2013, and has come to the stage of "Design to Reality." The CLIC collaboration published the Conceptual Design Report in 2012, and the key technology demonstration is in progress. The prospects for further advanced acceleration technology are briefly discussed for possible long-term future linear colliders.

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