The QCD corrections of the process h → ηbZ

2018 ◽  
Vol 33 (15) ◽  
pp. 1830008
Author(s):  
Rong-Fei Zhu ◽  
Tai-Fu Feng ◽  
Hai-Bin Zhang
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Quantum Chromodynamics ◽  
Branching Ratio ◽  
Tree Level ◽  
Relative Correction ◽  
Loop Level ◽  
The Standard Model ◽  
Key Parameter

We investigate the 125 GeV Higgs boson decay to a pseudoscalar quarkonium [Formula: see text] and [Formula: see text] boson. We calculate the quantum chromodynamics (QCD) one-loop corrections to the branching ratio of the process, [Formula: see text], both in the Standard Model (SM) and in the two Higgs double models (THDM). Adding the QCD one-loop corrections, the branching ratio of [Formula: see text] in the SM is [Formula: see text]. The relative correction of that QCD one-loop level relative to the tree level of [Formula: see text] is around 76% in the SM. Similarly, the relative correction in the THDM also can be around 75%. The key parameter, [Formula: see text], can affect the relative correction in the THDM.

scholarly journals Search for π0 decays to invisible particles

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
E. Cortina Gil ◽  
◽  
A. Kleimenova ◽  
E. Minucci ◽  
S. Padolski ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Confidence Level ◽  
Branching Ratio ◽  
Standard Model Higgs Boson ◽  
Scalar Mixing ◽  
Upper Limit ◽  
Upper Limits ◽  
The Standard Model ◽  
Model Independent

Abstract The NA62 experiment at the CERN SPS reports a study of a sample of 4 × 109 tagged π0 mesons from K+ → π+π0(γ), searching for the decay of the π0 to invisible particles. No signal is observed in excess of the expected background fluctuations. An upper limit of 4.4 × 10−9 is set on the branching ratio at 90% confidence level, improving on previous results by a factor of 60. This result can also be interpreted as a model- independent upper limit on the branching ratio for the decay K+ → π+X, where X is a particle escaping detection with mass in the range 0.110–0.155 GeV/c2 and rest lifetime greater than 100 ps. Model-dependent upper limits are obtained assuming X to be an axion-like particle with dominant fermion couplings or a dark scalar mixing with the Standard Model Higgs boson.

scholarly journals Higgs boson production cross-section measurements and their EFT interpretation in the $$4\ell $$ decay channel at $$\sqrt{s}=$$13 TeV with the ATLAS detector

2020 ◽  
Vol 80 (10) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Cross Section ◽  
Decay Channel ◽  
Branching Ratio ◽  
Proton Collision ◽  
Boson Production ◽  
Theory Approach ◽  
Higgs Boson Production ◽  
The Standard Model

AbstractHiggs boson properties are studied in the four-lepton decay channel (where lepton = e, $$\mu $$ μ ) using 139 $$\hbox {fb}^{-1}$$ fb - 1 of proton–proton collision data recorded at $$\sqrt{s}=$$ s = 13 TeV by the ATLAS experiment at the Large Hadron Collider. The inclusive cross-section times branching ratio for $$H\rightarrow ZZ^*$$ H → Z Z ∗ decay is measured to be $$1.34 \pm 0.12$$ 1.34 ± 0.12  pb for a Higgs boson with absolute rapidity below 2.5, in good agreement with the Standard Model prediction of $$1.33 \pm 0.08$$ 1.33 ± 0.08  pb. Cross-sections times branching ratio are measured for the main Higgs boson production modes in several exclusive phase-space regions. The measurements are interpreted in terms of coupling modifiers and of the tensor structure of Higgs boson interactions using an effective field theory approach. Exclusion limits are set on the CP-even and CP-odd ‘beyond the Standard Model’ couplings of the Higgs boson to vector bosons, gluons and top quarks.

scholarly journals Quark-flavor-changing Higgs decays from a universal extra dimension

2020 ◽  
Vol 35 (24) ◽  
pp. 2050141
Author(s):  
Carlos M. Farrera ◽  
Alejandro Granados-González ◽  
Héctor Novales-Sánchez ◽  
J. Jesús Toscano
Keyword(s):  
Standard Model ◽  
Extra Dimension ◽  
New Physics ◽  
Tree Level ◽  
Universal Extra Dimension ◽  
Loop Level ◽  
Flavor Changing ◽  
The Standard Model ◽  
The One ◽  
Kaluza Klein

Kaluza–Klein fields characterizing, from a four-dimensional viewpoint, the presence of compact universal extra dimensions would alter low-energy observables through effects determined by some compactification scale, [Formula: see text], since the one-loop level, thus being particularly relevant for physical phenomena forbidden at tree level by the Standard Model. This paper explores, for the case of one universal extra dimension, such new-physics contributions to Higgs decays [Formula: see text], into pairs of quarks with different flavors, a sort of decay process which, in the Standard Model, strictly occurs at the loop level. Finite results, decoupling as [Formula: see text], are calculated. Approximate short expressions, valid for large compactification scales, are provided. We estimate that Kaluza–Klein contributions lie below predictions from the Standard Model, being about 2 to 3 orders of magnitude smaller for compactification scales within [Formula: see text].

scholarly journals 126 GeV HIGGS BOSON PAIR PRODUCTION AT THE LINEAR COLLIDER IN THE NONCOMMUTATIVE SPACE–TIME

2013 ◽  
Vol 28 (01) ◽  
pp. 1350004 ◽  
Author(s):  
PRASANTA KUMAR DAS ◽  
ABHISHODH PRAKASH
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Pair Production ◽  
Cross Section ◽  
Linear Collider ◽  
Noncommutative Space ◽  
Tree Level ◽  
Boson Pair ◽  
Boson Pair Production ◽  
The Standard Model

We study the 126 GeV Higgs boson pair production through e+e- collision in the noncommutative extension of the standard model using the Seiberg–Witten map of this to the first order of the noncommutative parameter Θμν. The process is forbidden in the standard model at the tree level. We study the time-averaged cross-section of the pair production at TeV scale linear collider and investigate the sensitivity of the cross-section on the orientation angle η and the noncommutative scale Λ. We found that Λ lies in the range 0.5 TeV–1.0 TeV, which can be reached by the upcoming linear collider.

scholarly journals (g − 2)μ versus K → π + Emiss induced by the (B − L)23 boson

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Zhaofeng Kang ◽  
Yoshihiro Shigekami
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
Neutral Current ◽  
Tree Level ◽  
Meson Decays ◽  
Loop Level ◽  
Flavor Changing ◽  
The Standard Model ◽  
Flavor Changing Neutral Current

Abstract To address the long-standing (g − 2)μ anomaly via a light boson, in ref. [1] we proposed to extend the standard model (SM) by the local (B − L)23, under which only the second and third generations of fermions are charged. It predicts an invisible Z′ with mass $$ \mathcal{O}(100) $$ O 100 MeV, and moreover it has flavor-changing neutral current (FCNC) couplings to the up-type quarks at tree level. Such a Z′, via KL→ π0 + Z′(→$$ v\overline{v} $$ v v ¯ ) at loop level, may be a natural candidate to account for the recent KOTO anomaly. In this article, we investigate this possibility, to find that Z′ can readily do this job if it is no longer responsible for the (g − 2)μ anomaly. We further find that both anomalies can be explained with moderate tuning of the CP violation, but may contradict the B meson decays.

scholarly journals Type-I 2HDM under the Higgs and electroweak precision measurements

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Ning Chen ◽  
Tao Han ◽  
Shuailong Li ◽  
Shufang Su ◽  
Wei Su ◽  
...  
Keyword(s):  
Standard Model ◽  
Higgs Doublet ◽  
New Physics ◽  
Higgs Bosons ◽  
Precision Measurements ◽  
Tree Level ◽  
Type I ◽  
Loop Level ◽  
The Standard Model ◽  
Parameter Ranges

Abstract We explore the extent to which future precision measurements of the Standard Model (SM) observables at the proposed Z-factories and Higgs factories may have impacts on new physics beyond the Standard Model, as illustrated by studying the Type-I Two-Higgs-doublet model (Type-I 2HDM). We include the contributions from the heavy Higgs bosons at the tree-level and at the one-loop level in a full model-parameter space. While only small tan β region is strongly constrained at tree level, the large tan β region gets constrained at loop level due to tan β enhanced tri-Higgs couplings. We perform a multiple variable χ2 fit with non-alignment and non-degenerate masses. We find that the allowed parameter ranges could be tightly constrained by the future Higgs precision measurements, especially for small and large values of tan β. Indirect limits on the masses of heavy Higgs bosons can be obtained, which can be complementary to the direct searches of the heavy Higgs bosons at hadron colliders. We also find that the expected accuracies at the Z-pole and at a Higgs factory are quite complementary in constraining mass splittings of heavy Higgs bosons. The typical results are | cos(β − α)| < 0.05, |∆mΦ| < 200 GeV, and tan β ≳ 0.3. The reaches from CEPC, Fcc-ee and ILC are also compared, for both Higgs and Z-pole precision measurements. Comparing to the Type-II 2HDM, the 95% C.L. allowed range of cos(β − α) is larger, especially for large values of tan β.

NON-STANDARD HIGGS BOSON AND THE DECAY KL→π0l+l−

1988 ◽  
Vol 03 (17) ◽  
pp. 1677-1682 ◽  
Author(s):  
M.I. DOBROLIUBOV ◽  
A. YU. IGNATIEV
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Branching Ratio ◽  
Branching Ratios ◽  
Upper Bounds ◽  
The Standard Model

We investigate various mechanisms of enhancement of the branching ratios of the decay KL→π0l+l− as compared to the predictions of the Standard Model. We propose a model with several Higgs doublets, which contains a Higgs boson with nearly equal couplings to e+e− and µ+µ− pairs. In this model, the branching ratio BR (KL→π0e+e−, π0µ+µ−) can be close to the present experimental upper bounds.

scholarly journals ALTERNATIVE IMPLEMENTATION OF THE HIGGS BOSON

2011 ◽  
Vol 26 (07) ◽  
pp. 461-467
Author(s):  
ROBERT FOOT ◽  
ARCHIL KOBAKHIDZE
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Gauge Invariance ◽  
Degrees Of Freedom ◽  
Energy Scale ◽  
Tree Level ◽  
Radiative Corrections ◽  
Gauge Bosons ◽  
The Standard Model ◽  
Low Energies

We discuss an alternative implementation of the Higgs boson within the Standard Model which is possible if the renormalizability condition is relaxed. Namely, at energy scale Λ the Higgs boson interacts at tree-level only with matter fermions, while the full gauge invariance is still maintained. The interactions with the electroweak gauge bosons are induced at low energies through the radiative corrections. In this scenario the Higgs boson can be arbitrarily heavy, interacting with the Standard Model fields arbitrarily weakly. No violation of unitarity in the scattering of longitudinal electroweak bosons occurs, since they become unphysical degrees of freedom at energies Λ ~ TeV.

Search for New Particles Decaying into $b \bar{b}$ Associated with W± Bosons at Tevatron

2005 ◽  
Vol 20 (15) ◽  
pp. 3294-3296
Author(s):  
◽  
Yoshio Ishizawa
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Cross Section ◽  
Production Cross ◽  
W Bosons ◽  
Branching Ratio ◽  
Standard Model Higgs Boson ◽  
Upper Limit ◽  
The Standard Model ◽  
New Particles

We present searches for new particles decaying into [Formula: see text] and produced in association with W± bosons in [Formula: see text] collisions at [Formula: see text]. The searches focus on the Standard Model Higgs boson or Technicolor particle decaying into [Formula: see text] using approximately 162 pb-1 of the dataset accumulated by the Collider Detector at Fermilab. The number of events and mass distribution are consistent with the Standard Model expectations and we set a 95% confidence level upper limit on the production cross section times branching ratio as a function of the new particle mass.

scholarly journals FURTHER STUDIES OF HIGGS PROPERTIES AT AN ILC γγ COLLIDER

2013 ◽  
Vol 28 (18) ◽  
pp. 1350085 ◽  
Author(s):  
XIAO-GANG HE ◽  
SIAO-FONG LI ◽  
HSIU-HSIEN LIN
Keyword(s):  
Angular Distribution ◽  
Higgs Boson ◽  
Standard Model ◽  
Decay Mode ◽  
Branching Ratio ◽  
Current Data ◽  
Decay Modes ◽  
The Standard Model ◽  
Shell Production

Recently the ATLAS and CMS experiments at the LHC have found a Higgs-like boson h with a mass around 125 GeV from several decay modes. The decay mode h →γγ is one of the most important modes in studying whether h is actually the Standard Model (SM) Higgs boson. Current data indicate that h→γγ has a branching ratio larger than the SM prediction for h being identified as the SM Higgs boson. To decide whether the h discovered at the LHC is the SM Higgs boson, more data are needed. We study how γγ collider can help to provide some of the most important information about the Higgs boson properties. We show that a γγ collider can easily verify whether the enhanced h →γγ observed at the LHC hold. Different models can be tested by studying Higgs boson decay to γZ. Studying angular distribution of the γγ through on-shell production of h and its subsequent decays into a γγ pair can decide whether the Higgs-like boson h at the LHC is a spin-0 or a spin-2 boson.

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