Towards a measurement of the two-photon decay width of the Standard Model Higgs boson at a Photon Collider

A study of the measurement of the two photon decay width times the branching ratio of the Standard Model Higgs boson with a mass of 120 GeV in photon–photon collisions is presented, assuming a γ γ integrated luminosity of 80 fb⁻¹ in the high energy part of the spectrum. The analysis is based on the reconstruction of the Higgs events produced in the γ γ→H process, followed by the decay of the Higgs into a pair. A statistical error of the measurement of the two-photon width, Γ(H→γ γ), times the branching ratio of the Higgs boson, BR is found to be 2.1% for one year of data taking.     

Probing the Lightest New Gauge Boson BH in the Littlest Higgs Model via Processes γγ→ ff^- Bg at ILC

The neutral gauge boson BH with the mass of hundreds GeV is the lightest particle predicted by the littlest Higgs （LH） model, and such particle should be the first signal of the LH model at the planed ILC if it exists indeed. In this paper, we study some processes of the BH production associated with the fermion pair at the ILC, i.e., γγ→ ff^- BH. The studies show that the most promising processes to detect BH amongγγ→ ff^- BH are γγ→ l＇^＋l＇^-BH （l＇ = e,μ）, and they can produce the sufficient signals in most parameter space preferred by the electroweak precision data at the ILC. On the other hand, the signal produced via the certain BH decay modes is typical and such signal can be easily identified from the SM background. Therefore, BH, the lightest gauge boson in the LH model, would be detectable at the photon collider realized at the ILC.     

Observation of the Higgs Boson of strong interaction via Compton scattering by the nucleon

It is shown that the Quark-Level Linear σ Model (QLLσM) leads to a prediction for the diamagnetic term of the polarizabilities of the nucleon which is in excellent agreement with experimental data. The bare mass of the σ meson is predicted to be m _σ =666 MeV and the two-photon width Γ(σ→γ γ)=(2.6±0.3) keV. It is argued that the mass predicted by the QLLσM corresponds to the $\gamma\gamma\to\sigma\to N\bar{N}$ reaction, i.e. to a t-channel pole of the γ N→N γ reaction. Large-angle Compton scattering experiments revealing effects of the σ meson in the differential cross section are discussed. Arguments are presented that these findings may be understood as an observation of the Higgs boson of the strong interaction while being a part of the constituent quark.     

Energy-Momentum of a Cosmological Brane Model and the Gauge Hierarchy

We analyze in this paper the general covariant energy-momentum tensor of the gravitational system in general five-dimensional cosmological brane-world models. Then through calculating this energy-momentum for the cosmological generalization of the Randall-Sundrum model, which includes the original RS model as the static limit, we are able to show that the weakness of the gravitation on the “visible” brane is a general feature of this model. This is the origin of the gauge hierarchy from a gravitational point of view. Our results are also consistent with the fact that a gravitational system has vanishing total energy.     

Axion-Like Particles and the Higgs Decays h→PZ and h→Pe~+e~-

Axion-like particles(ALPs)are often defined as relatively light pseudoscalar particles and appear in many extensions of the Standard Model.Taking into account constraints on the free parameters from existing searches and explaining the g-2 deviation,we consider the contributions of ALPs with mass in the range of 1.5GeVm_am_h-m_Z to the exclusive Higgs decays h→PZ and h→Pe~+e~-with P being the pseudoscalar mesonsπ~0,η,η',η_c andη_b in a model-independent approach.We find that,in most of the parameter space range,the contributions of ALP to these decay-processes are ver.y small,while in the case of the ALP mass ma approximatel.y equaling the meson mass m_P,the contributions are significantly large.     

Measurement of the Coupling Constant of the Higgs Boson with a tt ¯ $$ overline{tt} $$ Heavy Quark Pair

Russian Physics Journal - The process of production of a Higgs boson HSM of the Standard Model (the H , h , and A bosons of the Minimal Supersymmetric Standard Model) and a $$ overline{tt} $$...     

A Study of the Standard Model Higgs Boson in the H → WW* → ��ν��ν Decay Channel in the ATLAS Experiment at the LHC

Physics of Atomic Nuclei - The authors within the Higgs Boson Working Group of the ATLAS experiment at the LHC performed an analysis of events with two leptons and two hadron jets to study Standard...     

A Study of the Charm-Baryonic Structure from ㄚ Decays

In the framework of perturbative QCD,the exclusive decays $\Upsilon\to B\bar B$(B:baryon) are studied.With the constituent quark model describing the charm-baryonic structure, we calculate the decay widths for $\Upsilon\to p\bar p,\Lambda_c\bar \Lambda_c,\Sigma_c\bar \Sigma_c,\Xi_c\bar \Xi_c,\Xi_{cc}^+\Xi_{cc}^-,\occc\bar \occc $ , and discuss the prospect to search for the charm baryon $\occc$ in $\Upsilon$ decays.     

B→ηK and B→φKs Decays in the Two Higgs Doublet Model Ⅲ

Using the QCD factorization approach, we investigate the large branching ratios of B→ηK^＊ decays and the SCKs anomaly of B→φKs decay in the two Higgs doublet model Ⅲ. With the contributions of flavour-changing neutral current mediated by the neutral Higgs bosons H^0, h^0 and A^0 at the tree level, we provide a coherent resolution to these anomalies within the constrained parameter spaces, which are 120 〈｜λbs λss｜ 〈136. This will be really interesting in searching for the signs of new physics.     

Development of the Fast Ionization Gauge in a Strong Magnetic Field

The neutral gas pressure near plasma or divertor plates are very important for the plasma-wall interaction, which determines the operating mode of divertor and confining performances of plasma in tokamaks. A fast ionization gauge (fast gauge) is designed for this purpose in the HL-2A tokamak.     

Geometrization of the Gauge Connection within a Kaluza–Klein Theory

We geometrize a generic (abelian and non-abelian) gauge coupling within the framework of a Kaluza–Klein theory, by choosing a suitable matter-field dependence on the extra coordinates. We first extend the Nöther theorem to a multidimensional spacetime, the Cartesian product of a 4-dimensional Minkowski space and a compact homogeneous manifold (whose isometries reflect the gauge symmetry). On such a “vacuum” configuration, the extra-dimensional components of the field momentum correspond to the gauge charges. Then we analyze the structure of a Dirac algebra for a spacetime with the Kaluza–Klein restrictions. By splitting the corresponding free-field Lagrangian, we show how the gauge coupling terms arise.     

Variations of the Speed of Light with Frequency and Implied Photon Mass

A general frequency-dependent dispersion relation of the speed of light in different mediums （vacuum, insulator, plasma） is deduced based on the Proca equations. Several recent astronomical observations of the pulsars are used to set the limits on the photon rest mass by this method and several upper bounds of larger than one order improvement than previous similar results are obtained. Considering the dispersion of the massive photon, the possible upper limits on the photon rest mass are also derived from the recently experimental results for testing the constancy of the speed of light in special relativity.     

Exact Calculations of Vertex ^-sγb and ,^-sZb in the Unitary Gauge

In this paper, we present the exact calculations for the vertex ^-sγb and ^sZb in the unitary gauge. We find that （a） the divergent- and μ-dependent terms are left in the effective vertex function Г^γμ（p, k） for b → sγ transition even after we sum up the contributions from four related Feynman diagrams; （b） for an on-shell photon, such terms do not contribute et al.; （c） for off-shell photon, these terms will be canceled when the contributions from both vertex ^sγb and ^sZb are taken into account simultaneously, and therefore the finite and gauge-independent function Zo（xt） = Co（xt） ＋ Do（xt）/4, which governs the semi-leptonic decay b → sl^- l^＋, is derived in the unitary gauge.     

Study of Events with Two Leptons in the Final State to Investigate Properties of the Standard Model Higgs Boson and Search for a Heavy Higgs Boson in the h/H → WW(*) → ��ν��ν Decay in pp Collisions at 13 TeV with the ATLAS Detector at the LHC

Physics of Atomic Nuclei - The authors, members of the ATLAS Higgs boson working group (HWW), studied events with two leptons in the...     

Study of ψ(2S)Decays into pπ and KK

From a study of(2S)decays into vector-pseudoscalar final states,ρπ and KK*,based on a sample of 1.27×10⁶ produced (2S) events,we have set upper limits at 90% confidence level on the branching fractions into ρπof 3.6×10^－5, into K⁺K^*+c.c.of 2.5×10^－5,and into K⁰K^*0+c.c.of 1.2×10^－4.We find that all these decays are substantially suppressed relative to the corresponding J/ψ decays in comparison with PQCD predictions.Our results confirm the MARK Ⅱ measurements at an improved sensitivity level.     

Detection of Charged Higgs Bosons in e~+e~-(γγ)→tφ~- Production at the ILC

In the context of the left-right twin Higgs (LRTH) model,we have studied the charged Higgs bosons production processes e~+e~-(γγ)→tφ~at the International Linear Collider (ILC).It is found that the cross sections of these two processes could reach a few fb with reasonable parameter values.With the yearly integrated luminosity of L=500 fb-1 expected at the ILC,one could collect hundreds up to thousands of charged Higgs events via these two processes.Therefore,our researches in this paper can help us search for charged Higgs bosons,and furthermore,to test the LRTH model.