Radiative Corrections Research Articles

Reconciling LSND and Super-Kamiokande data through the dynamical Lorentz symmetry breaking in a four-Majorana fermion model

We propose a model of Majorana fermions with quartic self-couplings. These Majorana fermions acquire masses via a type II seesaw mechanism in which the physical eigenstates are identified as a light Majorana fermion and another heavy Majorana fermion. On a physical basis, the quartic self-couplings involve axial currents of these Majorana fermions, and also the interaction of the axial current for the light particle with the heavy particle one. We introduce two auxiliaries gauge fields in this model, and we study the stability conditions of the correspondent effective potential of the model. The ground state of the effective potential introduces two 4-vectors as scales of vacuum expected values, and consequently, the dynamical Lorentz symmetry breaking (DLSB) emerges in the model. We use the expansion of the effective action to calculate the effective Lagrangian up to second order in the auxiliary fields as fluctuations around the ground state. This mechanism generates dynamics for the auxiliary gauge fields, mixed mass terms, longitudinal propagation, and Chern-Simons term through radiative corrections. After the diagonalization, the two gauge fields gain masses through an analogous type II seesaw mechanism in which a gauge boson has a light mass, and the other one acquires a heavy mass. In this scenario of Lorentz symmetry breaking, we obtain the correspondent dispersion relations for the Majorana fermions and the gauge boson fields. Posteriorly, we analyze the neutrino's oscillations in the presence of a DLSB parameter, in the transition $\nu_{e} \rightarrow \nu_{\mu}$. We discuss the parameter space of this transition and show that the DLSB can conciliate the LSND and super-Kamiokande results.

Next-to-leading order corrections to decays of the heavier CP-even Higgs boson in the two Higgs doublet model

We investigate the impact of electroweak (EW), scalar and QCD corrections to the full set of decay branching ratios of an additional CP-even Higgs boson (H) in the two Higgs doublet model with a softly broken Z2 symmetry. We employ the improved gauge independent on-shell scheme in the renormalized vertices. We particularly focus on the scenario near the alignment limit in which couplings of the discovered 125 GeV Higgs boson (h) coincide with those of the standard model while the Hhh coupling vanishes at tree level. The renormalized decay rate for H→hh can significantly be changed from the prediction at tree level due to non-decoupling loop effects of additional Higgs bosons, even in the near alignment case. We find that the radiative corrections to the branching ratio of H→hh can be a few ten percent level in the case with the masses of additional Higgs bosons being degenerate under the constraints of perturbative unitarity, vacuum stability and the EW precision data. Further sizable corrections can be obtained for the case with a mass difference among the additional Higgs bosons.

Model-QED operator for superheavy elements

The model-QED-operator approach [Phys. Rev. A 88, 012513 (2013)] to calculations of the radiative corrections to binding and transition energies in atomic systems is extended to the range of nuclear charges $110 \leqslant Z \leqslant 170$. The self-energy part of the model operator is represented by a nonlocal potential based on diagonal and off-diagonal matrix elements of the ab initio self-energy operator with the Dirac-Coulomb wave functions. The vacuum-polarization part consists of the Uehling contribution which is readily computed for an arbitrary nuclear-charge distribution and the Wichmann-Kroll contribution represented in terms of matrix elements similarly to the self-energy part. Performance of the method is studied by comparing the model-QED-operator predictions with the results of ab initio calculations. The model-QED operator can be conveniently incorporated in any numerical approach based on the Dirac-Coulomb-Breit Hamiltonian to account for the QED effects in a wide variety of superheavy elements.

O(αs) perturbative and nonperturbative corrections to polarized semileptonic Λb decay distributions

In this paper we calculate first order radiative QCD corrections to the decay process $b\to cW^-(\to\ell^-\bar\nu_\ell)$ of a polarized bottom quark. Taking into account both the bottom and charm quark masses, the analytical expressions given in this paper allow for a detailed analysis of the differential decay rate of the polarized quark in dependence on the polar and azimuthal angles of the lepton pair and the angle of the polarization vector of the quark relative to the momentum direction of the $W$ boson. The results are given for different polarization states of the charged lepton. In addition, we calculated nonperturbative corrections and estimated their contribution.

Disentangling long and short distances in momentum-space TMDs

The extraction of nonperturbative TMD physics is made challenging by prescriptions that shield the Landau pole, which entangle long- and short-distance contributions in momentum space. The use of different prescriptions then makes the comparison of fit results for underlying nonperturbative contributions not meaningful on their own. We propose a model-independent method to restrict momentum-space observables to the perturbative domain. This method is based on a set of integral functionals that act linearly on terms in the conventional position-space operator product expansion (OPE). Artifacts from the truncation of the integral can be systematically pushed to higher powers in ΛQCD/kT. We demonstrate that this method can be used to compute the cumulative integral of TMD PDFs over {k}_Tle {k}_T^{mathrm{cut}} in terms of collinear PDFs, accounting for both radiative corrections and evolution effects. This yields a systematic way of correcting the naive picture where the TMD PDF integrates to a collinear PDF, and for unpolarized quark distributions we find that when renormalization scales are chosen near {k}_T^{mathrm{cut}} , such corrections are a percent-level effect. We also show that, when supplemented with experimental data and improved perturbative inputs, our integral functionals will enable model-independent limits to be put on the non-perturbative OPE contributions to the Collins-Soper kernel and intrinsic TMD distributions.

Impact of radiative heat flux on turbine blade heat transfer in high temperature environments

• A theoretical method for determining heat radiation on turbine vanes is proposed. • The contribution of radiation to total heat flux is distinguished and calculated. • Calculation is simplified via a radiation coefficient based on multiple parameters. • Emissivity measurements, which are normally tedious to obtain, are not necessary. • The proposed method was validated via numerical calculations. The efficient cooling technology used in first-stage turbine vanes results in a large temperature difference between the blade wall and high-temperature gas. The resulting thermal radiation cannot be neglected. However, in experimental environments, it is impossible to accurately assess the effects of radiation. In this study, a novel, simplified version of an existing experimental method is proposed, to distinguish the radiation from the total heat flux; it uses blade wall-temperature measurements and ternary nonlinear regression. The results show that when the mainstream temperature is 1000–1300 K and the cold air temperature is 550–750 K ( T ∞ / T cold > 2.5), the radiative heat flux accounts for 15–20% of the total heat flux (when the gas composition is pure air). In real working conditions ( T ∞ / T cold ≈ 2.2), the radiative heat flux cooled without an air film accounts for 11.96–14.4% of the total heat flux. When the gas includes radiation-participating media (e.g., CO 2 and H 2 O), the radiative heat flux accounts for 21.4–22.72% of the total heat flux. The effects of radiation cannot be neglected in studies considering the heat transfer of turbine blades. In addition, the radiation correction factor is defined to comprehensively account for the effects of radiation. Under real conditions ( T ∞ / T cold ≈ 2.2), the radiation correction factor is 1.275. Finally, the simplified approach is validated using numerical calculations.

Complete theory of radiative corrections to Kℓ3 decays and the Vus update

We fill up the missing piece in our own re-analysis of the long-distance electromagnetic radiative corrections to semileptonic kaon decays by performing a rigorous study in the K → πμ+νμ(γ) channels. With appropriate experimental and lattice inputs, we achieve a precision level of 10−4 in these channels. This is comparable to our previous analysis in the K → πe+νe(γ) channels. With this new result, we present an updated global analysis to extract the Standard Model parameter |Vus| from semileptonic kaon decays. We obtain |Vus| = 0.22308(55) and 0.22356(73), using the lattice average of the K0→ π− transition form factor at Nf = 2 + 1 + 1 and Nf = 2 + 1, respectively.

Estimating land surface temperature to study land use land cover influence on the temperature in a city with a dry arid climate

Turning arid regions or forests into urban areas (Urbanization) is affecting the global temperature. This effect is intensifying due to uncontrolled urban growth. To understand the influence of land use land cover (LULC) on land surface temperature (LST) in dry arid climate cities like Sharjah, UAE, 2 Landsat 8 images were used to retrieve the LST, one in summer and one in winter by using the radiation correction equation in google earth engine. Supervised classification of a high-resolution image from worldview-3 will produce the LULC map. In addition, hourly ground temperature data (GT) is retrieved from 6 field stations to validate LST and find the correlation if it exists. The LST images were then compared to the different LULC, to find relationships between the two. This study showed that barren soil experienced the highest LST when compared to vegetation and urban areas, and vegetation areas experienced the lowest temperatures compared to all other LULC, finally, urbanization that was combined with green lands can have a positive impact on the temperature in cities with dry arid climates. This study proves that understanding the effects of urbanization on temperature accurately will aid greatly in the future planning of cities.

Purely radiative Higgs mass in scale invariant models

In this work, we investigate the possibility of having scale invariant (SI) standard model (SM) extensions, where the light CP-even scalar matches the SM-like Higgs instead of being a light dilaton. After deriving the required conditions for this scenario, we show that the radiative corrections that give rise to the Higgs mass can trigger the scalar mixing to the experimentally allowed values. In addition, we discuss the constraints on the parameters space that makes the CP-even scalars properties in a good agreement with all the recent ATLAS and CMS measurements. We illustrate this scenario by considering the SI-scotogenic model as an example, while imposing all the theoretical and experimental constraints. We show that the model is viable and leads to possible modifications of the di-Higgs signatures at current/future with respect to the SM.

Pair production of neutral Higgs particles in the B-LSSM

Higgs pair production provides a unique handle for measuring the strength of Higgs self interaction and constraining the shape of the Higgs potential. Including radiative corrections to the trilinear couplings of CP-even Higgs, we investigate the cross section of the lightest neutral Higgs pair production in gluon fusion at the Large Hadron Collider in the supersymmetric extensions of the standard model. Numerical results indicate that the correction to the cross section is about 11% in the B-LSSM, while is only about 4% in the MSSM. Considering the constraints of the experimental data of the lightest Higgs, we find that the gauge couplings of U(1) B–L and the ratio of the nonzero vacuum expectation values of two singlets also affect strongly the theoretical evaluations on the production cross section in the B-LSSM.

Full electroweak 𝒪(α) corrections to Higgs-boson production processes with beam polarization at the International Linear Collider

Abstract We present the full ${{\cal O}}(\alpha )$ electroweak radiative corrections to the production of nine Higgs bosons with beam polarization at the International Linear Collider (ILC). The computation is performed with the help of GRACE-Loop. We compare the full ${{\cal O}}(\alpha )$ electroweak radiative corrections with the factorized initial-state radiation (ISR) effects to estimate the pure weak corrections. This reveals that the pure weak corrections are not negligible and should be taken into account for precision measurements of the Higgs-boson property at the ILC experiments.

EW radiative corrections to theory predictions of charge asymmetry for W-boson hadroproduction

The higher-order predictions of the lepton charge asymmetry (the W-boson charge asymmetry ) for the leptonic final state of the W-boson hadroproduction in proton–proton (pp) collisions are presented. The predictions from the state-of-the-art computations are reported for achieving adequate description of the by including next-to-leading order (NLO) electroweak (EW) radiative corrections in combination with next-to-NLO (NNLO) quantum chromodynamics (QCD) radiative corrections. The combined predictions NNLO QCD+NLO EW and NNLO QCD × NLO EW, based on standard additive and factorised combination prescriptions in turn, are provided in the fiducial phase space of the pseudorapidity of the decay lepton (of the rapidity of the W-boson), comprising both central and forward detector acceptance regions as η l ≤ 4.5 (y W ≤ 4.5). The inclusion of the NLO EW effects for the () constitutes additional input for the relative u- and d-quark densities in the proton, which is also of high importance in the domain of the high-precision studies. The predicted distributions are compared with the actual measurements by CERN Large Hadron Collider (LHC) experiments at 8 TeV pp collisions energies. The combined predictions for the () distributions are also provided in comparisons with the NNLO QCD predictions at both 13 TeV and 14 TeV energies. The impact of the NLO EW corrections for the () distributions is extensively assessed by means of relative correction factor analysis with respect to the NNLO QCD predictions, in addition to a detailed K-factor analysis with respect to the leading order (LO) accuracy. The predicted results show that the NLO EW effects have larger impact in the forward η l region of the contrary to the central η l region, and is sizable in some of the y W ranges of the . The paper suggests inclusion of the presented EW corrections at NLO to have explicit accounting for the EW effects for the () in phenomenological studies.

Background field method and generalized field redefinitions in effective field theories

We study the non-linear background field redefinitions arising at the quantum level in a spontaneously broken effective gauge field theory. The non-linear field redefinitions are crucial for the symmetric (i.e. fulfilling all the relevant functional identities of the theory) renormalization of gauge-invariant operators. In a general R_\xiRξ-gauge the classical background-quantum splitting is also non-linearly deformed by radiative corrections. In the Landau gauge these deformations vanish to all orders in the loop expansion.

New developments in KKMChh: Quark-level exponentiated radiative corrections and semi-analytical results

We describe a new semi-analytical program, KKhhFoam, which provides a simplified framework for testing the amplitude-level exponentiation scheme (CEEX) of the full KKMChh program in the semi-soft limit. The structure of the KKhhFoam integrand is also helpful for elucidating the structure of CEEX. We also discuss the representation of ISR in KKMChh and compare the ISR added by KKMChh to the effect of switching to a QED-corrected PDF, at the individual quark level, and suggest a new approach to running KKMChh with QED-corrected PDFs.

New and old physics in the interaction of a radiating electron with the extreme electromagnetic field

We show that an all-optical configuration of the laser-electron collision in the ${\ensuremath{\lambda}}^{3}$ configuration based on 10 PW-class lasers presents a viable platform for reaching the range of parameters where a perturbative QED in strong external electromagnetic field breaks. This case is contingently referred to as a case of the nonperturbative QED, and this range of parameters is the intriguing goal from an experimental point of view because of a possible manifestation of a new physics of the interaction of a highly radiating particle with a strong electromagnetic field. We show that the strong-field region can be reached by electrons having initial energy higher than 50 GeV. Our theoretical considerations are in agreement with three-dimensional particle-in-cell simulations. While increasing of the electron energy raises the number of electrons experiencing the strong-field region, the observable signature of photon emission radiative correction in the strong field is expected to fade out when the electron energy surpasses the optimal value. This threshold of electron energy is identified and the parameters for achieving the nonperturbative limit of QED are provided.

Validation and bias correction of incoming solar radiation from two reanalysis products over India

Validation and bias correction of incoming solar radiation from two reanalysis products over India

Singlet-doublet fermion origin of dark matter, neutrino mass and W-mass anomaly

Motivated by the recently reported anomaly in W boson mass by the CDF collaboration with 7σ statistical significance, we consider a singlet-doublet (SD) Majorana fermion dark matter (DM) model where the required correction to W boson mass arises from radiative corrections induced by SD fermions. While a single generation of SD fermions, odd under an unbroken Z2 symmetry, can not explain the W boson mass anomaly while being consistent with DM phenomenology, two generations of SD fermions can do so with the heavier generation playing the dominant role in W-mass correction and lighter generation playing the role in DM phenomenology. Additionally, such multiple generations of SD fermions can also generate light neutrino masses radiatively if a Z2-odd singlet scalar is included.

Numerical analysis of the self-energy in covariant loop quantum gravity

We study numerically the first order radiative corrections to the self-energy, in covariant loop quantum gravity. We employ the recently developed 'sl2cfoam-next' spinfoam amplitudes library, and some original numerical methods. We analyze the scaling of the divergence with the infrared cutoff, for which previous analytical estimates provided widely different lower and upper bounds. Our findings suggest that the divergence is approximately linear in the cutoff. We also investigate the role of the Barbero-Immirzi parameter in the asymptotic behavior, the dependence of the scaling on some boundary data and the expectation values of boundary operators.

The τ → ντπe+e − decay revisited

The recent results from Belle of the τ − → ντπ −e +e − analysis have incentivated us to make a reanalysis of a former work where the Structure Dependent parts are obtained using Resonance Chiral Theory. Here we rely on the same theory accounting for effects that explicitly break such symmetry. A motivation is the involved W πγ? vertex, utterly relevant in computing τ − → ντπ − radiative corrections.

Radiative correction to lepton proton scatterings in manifestly Lorentz-invariant chiral perturbation theory

Manifestly lorentz-invariant baryon chiral perturbation theory is used to calculate the radiative correction of low energy elastic lepton proton scatterings. Corrections of differential cross section and charge asymmetry are given at next-to-leading order with nonzero lepton mass, in which both are infrared and ultraviolet finite. The results are basically consistent with previous predictions based on hadron model, but somewhat different from calculations based on heavy baryon chiral perturbation theory, especially in charge asymmetry.