Charge asymmetry in electron/positron energy loss in nuclear Bremsstrahlung

We calculate the leading Coulomb correction to the Bremsstrahlung energy loss in the electron-nucleus collisions for arbitrary energy of the incoming particle. This correction determines the charge asymmetry, i.e., the difference of electron and positron energy loss. The result is presented in terms of the classical polylogarithms Li2 and Li3. We use modern multiloop methods based on the IBP reduction and on the differential equations for master integrals. We provide both the threshold and the high-energy asymptotics of the found asymmetry and compare them with the available results.

Charge Asymmetry of Muons Generated by Laser- Induced Nuclear Processes in Ultra-dense Hydrogen D(0) and p(0)

Laser-induced nuclear reactions in ultra-dense hydrogen H(0) (review in Physica Scripta 2019) give mesons (kaons and pions) which decay to muons. The process which gives the mesons is baryon annihilation (Holmlid, J. Hydrogen Energy 2021; Holmlid and Olafsson, High Energy Density Phys. 2021). The sign of the muons detected depends on the initial baryons, with D(0) in the meson source producing mainly positive muons and p(0) producing mainly negative muons. This charge asymmetry was reported in Holmlid and Olafsson (Heliyon 2019), and has been confirmed by later experiments with a coil current transformer as beam detector , also in another lab (unpublished). The current coil detector would give no signal from the muons if charge symmetry existed. The charge asymmetry of the muons seems first to be at variance with charge conservation. An analysis of the results which includes charge conservation is given here. It agrees with the standard model of particle physics. Using D(0), the asymmetry is, as previously, proposed to be due to capture of µ- in D atoms and D2 molecules. This gives emission of mainly µ+ and a fraction of > 50% of µ+ from D(0). In p(0), the capture rate of µ- is lower than in D(0). The emitted number of µ+ will be decreased by reaction between µ+ and abundant electrons, forming muonium particles. This effect decreases the fraction of emitted µ+ for both p(0) and D(0), and it is proposed to be the main reason for a larger fraction of emitted µ- in the case of p(0).

Photoelectric and Magnetic Properties of Boron Nitride Nanosheets with Turbostratic Structure and Oxygen Doping

Turbostratic and oxygen doping (3.7 atom % ) hexagonal boron nitride nanosheets (TO-BNNSs) with abundant defect sites, were synthesized by pyrolyzing the mixture of melamine cyanurate and boric acid. Systematic analyses reveal a highly disordered structures and covalent oxygen-doping in the TO-BNNSs. These features endow the product with increased unpaired electrons, localized charge asymmetry and spin polarization. While compared with bulk h-BN, the optical bandgap of TO-BNNSs drop down to ~5.2 from ~5.7 eV, dielectric constant raised from ~2.1 to ~2.4, the saturation magnetic moment increased from ~0.011 to ~0.033 emu/g, and the coercivity enlarged from ~73.56 to ~367.39 Oe. These results suggest that h-BN materials with turbostratic structure and heteroatom-doping have extensive application prospect in the fields of nanoscale optics, electronics and magnetics.

Physics Formalism Helmholtz Matrix to Coulomb Gage

Iyer Markoulakis Helmholtz Hamiltonian mechanics formalisms mathematically modeled physics with vortex rotational fields acting with gradient fields, typically in zero-point microblackhole general fields. Here, Helmholtz metrics have been gaged to Coulombic Hilbert metrics, representing Gilbertian and Amperian natures of electromagnetic fields out of the mechanical fields from Helmholtz Hamiltonian mechanics. This ansatz general gaging helps to properly isolate field effects – mechanical, electric, magnetic components within the analytical processes. Vacuum gravitational fields and the flavor Higgs-Boson matter inertial gravitational fields have been thus quantified extending to stringmetrics constructs matrix showing charge asymmetry gage metrics, having the power to analyze dark energy superluminal phase, dark matter luminal phase, and light matter subluminal phase. Interpreting particle physics gage matrix pointing to Dirac seas electrons, monopoles with positrons, electron-positron annihilation leading to energy production, relativistic energy generating matter, and both monopoles – vacuum and compressed out of vortex Helmholtz decomposition fields have been interpolated. Quantum ASTROPHYSICS gage metrix posits superluminal profile of signals velocity generating electron-positron chain like “curdling” action that is consistent with physics literature reporting nature electron photon observed oscillatory fields configurations. This helps proposing creation of neutrino antineutrino pair orthogonal to electron positron “curdling” planes, that may lead to formation of protonic hydrogen of stars or orthogonally muon. These aspects will explain receding or fast expanding universe with dark matter in terms of flavor metrics versus gage associating metrics flavor. Additional interpretations of virtual gravitational dipoles that have gravitational charge of opposite signs, reported per physics literature at Planck dimensions, that may originate at the center of supermassive blackhole. On the other hands, vacuum monopoles occur probably at infinity with cosmos extent.

NLO QCD corrections to off-shell $${t{\bar{t}}W^\pm }$$ production at the LHC: correlations and asymmetries

Recent discrepancies between theoretical predictions and experimental data in multi-lepton plus b-jets analyses for the $$t{\bar{t}}W^\pm $$ t t ¯ W ± process, as reported by the ATLAS collaboration, have indicated that more accurate theoretical predictions and high precision observables are needed to constrain numerous new physics scenarios in this channel. To this end we employ NLO QCD computations with full off-shell top quark effects included to provide theoretical predictions for the $$\mathcal{R}= \sigma _{t{\bar{t}}W^+}/\sigma _{t{\bar{t}}W^-}$$ R = σ t t ¯ W + / σ t t ¯ W - cross section ratio at the LHC with $$\sqrt{s}=13$$ s = 13 TeV. Depending on the transverse momentum cut on the b-jet we obtain 2–3% theoretical precision on $$\mathcal{R}$$ R , which should help to shed some light on new physics effects that can reveal themselves only once sufficiently precise Standard Model theoretical predictions are available. Furthermore, triggered by these discrepancies we reexamine the charge asymmetry of the top quark and its decay products in the $$t{\bar{t}}W^\pm $$ t t ¯ W ± production process. In the case of charge asymmetries, that are uniquely sensitive to the chiral nature of possible new physics in this channel, theoretical uncertainties below 15% are obtained. Additionally, the impact of the top quark decay modelling is scrutinised by explicit comparison with predictions in the narrow-width approximation.

Antimatter Free-Fall Experiments and Charge Asymmetry

We propose a method by which one could use modified antimatter gravity experiments in order to perform a high-precision test of antimatter charge neutrality. The proposal is based on the application of a strong, external, vertically oriented electric field during an antimatter free-fall gravity experiment in the gravitational field of the Earth. The proposed experimental setup has the potential to drastically improve the limits on the charge-asymmetry parameter ϵ¯q of antimatter. On the theoretical side, we analyze possibilities to describe a putative charge-asymmetry of matter and antimatter, proportional to the parameters ϵq and ϵ¯q, by Lagrangian methods. We found that such an asymmetry could be described by four-dimensional Lorentz-invariant operators that break CPT without destroying the locality of the field theory. The mechanism involves an interaction Lagrangian with field operators decomposed into particle or antiparticle field contributions. Our Lagrangian is otherwise Lorentz, as well as PT invariant. Constraints to be derived on the parameter ϵ¯q do not depend on the assumed theoretical model.

Testing leptoquark/EFT in $${\bar{B}} \rightarrow {D^{(*)}}l{\bar{\nu }}$$ at the LHC

We investigate the current LHC bounds on New Physics (NP) that contributes to $${\bar{B}} \rightarrow {D^{(*)}}l{\bar{\nu }}$$ B ¯ → D ( ∗ ) l ν ¯ for $$l = (e,\mu ,\tau )$$ l = ( e , μ , τ ) by considering both leptoquark (LQ) models and an effective-field-theory (EFT) Hamiltonian. Experimental analyses from $$l+\text {missing}$$ l + missing searches with high $$p_T$$ p T are applied to evaluate the NP constraints with respect to the Wilson coefficients. A novel point of this work is to show difference between LQs and EFT for the applicable LHC bound. In particular, we find that the EFT description is not valid to search for LQs with the mass less than $$\lesssim 10\,\text {TeV}$$ ≲ 10 TeV at the LHC and leads to overestimated bounds. We also discuss future prospects of high luminosity LHC searches including the charge asymmetry of background and signal events. Finally, a combined summary for the flavor and LHC bounds is given, and then we see that in several NP scenarios the LHC constraints are comparable with the flavor ones.

Topping-up multilepton plus b-jets anomalies at the LHC with a Z′ boson

During the last years ATLAS and CMS have reported a number of slight to mild discrepancies in signatures of multileptons plus b-jets in analyses such as $$ t\overline{t}H $$ t t ¯ H , $$ t\overline{t}{W}^{\pm } $$ t t ¯ W ± , $$ t\overline{t}Z $$ t t ¯ Z and $$ t\overline{t}t\overline{t} $$ t t ¯ t t ¯ . Among them, a recent ATLAS result on $$ t\overline{t}H $$ t t ¯ H production has also reported an excess in the charge asymmetry in the same-sign dilepton channel with two or more b-tagged jets. Motivated by these tantalizing discrepancies, we study a phenomenological New Physics model consisting of a Z′ boson that couples to up-type quarks via right-handed currents: $$ {t}_R{\gamma}^{\mu }{\overline{t}}_R $$ t R γ μ t ¯ R , $$ {t}_R{\gamma}^{\mu }{\overline{c}}_R $$ t R γ μ c ¯ R , and $$ {t}_R{\gamma}^{\mu }{\overline{u}}_R $$ t R γ μ u ¯ R . The latter vertex allows to translate the charge asymmetry at the LHC initial state protons to a final state with top quarks which, decaying to a positive lepton and a b-jet, provides a crucial contribution to some of the observed discrepancies. Through an analysis at a detector level, we select the region in parameter space of our model that best reproduces the data in the aforementioned $$ t\overline{t}H $$ t t ¯ H study, and in a recent ATLAS $$ t\overline{t}t\overline{t} $$ t t ¯ t t ¯ search. We find that our model provides a better fit to the experimental data than the Standard Model for a New Physics scale of approximately ∼500 GeV, and with a hierarchical coupling of the Z′ boson that favours the top quark and the presence of FCNC currents. In order to estimate the LHC sensitivity to this signal, we design a broadband search featuring many kinematic regions with different signal-to-background ratio, and perform a global analysis. We also define signal-enhanced regions and study observables that could further distinguish signal from background. We find that the region in parameter space of our model that best fits the analysed data could be probed with a significance exceeding 3 standard deviations with just the full Run-2 dataset.