Percent Level Research Articles

A non-parametric approach to the relation between the halo mass function and internal dark matter structure of haloes

Context. Galaxy cluster masses are usually defined as the mass within a spherical region enclosing a given matter overdensity (in units of the critical density). Converting masses from one overdensity definition to another can have several useful applications. Aims. In this article we present a generic non-parametric formalism that allows one to accurately map the halo mass function between two different mass overdensity definitions using the distribution of halo sparsities defined as the ratio of the two masses. We show that changing mass definitions reduces to modelling the distribution of halo sparsities. Methods. Using standard transformation rules of random variates, we derive relations between the halo mass function at different overdensities and the distribution of halo sparsities. Results. We show that these relations reproduce the N-body halo mass functions from the Uchuu simulation within the statistical errors at a few percent level. Furthermore, these relations allow the halo mass functions at different overdensities to be related to parametric descriptions of the halo density profile. In particular, we discuss the case of the concentration-mass relation of the Navarro-Frenk-White profile. Finally, we show that the use of such relations allows us to predict the distribution of sparsities of a sample of haloes of a given mass, thus opening the way to inferring cosmological constraints from individual galaxy cluster sparsity measurements.

Prospects of testing late-time cosmology with weak lensing of gravitational waves and galaxy surveys

We investigate the synergy of upcoming galaxy surveys and gravitational wave (GW) experiments in constraining late-time cosmology, examining the cross-correlations between the weak lensing of gravitational waves (GW-WL) and the galaxy fields. Without focusing on any specific GW detector configuration, we benchmark the requirements for the high precision measurement of cosmological parameters by considering several scenarios, varying the number of detected GW events and the uncertainty on the inference of the source luminosity distance and redshift.We focus on ΛCDM and scalar-tensor cosmologies, using the Effective Field Theory formalism as a unifying language. We find that, in some of the explored setups, GW-WL contributes to the galaxy signal by doubling the accuracy on non-ΛCDM parameters, allowing in the most favourable scenarios to reach even percent and sub-percent level bounds. Though the most extreme cases presented here are likely beyond the observational capabilities of currently planned individual GW detectors, we show nonetheless that — provided that enough statistics of events can be accumulated — GW-WL offers the potential to become a cosmological probe complementary to LSS surveys, particularly for those parameters that cannot be constrained by other GW probes such as standard sirens.

Mixing effects of η−η′ in Λb→Λη(′) decays

We perform a thorough analysis of the $\eta-\eta'$ mixing effects on the $\Lambda_b\rightarrow \Lambda \eta^{(')}$ decays based on the perturbative QCD (PQCD) factorization approach. Branching ratios, up-down and direct $CP$ asymmetries are computed by considering four popular mixing schemes, such as $\eta-\eta'$, $\eta-\eta'-\eta_c$, $\eta-\eta'-G$, and $\eta-\eta'-G-\eta_c$ mixing formalism, where $G$ represents the physical pseudoscalar gluball. The PQCD predictions with the four mixing schemes does not change much for the $\eta$ channel but changes significantly for the $\eta'$ one. In particular, the value of $\mathcal{B}(\Lambda_b\rightarrow \Lambda \eta^{'})$ in the $\eta-\eta'-G-\eta_c$ mixing scheme exceeds the present experimental bound by a factor of 2, indicates the related mixing angles may be overestimated. Because of the distinctive patterns of interference between $S$-wave and $P$-wave amplitudes, the predicted up-down asymmetries for the two modes differ significantly. The obvious discrepancies among different theoretical analyses should be clarified in the future. The direct $CP$ violations are predicted to be at the level of a few percent mainly due to the tree contributions of the strange and nonstrange amplitudes suffer from the color suppression and CKM suppression. Finally, as a byproduct, we investigate the $\Lambda_b\rightarrow \Lambda \eta_c$ process, which has a large branching ratio of order $10^{-4}$, promising to be measured by the LHCb experiment. Our findings are useful for constraining the mixing parameters, comprehending the $\eta^{(')}$ configurations, and instructing experimental measurements.

Four-loop splitting functions in QCD – The quark-quark case

We have computed the even-N moments N≤20 of the pure-singlet quark splitting function Pps at the fourth order of perturbative QCD via the anomalous dimensions of off-shell flavour-singlet operator matrix elements. Our results, derived analytically for a general gauge group, agree with all results obtained for this function so far, in particular with the lowest six even moments obtained via physical cross sections. Using these results and all available endpoint constraints, we construct approximations for Pps at four loops that should be sufficient for most collider-physics applications. Together with the known results for the non-singlet splitting function Pns+ at this order, this effectively completes the quark-quark contribution for the evolution of parton distribution at N3LO accuracy. Our new results thus provide a major step towards fully consistent N3LO calculations at the LHC and the reduction of the residual uncertainty in the parton evolution to the percent level.

EFT analysis of New Physics at COHERENT

Using an effective field theory approach, we study coherent neutrino scattering on nuclei, in the setup pertinent to the COHERENT experiment. We include non-standard effects both in neutrino production and detection, with an arbitrary flavor structure, with all leading Wilson coefficients simultaneously present, and without assuming factorization in flux times cross section. A concise description of the COHERENT event rate is obtained by introducing three generalized weak charges, which can be associated (in a certain sense) to the production and scattering of νe, νμ and {overline{nu}}_{mu } on the nuclear target. Our results are presented in a convenient form that can be trivially applied to specific New Physics scenarios. In particular, we find that existing COHERENT measurements provide percent level constraints on two combinations of Wilson coefficients. These constraints have a visible impact on the global SMEFT fit, even in the constrained flavor-blind setup. The improvement, which affects certain 4-fermion LLQQ operators, is significantly more important in a flavor-general SMEFT. Our work shows that COHERENT data should be included in electroweak precision studies from now on.

Socio-economic Impacts of Water Project on the Community Livelihood in Peri-urban of Tanzania: Case study Gairo District – Morogoro Region

This study analyzed the socio-economic impacts of water projects on community livelihood in peri-urban Tanzania. It employed a cross-sectional research design, and a survey questionnaire was distributed to 353 households that were randomly selected by probability sampling procedures. Data were analysed using the logistic regression model. This study was guided by theory of Peri-Urban Turbulence (PUT) which is founded on the idea of changes in the balance and magnitude of natural and caused infrastructure and local and distant established arrangements during the transition, primarily in fast-growing urban areas of the Global South. The findings suggests the respondents’ year of schooling positively affect household access to water. Having one additional year of schooling may increase the chance to access to water facilities. Furthermore, the average household head’s monthly income was a significant explanatory variable at a one percent level of significance. Besides, non-farm activities were significantly associated to access to water. Nevertheless, the study identified the four major economic activities that the community engaged in as a result of water accessibility; male and female hair saloon salons, petty trading in village open auctions, vegetable gardening, and motorbike riding. Among of the four major economic activities performed, petty trading in the village open auction business is the most practiced. One can conclude that, the existence of water projects promotes socio- and economic development.

Higgs squared

We present a novel construction for a Higgs-VEV sensitive (HVS) operator, which can be used as a trigger operator in cosmic selection models for the electroweak hierarchy problem. Our operator does not contain any degrees of freedom charged under the SM gauge symmetries, leading to reduced tuning in the resulting models. Our construction is based on the extension of a two Higgs doublet model (2HDM) with a softly broken approximate global D8 symmetry (the symmetry group of a square). A cosmic crunching model based on our extended Higgs sector has only a percent level tuning corresponding to the usual little hierarchy problem. In large regions of parameter space the 2HDM is naturally pushed towards the alignment limit. A complete model requires the introduction of fermionic top partners to ensure the approximate D8 symmetry in the fermion sector. We also show that the same extended Higgs sector can be used for a novel implementation of the seesaw mechanism of neutrino masses.

Abrupt peaks in perceived risk of occasional drug use after changing the question order in a repeated self-administered survey.

Question-order changes in repeated surveys can distort comparisons. We want to describe the evolution of drug risk perceptions among Spanish adolescents and assessing whether the 2006 peaks in perceived risk of occasional drug use can be explained by question-order changes. The subjects were secondary students from a biennial national survey during 2000-2012. A one-off intervention was applied in 2006, replacing the two-adjacent items on perceived risk of occasional and regular use of each drug by non-adjacent items. Annual prevalence of high-risk perception were obtained for occasional and regular use of cannabis, heroin, cocaine and ecstasy. Subsequently, the 2006 percent level change (PC) in such were estimated prevalence using segmented Poisson regression, adjusting for various student and parent covariates. The 2006 PC in prevalence of high-risk perception of occasional drug use ranged from +63% (heroin) to +83% (ecstasy). These PCs were very high in all considered subgroups. However, the 2006 PC in prevalence of high-risk perception of regular drug use ranged from 1% (heroin) to 12% (cannabis). The evolution of preventive interventions does not suggest alternative causal hypotheses for 2006 peaks other than question-order changes. Within the cognitive heuristics framework, the 2006 spikes in perceived risk of occasional drug use were most likely due to a release of the anchor exerted by perceived risk of regular drug use over that of occasional use triggered by 2006 question-order changes. In repeated surveys it is inexcusable to pre-test the effect of any change in questionnaire format.

The Impact of Working Capital Management (WCM) on Firm’s Profitability: The Case of Cement Industry of Khyber Pakhtunkhwa (Pakistan)

In this study, researchers looked at how management working capital affected the profitability of manufacturing companies producing cement in Khyber Pakhtunkhwa, Pakistan. Our sample consisted of three manufacturing company’s registered on the Karachi Stock Exchange, and we examined their performance over a 12-year period from 2008 to 2020. Our primary independent variables were inventory turnover in days (ITID) and average collection period (ACP), while the dependent variables included return on equity (ROE) and net profit margin (NPM). To examine how management working capital and business performance are related, Studies employed panel data analysis techniques. Our findings suggest a positive influence of management working capital on firm profitability. Importantly, this association was found to be statistically importance at the 5 percent level, indicating that effective management of working capital contributes positively to shareholder value. Our study highlights the significant of sound management working capital practices in enhancing the performance of cement manufacturing companies in Khyber Pakhtunkhwa, Pakistan, ultimately benefiting their shareholders.

Estimates of exchange topological contributions and CP -violating observables in Λb→Λϕ decay

The penguin-dominated two-body weak decay of ${\mathrm{\ensuremath{\Lambda}}}_{b}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Lambda}}\ensuremath{\phi}$ is studied based on the perturbative QCD approach. In addition to the penguin emission diagrams, the penguin exchange and $W$ exchange ones are also accounted for. It is found that the penguin exchange contribution is in fact important and comparable to the penguin emission one, while the $W$ exchange contribution is highly Cabibbo-Kobayashi-Maskawa (CKM) suppressed. The predicted branching ratio, $\mathcal{B}({\mathrm{\ensuremath{\Lambda}}}_{b}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Lambda}}\ensuremath{\phi})={6.9}_{\ensuremath{-}2.0\ensuremath{-}1.6}^{+1.9+1.8}\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$, is larger than the previous theoretical estimates but in comparison with the data from Particle Data Group at the level of 1 standard deviation. We also explore some pertinent decay asymmetry parameters that characterize the angular decay distributions. The inclusion of the $W$ exchange contribution provides the nonzero weak phase difference, consequently, allowing us to estimate the direct $CP$ violation and true triple product asymmetries in the concerned process. The numerical results demonstrate that the direct $CP$ violation is at the level of a few percent, and the true triple product asymmetries are also predicted to be tiny, of order ${10}^{\ensuremath{-}2}--{10}^{\ensuremath{-}4}$. The observed small $CP$-violating observables have shown no significant deviations from zero. Our predictions will be subject to stringent tests with precise data from LHCb in the future.

A neural network emulator for the Lyman-α forest 1D flux power spectrum

ABSTRACT The Lyman-α forest offers a unique avenue for studying the distribution of matter in the high redshift universe and extracting precise constraints on the nature of dark matter, neutrino masses, and other ΛCDM extensions. However, interpreting this observable requires accurate modelling of the thermal and ionization state of the intergalactic medium, and therefore resorting to computationally expensive hydrodynamical simulations. In this work, we build a neural network that serves as a surrogate model for rapid predictions of the one-dimensional Lyman-α flux power spectrum (P1D), thereby making Bayesian inference feasible for this observable. Our emulation technique is based on modelling P1D as a function of the slope and amplitude of the linear matter power spectrum rather than as a function of cosmological parameters. We show that our emulator achieves sub-percent precision across the full range of scales (k∥ = 0.1 – $4\, \mathrm{Mpc}^{-1}$) and redshifts (z = 2 – 4.5) considered, and also for three ΛCDM extensions not included in the training set: massive neutrinos, running of the spectral index, and curvature. Furthermore, we show that it performs at the 1 per cent level for ionization and thermal histories not present in the training set and performs at the percent level when emulating down to $k_{\parallel }=8\, \mathrm{Mpc}^{-1}$. These results affirm the efficacy of our emulation strategy in providing accurate predictions even for cosmologies and reionization histories that were not explicitly incorporated during the training phase, and we expect it to play a critical role in the cosmological analysis of the DESI survey.

Effect of Effective Reading on Students’ Academic Performance in Tertiary Institution: A Case Study of Computer Science Department Federal Polytechnic, Ekowe Bayelsa State, Nigeria

Academic performance is the measurement of students’ achievement across various academic subjects. Teachers and perhaps educationists measure academic achievements using classroom performance, graduation grades and results from standardized tests. In this paper, we carried out some statistical analysis to determine if the Grade Point Average (GPA) of students’ academic performance in Computer Science department 2020/2021 National Diploma (ND) one academic session, do depend on the number of hours students spend over the weekends reading their books using simple linear regression analysis and correlation analysis at 5 percent level of significance. The findings of the study shows that there is a linear relationship between the two variables y(GPA) and the number of x(hours) the students spent reading for their examinations, and it also indicates a strong significant difference on the effect of effective reading of students’ academic performance in tertiary institutions.

Simulating large-size quantum spin chains on cloud-based superconducting quantum computers

Quantum computers have the potential to efficiently simulate large-scale quantum systems for which classical approaches are bound to fail. Even though several existing quantum devices now feature total qubit numbers of more than 100, their applicability remains plagued by the presence of noise and errors. Thus, the degree to which large quantum systems can successfully be simulated on these devices remains unclear. Here, we report on numerical results of physics-motivated variational ansatzes, as well as cloud simulations performed on several of IBM's superconducting quantum computers to simulate ground states of spin chains having a wide range of system sizes up to 102 qubits. Our numerical analysis shows that the accuracy of the ground-state energy and fidelity improves substantially by increasing the number of layers used in the ansatzes. From the cloud experiments, we find that the ground-state energies extracted from realizations across different quantum computers and system sizes reach the expected values to within errors that are small (i.e., on the percent level), including the inference of the energy density in the thermodynamic limit from these values. We achieve this accuracy through a combination of physics-motivated variational ansatzes, and efficient, scalable energy-measurement and error-mitigation protocols, including the use of a reference state in the zero-noise extrapolation. By using a 102-qubit system, we have been able to successfully apply up to 3186 CNOT gates in a single circuit when performing gate-error mitigation. Our accurate, error-mitigated results for random parameters in the ansatz states suggest that a standalone hybrid quantum-classical variational approach for large-scale $XXZ$ models considered in this work is feasible.

The Effect of Corporate Social Responsibility Disclosure Index on Firm Performance of Selected Sectoral Industries in Nigeria

Corporate Social Responsibility (CSR) initiatives are charitable events and methods for improving a company's image, satisfying key stakeholders, and increasing financial performance. The issue of CSR initiatives on capital growth and sustainability remains imperative for this study. Therefore, this study is set out to examine the effect of corporate social responsibility disclosure index on firm performance of selected sectoral industries in Nigeria and to investigate the effect of corporate social responsibility on market value of selected sectoral industries in Nigeria. This study adopts multi-stage sampling approaches. A quantitative method was used in which a deductive technique was adopted because the research was based on existing theories and findings from previous investigations. Descriptive statistics, correlation regression panel and cross sectional analysis were adopted for the purpose of this study. The result showed that CSR as a variable has the highest mean = 69.7608) with a standard deviation = 11.7713 indicates that CSR is the most sensitivity variable, while leverage (LEV) has the second highest mean = 55.0760 with a standard deviation = 182.3009 and SIZE has mean = 16.9473 with a standard deviation = 1.0996 indicates that the value of corporate SIZE is also a huge factor to the study. However, the correlations statistics shows that return on asset (ROE) has a positive correction = 0.4468 with return on equity (ROA) at 5 percent level of significant. TobinQ has a positive relationship with ROA = 0.5321 and ROE = 0.0842 at 5 percent level of significant respectively. CSR has a negative relationship with ROA = −0.0948*, ROE = −0.0760 and Tobin Q = −0.0734 at 5 percent level of significant respectively. SIZE has a positive significant relationship with ROA = 0.0589, ROE = 0.0826 and CSR = 0.2449. The findings revealed that firms in Nigeria are yet to significantly use CSR to promote their performances like what is done by firms in developed economies. Therefore, as part of the recommendation from this study, Nigerian firms are advised to pay more attention to being CSR responsible and find ways by which this can translate to improved profit and enhancement of their overall performances.

Transverse momentum resummation at N3LL+NNLO for diboson processes

Diboson processes are one of the most accessible and stringent probes of the electroweak gauge structure of the Standard Model at the LHC. They will be probed at the percent level at the high-luminosity LHC, challenging current theory predictions. We present transverse momentum resummed calculations at N3LL+NNLO for the processes ZZ, WZ, WH and ZH, compare our predictions with most recent LHC data and present predictions at 13.6 TeV including theory uncertainty estimates. For W+W− production we further present jet-veto resummed results at N3LLp+NNLO. Our calculations will be made publicly available in the upcoming MCFM release and allow future analyses to take advantage of improved predictions.

Does Foreign Exchange Rate Moderate the Relationship Between Foreign Capital Outflows and Economic Growth? A Panel Data Investigation of Kenya’s Economy (1986-2021)

Purpose – This study aims to evaluate the nexus between foreign exchange rate, foreign capital outflow and economic growth in Kenya. This study focused on analyzing the moderating role of foreign exchange rate on the relationship between foreign capital outflow and economic growth in Kenya. The foreign exchange rate is an important measure in the economic development. Its fluctuations affect the levels of foreign capital outflow. The loss of foreign exchange reserve due to foreign capital outflow translates to great amount of savings lost in the country.
 Design/methodology/approach – This study employed a Panel Data approach and the World Bank’s residual model in the estimation of the magnitude of foreign capital outflow from Kenya during the period between 1986 to 2021.
 Findings – The panel data results revealed that the interaction variable MOD_FER had a coefficient of 0.05 and a significant probability value of 0.0001 which is significant at 5 percent level of significance. This means that foreign exchange rate moderated the relationship between foreign capital outflow and economic growth in Kenya during the period of this study. When the relationship with foreign capital outflow was moderated by 0.05 units then GDP grew by 1 unit. As such, foreign exchange rate is a significant factor in the relationship between foreign capital outflow and economic growth in Kenya.
 Originality/value – This study calculates the magnitude effect of foreign exchange rate in the relationship between foreign capital outflow and economic growth in Kenya for the first time. In addition, the study calculates the magnitude change of foreign capital outflow for MNE’s due to foreign exchange rate oscillations. This study suggests many policy proposals to deal with the challenge of foreign exchange rate, foreign capital outflow and economic growth in Kenya. The results of this study will benefit policy makers by providing them with data-based evidence that will guide them in making appropriate policies that discourage foreign capital outflow and institute proper management of foreign exchange rate to boost economic growth in Kenya.

Outward Foreign Direct Investments and Economic Growth: An Investigation of Kenya

Purpose – The purpose of this study was to evaluate the effect of outward foreign direct investments on economic growth in Kenya.
 Design/methodology/approach – The study applied the panel data model to analyze the data collected. Unit root tests were also conducted on the variables to avoid the problem of having a spurious regression or white noise in the model. The Levin, Lin and Chu T- statistic test for stationarity which is suitable for panel data sets was used for this study. A Hausman test was conducted to determine whether to use the fixed effects model or the random effects model to address the objectives of the study.
 Findings – OFDI had a coefficient of 0.06 and a probability value of 0.0011 which is significant at 5 percent level of significance. This means that when OFDI grew by 0.06 units then GDP grew by 1 unit during the period of study. 
 Practical implications – As such there is a positive and significant relationship between Outward FDI and economic growth to a magnitude that a o.06% increase in outward FDI will translate to a 1% increased economic growth. As such, outward FDI is beneficial to Kenya’s economic growth.
 Originality/value – This study advances OFDI theory and contributes to the growing discussion on the effect it has on the developing country’s economy. The study also offers practical contributions on how the government can take a deliberate effort to spur economic growth by regulating the level of outward FDI as this determines the effectiveness of policymaking and fosters international mutual understanding, cultural exchange and firm growth and innovation. Ultimately, this contributes to a healthy economy.

An analytic approach to quasinormal modes for coupled linear systems

Quasinormal modes describe the ringdown of compact objects deformed by small perturbations. In generic theories of gravity that extend General Relativity, the linearized dynamics of these perturbations is described by a system of coupled linear differential equations of second order. We first show, under general assumptions, that such a system can be brought to a Schrödinger-like form. We then devise an analytic approximation scheme to compute the spectrum of quasinormal modes. We validate our approach using a toy model with a controllable mixing parameter ε and showing that the analytic approximation for the fundamental mode agrees with the numerical computation when the approximation is justified. The accuracy of the analytic approximation is at the (sub-) percent level for the real part and at the level of a few percent for the imaginary part, even when ε is of order one. Our approximation scheme can be seen as an extension of the approach of Schutz and Will [1] to the case of coupled systems of equations, although our approach is not phrased in terms of a WKB analysis, and offers a new viewpoint even in the case of a single equation.

Model independent bounds on type Ia supernova absolute peak magnitude

We put constraints on the peak absolute magnitude, $M_B$ of type Ia supernova using the Pantheon sample for type Ia supernova observations and the cosmic chronometers data for the Hubble parameter by a model independent and non-parametric approach. Our analysis is based on the Gaussian process regression. We find percent level bounds on the peak absolute magnitude given as $M_B=-19.384\pm0.052$. For completeness and to check the consistency of the results, we also include the Baryon acoustic oscillation data and the prior of the comoving sound horizon from Planck 2018 cosmic microwave background observations. The inclusion of these two data gives tighter constraints on $M_B$ at the sub-percent level. We obtain constraints on $M_B$ from the combination of pantheon compilation of type Ia supernova observations and baryon acoustic oscillation observations given as $M_B=-19.396\pm0.016$. When adding the cosmic chronometer observations with these observations, we find $M_B=-19.395\pm0.015$. The mean values of peak absolute magnitude from all these data are consistent with each other and the values are approximately equal to $-19.4$.

Twist-four gravitational form factor at NNLO QCD from trace anomaly constraints

It is known that the trace anomaly in the QCD energy-momentum tensor Tμν can be attributed to the anomalies for each of the gauge-invariant quark part and gluon part of Tμν, and their explicit three-loop formulas have been derived in the overline{textrm{MS}} scheme in the dimensional regularization. The matrix elements of this quark/gluon decomposition of the QCD trace anomaly allow us to derive the QCD constraints on the hadron’s gravitational form factors, in particular, on the twist-four gravitational form factor, {overline{C}}_{q,g} . Using the three-loop quark/gluon trace anomaly formulas, we calculate the forward (zero momentum transfer) value of the twist-four gravitational form factor {overline{C}}_{q,g} at the next-to-next-to-leading-order (NNLO) accuracy. We present quantitative results for nucleon as well as for pion, leading to a model-independent determination of the forward value of {overline{C}}_{q,g} . We find quite different pattern in the obtained results between the nucleon and the pion. In particular, for the nucleon, the present information from experiment and lattice QCD on the nonperturbative matrix elements arising in our NNLO formula allows us to obtain a prediction of the forward value of {overline{C}}_{q,g} at the accuracy of a few percent level.