arXiv subjects

Waqas Ahmed

Publications and source records attributed to Waqas Ahmed.

At least 55 records · Page 3Linked to original sources

arXiv2023

A note on supergravity inflation in braneworld

We discuss supergravity inflation in braneworld cosmology for the class of potentials $V(ϕ)=αϕ^n\rm{exp}(-β^m ϕ^m)$ with $m=1,~2$. These minimal SUGRA models evade the $η$ problem due to a broken shift symmetry and can easily accommodate the observational constraints. In the high energy regime $V/λ\gg 1$, the numerical predictions and approximate analytic formulas are given for the scalar spectral index $n_s$ and tensor-to-scalar ratio $r$. The models with smaller $n$ are preferred while the models with larger $n$ are out of the $2σ$ region. Remarkably, the $ρ^2/λ$ correction to the energy density in Friedmann equation results in sub-Planckian inflaton excursions $Δϕ<1$.

hep-th↗

arXiv2023

Observable r, Gravitino Dark Matter, and Non-thermal Leptogenesis in No-Scale Supergravity

We analyse the shifted hybrid inflation in a no-scale SU(5) model with supersymmetry, which naturally circumvents the monopole problem. The no-scale framework is derivable as the effective field theory of the supersymmetric (SUSY) compactifications of string theory, and it yields a flat potential with no anti-de Sitter vacua, resolving the $η$ problem. The model predicts a scalar spectral tilt $n_s$ compatible with the most recent measurements by the Planck satellite, while also accommodating observable values of the tensor-to-scalar ratio $r$ ($\sim 0.0015$), potentially measurable by the near-future experiments. Moreover, the proton decay lifetime in the presence of the dimension-5 operators is found to lie above the current limit imposed by the Super-Kamiokande experiment. A realistic scenario of reheating and non-thermal leptogenesis is invoked, wherein the reheating temperature $T_r$ lies in the $\{2 \times 10^6 \lesssim T_r \lesssim 2 \times 10^9\}$ GeV range, and at the same time the gravitino makes a viable dark matter (DM) candidate.

hep-ph↗

arXiv2023

Investigating the GmSUGRA in the MSSM through the long-lived bino NLSP at the HL-LHC

The axino, the supersymmetric partner of axion, is a well-motivated warm/hot dark matter candidate, and provides a natural solution to the relic density problem for the bino-like neutralino if it is the lightest supersymmetric particle (LSP). With the Generalized Minimal Supergravity, we study such kind of the viable parameter space where the bino-like neutralino is the next-to-LSP (NLSP) and the axino is the LSP. In addition, we consider a scenario where the bino is a long-lived NLSP with the lifetime varying from $10^{-6}$s to $10^{-4}$s, and then propose a new signal searching scheme involving one displaced photon together with the large missing transverse momentum at the HL-LHC. The bino-like lightest neutralino lies under or around 100 GeV and is produced as a decay product of the right-handed sleptons.The relevant axion coupling $f_a$ can be probed up to $\mathcal{O}(10^9)$ GeV at 2$σ$ level for the right-handed slepton mass under 300 GeV and the lightest neutralino mass under 100 GeV.

hep-ph↗

arXiv2023

LHC Run-3, $b-τ$ Yukawa Unification and Dark Matter Implications in SUSY 4-2-2 model

We revisit the bottom and $τ$ Yukawa coupling unification in supersymmetric $4$-$2$-$2$ model and present for the first time the sbottom-neutralino co-annihilation scenario consistent with the bottom and $τ$ Yukawa coupling unification. In addition, we show gluino-neutralino, stop-neutralino, stau-neutralino, chargino-neutralino, and A-resonance scenario and show that all such solutions are consistent with existing experimental collider constraints, Planck2018 dark matter relic density bounds as well as direct and indirect bounds on neutralino-nucleons scattering cross sections. We show that in sbottom-neutralino co-annihilation scenario, the sbottom mass is about 2 TeV whereas in the case of gluino-neutralino, stop-neutralino, the gluino mass can be between 1 TeV to 3 TeV and stop mass in the range of 1 TeV to 3.5 TeV. {Moreover, in the case of co-annihilation scenario, the stau and chargino masses can be as heavy as 3.5 TeV,} while the A-resonance solutions are in the range of 0.5 TeV to 3.5 TeV. We anticipate that some part of the parameter space will be accessible in the supersymmetry searches at LHC Run-3 and beyond.

hep-ph↗

arXiv2022

Radiative Symmetry breaking, Cosmic Strings and Observable Gravity Waves in $U(1)_R$ symmetric $SU(5) \times U(1)_χ$

We implement shifted hybrid inflation in the framework of supersymmetric $SU(5) \times U(1)_χ$ GUT model which provides a natural solution to the monopole problem appearing in the spontaneous symmetry breaking of $SU(5)$. The $U(1)_χ$ symmetry is radiatevely broken after the end of inflation at an intermediate scale, yielding topologically stable cosmic strings. The Planck's bound on the gravitational interaction strength of these strings, characterized by $G_N μ_s$ are easily satisfied with the $U(1)_χ$ symmetry breaking scale which depends on the initial boundary conditions at the GUT scale. The dimension-5 proton lifetime for the decay $p \rightarrow K^+ \barν$, mediated by color-triplet Higgsinos is found to satisfy current Super-Kamiokande bounds for SUSY breaking scale $M_{\text{SUSY}} \gtrsim 12.5$ TeV. We show that with minimal Kähler potential, the soft supersymmetry breaking terms play a vital role in bringing the scalar spectral index $n_s$ within the Planck's latest bounds, although with small tensor modes $r \lesssim 2.5 \times 10^{-6}$ and $SU(5)$ gauge symmetry breaking scale in the range ($2 \times 10^{15} \lesssim M_α \lesssim 2 \times 10^{16}$) GeV. By employing non-minimal terms in the Kähler potential, the tensor-to-scalar ratio approaches observable values ($r \lesssim 10^{-3}$) with the $SU(5)$ symmetry breaking scale $M_α \simeq 2 \times 10^{16}$ GeV.

hep-ph↗

arXiv2022

Primordial Black Holes and Gravitational Waves in Hybrid Inflation with Chaotic Potentials

We study the formation of primordial black hole (PBH) dark matter and the generation of scalar induced secondary gravitational waves (SIGWs) in a non-supersymmetric model of hybrid inflation with chaotic (polynomial-like) potential, including one-loop radiative corrections. A radiatively corrected version of these models is entirely consistent with Planck's data. By adding non-canonical kinetic energy term in the lagrangian, the inflaton experiences a period of ultra-slow-roll, and the amplitude of primordial power spectrum is enhanced to $O(10^{-2})$. The enhanced power spectra of primordial curvature perturbations can have both sharp and broad peaks. %In the enhancement mechanism we explore two possible extensions by employing a Guassian and a step size kinetic function. A wide mass range of PBHs is realized in our model with the frequencies of scalar induced gravitational waves ranged from nHz to kHz. We present several benchmark points where the PBH mass generated during inflation is around $(1 - 100) \, M_{\odot}$, $(10^{-9} - 10^{-7}) \, M_{\odot}$ and $(10^{-16} - 10^{-11}) \, M_{\odot}$. The PBHs can make up most of the dark matter with masses around $(10^{-16} - 10^{-11}) \, M_{\odot}$ and $(1 - 100) \, M_{\odot}$, and their associated SIGWs can be probed by the upcoming ground and space-based gravitational wave (GW) observatories. The evidence of stochastic process recently reported by NANOGrav may be interpreted as SIGWs associated with the formation of PBHs. These SIGWs may also be tested by future interferometer-type GW observations of SKA, DECIGO, LISA, BBO, TaiJi, TianQin, CE and ET.

astro-ph.CO↗

arXiv2022

Web 3.0 Adoption Behavior: PLS-SEM and Sentiment Analysis

Web 3.0 is considered as future of Internet where decentralization, user personalization and privacy protection would be the main aspects of Internet. Aim of this research work is to elucidate the adoption behavior of Web 3.0through a multi-analytical approach based on Partial Least Squares Structural Equation Modelling (PLS-SEM) and Twitter sentiment analysis. A theoretical framework centered on Performance Expectancy (PE), Electronic Word-of-Mouth (eWOM) and Digital Dexterity (DD), was hypothesized towards Behavioral Intention (INT) of the Web 3.0 adoption. Surveyed data were collected through online questionnaires and 167 responses were analyzed through PLS-SEM. While 3,989 tweets of Web3 were analyzed by VADER sentiment analysis tool in RapidMiner. PLS-SEM results showed that DD and eWOM had significant impact while PE had no effect on INT. Moreover, these results were also validated by PLS-Predict method. While sentiment analysis explored that 56% tweets on Web 3.0 were positive in sense and 7% depicted negative sentiment while remaining were neutral. Such inferences are novel in nature and an innovative addition to web informatics and could support the stakeholders towards web technology integration

cs.CY↗

arXiv2022

Probing the Supersymmetric Grand Unified Theories with Gravity Mediation at the Future Proton-Proton Colliders and Hyper-Kamiokande Experiment

With the grand desert hypothesis, we have proposed to probe the supersymmetric Grand Unified Theories (GUTs) at the future proton-proton (pp) colliders and Hyper-Kamiokande experiment previously. In this paper, we study the supersymmetric GUTs with gravity mediated supersymmetry breaking in details. First, considering the dimension-six proton decay via heavy gauge boson exchange, we point out that we can probe the supersymmetric GUTs with GUT scale $M_{GUT}$ up to $1.778\times 10^{16}$ GeV at the Hyper-Kamiokande experiment. Second, for the supersymmetric GUTs with $M_{GUT} \ge 1.0\times 10^{16}$ GeV and $M_{GUT} \ge 1.2\times 10^{16}$ GeV, we show that the upper bounds on the universal gaugino mass are $7.2$ TeV and 3.5 TeV, respectively, and thus the corresponding upper bounds on gluino mass are 15 TeV and 8 TeV, respectively. Also, we shall study the masses for charginos, neutralinos, squarks, sleptons, and Higgs particles in details. In particular, the supersymmetric GUTs with $M_{GUT} \leq 1.2\times 10^{16}$ GeV can be probed at the Hyper-Kamiokande experiment, and the supersymmetric GUTs with $M_{GUT}\ge 1.2\times 10^{16}$ GeV can be probed at the future 100 TeV pp collider experiments such as the ${\rm FCC}_{\rm hh}$ and SppC via gluino searches. Thus, the supersymmetric GUTs with gravity mediation can be probed by the ${\rm FCC}_{\rm hh}$, SppC, and Hyper-Kamiokande experiments. In our previous study, we have shown that the supersymmetric GUTs with anomaly and gauge mediated supersymmetry breakings are well within the reaches of these experiments. Therefore, our proposal provides the concrete scientific goal for the ${\rm FCC}_{\rm hh}$, SppC, and Hyper-Kamiokande experiments: probing the supersymmetric GUTs.

hep-ph↗

arXiv2022

Smooth Hybrid Inflation with Low Reheat Temperature and Observable Gravity Waves in $SU(5) \times U(1)_χ$ Super-GUT

We realize smooth hybrid inflation in the framework of supersymmetric $SU(5) \times U(1)_χ\subset SO(10)$ model which provides a natural solution to the monopole problem appearing in the spontaneous symmetry breaking of $SU(5)$. The breaking of $U(1)_χ$ symmetry leaves a residual discrete $Z_2$ symmetry, that serves as the MSSM matter parity, realizing the possibility of the lightest supersymmetric particle as a cold dark matter candidate. The $d = 5$ proton lifetime for the decay $p \rightarrow K^+ \barν$, mediated by color-triplet Higgsinos is found to satisfy current experimental bounds if split-high scale SUSY scenario is employed. We show that with minimal Kähler potential, the soft supersymmetry breaking terms play a vital rôle in bringing the scalar spectral index $n_s$ within the Planck's latest bounds. In a minimal Kähler potential setup, small values of tensor-to-scalar ratio $r \lesssim 3.5 \times 10^{-7}$ are obtained, whereas the gravitino mass turns out to be in the range that favors PeV scale SUSY but is not sufficiently high to avoid the $d = 5$ proton decay. A non-minimal Kähler potential including higher-order corrections is required to realize successful inflation with central value of scalar spectral index $n_s = 0.9655$, large tensor modes $r \lesssim 0.056$ and a low reheat temperature $(3\times 10^{6} \lesssim T_r \lesssim 6.5 \times 10^7 )$ GeV consistent with leptogenesis and baryogenesis.

hep-ph↗

arXiv2022

Constraining the Cosmic Strings Gravitational Wave Spectra in No Scale Inflation with Viable Gravitino Dark matter and Non Thermal Leptogenesis

We revisit the hybrid inflation model gauged by $U(1)_{B-L}$ extension of the Minimal Supersymmetric Standard Model (MSSM) in a no-scale background. Considering a single predictive framework, we study inflation, leptogenesis, gavitino cosmology, and the stochastic background of gravitational waves produced by metastable cosmic strings. The spontaneous breaking of $U(1)_{B-L}$ at the end of inflation produces a network of metastable cosmic strings while, the interaction between $U(1)_{B-L}$ Higgs field and the neutrinos generate heavy Majorana masses for the right-handed neutrinos. The heavy Majorana masses explain the tiny neutrino masses via the seesaw mechanism, a realistic scenario for reheating and non-thermal leptogenesis. We show that a successful non-thermal leptogenesis and a stable gravitino as a dark matter candidate can be achieved for a wide range of reheating temperatures and $U(1)_{B-L}$ symmetry breaking scales. The possibility of realizing metastable cosmic strings in a grand unified theory (GUT) setup is briefly discussed. We find that a successful reheating with non-thermal leptogenesis and gravitino dark matter restrict the allowed values of string tension to a narrow range $10^{-9} \lesssim Gμ_{CS} \lesssim 8 \times 10^{-6}$, predicting a stochastic gravitational-wave background that lies within the 1-$σ$ bounds of the recent NANOGrav 12.5-yr data, as well as within the sensitivity bounds of future GW experiments.

hep-ph↗

arXiv2022

Dark Matter in the CP-violating NMSSM

In the Next-to-Minimal Supersymmetric Standard Model there is a strong correlation between the mass terms corresponding to the singlet Higgs and the singlino interaction states, both of which are proportional to the parameter $κ$. If this parameter is complex, explicit CP-violation occurs in the Higgs as well as the neutralino sectors of the model at the tree level, unlike in the minimal scenario. A small magnitude of $κ$ typically yields a $\cal{O}$(10) GeV lightest neutralino with a dominant singlino component. In such a scenario, the phase of $κ$, beside modifying the properties of the five Higgs bosons, can also have a crucial impact on the phenomenology of the neutralino dark matter. In this study we perform a first investigation of this impact on the relic abundance of the dark matter solutions with sub-100 GeV masses, obtained for parameter space configurations of the model that are consistent with a variety of current experimental data.

hep-ph↗

arXiv2022

$μ$-hybrid Inflation, Gravitino Dark Matter and Stochastic Gravitational Wave Background from Cosmic Strings

We present a successful realization of supersymmetric $μ$-hybrid inflation model based on a gauged $U(1)_{B-L}$ extension of the minimal supersymmetric standard model, with the soft supersymmetry breaking terms are playing an important role. Successful non-thermal leptogenesis with gravitino dark matter yields a reheat temperature in the range $2 \times 10^{7} \lesssim T_R \lesssim 5 \times 10^{9}$ GeV. This corresponds to the predictions $2 \times 10^{-18} \lesssim r\lesssim 4 \times 10^{-13}$ for the tensor to scalar ratio, and $-2 \times 10^{-6} \lesssim dn_s/d\ln k \lesssim -5 \times 10^{-11}$ for the running of the scalar spectral index. The $B-L$ breaking scale is estimated as $ 6 \times 10^{14}\lesssim M/ \text{GeV}\lesssim 10^{16}$, calculated at the central value of the scalar spectral index, $n_s =0.9655$, reported by Planck 2018. Finally, in a grand unified theory setup the dimensionless string tension parameter associated with the metastable strings is in the range $ 10^{-9} \lesssim Gμ_\text{cs} \lesssim 10^{-6}$ corresponding to a stochastic gravitational wave background lying within the 2$σ$ bound of the recent NANOGrav 12.5-yr data.

hep-ph↗

arXiv2022

Probing Relatively Heavier Right-Handed Selectron at the CEPC, $\rm\bf {FCC_{ee}}$ and ILC

We employ the low energy Minimal Supersymmetric Standard Model (MSSM) to explore the parameter space associated with $Z$-pole and Higgs-pole solutions. Such parameter spaces can not only saturate the cold dark matter relic density bound within 5$σ$ set by the Planck 2018, but also satisfy the other standard collider mass bounds and B-physics bounds. In particular, we show that the right-handed selectron can be light. Thus, we propose a search for the relatively heavier right-handed selectron at the future lepton colliders with the center-of-mass energy $\sqrt{s}=240$ GeV and integrated luminosity 3000 $\rm{fb^{-1}}$ via mono-photon channel: $e^{+}_{R} e^{-}_{R}\rightarrow {\tilde χ_{1}^{0}(bino)}+{\tilde χ_{1}^{0}(bino)}+γ$. We show that for the $Z$-pole case the right-handed selectron will be excluded up to 180 GeV and 210 GeV respectively at 3$σ$ and 2$σ$, while the right-handed selectron will be excluded up to 140 GeV and 180 GeV respectively at 3$σ$ and 2$σ$ in case of Higgs-pole.

hep-ph↗

arXiv2021

Human Activity Recognition using Attribute-Based Neural Networks and Context Information

We consider human activity recognition (HAR) from wearable sensor data in manual-work processes, like warehouse order-picking. Such structured domains can often be partitioned into distinct process steps, e.g., packaging or transporting. Each process step can have a different prior distribution over activity classes, e.g., standing or walking, and different system dynamics. Here, we show how such context information can be integrated systematically into a deep neural network-based HAR system. Specifically, we propose a hybrid architecture that combines a deep neural network-that estimates high-level movement descriptors, attributes, from the raw-sensor data-and a shallow classifier, which predicts activity classes from the estimated attributes and (optional) context information, like the currently executed process step. We empirically show that our proposed architecture increases HAR performance, compared to state-of-the-art methods. Additionally, we show that HAR performance can be further increased when information about process steps is incorporated, even when that information is only partially correct.

eess.SP↗

arXiv2021

Gravitino Dark matter, Non Thermal Leptogenesis and Low reheating temperature in No-scale Higgs Inflation

We revisit Higgs inflation in the framework of a minimal extension of the Standard Model gauge symmetry by a $U(1)_{B-L}$ factor. Various aspects are taken into account with particular focus on the role of the supersymmetry breaking (SUSY) scale and the cosmological constraints associated with the gravitino. The scalar potential of the model is considered in the context of no-scale supergravity consisting of the F-part constructed from the Kähler function, the D-terms and soft SUSY contributions. We investigate several limiting cases and by varying the SUSY scale from a few TeV up to intermediate energies, for a spectral index around $n_s\sim 0.9655$ and reheating temperature $T_r\le 10^{9}$ GeV we find that the value of the tensor-to-scalar ratio ranges from $r\approx 10^{-3}$ to $10^{-2}$. Furthermore, it is shown that for certain regions of the parameter space the gravitino can live sufficiently long and as such is a potential candidate for a dark matter component. In general, the inflationary scenario is naturally implemented and it is consistent with non-thermal leptogenesis whereas the dominant decay channel of the inflaton yields right-handed neutrinos. Other aspects of cosmology and particle physics phenomenology are briefly discussed. Finally, we investigate the case where the inflaton is initially relaxed in a false minimum and estimate its probability to decay to the true vacuum.

hep-ph↗

arXiv2021

Security in Next Generation Mobile Payment Systems: A Comprehensive Survey

Cash payment is still king in several markets, accounting for more than 90\ of the payments in almost all the developing countries. The usage of mobile phones is pretty ordinary in this present era. Mobile phones have become an inseparable friend for many users, serving much more than just communication tools. Every subsequent person is heavily relying on them due to multifaceted usage and affordability. Every person wants to manage his/her daily transactions and related issues by using his/her mobile phone. With the rise and advancements of mobile-specific security, threats are evolving as well. In this paper, we provide a survey of various security models for mobile phones. We explore multiple proposed models of the mobile payment system (MPS), their technologies and comparisons, payment methods, different security mechanisms involved in MPS, and provide analysis of the encryption technologies, authentication methods, and firewall in MPS. We also present current challenges and future directions of mobile phone security.

cs.CR↗

arXiv2021

Finding the Contextual Gap Towards Employee Engagement in Financial Sector: A Review Study

This review paper identifies the core evidence of research on employee engagement , considering a stern challenge facing the financial sector nowadays. The study highlights the noteworthy knowledge gaps that will support human resource management practitioners to embed in the research towards sectoral context. Pertinent articles were selected through key search points and excerpt-related literature. The key search points covered the topic related to different terms of engagement for example "employee engagement" OR "work engagement" OR "job engagement" OR "organization engagement" OR "staff engagement" OR "personnel engagement" which were steered in diverse context particularly financial sector. Through critically reviewing the literature for the last 11 years i.e., 2009-2019, we discovered 91 empirical studies in financial sector. From these studies, we found the overall concept of engagement and its different determinants (e.g., organizational factors, individual factors, job factors) as well as its various outcomes (e.g., employee outcomes, organizational outcomes). We also formulated a conceptual model to expand the body of knowledge in the area of employee engagement for a better understanding of its predictors and outcomes. Besides, limitations of the study and future recommendations are also contemplated.

econ.GN↗

arXiv2021

User Behavior Assessment Towards Biometric Facial Recognition System: A SEM-Neural Network Approach

A smart home is grounded on the sensors that endure automation, safety, and structural integration. The security mechanism in digital setup possesses vibrant prominence and the biometric facial recognition system is novel addition to accrue the smart home features. Understanding the implementation of such technology is the outcome of user behavior modeling. However, there is the paucity of empirical research that explains the role of cognitive, functional, and social aspects of end-users acceptance behavior towards biometric facial recognition systems at homes. Therefore, a causal research survey was conducted to comprehend the behavioral intention towards the use of a biometric facial recognition system. Technology Acceptance Model (TAM)was implied with Perceived System Quality (PSQ) and Social Influence (SI)to hypothesize the conceptual framework. Data was collected from 475respondents through online questionnaires. Structural Equation Modeling(SEM) and Artificial Neural Network (ANN) were employed to analyze the surveyed data. The results showed that all the variables of the proposed framework significantly affected the behavioral intention to use the system. The PSQ appeared as the noteworthy predictor towards biometric facial recognition system usability through regression and sensitivity analyses. A multi-analytical approach towards understanding the technology user behavior will support the efficient decision-making process in Human-centric computing.

cs.HC↗