arXiv subjects

M. Adeel Ajaib

Publications and source records attributed to M. Adeel Ajaib.

18 recordsLinked to original sources

arXiv2026

Neutralino Dark Matter in SU(5) after H.E.S.S. and Direct-Detection Searches

We examine the impact of gamma-ray line and direct-detection searches on neutralino dark matter in supersymmetric SU(5) with non-universal gaugino masses. Under the assumption that neutralinos constitute all halo dark matter, a nearly pure wino benchmark at 1 TeV is essentially excluded by the H.E.S.S. line limits for both cusped and cored density profiles. Higgsino and wino-Higgsino benchmarks are independently excluded by direct detection. In contrast, a bino benchmark near thermal saturation combines suppressed present-day line emission with scattering below the displayed experimental limits. Mixed bino-wino solutions illustrate the complementarity of the two searches and the dependence of the line interpretation on the Galactic halo profile. We relate these results to the GUT-scale gaugino hierarchy and the SU(5) scalar and Higgs boundary conditions. Thermally underabundant solutions require additional production to realize the full-density assumption. Comparing the calculated signals with published electroweakino predictions, we identify the spectrum-dependent corrections and collider tests needed to determine the surviving parameter space.

hep-ph↗

arXiv2025

Emergent Grand Unified Structure in a 4 x 4 Nilpotent Matrix Algebra

We show that nilpotent matrices that yield the Schrodinger equation from its first order form encode the fingerprints of grand unified theories. We perform a rigorous search for all such nilpotent matrices and find that the resulting matrices naturally organize into suggestive group theoretic structures without any other a priori assumptions. The antisymmetric sector consists of three groups of sixteen matrices, each of which further splits as 16 = 12 + 4 and exhibits unique characteristics in the step potential scattering problem. The symmetric zero-diagonal sector also forms three families, mirroring the quark-lepton decomposition of the Pati-Salam model. These results may help answer why there are three families of fermions and also demonstrate that the 4 x 4 matrix algebra is a compact, nontrivial shadow of the SO(10) embedding, with fermion-like and gauge-like subspaces.

hep-ph↗

arXiv2025

Explainable AI for Curie Temperature Prediction in Magnetic Materials

We explore machine learning techniques for predicting Curie temperatures of magnetic materials using the NEMAD database. By augmenting the dataset with composition-based and domain-aware descriptors, we evaluate the performance of several machine learning models. We find that the Extra Trees Regressor delivers the best performance reaching an R^2 score of up to 0.85 $\pm$ 0.01 (cross-validated) for a balanced dataset. We employ the k-means clustering algorithm to gain insights into the performance of chemically distinct material groups. Furthermore, we perform the SHAP analysis to identify key physicochemical drivers of Curie behavior, such as average atomic number and magnetic moment. By employing explainable AI techniques, this analysis offers insights into the model's predictive behavior, thereby advancing scientific interpretability.

cond-mat.mtrl-sci↗

arXiv2023

Muon g-2 and Dark Matter in the NUGM + NUHM2 model

We analyze the NUGM + NUHM2 model and study the implications of recent experimental constraints on the parameter space of this model. We also explore the nature of dark matter in this model and present the parameter space characterized by various compositions of the neutralino. The region of the parameter space that satisfies the observed deviation in the anomalous magnetic moment of the muon is explored more rigorously. We also present results corresponding to the production cross section and decay widths of a light CP-even Higgs boson and observe that there is a narrow region of the parameter space corresponding to a light stau which explains the observed deviation in the muon g-2 and also leads to enhancement in the Higgs production and decay widths.

hep-ph↗

arXiv2017

SU(5) with Non-Universal Gaugino Masses

We explore the sparticle spectroscopy of the supersymmetric SU(5) model with non-universal gaugino masses in light of latest experimental searches. We assume that the gaugino mass parameters are independent at the GUT scale. We find that the observed deviation in the anomalous magnetic moment of the muon can be explained in this model. The parameter space that explains this deviation predicts a heavy colored sparticle spectrum whereas the sleptons can be light. We also find a notable region of the parameter space that yields the desired relic abundance for dark matter. In addition, we analyze the model in light of latest limits from direct detection experiments and find that the parameter space corresponding to the observed deviation in the muon anomalous magnetic moment can be probed at some of the future direct detection experiments.

hep-ph↗

arXiv2016

Neutralinos and Sleptons at the LHC in Light of Muon $(g-2)_μ$

We study the muon $(g-2)_μ$ anomaly in light of neutralino dark matter and the LHC. We scan the MSSM parameters relevant to $(g-2)_μ$ and focus on three distinct cases with different neutralino compositions. We find that the 2$σ$ range of $(g-2)_μ$ requires the smuon ($\tildeμ_1$) to be lighter than $\sim$ 500 (1000) GeV for $\tan β=10\,(50)$. Correspondingly the two lightest neutralinos, $\tildeχ_{1}^0, \tildeχ_{2}^0$, have to be lighter than $\sim$ 300 (650) GeV and 900 (1000) GeV respectively. We explore the prospects of searching the light smuon and neutralinos at the LHC, in conjunction with constraints arising from indirect dark matter (DM) detection experiments. The upcoming run of the LHC will be able to set $95\%$ CL exclusion limit on $M_{\tildeχ_{2}^0}$ ($\sim 475 - 1300$ GeV) and $m_{\tilde{l}}$ ($\sim 670-775$ GeV) with $M_{\tildeχ_{1}^0} \sim 100-250$ GeV at 3000 fb$^{-1}$ luminosity in multi-lepton + missing energy channel.

hep-ph↗

arXiv2015

GUT-Inspired Supersymmetric Model for h\rightarrow γγand Muon g-2

We study a GUT-inspired supersymmetric model with non-universal gaugino masses that can explain the observed muon g-2 anomaly while simultaneously accommodating an enhancement or suppression in the h \rightarrowγγdecay channel. In order to accommodate these observations and m_h \simeq 125-126 GeV, the model requires a spectrum consisting of relatively light sleptons whereas the colored sparticles are heavy. The predicted stau mass range corresponding to R_{γγ}\ge 1.1 is 100 {\rm \ GeV} \lesssim m_{\tildeτ} \lesssim 200 {\rm \ GeV}. The constraint on the slepton masses, particularly on the smuons, arising from considerations of muon g-2 is somewhat milder. The slepton masses in this case are predicted to lie in the few hundred GeV range. The colored sparticles turn out to be considerably heavier with m_{\tilde{g}} \gtrsim 4.5 {\rm \ TeV} and m_{\tilde{t}_1} \gtrsim 3.5 {\rm \ TeV}, which makes it challenging for these to be observed at the 14 TeV LHC.

hep-ph↗

arXiv2014

Split Sfermion Families, Yukawa Unification and Muon g-2

We consider two distinct classes of Yukawa unified supersymmetric SO(10) models with non-universal and universal soft supersymmetry breaking (SSB) gaugino masses at M_{\rm GUT}. In both cases, we assume that the third family SSB sfermion masses at M_{\rm GUT} are different from the corresponding sfermion masses of the first two families (which are equal). For the SO(10) model with essentially arbitrary (non-universal) gaugino masses at M_{\rm GUT}, it is shown that t-b-τYukawa coupling unification is compatible, among other things, with the 125 GeV Higgs boson mass, the WMAP relic dark matter density, and with the resolution of the apparent muon g-2 anomaly. The colored sparticles in this case all turn out to be quite heavy, of order 5 TeV or more, but the sleptons (smuon and stau) can be very light, of order 200 GeV or so. For the SO(10) model with universal gaugino masses and NUHM2 boundary conditions, the muon g-2 anomaly cannot be resolved. However, the gluino in this class of models is not too heavy, \lesssim 3 TeV, and therefore may be found at the LHC.

hep-ph↗

arXiv2013

Higgs and Sparticle Masses from Yukawa Unified SO(10): A Snowmass White Paper

We discuss ways to probe t-b-tau Yukawa coupling unification condition at the Energy and Intensity frontiers. We consider non-universal soft supersymmetry breaking mass terms for gauginos related by the SO(10) grand unified theory (GUT). We have previously shown that t-b-tau Yukawa coupling unification prefers a mass of around 125 GeV for the Standard Model-like Higgs boson with all colored sparticle masses above 3 TeV. The well-known MSSM parameter tan(beta) is about 47-48 and neutralino-stau coannihilation yields the desired relic dark matter density.

hep-ph↗

arXiv2013

Sparticle Spectroscopy from SO(10) GUT with a Unified Higgs Sector

We study the low energy implications, especially the particle spectroscopy, of SO(10) grand unification in which the SO(10) symmetry is broken to the Standard Model gauge group with a single pair of (144+\bar144) dimensional Higgs multiplet (unified Higgs sector). In this class of models, the asymptotic relation Y_b \approx Y_τ\approx Y_t/6 among the third generation quark and lepton Yukawa couplings can be derived. This relation leads to the prediction \tanβ\approx 14, where \tanβis the well known MSSM parameter. We find that this type of Yukawa coupling unification (YU) is realized only by employing non-universal soft supersymmetry breaking terms, dictated by SO(10) symmetry, for the gauginos. A 125 GeV Higgs boson mass is also found to be consistent with YU at the \sim 5% level. Without imposing a constraint on the relic abundance of dark matter in these models, the squark and slepton masses, with the exception of the stop, exceed 2 TeV and the gluino is heavier than 1 TeV. We show that the neutralino in this model is an acceptable dark matter candidate through the neutralino-stop coannihilation scenario, with the stop quark being relatively light (\gtrsim 500 GeV).

hep-ph↗

arXiv2013

A Predictive Yukawa Unified SO(10) Model: Higgs and Sparticle Masses

We revisit a class of supersymmetric SO(10) models with t-b-tau Yukawa coupling unification condition, with emphasis on the prediction of the Higgs mass. We discuss qualitative features in this model that lead to a Higgs mass prediction close to 125 GeV. We show this with two distinct computing packages, Isajet and SuSpect, and also show that they yield similar global features in the parameter space of this model. We find that t-b-tau Yukawa coupling unification prefers values of the CP-odd Higgs mass m_{A} to be around 600 GeV, with all colored sparticle masses above 3 TeV. We also briefly discuss prospects for testing this scenario with the ongoing and planned direct dark matter detection experiments. In this class of models with t-b-tau Yukawa unification, the neutralino dark matter particle is heavy (m_{\tildeχ_1^{0}} \gtrsim 400 \rm \ GeV), which coannihilates with a stau to yield the correct relic abundance.

hep-ph↗

arXiv2012

Revisiting mGMSB in light of a 125 GeV Higgs

We explore the implications of a 124-126 GeV CP-even Higgs boson on the fundamental parameter space and sparticle spectroscopy of the minimal gauge mediated supersymmetry breaking (mGMSB) scenario. The above mass for the Higgs boson yields stringent lower bounds on the sparticle masses in this class of models. The lightest neutralino and stau masses lie close to 1.5 TeV and 800 GeV respectively, while the majority of the sparticle masses are in the several to multi-TeV range. We show that with a single pair of 5+\bar{5} SU(5) messenger multiplets, the lower limit on the gravitino mass is \sim 360 eV. This is reduced to about 60 eV if five pairs of 5+\bar{5} messenger fields are introduced. Non-standard cosmology and non-standard gravitino production mechanisms are required in order to satisfy cosmological observations.

hep-ph↗

arXiv2012

Higgs Boson Production and Decay: Effects from Light Third Generation and Vectorlike Matter

We study the implications of light third generation sparticles on the production cross section and decay widths of a light CP-even Higgs boson. For simplicity, we consider scenarios in which only one of the sfermions from the third generation is light. For each case, we attempt to explain the apparently large enhancement in the Higgs production and decay in the diphoton channel with small deviations in the ZZ channel. In the MSSM framework we find that only a light stau can explain these observations while keeping the lightest CP-even Higgs boson mass in the interval 123 GeV \lesssim m_h \lesssim 127 GeV. For the light stop scenario, the observations related to the diphoton and ZZ channel can be accommodated but, in order to satisfy the Higgs mass bound, one needs to go beyond the MSSM. In particular, we invoke vector like particles with masses around a TeV. These new particles preserve gauge coupling unification and provide additional contributions to the Higgs mass. With these new contributions a 126 GeV Higgs mass is easily achieved. We also find that with only a light sbottom quark, the above mentioned excess is hard to accommodate.

hep-ph↗

arXiv2011

Stop-Neutralino Coannihilation in the Light of LHC

We employ the ATLAS search results for events containing jets and large missing transverse momentum, corresponding to an integrated luminosity of 1 fb^{-1}, to investigate the constrained minimal supersymmetric model (CMSSM) with b-τYukawa coupling unification. In this scenario, one of the stops is the next-to-lightest supersymmetric particle (NLSP), which co-annihilates with the lightest (LSP) neutralino to yield the desired dark matter relic abundance. The NLSP stop, here taken to be lighter than the top quark, is slightly (<~ 20%-30%) heavier than the LSP neutralino, and it primarily decays into the LSP and a charm quark. We find that the multi-jets and monojet ATLAS searches are sensitive to this scenario if the stop pair production is accompanied by a hard QCD jet. The excluded limit for the NLSP stop mass from the ATLAS data can reach 160 GeV in the coannihilation region, with mass below 140 GeV essentially excluded. A significant region of the parameter space corresponding to large m_0 values, 8 TeV<~ m_0<~ 16 TeV, is excluded by our analysis. For LSP neutralino mass ~ 100 GeV, the LHC constraints in some cases on the spin-dependent (spin-independent) neutralino-nucleon cross section are significantly more stringent than the current and expected bounds from Xenon, CDMS and IceCube.

hep-ph↗

arXiv2011

LHC Constraints on NLSP Gluino and Dark Matter Neutralino in Yukawa Unified Models

The ATLAS experiment has recently presented its search results for final states containing jets and/or b-jet(s) and missing transverse momentum, corresponding to an integrated luminosity of 165 pb^{-1}. We employ this data to constrain a class of supersymmetric SU(4)_c X SU(2)_L X SU(2)_R models with t-b-τYukawa unification, in which the gluino is the next to lightest supersymmetric particle (NLSP). The NLSP gluino is slightly (~10-30%) heavier than the the LSP dark matter neutralino, and it primarily decays into the latter and a quark-antiquark pair or gluon. We find that NLSP gluino masses below ~300 GeV are excluded by the ATLAS data. For LSP neutralino mass ~200-300 GeV and μ>0, where μis the coefficient of the MSSM Higgs bilinear term, the LHC constraints in some cases on the spin-dependent (spin-independent) neutralino-nucleon cross section are significantly more stringent than the expected bounds from IceCube DeepCore (Xenon 1T/SuperCDMS). For μ<0, this also holds for the spin-dependent cross sections.

hep-ph↗

arXiv2011

Searching for NLSP Sbottom at the LHC

We study the collider phenomenology of sbottom-bino co-annihilation scenario at both the 7 TeV and 14 TeV LHC. This co-annihilation scenario requires that the NLSP sbottom and LSP bino masses are apart by no more than about 20% or so, and for M_{\tilde{b}_1}>M_b+M_{\tildeχ_1^0}, the sbottom decays exclusively into b+\tildeχ_1^0. We propose a search for sbottom pairs through b\bar{b} plus missing energy. By scanning the mass parameters M_{\tilde{b}_1} and M_{\tildeχ_1^0}, we investigate the discovery limits of sbottom and bino in the M_{\tilde{b}_1}-M_{\tildeχ_1^0} plane with at least 5σsignificance at the LHC, for varying integrated luminosities. It is shown that with at least 5 fb^{-1} luminosity, the 7 TeV LHC can explore a narrow region satisfying the 20% co-annihilation condition. For the 14 TeV LHC with 10 (100) fb^{-1} luminosity, the discovery limit of M_{\tilde{b}_1} is 360 (570) GeV.

hep-ph↗

arXiv2010

NLSP Gluino Search at the Tevatron and early LHC

We investigate the collider phenomenology of gluino-bino co-annihilation scenario both at the Tevatron and 7 TeV LHC. This scenario can be realized, for example, in a class of realistic supersymmetric models with non-universal gaugino masses and t-b-τYukawa unification. The NLSP gluino and LSP bino should be nearly degenerate in mass, so that the typical gluino search channels involving leptons or hard jets are not available. Consequently, the gluino can be lighter than various bounds on its mass from direct searches. We propose a new search for NLSP gluino involving multi-b final states, arising from the three-body decay \tilde{g}-> b\bar{b}\tildeχ_1^0. We identify two realistic models with gluino mass of around 300 GeV for which the three-body decay is dominant, and show that a 4.5 σobservation sensitivity can be achieved at the Tevatron with an integrated luminosity of 10 fb^{-1}. For the 7 TeV LHC with 50 pb^{-1} of integrated luminosity, the number of signal events for the two models is O(10), to be compared with negligible SM background event.

hep-ph↗

arXiv2009

Observable n - anti-n Oscillations with New Physics at LHC

We explore extensions of the MSSM in which TeV scale vector-like multiplets can mediate observable n-anti-n oscillations, without causing conflict with the proton decay experiments, with a U(1) symmetry playing an important role. The colored vector-like particles, in particular, may be found at the LHC through some decay modes arising from their direct couplings to quarks.

hep-ph↗