arXiv subjects

Hindi Zouhair

Publications and source records attributed to Hindi Zouhair.

4 recordsLinked to original sources

arXiv2026

Lifting Effective-Field-Theory Degeneracies in Semileptonic Heavy-Baryon Decays

Semileptonic heavy-baryon decays provide a sensitive probe of the helicity structure underlying possible lepton-flavor universality violation in $b\to c\,τ\barν_τ$ transitions. We perform an effective-field-theory analysis of $Λ_b\toΛ_cτ\barν_τ$ and related baryonic modes using lattice-QCD helicity form factors with full covariance propagation. Propagating meson-compatible EFT solutions into the baryonic observable space$(R_{Λ_c},\,P_τ,\,A_{\rm FB})$, we show that tau polarization provides the leading source of sensitivity for lifting EFT degeneracies that remain unresolved in current measurements of $R(D)$ and $R(D^\ast)$. Vector-like and tensor-like solutions remain clustered near theStandard-Model prediction, whereas scalar-containing directions produce large polarization displacements and characteristic low-$q^2$ deformations of the normalized differential spectrum. A covariance-aware analysis demonstrates that baryonic polarization and differential observables provide complementary and independent information on the Lorentz structure of semileptonic new physics. $P_τ(Λ_b\toΛ_cτ\barν_τ)$ and the low-$q^2$ spectrum as particularly powerful probes for future tests of semitauonic flavor anomalies at LHCb and future flavor facilities.

hep-ph↗

arXiv2026

Null Tests and Lepton Universality in $Ξ_{cc}$ Baryon Decays

We develop a precision framework for doubly charmed baryon decays based on symmetry-protected observables and effective-field-theory diagnostics. In nonleptonic $Ξ_{cc}$ decays, we construct a null combination of widths that vanishes in the heavy-diquark factorization limit, providing a direct probe of nonfactorizable QCD dynamics. For semileptonic decays, we identify the light-lepton universality ratio $R_{Ξ_c}^{μe}$ as an observable in which leading hadronic normalization cancels at the amplitude level, yielding direct sensitivity to short-distance charged-current interactions. Percent-level precision probes $|C_{V_L}^μ|\sim \mathcal{O}(10^{-2})$, whereas $\mathcal{O}(10^{-1})$ deformations induce order-one deviations. Scalar contributions remain parametrically suppressed. Combining baryonic and mesonic inputs, we show that $Ξ_{cc}$ decays constrain the same short-distance interaction with complementary scaling, lifting degeneracies inherent to meson-only analyses. Mapping to a charged-vector benchmark demonstrates sensitivity to multi-TeVnew-physics scales. These results establish doubly charmed baryons as an independent probe of charged-current interactions beyond the Standard Model.

hep-ph↗

arXiv2026

Global Electroweak Fit Constraints on the Two-Higgs-Doublet Model in Light of the CDF W -Boson Mass

The recent measurement of the $W$ boson mass by the CDF II collaboration exhibits a significant tension with the Standard Model (SM) prediction and other experimental determinations. In this work, we investigate the implications of this result within the framework of the Two-Higgs-Doublet Model (2HDM), focusing on radiative corrections to electroweak precision observables parameterized in terms of the oblique parameters $ΔS$, $ΔT$, and $ΔU$. Using global electroweak fits, we analyze how the inclusion of the CDF measurement modifies the preferred parameter space. We show that the observed shift in $m_W$ can be accommodated in the 2HDM through enhanced contributions to $ΔT$, arising from mass splittings in the scalar sector. The resulting constraints on the scalar spectrum are presented and compared with those obtained using previous electroweak data. These results highlight the role of precision observables in probing extended Higgs sectors and provide updated bounds on viable 2HDM parameter space.

hep-ph↗

arXiv2026

Dark matter relic abundance from a critical-density instability

We study a nonstandard dark-matter thermal history in which strong self-interactions give rise to collective many-body effects at high number density, as in strongly interacting quantum media. At early times, dark matter occupies a correlated phase in which its coupling to a light mediator is dynamically screened, suppressing annihilation far below the perturbative rate. As the Universe expands and the number density decreases, this screened phase becomes unstable at a critical density n_c, triggering a rapid, far-from-equilibrium annihilation episode. We show that this annihilation burst fixes the final relic abundance, which is governed primarily by n_c rather than by the microscopic annihilation coupling. Using a minimal effective parametrization, we solve the resulting modified Boltzmann evolution and map the viable parameter space. For TeV-scale dark matter and sub-GeV mediators, we find relic abundances consistent with observations together with self-interaction cross sections relevant for small-scale structure, realizing a consistent and predictive nonstandard thermal history.

hep-ph↗