arXiv subjects

Girish Muralidhara

Publications and source records attributed to Girish Muralidhara.

7 recordsLinked to original sources

arXiv2026

Direct detection of electromagnetically interacting ultraheavy dark matter

At a level too faint for astronomy, particle dark matter may interact with Standard Model states via the photon. We derive limits from direct detection experiments on photon-mediated nuclear interactions up to operator dimension-6, viz., via a millicharge, charge radius, electric and magnetic dipole moment, and anapole moment, up to dark matter masses $\lesssim 10^{17}$ GeV, where detectors become flux-limited. We derive constraints for XENON1T, XENONnT, LZ, PANDAX-II, PANDAX-4T, DarkSide-50, DEAP-3600, PICO-60, and CDMS-II, and estimate future sensitivities for the multi-deca-tonne scale experiments DarkSide-20k, DARWIN/XLZD, PANDAX-xT, and Argo. Special attention is paid to millicharged dark matter, for which we constrain new parameter space by deriving the ceiling on sensitivity to its electric charge, arising from the nuclear-vs-electron recoil discriminants used in liquid argon and bubble chamber detectors. This result goes beyond ceilings previously identified in liquid xenon and semiconductor detectors from electron recoil vetoes. In particular, the ceiling from PICO-60 closes a large window between direct detection and neutrino experiment limits for dark matter masses below $10^{12}$ GeV.

hep-ph↗

arXiv2026

Hadronic parity violation: successes, challenges, and future prospects

Hadronic parity violation concerns the study of the interplay of the weak- and strong-interaction dynamics that yields low energy, parity-violating observables in systems of hadrons and nuclei. We explain its essential features, as well as our current understanding of its observed effects, describing recent theoretical and experimental progress in a pedagogical context. We provide a broad overview of ongoing research efforts to show how precision studies of few-nucleon systems can be extended to studies of complex nuclei and, ultimately, to new benchmarks for computations in the Standard Model, as well as to new searches for the dynamics beyond it.

nucl-th↗

arXiv2023

$ΔS=0$ Hadronic Parity Violation in Next-to-Leading Order QCD: Anomalous Dimension Matrices and Their Implications

We construct the effective Hamiltonian for hadronic parity violation in strangeness-nonchanging ($ΔS=0$) processes in next-to-leading order (NLO) in QCD, for all isosectors, and at a renormalization scale of 2 GeV, thus extending our earlier leading-order (LO) analysis. Hadronic parity violation, studied in the context of the low-energy interactions of nucleons and nuclei, exposes the complex interplay of weak and strong interactions in these systems, and thus supports our extension to NLO. Here we exploit the flavor-blind nature of QCD interactions to construct the needed anomalous dimension matrices from those computed in flavor physics, which we then use to refine our effective Hamiltonian and finally our predicted parity-violating meson-nucleon coupling constants, to find improved agreement with few-body experiments.

hep-ph↗

arXiv2023

Towards a unified treatment of $ΔS=0$ parity violation in low-energy nuclear processes

We revisit the unified treatment of low-energy hadronic parity violation espoused by Desplanques, Donoghue, and Holstein to the end of an ab initio treatment of parity violation in low-energy nuclear processes within the Standard Model. We use our improved effective Hamiltonian and precise non-perturbative assessments of the quark charges of the nucleon within lattice QCD to make new assessments of the parity-violating meson-nucleon coupling constants. Comparing with recent, precise measurements of hadronic parity violation in few-body nuclear reactions, we find improved agreement with these experimental results, though some tensions remain. We thus note the broader problem of comparing low-energy constants from nuclear and few-nucleon systems, considering, too, unresolved theoretical issues in connecting an ab initio, effective Hamiltonian approach to chiral effective theories. We note how future experiments and lattice QCD studies could sharpen the emerging picture, promoting the study of hadronic parity violation as a laboratory for testing ``end-to-end'' theoretical descriptions of weak processes in hadrons and nuclei at low energies.

nucl-th↗

arXiv2022

QCD Analysis of $ΔS=0$ Hadronic Parity Violation

We present a QCD analysis of the effective weak Hamiltonian at hadronic energy scales for strangeness-nonchanging ($ΔS=0$) hadronic processes. Performing a leading-order renormalization group analysis in QCD from the $W$ to the ${\cal O}(2\,\rm GeV)$ energy scale, we derive the pertinent effective Hamiltonian for hadronic parity violation, including the effects of both neutral and charged weak currents. We compute the complete renormalization group evolution of all isosectors and the evolution through heavy-flavor thresholds for the first time. We show that the additional four-quark operators that enter below the $W$ mass scale from QCD operator mixing effects form a closed set, and they result in a $12\times 12$ anomalous dimension matrix. Computing the resulting effective Hamiltonian and comparing to earlier results, we affirm the importance of operator mixing effects and find, as an example, that the parity-violating pion-nucleon coupling constant, using the factorization Ansatz and an assessment of the pertinent quark charge of the nucleon in lattice QCD at the 2 GeV scale, is in better agreement with recent experiments.

hep-ph↗

arXiv2020

Universal RCFT Correlators from the Holomorphic Bootstrap

We elaborate and extend the method of Wronskian differential equations for conformal blocks to compute four-point correlation functions on the plane for classes of primary fields in rational (and possibly more general) conformal field theories. This approach leads to universal differential equations for families of CFT's and provides a very simple re-derivation of the BPZ results for the degenerate fields $ϕ_{1,2}$ and $ϕ_{2,1}$ in the c < 1 minimal models. We apply this technique to compute correlators for the WZW models corresponding to the Deligne-Cvitanović exceptional series of Lie algebras. The application turns out to be subtle in certain cases where there are multiple decoupled primaries. The power of this approach is demonstrated by applying it to compute four-point functions for the Baby Monster CFT, which does not belong to any minimal series.

hep-th↗

arXiv2016

Manifestation of pointer state correlations in complex weak values of quantum observables

In the weak measurement (WM) scenario involving weak interaction and postselection by projective measurement, the empirical significance of weak values is manifested in terms of shifts in the measurement pointer's mean position and mean momentum. In this context, a general quantitative treatment is presented in this paper by taking into account the hitherto unexplored effect of correlations among the pointer degrees of freedom which pertain to an arbitrary multidimensional preselected pointer state. This leads to an extension of the earlier results, showing that, for complex weak values, the correlations among different pointer degrees of freedom can crucially affect the way the imaginary parts of the weak values are related to the observed shifts of the mean pointer position and momentum. The particular relevance of this analysis is discussed in the case of sequential weak interactions, followed by a postselection (called sequential WM) which, in the special case, reduces to the usual WM scheme involving a single weak interaction and postseletion, modified by the effect of pointer state correlations.

quant-ph↗