Andriy Kurylov

Generalized analysis of the direct weakly interacting massive particle searches

We perform a generalized analysis of data from WIMP search experiments for pointlike WIMPs of arbitrary spin and general Lorenz-invariant WIMP-nucleus interaction. We explicitly show that in the nonrelativistic limit only spin-independent (SI) and spin-dependent (SD) WIMP-nucleon interactions survive, which can be parametrized by only five independent parameters. We explore this five-dimensional parameter space to determine whether the annual modulation observed in the DAMA experiment can be consistent with all other experiments which reported null results. The pure SI interaction is ruled out except for a very small region of parameter space with the WIMP mass close to 50 GeV and the ratio of the WIMP-neutron to WIMP-proton SI couplings –0.77<=fn/fp<=–0.75. For the predominantly SD interaction, we find an upper limit on the WIMP mass of about 18 GeV, which can only be weakened if the constraint stemming from null searches for energetic neutrinos from WIMP annihilation the Sun is evaded. None of the regions of the parameter space that can reconcile all WIMP search results can be easily accommodated in the minimal supersymmetric standard model.

The Weak charge of the proton and new physics

We address the physics implications of a precise determination of the weak charge of the proton, QW(p), from a parity violating elastic electron proton scattering experiment to be performed at the Jefferson Laboratory. We present the standard model (SM) expression for QW(p) including one-loop radiative corrections, and discuss in detail the theoretical uncertainties and missing higher order QCD corrections. Owing to a fortuitous cancellation, the value of QW(p) is suppressed in the SM, making it a unique place to look for physics beyond the SM. Examples include extra neutral gauge bosons, supersymmetry, and leptoquarks. We argue that a QW(p) measurement will provide an important complement to both high energy collider experiments and other low energy electroweak measurements. The anticipated experimental precision requires the knowledge of the O(alphas) corrections to the pure electroweak box contributions. We compute these contributions for QW(p), as well as for the weak charges of heavy elements as determined from atomic parity violation.

New Contribution to Scattering of Weakly Interacting Massive Particles on Nuclei

A weakly-interacting massive particle (WIMP) is perhaps the most promising candidate for the dark matter in the Galactic halo. The WIMP detection rate in laboratory searches is fixed by the cross section for elastic WIMP-nucleus scattering. Here we calculate the contribution to this cross section from two-nucleon currents from pion exchange in the nucleus, and show that it may in some cases be comparable to the one-nucleon current that has been considered in prior work, and perhaps help resolve the discrepancies between the various direct dark-matter search experiments. We provide simple expressions that allow these new contributions to be included in current calculations.

Lepton flavor violation without supersymmetry

We study the lepton flavor-violating (LFV) processes µ-->egamma, µ-->3e, and µ-->e conversion in nuclei in the left-right symmetric model without supersymmetry and perform the first complete computation of the LFV branching ratios B(µ-->f) to leading nontrivial order in the ratio of left- and right-handed symmetry-breaking scales. To this order, B(µ-->egamma) and B(µ-->e) are governed by the same combination of LFV violating couplings, and their ratio is naturally of order unity. We also find B(µ-->3e)/B(µ-->e)~100 under slightly stronger assumptions. Existing limits on the branching ratios already substantially constrain mass splittings and/or mixings in the heavy neutrino sector. When combined with future collider studies and precision electroweak measurements, improved limits on LFV processes will test the viability of low-scale, nonsupersymmetric LFV scenarios.

Probing supersymmetry with parity-violating electron scattering

We compute the one-loop supersymmetric (SUSY) contributions to the weak charges of the electron (

Spatial variation of the fine-structure parameter and the cosmic microwave background

Q_W^e

Radiative corrections in neutrino-deuterium disintegration

) and proton (

Radiative corrections to low-energy neutrino reactions

Q_W^p

Supersymmetric effects in deep inelastic neutrino nucleus scattering

) using the Minimal Supersymmetric Standard Model (MSSM). These

Supersymmetric effects in parity-violating deep inelastic electron-nucleus scattering

q^2=0