Large-$N_c$ and renormalization group constraints on parity-violating low-energy coefficients for three-derivative operators in pionless effective field theory
Son T. Nguyen, Matthias R. Schindler, Roxanne P. Springer, Jared Vanasse
We extend from operators with one derivative to operators with three derivatives the analysis of two-body hadronic parity violation in a combined pionless effective field theory (EFT$_{π\!/}$) and large-$N_c$ expansion, where $N_c$ is the number of colors in quantum chromodynamics (QCD). In elastic scattering, these operators contribute to $S$-$P$ and $P$-$D$ wave transitions, with five operators and their accompanying low energy coefficients (LECs) characterizing the $S$-$P$ transitions and six operators and LECs those in $P$-$D$ transitions. We show that the large-$N_c$ analysis separates them into leading order in $N_c$, next-to-leading order in $N_c$, etc. Relationships among EFT$_{π\!/}$ LECs emerge in the large-$N_c$ expansion. We also discuss the renormalization scale dependence of these LECs. Our analysis can complement lattice QCD calculations and help prioritize future parity-violating experiments.
The symmetries of the Standard Model dictate that for very low energies, where nucleon dynamics can be described in terms of a pionless effective field theory, the leading-order parity-violating nucleon-nucleon Lagrangian contains five independent unknown low-energy constants (LECs). We find that imposing the approximate symmetry of QCD that appears when the number of colors N(c) becomes large reduces the number of independent LECs to two at leading order in the combined pionless effective field theory and large-N(c) expansions. We also find a relation between the two isoscalar LECs in the lar…
We consider parity-violating observables from the processes $\vec n p\to d γ$ and $ np \to d \overset {\circlearrowleft}γ$. We perform calculations using pionless effective field theory both with and without explicit dibaryon fields. After combining these results with ones we have already obtained on parity-violating asymmetries in $\vec NN$ scattering, experimental input would in principle allow the extraction of all five parameters occurring at leading order in the parity-violating Lagrangian.
We consider the two-nucleon weak interaction with a pionless effective field theory. Dibaryon fields are introduced to facilitate calculations and ensure precision in the initial and final state propagators. Weak interactions are accounted for with the parity-violating dibaryon-nucleon-nucleon vertices, which contain unknown weak dibaryon-nucleon-nucleon coupling constants. We apply the model to the calculation of a parity-violating observable in the neutron-proton capture at threshold. Result is obtained up to the linear order in the unknown dibaryon-nucleon-nucleon coupling constants. We com…
We calculate the parity-violating amplitudes in the nd interaction with pionless effective field theory to LO. Matching the parity violating low energy constants to the DDH coefficients we make numerical predictions for parity-violating observables. In particular we give predictions for the spin rotation of a neutron on a deuteron target, and target and beam asymmetries in nd scattering.
Nuclear electric dipole moments of $^{3}He$ and $^{3}H$ are calculated using Time Reversal Invariance Violating (TRIV) potentials based on the meson exchange theory, as well as the ones derived by using pionless and pionful effective field theories, with nuclear wave functions obtained by solving Faddeev equations in configuration space for the complete Hamiltonians comprising both TRIV and realistic strong interactions. The obtained results are compared with the previous calculations of $^{3}He$ EDM and with time reversal invariance violating effects in neutron-deuteron scattering.
Time reversal invariance violating parity conserving (TVPC) effects are calculated for elastic proton deuteron scattering with proton energies up to $2~$MeV. Distorted Wave Born Approximation is employed to estimate TVPC matrix elements, based on hadronic wave functions, obtained by solving three-body Faddeev-Merkuriev equations in configuration space with realistic potentials.
We calculate $γZ$ exchange corrections to the parity-violating asymmetry of the elastic electron-proton scattering in a parton model using the formalism of generalized parton distributions(GPDs). We also examine the validity of the zero-momentum-transfer approximation adopted in the literatures and find that it overestimates the $γZ$ exchange effect significantly at the forward scattering angles.
In this lecture, I review progress made in the calculations of the parity-violating meson-nucleon interaction regions. The underlying framework is the topological chiral soliton model of the nucleon. Emphasis is put on the computation of theoretically and experimentally accessible nuclear parity violating observables. I stress the importance of the interplay of strong and weak interactions which makes this field interesting and challenging. I also discuss recent developments pointing towards the importance of strange quark admixtures in the proton wave function. (Invited talk presented at the …
We present a new contribution of the R-parity violating supersymmetry (SUSY) to neutrinoless double beta decay via the pion exchange between decaying neutrons. The pion coupling to the final state electrons is induced by the R-parity violating SUSY interactions. We have found this pion-exchange mechanism to dominate over the conventional two-nucleon one. The latter corresponds to direct interaction between quarks from two decaying neutrons without any light hadronic mediator like pion. The constraints on the certain R-parity violating SUSY parameters are extracted from the current experimental…
We study the parity-violating alpha+d decay of the lowest 0+ state of Li-6 in a microscopic three-cluster model. The initial bound and the final scattering states are described consistently within the same model. The parity-violating decay width is calculated in perturbation theory using the parity-nonconserving nucleon-nucleon interaction of Desplanques, Donoghue, and Holstein (DDH). We find that the decay width is sensitive to dynamical degrees of freedom which are beyond the alpha+p+n model, for example, alpha excitation and breakup. In our full model, which contains breathing excitations o…
I present the calculation of parity- and time-reversal-violating moments of the nucleon and light nuclei, originating from the QCD theta term and effective dimension-six operators. By applying chiral effective field theory these calculations are performed in a unified framework. I argue that measurements of a few light-nuclear electric dipole moments would shed light on the mechanism of parity and time-reversal violation.
Weak interactions are expected to induce a parity violating pion-nucleon coupling, h_{πNN}^{(1)}. This coupling should be measurable in a proposed experiment to study the parity violating asymmetry A_γin the process \vec n + p \to d+γ. We compute the leading dependence of A_γon the coupling h_{πNN}^{(1)} using recently developed effective field theory techniques and find an asymmetry of A_γ= +0.17 h_{πNN}^{(1)} at leading order. This asymmetry has the opposite sign to that given by Desplanques, Donoghue and Holstein.
We show that the present experimental limits on electron-nucleon interactions that violate both parity and time reversal invariance provide new stringent bounds on the imaginary parts of some of the products of the R-parity violating coupling constants in the R-parity violating Minimal Supersymmetric Standard Model.
The effect of vacuum polarization on the parity violating asymmetry in the elastic electron-nucleus scattering is considered. Calculations are performed in the high-energy approximation with an exact account for the electric field of the nucleus. It is shown that the radiative correction to the parity violating asymmetry is logarithmically enhanced and the value of the correction is about -1%.
The effects of charge symmetry breaking in nucleon electromagnetic form factors on parity- violating elastic electron-12C scattering is studied, and found to be much smaller than other known effects. The analysis of a planned experiment is discussed.
We compute the supersymmetric (SUSY) corrections to the parity-violating, deep inelastic electron-deuteron asymmetry. Working with the Minimal Supersymmetric Standard Model (MSSM) we consider two cases: R parity conserving and R parity-violating. Under these scenarios, we compare the SUSY effects with those entering other parity-violating observables. For both cases of the MSSM, we find that the magnitude of the SUSY corrections can be as large as about 1% and that they are strongly correlated with the effects on other parity-violating observables. A comparison of various low-energy parity-vio…
We review the area of strange quark contributions to nucleon structure. In particular, we focus on current models of strange quark vector currents in the nucleon and the associated parity-violating elastic electron scattering experiments from which vector- and axial-vector currents are extracted
Weak interactions in two-nucleon system at low energies are explored in the framework of effective field theory. We review our recent calculations of parity-violating observables in radiative neutron capture on a proton at threshold where both pionful and pionless theories are employed.
We present a comprehensive analysis of gamma-Z interference corrections to the weak charge of the proton measured in parity-violating electron scattering, including a survey of existing models and a critical analysis of their uncertainties. Constraints from parton distributions in the deep-inelastic region, together with new data on parity-violating electron scattering in the resonance region, result in significantly smaller uncertainties on the corrections compared to previous estimates. At the kinematics of the Qweak experiment, we determine the gamma-Z box correction to be ReBox^V_{gamma-Z}…
We study one-loop contributions to the fermion electric dipole moments in the Minimal Supersymmetric Standard Model with explicit R-parity violating interactions. We obtain new individual bounds on R-parity violating Yukawa couplings and put more stringent limits on certain parameters than those obtained previously.
We summarized our report on leptonic flavor violating Higgs decay into mu + tau under the scheme of a generic supersymmetric standard model without R parity. With known experimental constraints imposed, important combinations of R-parity violating parameters which can give notable branching ratios are listed.
We use the precision electroweak data at LEP to place bounds on $B$-violating Yukawa couplings, two theoretically appealing examples being provided by $R$-parity--violating supersymmetry and diquarks. The couplings involving the third generation quarks are most severely constrained. These bounds are complementary to those obtained from low-energy processes.
Parity violating elastic electron-nucleus scattering provides an accurate and model independent measurement of neutron densities, because the $Z^0$ couples primarily to neutrons. Coulomb distortion corrections to the parity violating asymmetry $A_l$ are calculated exactly using a relativistic optical model. Distortions significantly reduce $A_l$ in a heavy nucleus. However even with distortions, an experiment to measure the neutron radius is feasible. This will aid the interpretation of future atomic parity violation measurements and provide fundamental nuclear structure information. Coulomb d…
We have developed an efficient formulation for the study of the generic supersymmetric standard model, which admits all kind of R-parity violating terms. Using the formulation, we discuss all sources of fermion dipole moment contributions from R-parity violating, or rather lepton number violating, parametersand the constraints obtained. Stringent constraints comparable to those from neutrino masses are resulted in some cases.
We present the two-loop $β$-functions for non-standard soft supersymmetry-breaking couplings including non-standard R-parity violating soft terms in the Minimal Supersymmetric Standard Model
We study CP violating B decays in the minimal supersymmetric standard model with R-parity violation. We estimate how much R-parity violation modifies the SM predictions for CP asymmetries in B decays within the present bounds. The effects of R-parity- and lepton-number-violating couplings on the ratio of the decay amplitude due to R-parity violation to that of the SM can differ by one or two orders of magnitudes depending on the models of the left-handed quark mixing. It is possible to disentangle the R-parity violating effects from those of the SM and R-parity- conserving supersymmetric model…
The contribution of the R-parity violating minimal supersymmetric standard model to the neutron beta decay at the one-loop level is investigated. It is found that the baryon number and R-parity violating interactions contribute to the D correlation through one-loop corrections, while the tree level prediction is vanishing. The Fierz interference term is also investigated at the one-loop level by considering the lepton number and R-parity violating interactions. We show that future experimental progress can provide us with better constraints on some of the combinations of R-parity violating cou…
We investigate the possible role that baryon number violating Yukawa interactions may take in the inclusive decay $ B \to X_s γ$. The constraints, derived using the experimental results of the CLEO collaboration, turn out, in many cases, to be more stringent than the existing bounds.
Recent measurements of CP asymmetry in B --> phi K_S appear to be inconsistent with Standard Model expectations. We explore the effect of R-parity-violating SUSY to understand the data.
The lepton number violating process $μ\rightarrow eγ$ is used to study the lepton number violating couplings in MSSM extended by terms violating $R$-parity explicitly. Bounds are obtained for the products of $λ$- or $λ'$-type couplings. It is found that many of these limits are more stringent than the ones obtained previously.
The effective Hamiltonian for the R-parity violating couplings induced nonleptonic decay $B^-\to K^-K^0$ is calculated including leading log QCD corrections running from $m_{\tilde q}$, the mass of the up-type squark, to $m_b$. Experimental upper limit of this decay is used to give the bound on the R-parity violating couplings $λ''$.
Parity-violating asymmetries in polarized electron scattering have been interpreted as the asymmetries between opposite helicities of incoming fermion based on the approximation of the spin polarization operator. Here exact calculations of cross sections for parity-violating asymmetries in SLAC E158 and SLD have been performed using spin projection operators. And the parity-violating factor incorporating with spin polarization and momentum has been identified and shown that its sign depends on the spin polarization of incoming particle and the relative velocity of incoming and target particles…
We present the full two-loop beta-functions for the MSSM including R-parity violating couplings. We analyse the effect of two-loop running on the bounds on R-parity violating couplings, on the nature of the LSP and on the stop masses.
Parity-violating nuclear force, as may be accessed from parity violation studies in nuclear systems, represents an area of nonleptonic weak interactions which has been the subject of experimental investigations for several decades. In the simple meson-exchange picture, parity-violating nuclear force may be parameterized as arising from exchange of π, ρ, ω, or other meson(s) with strong meson-nucleon coupling at one vertex and weak parity-violating meson-nucleon coupling at the other vertex. The QCD sum rule method allows for a fairly complicated, but nevertheless straightforward, leading-order…
$D$- and $τ$-decays are used to place bounds on some $R$-parity--violating $λ'$-type Yukawa interactions. Some of these bounds are competitive with the existing ones, some are improved while some are new.
We study in the framework of R-parity violating supersymmetric theories the effect of R-parity violation due to the operator L_i L_j \bar{E_k} on the (V-A) structure of the muon decay. The precisely measured muon decay parameters can constrain a product of R-parity violating couplings: |λ_{232}λ_{131}| < 0.022 at the 90% CL, which is complementary to the previous limits obtained by the e-μuniversality in τdecay.
It is shown that in R-parity violating models of supersymmetry, the CP violation observed in the kaon system could arise purely from the R-parity violating scalar interactions (A-terms), with no CP violation in the CKM matrix. The direct CP violating parameter, epsilon', could be as large or larger than that expected in the Standard Model. CP violation in the B system however is expected to be negligible.
We investigate the parity-violating $πNN$ Yukawa coupling constant $h^1_{πNN}$ within the framework of the SU(2) chiral quark-soliton model, based on the $ΔS=0$ effective weak Lagrangian derived within the same framework. We find that the parity-violating $πNN$ coupling constant is about $1\times10^{-8}$ at the scale of 1 GeV. The results of $h_{πNN}^1$ turn out to be sensitive to the Wilson coefficient. We discuss how the gluonic renormalization supresses the parity-violating $πNN$ coupling constant.
We consider the neutrino oscillations within the minimal supersymmetric standard model with R-parity violation. The Super-Kamiokande atmospheric neutrino data are used to set limits on the bilinear R-parity violating terms. These very stringent limits are out of reach of the other experiments at present and in the near future.
We perform a systematic reevaluation of the constraints on the flavor-changing neutral current (FCNC) parameters in R-parity conserving and R-parity violating supersymmetric models. As a typical process, we study the constraints coming from the measurements on the B0-\bar{B0} system on the supersymmetric $δ^d_{13}$ parameters, as well as on the products of the lambda' type R-parity violating couplings. Present data allows us to put constraints on both the real and the imaginary parts of the relevant parameters.
In an R-parity-violating supersymmetric theory, we derive upper bounds on all the λ''_{ijk}λ_{i'j'k'}-type combinations from the consideration of proton stability, where λ''_{ijk} are baryon-number-violating couplings involving three baryonic fields and λ_{i'j'k'} are lepton-number-violating couplings involving three leptonic fields.
We update the bounds on $R$-parity violating supersymmetry originating from meson oscillations in the $B^0_{d/s}$ and $K^0$ systems. To this end, we explicitly calculate all corresponding contributions from $R$-parity violating operators at the one-loop level, thereby completing and correcting existing calculations. We apply our results to the derivation of bounds on $R$-parity violating couplings, based on up-to-date experimental measurements. In addition, we consider the possibility of cancellations among flavor-changing contributions of various origins, e.g. from multiple $R$-parity violati…
We present a reanalysis of nucleon decay in the context of the R-parity violating MSSM, updating bounds on R-parity violating parameters against recent experimental and lattice results. We pay particular attention to the derivation of these constraints and specifically to the hadronic matrix elements, which usually stand as the limiting factor in order to derive reliable bounds, except for these few channels that have been studied on the lattice.
The contribution of the R-parity violating trilinear couplings in the supersymmetric model to the fermion electric dipole moment is analyzed at the two-loop level. We show that in general, the Barr-Zee type contribution to the fermion electric dipole moment with the exchange of W and Z bosons is not small compared to the currently known photon exchange one with R-parity violating interactions. We will then give new upper bounds on the imaginary parts of R-parity violating couplings from the experimental data of the electric dipole moments of the electron and of the neutron. The effect due to b…
Motivated by the recent experimental data of the E787, E949 and E865 collaborations and by the difference between the standard model (SM) prediction and data, we consider in detail R-parity violating (RPV) supersymmetric contributions to K -> pi nu nubar. The theoretical cleaness of this decay constitutes a useful way to provide constraints, independent of long distance effects. Including the possiblity of interferences between one-loop R-parity conserving (RPC) supersymmetry and tree-level RPV supersymmetric contributions, our results allow to improve the limits on R-parity violating coupling…
The contribution of the R-parity violating minimal supersymmetric Standard model (RPVMSSM) at the one-loop level to the 199Hg atomic electric dipole moment (EDM) through P, CP-odd electron-nucleon (e-N) interaction is calculated. We show that the current experimental data of the 199Hg EDM give tighter constraints on some of the imaginary parts of R-parity violating (RPV) coupling than those currently known. We add also the analysis of the P, CP-odd 4-quark interaction generated by R-parity violating interactions at the one-loop level, and discuss the possibility to constrain them in future exp…
Assuming the lightest supersymmetric particle is the gluino, we treat the decays gluino->quark-antiquark-neutrino and gluino->gluon-neutrino. Such couplings can be induced by the R parity violating quark-squark-lepton interaction which can also be responsible for neutrino masses and mixings. These R parity violating gluino decays have the same final state structure (jets plus missing energy) as previously considered decays into quark-antiquark-photino and gluon-gravitino but with significantly different gluino lifetimes.
We investigate the ability of single top quark production via qq'-> squark->tb and q \bar q'->slepton->t\bar b at the LHC and Tevatron to probe the strength of R-parity violating couplings in the minimal supersymmetric model. We found that given the existing bounds on R-parity violating couplings, single top quark production may be greatly enhanced over that predicted by the standard model, and that both colliders can either discover R-parity violating SUSY or set strong constraints on the relevant R-parity violating couplings. We further found that the LHC is much more powerful than the Tevat…
Yukawa-like R-parity violating (RPV) couplings are generated as effective operators with a typical strength of ${\cal O}(10^{-3})$ through loops involving the scalars, the gauginos and the soft supersymmetry breaking RPV interactions. Neutrino masses and other phenomenological implications of such a scenario are discussed.
The nontrivial structure of the neutrino mass matrix, suggested by the recent Super-Kamiokande results and data from other neutrino experiments, can be reproduced in R-parity-violating supersymmetric theories. This requires sets of products of R-parity-violating trilinear couplings to take appropriately chosen values. It is shown that the existing constraints on these couplings are satisfied by these choices.
We derive the upper bounds on certain products of R-parity- and lepton-flavor-violating couplings from $B^\pm \to l^\pm ν$ decays. These modes of B-meson decays can constrain the product combinations of the couplings with one or more heavy generation indices which are comparable with or stronger than the present bounds. And we investigate the possible effects of R-parity violating interactions on $B_c \to l ν$ decays. These decay modes can be largely affected by R-parity violation.
We present a study of charged lepton mass matrix diagonalization in R-parity violating SUSY. The case in which the bilinear couplings $μ_i$ have large values is given special attention.
Bounds on R-parity violating couplings in the supersymmetric standard model are reviewed, and some new bounds arising from non-observation of certain rare B-decays (such as $B \rightarrow K^+K^-$) are presented. The focus is on baryon-number violating couplings, but it is also noted that many products of lepton- number violating and baryon-number violating couplings are not significantly constrained by proton decay bounds. The talk reviewed the work in a recent paper by Carlson, Roy and Sher (Phys. Letters, in press).
We report on a calculation of one-loop weak corrections to polarized quark-gluon scattering and the corresponding crossed channels. Such contributions are suppressed formally by one power of alpha_s relative to W- or Z-mediated quark-quark scattering, but would enable the spin asymmetry of the gluon distribution to contribute to parity-violating asymmetries that will soon be investigated in polarized proton-proton scattering experiments at RHIC. In certain kinematic regions, gluon contributions to parity-violating asymmetries can be as large as 10% of the tree-level W- and Z-exchanges in quark…
Parity violating left-right scattering asymmetries at future high energy e+e- and e-e- colliders are examined. The utility of two polarized beams for precision measurements is pointed out. Sensitivity to ``new'' short-distance physics is briefly discussed. Electroweak radiative corrections due to the running of sin^2(theta_W)(q^2) are exhibited.
