QCD running in neutrinoless double beta decay: Short-range mechanisms

González, Marcela; Hirsch, Martin; Kovalenko, Sergey

doi:10.1103/physrevd.93.013017

Cited by 29 publications

(41 citation statements)

References 31 publications

(55 reference statements)

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“…These matrix elements, once incorporated into nuclear decay rate calculations, can be used to place limits on the various BSM mechanisms that give rise to 0νββ, see for example [22,23,[77][78][79][80][81][82][83][84][85][86]. The limits on the BSM mechanisms must also account for the running of these short distance operators, which can modify their strength by an amount comparable to the current uncertainties on the nuclear matrix elements themselves [87]. Modern analyses use Effective Field Theory [22,23,85,86], for which this contribution is the leading order shortrange correction.…”

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confidence: 99%

Heavy Physics Contributions to Neutrinoless Double Beta Decay from QCD

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Observation of neutrinoless double beta decay, a lepton number violating process that has been proposed to clarify the nature of neutrino masses, has spawned an enormous world-wide experimental effort. Relating nuclear decay rates to high-energy, beyond the Standard Model (BSM) physics requires detailed knowledge of non-perturbative QCD effects. Using lattice QCD, we compute the necessary matrix elements of short-range operators, which arise due to heavy BSM mediators, that contribute to this decay via the leading order π − → π + exchange diagrams. Utilizing our result and taking advantage of effective field theory methods will allow for model-independent calculations of the relevant two-nucleon decay, which may then be used as input for nuclear many-body calculations of the relevant experimental decays. Contributions from short-range operators may prove to be equally important to, or even more important than, those from long-range Majorana neutrino exchange.Introduction.-Neutrinoless double beta decay (0νββ) is a process that, if observed, would reveal violations of symmetries fundamental to the Standard Model, and would guarantee that neutrinos have nonzero Majorana mass [1, 2]. Such decays can probe physics beyond the electroweak scale and expose a source of leptonnumber (L) violation which may explain the observed matter-antimatter asymmetry in the universe [3,4]. Existing and planned experiments will constrain this novel nuclear decay [5][6][7][8][9][10][11][12][13][14][15][16], but the interpretation of the resulting decay rates or limits as constraints on new physics poses a tremendous theoretical challenge.The most widely discussed mechanism for 0νββ is that of a light Majorana neutrino, which can propagate a long distance within a nucleus. However, if the mechanism involves a heavy scale, Λ ββ , the resulting L-violating process can be short-ranged. While naïvely short-range operators are suppressed compared to long-range interactions due to the heavy mediator propagator, in the case of 0νββ, the long-range interaction requires a helicity flip and is proportional to the mass of the light neutrino. In a standard seesaw scenario [17][18][19][20][21], this light neutrino mass is similarly suppressed by the same large mass scale, so the relative importance of long-versus short-range contributions is dependent upon the particle physics model under consideration and in general cannot be determined until the nuclear matrix elements for both types of processes are computed.Both long-and short-range mechanisms present substantial theoretical challenges if we hope to connect high energy physics with experimentally observed decay rates. The former case is difficult because one must understand long-distance nuclear correlations. In the latter case the short-distance physics is masked by QCD effects, requiring non-perturbative methods to match few-nucleon matrix elements to Standard Model operators.Effective field theory (EFT) arguments show that at leading order (LO) in the Standard Model, there are nine local four-...

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Heavy Physics Contributions to Neutrinoless Double Beta Decay from QCD

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“…We convert half-life limits into limits on masses and couplings, using the equations discussed in the previous section. We take into account the QCD corrections to the Wilson coefficients, calculated recently in [45]. In particular for the model with the singly charged scalar QCD corrections have been found to be very important numerically.…”

Section: Jhep12(2016)130 3 Numerical Resultsmentioning

confidence: 99%

Scalar-mediated double beta decay and LHC

Gonzalez

Helo

Hirsch

et al. 2016

J. High Energ. Phys.

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The decay rate of neutrinoless double beta (0νββ) decay could be dominated by Lepton Number Violating (LNV) short-range diagrams involving only heavy scalar intermediate particles, known as "topology-II" diagrams. Examples are diagrams with diquarks, leptoquarks or charged scalars. Here, we compare the LNV discovery potentials of the LHC and 0νββ-decay experiments, resorting to three example models, which cover the range of the optimistic-pessimistic cases for 0νββ decay. We use the LHC constraints from dijet as well as leptoquark searches and find that already with 20/fb the LHC will test interesting parts of the parameter space of these models, not excluded by the current limits on 0νββ-decay.

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“…We mention also [33], quoting M B = 0.95 GeV, and [28], which give M B = 2.15 GeV. Below we revisit the QCD corrections to the SRM and LRM of 0νββ-decay [13,14] applying Eq. (2) in order to extrapolate the pQCD results towards µ ∼ 100 MeV, the characteristic scale of 0νββ-decay.…”

Section: Qcd Running Coupling Constant In the Infrared Limitmentioning

confidence: 99%

“…Here we apply the IR extrapolation based on "freezing", discussed above, to the pQCD results for 0νββdecay derived in refs [13,14,35].…”

Section: Qcd Running Of Wilson Coefficientsmentioning

confidence: 99%

Neutrinoless double beta decay and QCD running at low energy scales

2018

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There is a common belief that the main uncertainties in the theoretical analysis of neutrinoless double beta (0νββ) decay originate from the nuclear matrix elements. Here, we uncover another previously overlooked source of potentially large uncertainties stemming from nonperturbative QCD effects. Recently perturbative QCD corrections have been calculated for all dimension 6 and 9 effective operators describing 0νββ-decay and their importance for a reliable treatment of 0νββ-decay has been demonstrated. However, these perturbative results are valid at energy scales above ∼1 GeV, while the typical 0νββ scale is about ∼100 MeV. In view of this fact we examine the possibility of extrapolating the perturbative results towards sub-GeV nonperturbative scales on the basis of the QCD coupling constant "freezing" behavior using background perturbation theory. Our analysis suggests that such an infrared extrapolation does modify the perturbative results for both short-range and long-range mechanisms of 0νββ-decay in general only moderately. We also discuss that the tensor ⊗ tensor effective operator cannot appear alone in the low energy limit of any renormalizable high-scale model and then demonstrate that all five linearly independent combinations of the scalar and tensor operators, which can appear in renormalizable models, are infrared stable.

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QCD running in neutrinoless double beta decay: Short-range mechanisms

Cited by 29 publications

References 31 publications

Heavy Physics Contributions to Neutrinoless Double Beta Decay from QCD

Heavy Physics Contributions to Neutrinoless Double Beta Decay from QCD

Scalar-mediated double beta decay and LHC

Neutrinoless double beta decay and QCD running at low energy scales

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