Renormalization group-induced phenomena of top pairs from four-quark effective operators

We study the renormalization group(RG) evolution of four-quark operators that contribute to the top pair production. In particular, we focus on the cases in which certain observables are first induced from the one-loop RG while being absent at tree-level. From the operator mixing pattern, we classify all such RG-induced phenomena and underlying models that can induce them. We then calculate the full one-loop QCD RG evolution as the leading estimator of the effects and address the question of which RG-induced phenomena have largest and observable effects. The answer is related to the color structure of QCD. The studied topics include the RG-induction of top asymmetries, polarizations and polarization mixings as well as issues arising at this order. The RG-induction of top asymmetries is further compared with the generation of asymmetries from QCD and QED at one-loop order. We finally discuss the validity of using the RG as the proxy of one-loop effects on the top pair production. As an aside, we clarify the often-studied relations between top pair observables

Search for a doubly-charged boson in four-lepton final states in type II seesaw

CMS and ATLAS have searched for a doubly-charged boson <math altimg="si1.gif" xmlns="http://www.w3.org/1998/Math/MathML"><msup><mrow><mi>H</mi></mrow><mrow><mo>±</mo><mo>±</mo></mrow></msup></math> which may arise from type II seesaw in the 7 TeV run at the LHC by considering pair or associated production of doubly-charged bosons under the assumption of degenerate triplet scalars. In this work, we consider non-degenerate triplet components with the mass gap <math altimg="si2.gif" xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="normal">Δ</mi><mi>M</mi><mo>∼</mo><mn>1</mn><mtext>–</mtext><mn>40</mn><mtext> GeV</mtext></math> which leads to enhanced pair-production cross-sections of <math altimg="si1.gif" xmlns="http://www.w3.org/1998/Math/MathML"><msup><mrow><mi>H</mi></mrow><mrow><mo>±</mo><mo>±</mo></mrow></msup></math> added by the gauge decays of the heavier neutral and singly-charged bosons. We reevaluate the constraints in the Δ M – <math altimg="si3.gif" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>M</mi></mrow><mrow><msup><mrow><mi>H</mi></mrow><mrow><mo>+</mo><mo>+</mo></mrow></msup></mrow></msub></math> plane depending on the triplet vacuum expectation value <math altimg="si4.gif" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>v</mi></mrow><mrow><mi mathvariant="normal">Δ</mi></mrow></msub></math> in the type II seesaw model which are much more stringent than the current search limits. We further study the possibility of observing same-sign tetra-lepton signals in the allowed parameter space which can be probed in the future runs of the LHC

Can we reach the Zeptouniverse with rare K and B s,d decays?

The Large Hadron Collider (LHC) will directly probe distance scales as short as 10 −19 m, corresponding to energy scales at the level of a few TeV. In order to reach even higher resolutions before the advent of future high-energy colliders, it is necessary to consider indirect probes of New Physics (NP), a prime example being Δ F = 2 neutral meson mixing processes, which are sensitive to much shorter distance scales. However Δ F = 2 processes alone cannot tell us much about the structure of NP beyond the LHC scales. To identify for instance the presence of new quark flavour-changing dynamics of a left-handed (LH) or right-handed (RH) nature, complementary results from Δ F = 1 rare decay processes are vital. We therefore address the important question of whether NP could be seen up to energy scales as high as 200 TeV, corresponding to distances as small as O 1 0 − 21 m $$\mathcal{O}\left(1{0}^{-21}\right)\mathrm{m}$$ — the Zeptouniverse — in rare K and B s,d decays, subject to present Δ F = 2 constraints and perturbativity. We focus in particular on a heavy Z ′ gauge boson. If restricted to purely LH or RH Z ′ couplings to quarks, we find that rare K decays, in particular K + → π + ν ν ¯ $${K}^{+}\to {\pi}^{+}\nu \overline{\nu}$$ and K L → π 0 ν ν ¯ $${K}_L\to {\pi}^0\nu \overline{\nu}$$ , allow us to probe the Zeptouniverse. On the other hand rare B s and B d decays, which receive stronger Δ F = 2 constraints, allow us to reach about 15 TeV. Allowing for both LH and RH couplings a loosening of the Δ F = 2 constraints is possible, and we find that the maximal values of M Z ′ at which NP effects could be found that are consistent with perturbative couplings are approximately 2000 TeV for K decays and 160 TeV for rare B s,d decays. Because Z ′ exchanges in the B s,d → μ + μ − rare decays are helicity suppressed, we also consider tree-level scalar exchanges for these decays, for which we find that scales close to 1000 TeV can be probed for the analogous pure and combined LH and RH scenarios. We further present a simple idea for an indirect determination of M Z ′ that could be realised at the next linear e + e − or μ + μ − collider and with future precise flavour data

Abelianization of BPS quivers and the refined Higgs index

We count Higgs “phase” BPS states of general non-Abelian quiver, possibly with loops, by mapping the problem to its Abelian, or toric, counterpart and imposing Weyl invariance later. Precise Higgs index computation is particularly important for quivers with superpotentials; the Coulomb “phase” index is recently shown to miss important BPS states, dubbed intrinsic Higgs states or quiver invariants. We demonstrate how the refined Higgs index is naturally decomposed to a sum over partitions of the charge. We conjecture, and show in simple cases, that this decomposition expresses the Higgs index as a sum over a set of partition-induced Abelian quivers of the same total charge but generically of smaller rank. Unlike the previous approach inspired by a similar decomposition of the Coulomb index, our formulae compute the quiver invariants directly, and thus offer a self-complete routine for counting BPS states

Quadratic α′ -corrections to heterotic double field theory

We investigate α′ -corrections of heterotic double field theory up to quadratic order in the language of supersymmetric O(D,D+dim⁡G) gauged double field theory. After introducing double-vielbein formalism with a parametrization which reproduces heterotic supergravity, we show that supersymmetry for heterotic double field theory up to leading order α′ -correction is obtained from supersymmetric gauged double field theory. We discuss the necessary modifications of the symmetries defined in supersymmetric gauged double field theory. Further, we construct supersymmetric completion at quadratic order in α′

The gravity dual of supersymmetric Rényi entropy

Supersymmetric Rényi entropies are defined for three-dimensional N $$\mathcal{N}$$ = 2 superconformal field theories on a branched covering of a three-sphere by using the localized partition functions. Under a conformal transformation, the branched covering is mapped to S 1 × H 2 , whose gravity dual is the charged topological AdS 4 black hole. The black hole can be embedded into four-dimensional N $$\mathcal{N}$$ = 2 gauged supergravity where the mass and charge are related so that it preserves half of the supersymmetries. We compute the supersymmetric Rényi entropies with and without a certain type of Wilson loop operators in the gravity theory. We find they agree with those of the dual field theories in the large- N limit

More is different: Reconciling eV sterile neutrinos with cosmological mass bounds

It is generally expected that adding light sterile species would increase the effective number of neutrinos, Neff . In this paper we discuss a scenario that Neff can actually decrease due to the neutrino oscillation effect if sterile neutrinos have self-interactions. We specifically focus on the eV mass range, as suggested by the neutrino anomalies. With large self-interactions, sterile neutrinos are not fully thermalized in the early Universe because of the suppressed effective mixing angle or matter effect. As the Universe cools down, flavor equilibrium between active and sterile species can be reached after big bang nucleosynthesis (BBN) epoch, but leading to a decrease of Neff . In such a scenario, we also show that the conflict with cosmological mass bounds on the additional sterile neutrinos can be relaxed further when more light species are introduced. To be consistent with the latest Planck results, at least 3 sterile species are needed

Double soft limits of cosmological correlations

Correlation functions of two long-wavelength modes with several short-wavelength modes are shown to be related to lower order correlation functions, using the background wave method, and independently, by exploiting symmetries of the wavefunction of the Universe. These soft identities follow from the non-linear extension of the adiabatic modes of Weinberg, and their generalization by Hinterbichler et al. The extension is shown to be unique. A few checks of the identities are presented

Upgrading sterile neutrino dark matter to FI m P using scale invariance

In this article we propose a class of extremely light feebly interacting massive particle, FI m Ps. They are combination of feebly interacting massive particle with scale invariance, by which DM stability, mass origin and relic density are inherently related. In the scale invariant version of the Standard Model (SM) with three right-handed neutrinos ( ν SISM), the lightest N1 realizes the FI m P scenario. In this example scalar singlets, which are intrinsic to the ν SISM, generate mass and relic density for this FI m P simultaneously. Moreover, they are badly needed for electroweak symmetry spontaneously breaking. Interestingly, a 7.1 keV N1 with correct relic density, which can explain the recent 3.55 keV X-ray line, lies in the bulk parameter space of our model

Asymptotic symmetries of Yang-Mills theory

Asymptotic symmetries at future null infinity ( ℐ $$\mathrm{\mathcal{I}}$$ + ) of Minkowski space for electrodynamics with massless charged fields, as well as nonabelian gauge theories with gauge group G , are considered at the semiclassical level. The possibility of charge/color flux through ℐ $$\mathrm{\mathcal{I}}$$ + suggests the symmetry group is infinite-dimensional. It is conjectured that the symmetries include a G Kac-Moody symmetry whose generators are “large” gauge transformations which approach locally holomorphic functions on the conformal two-sphere at ℐ $$\mathrm{\mathcal{I}}$$ + and are invariant under null translations. The Kac-Moody currents are constructed from the gauge field at the future boundary of ℐ $$\mathrm{\mathcal{I}}$$ + . The current Ward identities include Weinberg’s soft photon theorem and its colored extension