Publications

Order by: publication date number of citations

• Lepton flavour violation and neutrino masses

  Ana M. Teixeira

  SciPost Phys. Proc. 1, 015 (2019) · published 19 February 2019 | Toggle abstract · pdf

  Neutrino oscillations provided the first evidence for the violation of flavour in the lepton sector, and established a clear need to consider extensions of the Standard Model. Many new phenomena can emerge from these New Physics (NP) constructions, among which processes violating lepton number and charged lepton flavour, all clear signals of New Physics. Following a short overview of the status of experimental searches, we comment on the prospects of several models of massive neutrinos, from minimal constructions to complete NP models, to the above mentioned observables.

• Charged lepton flavour violating processes

  Adrian Signer

  SciPost Phys. Proc. 1, 014 (2019) · published 19 February 2019 | Toggle abstract · pdf

  Charged lepton flavour violating processes are naturally present in many extensions of the Standard Model. After a brief overview on the experimental situation, an effective-field-theory framework is described that allows to interpret and compare the various experiments in a consistent way. The usefulness of this approach is then illustrated in the context of a specific model with a doubly charged scalar.

• Point sources of ultra-high-energy neutrinos: Minimalist predictions for near-future discovery

  Damiano F. G. Fiorillo, Mauricio Bustamante, Victor B. Valera

  SciPost Phys. Proc. 13, 009 (2023) · published 28 September 2023 | Toggle abstract · pdf

  The discovery of ultra-high-energy neutrinos, with energies above 100 PeV, may soon be within reach of upcoming neutrino telescopes. We present a robust framework to compute the statistical significance of point-source discovery via the detection of neutrino multiplets. We apply it to the radio array component of IceCube-Gen2. To identify a source with $3\sigma$ significance, IceCube-Gen2 will need to detect a triplet, at best, and an octuplet, at worst, depending on whether the source is steady-state or transient, and on its position in the sky. The discovery, or absence, of sources significantly constrains the properties of the source population.

• Experimental status of LNU in B decays in LHCb

  Sean Benson on behalf of the LHCb collaboration

  SciPost Phys. Proc. 1, 011 (2019) · published 19 February 2019 | Toggle abstract · pdf

  In the Standard Model, the three charged leptons are identical copies of each other, apart from mass differences. Experimental tests of this feature in semileptonic decays of b-hadrons are highly sensitive to New Physics particles which preferentially couple to the 2nd and 3rd generations of leptons. A review of the latest lepton universality tests in semileptonic $b\to c$ transitions at LHCb is reported.

• Implications of tau data for CP violation in K decays

  Antonio Rodríguez-Sánchez

  SciPost Phys. Proc. 1, 005 (2019) · published 18 February 2019 | Toggle abstract · pdf

  The $D=6$ contribution of the Operator Product Expansion (OPE) of the VV-AA correlator of quark currents can be related to hadronic matrix elements associated to CP violation in non-leptonic kaon decays. We use those relations to find an updated value for $\langle(\pi\pi)_{I=2}|\mathcal{Q}_{8}|K\rangle$ in the chiral limit using the updated ALEPH spectral function. Taking instead values of the matrix elements from the lattice to obtain the $D=6$ vacuum elements provides a new short-distance constraint that allows for an inclusive determination of $f_{\pi}$ and an updated value for the $D=8$ condensate.

• Studying mass generation for gluons

  Gernot Eichmann, Jan M. Pawlowski

  SciPost Phys. Proc. 6, 018 (2022) · published 31 May 2022 | Toggle abstract · pdf

  In covariant gauges, the gluonic mass gap in Yang-Mills theory manifests itself in the basic observation that the massless pole in the perturbative gluon propagator disappears in nonperturbative calculations, but the origin of this behavior is not yet fully understood. We summarize a recent study of the respective dynamics with Dyson-Schwinger equations in Landau-gauge Yang-Mills theory. We identify the parameter that distinguishes the massive Yang-Mills regime from the massless decoupling solutions, whose endpoint is the scaling solution. Similar to the PT-BFM scheme, we find evidence that mass generation in the transverse sector is triggered by longitudinal massless poles.

• Excitations of static isolated fermions in the Higgs phase of gauge Higgs theory

  Kazue Matsuyama, Jeff Greensite

  SciPost Phys. Proc. 6, 012 (2022) · published 31 May 2022 | Toggle abstract · pdf

  A spectrum of localized excitations of isolated static fermions has been discovered in several different gauge Higgs theories. In lattice numerical simulations, we show that the charged elementary particles can have the spectrum of excitations in the Higgs phase of SU(3) gauge Higgs theory, q=2 Abelian Higgs theory, Landau-Ginzburg theory, and in chiral U(1) gauge Higgs theory. Possibly these excited states of the isolated fermions can be observed in ARPES studies of conventional superconductors. Also, we consider that similar kinds of excitations could exist in other gauge Higgs theories, such as the electroweak sector of the Standard Model.

• Background field method and generalized field redefinitions in effective field theories

  Andrea Quadri

  SciPost Phys. Proc. 7, 045 (2022) · published 22 June 2022 | Toggle abstract · pdf

  We study the non-linear background field redefinitions arising at the quantum level in a spontaneously broken effective gauge field theory. The non-linear field redefinitions are crucial for the symmetric (i.e. fulfilling all the relevant functional identities of the theory) renormalization of gauge-invariant operators. In a general $R_\xi$-gauge the classical background-quantum splitting is also non-linearly deformed by radiative corrections. In the Landau gauge these deformations vanish to all orders in the loop expansion.

• Lattice simulations of the QCD chiral transition at real $\mu_B$

  Attila Pasztor, Szabolcs Borsanyi, Zoltan Fodor, Matteo Giordano, Sandor D. Katz, Daniel Nogradi, Chik Him Wong

  SciPost Phys. Proc. 6, 002 (2022) · published 31 May 2022 | Toggle abstract · pdf

  Most lattice studies of hot and dense QCD matter rely on extrapolation from zero or imaginary chemical potentials. The ill-posedness of numerical analytic continuation puts severe limitations on the reliability of such methods. We studied the QCD chiral transition at finite real baryon density with the more direct sign reweighting approach. We simulate up to a baryochemical potential-temperature ratio of $\mu_B/T=2.7$, covering the RHIC Beam Energy Scan range, and penetrating the region where methods based on analytic continuation are unpredictive. This opens up a new window to study QCD matter at finite $\mu_B$ from first principles.

• Timelike transition form factor for CP-odd Higgs boson production

  Ken Sasaki, Tsuneo Uematsu

  SciPost Phys. Proc. 7, 044 (2022) · published 22 June 2022 | Toggle abstract · pdf

  We investigate the production of CP-odd Higgs boson $A^0$ associated with a real $\gamma$ in $e^+e^-$ collisions. Because of the properties of $A^0$ coupling to the other fields, the main contribution comes from the top-quark triangle loop diagrams. We obtain the timelike transition form factor which describes the production amplitude of $A^0$ in the $e^+e^-$ collisions. This timelike transition form factor is related to the spacelike transition form factor relevant for the $A^0$ production in $e^-\gamma$ collisions. It turns out that the possible extra contributions from chargino-sneutrino and neutralino-selectron box diagrams do not give sizable effects.