arXiv subjects

Arsenii Titov

Publications and source records attributed to Arsenii Titov.

24 records · Page 2Linked to original sources

arXiv2020

One-loop running of dimension-six Higgs-neutrino operators and implications of a large neutrino dipole moment

We compute the one-loop running of the dimension-six CP-even Higgs operators in the Standard Model effective field theory involving the right-handed component of the would-be Dirac neutrinos. We discuss the implications of a large Dirac neutrino magnetic dipole moment. In particular, we demonstrate that a neutrino magnetic moment explaining the recent XENON1T excess induces Higgs and $Z$ invisible decays with branching ratios in the range $[10^{-18}, 10^{-12}]$. These numbers are unfortunately beyond the reach of current and near future facilities.

hep-ph↗

arXiv2020

Effective field theory for vector-like leptons and its collider signals

We argue that in models with several high scales; e.g. in composite Higgs models or in gauge extensions of the Standard Model (SM), vector-like leptons can be likely produced in a relatively large $\sqrt{s}$ region of the phase space. Likewise, they can easily decay into final states not containing SM gauge bosons. This contrasts with the topology in which these new particles are being searched for at the LHC. Adopting an effective field theory approach, we show that searches for excited leptons must be used instead to test this scenario. We derive bounds on all the relevant interactions of dimension six; the most constrained ones being of about $0.05$ TeV$^{-2}$. We build new observables to improve current analyses and study the impact on all single-field UV completions of the SM extended with a vector-like lepton that can be captured by the effective field theory at tree level, in the current and in the high-luminosity phase of the LHC.

hep-ph↗

arXiv2020

Testing Lepton Flavor Models at ESSnuSB

We review and investigate lepton flavor models, stemming from discrete non-Abelian flavor symmetries, described by one or two free model parameters. First, we confront eleven one- and seven two-parameter models with current results on leptonic mixing angles from global fits to neutrino oscillation data. We find that five of the one- and five of the two-parameter models survive the confrontation test at $3σ$. Second, we investigate how these ten one- and two-parameter lepton flavor models may be discriminated at the proposed ESSnuSB experiment in Sweden. We show that the three one-parameter models that predict $\sinδ_{\rm CP}=0$ can be distinguished from those two that predict $|\sinδ_{\rm CP}|=1$ by at least $7σ$. Finally, we find that three of the five one-parameter models can be excluded by at least $5σ$ and two of the one-parameter as well as at most two of the five two-parameter models can be excluded by at least $3σ$ with ESSnuSB if the true values of the leptonic mixing parameters remain close to the present best-fit values.

hep-ph↗

arXiv2020

One-loop matching in the SMEFT extended with a sterile neutrino

We study the phenomenology of the simplest renormalisable model that, at low energy, leads to the effective field theory of the Standard Model extended with right-handed neutrinos ($ν$SMEFT). Our aim is twofold. First, to contextualise new collider signatures in models with sterile neutrinos so far studied only using the bottom-up approach. And second and more important, to provide a thorough example of one-loop matching in the diagrammatic approach, of which other matching techniques and automatic tools can benefit for cross-checks. As byproducts of this work, we provide for the first time: (i) a complete off-shell basis for the $ν$SMEFT and explicit relations between operators linked by equations of motion; (ii) a complete basis for the low-energy effective field theory ($ν$LEFT) and the tree-level matching onto the $ν$SMEFT; (iii) partial one-loop anomalous dimensions in the $ν$LEFT. This way, our work comprises a new step forward towards the systematisation of one-loop computations in effective field theories, especially if the SM neutrinos are Dirac.

hep-ph↗

arXiv2019

Higgs phenomenology as a probe of sterile neutrinos

Physics beyond the Standard Model can manifest itself as both new light states and heavy degrees of freedom. In this paper, we assume that the former comprise only a sterile neutrino, $N$. Therefore, the most agnostic description of the new physics is given by an effective field theory built upon the Standard Model fields as well as $N$. We show that Higgs phenomenology provides a sensitive and potentially crucial tool to constrain effective gauge interactions of sterile neutrinos, not yet probed by current experiments. In parallel, this motivates a range of new Higgs decay channels with clean signatures as candidates for the next LHC runs, including $h\to γ+p_T^\text{miss}$ and $h\to γγ+p_T^\text{miss}$.

hep-ph↗

arXiv2019

Probes of the Standard Model effective field theory extended with a right-handed neutrino

If neutrinos are Dirac particles and, as suggested by the so far null LHC results, any new physics lies at energies well above the electroweak scale, the Standard Model effective field theory has to be extended with operators involving the right-handed neutrinos. In this paper, we study this effective field theory and set constraints on the different dimension-six interactions. To that aim, we use LHC searches for associated production of light (and tau) leptons with missing energy, monojet searches, as well as pion and tau decays. Our bounds are generally above the TeV for order one couplings. One particular exception is given by operators involving top quarks. These provide new signals in top decays not yet studied at colliders. Thus, we also design an LHC analysis to explore these signatures in the $t\overline{t}$ production. Our results are also valid if the right-handed neutrinos are Majorana and long-lived.

hep-ph↗