arXiv subjects

Gauthier Durieux

Publications and source records attributed to Gauthier Durieux.

40 records · Page 3Linked to original sources

arXiv2013

The same-sign top probe for baryon number violation at the LHC

Despite strong experimental evidences for their conservation at low energies, the baryon $B$ and lepton $L$ numbers are not expected to be absolute symmetries. Already violated in the Standard Model (SM) by non-perturbative effects (tiny at low temperatures and energies) and not justified by any fundamental principle, $B$ and $L$ appear naturally violated in beyond the Standard Model (BSM) scenarios, e.g. in supersymmetry (SUSY). The fact that any violation remained unobserved at low energies can nonetheless be explained, without pushing the associated characteristic sale beyond the TeV, by using SM flavour symmetries implemented BSM thanks to the Minimal Flavour Violation (MFV) prescription. Violation effects could therefore be observable at the LHC. Same-sign (anti-)tops, sometimes leading to a distinctive predominance of negatively charged lepton pairs over positively charged ones, is a clean signature that is for instance generically present in R-parity violating supersymmetry.

hep-ph↗

arXiv2013

The same-sign top signature of R-parity violation

Baryonic R-parity violation could explain why low-scale supersymmetry has not yet been discovered at colliders: sparticles would be hidden in the intense hadronic activity. However, if the known flavor structures are any guide, the largest baryon number violating couplings are those involving the top/stop, so a copious production of same-sign top-quark pairs is in principle possible. Such a signal, with its low irreducible background and efficient identification through same-sign dileptons, provides us with tell-tale signs of baryon number violating supersymmetry. Interestingly, this statement is mostly independent of the details of the supersymmetric mass spectrum. So, in this paper, after analyzing the sparticle decay chains and lifetimes, we formulate a simplified benchmark strategy that covers most supersymmetric scenarios. We then use this information to interpret the same-sign dilepton searches of CMS, draw approximate bounds on the gluino and squark masses, and extrapolate the reach of the future 14 TeV runs.

hep-ph↗

arXiv2013

Flavourful baryon and lepton number violation at the LHC

We observe that the flavour symmetries of the Standard Model gauge sector, broken as they are in the Standard Model Yukawa Lagrangian, naturally suppress baryon and lepton number violation at low energies and, simultaneously, make it accessible at the LHC through resonant processes involving at least six fermions from all three generations. We establish a model independent classification of such transitions and identify two classes that give rise to particularly clean LHC signatures, namely $\bar t μ^+ e^+$ and $\bar t \bar t$ + jets.

hep-ph↗

arXiv2013

Three-generation baryon and lepton number violation at the LHC

One of the most puzzling questions in particle physics concerns the status of the baryon (B) and lepton (L) quantum numbers. On the theoretical side, most new physics scenarios naturally lead to their non-conservation and some amount of violation is actually needed to explain the baryon asymmetry of the Universe. On the experimental side, low-energy constraints such as those on proton decay are so stringent that it is generally believed that no B and L violation will ever be seen in laboratories. We observe that this apparent contradiction, however, disappears when the flavor symmetries involving all three generations are taken into account. We then identify model-independent classes of B and/or L violating six-fermion-based processes that indeed simultaneously satisfy low-energy constraints and produce clearly identifiable signals at the LHC. Finally, through simplified models, we study two classes characterized by (ΔB;ΔL) = (\pm 1;\pm 3) and (\pm 2; 0), that lead to particularly striking signatures (t μ^+ e^+ and \bar t \bar t + jets, respectively).

hep-ph↗