264 citations · 1k across the 26 of their papers we have counts for
27 papers
Dirac, Majorana, and Weyl Spinors in Arbitrary Dimension and Signature
Jan Hajer
Fermionic field types in arbitrary signature are often inferred from complex Spin representations alone, which obscures distinctions associated with real structures, disconnected s…
Neutrino oscillation data and a pseudo-Dirac heavy neutral lepton
Jan Hajer
Symmetry-protected seesaw models can accommodate light-neutrino oscillation data while keeping heavy neutral leptons (HNLs) within collider reach. In these models, the smallness of…
Heavy neutrino-antineutrino oscillations at the FCC-ee
Stefan Antusch, Jan Hajer, Bruno M. S. Oliveira
We discuss the impact of heavy neutrino-antineutrino oscillations (NNOs) on heavy neutral lepton (HNL) searches at proposed electron-positron colliders such as the future circular…
Decoherence effects on lepton number violation from heavy neutrino-antineutrino oscillations
Stefan Antusch, Jan Hajer, Johannes Rosskopp
We study decoherence effects and phase corrections in heavy neutrino-antineutrino oscillations (NNOs), based on quantum field theory with external wave packets. Decoherence damps t…
Exploiting exotic LHC datasets for long-lived new particle searches
Hesham El Faham, Andrea Giammanco, Jan Hajer
Motivated by the expectation that new physics may manifest itself in the form of very heavy new particles, most of the operation time of the LHC is devoted to collisions at th…
Beyond lepton number violation at the HL-LHC: Resolving heavy neutrino-antineutrino oscillations
Stefan Antusch, Jan Hajer, Johannes Rosskopp
Collider testable low-scale seesaw models predict pseudo-Dirac heavy neutrinos, that can produce an oscillating pattern of lepton number conserving and lepton number violating even…
Report of the Topical Group on Physics Beyond the Standard Model at Energy Frontier for Snowmass 2021
Tulika Bose, Antonio Boveia, Caterina Doglioni +318
This is the Snowmass2021 Energy Frontier (EF) Beyond the Standard Model (BSM) report. It combines the EF topical group reports of EF08 (Model-specific explorations), EF09 (More gen…
Simulating lepton number violation induced by heavy neutrino-antineutrino oscillations at colliders
Stefan Antusch, Jan Hajer, Johannes Rosskopp
We study pseudo-Dirac pairs of two almost mass-degenerate sterile Majorana neutrinos which generate light neutrino masses via a low-scale seesaw mechanism. These pseudo-Dirac heavy…
Opportunities for new physics searches with heavy ions at colliders
David d'Enterria, Marco Drewes, Andrea Giammanco +15
Opportunities for searches for phenomena beyond the Standard Model (BSM) using heavy-ions beams at high energies are outlined. Different BSM searches proposed in the last years in…
Unleashing the full power of LHCb to probe Stealth New Physics
Martino Borsato, Xabier Cid Vidal, Yuhsin Tsai +38
In this paper, we describe the potential of the LHCb experiment to detect Stealth physics. This refers to dynamics beyond the Standard Model that would elude searches that focus on…
Portal Effective Theories: A framework for the model independent description of light hidden sector interactions
Chiara Arina, Jan Hajer, Philipp Klose
We present a framework for the construction of portal effective theories (PETs) that couple effective field theories of the Standard Model (SM) to light hidden messenger fields. Us…
HECATE: A long lived particle detector concept for the FCC-ee or CEPC
Marcin Chrzaszcz, Marco Drewes, Jan Hajer
The next generation of circular high energy collider is expected to be a lepton collider, FCC-ee at CERN or CEPC in China. However, the civil engineering concepts foresee to equip…
New Long Lived Particles Searches in Heavy Ion Collisions at the LHC
Marco Drewes, Andrea Giammanco, Jan Hajer +1
We show that heavy ion collisions at the LHC provide a promising environment to search for signatures with displaced vertices in well-motivated New Physics scenarios. Compared to p…
Searching for long-lived particles beyond the Standard Model at the Large Hadron Collider
Juliette Alimena, James Beacham, Martino Borsato +198
Particles beyond the Standard Model (SM) can generically have lifetimes that are long compared to SM particles at the weak scale. When produced at experiments such as the Large Had…
Heavy Neutrinos in displaced vertex searches at the LHC and HL-LHC
Marco Drewes, Jan Hajer
We study the sensitivity of displaced vertex searches for heavy neutrinos produced in W boson decays in the LHC detectors ATLAS, CMS and LHCb. We also propose a new search that use…
New physics searches with heavy-ion collisions at the LHC
Roderik Bruce, David d'Enterria, Albert de Roeck +18
This document summarises proposed searches for new physics accessible in the heavy-ion mode at the CERN Large Hadron Collider (LHC), both through hadronic and ultraperipheral …
Searching for New Long Lived Particles in Heavy Ion Collisions at the LHC
Marco Drewes, Andrea Giammanco, Jan Hajer +2
We show that heavy ion collisions at the LHC provide a promising environment to search for new long lived particles in well-motivated New Physics scenarios. One advantage lies in t…
Novelty Detection Meets Collider Physics
Jan Hajer, Ying-Ying Li, Tao Liu +1
Novelty detection is the machine learning task to recognize data, which belong to an unknown pattern. Complementary to supervised learning, it allows to analyze data model-independ…
Perspectives to find heavy neutrinos with NA62
Marco Drewes, Jan Hajer, Juraj Klaric +1
The sensitivity of beam dump experiments to heavy neutrinos depends on the relative size of their mixings with the lepton flavours in the Standard Model. We study the impact of pre…
NA62 sensitivity to heavy neutral leptons in the low scale seesaw model
Marco Drewes, Jan Hajer, Juraj Klaric +1
The sensitivity of beam dump experiments to heavy neutral leptons depends on the relative strength of their couplings to individual lepton flavours in the Standard Model. We study…
Testing Naturalness
Chuan-Ren Chen, Jan Hajer, Tao Liu +2
Solutions to the electroweak hierarchy problem typically introduce a new symmetry to stabilize the quadratic ultraviolet sensitivity in the self-energy of the Higgs boson. The new…
Heavy Higgs Bosons at Low : from the LHC to 100 TeV
Nathaniel Craig, Jan Hajer, Ying-Ying Li +2
We present strategies to search for heavy neutral Higgs bosons decaying to top quark pairs, as often occurs at low in type II two Higgs doublet models such as the Higgs se…
Heavy Higgs Bosons at 14 TeV and 100 TeV
Jan Hajer, Ying-Ying Li, Tao Liu +1
Searching for Higgs bosons beyond the Standard Model (BSM) is one of the most important missions for hadron colliders. As a landmark of BSM physics, the MSSM Higgs sector at the LH…
Long-lived higgsinos as probes of gravitino dark matter at the LHC
S. Bobrovskyi, J. Hajer, S. Rydbeck
We investigate the LHC sensitivity to supersymmetric models with light higgsinos, small R-parity breaking and gravitino dark matter. The limits on decaying gravitino dark matter fr…