Multi-scalar signature of self-interacting dark matter in the NMSSM and beyond

This work studies the self-interacting dark matter (SIDM) scenario in the general NMSSM and beyond, where the dark matter is a Majorana fermion and the force mediator is a scalar boson. An improved analytical expression for the dark matter (DM) self-interacting cross section which takes into account the Born level effects is proposed. Due to the large couplings and light mediator in SIDM scenario, the DM/mediator will go through multiple branchings if they are produced with high energy. Based on the Monte Carlo simulation of the showers in the DM sector, we obtain the multiplicities and the spectra of the DM/mediator from the Higgsino production and decay at the LHC for our benchmark points.

Curing the unphysical behaviour of NLO quarkonium production at the LHC and its relevance to constrain the gluon PDF at low scales

We address the unphysical energy dependence of quarkonium-hadroproduction cross sections at Next-to-Leading Order (NLO) in $$\alpha _s$$ α s which we attribute to an over-subtraction in the factorisation of the collinear singularities inside the PDFs in the $$\overline{\text {MS}}$$ MS ¯ scheme. Such over- or under-subtractions have a limited phenomenological relevance in most of the scattering processes in particle physics. On the contrary, it is particularly harmful for $$P_T$$ P T -integrated charmonium hadroproduction which renders a wide class of NLO results essentially unusable. Indeed, in such processes, $$\alpha _s$$ α s is not so small, the PDFs are not evolved much and can be rather flat for the corresponding momentum fractions and, finally, some process-dependent NLO pieces are either too small or too large. We propose a scale-fixing criterion which avoids such an over-subtraction. We demonstrate its efficiency for $$\eta _{c,b}$$ η c , b but also for a fictitious light elementary scalar boson. Having provided stable NLO predictions for $$\eta _{c,b}$$ η c , b $$P_T$$ P T -integrated cross sections, $$\sigma ^{\mathrm{NLO}}_{\eta _Q}$$ σ η Q NLO , and discussed the options to study $$\eta _{b}$$ η b hadroproduction, we argue that their measurement at the LHC can help better determine the gluon PDF at low scales and tell whether the local minimum in conventional NLO gluon PDFs around $$x=0.001$$ x = 0.001 at scales below 2 GeV is physical or not.

Erratum to: Dark photon from light scalar boson decays at FASER

Figure 1. Expected number of the signal events of the dark photon after correcting the ϕ decay width. We have found a mistake in calculations of the expected number of the signal events shown in figure 2, 4 and 5 of our paper.

Explaining Atomki anomaly and muon g − 2 in U(1)X extended flavour violating two Higgs doublet model

We investigate a two Higgs doublet model with extra flavour depending U(1)X gauge symmetry where Z′ boson interactions can explain the Atomki anomaly by choosing appropriate charge assignment for the SM fermions. For parameter region explaining the Atomki anomaly we obtain light scalar boson with $$ \mathcal{O} $$ O (10) GeV mass, and we explore scalar sector to search for allowed parameter space. We then discuss anomalous magnetic dipole moment of muon and lepton flavour violating processes induced by Yukawa couplings of our model.

Search for $$Z'$$ pair production from scalar boson decay in minimal $$U(1)_{L_\mu - L_\tau }$$ model at the LHC

We consider a model with gauged $$L_\mu ^{} - L_\tau ^{}$$ L μ - L τ symmetry in which the symmetry is spontaneously broken by a scalar field. The decay of the scalar boson into two new gauge bosons is studied as a direct consequence of the spontaneous symmetry breaking. Then, a possibility of searches for the gauge and scalar bosons through such a decay at the LHC experiment is discussed. We consider the case that the mass range of the gauge boson is $${\mathcal {O}}(10)$$ O ( 10 ) GeV, which is motivated by anomalies reported by LHCb. We will show that the signal significance of the searches for the gauge boson and scalar boson reach to 3 and 5 for the scalar mixing 0.012 and 0.015, respectively.

Dark photon from light scalar boson decays at FASER

FASER is one of the promising experiments which search for long-lived particles beyond the Standard Model. In this paper, we focus on dark photon associating with an additional U(1) gauge symmetry, and also a scalar boson breaking this U(1) gauge symmetry. We study the sensitivity to the dark photon originated from U(1)-breaking scalar decays. We find that a sizable number of dark photon signatures can be expected in wider parameter space than previous studies.

Unitarily inequivalent vacua and long-range forces: Phenomenology with scalar boson mass-shift

We explore the impact of a sudden shift in the mass of a scalar boson field on long-range forces mediated by this field under the framework of unitarily inequivalent vacua. Since the search for new long-range forces is an active experimental area probing physics beyond the Standard Model, the consequence of a non-trivial vacuum state of a scalar boson on these experiments is elucidated. We show that while the mass shift affects the one-boson exchange potential, the Casimir force remains only dependent on the vacuum state.