The new “MUON G-2” result and supersymmetry

The electroweak (EW) sector of the Minimal Supersymmetric Standard Model (MSSM), with the lightest neutralino as Dark Matter (DM) candidate, can account for a variety of experimental data. This includes the DM content of the universe, DM direct detection limits, EW SUSY searches at the LHC and in particular the so far persistent $$3-4\,\sigma $$ 3 - 4 σ discrepancy between the experimental result for the anomalous magnetic moment of the muon, $$(g-2)_\mu $$ ( g - 2 ) μ , and its Standard Model (SM) prediction. The recently published “MUON G-2” result is within $${0.8}\,\sigma $$ 0.8 σ in agreement with the older BNL result on $$(g-2)_\mu $$ ( g - 2 ) μ . The combination of the two results was given as $$a_\mu ^{\mathrm{exp}} = (11 659 {206.1}\pm {4.1}) \times 10^{-10}$$ a μ exp = ( 11659 206.1 ± 4.1 ) × 10 - 10 , yielding a new deviation from the SM prediction of $$\Delta a_\mu = ({25.1}\pm {5.9}) \times 10^{-10}$$ Δ a μ = ( 25.1 ± 5.9 ) × 10 - 10 , corresponding to $${4.2}\,\sigma $$ 4.2 σ . Using this improved bound we update the results presented in Chakraborti et al. (Eur Phys J C 80(10):984, 2020) and set new upper limits on the allowed parameters space of the EW sector of the MSSM. We find that with the new $$(g-2)_\mu $$ ( g - 2 ) μ result the upper limits on the (next-to-) lightest SUSY particle are in the same ballpark as previously, yielding updated upper limits on these masses of $$\sim 750 \,\, \mathrm {GeV}$$ ∼ 750 GeV . In this way, a clear target is confirmed for future (HL-)LHC EW searches, as well as for future high-energy $$e^+e^-$$ e + e - colliders, such as the ILC or CLIC.

Study of long-lived heavy charged particles produced in pp collisions at energy 13 TeV

We are interested in long-lived heavy charged particles because they would be possible SUSY particle candidats. This paper shows our preliminary results of long-lived heavy charged particles generation using PYTHIA 8. More than 107 events have been generated with pp collisions at energy in the center of mass = 13 TeV and about 3.27 105 long-lived heavy charged particles candidates have been found in the geometric acceptance of the LHCb detector. Long-lived heavy charged particles has mass 1.025 TeV/c2 and lifetime 157.7 nanoseconds, therefore they can travel throughout all subdetectors. We try not only calculate their acceptance in function of transverse momentum and rapidity but also combine a pair of candidats with opposite charge in order to reconstruct their invariant mass. In the next step, we have intention to identify stau using the informations from subdetectors such as the inner tracker and the muon chambers.

Searches for PromptR-Parity-Violating Supersymmetry at the LHC

Searches for supersymmetry (SUSY) at the LHC frequently assume the conservation ofR-parity in their design, optimization, and interpretation. In the case thatR-parity is not conserved, constraints on SUSY particle masses tend to be weakened with respect toR-parity-conserving models. We review the current status of searches forR-parity-violating (RPV) supersymmetry models at the ATLAS and CMS experiments, limited to 8 TeV search results published or submitted for publication as of the end of March 2015. All forms of renormalisable RPV terms leading to prompt signatures have been considered in the set of analyses under review. Discussing results for searches for promptR-parity-violating SUSY signatures summarizes the main constraints for various RPV models from LHC Run I and also defines the basis for promising signal regions to be optimized for Run II. In addition to identifying highly constrained regions from existing searches, also gaps in the coverage of the parameter space of RPV SUSY are outlined.

Supervariable approach to nilpotent symmetries of a couple of N = 2 supersymmetric quantum mechanical models

We derive the on-shell as well as off-shell nilpotent supersymmetric (SUSY) symmetry transformations for the [Formula: see text] = 2 SUSY quantum mechanical model of a (0 + 1)-dimensional (1D) free SUSY particle by exploiting the SUSY-invariant restrictions on the (anti-)chiral supervariables of the SUSY theory that is defined on a (1, 2)-dimensional supermanifold (parametrized by a bosonic variable t and a pair of Grassmannian variables θ and [Formula: see text] with [Formula: see text]). Within the framework of our novel approach, we express the Lagrangian and conserved SUSY charges in terms of the (anti-)chiral supervariables to demonstrate the SUSY invariance of the Lagrangian as well as the nilpotency of the SUSY conserved charges in a simple manner. Our approach has the potential to be generalized to the description of other [Formula: see text] = 2 SUSY quantum mechanical systems with physically interesting potential functions. To corroborate the preceding assertion, we apply our method to derive the [Formula: see text] = 2 continuous and nilpotent SUSY transformations for one of the simplest interacting SUSY systems of a 1D harmonic oscillator.

Universal mass limits on gluino and third-generation squarks in the context of Natural-like SUSY spectra

In this paper, we present results based on a combination of four inclusive topology searches for supersymmetry (SUSY) from the CMS experiment, and use this to determine universal mass limits on gluino and third-generation squarks in the context of Natural-like SUSY spectra. This class of sparticle spectra is inspired by the argument of naturalness, which originates from both consideration of fine-tuning arguments, and the need to satisfy current experimental search constraints. The class of Natural-like SUSY spectra considered follows the typical Natural SUSY model made up of a gluino, third-generation squarks, and higgsino sparticles, but is extended to more complex spectra containing sleptons. We show that the limits obtained from the combination of inclusive topology searches are far more stable than those from individual searches, with respect to the assumed underlying complexity of the spectra, and hence these limits can be considered as universal mass limits on gluino and third-generation squarks, defined in the context of this broad class of Natural-like SUSY spectra. Furthermore, we present our results using a simple colour scheme that allows a straightforward interpretation of any Natural-like SUSY spectrum with our limits. Complementing the final results of the 2011 searches based on 5 fb-1 of integrated luminosity, with the first published results from 2012 searches using approximately 11 fb-1, we find that gluinos with a mass of [Formula: see text] and third-generation top and bottom squarks with masses of [Formula: see text] are excluded for low masses of the lightest SUSY particle (LSP). These limits weaken to [Formula: see text] and [Formula: see text], when the mass of the LSP is increased to several hundred GeV. Based on this result, we establish a prediction of how these limits might evolve when the full 2012 dataset is analysed, with both the CMS and ATLAS experiments combined. This outlook suggests that for low masses of the LSP, gluinos with a mass of [Formula: see text] and third-generation squarks with masses of [Formula: see text] are likely to be excluded. For high LSP masses, these limits are expected to decrease to [Formula: see text] and [Formula: see text]. Therefore, despite the fact that the LHC already probes a significant region of the SUSY parameter space, Natural SUSY scenarios based on rather stringent fine-tuning requirements may not be fully excluded by the data taken so far. This suggests that additional data is needed, to be recorded during the higher energy running of the LHC expected in 2015. The importance of combining relevant inclusive topology searches, in order to make the most universal interpretations possible, is a general recommendation for future experimental searches at the LHC.

SOFT LEPTOGENESIS AND GRAVITINO DARK MATTER IN GAUGE MEDIATION

In gauge mediated SUSY breaking models, the gravitino is generally the lightest SUSY particle and can be a candidate for a dark matter. However the viable abundance of the gravitino requires rather low reheating temparature. With this low reheating temparature, it is difficult to explain the baryon asymmetry of the universe with thermal leptogenesis. We consider the extended scenario of the gauge mediation, which generates A-terms. In this extended scenario, soft leptogenesis works successfully with the low reheating temperature. Therefore we can explain the baryon asymmetry and gravitino dark matter simultaneously.

REVISITING THE MODIFIED STAROBINSKY MODEL WITH A COSMOLOGICAL CONSTANT

The Starobinsky model is a natural inflationary scenario in which inflation arises due to quantum effects of the massless matter fields. A modified version of the Starobinsky (MSt) model takes the masses of matter fields and the cosmological constant, Λ, into account. The equations of motion become much more complicated; however, approximate analytic and numeric solutions are possible. In the MSt model, inflation starts due to the supersymmetric (SUSY) particle content of the underlying theory, and the transition to the radiation-dominated epoch occurs due to the relatively heavy s-particles decoupling. For Λ = 0 the inflationary solution is stable until the last stage, just before decoupling. In the present paper we generalize this result for Λ ≠ 0, since Λ should be nonvanishing at the SUSY scale. We also take into account the radiative corrections to Λ. The main result is that the inflationary solution of the MSt model remains robust and stable.