RPV SUSY with Same-Sign Dileptons at LHC-14

We estimate the sensitivity of the 14 TeV LHC run to an R-parity violating supersymmetric model, via the same-sign dilepton (SSDL) signature. We consider the simplified model with light gluinos and stops, motivated by naturalness. We find that gluinos up to 1.4 TeV can be discovered with an integrated luminosity of 300 fb-1. If a high-luminosity option is implemented and a 3000 fb-1 dataset becomes available, the gluino mass reach can be increased to 1.6-1.75 TeV.Comment: 4 pages, 1 figure. Contributed to Snowmass Community Summer Study 2013. v2: references adde

The Same-Sign Dilepton Signature of RPV/MFV SUSY

The lack of observation of superpartners at the Large Hadron Collider so far has led to a renewed interest in supersymmetric models with R-parity violation (RPV). In particular, imposing the Minimal Flavor Violation (MFV) hypothesis on a general RPV model leads to a realistic and predictive framework. Naturalness suggests that stops and gluinos should appear at or below the TeV mass scale. We consider a simplified model with these two particles and MFV couplings. The model predicts a significant rate of events with same-sign dileptons and b-jets. We re-analyze a recent CMS search in this channel and show that the current lower bound on the gluino mass is about 800 GeV at 95% confidence level, with only a weak dependence on the stop mass as long as the gluino can decay to an on-shell top-stop pair. We also discuss how this search can be further optimized for the RPV/MFV scenario, using the fact that MFV stop decays often result in jets with large invariant mass. With the proposed improvements, we estimate that gluino masses of up to about 1.4 TeV can be probed at the 14 TeV LHC with a 100 fb^-1 data set.Comment: 18 pages, 6 figures; v2: References adde

Potential model calculations and predictions for csˉ\bm c\bar{\bm s} quarkonia

We investigate the spectroscopy and decays of the charm-strange quarkonium system in a potential model consisting of a relativistic kinetic energy term, a linear confining term including its scalar and vector relativistic corrections and the complete perturbative one-loop quantum chromodynamic short distance potential. The masses and wave functions of the various states are obtained using a variational technique, which are then used in a perturbative treatment of the potential to find the mass spectrum of the $c\bar{s}$ system and radiative decay widths. Our results compare well with the available data for the spectrum of $D_s$ states. We include a discussion of the effect of mixing and an investigation of the Lorentz nature of the confining potential.Comment: 6 pages 3 Table

Calcineurin Interacts with PERK and Dephosphorylates Calnexin to Relieve ER Stress in Mammals and Frogs

Background: The accumulation of misfolded proteins within the endoplasmic reticulum (ER) triggers a cellular process known as the Unfolded Protein Response (UPR). One of the earliest responses is the attenuation of protein translation. Little is known about the role that Ca 2+ mobilization plays in the early UPR. Work from our group has shown that cytosolic phosphorylation of calnexin (CLNX) controls Ca 2+ uptake into the ER via the sarco-endoplasmic reticulum Ca 2+-ATPase (SERCA) 2b. Methodology/Principal Findings: Here, we demonstrate that calcineurin (CN), a Ca 2+ dependent phosphatase, associates with the (PKR)-like ER kinase (PERK), and promotes PERK auto-phosphorylation. This association, in turn, increases the phosphorylation level of eukaryotic initiation factor-2 a (eIF2-a) and attenuates protein translation. Data supporting these conclusions were obtained from co-immunoprecipitations, pull-down assays, in-vitro kinase assays, siRNA treatments and [ 35 S]-methionine incorporation measurements. The interaction of CN with PERK was facilitated at elevated cytosolic Ca 2+ concentrations and involved the cytosolic domain of PERK. CN levels were rapidly increased by ER stressors, which could be blocked by siRNA treatments for CN-Aa in cultured astrocytes. Downregulation of CN blocked subsequent ER-stress-induced increases in phosphorylated elF2-a. CN knockdown in Xenopus oocytes predisposed them to induction of apoptosis. We also found that CLNX was dephosphorylated by CN when Ca 2+ increased. These data were obtained from [c 32 P]-CLN

New Tools In The Search For Supersymmetry

The Large Hadron Collider has thrust humanity into the TeV-scale era of particle physics, and with it we have discovered a new Higgs-like particle and set stronger limits on possible theories of supersymmetry and beyond-the-Standard-Model physics. But while the experimental community continues to improve their searches for new physics, the lack of clear beyond-the-Standard-Model discoveries so far has made it apparent that if we are to discover new physics there, the theoretical community must continually develop new methods as well. New tools must be forged and applied to the problems we face at the Large Hadron Collider and possible future particle colliders. This dissertation expresses one contribution, out of many, in this regard. We begin by using boosted top tagging to look for signals of R-parity conserving supersymmetry. Then we use other jet substructure techniques to look for signals of Rparity violating supersymmetry. Lastly, we use the SUSY-Yukawa sum rule to look beyond the phenomenology and probe the crucial cancellation of divergences at the heart of supersymmetric theories

Potential Model Calculations and Predictions for c¯s quarkonia

We investigate the spectroscopy and decays of the charm-strange quarkonium system in a potential model consisting of a relativistic kinetic energy term, a linear confining term including its scalar and vector relativistic corrections, and the complete perturbative one-loop quantum chromodynamic short distance potential. The unperturbed wave functions of the various states are obtained using a variational technique. These are then used in a perturbative treatment of the potential to fit the mass spectrum of the cs system and calculate the radiative decay widths. Our results compare well with the available data for the spectrum of Ds states. We include a discussion of the effect of mixing and investigation of the Lorentz nature of the confining potential