Resonant slepton production at the LHC in models with an ultralight gravitino

We examine resonant slepton production at the LHC with gravitinos in the final state. The slepton undergoes gauge decay into a neutralino and a lepton, the neutralino decays into a photon and a gravitino. By measuring the transverse masses of the gamma- G and the l-gamma- G subsystems it is possible to accurately reconstruct both the slepton and neutralino masses. In some regions of parameter space the slepton decays directly into a lepton and gravitino, giving an identical experimental topology to W production (l missing E_T). We present the novel matrix element squared for lepton-gravitino production. A peak in the tail of the lepton-missing momentum transverse mass distribution of the W provides a signature for the process and an accurate measurement of the slepton mass. We display the search reach for the LHC and 300 fb^{-1} of integrated luminosity.Comment: 13 pages. Minor changes in v

Z boson decay to photon plus Kaluza-Klein graviton in large extra dimensions

In the large extra dimensional ADD scenario, Z bosons undergo a one-loop decay into a photon and Kaluza-Klein towers of gravitons/gravi-scalars. We calculate such a decay width, extending previous arguments about the general form of the four-dimensional on-shell amplitude. The amplitudes calculated are relevant to processes in other extra dimensional models where the Standard Model fields are confined to a 4-brane.Comment: 47 pages, uses feynmp for diagrams. v2: typographical corrections for letter-sized paper and to correct feynmf parsing error. v3: minor error in polarisation averaging and reference corrected. v4: reflects changes for published version; arithmetic error corrected and reference updated; section on transversality conditions not present in published version retaine

Investigating the Supersymmetric Explanation of Anomalous CDF lepton(s) photon(s) Missing-E_T Events

The recent excess over the Standard Model prediction in the \mu \gamma missing-E_T channel reported by CDF can be well-explained by resonant smuon production with a single dominant R-parity violating coupling \lambda'_{211}, in the context of models where the gravitino is the lightest supersymmetric particle. The slepton decays to the lightest neutralino and a muon followed by neutralino decaying to a gravitino and photon. The kinematical distributions are fitted well by our hypothesis and we use them to constrain the available parameter space. The model also provides an explanation for the ee\gamma\gamma missing-E_T event observed in Run I of the Tevatron by the CDF experiment. Our model predicts an excess of between 5 and 35 events in a \gamma missing-E_T channel at Run I. We provide predictions for signatures expected by the model at Run II.Comment: 23 pages, Latex file + 10 figures and 4 Tables (included) Includes JHEP3.cls and axodraw.st

R-Parity Violating Supersymmetry Explanation for Large t tbar Forward-Backward Asymmetry

We propose a supersymmetric explanation for the anomalously high forward backward asymmetry in top pair production measured by CDF and D0. We suppose that it is due to the t-channel exchange of a right-handed sbottom which couples to d_R and t_R, as is present in the R-parity violating minimal supersymmetric standard model. We show that all Tevatron and LHC experiments' t tbar constraints may be respected for a sbottom mass between 300 and 1200 GeV, and a large Yukawa coupling >2.2, yielding A_{FB} up to 0.18. The non Standard Model contribution to the LHC charge asymmetry parameter is Delta A_C^y=0.017-0.045, small enough to be consistent with current measurements but non-zero and positive, allowing for LHC confirmation in the future within 20 fb^-1. A small additional contribution to the LHC t tbar production cross-section is also predicted, allowing a further test. We estimate that 10 fb^-1 of LHC luminosity would be sufficient to rule out the proposal to 95% confidence level, if the measurements of the t tbar cross-section turn out to be centred on the Standard Model prediction.Comment: 5 pages, 2 figures, v2 has added comments and references and increased statistics, leading to more accurate numerical predictions. v3 has typos in Fig 1 fixed: arrow directions and t and tbar labels. v4 has added discussion and corrections to Eq 4. v5 has luminosity predictions, additional checks and small numerical change

A New SUSY mass reconstruction method at the CERN LHC

We propose a new mass reconstruction technique for SUSY processes at the LHC. The idea is to completely solve the kinematics of the SUSY cascade decay by using the assumption that the selected events satisfy the same mass shell conditions of the sparticles involved in the cascade decay. Using this technique, we study the measurement of the mass of the bottom squarks in the cascade decay of the gluino. Based on the final state including two high p_T leptons and two b-jets, we investigate different possible approaches to the mass reconstruction of the gluino and the two bottom squarks. In particular we evaluate the performance of different algorithms in discriminating two bottom squark states with a mass difference as low as 5%.Comment: Revtex 16 pages, 8 figure

The R-Parity Violating Minimal Supergravity Model

We present the minimal supersymmetric standard model with general broken R-parity, focusing on minimal supergravity (mSUGRA). We discuss the origins of lepton number violation in supersymmetry. We have computed the full set of coupled one-loop renormalization group equations for the gauge couplings, the superpotential parameters and for all the soft supersymmetry breaking parameters. We provide analytic formule for the scalar potential minimization conditions which may be iterated to arbitrary precision. We compute the low-energy spectrum of the superparticles and the neutrinos as a function of the small set of parameters at the unification scale in the general basis. Specializing to mSUGRA, we use the neutrino masses to set new bounds on the R-parity violating couplings. These bounds are up-to five orders of magnitude stricter than the previously existing ones. In addition, new bounds on the R-parity violating couplings are also derived demanding a non-tachyonic sneutrino spectrum. We investigate the nature of the lightest supersymmetric particle and find extensive regions in parameter space, where it is not the neutralino. This leads to a novel set of supersymmetric signatures, which we classify.Comment: 42 pages, revtex4, 8 figures. Revised version corrects a factor of 2 in Eq. (86) with associated numerical corrections to Tables III,IV and Fig. I. Conclusions left unchange

SuSeFLAV: A program for calculating supersymmetric spectra and lepton flavor violation

We introduce the program SuSeFLAV for computing supersymmetric mass spectra with flavor violation in various supersymmetric breaking scenarios with/without seesaw mechanism. A short user guide summarizing the compilation, executables and the input files is provided.Comment: 3 pages, latex, pramana style, proceedings for Lepton Photon 201

ATLAS diboson excess could be an R -parity violating dismuon excess

We propose a new possible explanation of the ATLAS di-boson excess: that it is due to heavy resonant slepton production, followed by decay into di-smuons. The smuon has a mass not too far from the W and Z masses, and so it is easily confused with W or Z bosons after its subsequent decay into di-jets, through a supersymmetry violating and R-parity violating interaction. Such a scenario is not currently excluded by other constraints and remains to be definitively tested in Run II of the LHC. Such light smuons can easily simultaneously explain the discrepancy between the measurement of the anomalous magnetic moment of the muon and the Standard Model prediction.This work of B.C.A. has been partially supported by STFC grant ST/L000385/1. The work of P.S.B.D. is supported in part by a TUM University Foundation Fellowship and the DFG cluster of excellence “Origin and Structure of the Universe”.This is the author accepted manuscript. The final version is available from the American Physical Society via http://dx.doi.org/10.1103/PhysRevD.93.03501

R -parity violation in a warped GUT scale Randall-Sundrum framework

© 2016 American Physical Society. We consider a modified Randall-Sundrum (RS) framework between the Planck scale and the grand unified theory (GUT) scale. In this scenario, RS works as a theory of flavor and not as a solution to the hierarchy problem. The latter is resolved by supersymmetrizing the bulk, so that the minimal supersymmetric standard model is the effective four-dimensional theory. Matter fields are localized in the bulk in order to fit fermion-mass and mixing data. If R-parity violating (Rp) terms are allowed in the superpotential, their orders of magnitude throughout flavor space are then predicted, resulting in rich flavor textures. If the Rp contributions to neutrino masses are somewhat suppressed, then lepton-number violating models exist which explain the neutrino oscillation data while not being in contradiction with current experimental bounds. Another promising model is one where baryon number is violated and Dirac neutrino masses result solely from fermion localization. We sketch the likely discovery signatures of the baryon-number and the lepton-number violating cases.This work was partially supported by STFC grant ST/L000385/1. BCA was adjunct faculty in DTP TIFR during December 2014 and would like to thank the department for the hospitality extended during the early stages of this work and the Cambridge SUSY Working Group for helpful suggestions. BCA, AI and KS would like to thank Sudhir Vempati for the motivation and useful discussions. AI and KS also thank the organisers at WHEPP 2013 for the hospitality where the idea was conceived. AI and KS would also like to thank the CERN theory division for hospitality where part of the work was completed. AI would like to thank Tuhin Roy for discussions on contribution to renormalization of soft masses due to hidden sector effects

Requirements on collider data to match the precision of WMAP on supersymmetric dark matter

If future colliders discover supersymmetric particles and probe their properties, one could predict the dark matter density of the Universe and would constrain cosmology with the help of precision data provided by WMAP and PLANCK. We investigate how well the relic density can be predicted in minimal supergravity (mSUGRA), with and without the assumption of mSUGRA when analysing data. We determine the parameters to which the relic density is most sensitive, and quantify the collider accuracy needed. Theoretical errors in the prediction are investigated in some detail.Comment: 42 pages, 16 figures. v2 incorporates referee's comments: minor corrections/clarifications with additional figures to show regions of m12-m0 plane considere