Search For Large Extra Dimensions Research Articles

Resummed inclusive cross-section in ADD model at N3LL

We present three loop soft-plus-virtual (SV) corrections to the spin-2 production at the Large Hadron Collider (LHC). For this calculation, we make use of the recently computed quark and gluon three loop form factors for the spin-2 production, the universal soft-collinear coefficients as well as the mass factorization kernels. The SV coefficients are presented up to next-to-next-to-next-to leading order (N3LOsv). We also use these coefficients at three loops to compute the resummed prediction for inclusive cross-section to next-to-next-to-next-to leading logarithmic accuracy (N3LL) matched to N3LOsv. We use the standard technique to derive the Mellin N-dependent coefficients and also the N-independent coefficients to achieve the resummation using the minimal prescription matching procedure. Considering the spin-2 propagator in the large extra dimensional (ADD) model, we also study the numerical impact of these three-loop SV corrections as well as the resummed predictions on the di-lepton invariant mass distribution at the 13 TeV LHC. We find that the conventional scale uncertainties in the N3LOsv +N3LL resummed results substantially get reduced to as low as 2% in the high invariant mass region. We also estimate the PDF uncertainties in our predictions that will be useful in the experimental searches for large extra dimensions.

Search for large extra dimensions in dimuon and dielectron events in pp collisions at [formula omitted

Results are presented from a search for large, extra spatial dimensions in events with either two isolated muons or two isolated electrons. The data are from proton–proton interactions at s=7 TeV collected with the CMS detector at the LHC. The size of the data sample corresponds to an integrated luminosity of approximately 2 fb−1. The observed dimuon and dielectron mass spectra are found to be consistent with standard-model expectations. Depending on the number of extra dimensions, the 95% confidence level limits from the combined μμ and ee channels range from Ms>2.4 TeV to Ms>3.8 TeV, where Ms characterizes the scale for the onset of quantum gravity.

Search for large extra dimensions in the diphoton final state at the Large Hadron Collider

A search for large extra spatial dimensions via virtual-graviton exchange in the diphoton channel has been carried out with the CMS detector at the LHC. No excess of events above the standard model expectations is found using a data sample collected in proton-proton collisions at \( \sqrt {s} = 7 \) TeV and corresponding to an integrated luminosity of 36 pb− 1. New lower limits on the effective Planck scale in the range of 1.6–2.3TeV at the 95% confidence level are set, providing the most restrictive bounds to date on models with more than two large extra dimensions.

Searching for physics beyond the Standard Model with High Energy Colliders

In this paper we review a selection of recent results obtained in the area of experimental searches for physics beyond the Standard Model performed at present high-energy physics colliders. In particular we illustrate searches for squarks and gluinos, searches for scalar top and scalar bottom in different scenarios, searches for large extra dimensions, and more in general signature based searches. As no evidence for new physics have been found so far, 95% Confidence Level limits have been set for all the theoretical scenarios that have been investigated by present high energy colliders.

Search for Large Extra Dimensions in Final States Containing One Photon or Jet and Large Missing Transverse Energy Produced inpp¯Collisions ats=1.96 TeV

We present the results of searches for large extra dimensions in samples of events with large missing transverse energy E_{T} and either a photon or a jet produced in pp[over ] collisions at sqrt[s]=1.96 TeV collected with the Collider Detector at Fermilab II. For gamma+E_{T} and jet+E_{T} candidate samples corresponding to 2.0 and 1.1 fb;{-1} of integrated luminosity, respectively, we observe good agreement with standard model expectations and obtain a combined lower limit on the fundamental parameter of the large extra dimensions model M_{D} as a function of the number of extra dimensions in the model.

Search for Large Extra Dimensions via Single Photon plus Missing Energy Final States ats=1.96 TeV

We report on a search for large extra dimensions in a data sample of approximately 1 fb(-1) of pp[over] collisions at sqrt s=1.96 TeV. We investigate Kaluza-Klein graviton production with a photon and missing transverse energy in the final state. At the 95% C.L. we set limits on the fundamental mass scale M(D) from 884 to 778 GeV for two to eight extra dimensions.

Search for large extra dimensions in the monojet+E(T) channel with the DØ detector.

We present a search for large extra dimensions (ED) in pp collisions at a center-of-mass energy of 1.8 TeV using data collected by the DØ detector at the Fermilab Tevatron in 1994-1996. Data corresponding to 78.8+/-3.9 pb(-1) are examined for events with large missing transverse energy, one high-p(T) jet, and no isolated muons. There is no excess observed beyond expectation from the standard model, and we place lower limits on the fundamental Planck scale of 1.0 and 0.6 TeV for 2 and 7 ED, respectively.

Brane worlds and the cosmic coincidence problem

Brane world models with ``large'' extra dimensions with radii in the ${r}_{l}\ensuremath{\sim}10--100\ensuremath{\mu}\mathrm{m}$ range and smaller ones at ${r}_{s}l~(1\mathrm{TeV}{)}^{\ensuremath{-}1}$ have the potential to solve the cosmic coincidence problem, i.e., the apparently fortuitous equality between dark matter and dark energy components today. The main ingredient is the assumption of a stabilization mechanism fixing the total volume of the compact submanifold, but allowing for shape deformations. The latter are associated with phenomenologically safe ultralight scalar fields. The bulk field Casimir energy naturally plays the role of dark energy, which decreases in time because of the expanding ${r}_{l}.$ Stable Kaluza-Klein states may play the role of dark matter with an increasing, ${O(1/r}_{s}),$ mass. The cosmological equations exhibit attractor solutions in which the global equation of state is negative, the ratio between dark energy and dark matter is constant, and the observed value of the ratio is obtained for two large extra dimensions. Experimental searches for large extra dimensions should take into account that, due to the strong coupling between dark matter and radii dynamics, the size of the large extra dimensions inside the galactic halo may be smaller than the average value.

The search for new phenomena at the Tevatron

Presented here are the latest results of searches for new physics phenomena, beyond the Standard Model, in the data collected by the D0 and CDF experiments at the Fermilab Tevatron. New results are presented on the search for large extra dimensions using the ∼100 pb −1 collected during Run I (1992–1996). Preliminary results on the Run II data from the search for first generation leptoquarks are also shown. The sensitivity of both searches with the full expected statistics of Run II is also discussed.