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Title: Search for Randall-Sundrum Gravitons in 1.2 fb-1 of Run II High Mass Diphoton Data at CDF

Authors:
 [1]
  1. Liverpool U.
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1415818
Report Number(s):
FERMILAB-THESIS-2007-17
758670
DOE Contract Number:
AC02-07CH11359
Resource Type:
Thesis/Dissertation
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Wynne, Sara-Madge Violette. Search for Randall-Sundrum Gravitons in 1.2 fb-1 of Run II High Mass Diphoton Data at CDF. United States: N. p., 2007. Web. doi:10.2172/1415818.
Wynne, Sara-Madge Violette. Search for Randall-Sundrum Gravitons in 1.2 fb-1 of Run II High Mass Diphoton Data at CDF. United States. doi:10.2172/1415818.
Wynne, Sara-Madge Violette. Sun . "Search for Randall-Sundrum Gravitons in 1.2 fb-1 of Run II High Mass Diphoton Data at CDF". United States. doi:10.2172/1415818. https://www.osti.gov/servlets/purl/1415818.
@article{osti_1415818,
title = {Search for Randall-Sundrum Gravitons in 1.2 fb-1 of Run II High Mass Diphoton Data at CDF},
author = {Wynne, Sara-Madge Violette},
abstractNote = {},
doi = {10.2172/1415818},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Apr 01 00:00:00 EDT 2007},
month = {Sun Apr 01 00:00:00 EDT 2007}
}

Thesis/Dissertation:
Other availability
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  • The work presented in this thesis is the search for Randall-Sundrum (RS) gravitons from an analysis of approximately 1 fb -1 data collected with the D0 detector at Fermilab. The standard model has been a great success in explaining all experimental observations in particle physics. However, we also know that it has fundamental problems. One of these problems, called the hierarchy problem, is related to the large difference between the electroweak scale and the Planck scale. The model proposed by Randall and Sundrum presents a possible solution to the hierarchy problem by introducing physics beyond the standard model. Randall andmore » Sundrum's theory postulates the existence of a 4th spatial dimension in addition to the conventional (3+1)-dimensional space. Gravity is localized on a 3+1 dimensional subspace, called a brane (Planck brane) that is separated in this new 4th spatial dimension from the standard model brane. As one moves away from this Planck brane, gravity is exponentially suppressed and this explains why gravity appears so weak at the standard model brane. In the simplest RS model, the only particles that propagate in the extra dimension are gravitons. The graviton manifests itself on the standard model brane as a series of excited states that couple to standard model particles with similar strength as the electroweak interaction. The ground state is the massless graviton and the order of magnitude of the mass of the lowest excited state is expected to be one TeV. The first excited mode of the graviton might be produced resonantly at the Tevatron. Gravitons can decay into fermion-antifermion or diboson pairs. Here I search for gravitons through their decay to e +e - and γγ final states. These final states have similar signatures in our detector and can thus be treated together. After analyzing the data I do not find any excess over standard model expectations and set an upper limit on the production rate of such gravitons. I compare this limit to the production rate predicted by the theory for a range of possible couplings and set mass limits on the lowest excited gravitons state of up to 898 GeV.« less
  • A search for the lightest Kaluza-Klein mode of the graviton in the Randall-Sundrum model with a warped extra dimension is performed in the dielectron and diphoton channels. The data set used for the search corresponds to 5.4 fb -1 of data from pmore » $$\bar{p}$$ collisions at a center-of-mass energy of 1.96 TeV, collected with the D0 detector at the Fermilab Tevatron between July 2002 and Summer 2009. We search for resonances in the invariant mass spectrum of two electromagnetic showers from the decay of the graviton to either electron-positron pairs or photon pairs. To optimize the sensitivity, the dielectron and diphoton channels are analyzed separately, then the results are combined together in the end. We also investigate whether, due to the unique spin-2 nature of the graviton, the angular distribution of the final state particles can be used to significantly enhance the sensitivity of the search. We set 95% confidence level upper limits on the graviton production cross section times branching fraction into electron-positron pairs of between ~ 7 fb and ~ 0.5 fb for a range of graviton masses from 220 GeV and 1050 GeV, respectively. Compared with Randall-Sundrum model predictions, these results correspond to lower limits on the lightest graviton mass between 440 GeV and 1040 GeV, for the dimensionless graviton coupling to the Standard Model fields k/$$\bar{M}$$ Pl in the range from 0.01 to 0.1. In addition, for coupling k/$$\bar{M}$$ Pl of 0.01, gravitons with masses between 460 GeV and 560 GeV are also excluded at 95% confidence level. These results represent the most sensitive limits to date.« less
  • Using 5.4 fb{sup -1} of integrated luminosity from pp collisions at {radical}(s)=1.96 TeV collected by the D0 detector at the Fermilab Tevatron Collider, we search for decays of the lightest Kaluza-Klein mode of the graviton in the Randall-Sundrum model to ee and {gamma}{gamma}. We set 95% C.L. lower limits on the mass of the lightest graviton between 560 and 1050 GeV for values of the coupling k/M{sub Pl} between 0.01 and 0.1.
  • We have performed a search for new particles which decay to two photons using 1.2 fb{sup -1} of integrated luminosity from p{bar p} collisions at {radical}s=1.96 TeV collected using the CDF II Detector at the Fermilab Tevatron. We find the diphoton mass spectrum to be in agreement with the standard model expectation, and set limits on the cross section times branching ratio for the Randall-Sundrum graviton, as a function of diphoton mass. We subsequently derive lower limits for the graviton mass of 230 GeV/c{sup 2} and 850 GeV/c{sup 2}, at the 95% confidence level, for coupling parameters (k/{bar M}{sub pl})more » of 0.01 and 0.1 respectively.« less
  • We have performed a search for new particles which decay to two photons using 1.2 fb{sup -1} of integrated luminosity from pp collisions at {radical}(s)=1.96 TeV collected using the CDF II detector at the Fermilab Tevatron. We find the diphoton mass spectrum to be in agreement with the standard model expectation, and set limits on the cross section times branching ratio for the Randall-Sundrum graviton, as a function of diphoton mass. We subsequently derive lower limits for the graviton mass of 230 GeV/c{sup 2} and 850 GeV/c{sup 2}, at the 95% confidence level, for coupling parameters (k/M{sub Pl}) of 0.01more » and 0.1, respectively.« less