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Author : Amitabha Das
Release : 2008
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Book Synopsis Search for Randall-Sundrum Gravitons in Dilepton and Diphoton Final States with 1 Fb-1 of Data by : Amitabha Das
Download or read book Search for Randall-Sundrum Gravitons in Dilepton and Diphoton Final States with 1 Fb-1 of Data written by Amitabha Das. This book was released on 2008. Available in PDF, EPUB and Kindle. Book excerpt:
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Release : 2007
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Book Synopsis Search for Randall-Sundrum Gravitons in Dilepton and Diphoton Final States with 1 Fb-1 of Data by :
Download or read book Search for Randall-Sundrum Gravitons in Dilepton and Diphoton Final States with 1 Fb-1 of Data written by . This book was released on 2007. Available in PDF, EPUB and Kindle. Book excerpt: 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 and 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 ee− and [gamma][gamma] 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.
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Release : 2010
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Book Synopsis Search for Randall-Sundrum Gravitons in the Dielectron and Diphoton Final States with 5.4fb$^{-1}$ of Data from $p\bar{p}$ Collisions at $\sqrt{s} by :
Download or read book Search for Randall-Sundrum Gravitons in the Dielectron and Diphoton Final States with 5.4fb$^{-1}$ of Data from $p\bar{p}$ Collisions at $\sqrt{s} written by . This book was released on 2010. Available in PDF, EPUB and Kindle. Book excerpt: Using 5.4 fb−1 of integrated luminosity from p{bar p} collisions at √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 GeV and 1050 GeV for values of the coupling k/{bar M}{sub Pl} between 0.01 and 0.1.
Author : Ning Zhou
Release : 2010
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Book Synopsis Search for Randall-Sundrum Gravitons in Dielectron and Diphoton Final States with 5.4 Fb-1 of Do Data by : Ning Zhou
Download or read book Search for Randall-Sundrum Gravitons in Dielectron and Diphoton Final States with 5.4 Fb-1 of Do Data written by Ning Zhou. This book was released on 2010. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Release : 2010
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Book Synopsis Search for Randall-Sundrum Gravitons in Dielectron and Diphoton Final States with 5.4fb-1 of D0 Data by :
Download or read book Search for Randall-Sundrum Gravitons in Dielectron and Diphoton Final States with 5.4fb-1 of D0 Data written by . This book was released on 2010. Available in PDF, EPUB and Kindle. Book excerpt: 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 p{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 (almost equal to) 7 fb and (almost equal to) 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}{sub Pl} in the range from 0.01 to 0.1. In addition, for coupling k/{bar M}{sub 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.
