Alternate Title

Direct photons as probes of low mass strings at the CERN LHC

Abstract

The LHC program will include the identification of events with single prompt high-k_\perp photons as probes of new physics. We show that this channel is uniquely suited to search for experimental evidence of TeV-scale open string theory. At the parton level, we analyze single photon production in gluon fusion, gg \to \gamma g, with open string states propagating in intermediate channels. If the photon mixes with the gauge boson of the baryon number, which is a common feature of D-brane quivers, the amplitude appears already at the string disk level. It is completely determined by the mixing parameter (which is actually determined in the minimal theory) -- and it is otherwise model-(compactification-) independent. We discuss the string signal cross sections as well as the QCD background. The present analysis takes into account the recently obtained decay widths of first Regge recurrences, which are necessary for more precise determination of these cross sections in the resonant region. A vital part of the background discussion concerns the minimization of misidentified \pi^0's emerging from high-p_\perp jets. We show that even for relatively small mixing, 100 fb^-1 of LHC data could probe deviations from standard model physics associated with TeV-scale strings at a 5\sigma significance, for M_{\rm string} as large as 2.3 TeV. It is also likely that resonant bumps could be observed with approximately the same signal-to-noise ratio.

Notes

Originally posted at http://arxiv.org/abs/0804.2013v4. Preprint of an article published in Physical Review D, v.78 no.1, 2008.

Keywords

high energy physics phenomenology, LHC

Subject Categories

Large Hadron Collider (France and Switzerland), Photons, String models

Disciplines

Physics

Publication Date

2008


View Full Text

Click button above to open, or right-click to save.

Included in

Physics Commons

Share

COinS