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Hep-Ex Publications

- Evidence for the Higgs boson decay to a bottom quark-antiquark pair. (arXiv:1709.07497v1 [hep-ex])
- $ZZ \to \ell^{+}\ell^{-}\ell^{\prime +}\ell^{\prime -}$ cross-section measurements and search for anomalous triple gauge couplings in 13 TeV $pp$ collisions with the ATLAS detector. (arXiv:1709.07703v1 [hep-ex])
- Spin Precession Experiments for Light Axionic Dark Matter. (arXiv:1709.07852v1 [hep-ph])
- Search for leptophobic Z' bosons decaying into four-lepton final states in proton-proton collisions at sqrt(s) = 8 TeV. (arXiv:1701.01345v2 [hep-ex] UPDATED)
- Fiducial, total and differential cross-section measurements of $t$-channel single top-quark production in $pp$ collisions at 8 TeV using data collected by the ATLAS detector. (arXiv:1702.02859v3 [hep-ex] UPDATED)



The Caltech CMS Group
Toyoko Orimoto
Harvey Newman
Adi Bornheim
Artur Apresyan
Maria Spiropulu
Chris Rogan
Julian Bunn
Alex Mott
Piotr Traczyk
Javier Duarte
Yong Yang
R.Y. Zhu
Yousi MA
Massimiliano Chiorboli
Rick Wilkinson
Dorian Kcira
Jan Veverka
Yi Chen
Flavia de Almeida Dias
Marat Gataullin
Emanuele Di Marco
Vladlen Timciuc


H. Newman, M. Spiropulu

Physics Research Group

A. Apresyan, A. Bornheim, J. Bunn, Y. Chen, M. Chiorboli, E. Di Marco, J. Duarte, M. Gataullin, D. Kcira, Y. Ma, A. Mott, H. Newman, T. Orimoto, C. Rogan, M. Spiropulu, V. Timciuc, P. Traczyk, J. Veverka, R. Wilkinson, Y. Yang, R.Y. Zhu

Research Highlights

The discovery of the Higgs-like particle [discovery paper] at the Large Hadron Collider has propelled science in a uncharted territory. The Higgs boson decays instantly into lighter particles. The Caltech group has been making possible the exquisitely calibrated photon calorimetry measurements [1] needed to tease out the Higgs or other exotic particles that decay to photons. We work on the diboson channels for the Higgs (γγ, ZZ, WW, Zγ) as well as the Higgs properties measurements. The LHC collisions may also produce particles of dark matter, but these heavy particles would be invisible, recoiling from a complex spray of visible particles. For dark matter, the group is pursuing a discovery strategy for signals with missing energy and momentum from unseen particles: using the earliest data to commission CMS calorimetry for jets and missing energy [2], validating the understanding of these signatures in similar Standard Model processes, and implementing new data-driven techniques [3] to maximize the inclusive CMS sensitivity to dark matter. The group pioneered a new set of analysis techniques and kinematic variables (razor [prd 2010] ) that are now used in searches for new physics and are intended to assist discovery and characterization of new particles. A crucial aspect of the Caltech approach is taming the information flow from LHC collisions: a vertically integrated approach to triggering, dataset definition, data quality monitoring, software development, distributed computing and collaborative systems, resulting in the the robust framework required to characterize discovery signals [4]. We have a calorimetry R&D program and developing trigger strategies for the upgraded CMS detector for high luminosity and high energy running.


[discovery paper] Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC / CMS Collaboration, arXiv:1207.7235 ; CMS-HIG-12-028 ; CERN-PH-EP-2012-220; 31 Jul 2012. - 59 p., - Published in : Phys. Lett. B 716 (2012) 30-61
[1] Intercalibration of the CMS Electromagnetic Calorimeter with Neutral Pion Decays, Nuclear Physics B Volume 197, Issue 1, 15 December 2009, pp. 147-150, doi:10.1016/j.nuclphysbps.2009.10.054 (2009)
[2] SUSY at the LHC: Examples of search, navigation and orientation, Eur.Phys.J.C59(2009) Springer Berlin / Heidelberg, doi:10.1140/epjc/s10052-008-0778-0 (2008).
[3] Study of Z production in association with jets in proton-proton collisions at √s = 10 TeV with the CMS detector at the CERN LHC, CMS-PAS-EWK-08-006 (2009) and Study of the ratio of W+jets to Z+jets in proton--proton collisions at √s = 10 TeV with the CMS detector at the CERN LHC, CMS-PAS-EWK-08-006 (2009)
[prd 2010] Inclusive search for squarks and gluinos in pp collisions at √s = 7 TeV / CMS Collaboration, arXiv:1107.1279; CMS-SUS-10-009; CERN-PH-EP-2011-099.- Geneva : CERN, 2012 - 42 p. - Published in : Phys. Rev. D 85 (2012) 012004 APS
[4] Missing energy look-alikes with 100 pb-1 at the CERN LHC, Phys. Rev. D 78, 075008 (2008).


- Marcus Woo, Space Daily: "A Hint of Higgs - Update from the LHC", August 18, 2011.
- Dennis Overbye of NYT reporting from Caltech HEP Lauritsen Lab, March 30-31, 2010.

- SURF/MURF/CERN undergraduate summer students 2010/2011