H. Baer

Final technical report: From colliders to cosmology in the LHC era

Precise mapping of the magnetic field in the CMS barrel yoke using cosmic rays

Journal of Instrumentation, 2010

The CMS detector is designed around a large 4 T superconducting solenoid, enclosed in a 12 000-to... more The CMS detector is designed around a large 4 T superconducting solenoid, enclosed in a 12 000-tonne steel return yoke. A detailed map of the magnetic field is required for the accurate simulation and reconstruction of physics events in the CMS detector, not only in the inner tracking region inside the solenoid but also in the large and complex structure of the steel yoke, which is instrumented with muon chambers. Using a large sample of cosmic muon events collected by CMS in 2008, the field in the steel of the barrel yoke has been determined with a precision of 3 to 8% depending on the location.

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Performance of the CMS drift-tube chamber local trigger with cosmic rays

Journal of Instrumentation, 2010

The performance of the Local Trigger based on the drift-tube system of the CMS experiment has bee... more The performance of the Local Trigger based on the drift-tube system of the CMS experiment has been studied using muons from cosmic ray events collected during the commissioning of the detector in 2008. The properties of the system are extensively tested and compared with the simulation. The effect of the random arrival time of the cosmic rays on the trigger performance is reported, and the results are compared with the design expectations for proton-proton collisions and with previous measurements obtained with muon beams.

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Commissioning and performance of the CMS silicon strip tracker with cosmic ray muons

Journal of Instrumentation, 2010

During autumn 2008, the Silicon Strip Tracker was operated with the full CMS experiment in a comp... more During autumn 2008, the Silicon Strip Tracker was operated with the full CMS experiment in a comprehensive test, in the presence of the 3.8 T magnetic field produced by the CMS superconducting solenoid. Cosmic ray muons were detected in the muon chambers and used to trigger the readout of all CMS sub-detectors. About 15 million events with a muon in the tracker were collected. The efficiency of hit and track reconstruction were measured to be higher than 99% and consistent with expectations from Monte Carlo simulation. This article details the commissioning and performance of the Silicon Strip Tracker with cosmic ray muons.

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Measurement of the Muon Stopping Power in Lead Tungstate with the Electromagnetic Calorimeter in CMS

Journal of Physics: Conference Series, 2011

A large sample of cosmic ray events collected by the CMS detector has been exploited to measure t... more A large sample of cosmic ray events collected by the CMS detector has been exploited to measure the muon stopping power in the lead tungstate (PbWO 4 ) of the electromagnetic calorimeter. The events were recorded in October-November 2008, during commissioning runs of the CMS detector with the solenoid at the nominal field strength of 3.8 T. The measurement spans a momentum range from 5 to 1000 GeV/c. The results are consistent with the expectations over the entire range. A comparison of collision losses with radiative losses allowed for a first experimental determination of muon critical energy in lead tungstate, measured to be 160 +5 -6 (stat.)±8 (syst.) GeV, in agreement with expectations.

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Expectations for two- and three-jet events at HERA

Zeitschrift für Physik C Particles and Fields, 1989

... Lett. 160B (1985) 349; Z. Phys. C--Particles and Fields 30 (1986) 341 8. For a review of HERA... more

The SUSY Les Houches Accord Project

The work contained herein constitutes a report of the “Beyond the Standard Model” working group f... more The work contained herein constitutes a report of the “Beyond the Standard Model” working group for the Workshop “Physics at TeV Colliders”, Les Houches, France, 26 May–6 June, 2003. The research presented is original, and was performed specifically for the workshop. Tools for calculations in the minimal supersymmetric standard model are presented, including a comparison of the dark matter relic density predicted by public codes. Reconstruction of supersymmetric particle masses at the LHC and a future linear collider facility is examined. Less orthodox supersymmetric signals such as non-pointing photons and Rparity violating signals are studied. Features of extra dimensional models are examined next, includingmeasurement strategies for radions and Higgs’, as well as the virtual effects of Kaluza Klein modes of gluons. An LHC search strategy for a heavy top found in many little Higgs model is presented and finally, there is an update on LHC Z? studies

Signatures for fourth-generation quarks and a heavy top quark at the Superconducting Super Collider

Physical Review D, 1988

We examine methods for detection of new heavy quarks at the Superconducting Super Collider where ... more

Searching for R-Parity Violation at Run-II of the Tevatron

arXiv (Cornell University), Jun 22, 1999

We present an outlook for possible discovery of supersymmetry with broken R-parity at Run II of t... more We present an outlook for possible discovery of supersymmetry with broken R-parity at Run II of the Tevatron. We first present a review of the literature and an update of the experimental bounds. In turn we then discuss the following processes: 1. Resonant slepton production followed by Rp decay, (a) via LQD c and (b) via LLE c . 2. How to distinguish resonant slepton production from Z ′ or W ′ production. 3. Resonant slepton production followed by the decay to neutralino LSP, which decays via LQD c . 4. Resonant stop production followed by the decay to a chargino, which cascades to the neutralino LSP. 5. Gluino pair production followed by the cascade decay to charm squarks which decay directly via L1Q2D c 1 . 6. Squark pair production followed by the cascade decay to the neutralino LSP which decays via L1Q2D c 1 . 7. MSSM pair production followed by the cascade decay to the LSP which decays (a) via LLE c , (b) via LQD c , and (c) via U c D c D c , respectively. 8. Top quark and top squark decays in spontaneous Rp. 6) Throughout the rest of this section we shall denot the parameter κ as ǫ.

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On the squark and gluino mass limits from the CERN pp̄ collider

Physics Letters B, 1987

format_quoteUA1 collaboration established squark mass limits: m_s > 70 GeV and m_g > 60 GeV, based on specific experimental assumptions.format_quote

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Is``just-so''Higgs splitting needed for t? b?? Yukawa unified SUSY GUTs?

Possible heavy lepton signals at p colliders

Physics Letters B, 1983

... HEAVY LEPTON SIGNALS AT Pp COLLIDERS V. BARGER, H. BAER Physics Department, University of Wis... more

Prospects for supersymmetry at the Fermilab collider

Physical Review D, 1986

... SUSY particles (SISP's) was imminent. ... Because of the sharp decrease of cross section... more

SEARCHING FOR SUPERSYMMETRY AT e+e− SUPERCOLLIDERS

International Journal of Modern Physics A, 1989

We study the signals resulting from the production and subsequent decays of heavy sleptons, sneut... more We study the signals resulting from the production and subsequent decays of heavy sleptons, sneutrinos and all the charginos [Formula: see text] and neutralinos [Formula: see text] at ultrahigh energy e+e− colliders. In contrast to existing studies that assume that supersymmetric particles directly decay to the lightest supersymmetric particle (taken here to be the lightest neutralino, [Formula: see text]) which then escapes detection, we incorporate realistic decay patterns using the minimal supersymmetry model as a guide for the masses and mixing angles in the gaugino-Higgsino sector. We show that very heavy sleptons and sneutrinos often decay into heavier charginos and neutralinos which themselves often decay into real W and Z0 bosons and lighter [Formula: see text]'s and [Formula: see text]'s. This results in a considerably softer missing transverse momentum [Formula: see text] spectrum than would be expected if sparticles decayed directly to the [Formula: see text] so t...

Les Houches

The work contained herein constitutes a report of the "Beyond the Standard Model''... more The work contained herein constitutes a report of the "Beyond the Standard Model'' working group for the Workshop "Physics at TeV Colliders", Les Houches, France, 2-20 May, 2005. We present reviews of current topics as well as original research carried out for the workshop. Supersymmetric and non-supersymmetric models are studied, as well as computational tools designed in order to facilitate their phenomenology.

BSM physics in the LHC13 era

format_quoteQuestions regarding weak scale SUSY arise due to LHC8 findings, necessitating re-evaluation of naturalness in physics theories.format_quote

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Two-photon backgrounds for the intermediate mass Higgs boson

Physics Letters B, 1988

... [6] JF Gunion, GL Kane and J. Wudka, UCD-87-28. [7] RJ Dewitt, LM Jones, JD Sullivan, DE Will... more

ILC as a natural SUSY discovery machine and precision microscope: From light Higgsinos to tests of unification

Physical review, May 20, 2020

The requirement of electroweak naturalness in simple supersymmetric models implies the existence ... more The requirement of electroweak naturalness in simple supersymmetric models implies the existence of a cluster of four light Higgsinos with a mass ∼100-300 GeV, the lighter the better. While such light compressed spectra may be challenging to observe at the LHC, the International Linear e þ e -Collider (ILC) with ffiffi ffi s p > 2m Higgsino would serve as both a SUSY discovery machine and a precision microscope. We study Higgsino pair production signatures at the ILC based on a full, GEANT4-based simulation of the ILD detector concept. We examine several benchmark scenarios that may be challenging for discovery at the HL-LHC due to mass differences between the Higgsino states between 20 and 4 GeV. Assuming ffiffi ffi s p ¼ 500 GeV and 1000 fb -1 of integrated luminosity, the individual Higgsino masses can be measured to 1%-2% precision in the case of the larger mass differences, and at the level of 5% for the smallest mass difference case. The Higgsino mass splittings are sensitive to the electroweak gaugino masses and allow extraction of gaugino masses to ∼3%-20% (depending on the model). Extrapolation of gaugino masses via renormalization group running can test the hypothesis of gaugino mass unification. We also examine a case with natural generalized mirage mediation, where the unification of gaugino masses at an intermediate scale apparently gives rise to a natural SUSY spectrum somewhat beyond the reach of HL-LHC.

format_quoteTop squark masses in natural SUSY limited to ∼3 TeV, yielding Higgs mass m_h < 127 GeV, influencing LHC's reach.format_quote

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HadronicW-decays at HERA

Zeitschrift f�r Physik C Particles and Fields, 1989

... should result in a clearly visible W signal in the dijet invariant mass spectra both for dije... more

Event generators for discovery physics

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