Download or read book Search for Metastable Heavy Charged Particles with Large Ionisation Energy Loss in Pp Collisions at sqrt s written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Many extensions of the Standard Model predict the existence of charged heavy long-lived particles, such as R-hadrons or charginos. These particles, if produced at the Large Hadron Collider, should be moving non-relativistically and are therefore identifiable through the measurement of an anomalously large specific energy loss in the ATLAS pixel detector. Measuring heavy long-lived particles through their track parameters in the vicinity of the interaction vertex provides sensitivity to metastable particles with lifetimes from 0.6 ns to 30 ns. A search for such particles with the ATLAS detector at the Large Hadron Collider is presented, based on a data sample corresponding to an integrated luminosity of \(18.4\) fb\(^{-1}\) of pp collisions at \(\sqrt{s} = 8\) TeV. No significant deviation from the Standard Model background expectation is observed, and lifetime-dependent upper limits on R-hadrons and chargino production are set. Gluino R-hadrons with 10 ns lifetime and masses up to 1185 GeV are excluded at 95 \(\%\) confidence level, and so are charginos with 15 ns lifetime and masses up to 482 GeV.

Download or read book Search for Metastable Heavy Charged Particles with Large Ionization Energy Loss in Pp Collisions at S written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This study presents a search for massive charged long-lived particles produced in pp collisions at √s = 13TeV at the LHC using the ATLAS experiment. The data set used corresponds to an integrated luminosity of 3.2 fb–1. Many extensions of the Standard Model predict the existence of massive charged long-lived particles, such as R-hadrons. These massive particles are expected to be produced with a velocity significantly below the speed of light, and therefore to have a specific ionization higher than any Standard Model particle of unit charge at high momenta. The Pixel subsystem of the ATLAS detector is used to measure the ionization energy loss of reconstructed charged particles and to search for such highly ionizing particles. The search presented here has much greater sensitivity than a similar search performed using the ATLAS detector in the √s = 8TeV data set, thanks to the increase in expected signal cross section due to the higher center-of-mass energy of collisions, to an upgraded detector with a new silicon layer close to the interaction point, and to analysis improvements. No significant deviation from Standard Model background expectations is observed, and lifetime-dependent upper limits on R-hadron production cross sections and masses are set. Gluino R-hadrons with lifetimes above 0.4 ns and decaying to qq¯ plus a 100 GeV neutralino are excluded at the 95% confidence level, with lower mass limit ranging between 740 and 1590 GeV. In the case of stable R-hadrons the lower mass limit at the 95% confidence level is 1570 GeV.

Download or read book Search for Metastable Heavy Charged Particles with Large Ionisation Energy Loss in Pp Collisions at arrow written by and published by . This book was released on 2015 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: The many extensions of the Standard Model predict the existence of charged heavy long-lived particles, such as R-hadrons or charginos. If produced at the Large Hadron Collider, these particles should be moving non-relativistically and are therefore identifiable through the measurement of an anomalously large specific energy loss in the ATLAS pixel detector. Measuring heavy long-lived particles through their track parameters in the vicinity of the interaction vertex provides sensitivity to metastable particles with lifetimes from 0.6 ns to 30 ns. A search for such particles with the ATLAS detector at the Large Hadron Collider is presented, based on a data sample corresponding to an integrated luminosity of 18.4 fb-1 of pp collisions at [arrow]"=8 TeV. No significant deviation from the Standard Model background expectation is observed, and lifetime-dependent upper limits on R-hadrons and chargino production are set. Gluino R-hadrons with 10 ns lifetime and masses up to 1185 GeV are excluded at 95 % confidence level, and so are charginos with 15 ns lifetime and masses up to 482 GeV.

Download or read book Search for Stable and Long lived Heavy Charged Particles in Electron positron Collisions at Center of Mass Energies from 130 to 209 GeV with the OPAL Detector at LEP written by Gabriele Benelli and published by . This book was released on 2003 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Search for Multiply Charged Heavy Stable Charged Particles in Data Collected with the CMS Detector written by and published by . This book was released on 2013 with total page 177 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several models of new physics yield particles that are massive, long-lived, and have an electric charge, Q, greater than that of the electron, e. A search for evidence of such particles was performed using 5.0 fb-1 and 18.8 fb-1 of proton-proton collision data collected at √s = 7 TeV and √s = 8 TeV, respectively, with the Compact Muon Solenoid detector at the Large Hadron Collider. The distinctive detector signatures of these particles are that they are slow-moving and highly ionizing. Ionization energy loss and time-of- flight measurements were made using the inner tracker and the muon system, respectively. The search is sensitive to 1e ≤

Download or read book Study of Parton Energy Loss in Heavy Ion Collisions Using Charged Particle Spectra Measured with CMS written by Austin A. Baty and published by . This book was released on 2019 with total page 245 pages. Available in PDF, EPUB and Kindle. Book excerpt: The phenomenology of the strong nuclear force is still not well understood at low momentum transfers and requires experimental input to constrain. Collisions of heavy ions at the Large Hadron Collider provide a unique opportunity to explore this kinematic region because they create a novel form of matter: the quark-gluon plasma (QGP). Using the CMS detector, spectra of charged particles originating from protonproton (pp), proton-lead (pPb), and lead-lead (PbPb) collisions at a center of mass energy per nucleon pair ( [square root of SNN) of 5.02 TeV are examined as a function of transverse momentum and centrality. Nuclear modification factors and fragmentation functions are constructed from these spectra. By comparing to pp collision reference spectra, a puzzle concerning previous measurements in pPb collisions is clarified. A strong suppression of particle production observed in PbPb collisions is also quantified. Finally, collisions of xenon nuclei are also studied to constrain the path length dependence of parton energy loss. The strength of energy loss is found to increase with both [square root of SNN and the average path length through the QGP. Comparisons to theoretical models and previous measurements indicate that the path length dependence is between linear and quadratic, as expected from a combination of collisional and radiative energy loss mechanisms.

Download or read book Search for Heavy Long lived Multi charged Particles in Pp Collisions at arrow written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for heavy long-lived multi-charged particles is performed using the ATLAS detector at the LHC. Data collected in 2012 at [arrow]" = 8 TeV from pp collisions corresponding to an integrated luminosity of 20.3 fb-1 are examined. Particles producing anomalously high ionisation, consistent with long-lived massive particles with electric charges from.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Search for Heavy Long lived Charged Particles with the ATLAS Detector in Pp Collisions at s written by Shikma Bressler and published by . This book was released on 2011 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Azimuthal Anisotropy of Charged Particles at High Transverse Momenta in PbPb Collisions at Sqrt s NN written by and published by . This book was released on 2012 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: The azimuthal anisotropy of charged particles in PbPb collisions at nucleon-nucleon center-of-mass energy of 2.76 TeV is measured with the CMS detector at the LHC over an extended transverse momentum (pt) range up to approximately 60 GeV. The data cover both the low-pt region associated with hydrodynamic flow phenomena and the high-pt region where the anisotropies may reflect the path-length dependence of parton energy loss in the created medium. The anisotropy parameter (v2) of the particles is extracted by correlating charged tracks with respect to the event-plane reconstructed by using the energy deposited in forward-angle calorimeters. For the six bins of collision centrality studied, spanning the range of 0-60% most-central events, the observed v2 values are found to first increase with pt, reaching a maximum around pt = 3 GeV, and then to gradually decrease to almost zero, with the decline persisting up to at least pt = 40 GeV over the full centrality range measured.

Download or read book Study of Charged Particles Associated with High p written by and published by . This book was released on 1982 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We report on the distributions of charged particles produced in association with high p/sub T/ prompt photons and neutral pions in pp collisions at .sqrt. s = 63 GeV and theta = 90° in the centre of mass. We find photons to be relatively unaccompained by other particles at small angles with respect to the photon, and thereby extract a measurement of the fraction of prompt photons due to bremsstrahlung production. The relative density of positive to negative particles in the system recoiling from the photon has been measured and compared with QCD motivated calculations.

Download or read book Search for Charged Massive Long lived Particles at sqrt s written by and published by . This book was released on 2012 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Search for Long lived Charged Particles in Proton proton Collisions at math Display written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Results are presented of a search for heavy stable charged particles produced in proton-proton collisions at √s = 13 TeV using a data sample corresponding to an integrated luminosity of 2.5 fb-1 collected in 2015 with the CMS detector at the CERN LHC. The search is conducted using signatures of anomalously high energy deposits in the silicon tracker and long time-of-flight measurements by the muon system. The data are consistent with the expected background, and upper limits are set on the cross sections for production of long-lived gluinos, top squarks, tau sleptons, and lepton-like long-lived fermions. These upper limits are equivalently expressed as lower limits on the masses of new states; the limits for gluinos, ranging up to 1610 GeV, are the most stringent to date. Furthermore, limits on the cross sections for direct pair production of long-lived tau sleptons are also determined.

Download or read book Charged Particle Transverse Momentum Spectra in Pp Collisions at Sqrt s written by and published by . This book was released on 2011 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The charged particle transverse momentum (pT) spectra are presented for pp collisions at sqrt(s)=0.9 and 7 TeV. The data samples were collected with the CMS detector at the LHC and correspond to integrated luminosities of 231 inverse microbarns and 2.96 inverse picobarns, respectively. Calorimeter-based high-transverse-energy triggers are employed to enhance the statistical reach of the high-pT measurements. The results are compared with both leading-order QCD and with an empirical scaling of measurements at different collision energies using the scaling variable xT = 2 pT/sqrt(s) over the pT range up to 200 GeV/c. Using a combination of xT scaling and direct interpolation at fixed pT, a reference transverse momentum spectrum at sqrt(s)=2.76 TeV is constructed, which can be used for studying high-pT particle suppression in the dense QCD medium produced in heavy-ion collisions at that centre-of-mass energy.

Download or read book Particle Ratios at High Transverse Momentum in Pp Collisions At Sqrt S written by and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The production of identified charged particles in pp collisions at .sqrt.s = 63 GeV with an identified high p/sub T/ trigger particle emitted in the central region is studied. The measurements were performed at the CERN ISR using the Axial Field Spectrometer. Trigger particle ratios, sigma(.pi./sup + -/)/ sigma(all/sup + -/), sigma(K/sup + -/) and sigma(p/sup + -/)/sigma(all/sup + -/) are presented for p/sub T/ from 5 GeV/c to 8 GeV/c. In addition sigma(.pi./sup + -/)/sigma(all/sup + -/) is presented in the p/sub T/ region from 2.5 GeV/c to 4.5 GeV/c. The charge compensation in the hemisphere containing the trigger particle is shown to depend strongly on the identity of the trigger particle and on the identity of the associated particles. 13 references.

Download or read book Tables of Energy Losses and Ranges of Heavy Charged Particles written by Walter H. Barkas and published by . This book was released on 1964 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Search for Stopped Long lived Particles Produced in Pp Collisions at 8 TeV at CMS written by Marissa L. Rodenburg and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: At the Large Hadron Collider counter-rotating proton beams are collided at sqrt(s) = 8 TeV. The Compact Muon Solenoid (CMS) is used to measure the energies and charges of the resulting cascade of particles produced in these collisions. This search focuses on the observation of massive, long-lived particles, such as the gluino, that would suggest new physics beyond the Standard Model. A custom trigger is used to probe time periods during which no proton collisions occur, thereby eliminating most backgrounds to the signal. The remaining backgrounds resulting from cosmic rays, beam-related effects, and instrumental noise, are further reduced using a series of sophisticated selection cuts. Candidate events passing all selection cuts are analyzed using a counting experiment and limits are placed on the cross sections and masses of the gluino and the supersymmetric top quark.