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Polarised Drell-Yan physics at COMPASS
Title
Polarised Drell-Yan physics at COMPASS, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator
Franco, Celso
Date
2013-09-15, 2013-09-15
Publisher
IIT Press
Description
The COMPASS experiment at CERN is one of the leading experiments studying the spin structure of the nucleon. Until now, the Parton...
Show moreThe COMPASS experiment at CERN is one of the leading experiments studying the spin structure of the nucleon. Until now, the Parton Distribution Functions (PDFs) and the Transverse Momentum Dependent Parton Distribution Functions (TMD PDFs) of protons and deuterons have been studied in Semi-Inclusive Deep Inelastic Scattering (SIDIS) measurements. The polarised Drell-Yan (DY) process is a complementary way to access the TMD PDFs, as it allows us to measure convolutions of only PDFs without involving fragmentation functions (FFs). COMPASS aims to perform the first ever polarised DY experiment in the world, which is foreseen to start in late 2014. By detecting dimuons from DY events we will be able to extract azimuthal spin asymmetries, each containing a convolution of two TMD PDFs, one from a negative pion beam with a momentum of 190 GeV/c and the other one from a transversely polarised proton target (NH₃). After their disentangling we can access four of the eight TMD PDFs needed to describe the nucleon structure at leading twist, like the Sivers and the Boer-Mulders functions. The opportunity to study, in the same experiment, the TMD PDFs from both SIDIS and DY processes is unique at COMPASS. Therefore, we are in privileged conditions to confirm or to deny the expected sign change in Sivers and Boer-Mulders functions when accessed via DY or SIDIS processes. An overview of the preparation and future measurements of the polarised DY experiment will be provided.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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Measurement of anisotropic radial flow rapidity
Title
Measurement of anisotropic radial flow rapidity, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator
Wu, Yuafang, Li, Lin, Li, Na
Date
2013-09-15, 2013-09-15
Publisher
IIT Press
Description
Using the sample of Au + Au collisions at 200 GeV generated by the AMPT with string melting model, the anisotropic amplitudes of azimuthal...
Show moreUsing the sample of Au + Au collisions at 200 GeV generated by the AMPT with string melting model, the anisotropic amplitudes of azimuthal distributions of total transverse momentum, mean radial (transverse) momentum, and multiplicity are first presented and compared. It shows that the azimuthal distribution of mean radial momentum well characterizes the radial expansion. So a measurement of the azimuthal distribution of mean transverse (radial) rapidity of final state particles is suggested. We further show that the isotropic part of the suggested distribution is the combination of isotropic radial expansion and thermal motion. The anisotropic amplitude characterizes the anisotropic radial flow, and coincides with the parameter of anisotropic radial flow rapidity extracted from a generalized blast-wave parametrization.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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Diffractive cross sections implemented in PYTHIA8-MBR VS LHC results
Title
Diffractive cross sections implemented in PYTHIA8-MBR VS LHC results, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator
Goulianos, Konstantin
Date
2013-09-15, 2013-09-15
Publisher
IIT Press
Description
Diffractive cross sections implemented in the pythia8-mbr Monte Carlo simulation are reviewed and compared to results obtained at the Large...
Show moreDiffractive cross sections implemented in the pythia8-mbr Monte Carlo simulation are reviewed and compared to results obtained at the Large Hadron Collider.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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Searching for W' bosons at LHC with single top production
Title
Searching for W' bosons at LHC with single top production, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator
Duffty, Daniel, Sullivan, Zack
Date
2013-09-15, 2013-09-15
Publisher
IIT Press
Description
One of the strengths of the LHC is its capacity for the discovery of new physics. As a consequence of many BSM theories, W′ bosons make an...
Show moreOne of the strengths of the LHC is its capacity for the discovery of new physics. As a consequence of many BSM theories, W′ bosons make an ideal particle to search for to constrain many models. One mode in particular has relatively low background: Single top quark production mediated by a W′ boson. For W′ masses less than 1500 GeV, all the decay products of the top quark are visible, and the strongest channel is the top’s decay into an electron or muon, with the associated neutrino and a bottom jet. As the W′ mass increases, the decay products from the highly boosted top and bottom quarks from the W′ appear as fat jets; boosted top tagging algorithms abound, and we propose a boosted bottom tag to set an exclusion limit of 2750 GeV for standard model-like couplings with existing 8 TeV data.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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Physics implications of correlation data from the RHIC and LHC heavy-ion programs
Title
Physics implications of correlation data from the RHIC and LHC heavy-ion programs, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator
Ray, R. L.
Date
2013-09-15, 2013-09-15
Publisher
IIT Press
Description
Two-dimensional angular correlation data from the STAR experiment at RHIC and from the LHC experiments provide critical information about...
Show moreTwo-dimensional angular correlation data from the STAR experiment at RHIC and from the LHC experiments provide critical information about dynamical processes in relativistic heavy-ion collisions. The principal correlation structures of interest are a broad jet-related peak at small relative azimuth (φ) extending to large relative pseudorapidity (η), the dijet ridge at large relative azimuth, and an independent double ridge on φ represented by a quadrupole function. The broad peak at small relative azimuth has been attributed, in large part, to initial-state fluctuations and hydrodynamic flow which produce higher-order harmonics on φ. That conjecture is challenged in this paper. It is shown that the net effect of additional higher harmonic model elements is to describe small, non-Gaussian (NG) shapes in the broad jet-related peak. The quadrupole correlation, which is also conventionally attributed to hydrodynamic flow, is considered within the Balitsky - Fadin - Kuraev - Lipatov (BFKL) Pomeron framework. Preliminary results using this model for the quadrupole correlation for particle production from 200 GeV p + p collisions are shown to be consistent with recent data from STAR.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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STAR Results from the RHIC Beam Energy Scan
Title
STAR Results from the RHIC Beam Energy Scan, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator
Wang, Hui
Date
2013-09-15, 2013-09-15
Publisher
IIT Press
Description
The Beam Energy Scan Program is launched by RHIC to study the QCD phase diagram. The goal is to explore the possible QCD phase boundary and...
Show moreThe Beam Energy Scan Program is launched by RHIC to study the QCD phase diagram. The goal is to explore the possible QCD phase boundary and search for possible QCD critical point. In 2010 and 2011, experiments collected data at √sNN=7.7, 11.5, 19.6, 27, 39 and 62.4 GeV, covering a wide range of baryon chemical potential from μB 420 to 70 MeV. In this presentation, we will report some latest results of the Beam Energy Scan Program from the STAR collaboration.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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Inclusive measurements at HERA from low to high x
Title
Inclusive measurements at HERA from low to high x, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator
Behnke, Olaf
Date
2013-09-15, 2013-09-15
Publisher
IIT Press
Description
New inclusive Deep Inelastic Scattering (DIS) measurements are presented, obtained with the H1 and ZEUS detectors at HERA. The results...
Show moreNew inclusive Deep Inelastic Scattering (DIS) measurements are presented, obtained with the H1 and ZEUS detectors at HERA. The results comprise (flavour) inclusive DIS cross sections as well as inclusive charm production. In the area of inclusive DIS, both H1 and ZEUS completed last year their high Q2 Neutral and Charged current measurements exploiting the large statistics from the HERA II running period. For inclusive charm production, H1 and ZEUS published a combination of numerous existing measurements based on various tagging methods. Among other things a precise determination of the running charm quark mass mc(mc) was obtained from the combined data.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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Boosted heavy particles and jet substructure with the CMS detector
Title
Boosted heavy particles and jet substructure with the CMS detector, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator
Marchesini, Ivan
Date
2013-09-15, 2013-09-15
Publisher
IIT Press
Description
In the last years, the understanding of jets and jet substructure has become increasingly important, in particular in the context of new...
Show moreIn the last years, the understanding of jets and jet substructure has become increasingly important, in particular in the context of new physics searches. Many new physics models involve highly boosted hadronically-decaying particles, which result in jet-like objects with large masses and an intrinsic substructure. Discrimination of these heavy jets from ordinary quark and gluon jets is possible through a plethora of new techniques. The understanding of jets can be exploited also for the identification of pileup jets and for the discrimination between quark jets and gluon jets. A sampling of these techniques is discussed together with their validation on collider data recorded in proton-proton collisions at √s = 8TeV with the CMS detector in the year 2012. The commissioning in the boosted regime of algorithms used to identify jets originating from bottom quarks is also discussed. Many studies have highlighted the potential of using jet substructure techniques to improve the sensitivity in physics searches. An overview of recent CMS results employing these techniques is presented.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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High-order cumulants from the 3D O(1) and O(4) spin models
Title
High-order cumulants from the 3D O(1) and O(4) spin models, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator
Pan, Xue, Wu, Yuafang, Chen, X. S., Chen, Lizhu
Date
2013-09-15, 2013-09-15
Publisher
IIT Press
Description
We simulate the 3D O(1) (Ising) and O(4) spin models by the Monte Carlo method. Interesting high-order cumulants from the 3D Ising and O(4)...
Show moreWe simulate the 3D O(1) (Ising) and O(4) spin models by the Monte Carlo method. Interesting high-order cumulants from the 3D Ising and O(4) universality classes are presented and discussed. They all show the non-monotonic or sign change behavior. The critical behavior is instructive to that of the high-order cumulants of the net baryon number in the QCD phase transitions. Maybe it’s difficult to distinguish the universality classes by the high-order cumulants in the heavy ion collisions.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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Influence of the target on multiparticle production in the forward domain in p+Pb collisions at 158 GeV
Title
Influence of the target on multiparticle production in the forward domain in p+Pb collisions at 158 GeV, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator
Rybczyński, Maciej
Date
2013-09-15, 2013-09-15
Publisher
IIT Press
Description
In this talk we show the influence of the target on multiparticle production in the forward hemisphere in p+Pb collisions at top SPS energy....
Show moreIn this talk we show the influence of the target on multiparticle production in the forward hemisphere in p+Pb collisions at top SPS energy. The multiplicity distributions appear to be almost target independent in the projectile fragmentation domain and the effect of fluctuations of the number of target participants is not seen in the projectile fragmentation region. We compare the obtained results with those for p+p interactions and predictions of models.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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The potential importance of low luminosity and high energy at the LHC
Title
The potential importance of low luminosity and high energy at the LHC, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator
White, Alan R.
Date
2013-09-15, 2013-09-15
Publisher
IIT Press
Description
Low luminosity runs at higher LHC energy could provide definitive evidence for an electroweak scale sextet quark sector of QCD that produces...
Show moreLow luminosity runs at higher LHC energy could provide definitive evidence for an electroweak scale sextet quark sector of QCD that produces electroweak symmetry breaking and dark matter within the bound-state S-Matrix of QUD - a massless, weak coupling, infra-red fixed-point, SU(5) field theory that might underly and unify the full Standard Model.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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Minimum-bias angular and trigger-associated correlations from 200 GeV p-p collisions: jets, flows, centrality, and the underlying event
Title
Minimum-bias angular and trigger-associated correlations from 200 GeV p-p collisions: jets, flows, centrality, and the underlying event, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator
Prindle, D.
Date
2013-09-15, 2013-09-15
Publisher
IIT Press
Description
The mechanisms leading to the hadronic final state of high-energy proton-proton collisions remain an unresolved issue at the RHIC and LHC. A...
Show moreThe mechanisms leading to the hadronic final state of high-energy proton-proton collisions remain an unresolved issue at the RHIC and LHC. A substantial contribution to the hadronic final state from minimum-bias (MB) jets is dominated by non-perturbative processes and may provide the common base for any high-energy dijet. Observation of a same-side (on azimuth)“ridge” in LHC p-p collisions suggests to some that hydrodynamic flows may play a role in that small system at higher energies. The issue of p-p centrality vs triggered jets has emerged in the context of gluon trans- verse distributions in the proton inferred from DIS data. Attempts have been made to isolate and study the underlying event (UE) complementary to triggered dijets, and it is suggested that multiple parton interactions may contribute to the UE. Reference [1] considered theoretical and experimental results for UE systematics and p-p centrality in the context of a two-component (soft+hard) model derived from single-particle pt spectrum nch systematics. The study concluded that there may be a substantial contribution to the UE from the triggered dijet and that p-p centrality is not controlled significantly by a jet trigger condition (if p-p centrality is relevant at all). Further study of two-particle correlations in p-p collisions was called for, particularly the nch dependence of MB correlations. We report a comprehensive study of MB (no pt cuts) angular correlations and trigger-associated (TA) yt correlations (transverse rapidity yt = ln[(mt + pt)/mπ]) from 200 GeV p-p collisions. Angular correlations are characterized by 2D model fits that accurately distinguish among proton dissociation structure (soft), jet-related structure (hard) and a nonjet azimuth quadrupole. All angular correlations are simply represented by a (2+1)-component model. The hard and quadrupole component scale simply with the soft-component multiplicity ns, clarifying the role of centrality and the eikonal model in p-p collisions. 2D TA correlations project to a marginal 1D trigger spectrum that can be simply predicted from pt spec- trum nch dependence. 2D TA distributions can then be processed to reveal MB jet fragment (hard component) systematics comparable to measured fragmentation functions. Hard-component azimuth dependence relative to the trigger relates to UE studies. From TA analysis we can establish the kinematic limits of jet fragment production in p-p collisions.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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Particle production sources in heavy ion collisions at RHIC and LHC
Title
Particle production sources in heavy ion collisions at RHIC and LHC, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator
Wolschin, Georg
Date
2013-09-15, 2013-09-15
Publisher
IIT Press
Description
A nonequilibrium statistical relativistic diffusion model (RDM) with three sources is applied to the analysis of charged-hadron distributions...
Show moreA nonequilibrium statistical relativistic diffusion model (RDM) with three sources is applied to the analysis of charged-hadron distributions in Au–Au collisions at RHIC energies, in Pb–Pb collisions at the current LHC energy of 2.76 TeV, and in p–Pb at 5.02 TeV. The relative sizes of the particle production sources at RHIC and LHC energies are investigated in pseudorapidity space as functions of incident energy. The midrapidity source that arises mostly from gluon-gluon collisions becomes more important than the fragmentation sources as the energy increases from RHIC to LHC.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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Study of pp interactions at high multiplicity at U-70
Title
Study of pp interactions at high multiplicity at U-70, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator
Aleev, A., Avdeichikov, V., Balandin, V., Borzunov, Yu., Chencov, Yu., Dunin, V., Furmanec, N., Kekelidze, G., Kireev, V., Kokoulina, E., Ladygin, V., Myalkovsky, V., Nikitin, V., Peshehonov, V., Petukhov, Yu., Rufanov, I., Yukaev, A., Zhidkov, N., Basiladze, S., Bogdanova, G., Erofeeva, I., Grishin, N., Grishkevich, Ya., Karmanov, D., Kramarenko, V., Leflat, A., Merkin, M., Popov, V., Tihonova, L., Vishnevskaya, A., Volkov, V., Voronin, A., Zverev, E., Ardashev, E., Afonin, A., Golovkin, V., Golovnya, S., Gorokhov, S., Kholodenko, A., Kiryakov, A., Kurchaniniv, L., Lobanov, I., Lobanova, E., Mitrofanov, G., Petrov, V., Pleskach, A., Polkovnikov, M., Ronzhin, V., Ryadovikov, V., Senko, V., Soldatov, M., Shalanda, N., Tsyupa, Yu., Vorobiev, A., Yakimchuk, V., Zapolsky, V., Kutov, A.
Date
2013-09-15, 2013-09-15
Publisher
IIT Press
Description
The E190 Experiment is aimed at the search for collective phenomena in a quark-gluon system and a hadron system. It is carried out at U-70 in...
Show moreThe E190 Experiment is aimed at the search for collective phenomena in a quark-gluon system and a hadron system. It is carried out at U-70 in IHEP, Protvino. The evidence of Bose-Einstein condensation of pions has been confirmed with a twofold increasing of sampling at a level of 7 standard deviations. We study soft photon (smaller than 60 MeV) yield by using of an electromagnetic calorimeter with low energy threshold. In the gluon dominance model we explain multiparticle production by the active gluons. In this model the estimation of the contribution of charge exchange has been obtained.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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Proton structure from multiparticle contribution to elastic pp-scattering at 7 TeV
Title
Proton structure from multiparticle contribution to elastic pp-scattering at 7 TeV, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator
Dremin, I. M.
Date
2013-09-15, 2013-09-15
Publisher
IIT Press
Description
The parton content of protons gets strong peripheral contribution at 1 fm from multiparticle dynamics as revealed by the overlap function in...
Show moreThe parton content of protons gets strong peripheral contribution at 1 fm from multiparticle dynamics as revealed by the overlap function in the unitarity condition for elastic pp-scattering at 7 TeV.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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Improved isolation of the p-p underlying event based on minimum-bias trigger-associated hadron correlations
Title
Improved isolation of the p-p underlying event based on minimum-bias trigger-associated hadron correlations, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator
Trainor, Thomas, Prindle, Duncan J.
Date
2013-09-15, 2013-09-15
Publisher
IIT Press
Description
Some aspects of hadron production in p-p collisions remain unresolved, including the low-hadron-momentum structure of high-parton-energy...
Show moreSome aspects of hadron production in p-p collisions remain unresolved, including the low-hadron-momentum structure of high-parton-energy dijets, separation of triggered dijets from the underlying event (UE), the systematics of multiple parton interactions and possible systematic underestimation of dijet contributions to high-energy nuclear collisions. In this study we apply a minimum-bias trigger-associated (TA) correlation analysis to p-p collisions. We extract a hard component from TA correlations that can be compared with measured jet fragment systematics derived from e+-e− collisions. The kinematic limits on jet fragment production may be determined. The same method may be extended to A-A collisions where the role of minimum-bias jets in spectra and correlations is strongly contested.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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HERAFitter - an open source QCD fit framework
Title
HERAFitter - an open source QCD fit framework, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator
Starovitov, Pavel
Date
2013-09-15, 2013-09-15
Publisher
IIT Press
Description
The patron distribution functions (PDFs) describe the parton content of the proton. They cannot be calculated from the first principle and are...
Show moreThe patron distribution functions (PDFs) describe the parton content of the proton. They cannot be calculated from the first principle and are to be determined empirically by fitting experimental observables to quantum chromodynamics (QCD) predictions. The HERAFitter project aims to provide a framework for QCD analyses of proton structure at leading order (LO), next-to-leading order (NLO) and next-to-next-to-leading (NNLO) orders in perturbative QCD. The framework includes various modules and interfaces enabling a large number of theoretical and methodological options. It also allows to study the impact of the new experimental data on the PDFs from ep, pp and pp̅ scattering processes. The fast development of the project involves active communication with theorists and experimentalist as well as a close collaboration with the main PDF fitting groups. Full information about the project, downloads and documentation can be found in http://herafitter.org.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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Collective dynamics of the p-Pb collisions at the LHC
Title
Collective dynamics of the p-Pb collisions at the LHC, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator
Broniowski, Wojciech, Bożek, Piotr
Date
2013-09-15, 2013-09-15
Publisher
IIT Press
Description
We review the signatures for the soft collective dynamics in highest-multiplicity ultrarelativistic p-Pb collisions and show that the effects...
Show moreWe review the signatures for the soft collective dynamics in highest-multiplicity ultrarelativistic p-Pb collisions and show that the effects are well described in a three-stage model, consisting of the event-by-event Glauber initial conditions, viscous 3+1D hydrodynamics, and statistical hadronization. In particular, we discuss the ridges in two-particle correla- tions in the relative azimuth and pseudorapidity, the elliptic and triangular flow coefficients, and the mass hierarchy of observables sensitive to flow.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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Recent Results from RHIC
Title
Recent Results from RHIC, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator
Evdokimov, O.
Date
2013-09-15, 2013-09-15
Publisher
IIT Press
Description
The Relativistic Heavy Ion Collider (RHIC) has opened a new era in experimental nuclear physics. Among the most important discoveries of this...
Show moreThe Relativistic Heavy Ion Collider (RHIC) has opened a new era in experimental nuclear physics. Among the most important discoveries of this new era are the jet quenching phenomenon, the energy loss suffered by a hard scattered parton traversing the medium, and the collective flow, approaching the limit of ideal hydrodynamics. RHIC experiments have introduced a number of novel correlation methods for studies of jets and jet-medium interactions in the high multiplicity environment of ultra-relativistic heavy ion collisions. The di- and multi-hadron correlation techniques have since been quintessential to the understanding of the properties of the created medium in many complementary ways. In this work selected recent results are presented for the RHIC’s top energy collisions at 200 GeV. Di-hadron correlation measurements from Au–Au collisions, illuminating the properties of the hot nuclear medium, are confronted with the recent findings from d–Au data at the same energy. Understanding of initial state properties and collision evolution is tested by unexpected similarities in the di-hadron correlation measurements between the two systems.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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BSM searches in multi-objects final states in ATLAS
Title
BSM searches in multi-objects final states in ATLAS, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator
Cornelissen, Thijs
Date
2013-09-15, 2013-09-15
Publisher
IIT Press
Description
Recent results on searches for new physics from Run 1 of the Large Hadron Collider are reported. The ATLAS experiment has already collected...
Show moreRecent results on searches for new physics from Run 1 of the Large Hadron Collider are reported. The ATLAS experiment has already collected more than 20 fb−1 of integrated luminosity, allowing for a large number of new phenomena searches in many different final states. No deviations from the Standard Model expectations are found, and corresponding constraints on physics beyond the Standard Model are obtained.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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