Search results for "Collider"
showing 10 items of 1690 documents
Measuring KS0K± interactions using Pb–Pb collisions at sNN=2.76 TeV
2019
We present the first measurements of femtoscopic correlations between the KS0 and K± particles in pp collisions at s=7 TeV measured by the ALICE experiment. The observed femtoscopic correlations are consistent with final-state interactions proceeding solely via the a0(980) resonance. The extracted kaon source radius and correlation strength parameters for KS0K− are found to be equal within the experimental uncertainties to those for KS0K+ . Results of the present study are compared with those from identical-kaon femtoscopic studies also performed with pp collisions at s=7 TeV by ALICE and with a KS0K± measurement in Pb–Pb collisions at sNN=2.76 TeV. Combined with the Pb–Pb results, our pp a…
W+W−Production at Hadron Colliders in Next to Next to Leading Order QCD
2014
Charged gauge boson pair production at the Large Hadron Collider allows detailed probes of the fundamental structure of electroweak interactions. We present precise theoretical predictions for on-shell W+ W- production that include, for the first time, QCD effects up to next to next to leading order in perturbation theory. As compared to next to leading order, the inclusive W+ W- cross section is enhanced by 9% at 7 TeV and 12% at 14 TeV. The residual perturbative uncertainty is at the 3% level. The severe contamination of the W+ W- cross section due to top-quark resonances is discussed in detail. Comparing different definitions of top-free W+ W- production in the four and five flavor numbe…
Large Effects from Small QCD Instantons: Making Soft Bombs at Hadron Colliders
2020
It is a common belief that the last missing piece of the Standard Model of particles physics was found with the discovery of the Higgs boson at the Large Hadron Collider. However, there remains a major prediction of quantum tunnelling processes mediated by instanton solutions in the Yang-Mills theory, that is still untested in the Standard Model. The direct experimental observation of instanton-induced processes, which are a consequence of the non-trivial vacuum structure of the Standard Model and of quantum tunnelling in QFT, would be a major breakthrough in modern particle physics. In this paper, we present for the first time a full calculation of QCD instanton-induced processes in proton…
Results from pQCD for A+A collisions at RHIC & LHC energies
2000
This talk will discuss how to compute initial quantites in heavy ion collisions at RHIC (200 AGeV) and at LHC (5500 AGeV) using perturbative QCD (pQCD) by including the next-to-leading order (NLO) corrections and a dynamical determination of the dominant physical scale. The initial numbers are converted into final ones by assuming kinetic thermalization and adiabatic expansion.
Measurement of ϒ(1S) Elliptic Flow at Forward Rapidity in Pb-Pb Collisions at sNN=5.02 TeV
2019
The first measurement of the Υ(1S) elliptic flow coefficient (v2) is performed at forward rapidity (2.5 < y < 4) in Pb–Pb collisions at √sNN=5.02 TeV with the ALICE detector at the LHC. The results are obtained with the scalar product method and are reported as a function of transverse momentum (pT) up to 15 GeV/c in the 5%–60% centrality interval. The measured Υ(1S)v2 is consistent with 0 and with the small positive values predicted by transport models within uncertainties. The v2 coefficient in 2 < pT < 15 GeV/c is lower than that of inclusive J/ψ mesons in the same pT interval by 2.6 standard deviations. These results, combined with earlier suppression measurements, are in agreement with…
Small-x physics at the LHeC
2018
The Large Hadron-electron Collider LHeC is a proposed upgrade of the LHC. It would add an electron beam to the LHC, and make it possible to study electron-proton and electron-nucleus collisions at very high energies. We present some of the highlights of the LHeC physics program related to the studies of partonic structure of protons and nuclei, and to the non-linear QCD phenomena visible at small $x$.
Experimental study ofψ′decays toK+K−π0andK+K−η
2012
Using (106 +/- 4) x 10(6) psi ' events accumulated with the BESIII detector at the BEPCII e(+)e(-) collider, we present measurements of the branching fractions for psi' decays to K+K- pi(0) and K+K- eta. In these final states, the decay psi' -> K-2(*) (1430)(+) K- + 10(-5), is observed for the first time, and its branching fraction is measured to be (7.12 +/- 0: 62(stat)(-0.61)(+1.13) (syst)) x 10(-5), which indicates a violation of the helicity selection rule in psi' decays. The branching fractions of psi' -> K* (892)(+) K- + c.c., phi eta, and phi pi(0) are also measured. The measurements are used to test the QCD predictions on charmonium decays.
The ridge in proton-proton collisions at the LHC
2010
We show that the key features of the CMS result on the ridge correlation seen for high multiplicity events in sqrt(s)=7TeV proton-proton collisions at the LHC can be understood in the Color Glass Condensate framework of high energy QCD. The same formalism underlies the explanation of the ridge events seen in A+A collisions at RHIC, albeit it is likely that flow effects may enhance the magnitude of the signal in the latter.
Measurements of mixed harmonic cumulants in Pb–Pb collisions at sNN=5.02 TeV
2021
Correlations between moments of different flow coefficients are measured in Pb–Pb collisions at sNN=5.02 TeV recorded with the ALICE detector. These new measurements are based on multiparticle mixed harmonic cumulants calculated using charged particles in the pseudorapidity region |η|<0.8 with the transverse momentum range 0.2<pT<5.0 GeV/c. The centrality dependence of correlations between two flow coefficients as well as the correlations between three flow coefficients, both in terms of their second moments, are shown. In addition, a collection of mixed harmonic cumulants involving higher moments of v2 and v3 is measured for the first time, where the characteristic signature of ne…
Explaining 750 GeV diphoton excess from top/bottom partner cascade decay in two-Higgs-doublet model extension
2016
In this paper, we interpret the 750 GeV diphoton excess in the Zee-Babu extension of the two-Higgs-doublet model by introducing a top partner ($T$)/bottom partner ($B$). In the alignment limit, the 750 GeV resonance is identified as the heavy CP-even Higgs boson ($H$), which can be sizably produced via the QCD process $pp \to T\bar{T}$ or $pp \to B\bar{B}$ followed by the decay $T\to Ht$ or $B \to Hb$. The diphoton decay rate of $H$ is greatly enhanced by the charged singlet scalars predicted in the Zee-Babu extension and the total width of $H$ can be as large as 7 GeV. Under the current LHC constraints, we scan the parameter space and find that such an extension can account for the observe…