Measurement of Higgs decay to WW* in Higgsstrahlung at s\sqrt{s}=500 GeV ILC and in WW-fusion at s\sqrt{s}=3 TeV CLIC

This talk presents results of the two independent analyses evaluating the measurement accuracy of the branching ratio for the Standard model Higgs boson decay to a W-pair, at the Compact Linear Collider (CLIC) and at the International Linear Collider (ILC). The considered Higgs production channels are the WW-fusion for the highest energy stage of CLIC, $\sqrt{s}$= 3 TeV, and the Higgsstrahlung process for the nominal ILC energy, $\sqrt{s}$=500 GeV. Both studies are performed using the full simulation of the detector. The realistic experimental conditions have been simulated including beam energy spectrum, initial state radiation and the backround from $\gamma\gamma\rightarrow hadrons$ processes, which are overlaid on simulated events. The multivariate analysis technique is used for the final event selection and the expected relative statistical uncertainty, $\Delta (\sigma \cdot BR) / (\sigma\cdot BR)$, of the measured Higgs production cross sections is estimated.Comment: 7 pages, 3 figures Talk presented at the International Workshop on Future Linear Colliders (LCWS16), Morioka, Japan, 6-10 December 2016. C16-12-05.

Radon background in rare event searches at DARWIN experiment

One of the most intriguing questions of new physics is the possible existence of, so called, “dark” or “missing” matter. One of the possible candidate for the cold dark matter, is the weakly interacting massive particle (WIMP) which is investigated using several types of experiments. Among many, the direct detection liquid noble gasses experiments are the leading ones in terms of sensitivity to >GeV WIMP mass parameter space. The foreseen future European astroparticle observatory, DARWIN, is designed as an ultimate direct detection liquid xenon based experiment in dark matter searches. DARWIN’s rich experimental program of also includes other rare event searches, such as an investigation of the Majorana nature of neutrinos though neutrinoless double beta decay, the search for the axion, a hypothetical particle proposed as a solution of the strong CP problem or many others. Rare event searches, besides large scale detectors with low detection threshold, require high control and almost background free environment. Two types of background processes can mimic the WIMP recoil signal, nuclear and electronic recoil events. The dominant electronic recoil background is coming from the radon progenies (Rn222). Since it is created by radioactive decay inside all detector materials, the effective detector shielding is hindered. Here we present the requirements of radon level in xenon target necessary to reach the foreseen sensitivity in rare event searches. We also give the state-of-the-art of radon mitigation strategies which include material selection and screening, on-line radon removal techniques, as well as the off-line methods of tagging electronic recoil events from radon progenies.RAD 2023 : 11th International Conference on Radiation Natural Sciences, Medicine, Engineering, Technology and Ecology (RAD 2023) 19–23.06.2023; Herceg Novi, Montenegr

Measurement of Higgs to WW in the all-jet final state at CEPC vs=250 GeV

The most important pillar in the physics case of future electron-positron colliders in high energy physics is the measurement of the Higgs boson, with its main goal to precisely measure its properties and to probe potential of associated new physics. All next generation electron positron facilities in high energy physics will make use of the Higgsstrahlung Higgs production channel. The physics potential of CEPC for measurement of the cross-section times branching ratio of subdominant decay H ? WW* is presented. The Higgsstrahnlung Higgs production channel is used, at the center of mass energy of 250 GeV. The fully hadronic decay, containing six soft-jets in the final state is of great importance for the detector design, jet pairing and reconstruction as showing the capability of CEPC for W/Z separation. The analysis is performed in full simulation. © Copyright owned by the author(s) under the terms of the Creative Common

Systematic effects in luminosity measurement at ILC

In order to achieve required precision of luminosity measurement at the International Linear Collider (ILC), that is of order of 10-4, systematic effects have to be understood at the level of this precision. Apart from systematic effects originating from hardware design and precision of the detector alignment, physics processes also contribute either as a background or additional interaction effects. Properties of physics background, its separation from the Bhabha signal, as well as the influence of selection criteria on the overall systematics of the measurement have been studied

Measurement of the Higgs decay to electroweak bosons at low and intermediate CLIC energies

In this paper a simulation of measurements of the Higgs boson decay to electroweak bosons in $e^+e^-$ collisions at CLIC is presented. Higgs boson production and subsequent $H\rightarrow ZZ^\ast$ and $H\rightarrow WW^\ast$ decay processes were simulated alongside the relevant background processes at 350 GeV and 1.4 TeV center-of-mass energy. Full detector simulation and event reconstruction were used under realistic beam conditions. The achievable statistical precision of the measured product of the Higgs production cross section and the branching ratio for the analysed decays has been determined.Comment: Talk presented at International Workshop on Future Linear Colliders (LCWS15), Whistler, Canada, 2-6 November 2015, CLICdp-Conf-2016-00

Events with an isolated lepton and missing transverse momentum and measurement of W production at HERA

A search for events containing an isolated electron or muon and missing trans verse momentum produced in e(+/-)p collisions is performed with the H1 and ZEUS detectors at HERA. The data were taken in the period 1994-2007 and correspond to an integrated luminosity of 0.98 fb(-1). The observed event yields are in good overall agreement with the Standard Model prediction, which is dominated by single W production. In the e(+)p data, at large hadronic transverse momentum P-T(X) GT 25GeV, a total of 23 events are observed compared to a prediction of 14.0 +/- 1.9. The total single W boson production cross section is measured as 1.06 +/- 0.16 (stat.) +/- 0.07 (sys.) pb, in agreement with an Standard Model (SM) expectation of 1.26 +/- 0.19 pb

Jet production in ep collisions at low Q(2) and determination of alpha(s)

The production of jets is studied in deep-inelastic e(+) p scattering at low negative four momentum transfer squared 5 LT Q(2) LT 100 GeV2 and at inelasticity 0.2 LT y LT 0.7 using data recorded by the H1 detector at HERA in the years 1999 and 2000, corresponding to an integrated luminosity of 43.5 pb(-1). Inclusive jet, 2-jet and 3-jet cross sections as well as the ratio of 3-jet to 2-jet cross sections are measured as a function of Q(2) and jet transverse momentum. The 2-jet cross section is also measured as a function of the proton momentum fraction xi. The measurements are well described by perturbative quantum chromodynamics at next-to-leading order corrected for hadronisation effects and are subsequently used to extract the strong coupling as

Erratum to: Measurement of D*(+/-) meson production and determination of F-2(c(c)over-bar) at low Q(2) in deep-inelastic scattering at HERA

Inclusive production of D* mesons in deep-inelastic ep scattering at HERA is studied in the range 5 LT Q(2) LT 100 GeV2 of the photon virtuality and 0.02 LT y LT 0.7 of the inelasticity of the scattering process. The observed phase space for the D* meson is (pT) (D*) GT 1.25 GeV and |eta( D*)| LT 1.8. The data sample corresponds to an integrated luminosity of 348 pb(-1) collected with the H1 detector. Single and double differential cross sections are measured and the charm contribution F-2(c (c) over bar) to the proton structure function F-2 is determined. The results are compared to perturbative QCD predictions at next-to-leading order implementing different schemes for the charm mass treatment and with Monte Carlo models based on leading order matrix elements with parton showers