How to precisely measure the W boson properties - the most recent ATLAS results

<!--HTML--><p class="MsoNormal"><span style="font-family:&quot;Calibri&quot;,sans-serif;font-size:11.0pt;mso-ansi-language:EN-GB;mso-bidi-language:AR-SA;mso-fareast-font-family:&quot;Times New Roman&quot;;mso-fareast-language:EN-GB;">The Standard Model is the most powerful theory describing the fundamental constituents of matter and their interactions. Historically, relations between the fundamental&nbsp;parameters of the SM have been used to predict the mass of the top quark and to put constraints on the Higgs boson mass before these particles were experimentally&nbsp;confirmed. Today, the indirect determination of the W-boson mass from global electroweak fits outperforms the precision of its experimentally measured value. An improved&nbsp;experimental measurement is, therefore, one of the goals of the LHC physics program, aiming to test the overall consistency of the Standard Model and possibly reveal new,&nbsp;conflicting phenomena.</span><br><br><span style="font-family:&quot;Calibri&quot;,sans-serif;font-size:11.0pt;mso-ansi-language:EN-GB;mso-bidi-language:AR-SA;mso-fareast-font-family:&quot;Times New Roman&quot;;mso-fareast-language:EN-GB;">The seminar will discuss the improved measurement of the mass of the W boson at a centre-of-mass energy of 7 TeV, recently released by the ATLAS Collaboration. The&nbsp;previous ATLAS measurement is re-evaluated using a profile likelihood fit, which improves the precision of the mass determination by 15% by fully exploiting the information&nbsp;present in data.</span><br><br><span style="font-family:&quot;Calibri&quot;,sans-serif;font-size:11.0pt;mso-ansi-language:EN-GB;mso-bidi-language:AR-SA;mso-fareast-font-family:&quot;Times New Roman&quot;;mso-fareast-language:EN-GB;">Further improvements of the mass measurements are challenging and the modelling of the W-boson production and decay is one of the limiting factors to ultimately reach an&nbsp;uncertainty of 10 MeV at the LHC. New ATLAS measurements of the W and Z boson transverse momenta at a 5 and 13 TeV will also be presented. This remarkable analysis&nbsp;is performed using dedicated LHC runs with reduced instantaneous luminosity. Such an experimental environment is favourable for the reconstruction of the W-boson&nbsp;transverse momentum from the hadronic recoil. A high resolution of the hadronic recoil allows the low transverse momentum of the W boson to be measured with&nbsp;unprecedented granularity. The measurement provides a fundamental input for reducing the physics-modelling uncertainties in future W-boson mass determinations.</span></p><p class="MsoNormal"><strong>Refreshments will be served at 10:30</strong></p>