DIS2015 Heavy Flavours Working Group Summary

Studies presented in the heavy flavours working group are summarized. Very recent results of measurements at the HERA, LHC, Tevatron, STAR, PHENIX, and BaBar experiments are reviewed and new developments in theory and phenomenology are discussed. In particular, aspects of the impact of heavy flavours on global QCD analyses to determine the structure of the proton, and analyses in physics beyond the Standard Model are considered.Comment: 16 pages, 16 figures, Conference proceeding summary, DIS2015 "The XXIII International Workshop on Deep Inelastic Scattering and Related Subjects", April 27 - May 1, 2015, Southern Methodist University, Dallas, Texas, US

A novel phenomenological approach to total charm cross section measurements at the LHC

Measuring the total charm cross section is important for the comparison to theoretical predictions of the highest precision available for charm today, which are completely known up to NNLO QCD for the total inclusive cross sections. These are also independent of charm fragmentation, while practical measurements of charm hadrons in a fiducial phase space are not. Recently the LHC experiments have reported non-universality of charm fragmentation, which shows that e.g. charm baryon-to-meson ratios are not universal in different collision systems, and that the related production fractions also depend on transverse momentum. This breaks the charm fragmentation universality that was assumed until recently for the extrapolation of experimental measurements to the full total charm cross section phase space. A proposal is made how to address this non-universality in a data driven way without the need to implement any particular non-universal fragmentation model. As a practical example, this method is applied to the extrapolation of published LHC measurements of $D^0$ production at $\sqrt{s}=5$ TeV to the corresponding total charm cross section, which fully accounts for charm fragmentation non-universality for the first time. The result, $8.43 ^{+1.05}_{-1.16}(\text{total})$ mb, differs substantially from the one assuming charm fragmentation universality, but still compares well to theoretical QCD predictions up to NNLO.Comment: to appear in Proceedings of the European Physical Society Conference on High Energy Physics (EPS-HEP2023

A determination of mc(mc) from HERA data using a matched heavy-flavor scheme

The charm quark mass is one of the fundamental parameters of the Standard Model Lagrangian. In this work we present a determination of the MSbar charm mass from a fit to the inclusive and charm HERA deep-inelastic structure function data. The analysis is performed within the xFitter framework, with structure functions computed in the FONLL general-mass scheme as implemented in APFEL. In the case of the FONLL-C scheme, we obtain mc(mc) = 1.335 +- 0.043(exp) +0.019 -0.000(param) +0.011 -0.008(mod) +0.033 -0.008(th) GeV. We also perform an analogous determination in the fixed-flavor-number scheme at next-to-leading order, finding mc(mc) = 1.318 +- 0.054(exp) +0.011 -0.010(param) +0.015 -0.019(mod) +0.045 -0.004(th) GeV, compatible with the FONLL-C value. Our results are consistent with previous determinations from DIS data as well as with the PDG world average.Comment: 37 pages, 12 figures, 3 table

Impact of heavy-flavour production cross sections measured by the LHCb experiment on parton distribution functions at low x

The impact of recent measurements of heavy-flavour production in deep inelastic $ep$ scattering and in $pp$ collisions on parton distribution functions is studied in a QCD analysis in the fixed-flavour number scheme at next-to-leading order. Differential cross sections of charm- and beauty-hadron production measured by LHCb are used together with inclusive and heavy-flavour production cross sections in deep inelastic scattering at HERA. The heavy-flavour data of the LHCb experiment impose additional constraints on the gluon and the sea-quark distributions at low partonic fractions $x$ of the proton momentum, down to $x \sim 5 \times 10^{-6}$. This kinematic range is currently not covered by other experimental data in perturbative QCD fits

Search for supersymmetry in events with b-quark jets and missing transverse energy in pp collisions at 7 TeV

Results are presented from a search for physics beyond the standard model based on events with large missing transverse energy, at least three jets, and at least one, two, or three b-quark jets. The study is performed using a sample of proton-proton collision data collected at sqrt(s) = 7 TeV with the CMS detector at the LHC in 2011. The integrated luminosity of the sample is 4.98 inverse femtobarns. The observed number of events is found to be consistent with the standard model expectation, which is evaluated using control samples in the data. The results are used to constrain cross sections for the production of supersymmetric particles decaying to b-quark-enriched final states in the context of simplified model spectra.Comment: Submitted to Physical Review

Reinterpretation of LHC Results for New Physics: Status and recommendations after Run 2

We report on the status of efforts to improve the reinterpretation of searches and measurements at the LHC in terms of models for new physics, in the context of the LHC Reinterpretation Forum. We detail current experimental offerings in direct searches for new particles, measurements, technical implementations and Open Data, and provide a set of recommendations for further improving the presentation of LHC results in order to better enable reinterpretation in the future. We also provide a brief description of existing software reinterpretation frameworks and recent global analyses of new physics that make use of the current data