Charm quark mass with calibrated uncertainty

2016

We determine the charm quark mass ${\hat m}_c({\hat m}_c)$ from QCD sum rules of moments of the vector current correlator calculated in perturbative QCD. Only experimental data for the charm resonances below the continuum threshold are needed in our approach, while the continuum contribution is determined by requiring self-consistency between various sum rules, including the one for the zeroth moment. Existing data from the continuum region can then be used to bound the theoretical error. Our result is ${\hat m}_c({\hat m}_c) = 1272 \pm 8$ MeV for $\hat\alpha_s(M_Z) = 0.1182$. Special attention is given to the question how to quantify and justify the uncertainty.

Photon plus jet cross sections in deep inelastic ep collisions at order O(α2αs)

2000

The production of a hard and isolated photon accompanied by one or two jets in large- Q2 deep inelastic ep scattering is calculated at next-to-leading order. We include consistently contributions from quark-to-photon fragmentation and study various differential cross sections and their dependence on isolation cut parameters. Numerical results relevant for HERA experiments are presented.

Photon Plus Jet Production in Large-Q2 ep Collisions at Next-to-Leading Order QCD

1999

The production of photons accompanied by jets in large-Q2 deep inelastic ep scattering is calculated in next-to-leading order. We describe how to consistently include contributions from quark-to-photon fragmentation and give numerical results relevant for HERA experiments.

Prospects for charged current deep-inelastic scattering off polarized nucleons at a future electron-ion collider

2013

We present a detailed phenomenological study of charged-current-mediated deep-inelastic scattering off longitudinally polarized nucleons at a future Electron-Ion Collider. A new version of the event generator package DJANGOH, extended by capabilities to handle processes with polarized nucleons, is introduced and used to simulate charged current deep-inelastic scattering including QED, QCD, and electroweak radiative effects. We carefully explore the range of validity and the accuracy of the Jacquet-Blondel method to reconstruct the relevant kinematic variables from the measured hadronic final state in charged current events, assuming realistic detector performance parameters. Finally, we est…

Simultaneous extraction of fragmentation functions of light charged hadrons with mass corrections

2021

Achieving the highest possible precision for theoretical predictions at the present and future high-energy lepton and hadron colliders requires a precise determination of fragmentation functions (FFs) of light and heavy charged hadrons from a global QCD analysis with great accuracy. We describe a simultaneous determination of unpolarized FFs of charged pions, charged kaons and protons/antiprotons from single-inclusive hadron production in electron-positron annihilation (SIA) data at next-to-leading order and next-to-next-to-leading order accuracy in perturbative QCD. A new set of FFs, called {\tt SGKS20}, is presented. We include data for identified light charged hadrons ($\pi^\pm, K^\pm$ a…

Standard model large-ETprocesses and searches for new physics at HERA

1999

Existing and missing calculations of standard model processes producing large transverse energy in electron-proton interactions at HERA are reviewed. The adequacy of the existing standard model Monte Carlo programs for generic searches of exotic processes is analyzed.

AN OPERATOR PRODUCT EXPANSION ANALYSIS OF e+e-ANNIHILATION DATA

2013

Perturbative Quantum Chromodynamics combined with the operator product expansion is expected to provide a framework for the description of phenomena in hadron interactions including contributions of nonperturbative origin. Applied to the correlator of two electromagnetic currents, this framework can be confronted with e+e-annihilation into hadrons. Data from the total hadronic e+e-cross-section have become much more precise in recent years and the power corrections in the operator product expansion, i.e. the vacuum condensates are expected to be determined with higher precision than previously. We present an analysis of the condensates of dimensions d = 2, 4 and 6 and find reasonably stable…

High $p_{T}$ Leptons and W Production at HERA

1999

Details are given of the observation by H1 of events containing high P_T leptons in addition to large missing P_T. A closely related ZEUS analysis, including a preliminary measurement of the W production cross section, is discussed and the two experiments are compared. Some possible non-Standard Model sources for the events are considered.

Inclusive D∗-meson production in ep scattering at low Q2 in the GM-VFN scheme at NLO

2009

Abstract We have calculated the next-to-leading order cross sections for the inclusive production of D ∗ -mesons in ep collisions at HERA for finite, although very small Q 2 . In this Q 2 -range, the same approximations as for photoproduction can be used. Our calculation is performed in the general-mass variable-flavour-number scheme. In this approach, large logarithms of the charm transverse momentum are resummed and finite terms depending on m 2 / p T 2 are kept in the hard scattering cross sections. The theoretical results are compared with recent data from the ZEUS Collaboration at HERA. On average, we find good agreement.

Theoretical determination of the hadronic (g-2) of the muon

2016

An approach is discussed on the determination of the leading order hadronic contribution to the muon anomaly, $a_\mu^{HAD}$, based entirely on theory. This method makes no use of $e^+ e^-$ annihilation data, a likely source of the current discrepancy between theory and experiment beyond the $3\, \sigma$ level. What this method requires is essentially knowledge of the first derivative of the vector current correlator at zero-momentum. In the heavy-quark sector this is obtained from the well known heavy quark expansion in perturbative QCD, leading to values of $a_\mu^{HAD}$ in the charm- and bottom-quark region which were fully confirmed by later lattice QCD (LQCD) results. In the light-quark…

Weak charge and weak radius of C12

2020

We present a feasibility study of a simultaneous subpercent extraction of the weak charge and the weak radius of the $^{12}\mathrm{C}$ nucleus using parity-violating electron scattering, based on a largely model-independent assessment of the uncertainties. The corresponding measurement is considered to be carried out at the future MESA facility in Mainz with ${E}_{\mathrm{beam}}=155\phantom{\rule{0.28em}{0ex}}\mathrm{MeV}$. We find that a combination of a 0.3% precise measurement of the parity-violating asymmetry at forward angles with a 10% measurement at backward angles will allow to determine the weak charge and the weak radius of $^{12}\mathrm{C}$ with 0.4% and 0.5% precision, respectiv…

New physics constraints from atomic parity violation in Cs133

2021

Our improved calculation of the nuclear spin-independent parity violating electric dipole transition amplitude ($E{1}_{\mathrm{PV}}$) for $6s{^{2}S}_{1/2}\ensuremath{-}7s{^{2}S}_{1/2}$ in $^{133}\mathrm{Cs}$ in combination with the most accurate (0.3%) measurement of this quantity yields a new value for the nuclear weak charge ${Q}_{W}=\ensuremath{-}73.71(26{)}_{ex}(23{)}_{th}$ against the Standard Model (SM) prediction ${Q}_{W}^{\mathrm{SM}}=\ensuremath{-}73.23(1)$. The advances in our calculation of $E{1}_{\mathrm{PV}}$ have been achieved by using a variant of the perturbed relativistic coupled-cluster theory, which treats the contributions of the core, valence, and excited states to $E{1…

Nuclear parton distribution functions with uncertainties in a general mass variable flavor number scheme

2020

In this article we obtain a new set of nuclear parton distribution functions (nuclear PDFs) at next-to-leading order and next-to-next-to-leading order accuracy in perturbative QCD. The common nuclear deep-inelastic scattering (DIS) data analyzed in our study are complemented by the available charged-current neutrino DIS data with nuclear targets and data from Drell-Yan cross-section measurements for several nuclear targets. In addition, the most recent DIS data from the Jefferson Lab CLAS and Hall C experiments are also added to our data sample. For these specific datasets, we consider the impact of target mass corrections and higher twist effects which are expected to be important in the r…

Higgs CP properties using the tau decay modes at the ILC

2013

We investigate the prospects of determining the CP nature of the 126 GeV neutral spin-0 (Higgs) boson h, discovered at the LHC, at a future linear collider. We consider the production of h by the Higgsstrahlung process and its subsequent decays to tau leptons. We investigate how precisely a possible pseudoscalar component of h can be detected by the measurement of a suitably defined angular distribution, if all major decay modes of the tau lepton are used. From our numerical simulations, we estimate the expected precision to the scalar-pseudoscalar mixing angle, including estimates of the background and of measurement uncertainties, to be 2.8 degree for Higgs-boson production at a center-of…

Conductivity imaging with interior potential measurements

2011

In this article, we present two reconstruction methods intended to be used for conductivity imaging with data obtained from a planar electrical impedance tomography device for breast cancer detection. The inverse problem to solve is different from the classical inverse conductivity problem. We reconstruct the electrical conductivity of a two-dimensional domain from boundary measurements of currents and interior measurements of the potential. One reconstruction algorithm is based on a discrete resistor model; the other one is an integral equation approach for smooth conductivity distributions.

Finite-Mass Effects on Inclusive B-Meson Hadroproduction

2007

We calculate the transverse-momentum (p_T) distribution for the inclusive hadroproduction of B mesons at intermediate values of p_T at next-to-leading order (NLO) in a dedicated finite-mass scheme using realistic non-perturbative fragmentation functions that are obtained through a global fit to e^+e^- data from CERN LEP1 and SLAC SLC exploiting their universality and scaling violations. We find that finite-mass effects moderately enhance the cross section, by about 20% at p_T = 2 m_b, and rapidly fade out with increasing value of p_T, so that the zero-mass prediction is reached. We also perform comparisons with recent ppbar data taken by the CDF Collaboration in run II at the Fermilab Tevat…

Contact Interactions with Polarized Beams at HERA

1998

The discovery potential of the HERA collider, with and without polarized beams, for electron-quark contact interactions in neutral current scattering is reviewed. The measurement of spin asymmetries in the polarized case could give crucial information on the chiral structure of new interactions.

Inclusive D* production in gamma-gamma collisions: including the single-resolved contribution with massive quarks

2003

We have calculated the next-to-leading order cross section for the inclusive production of charm quarks as a function of the transverse momentum p_T and the rapidity in two approaches using massive or massless charm quarks. For the single-resolved cross section we have derived the massless limit from the massive theory. We find that this limit differs from the genuine massless version with MS-bar factorization by finite corrections. By adjusting subtraction terms we establish a massive theory with MS-bar subtraction which approaches the massless theory very fast with increasing transverse momentum. With these results and including the equivalent results for the direct cross section obtained…

QCD condensates from tau-decay data: A functional approach

2004

We study a functional method to extract the V − A condensate of dimension 6 from a comparison of τ -decay data with the asymptotic space-like QCD prediction. Our result is in agreement within errors with that from conventional analyses based on finite energy sum rules.

Chiral sum rules and vacuum condensates from tau-lepton decay data

2015

QCD finite energy sum rules, together with the latest updated ALEPH data on hadronic decays of the tau-lepton are used in order to determine the vacuum condensates of dimension $d=2$ and $d=4$. These data are also used to check the validity of the Weinberg sum rules, and to determine the chiral condensates of dimension $d=6$ and $d=8$, as well as the chiral correlator at zero momentum, proportional to the counter term of the ${\cal{O}}(p^4)$ Lagrangian of chiral perturbation theory, $\bar{L}_{10}$. Suitable (pinched) integration kernels are introduced in the sum rules in order to suppress potential quark-hadron duality violations. We find no compelling indications of duality violations in t…

Beyond the Standard Model at HERA

2007

The prospects of physics beyond the standard model in deep inelastic scattering are reviewed, emphasizing the search for contact interactions, for leptoquarks and for supersymmetry with R-parity violation, R-parity violating supersymmetry is explored as a speculative source of events with high energy muons and missing transverse momentum, but no convincing explanation for events of this type observed at HI is found.

Reconciling open charm production at the Fermilab Tevatron with QCD

2005

We study the inclusive hadrodroduction of D^0, D^+, D^{*+}, and D_s^+ mesons at next-to-leading order in the parton model of quantum chromodynamics endowed with universal non-perturbative fragmentation functions (FFs) fitted to e^+e^- annihilation data from CERN LEP1. Working in the general-mass variable-flavor-number scheme, we resum the large logarithms through the evolution of the FFs and, at the same time, retain the full dependence on the charm-quark mass without additional theoretical assumptions. In this way, the cross section distributions in transverse momentum recently measured by the CDF Collaboration in run II at the Fermilab Tevatron are described within errors.

QCD condensates of dimension D=6 and D=8 from hadronic τ-decays

2007

Abstract The high-precision data from hadronic τ decays allows one to extract information on QCD condensates. Using the finalized ALEPH data, we obtain a more rigorous determination of the dimension 6 and 8 condensates for the ( V − A ) correlator. In particular, we find that the recent data fix a certain linear combination of these QCD condensates to a precision at the level of O(2)%. Our approach relies on more general assumptions than alternative approaches based on finite energy sum rules.

Conductivity reconstructions using real data from a new planar electrical impedance tomography device

2013

Abstract In this paper, we present results of reconstructions using real data from a new planar electrical impedance tomography device developed at the Institut fur Physik, Johannes Gutenberg Universitat, Mainz, Germany. The prototype consists of a planar sensing head of circular geometry, and it was designed mainly for breast cancer detection. There are 12 large outer electrodes arranged on a ring of radius  cm where the external currents are injected, and a set of 54 point-like high-impedance inner electrodes where the induced voltages are measured. Two direct (i.e. non-iterative) reconstruction algorithms are considered: one is based on a discrete resistor model, and the other one is an …

How to pin down theCPquantum numbers of a Higgs boson in itsτdecays at the LHC

2011

We investigate how the $CP$ quantum numbers of a neutral Higgs boson or spin-zero resonance $\ensuremath{\Phi}$, produced at the CERN Large Hadron Collider, can be determined in its $\ensuremath{\tau}$-pair decay mode $\ensuremath{\Phi}\ensuremath{\rightarrow}{\ensuremath{\tau}}^{\ensuremath{-}}{\ensuremath{\tau}}^{+}$. We use a method [S. Berge and W. Bernreuther, Phys. Lett. B 671, 470 (2009).] based on the distributions of two angles and apply it to the major 1-prong $\ensuremath{\tau}$ decays. We show for the resulting dilepton, lepton-pion, and two-pion final states that appropriate selection cuts significantly enhance the discriminating power of these observables. From our analysis we…

Inclusive D* Production in Photon-Photon Collisions at Next-to-Leading Order QCD

2001

The next-to-leading order cross section for the inclusive production of charm quarks in gamma-gamma collisions is calculated as a function of the transverse momentum pT and the rapidity y in approaches using massive or massless charm quarks. For the direct cross section we derive the massless limit from the massive theory with the result that this limit differs from the massless version with MSbar factorization by finite corrections. Subtracting or adding these corrections allows us to compare the two approaches on equal footing. We establish massless and massive versions with 3 and 4 initial flavours which are shown to approach the massless approximations very fast with increasing pT. With…

Open charm hadroproduction and the charm content of the proton

2009

We advocate charmed-hadron inclusive hadroproduction as a laboratory to probe intrinsic charm (IC) inside the colliding hadrons. Working at next-to-leading order in the general-mass variable-flavor-number scheme endowed with non-perturbative fragmentation functions recently extracted from a global fit to e^+e^- annihilation data from KEKB, CESR, and LEP1, we first assess the sensitivity of Tevatron data of D^0, D^+, and D^{*+} inclusive production to the IC parameterizations provided by Pumplin et al. We then argue that similar data from pp collisions at RHIC would have the potential to discriminate between different IC models provided they reach out to sufficiently large values of transver…

Λc± production in pp collisions with a new fragmentation function

2020

We study inclusive ${\mathrm{\ensuremath{\Lambda}}}_{c}^{\ifmmode\pm\else\textpm\fi{}}$-baryon production in $pp$ collisions in the general-mass variable-flavor-number scheme and compare with data from the LHCb, ALICE, and CMS collaborations. We perform a new fit of the $c\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Lambda}}}_{c}^{+}$ fragmentation function combining ${e}^{+}{e}^{\ensuremath{-}}$ data from OPAL and Belle. The agreement with LHC data is slightly worse compared with a calculation using an older fragmentation function, and the tension between different determinations of ${\mathrm{\ensuremath{\Lambda}}}_{c}^{\ifmmode\pm\else\textpm\fi{}}$ production cross sections from the LHC…

Beam-normal single-spin asymmetry in elastic scattering of electrons from a spin-0 nucleus

2021

We study the beam-normal single-spin asymmetry (BNSSA) in high-energy elastic electron scattering from several spin-0 nuclei. Existing theoretical approaches work in the plane-wave formalism and predict the BNSSA to scale as $\ensuremath{\sim}A/Z$ with the atomic number $Z$ and nuclear mass number $A$. While this prediction holds for light and intermediate nuclei, a striking disagreement in both the sign and the magnitude of BNSSA was observed by the PREX collaboration for $^{208}\mathrm{Pb}$, coined the ``PREX puzzle.'' To shed light on this disagreement, we go beyond the plane-wave approach which neglects Coulomb distortions known to be significant for heavy nuclei. We explicitly investig…

Inclusive D* -Meson Photoproduction in the GM-VFNS

2009

Gluon fragmentation to gluonium

2000

The fragmentation of gluons to gluonium states is analyzed qualitatively in the non-perturbative region. The convolution of this mechanism with perturbative gluon radiation leaves us with a hard component in the fragmentation of gluon to gluonium.

Charm quark mass determined from a pair of sum rules

2016

In this paper, we present preliminary results of the determination of the charm quark mass $\hat{m}_c$ from QCD sum rules of moments of the vector current correlator calculated in perturbative QCD at ${\cal O} (\hat \alpha_s^3)$. Self-consistency between two different sum rules allow to determine the continuum contribution to the moments without requiring experimental input, except for the charm resonances below the continuum threshold. The existing experimental data from the continuum region is used, then, to confront the theoretical determination and reassess the theoretic uncertainty.

The Standard Model

2002

Publisher Summary The weak interactions of the elementary particles are discovered in β-decay processes. They are described by an effective Lagrangian of current × current type in which the weak currents are coherent superpositions of charged vector and axial-vector currents, accounting for the violation of parity. The Fermi theory of the weak interactions can only be interpreted as an effective low-energy theory that cannot be extended to arbitrarily high energies. Applying this theory to the scattering process at high energies, the scattering amplitude rises indefinitely with the square of the energy. The structure of the electroweak system that has emerged from the requirement of asympto…

Reduced uncertainty of the axial $\gamma Z$-box correction to the proton's weak charge

2019

We present the fully up-to-date calculation of the $\gamma Z$-box correction which needs to be taken into account to determine the weak mixing angle at low energies from parity-violating electron proton scattering. We make use of neutrino and antineutrino inclusive scattering data to predict the parity-violating structure function $F_3^{\gamma Z}$ by isospin symmetry. Our new analysis confirms previous results for the axial contribution to the $\gamma Z$-box graph, and reduces the uncertainty by a factor of~2. In addition, we note that the presence of parity-violating photon-hadron interactions induces an additional contribution via $F_3^{\gamma \gamma}$. Using experimental and theoretical …

Weak charge and weak radius of ${}^{12}$C

2020

We present a feasibility study of a simultaneous sub-percent extraction of the weak charge and the weak radius of the ${}^{12}$C nucleus using parity-violating electron scattering, based on a largely model-independent assessment of the uncertainties. The corresponding measurement is considered to be carried out at the future MESA facility in Mainz with $E_{\rm beam} = 155$ MeV. We find that a combination of a $0.3\%$ precise measurement of the parity-violating asymmetry at forward angles with a $10\%$ measurement at backward angles will allow to determine the weak charge and the weak radius of ${}^{12}$C with $0.4\%$ and $0.5\%$ precision, respectively. These values could be improved to $0.…