Jens Erler - Academia.edu (original) (raw)
Papers by Jens Erler
Electroweak precision tests of the Standard Model of the fundamental interactions are reviewed ra... more Electroweak precision tests of the Standard Model of the fundamental interactions are reviewed ranging from the lowest to the highest energy experiments. Results from global fits are presented with particular emphasis on the extraction of fundamental parameters such as the Fermi constant, the strong coupling constant, the electroweak mixing angle, and the mass of the Higgs boson. Constraints on physics beyond the Standard Model are also discussed.
I summarize the status of the Standard Model after the 2003 summer conferences.
Future high precision electroweak measurements require understanding of Standard Model expectatio... more Future high precision electroweak measurements require understanding of Standard Model expectations to multi-loop accuracy, both, for the predictions of production cross-sections of signal and background, as well as for pseudo-observables. I review recent results from precision calculations and summarize projections and implications for the Tevatron, the LHC, CEBAF, and the ILC.
String Phenomenology 2003 - Proceedings of the 2nd International Conference, 2004
Physical Review D, 2005
We determine the weak mixing angle in the MS-scheme, sin 2θ W (µ), at energy scales µ relevant fo... more We determine the weak mixing angle in the MS-scheme, sin 2θ W (µ), at energy scales µ relevant for present and future low energy electroweak measurements. We relate the renormalization group evolution of sin 2θ W (µ) to the corresponding evolution ofα(µ) and include higher-order terms in α s and α that had not been treated in previous analyses. We also up-date the analysis of non-perturbative, hadronic contributions and argue that the associated uncertainty is small compared to anticipated experimental errors. The resulting value of the low-energy MS weak mixing angle is sin 2θ W (0) = 0.23867 ± 0.00016.
We discuss the results of a global fit to precision data in supersymmetric models. We consider bo... more We discuss the results of a global fit to precision data in supersymmetric models. We consider both gravity- and gauge-mediated models. As the superpartner spectrum becomes light, the global fit to the data typically results in larger values of chi^2. We indicate the regions of parameter space which are excluded by the data. We discuss the additional effect of the B(B --> X_s\gamma) measurement. Our analysis excludes chargino masses below MZ in the simplest gauge-mediated model with mu>0, with stronger constraints for larger values of tan beta.
We discuss the prospects for measuring the W mass and width in Run II. The basic techniques used ... more We discuss the prospects for measuring the W mass and width in Run II. The basic techniques used to measure M{sub W} are described and the statistical, theoretical and detector-related uncertainties are discussed in detail. Alternative methods of measuring the W mass at the Tevatron and the prospects for M{sub W} measurements at other colliders are also described.
Revista Mexicana De Fisica, Dec 21, 2002
I present an update on the electroweak radiative correction factor to semileptonic tau decays, in... more I present an update on the electroweak radiative correction factor to semileptonic tau decays, including a next-to-leading order resummation of large logarithms. My result differs both qualitatively and quantitatively from the one recently obtained by Davier et al. As two consequences, (i) the discrepancy between the predictions for the muon g-2 based on tau decay data and electron-positron annihilation data increases, and (ii) the g-2 prediction based on tau decay data appears to be consistent (within about one standard deviation) with the experimental result from BNL.
I review and compare various techniques to obtain the value of the QED coupling, alpha, at the Z ... more I review and compare various techniques to obtain the value of the QED coupling, alpha, at the Z pole. GigaZ precisions would require a much more accurate determination than available today. A combination of the virtues of current methods may help to achieve this goal.
Section 10 of the 2004 edition of the Review of Particle Physics.
We present a new QCD sum rule with high sensitivity to the continuum regions of charm and bottom ... more We present a new QCD sum rule with high sensitivity to the continuum regions of charm and bottom quark pair production. Combining this sum rule with existing ones yields very stable results for the msbar quark masses, m_c(m_c)$ and m_b (m_b). Comparison of our approach with experimental data allows for a robust theoretical error estimate. We have also provided a new evaluation of the lifetime of the tau lepton, serving as a strong constraint on alpha_s.
AIP Conference Proceedings, 2006
A brief review of electroweak precision data from LEP, SLC, the Tevatron, and low energies is pre... more A brief review of electroweak precision data from LEP, SLC, the Tevatron, and low energies is presented. The global fit to all data including the most recent results on the masses of the top quark and the W boson reinforces the preference for a relatively light Higgs boson. I will also give an outlook on future developments at the Tevatron Run II, CEBAF, the LHC, and the ILC.
Journal of Physics: Conference Series, 2005
The theoretical and experimental bases of neutrino mass and mixing are reviewed. A brief chronolo... more The theoretical and experimental bases of neutrino mass and mixing are reviewed. A brief chronological evolution of the weak interactions, the electroweak Standard Model, and neutrinos is presented. Dirac and Majorana mass terms are explained as well as models such as the seesaw mechanism. Schemes for two, three and four neutrino mixings are presented.
Phys Rev D, 1999
I calculate the QED coupling, alpha, directly in the MS-bar scheme using an unsubtracted dispersi... more I calculate the QED coupling, alpha, directly in the MS-bar scheme using an unsubtracted dispersion relation for the three light quarks, and perturbative QCD for charm and bottom quarks. Compact analytical expressions are presented, making this approach particularly suitable for electroweak fits. After alpha^(-1) (m_tau) = 133.513 +- 0.025 is obtained in a first step, I perform a 4-loop renormalization group evolution with 3-loop matching conditions to arrive at alpha^(-1) (M_Z) = 127.934 +- 0.026 for alpha_s (M_Z) = 0.120. The corresponding hadronic contribution to the on-shell coupling is Delta alpha_had^(5) (M_Z) = 0.02779 +- 0.00019. The error is mainly from m_c, and from experimental uncertainties in e^+ e^- annihilation into unflavored and strange hadrons and tau decay data.
Physical Review Letters, 2010
There has been renewed interest in the possibility of additional fermion generations. At the same... more There has been renewed interest in the possibility of additional fermion generations. At the same time there have been significant changes in the relevant electroweak precision constraints, in particular, in the interpretation of several of the low energy experiments. We summarize the various motivations for extra families and analyze them in view of the latest electroweak precision data.
AIP Conference Proceedings, 2006
The status in electroweak precision physics is reviewed. I present a brief summary of the latest ... more The status in electroweak precision physics is reviewed. I present a brief summary of the latest data, global fit results, a few implications for new physics, and an outlook.
Journal of Physics: Conference Series, 2005
We perform a global analysis of electroweak precision measurements to find constraints on physics... more We perform a global analysis of electroweak precision measurements to find constraints on physics beyond the Standard Model. In particular, we discuss oblique parameters, which are useful to constrain additional matter fields, as well as extra ZZZ bosons, and supersymmetry. We also summarize the present information on the Higgs boson mass.
Phys Rev Lett, 1996
In supersymmetric models with R-parity violation, scalar neutrinos may be produced as s-channel r... more In supersymmetric models with R-parity violation, scalar neutrinos may be produced as s-channel resonances in e^+e^- colliders. We note that within current constraints, the scalar neutrino may have a width of several GeV into b\bar{b} and be produced with large cross section, leading to a novel supersymmetry discovery signal at LEP II. In addition, if the scalar neutrino mass approximately equals m_Z, such a resonance necessarily increases R_b and reduces A_{FB}(b), significantly improving the fit to electroweak data. Bounds from B meson and top quark decays are leading constraints, and we stress the importance of future measurements.
Journal of Physics G Nuclear and Particle Physics, 2003
I review how electroweak precision observables can be used to constrain the Higgs boson mass and ... more I review how electroweak precision observables can be used to constrain the Higgs boson mass and the strong coupling constant. Implications for physics beyond the standard model are also addressed.
Electroweak precision tests of the Standard Model of the fundamental interactions are reviewed ra... more Electroweak precision tests of the Standard Model of the fundamental interactions are reviewed ranging from the lowest to the highest energy experiments. Results from global fits are presented with particular emphasis on the extraction of fundamental parameters such as the Fermi constant, the strong coupling constant, the electroweak mixing angle, and the mass of the Higgs boson. Constraints on physics beyond the Standard Model are also discussed.
I summarize the status of the Standard Model after the 2003 summer conferences.
Future high precision electroweak measurements require understanding of Standard Model expectatio... more Future high precision electroweak measurements require understanding of Standard Model expectations to multi-loop accuracy, both, for the predictions of production cross-sections of signal and background, as well as for pseudo-observables. I review recent results from precision calculations and summarize projections and implications for the Tevatron, the LHC, CEBAF, and the ILC.
String Phenomenology 2003 - Proceedings of the 2nd International Conference, 2004
Physical Review D, 2005
We determine the weak mixing angle in the MS-scheme, sin 2θ W (µ), at energy scales µ relevant fo... more We determine the weak mixing angle in the MS-scheme, sin 2θ W (µ), at energy scales µ relevant for present and future low energy electroweak measurements. We relate the renormalization group evolution of sin 2θ W (µ) to the corresponding evolution ofα(µ) and include higher-order terms in α s and α that had not been treated in previous analyses. We also up-date the analysis of non-perturbative, hadronic contributions and argue that the associated uncertainty is small compared to anticipated experimental errors. The resulting value of the low-energy MS weak mixing angle is sin 2θ W (0) = 0.23867 ± 0.00016.
We discuss the results of a global fit to precision data in supersymmetric models. We consider bo... more We discuss the results of a global fit to precision data in supersymmetric models. We consider both gravity- and gauge-mediated models. As the superpartner spectrum becomes light, the global fit to the data typically results in larger values of chi^2. We indicate the regions of parameter space which are excluded by the data. We discuss the additional effect of the B(B --> X_s\gamma) measurement. Our analysis excludes chargino masses below MZ in the simplest gauge-mediated model with mu>0, with stronger constraints for larger values of tan beta.
We discuss the prospects for measuring the W mass and width in Run II. The basic techniques used ... more We discuss the prospects for measuring the W mass and width in Run II. The basic techniques used to measure M{sub W} are described and the statistical, theoretical and detector-related uncertainties are discussed in detail. Alternative methods of measuring the W mass at the Tevatron and the prospects for M{sub W} measurements at other colliders are also described.
Revista Mexicana De Fisica, Dec 21, 2002
I present an update on the electroweak radiative correction factor to semileptonic tau decays, in... more I present an update on the electroweak radiative correction factor to semileptonic tau decays, including a next-to-leading order resummation of large logarithms. My result differs both qualitatively and quantitatively from the one recently obtained by Davier et al. As two consequences, (i) the discrepancy between the predictions for the muon g-2 based on tau decay data and electron-positron annihilation data increases, and (ii) the g-2 prediction based on tau decay data appears to be consistent (within about one standard deviation) with the experimental result from BNL.
I review and compare various techniques to obtain the value of the QED coupling, alpha, at the Z ... more I review and compare various techniques to obtain the value of the QED coupling, alpha, at the Z pole. GigaZ precisions would require a much more accurate determination than available today. A combination of the virtues of current methods may help to achieve this goal.
Section 10 of the 2004 edition of the Review of Particle Physics.
We present a new QCD sum rule with high sensitivity to the continuum regions of charm and bottom ... more We present a new QCD sum rule with high sensitivity to the continuum regions of charm and bottom quark pair production. Combining this sum rule with existing ones yields very stable results for the msbar quark masses, m_c(m_c)$ and m_b (m_b). Comparison of our approach with experimental data allows for a robust theoretical error estimate. We have also provided a new evaluation of the lifetime of the tau lepton, serving as a strong constraint on alpha_s.
AIP Conference Proceedings, 2006
A brief review of electroweak precision data from LEP, SLC, the Tevatron, and low energies is pre... more A brief review of electroweak precision data from LEP, SLC, the Tevatron, and low energies is presented. The global fit to all data including the most recent results on the masses of the top quark and the W boson reinforces the preference for a relatively light Higgs boson. I will also give an outlook on future developments at the Tevatron Run II, CEBAF, the LHC, and the ILC.
Journal of Physics: Conference Series, 2005
The theoretical and experimental bases of neutrino mass and mixing are reviewed. A brief chronolo... more The theoretical and experimental bases of neutrino mass and mixing are reviewed. A brief chronological evolution of the weak interactions, the electroweak Standard Model, and neutrinos is presented. Dirac and Majorana mass terms are explained as well as models such as the seesaw mechanism. Schemes for two, three and four neutrino mixings are presented.
Phys Rev D, 1999
I calculate the QED coupling, alpha, directly in the MS-bar scheme using an unsubtracted dispersi... more I calculate the QED coupling, alpha, directly in the MS-bar scheme using an unsubtracted dispersion relation for the three light quarks, and perturbative QCD for charm and bottom quarks. Compact analytical expressions are presented, making this approach particularly suitable for electroweak fits. After alpha^(-1) (m_tau) = 133.513 +- 0.025 is obtained in a first step, I perform a 4-loop renormalization group evolution with 3-loop matching conditions to arrive at alpha^(-1) (M_Z) = 127.934 +- 0.026 for alpha_s (M_Z) = 0.120. The corresponding hadronic contribution to the on-shell coupling is Delta alpha_had^(5) (M_Z) = 0.02779 +- 0.00019. The error is mainly from m_c, and from experimental uncertainties in e^+ e^- annihilation into unflavored and strange hadrons and tau decay data.
Physical Review Letters, 2010
There has been renewed interest in the possibility of additional fermion generations. At the same... more There has been renewed interest in the possibility of additional fermion generations. At the same time there have been significant changes in the relevant electroweak precision constraints, in particular, in the interpretation of several of the low energy experiments. We summarize the various motivations for extra families and analyze them in view of the latest electroweak precision data.
AIP Conference Proceedings, 2006
The status in electroweak precision physics is reviewed. I present a brief summary of the latest ... more The status in electroweak precision physics is reviewed. I present a brief summary of the latest data, global fit results, a few implications for new physics, and an outlook.
Journal of Physics: Conference Series, 2005
We perform a global analysis of electroweak precision measurements to find constraints on physics... more We perform a global analysis of electroweak precision measurements to find constraints on physics beyond the Standard Model. In particular, we discuss oblique parameters, which are useful to constrain additional matter fields, as well as extra ZZZ bosons, and supersymmetry. We also summarize the present information on the Higgs boson mass.
Phys Rev Lett, 1996
In supersymmetric models with R-parity violation, scalar neutrinos may be produced as s-channel r... more In supersymmetric models with R-parity violation, scalar neutrinos may be produced as s-channel resonances in e^+e^- colliders. We note that within current constraints, the scalar neutrino may have a width of several GeV into b\bar{b} and be produced with large cross section, leading to a novel supersymmetry discovery signal at LEP II. In addition, if the scalar neutrino mass approximately equals m_Z, such a resonance necessarily increases R_b and reduces A_{FB}(b), significantly improving the fit to electroweak data. Bounds from B meson and top quark decays are leading constraints, and we stress the importance of future measurements.
Journal of Physics G Nuclear and Particle Physics, 2003
I review how electroweak precision observables can be used to constrain the Higgs boson mass and ... more I review how electroweak precision observables can be used to constrain the Higgs boson mass and the strong coupling constant. Implications for physics beyond the standard model are also addressed.