arXiv subjects

M. Lindner

Publications and source records attributed to M. Lindner.

At least 217 records · Page 12Linked to original sources

arXiv2004

Simulation of long-baseline neutrino oscillation experiments with GLoBES

We present the GLoBES (``General Long Baseline Experiment Simulator'') software package, which allows the simulation of long-baseline and reactor neutrino oscillation experiments. One part of the software is the abstract experiment definition language to define experiments with beam and full detector descriptions as accurate as possible. Many systematics options are provided, such as normalization and energy calibration errors, or the choice between spectral or total rate information. For the definition of experiments, a new transparent building block concept is introduced. In addition, an additional program provides the possibility to develop and test new experiment definitions quickly. Another part of GLoBES is the user's interface, which provides probability, rate, and $Δχ^2$ information for a given experiment or any combination of up to 32 experiments in C. Especially, the $Δχ^2$ functions allow a simulation with statistics only, systematics, correlations, and degeneracies. In particular, GLoBES can handle the full multi-parameter correlation among the oscillation parameters, external input, and matter density uncertainties.

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arXiv2004

Letter of Intent for Double-CHOOZ: a Search for the Mixing Angle Theta13

Tremendous progress has been achieved in neutrino oscillation physics during the last few years. However, the smallness of the $\t13$ neutrino mixing angle still remains enigmatic. The current best constraint comes from the CHOOZ reactor neutrino experiment $\s2t13 < 0.2$ (at 90% C.L., for $\adm2=2.0 10^{-3} \text{eV}^2$). We propose a new experiment on the same site, Double-CHOOZ, to explore the range of $\s2t13$ from 0.2 to 0.03, within three years of data taking. The improvement of the CHOOZ result requires an increase in the statistics, a reduction of the systematic error below one percent, and a careful control of the cosmic ray induced background. Therefore, Double-CHOOZ will use two identical detectors, one at $\sim$150 m and another at 1.05 km distance from the nuclear cores. The plan is to start data taking with two detectors in 2008, and to reach a sensitivity of 0.05 in 2009, and 0.03 in 2011.

hep-ex↗

arXiv2004

Series expansions for three-flavor neutrino oscillation probabilities in matter

We present a number of complete sets of series expansion formulas for neutrino oscillation probabilities in matter of constant density for three flavors. In particular, we study expansions in the mass hierarchy parameter $α\equiv Δm_{21}^2/Δm_{31}^2$ and mixing parameter $s_{13} \equiv \sin θ_{13}$ up to second order and expansions only in $α$ and only in $s_{13}$ up to first order. For each type of expansion we also present the corresponding formulas for neutrino oscillations in vacuum.We perform a detailed analysis of the accuracy of the different sets of series expansion formulas and investigate which type of expansion is most accurate in different regions of the parameter space spanned by the neutrino energy E, the baseline length L, and the expansion parameters $α$ and $s_{13}$.We also present the formulas for series expansions in $α$ and in $s_{13}$ up to first order for the case of arbitrary matter density profiles. Furthermore, it is shown that in general all the 18 neutrino and antineutrino oscillation probabilities can be expressed through just two independent probabilites.

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arXiv2002

The Physics Potential of Future Long Baseline Neutrino Oscillation Experiments

We discuss in detail different future long baseline neutrino oscillation setups and we show the remarkable potential for very precise measurements of mass splittings and mixing angles. Furthermore it will be possible to make precise tests of coherent forward scattering and MSW effects, which allow to determine the sign of $Δm^2$. Finally strong limits or measurements of leptonic CP violation will be possible, which is very interesting since it is most likely connected to the baryon asymmetry of the universe.

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arXiv2002

Synergies between the first-generation JHF-SK and NuMI superbeam experiments

We discuss synergies in the combination of the first-generation JHF to Super-Kamiokande and NuMI off-axis superbeam experiments. With synergies we mean effects which go beyond simply adding the statistics of the two experiments. As a first important result, we do not observe interesting synergy effects in the combination of the two experiments as they are planned right now. However, we find that with minor modifications, such as a different NuMI baseline or a partial antineutrino running, one could do much richer physics with both experiments combined. Specifically, we demonstrate that one could, depending on the value of the solar mass squared difference, either measure the sign of the atmospheric mass squared difference or CP violation already with the initial stage experiments. Our main results are presented in a way that can be easily interpreted in terms of the forthcoming KamLAND result.

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arXiv2002

Single Photon X-Ray Imaging with Si- and CdTe-Sensors

Studies of a single photon counting hybrid pixel detector for X-ray imaging applications are presented. A silicon- and a CdTe-sensor were bump bonded onto the MPEC pixel readout chip and could be successfully operated. A new USB based readout system was used for data acquisition. Measurements of the performance on the latest MPEC chip and imaging characterization of the sensors are presented.

hep-ex↗

arXiv2001

T violation in neutrino oscillations in matter

We consider the interplay of fundamental and matter-induced T violation effects in neutrino oscillations in matter. After discussing the general features of these effects we derive a simple approximate analytic expression for the T-violating probability asymmetry ΔP^T_{ab} for three-flavour neutrino oscillations in a matter with an arbitrary density profile in terms of the two-flavour neutrino amplitudes. Explicit examples are given for the cases of a two-layer medium and for the adiabatic limit in the general case. We then discuss implications of the obtained results for long baseline experiments. We show, in particular, that asymmetric matter effects cannot hinder the determination of the fundamental CP and T-violating phase δ_{CP} in the long baseline experiments as far as the error in this determination is larger than 1% at 99% C.L. Since there are no T-violating effects in the two-flavour case, and in the limits of vanishing θ_{13} or Δm_{21}^2 the three-flavour neutrino oscillations effectively reduce to the two-flavour ones, studying the T-violating asymmetries ΔP^T_{ab} can in principle provide us with a complementary means of measuring θ_{13} and Δm_{21}^2.

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arXiv2001

Systematic Exploration of the Neutrino Factory Parameter Space including Errors and Correlations

We discuss in a systematic way the extraction of neutrino masses, mixing angles and leptonic CP violation at neutrino factories. Compared to previous studies we put a special emphasis on improved statistical methods and on the multidimensional nature of the combined fits of the nu_e -> nu_mu, \bar nu_e -> \bar nu_mu appearance and nu_mu -> nu_mu, \bar nu_mu -> \bar nu_mu disappearance channels. Uncertainties of all involved parameters and statistical errors are included. We find previously ignored correlations in the multidimensional parameter space, leading to modifications in the physics reach, which amount in some cases to one order of magnitude. Including proper statistical errors we determine for all parameters the improved sensitivity limits for various baselines, beam energies, neutrino fluxes and detector masses. Our results allow a comparison of the physics potential for different choices of baseline and beam energy with regard to all involved parameters. In addition we discuss in more detail the problem of parameter degeneracies in measurements of delta_CP.

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arXiv2000

A Comparison of the Physics Potential of Future Long Baseline Neutrino Oscillation Experiments

We compare the generic physics potential of various combinations of conventional Wide Band or Neutrino Factory Beams with different detectors to determine several oscillation parameters in long baseline experiments. For each combination of beam and detector we show the precision which can be obtained for the leading oscillation parameters $\dm{31}$ and $\sin^2 2θ_{23}$. Furthermore we show the sensitivity to $\sin^2 2θ_{13}$ and the range in $\sin^2 2θ_{13}$ for which the sign of $\dm{31}$ can be extracted via matter effects. The results suggest that existing conventional Wide Band Beam and detector technology can be used to considerably improve the precision of neutrino properties until a neutrino factory will be built.

hep-ph↗

arXiv2000

Masses and Mixings from Neutrino Beams pointing to Neutrino Telescopes

We discuss the potential to determine leading oscillation parameters, the value and the sign of Δm^2_{31}, as well as the magnitude of \sin^2 2θ_{13} using a conventional wide band neutrino beam pointing to water or ice Cherenkov neutrino detectors known as ``Neutrino Telescopes''. We find that precision measurements of Δm^2_{31} and θ_{23} are possible and that, even though it is not possible to discriminate between charges in the detector, there is a remarkably good sensitivity to the mixing angle θ_{13} and the sign of Δm^2_{31}.

hep-ph↗

arXiv2000

Extracting Matter Effects, Masses and Mixings at a Neutrino Factory

We discuss and quantify different possibilities to determine matter effects, the value and the sign of $Delta m^2_{31}$, as well as the magnitude of $\sin^2 2θ_{13}$ in very long baseline neutrino oscillation experiments. We study neutrino oscillation at a neutrino factory in the $ν_μ\toν_μ$ disappearance and $ν_e\toν_μ$ appearance channels with and without muon charge identification. One possibility is to analyze the $ν_e\toν_μ$ appearance channels leading to wrong sign muon events, which requires however very good muon charge identification. Without charge identification it is still possible to operate the neutrino factory both with $μ^-$ and $μ^+$ beams and to analyze the differences in the total neutrino event rate spectra. We show that this leads already to a quite good sensitivity, which may be important if right sign charge rejection capabilities are insufficient. With muon charge identification one can study the $ν_μ\toν_μ$ disappearance and the $ν_e\toν_μ$ appearance channels independently. The best method is finally achieved by combining all available information of the $ν_μ\toν_μ$ disappearance and $ν_e\toν_μ$ appearance channels with charge identification and we show the sensitivity which can be achieved.

hep-ph↗

arXiv2000

Testing Matter Effects in Very Long Baseline Neutrino Oscillation Experiments

Assuming three-neutrino mixing, we study the capabilities of very long baseline neutrino oscillation experiments to verify and test the MSW effect and to measure the lepton mixing angle theta_13. We suppose that intense neutrino and antineutrino beams will become available in so-called neutrino factories. We find that the most promising and statistically significant results can be obtained by studying nu_e ->nu_mu and \bar{nu}_e-> \bar{nu}_mu oscillations which lead to matter enhancements and suppressions of wrong sign muon rates. We show the theta_13 ranges where matter effects could be observed as a function of the baseline. We discuss the scaling laws of rates, significances and sensitivities with the relevant mixing angles and experimental parameters. Our analysis includes fluxes, event rates and statistical aspects so that the conclusions should be useful for the planning of experimental setups. We discuss the subleading Delta m^2_{21} effects in the case of the LMA MSW solution of the solar problem, showing that they are small for L >= 7000 km. For shorter baselines, Delta m^2_{21} effects can be relevant and their dependence on L offers a further handle for the determination of the CP-violation phase δ. Finally we comment on the possibility to measure the specific distortion of the energy spectrum due to the MSW effect.

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arXiv1999

CP-violation in neutrino oscillations

We study in a quantitative way CP-violating effects in neutrino oscillation experiments in the light of current and future data. Different scenarios with three and four neutrinos are worked out in detail including matter effects in long baseline experiments and it is shown that in some cases CP-violating effects could affect the analysis of a possible measurement. In particular in the three neutrino case we find that the effects can be larger than expected, at least in long-baseline $ν_μ\toν_e$. Moreover, measuring these effects could give useful information on the solar oscillation frequency. In four neutrino scenarios large effects are possible both in the $ν_μ\toν_τ$ and $ν_μ\toν_e$ channels of long-baseline experiments, whereas short-baseline experiments are affected only marginally.

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arXiv1997

Phenomenologically Viable Dynamical Electro-Weak Symmetry Breaking

The lack of deviations from the Standard Model at the current level of experimental precision can be explained systematically in suitable models of dynamical electro-weak symmetry breaking. The key ingredient is dynamics which produces a scalar unitarity partner for the Goldstone-Bosons and which leads to a decoupling of effects beyond the Standard Model. A phenomenologically successful left-right symmetric model is presented from this point of view.

hep-ph↗

arXiv1995

Dynamical Left-Right Symmetry Breaking

We study a left--right symmetric model which contains only elementary gauge boson and fermion fields and no scalars. The phenomenologically required symmetry breaking emerges dynamically leading to a composite Higgs sector with a renormalizable effective Lagrangian. We discuss the pattern of symmetry breaking and phenomenological consequences of this scenario. It is shown that a viable top quark mass can be achieved for the ratio of the VEVs of the bi--doublet $\tanβ\equivκ/κ'$ =~ 1.3--4. For a theoretically plausible choice of the parameters the right--handed scale can be as low as $\sim 20 TeV$; in this case one expects several intermediate and low--scale scalars in addition to the \SM Higgs boson. These may lead to observable lepton flavour violation effects including $μ\to eγ$ decay with the rate close to its present experimental upper bound.

hep-ph↗

arXiv1995

Left-Right Symmetry Breaking in NJL Approach

We study left-right symmetric models which contain only fermion and gauge boson fields and no elementary scalars. The Higgs bosons are generated dynamically through a set of gauge- and parity-invariant 4-fermion operators. It is shown that in a model with a composite bi-doublet and two triplet scalars there is no parity breaking at low energies, whereas in the model with two doublets instead of two triplets parity is broken automatically regardless of the choice of the parameters of the model. For phenomenologically allowed values of the right-handed scale a tumbling symmetry breaking mechanism is realized in which parity breaking at a high scale $μ_R$ propagates down and eventually causes the \EW symmetry breaking at the scale $μ_{EW}\sim 100~GeV$. The model exhibits a number of low and intermediate mass Higgs bosons with certain relations between their masses. In particular, the components of the $SU(2)_L$ Higgs doublet $χ_L$ are pseudo--\GBs of an accidental (approximate) $SU(4)$ symmetry of the Higgs potential and therefore are expected to be relatively light.

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arXiv1993

The Phenomenological Viability of Top Condensation

We discuss how the full dynamics of top condensation models can modify the relations between the physical top mass, the amount of custodial $SU(2)$ violation and the weak gauge boson masses. It is emphasized that it is possible to get phenomenologically acceptable relations between $Δρ$, $m_t$ and $M_W$ and that in addition the scale of new physics can be chosen to be ${\cal O}(TeV)$ such that a fine--tuning problem is avoided.

hep-ph↗

arXiv1993

Custodial SU(2) Violation and the Origin of Fermion Masses

Custodial $SU(2)$ breaking due to dynamical fermion masses is studied in a rather general context and it is shown how some well known limiting cases are correctly described. The type of ``gap equation'' which can systematically lead to extra negative contributions to the so--called $ρ$--parameter is emphasized. Furthermore general model independent features are discussed and it is shown how electro--weak precision measurements can be sensitive to the fermion content and/or dynamical features of a given theory.

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