Study of scintillation light collection, production and propagation in a 4 tonne dual-phase LArTPC

The $3 \times 1 \times 1$ m$^3$ demonstrator is a dual phase liquid argon time projection chamber that has recorded cosmic rays events in 2017 at CERN. The light signal in these detectors is crucial to provide precise timing capabilities. The performances of the photon detection system, composed of five PMTs, are discussed. The collected scintillation and electroluminescence light created by passing particles has been studied in various detector conditions. In particular, the scintillation light production and propagation processes have been analyzed and compared to simulations, improving the understanding of some liquid argon properties.

EFFECTS OF BSMS ON θ23 DETERMINATION

The next-generation liquid-scintillator neutrino observatory LENA

We propose the liquid-scintillator detector LENA (Low Energy Neutrino Astronomy) as a next-generation neutrino observatory on the scale of 50 kt. The outstanding successes of the Borexino and KamLAND experiments demonstrate the large potential of liquid-scintillator detectors in low-energy neutrino physics. LENA's physics objectives comprise the observation of astrophysical and terrestrial neutrino sources as well as the investigation of neutrino oscillations. In the GeV energy range, the search for proton decay and long-baseline neutrino oscillation experiments complement the low-energy program. Based on the considerable expertise present in European and international research groups, the …

Advantages of locating LAGUNA in Pyhäsalmi mine

Abstract LAGUNA is the next-generation underground Megaton-scale detector for the search for proton decay, for neutrino astrophysics and for the investigation of neutrino properties. A brief description of the three considered detector technologies is given and the main physics goals presented. While many of the research topics for LAGUNA are not affected by the geographical location of the detector, there are two areas where it is very important: low-energy neutrino measurements and long-baseline neutrino oscillations. Evaluation of the physics arguments in both cases indicates Pyhasalmi mine as the best European site for LAGUNA.

Determination of the θ23 octant in long baseline neutrino experiments within and beyond the standard model

The recent data indicate that the neutrino mixing angle $\theta_{23}$ deviates from the maximal-mixing value of 45$^\circ$, showing two nearly degenerate solutions, one in the lower octant (LO) ($\theta_{23}45^\circ$). We investigate, using numerical simulations, the prospects for determining the octant of $\theta_{23}$ in the future long baseline oscillation experiments. We present our results as contour plots on the ($\theta_{23}-45^\circ$, $\delta$)--plane, where $\delta$ is the $CP$ phase, showing the true values of $\theta_{23}$ for which the octant can be experimentally determined at 3$\,\sigma$, 2$\,\sigma$ and 1$\,\sigma$ confidence level. In particular, we study the impact of the p…

Neutrino conversions in hot plasma

We discuss the excitation of sterile neutrinos in the early universe using general quantum kinetic equations, which also incorporate a possible primordial magnetic field $B$. We find a new contribution to the excitation propability, which has its origin in the shrinkage of the spin vector. In the absence of $B$ nucleosynthesis implies the constraint $\mid \Delta m^2\mid\sin^22\theta_0\lsim 1.6\times 10^{-6}~{\rm eV}^2$ which is more restrictive than previous estimates. We also present examples of possible stringent limits for $B\ne 0$.

Anomalous Higgs–top-quark couplings in the MSSM

The anomalous couplings of the top quark and the Higgs boson have been studied in an effective theory deduced from the minimal supersymmetric extension of the standard model as the heavy fields are integrated out. Constraints on the parameters of the model from the experimental data of ${R}_{b}=\ensuremath{\Gamma}(\stackrel{\ensuremath{\rightarrow}}{Z}b\overline{b})/\ensuremath{\Gamma}(\stackrel{\ensuremath{\rightarrow}}{Z}\mathrm{hadrons})$ are obtained.

Two-loop gluino contributions to the neutron electric dipole moment in theCP-violating minimal supersymmetric standard model

We analyze two-loop gluino corrections to the neutron electric dipole moment (EDM) in the minimal supersymmetry extension of the standard model (MSSM). The dependence of two-loop corrections on the relevant CP violating phases differs from that of the one-loop contributions, and there is a region in the parameter space where the two-loop contributions are comparable with the one-loop contributions. Our numerical results show that the two-loop corrections can be as large as 30% of the one-loop results.

Determination of the $\theta_{23}$ octant in LBNO

According to the recent results of the neutrino oscillation experiment MINOS, the neutrino mixing angle $\theta_{23}$ may not be maximal ($45^{\circ}$). Two nearly degenerate solutions are possible, one in the lower octant (LO) where $\theta_{23}45^{\circ}$. Long baseline experiments measuring the $\nu_{\mu}\rightarrow\nu_{e}$ are capable of resolving this degeneracy. In this work we study the potential of the planned European LBNO experiment to distinguish between the LO and HO solutions.

The two-loop supersymmetric corrections to lepton anomalous magnetic and electric dipole moments

Using the effective Lagrangian method, we analyze the electroweak corrections to the anomalous dipole moments of lepton from some special two-loop topological diagrams which are composed of neutralino (chargino) - slepton (sneutrino) in the minimal supersymmetric extension of the standard model (MSSM). Considering the translational invariance of the inner loop momenta and the electromagnetic gauge invariance, we get all dimension 6 operators and derive their coefficients. After applying equations of motion to the external leptons, the anomalous dipole moments of lepton are obtained. The numerical results imply that there is a parameter space where the two-loop supersymmetric corrections to …

Opiskelija on OPS-uudistuksen kiintopiste

The mass-hierarchy and CP-violation discovery reach of the LBNO long-baseline neutrino experiment.

The next generation neutrino observatory proposed by the LBNO collaboration will address fundamental questions in particle and astroparticle physics. The experiment consists of a far detector, in its first stage a 20 kt LAr double phase TPC and a magnetised iron calorimeter, situated at 2300 km from CERN and a near detector based on a high-pressure argon gas TPC. The long baseline provides a unique opportunity to study neutrino flavour oscillations over their 1st and 2nd oscillation maxima exploring the $L/E$ behaviour, and distinguishing effects arising from $\delta_{CP}$ and matter. In this paper we have reevaluated the physics potential of this setup for determining the mass hierarchy (M…

New constraints on R-parity violation from μ–e conversion in nuclei

We derive new constraints on the products of explicitly R-parity violating couplings $\lambda$ and $\lambda'$ in MSSM from searches for \mu-e conversion in nuclei. We concentrate on the loop induced photonic coherent conversion mode. For the combinations $|\lambda\lambda|$ which in \mu-e conversion can be probed only at loop level our constraints are in many cases more stringent than the previous ones due to the enhancement of the process by large $\ln(m^2_f/m^2_{\tilde f}).$ For the combinations of $|\lambda'\lambda'|$ the tree-level \mu-e conversion constraints are usually more restrictive than the loop ones except for two cases which involve the third generation. With the expected improv…

Runar Viktor Gåsström : fyysikko kylmän sodan aikakaudelta

Constraints on doubly charged Higgs interactions at linear collider

Production of a single doubly charged Higgs boson $Delta^{--}$ in polarized $e^+e^-$ and $e^+\gamma$ collision modes of the linear collider have been investigated. The mass range of $Delta^{--}$ to be probed extends up to the collision energy. The diagonal lepton number violating Yukawa coupling $h_{ee}$ will be tested at least three orders of magnitude more strictly than in present experiments.

Doubly charged Higgs at LHC

We have investigated production of doubly charged Higgs particles $\Delta_{L,R}^{++}$ via WW fusion process in proton-proton collisions at LHC energies in the framework of the left-right symmetric model. The production cross section of the right-triplet Higgs is for representative values of model parameters at femtobarn level. The discovery reach depends on the mass of the right-handed gauge boson W_R. At best $\Delta_R^{++}$ mass up to 2.4 TeV are achievable within one year run. For $\Delta^{++}_L$ the corresponding limit is 1.75 TeV which depends on the value of the left-triplet vev v_L. Comparison with Drell-Yan pair production processes shows that studies of the WW fusion processes exte…

A 4 tonne demonstrator for large-scale dual-phase liquid argon time projection chambers

A 10 kilo-tonne dual-phase liquid argon TPC is one of the detector options considered for the Deep Underground Neutrino Experiment (DUNE). The detector technology relies on amplification of the ionisation charge in ultra-pure argon vapour and offers several advantages compared to the traditional single-phase liquid argon TPCs. A 4.2 tonne dual-phase liquid argon TPC prototype, the largest of its kind, with an active volume of \three has been constructed and operated at CERN. In this paper we describe in detail the experimental setup and detector components as well as report on the operation experience. We also present the first results on the achieved charge amplification, prompt scintillat…

Revisiting pseudo-Dirac neutrinos

We study the pseudo-Dirac mixing of left and right-handed neutrinos in the case where the Majorana masses M_L and M_R are small when compared with the Dirac mass, M_D. The light Majorana masses could be generated by a non-renormalizable operator reflecting effects of new physics at some high energy scale. In this context, we obtain a simple model independent closed bound for M_D. A phenomenologically consistent scenario is achieved with M_L,M_R ~ 10^{-7} eV and M_D ~ 10^{-5}-10^{-4} eV. This precludes the possibility of positive mass searches in the planned future experiments like GENIUS or in tritium decay experiments. If on the other hand, GENIUS does observe a positive signal for a Major…

Effects of triplet Higgs bosons in long baseline neutrino experiments

The triplet scalars $(\Delta=\Delta^{++},\Delta^{+},\Delta^{0})$, utilized in the so-called Type-II seesaw model to explain the lightness of neutrinos, would generate nonstandard interactions (NSI) for neutrino propagating in matter. We investigate the prospects to probe these interactions in long baseline neutrino oscillation experiments. We analyze the upper bounds that the proposed DUNE experiment might set on the nonstandard parameters and numerically derive upper bounds, as function of the lightest neutrino mass, on the ratio the mass $M_\Delta$ of the triplet scalars and strength $|\lambda_\phi|$ of the coupling $\phi\phi\Delta$ of the triplet $\Delta$ and conventional Higgs doublet $…

Neutrinos confronting large extra dimensions

We study neutrino physics in a model with one large extra dimension. We assume the existence of two four-dimensional branes in the five-dimensional space-time, one for the ordinary particles and the other one for mirror particles, and we investigate neutrino masses and mixings in this scheme. Comparison of experimental neutrino data with the predictions of the model leads to various restrictions on the parameters of the model. For instance, the size of the extra dimension, R, turns out to be bounded from below. Cosmological considerations seem to favor a large R. The usual mixing schemes proposed as solutions to the solar and atmospheric neutrino anomalies are compatible with our model.

Single production of doubly charged Higgs bosons at hadron colliders

We reconsider the single production of the doubly charged Higgs bosons Delta_R^{++} and Delta_L^{++} at the LHC and TEVATRON in the framework of the left-right symmetric model and the Higgs triplet model. We show that in the left-right symmetric model the production of Delta_R^{++} by Drell-Yan process via W_R exchange may give the dominant contribution. The same channel for the production of Delta_L^{++} in the Higgs triplet model is insignificant.

Constraining the nonstandard interaction parameters in long baseline neutrino experiments

In this article we investigate the prospects for probing the strength of the possible non-standard neutrino interactions (NSI) in long baseline neutrino oscillation experiments. We find that these experiments are sensitive to NSI couplings down to the level of 0.01-0.1 depending on the oscillation channel and the baseline length, as well as on the detector's fiducial mass. We also investigate the interference of the leptonic CP angle $\delta_{CP}$ with the constraining of the NSI couplings. It is found that the interference is strong in the case of the $\nu_{e}\leftrightarrow\nu_{\mu}$ and $\nu_{e}\leftrightarrow\nu_{\tau}$ transitions but not significant in other transitions. In our numeri…

Neutrinoless double beta-plus/EC decays

The relation of neutrino masses to neutrino oscillations and the nuclear double beta decay is highlighted. In particular, the neutrinoless 𝛽+ 𝛽+, 𝛽+EC, and resonant ECEC decays are investigated using microscopic nuclear models. Transitions to the ground state and excited 0+ states are analyzed. Systematics of the related nuclear matrix elements are studied and the present status of the resonant ECEC decays is reviewed. peerReviewed

Effects of degenerate sterile neutrinos on the supernova neutrino flux

We consider the possibility that there exist sterile neutrinos which are closely degenerate in mass with the active neutrinos and mixed with them. We investigate the effects of this kind of active-sterile neutrino mixing on the composition of supernova neutrino flux at the Earth. If an adiabatic MSW-transition between active and sterile neutrinos takes place, it could dramatically diminish the electron neutrino flux.

Oscillations of Dirac and Majorana neutrinos in matter and a magnetic field

We study the evolution of massive mixed Dirac and Majorana neutrinos in matter under the influence of a transversal magnetic field. The analysis is based on relativistic quantum mechanics. We solve exactly the evolution equation for relativistic neutrinos, find the neutrino wave functions, and calculate the transition probability for spin-flavor oscillations. We analyze the dependence of the transition probability on the external fields and compare the cases of Dirac and Majorana neutrinos. The evolution of Majorana particles in vacuum is also studied and correction terms to the standard oscillation formula are derived and discussed. As a possible application of our results we discuss the s…

Heavy neutrino mixing and single production at linear collider

We study the single production of heavy neutrinos via the processes $e^-e^+ \to \nu N$ and $e^-\gamma \to W^- N$ at future linear colliders. As a base of our considerations we take a wide class of models, both with vanishing and non-vanishing left-handed Majorana neutrino mass matrix $m_L$. We perform a model independent analyses of the existing experimental data and find connections between the characteristic of heavy neutrinos (masses, mixings, CP eigenvalues) and the $m_L$ parameters. We show that with the present experimental constraints heavy neutrino masses almost up to the collision energy can be tested in the future experiments.

Sterile neutrino signals from supernovae

We investigate the effects of a mixing of active and sterile neutrinos on the ratios of supernova electron neutrino flux ($F_e$) and antineutrino flux ($F_{\bar e}$) to the total flux of the other neutrino and antineutrino flavours ($F_a$). We assume that the heaviest (in the normal hierarchy) Standard Model neutrino $\nu_3$ mixes with a sterile neutrino resulting in a pair of mass eigenstates with a small mass gap. Using the density matrix formalism we solve numerically the the evolution of neutrino states in the envelope of a supernova and determine the flux ratios $F_e/F_a$ and $F_{\bar{e}}/F_a$ as a function of the active-sterile mixing angle and for the experimentally allowed range of …

Landau-Zener problem in a three-level neutrino system with non-linear time dependence

We consider the level-crossing problem in a three-level system with non-linearly time-varying Hamiltonian (time-dependence $t^{-3}$). We study the validity of the so-called independent crossing approximation in the Landau-Zener model by making comparison with results obtained numerically in density matrix approach. We also demonstrate the failure of the so-called "nearest zero" approximation of the Landau-Zener level-crossing probability integral.

Ultra–High‐Energy Cosmic Rays from Hypothetical Quark Novae

We explore acceleration of ions in the Quark Nova (QN) scenario, where a neutron star experiences an explosive phase transition into a quark star (born in the propeller regime). In this picture, two cosmic ray components are isolated: one related to the randomized pulsar wind and the other to the propelled wind, both boosted by the ultra-relativistic Quark Nova shock. The latter component acquires energies $10^{15} {\rm eV} 10^{18.6}$ eV. The composition is dominated by ions present in the pulsar wind in the energy range above $10^{18.6}$ eV, while at energies below $10^{18}$ eV the propelled ejecta, consisting of the fall-back neutron star crust material from the explosion, is the dominant…

Evolution of Mixed Dirac Particles Interacting with an External Magnetic Field

We study in the framework of relativistic quantum mechanics the evolution of a system of two Dirac neutrinos that mix with each other and have non-vanishing magnetic moments. The dynamics of this system in an external magnetic field is determined by solving the Pauli-Dirac equation with a given initial condition. We consider first neutrino spin-flavor oscillations in a constant magnetic field and derive an analytical expression for the transition probability of spin-flavor conversion in the limit of small magnetic interactions. We then investigate ultrarelativistic neutrinos in an transversal magnetic field and derive their wave functions and transition probabilities with no limitation for …

Determination of the θ23 octant in long baseline neutrino experiments within and beyond the standard model

The recent data indicate that the neutrino mixing angle θ 23 deviates from the maximal-mixing value of 45°, showing two nearly degenerate solutions, one in the lower octant (LO) ( θ 23 4 5 ° ). We investigate, using numerical simulations, the prospects for determining the octant of θ 23 in the future long baseline oscillation experiments. We present our results as contour plots on the ( θ 23 − 4 5 ° , δ )–plane, where δ is the C P phase, showing the true values of θ 23 for which the octant can be experimentally determined at 3 σ , 2 σ and 1 σ confidence level. In particular, we study the impact of the possible nonunitarity of neutrino mixing on the experimental determination of θ 23 in thos…

Thermal leptogenesis in a 5D split fermion scenario with bulk neutrinos

We study the thermal leptogenesis in a hybrid model, which combines the so called split fermion model and the bulk neutrino model defined in five dimensional spacetime. This model predicts the existence of a heavy neutrino pair nearly degenerate in mass, whose decays might generate a CP violation large enough for creating the baryon asymmetry of the universe through leptogenesis. We investigate numerically the constraints this sets on the parameters of the model such as the size of the compactified fifth dimension.

Effects of sterile neutrinos on the ultrahigh-energy cosmic neutrino flux

We investigate the effect of sterile neutrinos that are nearly degenerate with active ones on the flux of ultrahigh-energy cosmic ray neutrinos at earth. This offers a way to probe neutrino oscillations in the mass-squared range (10^{-16} eV^2 < ��m^2 < 10^{-11} eV^2) which maybe hard to detect by any other means. Taking into account the present experimental uncertainties of the active-active mixing angles and by allowing any values for the active-sterile mixing angles we find that the ratio of the electron and muon neutrino fluxes may change by -40 % to 70 % in comparison with the ratio in the absence of active-sterile mixing.

Numerical study of leptogenesis in a 5D split fermion model with bulk neutrinos

We study numerically a 5D hybrid model which incorporates a split fermion scenario and bulk neutrinos. We perform a Monte Carlo analysis of the model in order to find the regions in the parameter space allowing for realization of the leptogenesis. We find that higher order Yukawa terms must be included in order the model to produce a CP violation and net baryon number sufficient for the creation of the observed baryon asymmetry of the Universe.

Optimizing the θ23 octant search in long baseline neutrino experiments

Determination of the θ 23 octant will be an important goal for the next generation of neutrino oscillation experiments, as it will show whether the true value of θ 23 lies in the high octant, θ 23 > 45°, or in the low octant, θ 23 < 45°. In this work we investigate the prospects of studying the θ 23 octant in future long baseline neutrino experiments. Using the GLoBES software, we study the sensitivity to θ 23 octant in terms of baseline length and beam sharing and use the LBNO setup as our benchmark. We also show the interference on the octant determination that arises from the unconstrained CP violation angle δ CP. In our results, we show the impact of matter effects on the octant determi…

Large underground, liquid based detectors for astro-particle physics in Europe: scientific case and prospects

This document reports on a series of experimental and theoretical studies conducted to assess the astro-particle physics potential of three future large-scale particle detectors proposed in Europe as next generation underground observatories. The proposed apparatus employ three different and, to some extent, complementary detection techniques: GLACIER (liquid Argon TPC), LENA (liquid scintillator) and MEMPHYS (\WC), based on the use of large mass of liquids as active detection media. The results of these studies are presented along with a critical discussion of the performance attainable by the three proposed approaches coupled to existing or planned underground laboratories, in relation to…

A scheme with two large extra dimensions confronted with neutrino physics

We investigate a particle physics model in a six-dimensional spacetime, where two extra dimensions form a torus. Particles with Standard Model charges are confined by interactions with a scalar field to four four-dimensional branes, two vortices accommodating ordinary type fermions and two antivortices accommodating mirror fermions. We investigate the phenomenological implications of this multibrane structure by confronting the model with neutrino physics data.