SHIP is a new general purpose fixed target facility, whose Technical Proposal has been recently reviewed by the CERN SPS Committee and by the CERN Research Board. The two boards recommended that the experiment proceeds further to a Comprehensive Design phase in the context of the new CERN Working group "Physics Beyond Colliders", aiming at presenting a CERN strategy for the European Strategy meeting of 2019. In its initial phase, the 400GeV proton beam extracted from the SPS will be dumped on a heavy target with the aim of integrating 2×10^20 pot in 5 years. A dedicated detector, based on a long vacuum tank followed by a spectrometer and particle identification detectors, will allow probing a variety of models with light long-lived exotic particles and masses below O(10) GeV /c2. The main focus will be the physics of the so-called Hidden Portals, i.e. search for Dark Photons, Light scalars and pseudo-scalars, and Heavy Neutrinos. The sensitivity to Heavy Neutrinos will allow for the first time to probe, in the mass range between the kaon and the charm meson mass, a coupling range for which Baryogenesis and active neutrino masses could also be explained. Another dedicated detector will allow the study of neutrino cross-sections and angular distributions. ντ deep inelastic scattering cross sections will be measured with a statistics 1000 times larger than currently available, with the extraction of the F4 and F5 structure functions, never measured so far and allow for new tests of lepton non-universality with sensitivity to BSM physics.
Permanent electric dipole moments (EDMs) of fundamental particles provide powerful probes for physics beyond the Standard Model. We propose to search for the EDM of strange and charm baryons at LHC, extending the ongoing experimental program on the neutron, muon, atoms, molecules and light nuclei. The EDM of strange $\Lambda$ baryons, selected from weak decays of charm baryons produced in $pp$ collisions at LHC, can be determined by studying the spin precession in the magnetic field of the detector tracking system. A test of $CPT$ symmetry can be performed by measuring the magnetic dipole moment of $\Lambda$ and $\overline{\Lambda}$ baryons. For short-lived $Λ^+_c$ and $\Xi_c^+$ baryons, to be produced in a fixed-target experiment using the 7 TeV LHC beam and channeled in a bent crystal, the spin precession is induced by the intense electromagnetic field between crystal atomic planes. The experimental layout based on the LHCb detector and the expected sensitivities in the coming years are discussed, along with perspectives for the future
Direct dark matter searches are promising techniques to identify the nature of dark matter
particles. A variety of experiments have been developed over the past decades, aiming at
detecting Weakly Interactive Massive Particles (WIMPs) via their scattering in a detector
medium. Exploiting directionality would give a proof of the galactic origin of dark matter
making it possible to provide a clear and unambiguous signal to background separation. In
particular, the directionality appears as the only way to overcome the neutrino background
that is expected to finally prevent standard techniques to further lower cross-section limits.
The directional detection of Dark Matter requires very sensitive experiment combined with
highly performing technology. The NEWSdm experiment, based on nuclear emulsions, is
proposed to measure the direction of WIMP-induced nuclear recoils and it is expected to
produce a prototype in 2017. We discuss the discovery potential of a directional experiment
based on the use of a solid target made by newly developed nuclear emulsions and read-out
systems reaching sub-micrometric resolution.
The production of electroweak bosons (W, Z or gamma) in association with jets is a stringent
test of perturbative QCD and is a background process in searches for new physics. Total and
differential cross-section measurements of electroweak bosons produced in association with jets
(and heavy flavour quarks) in proton-proton collisions are presented. The data have been
recorded with the CMS detector at the LHC and are compared to the predictions of event
generators and theoretical calculations.
Precision measurements of neutrino oscillation probabilities require an improved understanding of neutrino-nucleus interactions. MINERvA is a neutrino scattering experiment at Fermilab that utilizes the intense neutrino beam from the NuMI beam-line and a finely segmented scintillator based tracking detector to measure neutrino cross sections on various nuclear targets. MINERvA has published results using its low-energy data sets and is presently taking NOvA-era medium energy data. These results cover both exclusive and inclusive channels for muon and electron neutrino and anti-neutrino interactions. A summary of recent results from MINERvA will be presented.
To measure the last unknown 3ν oscillation parameter (δ), several long baseline neutrino experiments have been designed or proposed. Recently it has been shown that turning on neutral current Non-Standard Interactions (NSI) of neutrinos with matter can induce degeneracies that may even hinder the proposed state-of-the-art DUNE long baseline experiment from measuring the value of δ. After a brief review of models that can give rise to sizeable NSI, we show how the result of the proposed MOMENT experiment with a baseline of 150 km and 200 MeV<Eν<600 MeV can help to solve the degeneracy induced by NSI and determine the true value of δ.
The observation of neutrinoless double beta ($0\nu\beta\beta$) decay would prove lepton number violation and would shed light onto the nature of neutrinos. The GERDA experiment is aiming to perform a background free search for this process in $^{76}$Ge by operating isotopically enriched high purity Germanium detectors bare in liquid argon. Phase II of the experiment combines for the first time the excellent properties of semiconductor Germanium detectors with an active background suppression technique based on the simultaneous detection of liquid argon scintillation light by photomultiplier tubes and silicon photomultipliers coupled to scintillating fibers (LAr veto).
This talk outlines the Phase II upgrade with special emphasis on background rejection techniques and focusses on the first results of Phase II. Exhibiting the world-best background index (if normalized to the narrow energy-signal region of Germanium detectors), a limit on the $0\nu\beta\beta$-decay half-life of $^{76}$Ge of $5.3 \cdot 10^{25}$ yr at 90% C.L. could be set based on an exposure of only 34.4 kg$\cdot$yr. With an ultimate exposure of 100 kg$\cdot$yr this will allow for a $0\nu\beta\beta$-decay half-life sensitivity of the GERDA Phase II experiment of $10^{26}$ yr.
A review of the theory and phenomenology of neutrino electromagnetic properties is presented. A massive neutrino even in the easiest generalization of the Standard Model inevitably has nonzero electromagnetic characteristics, at least nonzero magnetic moment. Although its value, determined by the neutrino mass, is very small, in other BSM theories, as for example the supersymmetric models, much larger values of magnetic moments are predicted.
Derivation of the general structure of the electromagnetic interactions of Dirac and Majorana neutrinos is presented. Then we discuss experimental constraints on neutrino magnetic and electric dipole moments, electric millicharge, charge radius and anapole moments from the terrestrial laboratory experiments. A special credit is done to bounds on neutrino magnetic moments obtained by the reactor (MUNU, TEXONO and GEMMA) and solar (Super-Kamiokande and Borexino) experiments. The effects of neutrino electromagnetic interactions in astrophysical environments are also reviewed. The main manifestation of neutrino electromagnetic interactions, such as: 1) the radiative decay in vacuum, in matter and in a magnetic field, 2) the Cherenkov radiation, 3) the plasmon decay, 4) spin light in matter, 5) spin and spin-flavour precession, 6) neutrino pair production in a strong magnetic field, and the related processes along with their astrophysical phenomenology are also considered.
The best world experimental bounds on neutrino electromagnetic properties are confronted with the predictions of theories beyond the Standard Model. It is shown that studies of neutrino electromagnetic properties provide powerful tools to probe the physics beyond the Standard Model.
References
[1] C. Guinti and A. Studenikin, “Neutrino electromagnetic interactions: a window to new physics”, Rev. Mod. Phys., V.87, 2015, p. 531-591.
[2] A. Studenikin, “New bounds on neutrino electric millicharge from limits on neutrino magnetic moment”, Europhys. Lett. 107 (2014) 21001.
[3] A. Studenikin, I. Tokarev, “Millicharged neutrino with anomalous magnetic moment in rotating magnetized matter”, Nucl. Phys. B 884 (2014) 396-407.
[4] K. Kouzakov, A. Studenikin, “Theory of neutrino-atom collisions: the history, present status and BSM physics”, Adv. High Energy Phys. 2014 (2014) 569409 (16 p.).
[5] I.. Balantsev, A. Studenikin, “From electromagnetic neutrinos to new electromagnetic radiation mechanism in neutrino fluxes”, Int. J. Mod. Phys. A30 (2015) 1530044 (10 p) .
[6] A. Studenikin, Neutrino spin and spin-flavour oscillations in transversally moving or polarized matter, arXiv: 1610.06563.
New constraints on neutrino electromagnetic properties will be reviewed in the talk, including our new results on neutrino magnetic moment and millicharge, recently published:
[2] A. Studenikin, “New bounds on neutrino electric millicharge from limits on neutrino magnetic moment”, Europhys. Lett. 107 (2014) 21001.
[3] A. Studenikin, I. Tokarev, “Millicharged neutrino with anomalous magnetic moment in rotating magnetized matter”, Nucl. Phys. B 884 (2014) 396-407.
I would like to note that a new bound on neutrino millichage obtained in [2] has been included by «Particle Data Group Collaboration» in the list of the list of neutrino properties in «The Review of Particle Physics 2016» (C. Patrignani et al (Particle Data Group), Chinese Physics C 40, No. 10 (2016) 100001).
In my talk I shall also discuss a new effect of the neutrino spin oscillations engendered by interactions with the transversal currents of matter. This effect was proposed by myself several years ago, see details in:
[6] A. Studenikin, Neutrino spin and spin-flavour oscillations in transversally moving or polarized matter, arXiv: 1610.06563.
The existence of this effect and its importance in consideration of neutrino fluxes from supernovae has been shown in a series of papers:
[7] V. Cirigliano, G. Fuller, A. Vlasenko, Phys. Lett. B 747, 27 (2015);
[8] C. Volpe, Int. J. Mod.Phys. E 24, 1541009 (2015);
[9] A. Kartavtsev, G. Raffelt and H. Vogel, Phys. Rev. D 91, 125020 (2015);
[10] A. Dobrynina, A. Kartavtsev and G. Raffelt, Phys. Rev. D 93 (2016) no.12, 125030.
The relaxion proposal is a new alternative to justify the smallness of the Higgs mass. The idea is to explain the radiative stability of the Higgs sector through the cosmological relaxation mechanism of the electroweak scale. Typically, in this framework, the effective Higgs mass is scanned by a scalar field (the relaxion) starting at some large value which slowly decreases during inflation. We propose a UV completion for the relaxion idea in the context of warped extra dimension scenarios. In our construction, the warp factor can naturally explain the large hierarchy between the decay constants in the relaxion potential.
We present a model of spontaneous (or dynamical) C and CP violation where it is possible to generate domains of matter and antimatter separated by cosmologically large distances. Such C(CP) violation existed only in the early universe and later it disappeared with the only trace of generated baryonic and/or antibaryonic domains. So the problem of domain walls in this model does not exist. These features are achieved through a postulated form of interaction between inflaton and a new scalar field, realizing short time C(CP) violation.
For the realization of this scenario the width of the domain wall should grow exponentially. Though there is a classical result found in paper by Basu and Vilenkin that the width of the wall tends to the one of the stationary solution. That is why we considered thick domain walls in a de Sitter universe following paper by Basu and Vilenkin. However, we are interested not only in stationary solutions found therein, but also investigated the general case of domain wall evolution with time. When the wall thickness parameter, $\delta_0$, is smaller than $H^{−1}/\sqrt{2}$, where $H$ is the Hubble parameter in de Sitter space-time, then the stationary solutions exist, and initial field configurations tend with time to the stationary ones. However, there are no stationary solutions for $\delta_0\geq H^{−1}/\sqrt{2}$. We have calculated numerically the rate of the wall expansion in this case and have found that the width of the wall grows exponentially fast for $\delta_0\gg H^{−1}$. An explanation for the critical value $\delta_{0c}=H^{−1}/\sqrt{2}$ is also proposed.
I will discuss the Zee model, a radiative neutrino mass model with possible large lepton flavor violating Higgs (HLFV) decays, in particular $h\rightarrow \tau \mu$. In the first part I will analyse the effective operators responsible for HLFV and their tree level UV completions. By imposing constraints from charged lepton flavour violating observables, like $\tau \rightarrow \mu \gamma$, upper limits on BR$(h\rightarrow \tau \mu)$ can be set for the different realizations. In the second part of the talk, I will discuss the connection of HLFV to popular neutrino mass models. We will argue why most neutrino models generate very suppressed HLFV at one loop level. On the other hand, the general Zee model generates HLFV at tree level. We will present results of a full parameter scan which show how the model is fully testable by LHC and LFV searches.
We compare the sensitivity of precision measurements of lepton flavour observables to the reach of the LHC in a case study of lepton-flavour violating operators of dimension six with two leptons and two quarks, and operators of dimension eight with two leptons and two gluons. For light quarks precision measurements always yield the more stringent constraints. The LHC complements precision measurements for operators with heavier quarks. Stronger limits can already be set on the cutoff scale for operators with $\tau$ leptons with the LHC.
We report on a search for single-photon events in 53 fb−1 of e+e− collision data collected with the BABAR detector at the PEP-II B-factory. We look for events with a single high-energy photon and a large missing momentum and energy, consistent with production of a spin-1 particle A’ through the process e+e- -> gamma A’, A’ -> invisible. Such particles, referred to as “dark photons”, are motivated by theories applying a U(1) gauge symmetry to dark matter.
We find no evidence for such processes and set 90% confidence level upper limits on the coupling strength of A’ to e+e- for a dark photon with a mass lower than 8 GeV. In particular, our limits exclude the values of the A’ coupling suggested by the dark-photon interpretation of the muon (g-2) anomaly, as well as a broad range of parameters.
The total mass density of the Universe appears to be dominated by dark matter. However, beyond its gravitational interactions at the galactic scale, little is known about its nature. We have shown that a single optical atomic clock can be used as a detector for the hypothetical dark matter in the form of stable topological defects, for example, monopoles, strings or domain walls. We exploited differences in the susceptibilities to the fine-structure constant of essential parts of an optical atomic clock, i.e. the atoms and the cavity. We perform an experiment which constrained the strength of atomic coupling to hypothetical dark-matter cosmic objects. Under the conditions of our experiments, the degree of constraint was found to exceed the previously reported limits by more than three orders of magnitude.
We generalize the pseudo-Dirac dark matter (pDDM) model, already considered in the literature in the context of effective field theories. In particular, we consider a simplified model in which a heavy $Z'$-vector boson couples the Standard Model sector to a Dirac fermion whose mass eigenstates are slightly separated in mass, with separation $\Delta m$. The lightest eigenstate (of mass $m_1$) is stable, and then represents a natural candidate for dark matter. The heaviest one, on the other hand, is unstable and can leave a trace at colliders in the form of jet(s)+missing energy. The effective cross section for coannihilations, which determines the relic abundance of DM, can be related to the predictions for collider signatures, and these can be used together to fix several free parameters of the model. As a result, for specific efficiency cuts and luminosity, we provide excluded regions in the $(m_1,\Delta m)$ plane, due to the lack of any signal at LHC.
The Particle and astrophysical Xenon (PandaX) project is a series of xenon-based ultra-low background experiments in the China JinPing underground Laboratory (CJPL) targeting the unknown physics of dark matter and neutrinos. The first and second stage experiments (PandaX-I and II) both utilize dual-phase xenon time projection chamber (TPC) to carry out direct search for the dark matter particles. PandaX-II, a half-ton scale experiment, is currently under operation, and produced leading limits on dark matter-nucleon spin independent and spin dependent scattering cross sections in 2016. In this talk, I shall present an overview of the PandaX project and the results from the first data of the PandaX-II experiment.
The SABRE (Sodium Iodide with Active Background Rejection) experiment will search for an annually modulating signal from dark matter using an array of ultra-pure NaI(Tl) detectors surrounded by an active scintillator veto to further reduce the intrinsic background. The rate of interactions between DM particles and the detector is expected to modulate due to Earth’s changing velocity relative to the DM halo. The first phase of the experiment is the SABRE Proof of Principle (PoP), a single 5kg crystal detector operated in a liquid scintillator filled vessel at the Laboratori Nazionali del Gran Sasso (LNGS). The PoP installation is underway with the goal of running in 2017 and performing the first in situ measurement of the crystal background and testing the veto efficiency, thus validating the SABRE concept. GEANT4-based Monte Carlo simulations have been developed to estimate the background in the PoP. The most recent simulation is based on radio-purity measurements of the detector components and includes detailed versions of the detector part geometries. The second phase of SABRE will be twin arrays of NaI(Tl) detectors operating at LNGS and at the Stawell Underground Physics Laboratory (SUPL) in Australia. By locating detectors in both hemispheres, SABRE will minimize seasonal systematic effects. In this talk, the SABRE PoP activities at LNGS and results from the most recent Monte Carlo simulations will be presented.
Dual-phase time-projection chambers based on noble gases are a very efficient particle detection technology which leads the field of dark matter searches. The XENON collaboration aims at a direct detection of dark matter with experiments based on liquid xenon.
The current step of the research program, the XENON1T experiment, is fully operational since May 2016 and is currently acquiring data. It features 2t of liquid xenon in the target, the ~10m water tank for background reduction via Cherenkov muon veto, and an innovative system for gas storage, liquefaction and purification.
In this talk I will discuss the technological aspects of the XENON1T detector, summarise the status and detector performance, and present the results from the first science run.
EDELWEISS is an experiment dedicated to direct dark matter searches using high-purity germanium detectors equipped with a full charge and thermal signal readout. The detectors are operated at 18 mK in the underground laboratory of Modane, in the Frejus tunnel. Recent results on the spin-independent WIMP-nucleon cross-section for WIMP masses below 30 GeV for a fiducial exposure of 582kg.day will be shown. In addition, we present a measurement of the cosmogenic activation of tritium in germanium detectors, an important background to consider in searches for low-mass WIMPs. Technical developments to explore the region from 1 to 20 GeV will be presented as well.
Detecting Dark Matter (DM) particle is one of the most exciting experimental challenges of modern astroparticle physics. Many cosmological observations at different scales agree on the existence of DM ascribing 25$\%$ of the Universe's composition to it. In this context a variety of experiments have been performed in order to investigate the different possible DM candidates arising from theory.
The CRESST III experiment, located at the Gran Sasso underground laboratory in Italy, is designed to detect Dark Matter interactions in CaWO$_4$ scintillating crystals, probing the low mass region of the parameter space for spin-independent DM-nucleus scattering below $\sim$ 10 GeV/c$^2$ with a sensitivity never reached before.
In CRESST-III an array of 10 scintillating CaWO$_4$ crystals of $\sim$ 25 g each are read out simultaneously as cryogenic calorimeters and scintillating detectors. The scintillation light is measured with a second cryogenic calorimeter made of Silicon-On-Sapphire. Both cryogenic calorimeters of CRESST-III detectors are operated at temperatures below 10 mK and are equipped with Transition Edge Sensor (TES) thermometers for read-out.
The double channel read-out is foreseen for interacting particle identification used for background suppression. The TES sensors of the CaWO$_4$ crystals are designed to provide thresholds of the order of 50-100 eV.
Furthermore, the CRESST-III detectors modules are also equipped with a fully scintillating housing and instrumented holders to veto the possible background originated from surrounding surfaces.
Phase 1 of the CRESST-III experiment started data-taking in August 2016. In this contribution the current status and future perspectives of the CRESST-III experiment will be presented.