NuShock

NuShock is a flexible framework to study the phenomenology of models with heavy neutrinos. Given some description of the physics processes (cross-sections or decay rates), the neutrino flux, and the detector geometry, it is possible to study the sensitivity to a specific process of a neutrino experiment. Tools for background estimations are also available.

Installation

Requirments

• make
• C++11 compiler
• cuba
• LHAPDF
• ROOT

Set the variables:

• $CUBA to point to the installation path for cuba
• $LHAPDF to point to the installation path for LHAPDF
• $ROOTSYS to point to the installation path for ROOT (this already part of the installation process)

If ROOT is properly set, root-config should be in the user's $PATH and so the Makefile can find the includes and libraries on its own. Remember to update your $LD_LIBRARY_PATH.

Compilation

Simply doing

make

is enough. This will create binaries in the bin folder.

WARNING: this readme is deprecated and will be updated soon!

Usage of the framework

The main functions are to be placed in the app/ folder and the exectuables are moved to the bin/ folder after compilation. These are, at the moment

Configuration files

Most of the classes, like flux or detector, use description files contained in the config/ subfolder.

The detector configuration, for example config/detectro.card describes the DUNE near detector, composed of two parts: a LArTPC and a FGT. Sizes and dimensions are desribed in the file, whereas the tracking resolutions are in config/resolution.card. At the end there is a list of efficiency files, used to estimate sensitivty including background.

More description inside the configuration file itself.

At the moment the detector class expects a detector made of two parts: a LArTPC in front of a TPC, but this problem can be overcome by defining a null secondary detector. The geometry are boxes, so this should be maybe changed. In the Tracker class, correct material properties should be defined, like interaction length etc. At the moment olny liquid argon, gaseous argon, iron and lead are defined. Material description is important for energy loss in material: the length of the track defines the resolution to use, if it is a contained track or not. In the case of DUNE ND, a track is contained if 80% of the total length are inside. This can be changed with the Containment entry in the config file.

The flux configuration files expects paths to ROOT files containing TH1D with the fluxes. As an extra, modifier files for tau flux, created from direct simulation of HNL production from Ds decays.

Flux

The flux package has a matrioska-like structure. The lowest level class is Flux which copies to memory TH1D from flux configuration file. Above that the Driver class takes care of scaling the light-nu fluxes to HNL fluxes. The better way to use the Driver class is with the Engine class, which binds flux, detector and neutrino (HNL) type together to evaluate the flux AT the ND site and therefore evaluation of number of events is easy.

The number of events formula is split in two parts: flux+energy integration and probability+efficiency. The latter is done in the Detector class (see below). The flux and integration over energy E is handled by Engine which calls the Detector at each energy to estimate the probability+efficiency of an HNL of given energy E to decay inside the ND.

Physics

This is the most important package, in which all decay widths and distributions are compute. It is based on a base class, Amplitude, which has definition of the Feynman amplitudes, M2, of all decay and production modes taken in consideration. The Amplitude class is never called alone, but it is accesed by derived classes:

• DecayRates for computing decay rates and branching ratios
• Production for computing production scale factors
• PhaseSpace to be used for simulation of decays and production

The derived classes are best implemented in the Neutrino class, which in turn is derived from the Particle class (tools.h package). A neutrino object can be constructed on the stack as it doesn't require much memory and has methods that returns decay widths, branching ratios, scale factors, phase space generation, etc. When constructing a neutrion object, options can be passed to specify helicity and fermionic nature. The options are

• Neutrino::Left for a left-helicity particle
• Neutrino::Right for a right-helicity particle
• Neutrino::Unpolarised for an unpolarised particle, so information on helicity is integrated
• Neutrino::Dirac for a Dirac HNL
• Neutrino::Majorana for a Majorana HNL
• Neutrino::Antiparticle for an anti HNL; it makes sense only if HNL is Dirac

It the Antiparticle option is not specified, then the HNL is a particle by default.

In order to call a specific prodution or decay mode, a unique string is passed that identifies the channel of interest.

These strings are for decay channels:

• nnn for 3-body decay into 3 light neutrinos
• nGAMMA for radiative decay into a neutrino and a gamma (deprecated now)
• nEE for 3-body decay into nu e e
• nEM for 3-body decay into nu e mu
• nMM for 3-body decay into nu mu mu
• nET for 3-body decay into nu e tau
• nMT for 3-body decay into nu mu tau
• nPI0 for 2-body decay into nu pion0
• EPI for 2-body decay into e pion
• MPI for 2-body decay into mu pion
• TPI for 2-body decay into tau pion
• EKA for 2-body decay into e kaon
• MKA for 2-body decay into mu kaon
• nRHO0 for 2-body decay into nu rho0
• ERHO for 2-body decay into e rho
• MRHO for 2-body decay into mu rho
• EKAx for 2-body decay into e kaon*
• MKAx for 2-body decay into mu kaon*
• nOMEGA for 2-body decay into nu omega
• nETA for 2-body decay into nu eta
• nETAi for 2-body decay into nu eta'
• nPHI for 2-body decay into nu phi
• ECHARM for 2-body decay into e D (charm meson)
• ExpALL for decay with good discovery sensitivity (nEE, nEM, nMM, nPI0, EPI, MPI)

These strings are for production channels:

• MuonE for 3-body production from muon via Ue mixing
• MuonM for 3-body production from muon via Um mixing
• TauEE for 3-body production from tau to electron via Ue mixing
• TauET for 3-body production from tau to electron via Ut mixing
• TauMM for 3-body production from tau to muon via Um mixing
• TauMT for 3-body production from tau to muon via Ut mixing
• TauPI for 2-body production from tau to pion
• Tau2PI for 3-body production from tau to 2 pions (only phase space!)
• PionE for 2-body production from pion to electron
• PionM for 2-body production from pion to muon
• KaonE for 2-body production from kaon to electron
• KaonM for 2-body production from kaon to muon
• CharmE for 2-body production from D (charm) to electron
• CharmM for 2-body production from D (charm) to muon
• CharmT for 2-body production from D (charm) to tau
• Kaon0E for 3-body production from kaon0 to pion electron
• Kaon0M for 3-body production from kaon0 to pion muon
• KaonCE for 3-body production from kaon to pion0 electron
• KaonCM for 3-body production from kaon to pion0 muon

Detector

The Detector class loads geometry from configuration file. There are also a Tracker and Efficiency class, derived from Detector, to deal with background generation/smearing and detector efficiency computation.

Examples

The executables for production scale and decay branch can be run as

./bin/DecayBranch -o outputfile1 -c nEM -E 1.0 -M 0.5
./bin/ProductionScale -o outputfile2 -c Kaon0E -E 1.0 -M 0.5

The output files will contain two columns: the first ones being mass of HNL and the second ones the branching ratio of the decay of HNL into nEM and production scale factor for Kaon0E with mixing ratio 2:1:0.

Another example

./bin/Sensitivity -d config/ND_Full_2 -f config/FluxConfig -c EPI -E -o output
./bin/Sensitivity -d config/ND_Full_2 -f config/FluxConfig -c MPI -M -o output

which compute the experimental sensitivity to the channels EPI and MPI for zero background expectation. The lines are computed using bisection search method implemented in the Exclusion class from the analysis package.