DOCSLIB.ORG

Measurement of the Muon Neutrino Charged Current Interactions and the Muon Neutrino Single Pion Cross Section on CH Using the T2K Near Detector

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Measurement of the Muon Neutrino Charged Current Interactions and the Muon Neutrino Single Pion Cross Section on CH Using the T2K Near Detector Universitat Autonoma` de Barcelona Doctoral Thesis Measurement of the Muon Neutrino Charged Current Interactions and the Muon Neutrino Single Pion Cross Section on CH Using the T2K Near Detector Supervisor: Dr. Federico Sanchez´ Nieto Author: Tutor: Raquel Castillo Fernandez´ Dr. Enrique Fernandez´ Sanchez´ A thesis submitted in fulfilment of the requirements for the degree of PhD on Physics in the Neutrino Group Institut de F´ısicad'Altes Energies (IFAE) June 2015 \No es sabio el que sabe donde est´ael tesoro, sino el que trabaja y lo saca." Francisco de Quevedo y Villegas UNIVERSITAT AUTONOMA` DE BARCELONA Abstract Facultat de Ci´encies Institut de F´ısicad'Altes Energies (IFAE) PhD on Physics Measurement of the Muon Neutrino Charged Current Interactions and the Muon Neutrino Single Pion Cross Section on CH Using the T2K Near Detector by Raquel Castillo Fernandez´ The T2K experiment is a long baseline neutrino experiment which utilizes an almost pure muon neutrino beam. The main goal of the experiment is the measurement of the oscillation parameters of the muon neutrinos. In order to achieve this goal, T2K requires an accurate prediction of the interaction rates in the far detector, Super{KamiokaNDE. The near detector of T2K, ND280, measures the interaction rates and estimates the number of events at the far detector. The muon neutrino charged current interactions in the near detector (ND280) are used to predict the rate at the far detector (Super{KamiokaNDE). To a better constrain of the cross section parameters, which are dominant in the analysis together with the flux uncertainty, we categorize the selected events in three different samples according to the number of pions in the final state. These categories allow for a better constrain of the oscillation signal channel (Charged Current Quasielastic) and the main oscillation background (Charged Current 1 Charged Pion). Current and future neutrino experiments are limited by neutrino cross section uncertain- ties. The actual cross section models are in tension with the experimental data in some energy ranges. It is still critical to study neutrino{nucleus cross sections on all possible interaction channels. The muon neutrino charged current single pion production is one of the main channels in tension with the model. As a second contribution, we present the measurement of the Charged Current single positive pion production cross section using a model independent approach exploring the full capability of the ND280 detector to determine the kinematical distributions of the event. The improved knowledge of the interactions, and in concrete for the single pion channel, will allow the reduction of the the systematical uncertainties in the oscillation analysis. Medida de las Interacciones de Neutrino Mu´onicode Corriente Cargada y Secci´onEficaz de Producci´onde un S´oloPi´onen Interacci´onde Neutrino Mu´onicode Corriente Cargada en CH usando el Detector Cercano de T2K por Raquel Castillo Fernandez´ El experimento T2K es un experimento de neutrinos de largo recorrido que utiliza un haz casi puro the neutrinos mu´onicos.El objetivo principal del experimento es a medida de los par´ametrosde oscilaci´ondel neutrino mu´onicos.Para conseguir ´esteobjetivo, T2K necesita una rigurosa predicci´ondel ´ındicede interacciones en el detector lejano, Super{ KamiokaNDE. El detector cercano de T2K, ND280, calcula el ´ındice de interacciones y estima el n´umerode eventos en el detector lejano. Las interacciones de neutrino mu´onicode corriente cargada en el detector cercano (ND280) son usadas para predecir el ´ındicede eventos en el detector lejano (Super{ KamiokaNDE). Para una mejor restricci´onde los par´ametrosde secci´oneficaz, los cuales dominan el an´alisisjunto con las incertezas de la prediccion del flujo, categorizamos los eventos seleccionados en tres grupos de acuerdo con el n´umerode piones en el estado final. Estas tres categor´ıaspermiten un mejor ajuste de la se~naldel canal de oscilaci´on (Corriente Cargada Quasiel´astica)y el principal ru´ıdoen ocilaciones (Corriente Cargada de 1 Pi´onCargado). Actuales y futuros experimentos de neutrinos est´anlimitados por las incertezas en las secciones eficaces de neutrinos. Los modelos actuales de secci´oneficaz est´anen tension con los datos experimentales en algunos rangos energ´eticos. Esto hace que sea critico estudiar secciones eficaces de neutrino{nucleo en todos los canales de interacci´onposibles. La producci´onthe un solo pi´onen interacciones de neutrino mu´onicode corriente cargada es uno de los principales canales en tensi´oncon los modelos. Como segunda contribuci´on, presentamos el c´alculode producci´onthe un solo pi´onen interacciones de neutrino mu´onicode corriente cargada usando un enfoque indepenediente del modelo explorando la capacidad total del detector ND280 para establecer las distribuciones cinem´aticasdel evento. La mejore del conocimiento de las interacciones, y en concreto del canal de producci´onde un s´olopi´on,permitir´ala reducci´onde las incertidumbres sistem´aticas en el an´alisisde oscilaciones. Acknowledgements First, I would like to thanks to Federico for the opportunity he gave me and all the disccussions we had during these four years. Each single discussion was important. I want to thanks as well Matteo and Ramon, previous and current IFAE's directors, thanks to take care of everybody! I would like to thanks the people who provide me support during my first years of research, Michela and Mike, thanks for your patiente! Thanks a lot to my convener among all the analysis, Francesca, for the patiente and all the support. I would like to thanks as well the rest of Cross Section Group conveners and specially to Kendall for her enthusiasm and motivation. Thanks to Martin, A.K.A \in potato", who was always providing support and very nice discussions during the cross section analysis. I would like to thanks specially to Alfons, who proposed to me to do the CC1π analysis during one of our jet{lag{discussions in that nice ryokan in Tokai. Thanks to the NIWG conveners and to the questioning sense of Kevin which make the analysis stronger. Thanks a lot to Michel and Sara which helped on the improvement of the work. And thanks to Stefania who read very carefully this thesis and make it easier to digest. Haig d'agrair molt especialment a Xavier Vinyas qui em va donar la primera oportunitat de treballar en recerca. Moltes gracies per la motivaci´o,pel carisma i per fer{me estimar la f´ısicanuclear. I want to thanks to all the T2K collaborators for all the nice time in this great experi- ment. And specially I would like to thanks to Jiae, Leila, Javi, Callum, Matt, Thomas, Sasha, Panos, Teppei, Denis, Lorena, Anselmo, Melody, Tianlu and Minoo, thanks a lot for the very nice time! Thanks to the IFAE people and especially to Gerard, Gianluca, J¨oern,Iv´anand Em- manuelle. Welcome to the new neutrino's IFAE members, Alfonso, Bruno and John! And specially thanks to Alfonso, it was so funny to work with you. Quiero agradecer a Irene, Sandrinha, Marta, Jose, Rafael, Miguel Angel, Roberto, Miguel, Roger y Carlos todos los buenos momentos en la UAB. Gracias por el gran sentido del humor. Me gustar´ıadedicar tambien esta tesis a Ana, nuestra mexicana loca y fuerte que siempre recordaremos. Vull agrair tot el suport i sentit del humor a l'Anna, Fran, Agnese, Noa, Nuri y Ana. Molt´ıssimesgr´acies!!! iv Pero sobretodo, quiero dar las las gracias a mi familia, mi madre, mi hermana Sara y Joaqu´ın.Sin vosotros esto no hubiera sido posible. Contents Abstract ii Acknowledgements iv List of Figures xi List of Tables xxi 1 Outline 1 2 Neutrino Physics 3 2.1 Historical Introduction ............................. 3 2.2 Neutrino Interactions .............................. 7 2.2.1 Neutrino-Nucleon scattering ...................... 7 2.2.1.1 Neutrino Charged Current Quasi-Elastic Interactions . 8 2.2.1.2 Neutrino Charged Current Single Pion production . 9 2.2.1.3 Nuclear Effects ........................ 16 2.2.1.4 When the Single Pion is Breaking Bad . 17 2.2.2 The neutrino Monte Carlo generator: NEUT . 18 2.2.2.1 Some other neutrino event Monte Carlo generator . 19 GENIE ............................. 19 NuWro .............................. 19 GiBUU ............................. 20 Some other neutrino interaction models . 20 3 T2K Long{Baseline Neutrino Oscillation Experiment 21 3.1 The T2K Neutrino Beam ........................... 22 3.1.1 The Proton Beam Accelerator Complex . 23 3.1.1.1 Primary Neutrino Beamline . 24 3.1.1.2 Secondary Neutrino Beamline . 25 3.1.2 The Off–Axis Configuration ...................... 27 3.1.3 The Neutrino Beam Composition ................... 29 3.1.3.1 The Neutrino Flux Prediction . 30 3.1.3.2 The NA61/SHINE Experiment . 31 3.2 The Near Detector Complex .......................... 32 vi Contents vii 3.2.1 The Off–Axis Detector: ND280 .................... 34 3.2.2 The UA1/NOMAD magnet ...................... 36 3.2.3 The Side Muon Range Detector (SMRD) . 36 3.2.4 The Electromagnetic Calorimeter (ECal) . 37 The ECal particle identification . 38 3.2.5 The π0 detector (P;D) ......................... 38 3.2.6 The Time Projection Chambers (TPCs) . 40 The TPC particle identification . 42 3.2.7 The Fine Grain Detectors (FGDs) . 44 3.2.7.1 The FGD PID ........................ 45 3.3 The far detector: SuperKamiaokaNDE .................... 46 4 Detector Systematical Uncertainties and Propagation 49 4.1 ND280 Detector Systematics ......................... 49 4.1.1 TPC Particle ID ............................ 50 4.1.2 TPC cluster efficiency ......................... 51 4.1.3 TPC single and double track–finding efficiency . 52 4.1.4 TPC momentum resolution ...................... 52 4.1.5 TPC charge confusion ......................... 52 4.1.6 Track \Ubermerging"¨ ........................ 53 4.1.7 TPC field distortions .......................... 53 4.1.8 TPC Momentum Scale ......................... 53 4.1.9 FGD-only track efficiency ....................... 54 4.1.10 FGD-only track PID .........................
Load more

Recommended publications
  • The Particle World
    The Particle World ² What is our Universe made of? This talk: ² Where does it come from? ² particles as we understand them now ² Why does it behave the way it does? (the Standard Model) Particle physics tries to answer these ² prepare you for the exercise questions. Later: future of particle physics. JMF Southampton Masterclass 22–23 Mar 2004 1/26 Beginning of the 20th century: atoms have a nucleus and a surrounding cloud of electrons. The electrons are responsible for almost all behaviour of matter: ² emission of light ² electricity and magnetism ² electronics ² chemistry ² mechanical properties . technology. JMF Southampton Masterclass 22–23 Mar 2004 2/26 Nucleus at the centre of the atom: tiny Subsequently, particle physicists have yet contains almost all the mass of the discovered four more types of quark, two atom. Yet, it’s composite, made up of more pairs of heavier copies of the up protons and neutrons (or nucleons). and down: Open up a nucleon . it contains ² c or charm quark, charge +2=3 quarks. ² s or strange quark, charge ¡1=3 Normal matter can be understood with ² t or top quark, charge +2=3 just two types of quark. ² b or bottom quark, charge ¡1=3 ² + u or up quark, charge 2=3 Existed only in the early stages of the ² ¡ d or down quark, charge 1=3 universe and nowadays created in high energy physics experiments. JMF Southampton Masterclass 22–23 Mar 2004 3/26 But this is not all. The electron has a friend the electron-neutrino, ºe. Needed to ensure energy and momentum are conserved in ¯-decay: ¡ n ! p + e + º¯e Neutrino: no electric charge, (almost) no mass, hardly interacts at all.
    [Show full text]
  • The Story of Large Electron Positron Collider 1
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Publications of the IAS Fellows GENERAL ç ARTICLE The Story of Large Electron Positron Collider 1. Fundamental Constituents of Matter S N Ganguli I nt roduct ion The story of the large electron positron collider, in short LEP, is linked intimately with our understanding of na- ture'sfundamental particlesand theforcesbetween them. We begin our story by giving a brief account of three great discoveries that completely changed our thinking Som Ganguli is at the Tata Institute of Fundamental and started a new ¯eld we now call particle physics. Research, Mumbai. He is These discoveries took place in less than three years currently participating in an during 1895 to 1897: discovery of X-rays by Wilhelm experiment under prepara- Roentgen in 1895, discovery of radioactivity by Henri tion for the Large Hadron Becquerel in 1896 and the identi¯cation of cathode rays Collider (LHC) at CERN, Geneva. He has been as electrons, a fundamental constituent of atom by J J studying properties of Z and Thomson in 1897. It goes without saying that these dis- W bosons produced in coveries were rewarded by giving Nobel Prizes in 1901, electron-positron collisions 1903 and 1906, respectively. X-rays have provided one at the Large Electron of the most powerful tools for investigating the struc- Positron Collider (LEP). During 1970s and early ture of matter, in particular the study of molecules and 1980s he was studying crystals; it is also an indispensable tool in medical diag- production and decay nosis.
    [Show full text]
  • 12 from Neutral Currents to Weak Vector Bosons
    12 From neutral currents to weak vector bosons The unification of weak and electromagnetic interactions, 1973{1987 Fermi's theory of weak interactions survived nearly unaltered over the years. Its basic structure was slightly modified by the addition of Gamow-Teller terms and finally by the determination of the V-A form, but its essence as a four fermion interaction remained. Fermi's original insight was based on the analogy with elec- tromagnetism; from the start it was clear that there might be vector particles transmitting the weak force the way the photon transmits the electromagnetic force. Since the weak interaction was of short range, the vector particle would have to be heavy, and since beta decay changed nuclear charge, the particle would have to carry charge. The weak (or W) boson was the object of many searches. No evidence of the W boson was found in the mass region up to 20 GeV. The V-A theory, which was equivalent to a theory with a very heavy W , was a satisfactory description of all weak interaction data. Nevertheless, it was clear that the theory was not complete. As described in Chapter 6, it predicted cross sections at very high energies that violated unitarity, the basic principle that says that the probability for an individual process to occur must be less than or equal to unity. A consequence of unitarity is that the total cross section for a process with 2 angular momentum J can never exceed 4π(2J + 1)=pcm. However, we have seen that neutrino cross sections grow linearly with increasing center of mass energy.
    [Show full text]
  • The Standard Model Part II: Charged Current Weak Interactions I
    Prepared for submission to JHEP The Standard Model Part II: Charged Current weak interactions I Keith Hamiltona aDepartment of Physics and Astronomy, University College London, London, WC1E 6BT, UK E-mail: [email protected] Abstract: Rough notes on ... Introduction • Relation between G and g • F W Leptonic CC processes, ⌫e− scattering • Estimated time: 3 hours ⇠ Contents 1 Charged current weak interactions 1 1.1 Introduction 1 1.2 Leptonic charge current process 9 1 Charged current weak interactions 1.1 Introduction Back in the early 1930’s we physicists were puzzled by nuclear decay. • – In particular, the nucleus was observed to decay into a nucleus with the same mass number (A A) and one atomic number higher (Z Z + 1), and an emitted electron. ! ! – In such a two-body decay the energy of the electron in the decay rest frame is constrained by energy-momentum conservation alone to have a unique value. – However, it was observed to have a continuous range of values. In 1930 Pauli first introduced the neutrino as a way to explain the observed continuous energy • spectrum of the electron emitted in nuclear beta decay – Pauli was proposing that the decay was not two-body but three-body and that one of the three decay products was simply able to evade detection. To satisfy the history police • – We point out that when Pauli first proposed this mechanism the neutron had not yet been discovered and so Pauli had in fact named the third mystery particle a ‘neutron’. – The neutron was discovered two years later by Chadwick (for which he was awarded the Nobel Prize shortly afterwards in 1935).
    [Show full text]
  • First Determination of the Electric Charge of the Top Quark
    First Determination of the Electric Charge of the Top Quark PER HANSSON arXiv:hep-ex/0702004v1 1 Feb 2007 Licentiate Thesis Stockholm, Sweden 2006 Licentiate Thesis First Determination of the Electric Charge of the Top Quark Per Hansson Particle and Astroparticle Physics, Department of Physics Royal Institute of Technology, SE-106 91 Stockholm, Sweden Stockholm, Sweden 2006 Cover illustration: View of a top quark pair event with an electron and four jets in the final state. Image by DØ Collaboration. Akademisk avhandling som med tillst˚and av Kungliga Tekniska H¨ogskolan i Stock- holm framl¨agges till offentlig granskning f¨or avl¨aggande av filosofie licentiatexamen fredagen den 24 november 2006 14.00 i sal FB54, AlbaNova Universitets Center, KTH Partikel- och Astropartikelfysik, Roslagstullsbacken 21, Stockholm. Avhandlingen f¨orsvaras p˚aengelska. ISBN 91-7178-493-4 TRITA-FYS 2006:69 ISSN 0280-316X ISRN KTH/FYS/--06:69--SE c Per Hansson, Oct 2006 Printed by Universitetsservice US AB 2006 Abstract In this thesis, the first determination of the electric charge of the top quark is presented using 370 pb−1 of data recorded by the DØ detector at the Fermilab Tevatron accelerator. tt¯ events are selected with one isolated electron or muon and at least four jets out of which two are b-tagged by reconstruction of a secondary decay vertex (SVT). The method is based on the discrimination between b- and ¯b-quark jets using a jet charge algorithm applied to SVT-tagged jets. A method to calibrate the jet charge algorithm with data is developed. A constrained kinematic fit is performed to associate the W bosons to the correct b-quark jets in the event and extract the top quark electric charge.
    [Show full text]
  • Muon Neutrino Mass Without Oscillations
    The Distant Possibility of Using a High-Luminosity Muon Source to Measure the Mass of the Neutrino Independent of Flavor Oscillations By John Michael Williams [email protected] Markanix Co. P. O. Box 2697 Redwood City, CA 94064 2001 February 19 (v. 1.02) Abstract: Short-baseline calculations reveal that if the neutrino were massive, it would show a beautifully structured spectrum in the energy difference between storage ring and detector; however, this spectrum seems beyond current experimental reach. An interval-timing paradigm would not seem feasible in a short-baseline experiment; however, interval timing on an Earth-Moon long baseline experiment might be able to improve current upper limits on the neutrino mass. Introduction After the Kamiokande and IMB proton-decay detectors unexpectedly recorded neutrinos (probably electron antineutrinos) arriving from the 1987A supernova, a plethora of papers issued on how to use this happy event to estimate the mass of the neutrino. Many of the estimates based on these data put an upper limit on the mass of the electron neutrino of perhaps 10 eV c2 [1]. When Super-Kamiokande and other instruments confirmed the apparent deficit in electron neutrinos from the Sun, and when a deficit in atmospheric muon- neutrinos likewise was observed, this prompted the extension of the kaon-oscillation theory to neutrinos, culminating in a flavor-oscillation theory based by analogy on the CKM quark mixing matrix. The oscillation theory was sensitive enough to provide evidence of a neutrino mass, even given the low statistics available at the largest instruments. J. M. Williams Neutrino Mass Without Oscillations (2001-02-19) 2 However, there is reason to doubt that the CKM analysis validly can be applied physically over the long, nonvirtual propagation distances of neutrinos [2].
    [Show full text]
  • PSI Muon-Neutrino and Pion Masses
    Around the Laboratories More penguins. The CLEO detector at Cornell's CESR electron-positron collider reveals a clear excess signal of photons from rare B particle decays, once the parent upsilon 4S resonance has been taken into account. The convincing curve is the theoretically predicted spectrum. could be at the root of the symmetry breaking mechanism which drives the Standard Model. PSI Muon-neutrino and pion masses wo experiments at the Swiss T Paul Scherrer Institute (PSI) in Villigen have recently led to more precise values for two important physics quantities - the masses of the muon-type neutrino and of the charged pion. The first of these experiments - B. Jeckelmann et al. (Fribourg Univer­ sity, ETH and Eidgenoessisches Amt fuer Messwesen) was originally done about a decade ago. To fix the negative-pion mass, a high-precision crystal spectrometer measured the energy of the X-rays emitted in the 4f-3d transition of pionic magnesium atoms. The result (JECKELMANN 86 in the graph, page 16), with smaller seen in neutral kaon decay. can emerge. Drawing physics conclu­ errors than previous charged-pion CP violation - the disregard at the sions from the K* example was mass measurements, dominated the few per mil level of a invariance of therefore difficult. world average. physics with respect to a simultane­ Now the CLEO group has collected In view of more recent measure­ ous left-right reversal and particle- all such events producing a photon ments on pionic magnesium, a re- antiparticle switch - has been known with energy between 2.2 and 2.7 analysis shows that the measured X- for thirty years.
    [Show full text]
  • Charged Current Anti-Neutrino Interactions in the Nd280 Detector
    CHARGED CURRENT ANTI-NEUTRINO INTERACTIONS IN THE ND280 DETECTOR BRYAN E. BARNHART HIGH ENERGY PHYSICS UNIVERSITY OF COLORADO AT BOULDER ADVISOR: ALYSIA MARINO Abstract. For the neutrino beamline oscillation experiment Tokai to Kamioka, the beam is clas- sified before oscillation by the near detector complex. The detector is used to measure the flux of different particles through the detector, and compare them to Monte Carlo Simulations. For this work, theν ¯µ background of the detector was isolated by examining the Monte Carlo simulation and determining cuts which removed unwanted particles. Then, a selection of the data from the near detector complex underwent the same cuts, and compared to the Monte Carlo to determine if the Monte Carlo represented the data distribution accurately. The data was found to be consistent with the Monte Carlo Simulation. Date: November 11, 2013. 1 Bryan E. Barnhart University of Colorado at Boulder Advisor: Alysia Marino Contents 1. The Standard Model and Neutrinos 4 1.1. Bosons 4 1.2. Fermions 5 1.3. Quarks and the Strong Force 5 1.4. Leptons and the Weak Force 6 1.5. Neutrino Oscillations 7 1.6. The Relative Neutrino Mass Scale 8 1.7. Neutrino Helicity and Anti-Neutrinos 9 2. The Tokai to Kamioka Experiment 9 2.1. Japan Proton Accelerator Research Complex 10 2.2. The Near Detector Complex 12 2.3. The Super-Kamiokande Detector 17 3. Isolation of the Anti-Neutrino Component of Neutrino Beam 19 3.1. Experiment details 19 3.2. Selection Cuts 20 4. Cut Descriptions 20 4.1. Beam Data Quality 20 4.2.
    [Show full text]
  • Neutrino Vs Antineutrino Lepton Number Splitting
    Introduction to Elementary Particle Physics. Note 18 Page 1 of 5 Neutrino vs antineutrino Neutrino is a neutral particle—a legitimate question: are neutrino and anti-neutrino the same particle? Compare: photon is its own antiparticle, π0 is its own antiparticle, neutron and antineutron are different particles. Dirac neutrino : If the answer is different , neutrino is to be called Dirac neutrino Majorana neutrino : If the answer is the same , neutrino is to be called Majorana neutrino 1959 Davis and Harmer conducted an experiment to see whether there is a reaction ν + n → p + e - could occur. The reaction and technique they used, ν + 37 Cl e- + 37 Ar, was proposed by B. Pontecorvo in 1946. The result was negative 1… Lepton number However, this was not unexpected: 1953 Konopinski and Mahmoud introduced a notion of lepton number L that must be conserved in reactions : • electron, muon, neutrino have L = +1 • anti-electron, anti-muon, anti-neutrino have L = –1 This new ad hoc law would explain many facts: • decay of neutron with anti-neutrino is OK: n → p e -ν L=0 → L = 1 + (–1) = 0 • pion decays with single neutrino or anti-neutrino is OK π → µ-ν L=0 → L = 1 + (–1) = 0 • but no pion decays into a muon and photon π- → µ- γ, which would require: L= 0 → L = 1 + 0 = 1 • no decays of muon with one neutrino µ- → e - ν, which would require: L= 1 → L = 1 ± 1 = 0 or 2 • no processes searched for by Davis and Harmer, which would require: L= (–1)+0 → L = 0 + 1 = 1 But why there are no decays µµµ →→→ e γγγ ? 2 Splitting lepton numbers 1959 Bruno Pontecorvo
    [Show full text]
  • Neutrino-Electron Scattering: General Constraints on Z 0 and Dark Photon Models
    Neutrino-Electron Scattering: General Constraints on Z 0 and Dark Photon Models Manfred Lindner,a Farinaldo S. Queiroz,b Werner Rodejohann,a Xun-Jie Xua aMax-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany bInternational Institute of Physics, Federal University of Rio Grande do Norte, Campus Univer- sitário, Lagoa Nova, Natal-RN 59078-970, Brazil E-mail: [email protected], [email protected], [email protected], [email protected] Abstract. We study the framework of U(1)X models with kinetic mixing and/or mass mixing terms. We give general and exact analytic formulas and derive limits on a variety of U(1)X models that induce new physics contributions to neutrino-electron scattering, taking into account interference between the new physics and Standard Model contributions. Data from TEXONO, CHARM-II and GEMMA are analyzed and shown to be complementary to each other to provide the most restrictive bounds on masses of the new vector bosons. In particular, we demonstrate the validity of our results to dark photon-like as well as light Z0 models. arXiv:1803.00060v1 [hep-ph] 28 Feb 2018 Contents 1 Introduction 1 2 General U(1)X Models2 3 Neutrino-Electron Scattering in U(1)X Models7 4 Data Fitting 10 5 Bounds 13 6 Conclusion 16 A Gauge Boson Mass Generation 16 B Cross Sections of Neutrino-Electron Scattering 18 C Partial Cross Section 23 1 Introduction The Standard Model provides an elegant and successful explanation to the electroweak and strong interactions in nature [1].
    [Show full text]
  • Θc Βct Ct N Particle Nβ 1 Nv C
    SectionSection XX TheThe StandardStandard ModelModel andand BeyondBeyond The Top Quark The Standard Model predicts the existence of the TOP quark ⎛ u ⎞ ⎛c⎞ ⎛ t ⎞ + 2 3e ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎝d ⎠ ⎝ s⎠ ⎝b⎠ −1 3 e which is required to explain a number of observations. Example: Absence of the decay K 0 → µ+ µ− W − d µ − 0 0 + − −9 K u,c,t + ν B(K → µ µ )<10 W µ s µ + The top quark cancels the contributions from the u, c quarks. Example: Electromagnetic anomalies This diagram leads to infinities in the f γ theory unless Q = 0 γ f ∑ f f f γ where the sum is over all fermions (and colours) 2 1 ∑Q f = []3×()−1 + []3×3× 3 + [3×3×(− 3 )]= 0 244 f 0 At LEP, mt too heavy for Z → t t or W → tb However, measurements of MZ, MW, ΓZ and ΓW are sensitive to the existence of virtual top quarks b t t t W + W + Z 0 Z 0 Z 0 W t b t b Example: Standard Model prediction Also depends on the Higgs mass 245 The top quark was discovered in 1994 by the CDF experiment at the worlds highest energy p p collider ( s = 1 . 8 TeV ), the Tevatron at Fermilab, US. q b Final state W +W −bb g t W + Mass reconstructed in a − t W similar manner to MW at q LEP, i.e. measure jet/lepton b energies/momenta. mtop = (178 ± 4.3) GeV Most recent result 2005 246 The Standard Model c. 2006 MATTER: Point-like spin ½ Dirac fermions.
    [Show full text]
  • The Weak Interaction
    The Weak Interaction April 20, 2016 Contents 1 Introduction 2 2 The Weak Interaction 2 2.1 The 4-point Interaction . .3 2.2 Weak Propagator . .4 3 Parity Violation 5 3.1 Parity and The Parity Operator . .5 3.2 Parity Violation . .6 3.3 CP Violation . .7 3.4 Building it into the theory - the V-A Interaction . .8 3.5 The V-A Interaction and Neutrinos . 10 4 What you should know 11 5 Furthur reading 11 1 1 Introduction The nuclear β-decay caused a great deal of anxiety among physicists. Both α- and γ-rays are emitted with discrete spectra, simply because of energy conservation. The energy of the emitted particle is the same as the energy difference between the initial and final state of the nucleus. It was much more difficult to see what was going on with the β-decay, the emission of electrons from nuclei. Chadwick once reported that the energy spectrum of electrons is continuous. The energy could take any value between 0 and a certain maximum value. This observation was so bizarre that many more experiments followed up. In fact, Otto Han and Lise Meitner, credited for their discovery of nuclear fission, studied the spectrum and claimed that it was discrete. They argued that the spectrum may appear continuous because the electrons can easily lose energy by breamsstrahlung in material. The maximum energy observed is the correct discrete spectrum, and we see lower energies because of the energy loss. The controversy went on over a decade. In the end a definitive experiment was done by Ellis and Wooseley using a very simple idea.
    [Show full text]