A postulated law for the masses of the elementary particles
Postulated law for masses of elementary particles
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Physics at the MeV-Scale in Liquid Argon Time Projection Chambers
The liquid argon time projection chamber (LArTPC) is the detection technology chosen for several Fermilab-based neutrino experiments. This technology will be used in studies of neutrino cross-sections and oscillations, neutrinos from supernovae as well as a variety of studies of beyond the Standard Model physics. This thesis explores the use of these detectors to study MeV-scale activity. MeV-scale electrons arising from Compton scatters of deexcitation photons and photons from inelastic neutron scattering in neutrino-nucleus interactions are reconstructed using novel methods presented here. This work represents the first demonstration of MeV-scale physics capabilities in a LArTPC neutrino experiment as well as the first observation of neutrino-produced photons from nuclear de-excitation and inelastic neutron scattering. A search for millicharged particles, postulated by theories of beyond the standard model physics, is also performed using data from a LArTPC and the low-ener gy reconstruction techniques developed. The results set world-leading bounds on the parameter space of millicharged particles. The work in this thesis demonstrates that studies of MeV-scale activity and new physics are possible with LArTPC technology and provides the foundation for future LArTPC studies of low energy neutrinos and new physics.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Consequences of the Breakout Model for Particle Acceleration in CMEs and Flares
The largest and most efficient particle accelerators in the solar system are the giant events consisting of a fast coronal mass ejection (CME) and an intense X-class solar flare. Both flares and CMEs can produce l0(exp 32) ergs or more in nonthermal particles. Two general processes are believed to be responsible: particle acceleration at the strong shock ahead of the CME, and reconnection-driven acceleration in the flare current sheet. Although shock acceleration is relatively well understood, the mechanism by which flare reconnection produces nonthermal particles is still an issue of great debate. We address the question of CME/flare particle acceleration in the context of the breakout model using 2.5D MHD simulations with adaptive mesh refinement (AMR). The AMR capability allows us to achieve ultra-high numerical resolution and, thereby, determine the detailed structure and dynamics of the flare reconnection region. Furthermore, we employ newly developed numerical analysis tools for identifying and characterizing magnetic nulls, so that we can quantify accurately the number and location of magnetic islands during reconnection. Our calculations show that flare reconnection is dominated by the formation of magnetic islands. In agreement with many other studies, we find that the number of islands scales with the effective Lundquist number. This result supports the recent work by Drake and co-workers that postulates particle acceleration by magnetic islands. On the other hand, our calculations also show that the flare reconnection region is populated by numerous shocks and other indicators of strong turbulence, which can also accelerate particles. We discuss the implications of our calculations for the flare particle acceleration mechanism and for observational tests of the models.
Antiochos, S. K.↗
Limits on Stellar-Mass Compact Objects as Dark Matter from Gravitational Lensing of Type Ia Supernovae
We present that the nature of dark matter (DM) remains unknown despite very precise knowledge of its abundance in the Universe. An alternative to new elementary particles postulates DM as made of macroscopic compact halo objects (MACHO) such as black holes formed in the very early Universe. Stellar-mass primordial black holes (PBHs) are subject to less robust constraints than other mass ranges and might be connected to gravitational-wave signals detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO). New methods are therefore necessary to constrain the viability of compact objects as a DM candidate. Here we report bounds on the abundance of compact objects from gravitational lensing of type Ia supernovae (SNe). Current SNe data sets constrain compact objects to represent less than 35.2% (Joint Lightcurve Analysis) and 37.2% (Union 2.1) of the total matter content in the Universe, at 95% confidence level. The results are valid for masses larger than ~ 0.01 M ⊙ (solar masses), limited by the size SNe relative to the lens Einstein radius. We demonstrate the mass range of the constraints by computing magnification probabilities for realistic SNe sizes and different values of the PBH mass. Our bounds are sensitive to the total abundance of compact objects with M ≳ 0.01 M ⊙ and complementary to other observational tests. These results are robust against cosmological parameters, outlier rejection, correlated noise, and selection bias. PBHs and other MACHOs are therefore ruled out as the dominant form of DM for objects associated to LIGO gravitational wave detections. Lastly, these bounds constrain early-Universe models that predict stellar-mass PBH production and strengthen the case for lighter forms of DM, including new elementary particles.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Gauge mediation to effective supersymmetry through U(1)s with a dynamical supersymmetry breaking, and string compactification
We investigate the possibility of U(1){sup '} mediation, leading to an effective SUSY where the first two family sfermions are above 100 TeV but the third family sfermions and the Higgs doublets are in the TeV region (or the light stop (t-tilde{sub l}) case). The U(1)' gaugino, Zprimino (Z'-ino), needs not to be at a TeV scale, but needs to be somewhat lighter than the messenger scale. We consider two cases, one the mediation is only through U(1){sup '} and the other through U(1)' and the electroweak hypercharge U(1){sub Y}. In the SUSY field theory framework, we calculate the superpartner mass spectra for these two cases. We also point out that the particle species needed for these mechanisms are already obtained from a Z{sub 12-I} orbifold compactification.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
New color-octet axial vector boson revisited
In this paper we reexamine how to utilize the previous proposed color-octet axial-vector boson Z{sub C} to explain the 3.4{sigma} anomaly of tt forward-backward (FB) asymmetry A{sub FB} for m{sub tt}>450 GeV observed by CDF. Our numerical results indicate that the best-fit parameters are g{sub A}{sup q}=0.07, g{sub A}{sup Q}=3, and M{sub C}=440 GeV, which are obtained by fitting the mass dependent A{sub FB} and total cross section data provided by a recent CDF measurement. Here g{sub A}{sup q}(g{sub A}{sup Q}) and M{sub C} are the axial couplings among Z{sub C} with the first two (the third) generation quarks, and Z{sub C} mass, respectively. We also calculate one-side forward-backward asymmetry A{sub OFB} for top and bottom quark pair production at the LHC, focusing on the new contributions from Z{sub C}. Our studies show that A{sub OFB} can be utilized to measure the properties of new particle Z{sub C}.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Minimal 3-3-1 model with only two Higgs triplets
The simplest non-Abelian gauge extension of the electroweak standard model, the SU(3){sub c} x SU(3){sub L} x U(1){sub N}, known as the 3-3-1 model, has a minimal version which demands the least possible fermionic content to account for the whole established phenomenology for the well-known particles and interactions. Nevertheless, in its original form the minimal 3-3-1 model was proposed with a set of three scalar triplets and one sextet in order to yield the spontaneous breaking of the gauge symmetry and generate the observed fermion masses. Such a huge scalar sector turns the task of clearly identifying the physical scalar spectrum into a clumsy labor. It not only adds an obstacle for the development of its phenomenology, but implies a scalar potential plagued with new free coupling constants. In this work, we show that the framework of the minimal 3-3-1 model can be built with only two scalar triplets, but still triggering the desired pattern of spontaneous symmetry breaking and generating the correct fermion masses. We present the exact physical spectrum and also show all the interactions involving the scalars, obtaining a neat minimal 3-3-1 model far more suited for phenomenological studies at the current Large Hadron Collider.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
First Charge-Exchange Measurements with SHARAQ
The isovector spin monopole resonances (IVSMR) of the {beta}{sup +} type were observed for the first time in the {sup 208}Pb and {sup 90}Zr(t,{sup 3}He) reactions at 300 MeV/u. The experiment was performed at the RI Beam Factory (RIBF) at RIKEN by using the newly-constructed magnetic spectrometer SHARAQ. The double differential cross sections for the {sup 208}Pb and {sup 90}Zr(t,{sup 3}He) reactions were obtained at the excitation energy of 0{<=}E{sub x}{<=}70 MeV and the scattering angles of 0 deg. {<=}{theta}{<=}3 deg. The monopole component was identified by making a difference between the zero-degree and backward-angle spectra. The signatures of the IVSMR are observed at an excitation energy of 12 MeV(20 MeV) in {sup 208}Pb({sup 90}Zr)(t,{sup 3}He) reaction, which agrees fairly well with the theoretical predictions.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Structure of Neutron-rich Calcium Isotopes and Roles of Three-body Interaction
Structure of neutron-rich calcium isotopes are studied by shell model calculations with the inclusion of three-body interactions. The three-body force induces repulsive contributions to the monopole terms of the valence neutron-neutron interaction Ground state energies of the isotopes, which have deviations from the experimental values near drip-lines only with the microscopic two-body interaction, are found to be well reproduced up to the observed ones when the three-body interaction is included. The excitation energies of the 2{sub 1}{sup +} state in {sup 48}Ca and {sup 54}Ca are found to be enhanced with the inclusion of the three-body interaction. The three-body force thus plays a key role for the magicity of {sup 48}Ca and {sup 54}Ca. The magnetic dipole (M1) strength in {sup 48}Ca, which is fragmented in case with the microscopic two-body interaction only, is found to be concentrated and pushed up to higher excitation energy when the three-body interarction is included. An important role of the multipole components is pointed out for the concentration of the strength.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NNPDF2.1: Including heavy quark mass effects in NNPDF fits
In this contribution we present the NNPDF2.1 parton distribution functions (PDF) set. The NNPDF2.1 set is a set extracted from a global fit to Deep-Inelastic Scattering (DIS), fixed target Drell-Yan (DY), Electroweak vector boson and inclusive jet cross-sections at colliders data. It is performed using the NNPDF methodology which relies on Monte Carlo techniques for determination of uncertainties and Neural Networks as unbiased interpolants.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Exotic Interactions between Weyl Gravitons and Massless Zero-charge Spin-1/2 Particles
The consistent couplings that can be added to a 'free' theory whose Lagrangian action is written as the sum between the linearized Weyl action and that of a massless Majorana spinor are constructed by means of deforming the solution to the classical master equation.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Heavy quark spin symmetry and heavy hadronic molecules
In the heavy quark limit there is heavy quark spin symmetry. As a consequence, heavy hadrons or heavy quarkonia form spin multiplets. We argue that due to the symmetry, also heavy flavor hadronic molecules form spin multiplets, and the hyperfine splittings are the same as those between the heavy hadrons which are components of the molecules. Hence it provides a method to identify the nature of heavy hadronic molecules. As an example, we give predictions of the properties of an {eta}{sub c}{sup '}f{sub 0}(980) bound state assuming the Y(4660) to be an S-wave {psi}{sup '}f{sub 0}(980) shallow bound state. We also show that the enhancement observed in the {Lambda}{sub c}{sup +}{Lambda}{sub c}{sup -} invariant mass distribution might be the Y(4660).
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Spectrum of baryons with one charm quark
Diquark is employed to study the spectrum of baryons with one charm quark and two light quark within the mass loaded flux tube model. The spin-orbit interaction is taken into account based on the heavy quark symmetry. Some observed {Lambda}{sub c} and {Xi}{sub c} baryons are systematically classified with suggested J{sup P} quantum numbers.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Open problems in particle astrophysics
The search for an understanding of the nature of the Dark Matter is one of the fundamental problems in science. This contribution outlines the evidence for the existence of Dark Matter (DM), and discusses the possibility that it is formed by new type of Weakly Interacting Massive (m{approx} 100 GeV) elementary Particles (WIMPs). Possible methods to verify this hypothesis include the creation of these particles in high energy accelerators, the observation of the elastic scattering of ordinary nuclei with the DM particles that form the halo of the Milky Way, and the (indirect) observation of the products of the self annihilation of the DM particles in our Galaxy. Possible, controversial hints of the existence of WIMPs will be discussed.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Axino dark matter and baryon number asymmetry production by the Q-ball decay in gauge mediation
We investigate the Q-ball decay into the axino dark matter in the gauge-mediated supersymmetry breaking. In our scenario, the Q ball decays mainly into nucleons and partially into axinos to account respectively for the baryon asymmetry and the dark matter of the universe. The Q ball decays well before the big bang nucleosynthesis so that it is not affected by the decay. We show the region of the parameters which realizes this scenario.
79 ASTRONOMY AND ASTROPHYSICS↗
Cogenerating and pre-annihilating dark matter by a new gauge interaction in a unified model
Grand unified theories based on large groups (with rank ≥6) are a natural context for dark matter models. They contain Standard-Model-singlet fermions that could be dark matter candidates, and can contain new non-abelian interactions whose sphalerons convert baryons, leptons, and dark matter into each other, “cogenerating' a dark matter asymmetry comparable to the baryon asymmetry. In this paper it is shown that the same non-abelian interactions can “pre-annihilate' the symmetric component of heavy dark matter particles χ, which then decay late into light stable dark matter particles ζ that inherit their asymmetry. We derive cosmological constraints on the parameters of such models. The mass of χ must be <3000 TeV and their decays must happen when 2×10{sup −7}<T{sub dec}/m{sub χ}<10{sup −4}. It is shown that such decays can come from d=5 operators with coefficients of order 1/M{sub GUT} or 1/M{sub Pℓ}. We present a simple realization of our model based on the group SU(7).
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Model-independent Higgs coupling measurements at the LHC using the H{yields}ZZ{yields}4l lineshape
We show that combining a direct measurement of the Higgs total width from the H{yields}ZZ{yields}4l lineshape with Higgs signal rate measurements allows Higgs couplings to be extracted in a model-independent way from CERN LHC data. Using existing experimental studies with 30 fb{sup -1} at one detector of the 14 TeV LHC, we show that the couplings squared of a 190 GeV Higgs to WW, ZZ, and gg can be extracted with statistical precisions of about 10%, and a 95% confidence level upper limit on an unobserved component of the Higgs decay width of about 22% of the standard model Higgs width can be set. The method can also be applied for heavier Higgs masses.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Can the standard model C P violation near the W bags explain the cosmological baryonic asymmetry?
Not Available
Burnier, Yannis↗