Fri·Feb 10, 2017Friday·February 10, 2017

1. 01*

   Gamma-ray line constraints on Coy Dark Matter

   Andi Hektor🇪🇪 · Luca Marzola🇪🇪 · Taavi Tuvi🇪🇪

   Coy dark matter is an effective scheme in which a fermionic dark matter candidate interacts with the Standard Model fermions via a pseudoscalar mediator. This simple setup avoids the strong constraints posed by direct detection experiments in a natural way and explains, on top of the observed dark matter relic abundance, the spatially extended gamma-ray excess recently detected at the Galactic Center. In this Letter we study the phenomenology of coy dark matter accounting for a novel signature of the model: the diphoton annihilation signal induced by the Standard Model fermions at the loop level. By challenging the model with the observations of spheroidal dwarf satellite galaxies and the results of gamma-ray line searches obtained by the Fermi LAT experiment, we assess its compatibility with the measured dark matter relic abundance and the Galactic Center excesses. We show that despite the gamma-ray line constraint rules out a significant fraction of the considered parameter space, the region connected to the observed Galactic Center excess remains currently viable. Nevertheless, we find that next-generation experiments such as DAMPE, HERD and GAMMA-400 have the potential to probe exhaustively this elusive scenario.

   hep-phastro-ph.HEPRD(2017)·8 citations
2. 02*

   Atmospheric Trident Production for Probing New Physics

   Shao-Feng Ge🇩🇪 · Manfred Lindner🇩🇪 · Werner Rodejohann🇩🇪

   We propose to use atmospheric neutrinos as a powerful probe of new physics beyond the Standard Model via neutrino trident production. The final state with double muon tracks simultaneously produced from the same vertex is a distinctive signal at large Cherenkov detectors. We calculate the expected event numbers of trident production in the Standard Model. To illustrate the potential of this process to probe new physics we obtain the sensitivity on new vector/scalar bosons with coupling to muon and tau neutrinos.

   hep-phastro-ph.HEhep-exPLB(2017)·54 citations
3. 03*

   Gravitational Wave Signals of Electroweak Phase Transition Triggered by Dark Matter

   Wei Chao🇨🇳 · Huai-Ke Guo🇨🇳 · Jing Shu🇨🇳

   We study in this work a scenario that the universe undergoes a two step phase transition with the first step happened to the dark matter sector and the second step being the transition between the dark matter and the electroweak vacuums, where the barrier between the two vacuums, that is necessary for a strongly first order electroweak phase transition (EWPT) as required by the electroweak baryogenesis mechanism, arises at the tree-level. We illustrate this idea by working with the standard model (SM) augmented by a scalar singlet dark matter and an extra scalar singlet which mixes with the SM Higgs boson. We study the conditions for such pattern of phase transition to occur and especially for the strongly first order EWPT to take place, as well as its compatibility with the basic requirements of a successful dark matter, such as observed relic density and constraints of direct detections. We further explore the discovery possibility of this pattern EWPT by searching for the gravitational waves generated during this process in spaced based interferometer, by showing a representative benchmark point of the parameter space that the generated gravitational waves fall within the sensitivity of eLISA, DECIGO and BBO.

   hep-phastro-ph.HEJCAP(2017)·134 citations
4. 04*

   Explaining $B\to K^{(\ast )}{\ell }^{+}{\ell }^{-}$ anomaly by radiatively induced coupling in $U(1{)}_{\mu -\tau }$ gauge symmetry

   P. Ko🇰🇷 · Takaaki Nomura🇰🇷 · Hiroshi Okada🇹🇼

   We propose an extension of the standard model (SM) with $U(1{)}_{\mu -\tau }$ gauge symmetry, extra vectorlike quark doublets $Q_a^{\prime }$ and singlet scalar $\chi$, both of which are charged under $U(1{)}_{\mu -\tau }$ and carry {odd} dark $Z_2$ parity. Then assuming that $\chi$ is the dark matter (DM) of the universe and imposing various constraints from dark matter search, flavor physics and collider search for $Q_a^{\prime }$, one can show that radiative corrections to $b\to s{Z}^{{}^{\prime }\ast }\to s{l}^{+}{l}^{-}$ involving $Q_a^{\prime }$ and $\chi$ can induce $\Delta C_9\sim -1$ which can resolve the LHCb anomalies related with $B\to K^{(\ast )}{\ell }^{+}{\ell }^{-}$. Therefore both DM and $B$ physics anomalies could be accommodated in the model.

   hep-phPRD(2017)·73 citations
5. 05*

   Excited state mass spectra of doubly heavy $\Xi$ baryons

   Zalak Shah🇮🇳 · Ajay Kumar Rai🇮🇳

   In this paper, the mass spectra are obtained for doubly heavy $\Xi$ baryons, namely, ${\Xi }_{cc}^{+}$, ${\Xi }_{cc}^{++}$, ${\Xi }_{bb}^{-}$, ${\Xi }_{bb}^0$, ${\Xi }_{bc}^0$ and ${\Xi }_{bc}^{+}$. These baryons are consist of two heavy quarks($cc$, $bb$ and $bc$) with a light($d$ or $u$) quark. The ground, radial and orbital states are calculated in framework of Hypercentral constituent quark model with coul- omb plus linear potential. Our outcomes are also compared with other predictions, thus, the average possible range of excited states masses of these $\Xi$ baryons can be determined. The study of the Regge trajectories are performed in (n, $M^2$) and (J, $M^2$) planes and their slopes and intercepts are also determined. Lastly, the ground state magnetic moments of these doubly heavy baryons are also calculated.

   hep-phEPJC(2017)·101 citations
6. 06*

   Dark matter in the Sun: scattering off electrons vs nucleons

   Raghuveer Garani (Bonn U.)🇩🇪 · Sergio Palomares-Ruiz (Valencia U., IFIC)🇪🇸

   The annihilation of dark matter (DM) particles accumulated in the Sun could produce a flux of neutrinos, which is potentially detectable with neutrino detectors/telescopes and the DM elastic scattering cross section can be constrained. Although the process of DM capture in astrophysical objects like the Sun is commonly assumed to be due to interactions only with nucleons, there are scenarios in which tree-level DM couplings to quarks are absent, and even if loop-induced interactions with nucleons are allowed, scatterings off electrons could be the dominant capture mechanism. We consider this possibility and study in detail all the ingredients necessary to compute the neutrino production rates from DM annihilations in the Sun (capture, annihilation and evaporation rates) for velocity-independent and isotropic, velocity-dependent and isotropic and momentum-dependent scattering cross sections for DM interactions with electrons and compare them with the results obtained for the case of interactions with nucleons. Moreover, we improve the usual calculations in a number of ways and provide analytical expressions in three appendices. Interestingly, we find that the evaporation mass in the case of interactions with electrons could be below the GeV range, depending on the high-velocity tail of the DM distribution in the Sun, which would open a new mass window for searching for this type of scenarios.

   hep-phastro-ph.COJCAP(2017)·116 citations
7. 07*

   Rapidity Gaps in Double Diffraction Events at LHC and Baryon-anti Baryon Torus

   O.I. Piskounova🇷🇺

   The positive baryon-antibaryon production asymmetries that have been measured at LHC are real demonstrations of string junction dynamics in the proton-proton interactions of high energies. The topological presentation of pomeron exchange in the proton-proton collision of high energy is cylinder diagram that is covered with quark-gluon net. I assume that the process of double diffraction (DD) can be presented as a diagram of one pomeron exchange with the central loop of two pomeron cylinders, that is similar to the pomeron diagram with the handle or the pomeron torus. Taking into account that the junction of three gluons (SJ) has the positive baryon number, as well as the antijunction is of negative baryon charge, our pomeron construction can be covered by only a certain number of hexagons that are constructed of 3 string junction and 3 antijunction vertices each. It is reasonable to expect that the dynamics of rapidity gaps in DD should be determined by the number of hexagons on the surface of pomeron torus. Therefore, the gap distribution in DD events has some discrete structure in the region of large gaps. Moreover, the string-junction conglomerate could be released after DD interaction as a metastable particle. There is another multiparticle process with the pomeron loop configuration that gives an event with doubled multiplicity in the central rapidity gap. It corresponds to the cut along the pomeron loop. The events with the gap in DD as well as the events with doubled multiplicity, each go on the level of 1.2% of the inclusive production cross section.

   hep-ph2 citations
8. 08*

   Tau properties in $B\to D\tau \nu$ from visible final-state kinematics

   Rodrigo Alonso🇨🇭 · Jorge Martin Camalich🇨🇭 · Susanne Westhoff🇩🇪

   In semi-leptonic $B$ decays with a tau lepton, features of the production process are imprinted on the tau helicity states. Since the tau momentum cannot be fully reconstructed experimentally, the available information on the tau properties is encoded in its visible decay products. Focusing on the process $B\to D\tau \nu$, we find explicit relations between the tau properties and the kinematics of the charged particles in the decays $\tau \to \pi \nu$, $\tau \to \rho \nu$, and $\tau \to \ell \nu \bar{\nu }$. In particular, we show that the perpendicular polarization, $P_{\perp }$, and the forward-backward asymmetry, $A_{\tau }$, of the tau lepton can simultaneously be extracted from an angular asymmetry of the charged particle against the $D$ meson. For the most sensitive decay channel, $\tau \to \pi \nu$, we expect a relative statistical precision of about $10\%$ for $P_{\perp }$ and $A_{\tau }$ in a measurement based on $50$ab${}^{-1}$ of data at BELLE II.

   hep-phhep-exPRD(2017)·46 citations
9. 09*

   Sum-rule constraints on possible diphoton resonances at LHC

   P. Roig🇲🇽 · J.J. Sanz-Cillero🇪🇸

   The study of the forward scattering amplitude $V(k,\lambda )V(k^{\prime }{\lambda }^{\prime })\to V(k,\lambda )V(k^{\prime },{\lambda }^{\prime })$ of real massless gauge bosons $V$, e.g. photons or gluons, leads to a sum-rule that can be used to investigate beyond the Standard Model signals at LHC in the $\gamma \gamma$ channel. The sum-rule only relies on general properties such as analyticity, unitarity and crossing. We use the now buried 750 GeV diphoton resonance as a case of study to exemplify the constraints that the forward sum-rule requires to any new physics candidate. In the case of a large $\gamma \gamma$ or $gg$ partial width, of the order of 10 GeV in our 750 GeV analysis, one finds that an infinite tower of states with spin $J_R=2$ and higher must be ultimately incorporated to the beyond Standard Model theory in order to fulfill the sum-rule. We expect these techniques may be useful in next diphoton searches at LHC and future colliders.

   hep-phEPJ Web Conf.(2017)·0 citations
10. 10*

    Systematic Analysis of the Non-extensive Statistical Approach in High Energy Particle Collisions - Experiment vs. Theory

    Gábor Bíró🇭🇺 · Gergely Gábor Barnaföldi🇭🇺 · Tamás Sándor Biró🇭🇺 · Károly Ürmössy🇵🇱 · Ádám Takács🇭🇺

    The analysis of high-energy particle collisions is an excellent testbed for the non-extensive statistical approach. In these reactions we are far from the thermodynamical limit. In small colliding systems, such as electron-positron or nuclear collisions, the number of particles is several orders of magnitude smaller than the Avogadro number; therefore, finite-size and fluctuation effects strongly influence the final-state one-particle energy distributions. Due to the simple characterization, the description of the identified hadron spectra with the Boltzmann-Gibbs thermodynamical approach is insufficient. These spectra can be described very well with Tsallis-Pareto distributions instead, derived from non-extensive thermodynamics. Using the $q$-entropy formula, we interpret the microscopic physics in terms of the Tsallis $q$ and $T$ parameters. In this paper we give a view on these parameters, analyzing identified hadron spectra from recent years in a wide center-of-mass energy range. We demonstrate that the fitted Tsallis-parameters show dependency on the center-of-mass energy and particle species (mass). Our findings are described well by a QCD (Quantum Chromodynamics) inspired parton evolution ansatz. Based on this comprehensive study, apart from the evolution, both mesonic and baryonic components found to be non-extensive ($q>1$), besides the mass ordered hierarchy observed in the parameter $T$. We also study and compare in details the theory-obtained parameters for the case of PYTHIA8 Monte Carlo Generator, perturbative QCD and quark coalescence models.

    hep-phEntropy(2017)·61 citations
11. 11*

    Interactions relevant to the decoupling of the neutrini/antineutrini in the early Universe

    Evangelos Matsinos🇨🇭

    The interactions of the neutrini and antineutrini amongst themselves, as well as the interactions of these particles with the electrons and the positrons, are of interest in simulations of the early Universe and in studies of the processes involving compact stars. The objective in this paper is to create a reliable source of information regarding the differential and total cross sections of these interactions; expressions for these observables will be obtained using standard methodology. A number of relevant discrepancies in the literature will be addressed.

    hep-ph0 citations
12. 12*

    Pressure of a weakly magnetized hot and dense deconfined QCD matter in one-loop hard-thermal-loop perturbation theory

    Aritra Bandyopadhyay🇮🇳 · Bithika Karmakar🇮🇳 · Najmul Haque🇮🇳 · Munshi G. Mustafa🇮🇳

    We consider our recently obtained general structure of two point (self-energy and propagator) functions of quarks and gluons in a nontrivial background like a heat bath and an external magnetic field. Based on this, here we have computed free energy and pressure of quarks and gluons for a magnetized hot and dense deconfined QCD matter in weak field approximation. For heat bath we have used hard thermal loop perturbation theory (HTLpt) in presence of finite chemical potential. For weak field approximations we have obtained the pressure of QCD matter, both with and without the high temperature expansion. The results with high $T$ expansions are completely analytic and gauge independent but depends on the renormalization scale in addition to the temperature, chemical potential and the external magnetic field. We also discuss the modification of QCD Debye mass of such matter for an arbitrary magnetic field. Analytic expressions for Debye mass are also obtained for both strong and weak field approximation. It is found to exhibit some interesting features depending upon the three different scales, i.e, the quark mass, temperature and the strength of the magnetic field. The various divergences appearing in the quark and gluon free energies are regulated through appropriate counter terms. In weak field approximation, the low temperature behavior of the pressure is found to strongly depend on the magnetic field than that at high temperature. We also discuss the specific problem with one-loop HTLpt associated with the over-counting of certain orders in coupling.

    hep-phhep-latnucl-thPRD(2019)·73 citations
13. 13*

    Naturally Light Dirac Neutrino in Left-Right Symmetric Model

    Debasish Borah🇮🇳 · Arnab Dasgupta🇮🇳

    We study the possibility of generating tiny Dirac masses of neutrinos in Left-Right Symmetric Model (LRSM) without requiring the existence of any additional symmetries. The charged fermions acquire masses through a universal seesaw mechanism due to the presence of additional vector like fermions. The neutrinos acquire a one-loop Dirac mass from the same additional vector like charged leptons without requiring any additional discrete symmetries. The model can also be extended by an additional $Z_2$ symmetry in order to have a scotogenic version of this scenario predicting a stable dark matter candidate. We show that the latest Planck upper bound on the effective number of relativistic degrees of freedom $N_{\text{eff}}=3.15\pm 0.23$ tightly constrains the right sector gauge boson masses to be heavier than 3.548 TeV. This bound on gauge boson mass also affects the allowed values of right scalar doublet dark matter mass from the requirement of satisfying the Planck bound on dark matter relic abundance. We also discuss the possible implications of such a scenario in charged lepton flavour violation and generating observable electric dipole moment of leptons.

    hep-phJCAP(2017)·69 citations
14. 14*

    Two-Higgs-Doublet-Portal Dark-Matter Models in Light of Direct Search and LHC Data

    Chia-Feng Chang🇹🇼 · Xiao-Gang He🇨🇳 · Jusak Tandean🇹🇼

    We explore simple Higgs-portal models of dark matter (DM) with spin 1/2, 3/2, and 1, respectively, applying to them constraints from the LUX and PandaX-II direct detection experiments and from LHC measurements on the 125-GeV Higgs boson. With only one Higgs doublet, we find that the spin-1/2 DM having a purely scalar effective coupling to the doublet is viable only in a narrow range of mass near the Higgs pole, whereas the vector DM is still allowed if its mass is also close to the Higgs pole or exceeds 1.4 TeV, both in line with earlier analyses. Moreover, the spin-3/2 DM is in a roughly similar situation to the spin-1/2 DM, but has surviving parameter space which is even more restricted. We also consider the two-Higgs-doublet extension of each of the preceding models, assuming that the expanded Yukawa sector is that of the two-Higgs-doublet model of type II. We show that in these two-Higgs-doublet-portal models significant portions of the DM mass regions excluded in the simplest scenarios by direct search bounds can be reclaimed due to suppression of the effective DM interactions with nucleons at some ratios of the $CP$-even Higgs bosons' couplings to the up and down quarks. The regained parameter space contains areas which can yield a DM-nucleon scattering cross-section that is far less than its current experimental limit or even goes below the neutrino-background floor.

    hep-phastro-ph.COhep-exJHEP(2017)·29 citations
15. 15*

    Inflection-point inflation in hyper-charge oriented U(1)${}_X$ model

    Nobuchika Okada🇺🇸 · Satomi Okada🇯🇵 · Digesh Raut🇺🇸

    Inflection-point inflation is an interesting possibility to realize a successful slow-roll inflation when inflation is driven by a single scalar field with its value during inflation below the Planck mass (${\varphi }_I\lesssim M_{Pl}$). In order for a renormalization group (RG) improved effective $\lambda {\varphi }^4$ potential to develop an inflection-point, the running quartic coupling $\lambda (\varphi )$ must exhibit a minimum with an almost vanishing value in its RG evolution, namely $\lambda ({\varphi }_I)\simeq 0$ and ${\beta }_{\lambda }({\varphi }_I)\simeq 0$, where ${\beta }_{\lambda }$ is the beta-function of the quartic coupling. In this paper, we consider the inflection-point inflation in the context of the minimal gauged U(1)${}_X$ extended Standard Model (SM), which is a generalization of the minimal U(1)${}_{B-L}$ model, and is constructed as a linear combination of the SM U(1)${}_Y$ and U(1)${}_{B-L}$ gauge symmetries. We identify the U(1)${}_X$ Higgs field with the inflaton field. For a successful inflection-point inflation to be consistent with the current cosmological observations, the mass ratios among the U(1)${}_X$ gauge boson, the right-handed neutrinos and the U(1)${}_X$ Higgs boson are fixed. Focusing on the case that the extra U(1)${}_X$ gauge symmetry is mostly aligned along the SM U(1)${}_Y$ direction, we investigate a consistency between the inflationary predictions and the latest LHC Run-2 results on the search for a narrow resonance with the di-lepton final state. %In addition, the inflection-point inflation provides a unique prediction for the running of the spectral index $\alpha \simeq -2.7\times$ ($N$ is the e-folding number), which can be tested in the near future.

    hep-phastro-ph.COPRD(2017)·38 citations
16. 16*

    Dark Matter "Transporting" Mechanism Explaining Positron Excesses

    Doojin Kim🇨🇭 · Jong-Chul Park🇰🇷 · Seodong Shin🇺🇸

    We propose a novel mechanism to explain the positron excesses, which are observed by satellite-based telescopes including PAMELA and AMS-02, in dark matter (DM) scenarios. The novelty behind the proposal is that it makes direct use of DM around the Galactic Center where DM populates most densely, allowing us to avoid tensions from cosmological and astrophysical measurements. The key ingredients of this mechanism include DM annihilation into unstable states with a very long laboratory-frame life time and their "retarded" decay near the Earth to electron-positron pair(s) possibly with other (in)visible particles. We argue that this sort of explanation is not in conflict with relevant constraints from big bang nucleosynthesis and cosmic microwave background. Regarding the resultant positron spectrum, we provide a generalized source term in the associated diffusion equation, which can be readily applicable to any type of two-"stage" DM scenarios wherein production of Standard Model particles occurs at completely different places from those of DM annihilation. We then conduct a data analysis with the recent AMS-02 data to validate our proposal.

    hep-phastro-ph.HEhep-exJHEP(2018)·28 citations
17. 17*

    Disentangling Heavy Flavor at Colliders

    Philip Ilten🇺🇸 · Nicholas L. Rodd🇺🇸 · Jesse Thaler🇺🇸 · Mike Williams🇺🇸

    We propose two new analysis strategies for studying charm and beauty quarks at colliders. The first strategy is aimed at testing the kinematics of heavy-flavor quarks within an identified jet. Here, we use the SoftDrop jet-declustering algorithm to identify two subjets within a large-radius jet, using subjet flavor tagging to test the heavy-quark splitting functions of QCD. For subjets containing a $J/\psi$ or ${\rm Y}$, this declustering technique can also help probe the mechanism for quarkonium production. The second strategy is aimed at isolating heavy-flavor production from gluon splitting. Here, we introduce a new FlavorCone algorithm, which smoothly interpolates from well-separated heavy-quark jets to the gluon-splitting regime where jets overlap. Because of its excellent ability to identify charm and beauty hadrons, the LHCb detector is ideally suited to pursue these strategies, though similar measurements should also be possible at ATLAS and CMS. Together, these SoftDrop and FlavorCone studies should clarify a number of aspects of heavy-flavor physics at colliders, and provide crucial information needed to improve heavy-flavor modeling in parton-shower generators.

    hep-phhep-exPRD(2017)·43 citations
18. 18*

    Electroweak Kaluza-Klein Dark Matter

    Thomas Flacke🇰🇷 · Dong Woo Kang🇰🇷 · Kyoungchul Kong🇺🇸 · Gopolang Mohlabeng🇺🇸 · Seong Chan Park🇰🇷

    In models with universal extra dimensions (UED), the lightest Kaluza-Klein excitation of neutral electroweak gauge bosons is a stable, weakly interacting massive particle and thus is a candidate for dark matter thanks to Kaluza-Klein parity. We examine concrete model realizations of such dark matter in the context of non-minimal UED extensions. The boundary localized kinetic terms for the electroweak gauge bosons lead to a non-trivial mixing among the first Kaluza-Klein excitations of the $\mathrm{SU}(2{)}_W$ and $\mathrm{U}(1{)}_Y$ gauge bosons and the resultant low energy phenomenology is rich. We investigate implications of various experiments including low energy electroweak precision measurements, direct and indirect detection of dark matter particles and direct collider searches at the LHC. Notably, we show that the electroweak Kaluza-Klein dark matter can be as heavy as 2.4 TeV, which is significantly higher than $1.3$ TeV as is indicated as an upper bound in the minimal UED model.

    hep-phJHEP(2017)·30 citations
19. 19*

    Dark Matter Search in a Proton Beam Dump with MiniBooNE

    A.A. Aguilar-Arevalo🇲🇽 · M. Backfish🇺🇸 · A. Bashyal🇺🇸 · B. Batell🇺🇸 · B.C. Brown🇺🇸 · R. Carr🇺🇸 · A. Chatterjee🇺🇸 · R.L. Cooper🇺🇸 · P. deNiverville🇰🇷 · R. Dharmapalan🇺🇸 · Z. Djurcic🇺🇸 · R. Ford🇺🇸 and 31 other authors

    The MiniBooNE-DM collaboration searched for vector-boson mediated production of dark matter using the Fermilab 8 GeV Booster proton beam in a dedicated run with $1.86\times 10^{20}$ protons delivered to a steel beam dump. The MiniBooNE detector, 490~m downstream, is sensitive to dark matter via elastic scattering with nucleons in the detector mineral oil. Analysis methods developed for previous MiniBooNE scattering results were employed, and several constraining data sets were simultaneously analyzed to minimize systematic errors from neutrino flux and interaction rates. No excess of events over background was observed, leading to a 90\% confidence limit on the dark-matter cross section parameter, $Y={ϵ}^2{\alpha }_D(m_{\chi }/m_V{)}^4\lesssim 10^{-8}$, for ${\alpha }_D=0.5$ and for dark-matter masses of $0.01<m_{\chi }<0.3\mathrm{GeV}$ in a vector portal model of dark matter. This is the best limit from a dedicated proton beam dump search in this mass and coupling range and extends below the mass range of direct dark matter searches. These results demonstrate a novel and powerful approach to dark matter searches with beam dump experiments.

    ↳ hep-exhep-phPRL(2017)·166 citations
20. 20*

    Compton scattering off proton in the third resonance region

    Xu Cao🇨🇳 · H. Lenske🇩🇪

    Compton scattering off the proton in the third resonance region is analyzed for the first time, owing to the full combined analysis of pion- and photo-induced reactions in a coupled-channel effective Lagrangian model with K-matrix approximation. Two isospin $I=3/2$ resonances $D_{33}(1700)$ and $F_{35}(1930)$ are found to be essential in the range of 1.6 - 1.8 GeV. The recent beam asymmetry data of Compton scattering from the GRAAL facility are used to determine the helicity couplings of these resonances, and strong constraints are coming also from $\pi N$ and $K\Sigma$ photoproduction data. The possible spin and parity of new narrow resonances is discussed.

    ↳ nucl-thhep-phPLB(2017)·5 citations
21. 21*

    Double-$\beta$ Decay Matrix Elements from Lattice Quantum Chromodynamics

    Brian C. Tiburzi🇺🇸 · Michael L. Wagman🇺🇸 · Frank Winter🇺🇸 · Emmanuel Chang🇺🇸 · Zohreh Davoudi🇺🇸 · William Detmold🇺🇸 · Kostas Orginos🇺🇸 · Martin J. Savage🇺🇸 · Phiala E. Shanahan🇺🇸

    A lattice quantum chromodynamics (LQCD) calculation of the nuclear matrix element relevant to the $nn\to ppee{\overline{\nu }}_e{\overline{\nu }}_e$ transition is described in detail, expanding on the results presented in Ref. [1]. This matrix element, which involves two insertions of the weak axial current, is an important input for phenomenological determinations of double-$\beta$ decay rates of nuclei. From this exploratory study, performed using unphysical values of the quark masses, the long-distance deuteron-pole contribution to the matrix element is separated from shorter-distance hadronic contributions. This polarizability, which is only accessible in double-weak processes, cannot be constrained from single-$\beta$ decay of nuclei, and is found to be smaller than the long-distance contributions in this calculation, but non-negligible. In this work, technical aspects of the LQCD calculations, and of the relevant formalism in the pionless effective field theory, are described. Further calculations of the isotensor axial polarizability, in particular near and at the physical values of the light-quark masses, are required for precise determinations of both two-neutrino and neutrinoless double-$\beta$ decay rates in heavy nuclei.

    ↳ hep-lathep-phnucl-exnucl-thPRD(2017)·86 citations
22. 22*

    Investigating the temperature dependence of the specific shear viscosity of QCD matter with dilepton radiation

    Gojko Vujanovic🇺🇸 · Gabriel S. Denicol🇧🇷 · Matthew Luzum🇧🇷 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦

    This work reports on investigations of the effects on the evolution of viscous hydrodynamics and on the flow coefficients of thermal dileptons, originating from a temperature-dependent specific shear viscosity $\eta /s(T)$ at temperatures beyond 180 MeV formed at the Relativistic Heavy-Ion Collider (RHIC). We show that the elliptic flow of thermal dileptons can resolve the magnitude of $\eta /s$ at the high temperatures, where partonic degrees of freedom become relevant, whereas discriminating between different specific functional forms will likely not be possible at RHIC using this observable.

    ↳ nucl-thhep-phnucl-exPRC(2018)·26 citations
23. 23*

    Second-order chiral kinetic theory: Chiral magnetic and pseudomagnetic waves

    E. V. Gorbar🇺🇦 · V. A. Miransky🇨🇦 · I. A. Shovkovy🇺🇸 · P. O. Sukhachov🇨🇦

    The consistent chiral kinetic theory accurate to the second order in electromagnetic and pseudoelectromagnetic fields is derived for a relativistic matter with two Weyl fermions. By making use of such a framework, the properties of longitudinal collective excitations, which include both chiral magnetic and chiral pseudomagnetic waves, are studied. It is shown that the proper treatment of dynamical electromagnetism transforms these gapless waves into chiral (pseudo)magnetic plasmons, whose Langmuir (plasma) gap receives corrections quadratic in both magnetic and pseudomagnetic fields.

    ↳ cond-mat.mes-hallhep-phhep-thPRB(2017)·34 citations
24. 24*

    Neutrino masses from a cobimaximal neutrino mixing matrix

    Asan Damanik🇮🇩

    Recently, we have a confidence that neutrino has a tiny mass and mixing does exist among neutrino flovors as one can see from experimental data that reported by many collaborations. Based on experimental data that flavor mixing does exist in neutrino sector which imply that all three mixing angles are nonzero, we derive the neutrino mass matrix from a cobimaximal neutrino mixing matrix. We also evaluate the prediction of neutrino mass matrix with texture zero from a cobimaximal neutrino mixing matrix on neutrino masses and effective Majorana mass. By using the advantages of experimental data, the obtained neutrino masses are $m_1=0.028188$ eV, $m_2=0.029488$ eV, and $m_3=0.057676$ eV, and the effective Majorana mass is $⟨m_{\beta \beta }⟩=0.09896$ eV that can be tested in future neutrinoless double beta decay experiments

    ↳ physics.gen-phhep-ph6 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.