Mon·Oct 21, 2019Monday·October 21, 2019

1. 01*

   Improved Lower Bounds on Partial Lifetimes for Nucleon Decay Modes

   Sudhakantha Girmohanta🇺🇸 · Robert Shrock🇺🇸

   In the framework of a baryon-number-violating effective Lagrangian, we calculate improved lower bounds on partial lifetimes for proton and bound neutron decays, including $p\to {\ell }^{+}{\ell }^{\prime +}{\ell }^{\prime -}$, $n\to \bar{\nu }{\ell }^{+}{\ell }^{\prime -}$, $p\to {\ell }^{+}\nu \bar{\nu }$, and $n\to \bar{\nu }\bar{\nu }\nu$, where $\ell$ and ${\ell }^{\prime }$ denote $e$ or $\mu$, with both $\ell ={\ell }^{\prime }$ and $\ell \ne {\ell }^{\prime }$ cases. Our lower bounds are substantially stronger than the corresponding lower bounds from direct experimental searches. We also present lower bounds on $(\tau /B{)}_{p\to {\ell }^{+}\gamma }$, $(\tau /B{)}_{n\to \bar{\nu }\gamma }$, $(\tau /B{)}_{p\to {\ell }^{+}\gamma \gamma }$, and $(\tau /B{)}_{n\to \bar{\nu }\gamma \gamma }$. Our method relies on relating the rates for these decay modes to the rates for decay modes of the form $p\to {\ell }^{+}M$ and $n\to \bar{\nu }M$, where $M$ is a pseudoscalar or vector meson, and then using the experimental lower bounds on the partial lifetimes for these latter decays.

   hep-phhep-exPRD(2019)·25 citations
2. 02*

   Higgs-Photon-Photon Amplitude in the Unitary Gauge

   Er-Cheng Tsai🇹🇼

   The physical process of Higgs decaying to two photons is the most important mode in the discovery of the Higgs particle. Theoretical calculation of $H\to \gamma \gamma$ amplitude therefore provides us with an avenue to explore the underlying theory. Yet some confusion has arisen over the gauge invariant property of $H\to \gamma \gamma$ in the standard model. In this paper, we show that if dimensional regularization is adopted, the on-shell 1-loop $H\to \gamma \gamma$ amplitude calculated in the standard model is gauge invariant. In particular, we prove that the physical amplitude calculated in the unitary gauge is the same as that calculated in the Feynman gauge.

   hep-phhep-th0 citations
3. 03*

   Discriminating between $CP$ and family transformations in the bilinear space of NHDM

   Igor P. Ivanov🇵🇹 · Celso C. Nishi🇧🇷

   The scalar potential of the N-Higgs-doublet model (NHDM) is best analyzed not in the space of N complex doublets ${\varphi }_a$ but in the $N^2$-dimensional space of real-valued bilinears constructed of ${\varphi }_a^{†}{\varphi }_b$. In particular, many insights have been gained into CP violation in the 2HDM and 3HDM by studying how generalized CP transformations (GCPs) act in this bilinear space. These insights relied on the fact that GCPs, which involved an odd number of mirror reflection, could be clearly distinguished from Higgs family transformations by the sign of the determinant of the transformation matrix. It was recently pointed out that this criterion fails starting from 4HDM, where the reflection/rotation dichotomy does not exist anymore. In this paper, we restore intuition by finding a different quantity which faithfully discriminates between GCPs and Higgs family transformations in the bilinear space for any number of Higgs doublets. We also establish the necessary and sufficient conditions for an orthogonal transformation in the bilinear space to represent a viable transformation back in the space of N doublets, which is helpful if one prefers to build an NHDM directly in the bilinear space.

   hep-phPRD(2020)·1 citation
4. 04*

   Effective neutrino masses in KATRIN and future tritium beta-decay experiments

   Guo-yuan Huang🇨🇳 · Werner Rodejohann🇩🇪 · Shun Zhou🇨🇳

   Past and current direct neutrino mass experiments set limits on the so-called effective neutrino mass, which is an incoherent sum of neutrino masses and lepton mixing matrix elements. The electron energy spectrum which neglects the relativistic and nuclear recoil effects is often assumed. Alternative definitions of effective masses exist, and an exact relativistic spectrum is calculable. We quantitatively compare the validity of those different approximations as function of energy resolution and exposure in view of tritium beta decays in the KATRIN, Project 8 and PTOLEMY experiments. Furthermore, adopting the Bayesian approach, we present the posterior distributions of the effective neutrino mass by including current experimental information from neutrino oscillations, beta decay, neutrinoless double-beta decay and cosmological observations. Both linear and logarithmic priors for the smallest neutrino mass are assumed.

   hep-phhep-exPRD(2020)·25 citations
5. 05*

   Improved Upper Limits on Baryon-Number Violating Dinucleon Decays to Dileptons

   Sudhakantha Girmohanta🇺🇸 · Robert Shrock🇺🇸

   We consider effects of $n-\bar{n}$ oscillations and resultant matter instability due to dinucleons decays. We point out that existing upper bounds on the rates for the dinucleon decays $nn\to 2{\pi }^0$, $nn\to {\pi }^{+}{\pi }^{-}$, and $np\to {\pi }^{+}{\pi }^0$ imply upper bounds on the rates for dinucleon decays to dileptons $nn\to e^{+}{e}^{-}$, $nn\to {\mu }^{+}{\mu }^{-}$, $nn\to {\nu }_{\ell }{\bar{\nu }}_{\ell }$, and $np\to {\ell }^{+}{\nu }_{\ell }$, where $\ell =e,\mu ,\tau$. We present estimates for these upper bounds. Our bounds are substantially stronger than corresponding limits from direct searches.

   hep-phhep-exPLB(2020)·24 citations
6. 06*

   Phenomenology of scotogenic scalar dark matter

   Ivania M. Ávila🇨🇱 · Valentina De Romeri🇪🇸 · Laura Duarte🇧🇷 · José W. F. Valle🇪🇸

   We reexamine the minimal Singlet + Triplet Scotogenic Model, where dark matter is the mediator of neutrino mass generation. We assume it to be a scalar WIMP, whose stability follows from the same ${\mathbb{Z}}_2$ symmetry that leads to the radiative origin of neutrino masses. The scheme is the minimal one that allows for solar and atmospheric mass scales to be generated. We perform a full numerical analysis of the signatures expected at dark matter as well as collider experiments. We identify parameter regions where dark matter predictions agree with theoretical and experimental constraints, such as neutrino oscillations, Higgs data, dark matter relic abundance and direct detection searches. We also present forecasts for near future direct and indirect detection experiments. These will further probe the parameter space. Finally, we explore collider signatures associated with the mono-jet channel at the LHC, highlighting the existence of a viable light dark matter mass range.

   hep-phEPJC(2020)·72 citations
7. 07*

   CP violation and circular polarisation in neutrino radiative decay

   Shyam Balaji🇦🇺 · Maura Ramirez-Quezada🇬🇧 · Ye-Ling Zhou🇬🇧

   The radiative decay of neutral fermions has been studied for decades but $CP$ violation induced within such a paradigm has evaded attention. $CP$ violation in these processes can produce an asymmetry between circularly polarised directions of the radiated photons and produces an important source of net circular polarisation in particle and astroparticle physics observables. The results presented in this work outlines the general connection between $CP$ violation and circular polarisation for both Dirac and Majorana fermions and can be used for any class of models that produce such radiative decays. The total $CP$ violation is calculated based on a widely studied Yukawa interaction considered in both active and sterile neutrino radiative decay scenarios as well as searches for dark matter via direct detection and collider signatures. Finally, the phenomenological implications of the formalism on keV sterile neutrino decay, leptogenesis-induced right-handed neutrino radiative decay and IceCube-driven heavy dark matter decay are discussed.

   hep-phastro-ph.HEJHEP(2020)·29 citations
8. 08*

   Repurposing lattice QCD results for composite phenomenology

   Thomas DeGrand🇺🇸 · Ethan T. Neil🇺🇸

   A number of proposed extensions of the Standard Model include new strongly interacting dynamics, in the form of SU(N) gauge fields coupled to various numbers of fermions. Often, these extensions allow N = 3 as a plausible choice, or even require N = 3, such as in twin Higgs models, where the new dynamics is a "copy" of QCD. However, the fermion masses in such a sector are typically different from (often heavier than) the ones of real-world QCD, relative to the confinement scale. Many of the strong interaction masses and matrix elements for SU(3) at heavy fermion masses have already been computed on the lattice, typically as a byproduct of the approach to the physical point of real QCD. We provide a summary of these relevant results for the phenomenological community.

   hep-phhep-latPRD(2020)·38 citations
9. 09*

   Baryon preclustering at the freeze-out of heavy-ion collisions and light-nuclei production

   Edward Shuryak🇺🇸 · Juan M. Torres-Rincon🇩🇪

   Following the idea of nucleon clustering and light-nuclei production in relativistic heavy-ion collisions close to the QCD critical-end point, we address the quantum effects affecting the interaction of several nucleons at finite temperature. For this aim we use the $K$-harmonics method to four-nucleon states ($\alpha$ particle), and also develop a novel semiclassical "flucton" method at finite temperature, based on certain classical paths in Euclidean time, and apply it to two- and four-particle configurations. To study possible effects on the light-nuclei production close to the QCD critical point, we also made such calculations with modified internuclear potentials. For heavy-ion experiments, we propose new measurements of light-nuclei multiplicity ratios which may show enhancements due to baryon preclustering. We point out the special role of the $\mathcal{O}(50)$ four-nucleon excitations of $\alpha$-particle, feeding into the final multiplicities of $d,t$, ${}^3$He and ${}^4$He, and propose to directly look for their two-body decays.

   ↳ nucl-thhep-phPRC(2020)·53 citations
10. 10*

    Electroweak properties of kaons in a nuclear medium

    Parada T. P. Hutauruk🇰🇷 · K. Tsushima🇧🇷

    Kaon electroweak properties in symmetric nuclear matter are studied in the Nambu--Jona-Lasinio model using the proper-time regularization. The valence quark properties in symmetric nuclear matter are calculated in the quark-meson coupling model, and they are used as inputs for studying the in-medium kaon properties in the NJL model. We evaluate the kaon decay constant, kaon-quark coupling constant, and $K^{+}$ electromagnetic form factor by two different approaches. Namely, by two different ways of calculating the in-medium constituent quark masses of the light quarks. We predict that, in both approaches, the kaon decay constant and kaon-quark coupling constant decrease as nuclear density increases, while the $K^{+}$ charge radius increases by 20-25\% at normal nuclear density.

    ↳ nucl-thhep-phnucl-ex12 citations
11. 11*

    Constraints on the String T-Duality Propagator from the Hydrogen Atom

    Michael F. Wondrak🇩🇪 · Marcus Bleicher🇩🇪

    We investigate the implications of a string-theory modified propagator in the high-precision regime of quantum mechanics. In particular, we examine the situation in which string theory is compactified at the T-duality self-dual radius. The corresponding propagator is closely related to the one derived from the path integral duality. Our focus is on the hydrogen ground state energy and the $1{\text{S}}_{1/2}-2{\text{S}}_{1/2}$ transition frequency as they are the most precisely explored properties of the hydrogen atom. In our analysis, the T-duality propagator affects the photon field leading to a modified Coulomb potential. Thus, our study is complementary to investigations where the electron evolution is modified as in studies of a minimal length in the context of the generalized uncertainty principle. The first manifestation of the T-duality propagator arises at fourth order in the fine-structure constant, including a logarithmic term. The constraints on the underlying parameter, the zero-point length, reach down to $3.9\times 10^{-19}\text{m}$ and are in full agreement with previous studies on black holes.

    ↳ gr-qchep-phhep-thquant-phSymmetry(2019)·7 citations
12. 12*

    Mass Production of Type IIA dS Vacua

    Renata Kallosh🇺🇸 · Andrei Linde🇺🇸

    A three-step procedure is proposed in type IIA string theory to stabilize multiple moduli in a dS vacuum. The first step is to construct a progenitor model with a localized stable supersymmetric Minkowski vacuum, or a discrete set of such vacua. It can be done, for example, using two non-perturbative exponents in the superpotential for each modulus, as in the KL model. A large set of supersymmetric Minkowski vacua with strongly stabilized moduli is protected by a theorem on stability of these vacua in absence of flat directions. The second step involves a parametrically small downshift to a supersymmetric AdS vacuum, which can be achieved by a small change of the superpotential. The third step is an uplift to a dS vacuum with a positive cosmological constant using the $\overline{D6}$-brane contribution. Stability of the resulting dS vacuum is inherited from the stability of the original supersymmetric Minkowski vacuum if the supersymmetry breaking in dS vacuum is parametrically small.

    ↳ hep-thgr-qchep-phmath-ph+1JHEP(2020)·17 citations
13. 13*

    Probe the tilted Quark-Gluon Plasma with charmonium directed flow

    Baoyi Chen🇨🇳 · Maoxin Hu · Huanyu Zhang🇨🇳 · Jiaxing Zhao🇨🇳

    Charmonium directed flows are studied based on transport model coupled with the realistic three dimensional expansions of the bulk medium. The non-central symmetric nucleus-nucleus collisions can generate the rotating quark-gluon plasma (QGP) with symmetry-breaking longitudinal distributions. In $\sqrt{s_{NN}}=200$ GeV Au-Au semi-central collisions, charmonium are primordially produced in the initial hard process, they are mainly dissociated by the initial tilted source with high temperatures and then move out of the bulk medium to keep the early information of the medium. Charmonia are less affected by the hydrodynamic expansions of QGP where its tilted shape is being diluted. This biased dissociation can generate directed flows of $J/\psi$ and $\psi (2S)$ which are much larger than the values of light charged hadrons and open heavy flavor. They are sensitive and clean to the effect of QGP rapidity-odd initial energy densities.

    ↳ nucl-thhep-phPLB(2020)·27 citations
14. 14*

    HALL POST INEQUALITIES: review and application to molecules and tetraquarks

    Jean-Marc Richard🇫🇷 · Alfredo Valcarce🇪🇸 · Javier Vijande🇪🇸

    A review is presented of the Hall-Post inequalities that give lower-bounds to the ground-state energy of quantum systems in terms of energies of smaller systems. New applications are given for systems experiencing both a static source and inner interactions, as well as for hydrogen-like molecules and for tetraquarks in some quark models. In the latter case, the Hall-Post inequalities constrain the possibility of deeply-bound exotic mesons below the threshold for dissociation into two quark-antiquark mesons. We also emphasize the usefulness of the Hall-Post bounds in terms of 3-body energies when some 2-body subsystems are ill defined or do not support any bound state.

    ↳ nucl-thcond-mat.quant-gashep-phphysics.atm-clusAnnals Phys.(2020)·23 citations
15. 15*

    Evaluation of pion-nucleon sigma term in Dyson-Schwinger equation approach of QCD

    Jing-Hui Huang🇨🇳 · Ting-Ting Sun🇨🇳 · Huan Chen🇨🇳

    We calculate the variation of the chiral condensate in medium with respect to the quark chemical potential and evaluate the pion-nucleon sigma term via the Hellmann-Feynman theorem. The variation of chiral condensate in medium are obtained by solving the truncated Dyson-Schwinger equation for quark propagator at finite chemical potential, with different models for the quark-gluon vertex and gluon propagator. We obtain the value of the sigma term ${\sigma }_{\pi N}$ = 62(1)(2) MeV, where the first represents the systematic error due to our different model for the quark-gluon vertex and gluon propagator and the second represents a statistical error in our linear fitting procedure.

    ↳ nucl-thhep-phPRD(2020)·15 citations
16. 16*

    $Insight$-HXMT study of the timing properties of Sco X-1

    S.M. Jia · Q.C. Bu · J.L. Qu · F.J. Lu · S.N. Zhang · Y. Huang · X. Ma · L. Tao · G. C. Xiao · W. Zhang · L. Chen · L.M. Song and 98 other authors

    We present a detailed timing study of the brightest persistent X-ray source Sco X-1 using the data collected by the Hard X-ray Modulation Telescope ($Insight$-HXMT) from July 2017 to August 2018. A complete $Z$-track hardness-intensity diagram (HID) is obtained. The normal branch oscillations (NBOs) at $\sim$ 6 Hz in the lower part of the normal branch (NB) and the flare branch oscillations (FBOs) at $\sim$ 16 Hz in the beginning part of the flaring branch (FB) are found in observations with the Low Energy X-ray Telescope (LE) and the Medium Energy X-ray Telescope (ME) of $Insight$-HXMT, while the horizontal branch oscillations (HBOs) at $\sim$ 40 Hz and the kilohertz quasi-periodic oscillations (kHz QPOs) at $\sim$ 800 Hz are found simultaneously up to 60 keV for the first time on the horizontal branch (HB) by the High Energy X-ray Telescope (HE) and ME. We find that for all types of the observed QPOs, the centroid frequencies are independent of energy, while the root mean square (rms) increases with energy; the centroid frequencies of both the HBOs and kHz QPOs increase along the $Z$-track from the top to the bottom of the HB; and the NBOs show soft phase lags increasing with energy. A continuous QPO transition from the FB to NB in $\sim$ 200 s are also detected. Our results indicate that the non-thermal emission is the origin of all types of QPOs, the innermost region of the accretion disk is non-thermal in nature, and the corona is nonhomogeneous geometrically.

    ↳ astro-ph.HEhep-phJHEAp(2020)·5 citations
17. 17*

    Lattice study of electromagnetic conductivity of quark-gluon plasma in external magnetic field

    Nikita Yu. Astrakhantsev🇨🇭 · Victor V. Braguta🇷🇺 · Massimo D'Elia🇮🇹 · Andrey Yu.Kotov🇷🇺 · Aleksandr A. Nikolaev🇬🇧 · Francesco Sanfilippo🇮🇹

    We study the electromagnetic (e.m.) conductivity of QGP in a magnetic background by lattice simulations with $N_f=2+1$ dynamical rooted staggered fermions at the physical point. We study the correlation functions of the e.m.~currents at $T=200,250$\,MeV and use the Tikhonov approach to extract the conductivity. This is found to rise with the magnetic field in the direction parallel to it and to decrease in the transverse direction, giving evidence for both the Chiral Magnetic Effect and the magnetoresistance phenomenon in QGP. We also estimate the chiral charge relaxation time in QGP.

    ↳ hep-lathep-phhep-thPRD(2020)·99 citations
18. 18*

    Secular effects of Ultralight Dark Matter on Binary Pulsars

    Diego Blas🇬🇧 · Diana López Nacir🇦🇷 · Sergey Sibiryakov🇨🇭

    Dark matter (DM) can consist of very light bosons behaving as a classical scalar field that experiences coherent oscillations. The presence of this DM field would perturb the dynamics of celestial bodies, either because the (oscillating) DM stress tensor modifies the gravitational potentials of the galaxy, or if DM is directly coupled to the constituents of the body. We study secular variations of the orbital parameters of binary systems induced by such perturbations. Two classes of effects are identified. Effects of the first class appear if the frequency of DM oscillations is in resonance with the orbital motion; these exist for general DM couplings including the case of purely gravitational interaction. Effects of the second class arise if DM is coupled quadratically to the masses of the binary system members and do not require any resonant condition. The exquisite precision of binary pulsar timing can be used to constrain these effects. Current observations are not sensitive to oscillations in the galactic gravitational field, though a discovery of pulsars in regions of high DM density may improve the situation. For DM with direct coupling to ordinary matter, the current timing data are already competitive with other existing constraints in the range of DM masses $\sim 10^{-22}-10^{-18}\mathrm{eV}$. Future observations are expected to increase the sensitivity and probe new regions of parameters.

    ↳ gr-qcastro-ph.HEhep-phPRD(2020)·61 citations
19. 19*

    Theoretical study of deeply virtual Compton scattering off ${}^4$He

    Sara Fucini🇮🇹 · Sergio Scopetta🇮🇹 · Michele Viviani🇮🇹

    An interesting breakthrough in understanding the elusive inner content of nuclear systems in terms of partonic degrees of freedom is represented by deeply virtual Compton scattering processes. In such a way, tomographic view of nuclei and bound nucleons in coordinate space could be achieved for the first time. Moreover, nowadays experimental results for such a process considering ${}^4$He targets recently released at Jefferson Lab are available. In this talk, the recent results of our rigorous Impulse Approximation for DVCS off ${}^4$He, in terms of state-of-the-art models of the nuclear spectral function and of the parton structure of the bound proton, able to explain present data, has been shown.

    ↳ nucl-thhep-phSciPost Phys.Proc.(2020)·0 citations
20. 20*

    Breaking a dark degeneracy: The gamma-ray signature of early matter domination

    M. Sten Delos🇺🇸 · Tim Linden🇺🇸 · Adrienne L. Erickcek🇺🇸

    The Universe's early thermal history is poorly constrained, and it is possible that it underwent a period of early matter domination driven by a heavy particle or an oscillating scalar field that decayed into radiation before the onset of Big Bang nucleosynthesis. The entropy sourced by this particle's decay reduces the cross section required for thermal-relic dark matter to achieve the observed abundance. This degeneracy between dark matter properties and the thermal history vastly widens the field of viable dark matter candidates, undermining efforts to constrain dark matter's identity. Fortunately, an early matter-dominated era also amplifies density fluctuations at small scales and leads to early microhalo formation, boosting the dark matter annihilation rate and bringing smaller cross sections into the view of existing indirect-detection probes. Employing several recently developed models of microhalo formation and evolution, we develop a procedure to derive indirect-detection constraints on dark matter annihilation in cosmologies with early matter domination. This procedure properly accounts for the unique morphology of microhalo-dominated signals. While constraints depend on dark matter's free-streaming scale, the microhalos make it possible to obtain upper bounds as small as $⟨\sigma v⟩\lesssim 10^{-32}$ cm${}^3$s${}^{-1}$ using Fermi-LAT observations of the isotropic gamma-ray background and the Draco dwarf galaxy.

    ↳ astro-ph.COastro-ph.HEhep-phPRD(2019)·57 citations
21. 21*

    $Insight$-HXMT Science Operations

    S.M. Jia · X. Ma🇨🇳 · Y. Huang🇨🇳 · W.Z. Zhang🇨🇳 · G. Ou🇨🇳 · L.M. Song🇨🇳 · J.L. Qu🇨🇳 · S. Zhang🇨🇳 · L. Chen🇨🇳

    The Hard X-ray Modulation Telescope ($Insight$-HXMT) was successfully launched on June 15th, 2017. It performs broad band X-ray scan survey of the Galactic Plane to detect new black holes and other objects in active states. It also observes X-ray binaries to study their X-ray variabilities. Here we will introduce the Science Operations of $Insight$-HXMT, which is responsible for collecting and evaluating observation proposals, scheduling observations, and monitoring the working status of the payloads.

    ↳ astro-ph.IMhep-ph1 citation
22. 22*

    Flowing with the Temporal Renormalisation Group

    Lukas Corell🇩🇪 · Anton K. Cyrol🇩🇪 · Markus Heller🇩🇪 · Jan M. Pawlowski🇩🇪

    We discuss the far-from-equilibrium evolution of ${\varphi }^3$-theory in $1+1$ dimensions with the temporal functional renormalisation group \cite{Gasenzer:2007za, Gasenzer:2010rq}. In particular, we show that this manifestly causal approach leads to novel one-loop exact equations for fully dressed correlation functions. Within this setup, we numerically compute the dynamical propagator. Its behaviour suggests self-similarity far from equilibrium in a restricted momentum regime. We discuss the scaling exponents for our solution, as well as the numerical satisfaction of energy and particle number conservation. We also derive a simple exact representation of the expectation value of the energy-momentum tensor solely in terms of the propagator.

    ↳ hep-thcond-mat.othercond-mat.stat-mechhep-phPRD(2021)·32 citations
23. 23*

    Top Quark Mixed Hybrid Meson and the Quark-Gluon Plasma

    Leonard S. Kisslinger🇺🇸 · Debasish Das🇮🇳

    Using the method of QCD Sum Rules we estimate the energy of lowest energy top quark meson state with a hybrid admixture. This new estimate uses the previous estimates of hybrid charmonium and upsilon states, but with the mass of the top quark mass being much greater than the charm and bottom quark masses. We discuss production of mixed hybrid top quark mesons and possible detection of the creation of the Quark-Gluon Plasma via Relativistic Heavy Ion Collisions.

    ↳ physics.gen-phhep-phMod.Phys.Lett.A(2019)·2 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.