Wed·Dec 25, 2019Wednesday·December 25, 2019

1. 01*

   Composite dark matter phenomenology in the presence of lighter degrees of freedom

   Maria Ramos🇵🇹

   Scalar singlet dark matter in anomaly-free composite Higgs models is accompanied by exotic particles to which the dark matter annihilates. The latter can therefore freeze out even in the absence of couplings to the Standard Model. In this regime, both current and future direct detection constraints can be avoided. Moreover, due to the different decay modes of the extra particles, the dark matter candidate can even escape indirect detection constraints. Assessing this issue requires dedicated simulations of the gamma ray spectrum, that we provide in the present article in the context of $SO(7)/SO(6)$. For the parameter space region that evades constraints from dark matter experiments, we develop new analyses to be performed at a future 100 TeV collider based on the search of the new particles produced in the decay of heavy vector-like quarks.

   hep-phJHEP(2020)·29 citations
2. 02*

   Exact Relations for Twist-3 Gluon Distribution and Fragmentation Functions from Operator Identities

   Yuji Koike🇯🇵 · Kenta Yabe🇯🇵 · Shinsuke Yoshida🇨🇳

   We perform a systematic study on the twist-3 gluon distribution and fragmentation functions which appear in the collinear twist-3 factorization for hard inclusive processes. Three types of twist-3 distribution and fragmentation functions, i.e., intrinsic, kinematical and dynamical ones, which are necessary to describe all kinds of twist-3 cross sections, are related to each other by the operator identities based on the QCD equation of motion and the Lorentz invariance properties of the correlation functions. We derive the exact relations for all twist-3 gluonic distribution and fragmentation functions for a spin-1/2 hadron. Those relations allow one to express intrinsic and kinematical twist-3 gluon functions in terms of the twist-2 and dynamical twist-3 functions, which provides a basis for the renormalization of intrinsic and kinematical twist-3 functions. In addition, those model independent relations are crucial to guarantee gauge invariance and frame independence properties of the twist-3 cross sections.

   hep-phPRD(2020)·28 citations
3. 03*

   Reanalysis of the most strange dibaryon within constituent quark models

   Hongxia Huang🇨🇳 · Xinmei Zhu🇨🇳 · Jialun Ping🇨🇳

   The most strange dibaryon $\Omega \Omega$ with quantum numbers $S=-6$, $I=0$, and $J^P=0^{+},1^{-},2^{+},3^{-}$ is reanalyzed in the framework of quark delocalization color screening model (QDCSM) and chiral quark model (ChQM). The $\Omega \Omega$ dibaryon with $J^P=0^{+}$ is bound, and the one with other quantum numbers $J^P=1^{-},2^{+},3^{-}$ are all unbound in our calculation. The low-energy scattering phase shifts, the scattering length, and the effective range of the $\Omega \Omega$ dibaryon with $J^P=0^{+}$ also support the existence of such strange dibaryon. This dibaryon is showed to be a shallow bound state in QDCSM, while the binding energy becomes much larger in the ChQM by including the effect of the hidden-color channel coupling. And the scalar nonet meson-exchange in the ChQM also provides more attraction for the $\Omega \Omega$ system. Experimental search for such most strange dibaryon will provide much information for understanding the hadron-hadron interactions in different quark models.

   hep-phnucl-thPRC(2020)·10 citations
4. 04*

   Diffractive Dissociation of Alpha Particles as a Test of Isophobic Short-Range Correlations inside Nuclei

   Jennifer Rittenhouse West🇺🇸 · Stanley J. Brodsky🇺🇸 · Guy F. de Téramond🇨🇷 · Iván Schmidt🇨🇱

   The CLAS collaboration at Jefferson Laboratory has compared nuclear parton distributions for a range of nuclear targets and found that the EMC effect measured in deep inelastic lepton-nucleus scattering has a strongly "isophobic" nature. This surprising observation suggests short-range correlations between neighboring $n$ and $p$ nucleons in nuclear wavefunctions that are much stronger compared to $p-p$ or $n-n$ correlations. In this paper we propose a definitive experimental test of the nucleon-nucleon explanation of the isophobic nature of the EMC effect: the diffractive dissociation on a nuclear target $A$ of high energy ${}^4\mathrm{He}$ nuclei to pairs of nucleons $n$ and $p$ with high relative transverse momentum, $\alpha +A\to n+p+A^{\prime }+X$. The comparison of $n-p$ events with $p-p$ and $n-n$ events directly tests the postulated breaking of isospin symmetry. The experiment also tests alternative QCD-level explanations for the isophobic EMC effect. In particular it will test a proposal for hidden-color degrees of freedom in nuclear wavefunctions based on isospin-zero $[ud]$ diquarks.

   hep-phnucl-exnucl-thPLB(2020)·8 citations
5. 05*

   Unraveling the unintegrated gluon distribution in the proton via $\rho$-meson leptoproduction

   Francesco Giovanni Celiberto🇮🇹

   Sufficiently inclusive processes, like the deep inelastic scattering (DIS), are described in terms of scale-dependent parton distributions, which correspond to the density of partons with a given longitudinal momentum fraction, integrated over the parton transverse momentum. For less inclusive processes, one needs to consider densities unintegrated over the transverse momentum. This work focuses on the unintegrated gluon distribution (UGD), describing the probability that a gluon can be emitted by a colliding proton, with definite longitudinal fraction and transverse momentum. Through the leptoproduction of the $\rho$-meson at HERA, existent models for the UGD will be investigated and compared with experimental data.

   hep-phNuovo Cim.C(2019)·94 citations
6. 06*

   Optimizing the Mellin-Barnes Approach to Numerical Multiloop Calculations

   Ievgen Dubovyk🇵🇱 · Janusz Gluza🇵🇱 · Tord Riemann🇵🇱

   The status of numerical evaluations of Mellin-Barnes integrals is discussed, in particular, the application of the quasi-Monte Carlo integration package QMC to the efficient calculation of multi-dimensional integrals.

   hep-phActa Phys.Polon.B(2019)·9 citations
7. 07*

   Simple Theory of Chiral Fermion Dark Matter

   Tomohiro Abe🇯🇵 · K. S. Babu🇺🇸

   We propose a theory of chiral fermion dark matter (DM) with an isospin-3/2 fermion of a dark sector $SU(2{)}_D$ gauge symmetry, which is arguably the simplest chiral theory. An isospin-3 scalar breaks $SU(2{)}_D$ down to a discrete non-Abelian group $T^{\prime }$ and generates the DM mass. The $SU(2{)}_D$ gauge symmetry protects the DM mass and guarantees its stability. We derive consistency conditions for the theory and study its DM phenomenology. In some regions of parameters of the theory a two-component DM scenario is realized, consisting of a fermion and a boson, with the boson being the lightest $T^{\prime }$ nonsinglet field. In the case of single component fermionic DM, we find that internal consistency of the theory, perturbativity arguments, and the observed relic abundance limit the DM mass to be less than $280$ GeV, except when $s$-channel resonance regions are open for annihilation. For a significant part of the parameter space, the theory can be tested in DM direct detection signals at the LZ and XENONnT experiments.

   hep-phPRD(2021)·8 citations
8. 08*

   TAUOLA update for decay channels with $e^{+}{e}^{-}$ pairs in the final state

   S. Antropov (1)🇵🇱 · Sw. Banerjee (2)🇺🇸 · Z. Was (1)🇵🇱 · J. Zaremba (1) ((1) Institute of Nuclear Physics Polish Academy of Sciences, PL-31342 Krakow, Poland, (2) University of Louisville, Louisville, KY 40292, USA)🇵🇱

   With the arrival of high luminosity B-factories like the Belle II experiment, $\tau$ decay measurements have become more precise than ever, allowing rarer processes to be explored, and finer details of $\tau$ decays to be studied. These are important to understand the spectrum of intermediate particles produced in $\tau$ decays. Therefore Monte Carlo generators, like the TAUOLA program, have to facilitate precision analysis as well as confront new models that constantly emerge with the availability of high statistics experimental data. New decay channels and models may lead to large variation of matrix elements size within the available phase space, as in the case when $e^{+}{e}^{-}$ pairs are present in final state. It requires appropriate presampler of the phase space generator and a proper documentation to help users introduce their own models. While releasing a new update, it is important for the TAUOLA Monte Carlo library to maintain the general structure of the previous versions to preserve backward compatibility. The aim is to minimize changes from the user perspective. This paper presents a demonstration of new models implementation facilitated by the current update.

   hep-phComput.Phys.Commun.(2023)·10 citations
9. 09*

   Parametrics of electromagnetic searches for axion dark matter

   Robert Lasenby🇺🇸

   Light axion-like particles occur in many theories of beyond-Standard-Model physics, and may make up some or all of the universe's dark matter. One of the ways they can couple to the Standard Model is through the electromagnetic $F_{\mu \nu }{\tilde{F}}^{\mu \nu }$ portal, and there is a broad experimental program, covering many decades in mass range, aiming to search for axion dark matter via this coupling. In this paper, we derive limits on the absorbed power, and coupling sensitivity, for a broad class of such searches. We find that standard techniques, such as resonant cavities and dielectric haloscopes, can achieve O(1)-optimal axion-mass-averaged signal powers, for given volume and magnetic field. For low-mass (frequency $\ll$ GHz) axions, experiments using static background magnetic fields generally have suppressed sensitivity - we discuss the physics of this limitation, and propose experimental methods to avoid it, such as microwave up-conversion experiments. We also comment on the detection of other forms of dark matter, including dark photons, as well as the detection of relativistic hidden sector particles.

   hep-phhep-exPRD(2021)·31 citations
10. 10*

    Probing Dark Matter Axions using the Hyperfine Structure Splitting of Hydrogen Atoms

    Qiaoli Yang🇨🇳 · Shiqin Dong🇨🇳

    QCD axions can be a substantial part of dark matter if their mass $m_a\sim 10^{-5}$eV. Since the axions were created by the misalignment mechanism, their local energy spectrum density is large. Consequently, the axion-induced atomic transition rate is enhanced if the atomic energy gap matches the axion mass. The hyperfine splitting between the spin 0 singlet ground state and the spin 1 triplet state of hydrogen is $0.59\times 10^{-5}$eV, which is close to the preferred mass of dark matter axions. With an energy gap adjustment by applying a weak Zeeman magnetic field, dark matter axions can induce atomic hydrogen transitions. Furthermore, because the total spins of the hydrogen triplet and singlet differ, the axion-induced transitions are detectable by a Stern--Gerlach apparatus or a sensitive magnetic field detector. A potential realization of the proposed scheme can be similar to existing hydrogen masers.

    hep-phhep-exphysics.atm-clusPLB(2023)·18 citations
11. 11*

    QCD vacuum replicas are metastable

    P. Bicudo🇵🇹 · J.E. Ribeiro🇵🇹

    A metastable phase has important physical implications, since it may form vacuum bubbles detectable experimentally, whereas an unstable vacuum instantly explodes. It is well known, due to chiral symmetry breaking, there are at least two very different QCD vacua. At T=0 and in the true vacuum, the scalar and pseudoscalar, or the vector and axial vector are not degenerate, and in the chiral limit, the pseudoscalar ground states are Goldstone bosons. At T=0 the chiral invariant vacuum is an unstable vacuum, decaying through an infinite number of scalar and pseudoscalar tachyons. Moreover QCD vacuum replicas, an infinite tower of excited vacuum solutions, which energy density lies between the true vacuum and the chiral invariant vacuum, have been predicted in the Coulomb gauge, due to the non-linearity of the mass gap equation with a confining interaction. It remained to show whether the QCD replicas are metastable or unstable. In this paper the spectrum of quark-antiquark systems, is studied in the true vacuum and in the first excited QCD replicas. The mass gap equation for the vacua and the Salpeter-RPA equation for the mesons are solved for a simple chiral invariant and confining quark model approximating QCD in the Coulomb gauge. We find no tachyons, thus showing the QCD replicas in our approach is indeed metastable. Moreover the energy spectra of the mesonic quark-antiquark systems in the first replicas are close to the one of the true vacuum.

    hep-phPLB(2020)·3 citations
12. 12*

    Spatio-temporal linear instability analysis for arbitrary dispersion relations on the Lefschetz thimble in multidimensional spacetime

    Taiki Morinaga🇯🇵 · Shoichi Yamada🇯🇵

    In linear stability analysis of field quantities described by partial differential equations, the well-established classical theory is all but impossible to apply to concrete problems in its entirety even for uniform backgrounds when the spatial dimension is more than 1. In this study, using the Lefschetz thimble method, we develop a new formalism to give an explicit expression to the asymptotic behavior of linear perturbations. It is not only more mathematically rigorous than the previous theory but also useful practically in its applications to realistic problems, and, as such, has an impact on broad subjects in physics.

    ↳ math-phastro-ph.HEhep-phmath.MP+21 citation
13. 13*

    Magneto-vortical effect in strongly coupled plasma

    Yanyan Bu🇨🇳 · Shu Lin🇨🇳

    Based on a holographic model incorporating both chiral anomaly and gravitational anomaly, we study the effect of magneto-vortical coupling on transport properties of a strongly coupled plasma. The focus of present work is on the generation of a vector charge density and an axial current, as response to vorticity in a magnetized plasma. The transport coefficients parameterising the vector charge density and axial current are calculated both analytically (in the weak magnetic field limit) and also numerically (for general values of the magnetic field). We find the generation of vector charge receives both non-anomalous and anomalous contributions, with the non-anomalous contribution dominating in the limit of strong magnetic field and the anomalous contribution sensitive to both chiral anomaly and gravitational anomaly. On the contrary, we find the axial current is induced entirely due to the gravitational anomaly, thus we interpret the axial current generation as chiral vortical effect. The corresponding chiral vortical conductivity is found to be suppressed by the magnetic field. By Onsager relation, these transport coefficients are responsible for the generation of a thermal current due to a transverse electric field or a transverse axial magnetic field, which we call thermal Hall effect and thermal axial magnetic effect, respectively.

    ↳ hep-thhep-phnucl-thEPJC(2020)·10 citations
14. 14*

    SO(9) characterisation of the Standard Model gauge group

    Kirill Krasnov🇬🇧

    A recent series of works by M. Dubois-Violette, I. Todorov and S. Drenska characterised the SM gauge group GSM as the subgroup of SO(9) that, in the octonionic model of the later, preserves the split O=C+C3 of the space of octonions into a copy of the complex plane plus the rest. This description, however, proceeded via the exceptional Jordan algebras J3(O), J2(O) and and this sense remained indirect. One of the goals of this paper is to provide as explicit description as possible and also clarify the underlying geometry. The other goal is to emphasise the role played by different complex structures in the spaces O and O2. We provide a new characterisation of GSM: The group GSM is the subgroup of Spin(9) that commutes with of a certain complex structure J in the space O2 of Spin(9) spinors. The complex structure J is parametrised by a choice of a unit imaginary octonion. This characterisation of GSM is essentially octonionic in the sense that J is restrictive because octonions are non-associative. The quaternionic analog of J is the complex structure in the space H2 of Spin(5) spinors that commutes with all Spin(5) transformations.

    ↳ hep-thhep-phJ.Math.Phys.(2021)·19 citations
15. 15*

    Hidden Analytic Structure of Higgs Amplitudes and Maximal Transcendentality Principle

    Qingjun Jin🇨🇳 · Gang Yang🇨🇳

    We present the computation of two-loop Higgs plus three-parton amplitudes with dimension-seven operators in Higgs effective field theory. The computation is based on the combination of unitarity cut and integration by parts methods in an unconventional way. The analytic results take remarkably simple form. In particular, the results show that the QCD and N=4 SYM results share the same leading transcendental parts. This generalizes the so-call maximal transcendentality principle to the Higgs amplitudes with high dimension operators and also with fundamental external quark states. Further simplicity also exists in lower transcendental parts, suggesting hidden structures beyond maximal transcendentality.

    ↳ hep-thhep-phPoS(2019)·0 citations
16. 16*

    Quartet-metric gravity, scalar-graviton dark substance and vacuum energy screening: extending GR vs. its WTDiff alternative

    Yury F. Pirogov🇷🇺

    In the frameworks of the effective field theory of metric supplemented by some distinct dynamical coordinates parametrized, in turn, by a scalar quartet -- the so-called quartet-metric gravity -- the extension of tensor gravity through a massive scalar graviton in addition to the massless tensor one is consistently exposed. The field equations for the two realizations of such an extension originating from the classically equivalent prototype theories - General Relativity (GR) and its Weyl transverse (WTDiff) alternative - are derived and argued to be, generally, non-equivalent, with the pure-gravity case manifesting this explicitly in detail. A splitting of the cosmological constant onto the gravitating and non-gravitating parts, with a partial screening of the vacuum energy through an emergent scalar-graviton dark substance, is considered. A prior importance of treating the WTDiff gravity as a prototype one on par with GR, when looking for a putative next-to-GR extended theory of gravity with a scalar-graviton dark substance, is stressed.

    ↳ gr-qchep-ph1 citation
17. 17*

    Dark matter with excitable levels

    Andrew J. Wren🇬🇧

    This paper explores the possibility that dark matter particles are objects with a set of excitable levels, as for a string or drum. A change in excitation is associated with the absorption or emission of a photon, and the probability of such a change is dependent on the ambient photon energy density. Particle mass comes entirely from excitations. Such dark matter with excitable levels, or DMWEL, particles have a distribution of masses which freezes out to its present-day form during the early universe. In the particular model considered, consistency with Planck CMB anisotropy observations implies a cautious lower bound on the energy of the first excitable level of 2 to 200 eV for a set of reference parameters. While laboratory detection looks to require a considerable increase in the power of controlled light-sources, it might be possible in the near future to detect or constrain DMWEL further through improved anisotropy observations, closer determination of the CMB's maximum deviation from a blackbody shape, or from gravitational probes of the dark matter power spectrum. For certain parameters near to the boundary of the region allowed by CMB anisotropies, DMWEL dark matter is cold, but with a cut-off halo mass many orders of magnitude greater than that typical for WIMP cold dark matter.

    ↳ astro-ph.COhep-ph0 citations
18. 18*

    Time of Flight and Supernova Progenitor Effects on the Neutrino Halo

    John F. Cherry🇺🇸 · George M. Fuller🇺🇸 · Shunsaku Horiuchi🇺🇸 · Kei Kotake🇯🇵 · Tomoya Takiwaki🇯🇵 · Tobias Fischer🇵🇱

    We argue that the neutrino halo, a population of neutrinos that have undergone direction-changing scattering in the stellar envelope of a core-collapse supernova (CCSNe), is sensitive to neutrino emission history through time of flight. We show that the constant time approximation, commonly used in calculating the neutrino halo, does not capture the spatiotemporal evolution of the halo neutrino population and that correcting for time of flight can produce conditions which may trigger fast neutrino flavor conversion. We also find that there exists a window of time early in all CCSNe where the neutrino halo population is sufficiently small that it may be negligible. This suggests that collective neutrino oscillation calculations which neglect the Halo may be well founded at sufficiently early times.

    ↳ astro-ph.HEhep-phPRD(2020)·29 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.