Wed·Jun 27, 2018Wednesday·June 27, 2018

1. 01*

   A Forward Branching Phase Space Generator for Hadron colliders

   Terrance M. Figy (Department of Mathematics, Statistics, and Physics, Wichita State University, Wichita, Kansas, USA)🇺🇸 · Walter T. Giele (Theory Group, Fermilab, Batavia, USA)🇺🇸

   In this paper we develop a projective phase space generator appropriate for hadron collider geometry. The generator integrates over bremsstrahlung events which project back to a single, fixed Born event. The projection is dictated by the experimental jet algorithm allowing for the forward branching phase space generator to integrate out the jet masses and initial state radiation. When integrating over the virtual and bremsstrahlung amplitudes this results in a single K-factor, assigning an event probability to each Born event. This K-factor is calculable as a perturbative expansion in the strong coupling constant. One can build observables from the Born kinematics, giving identical results to tradi- tional observables as long as the observable does not depend on the infrared sensitive jet mass or initial state radiation.

   hep-phJHEP(2018)·10 citations
2. 02*

   Dynamical projections for the visualization of PDFSense data

   Dianne Cook🇦🇺 · Ursula Laa🇦🇺 · German Valencia🇦🇺

   A recent paper on visualizing the sensitivity of hadronic experiments to nucleon structure [1] introduces the tool PDFSense which defines measures to allow the user to judge the sensitivity of PDF fits to a given experiment. The sensitivity is characterized by high-dimensional data residuals that are visualized in a 3-d subspace of the 10 first principal components or using t-SNE [2]. We show how a tour, a dynamic visualisation of high dimensional data, can extend this tool beyond 3-d relationships. This approach enables resolving structure orthogonal to the 2-d viewing plane used so far, and hence finer tuned assessment of the sensitivity.

   hep-phhep-exphysics.data-anEPJC(2018)·7 citations
3. 03*

   Emergent symmetries of the Standard Model

   P.J. Mulders🇳🇱

   We show how, using multipartite entanglement, the symmetries among bosons and fermions of the Standard Model of particle physics emerge. Fermions belong to tripartite maximally entangled classes starting with basic chiral right and left states. Quarks and leptons belong to different classes, with only leptons appearing as asymptotic states in three space dimensions. The Higgs boson is the scalar mode with a nonvanishing vacuum expectation value, other bosons are as usual linked to symmetry generators.

   hep-phPLB(2018)·2 citations
4. 04*

   Large off-shell effects in the ${\bar{D}}^{\ast }$ contribution to $B\to \bar{D}\pi \pi$ and $B\to \bar{D}\pi \bar{\ell }{\nu }_{\ell }$ decays.}}

   A. Le-Yaouanc🇫🇷 · J.-P. Leroy🇫🇷 · P. Roudeau🇫🇷

   We stress that, although the $D^{\ast }$ is very narrow (one hundred of keV), the difference between the full $D^{\ast }$ contribution to $B\to \bar{D}\pi \pi$ and its zero width limit, which stems from the resonance tail, is surprisingly large~: several percents. This phenomenon is a general effect which appears when considering the production of particles that are coupled to an intermediate virtual state, stable or not, and it persists whether the width is large or not. The effects of various cuts and of the inclusion of damping factors at the strong and weak vertices are discussed. It is shown how the zero width limit, needed to compare with theoretical expectations, can be extracted. One also evaluates the virtual $D_V^{\ast }$ contribution, which comes out roughly as expected from theory, but which is however much more dependent on cuts and uncontrollable "off-shell" effects. We suggest a way to estimate the impact of the damping factors.

   hep-phhep-exPRD(2019)·10 citations
5. 05*

   Critical acoustics and singular bulk viscosity of quark matter

   B.O. Kerbikov🇷🇺

   We examine the behavior of sound attenuation and bulk viscosity near the 2'nd order QCD phase transition at finite density. A dynamical model is presented describing the coupled evolution of sound mode and a slow mode of fluctuations.

   hep-ph3 citations
6. 06*

   A predictive model of radiative neutrino mass with gauged $U(1{)}_{B-2L_{{\ell }_2}-L_{{\ell }_1}}$ symmetry

   Takaaki Nomura🇰🇷 · Hiroshi Okada🇰🇷

   We propose a predictively radiative neutrino mass model with gauged $U(1{)}_{B-2L_{{\ell }_2}-L_{{\ell }_1}}$ symmetry in which we successfully realize two-zero textures of neutrino mass matrix depending on charge assignment for leptons and the singlet scalar fields. Then some correlations of neutrino parameters are shown where we take mass structure given by $({\ell }_2,{\ell }_1)=(\mu ,\tau )$ or $(\mu ,e)$ as a representative case. Furthermore we discuss phenomenology of the model such as lepton flavor violations, collider physics, and dark matter candidate.

   hep-ph4 citations
7. 07*

   Extension of the electrodynamics in the presence of the axion and dark photon

   Fa Peng Huang🇰🇷 · Hye-Sung Lee🇰🇷

   We present the extended electrodynamics in the presence of the axion and dark photon. We derive the extended versions of Maxwell's equations and dark Maxwell's equations (for both massive and massless dark photons) as well as the wave equations. We discuss the implications of this extended electrodynamics including the enhanced effects in the particle conversions under the external magnetic or dark magnetic field. We also discuss the recently reported anomaly in the redshifted 21cm spectrum using the extended electrodynamics.

   hep-phInt.J.Mod.Phys.A(2019)·11 citations
8. 08*

   QCD determination of the magnetic field dependence of QCD and hadronic parameters

   C. A. Dominguez🇿🇦 · M. Loewe🇨🇱 · Cristian Villavicencio🇨🇱

   A set of four Finite Energy QCD sum rules are used to determine the magnetic field dependence of the sum of the up- and down-quark masses of QCD, $(m_u+m_d)$, the pion decay constant $f_{\pi }$, the pion mass $m_{\pi }$, the gluon condensate, $⟨0|{\alpha }_s{G}^2|0⟩$, and the squared energy threshold for the onset of perturbative QCD, $s_0$, related to the Polyakov loop of lattice QCD.

   hep-phnucl-thPRD(2018)·29 citations
9. 09*

   On stochastically sampling color configurations

   Joshua Isaacson🇺🇸 · Stefan Prestel🇺🇸

   Parton shower algorithms are key components of theoretical predictions for high-energy collider physics. Work towards more accurate parton shower algorithms is thus pursued along many different avenues. The systematic treatment of subleading color corrections in parton shower algorithms is however technically challenging and remains elusive. In this article, we present an efficient and numerically stable algorithm to sample color configurations at fixed $N_C=3$, using the correct color factor including subleading corrections with a parton shower. The algorithm is implemented as stand-alone program that can be interfaced to the PYTHIA event generator. Preliminary comparisons to to LEP data are presented.

   hep-phPRD(2019)·37 citations
10. 10*

    Neutron Dark Matter Decays

    A. N. Ivanov🇦🇹 · R. Höllwieser🇦🇹 · N. I. Troitskaya🇦🇹 · M. Wellenzohn🇦🇹 · Ya. A. Berdnikov🇷🇺

    We analyse the discrepancy between the neutron lifetimes measured in the bottle and beam experiments. Following Fornal and Grinstein (Phys. Rev. Lett. 120, 191801 (2018)) we propose an explanation of such a puzzle by the dark matter channels of the neutron decay. However, unlike Fornal and Grinstein in addition to the dark matter decay channel n -> \chi + e^- + e^+, where \chi is a dark matter Dirac fermion and (e^-e^+) is an electron--positron pair, we assume the existence of the dark matter channel n -> chi + \nu_e + \bar{\nu}_e, where \nu_e \bar{\nu}_e is the electron neutrino-antineutrino pair. This allows to describe the discrepancy between the measurements of the neutron lifetime even in case of an unobservability of the dark matter decay channel n -> \chi + e^- + e^+, which may be below the reaction threshold. The existence of the coupling n -> \chi + e^- + e^+ can be observed experimentally by measuring electron-neutron scattering e^- + n -> \chi + e^- at very low electron energies, induced with the strength as of the decay n -> \chi + \nu_e + \bar{\nu}_e$. We propose a gauge invariant quantum field theory model with SU_L(2)\times U_R(1) \times U_R'(1)\times U''_L(1) symmetry for the UV completion of the effective (n\chi \ell \bar{\ell}) interaction, where \ell(\bar{\ell}) is electron (positron) or neutrino(antineutrino).

    hep-phgr-qcnucl-ex20 citations
11. 11*

    A model calculation of double parton distribution functions of the pion

    Matteo Rinaldi🇪🇸 · Sergio Scopetta🇮🇹 · Marco Traini🇮🇹 · Vicente Vento🇪🇸

    Two-parton correlations in the pion are investigated in terms of double parton distribution functions. A Poincaré covariant Light-Front framework has been adopted. As non perturbative input, the pion wave function obtained within the so-called soft-wall AdS/QCD model has been used. Results show how novel dynamical information on the structure of the pion, not accessible through one-body parton distribution, are encoded in double parton distribution functions.

    hep-phEPJC(2018)·22 citations
12. 12*

    Calculations of the Sommerfeld Effect in a Unified Wave Function Framework

    Yi-Lei Tang🇰🇷 · Gao-Liang Zhou🇨🇳

    In this paper, we suggest a method of a complete calculation of the Sommerfeld effect in both the s-wave and p-wave annihilation situations. The basic idea is to uniformly consider the equal-time Beth-Salpeter wave functions of both the dark matter and the final state particles, then short-distance interactions can be parametrized as a cross-term considering the equations. Solving these equations will result in the complete formulas of the cross sections with the Sommerfeld effects.

    hep-phhep-thPRD(2019)·4 citations
13. 13*

    SIMPs through the axion portal

    Yonit Hochberg🇮🇱 · Eric Kuflik🇮🇱 · Robert McGehee🇺🇸 · Hitoshi Murayama🇺🇸 · Katelin Schutz🇺🇸

    Dark matter could be a thermal relic comprised of strongly interacting massive particles (SIMPs), where $3\to 2$ interactions set the relic abundance. Such interactions generically arise in theories of chiral symmetry breaking via the Wess-Zumino-Witten term. In this work, we show that an axion-like particle can successfully maintain kinetic equilibrium between the dark matter and the visible sector, allowing the requisite entropy transfer that is crucial for SIMPs to be a cold dark matter candidate. Constraints on this scenario arise from beam dump and collider experiments, from the cosmic microwave background, and from supernovae. We find a viable parameter space when the axion-like particle is close in mass to the SIMP dark matter, with strong-scale masses of order a few hundred MeV. Many planned experiments are set to probe the parameter space in the near future.

    hep-phastro-ph.COPRD(2018)·128 citations
14. 14*

    Reconciling $B$-decay anomalies with neutrino masses, dark matter and constraints from flavour violation

    Chandan Hati🇫🇷 · Girish Kumar🇮🇳 · Jean Orloff🇫🇷 · Ana M. Teixeira🇫🇷

    Motivated by an explanation of the $R_{K^{(\ast )}}$ anomalies, we propose a Standard Model extension via two scalar SU(2)${}_L$ triplet leptoquarks and three generations of triplet Majorana fermions. The gauge group is reinforced by a $Z_2$ symmetry, ensuring the stability of the lightest $Z_2$-odd particle, which is a potentially viable dark matter candidate. Neutrino mass generation occurs radiatively (at the three-loop level), and leads to important constraints on the leptoquark couplings to leptons. We consider very generic textures for the flavour structure of the $h_1$ leptoquark Yukawa couplings, identifying classes of textures which succeed in saturating the $R_{K^{(\ast )}}$ anomalies. We subsequently carry a comprehensive analysis of the model's contributions to numerous high-intensity observables such as meson oscillations and decays, as well as charged lepton flavour violating processes, which put severe constraints on the flavour structure of these leptoquark extensions. Our findings suggest that the most constraining observables are $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ decays, and charged lepton flavour violating $\mu -e$ conversion in nuclei (among others). Nevertheless, for several classes of flavour textures and for wide mass regimes of the new mediators (within collider reach), this Standard Model extension successfully addresses neutrino mass generation, explains the current $R_{K^{(\ast )}}$ tensions, and offers a viable dark matter candidate.

    hep-phJHEP(2018)·54 citations
15. 15*

    Standard versus Non-Standard CP Phases in Neutrino Oscillation in Matter with Non-Unitarity

    Ivan Martinez-Soler🇺🇸 · Hisakazu Minakata🇺🇸

    We formulate a perturbative framework for the flavor transformation of the standard three active neutrinos but with non-unitary flavor mixing matrix, a system which may be relevant for leptonic unitarity test. We use the $\alpha$ parametrization of the non-unitary matrix and take its elements ${\alpha }_{\beta \gamma }$ ($\beta ,\gamma =e,\mu ,\tau$) and the ratio $ϵ\simeq \Delta m_{21}^2/\Delta m_{31}^2$ as the small expansion parameters. Qualitatively new two features that hold in all the oscillation channels are uncovered in the probability formula obtained to first order in the expansion: (1) The phases of the complex $\alpha$ elements always come in into the observable in the particular combination with the $\nu$SM CP phase $\delta$ in the form $[e^{-i\delta }{\bar{\alpha }}_{\mu e},e^{-i\delta }{\bar{\alpha }}_{\tau e},{\bar{\alpha }}_{\tau \mu }]$ under the PDG convention of unitary $\nu$SM mixing matrix. (2) The diagonal $\alpha$ parameters appear in particular combinations $\left(a/b-1\right){\alpha }_{ee}+{\alpha }_{\mu \mu }$ and ${\alpha }_{\mu \mu }-{\alpha }_{\tau \tau }$, where $a$ and $b$ denote, respectively, the matter potential due to CC and NC reactions. This property holds only in the unitary evolution part of the probability, and there is no such feature in the genuine non-unitary part, while the $\delta$ - $\alpha$ parameter phase correlation exists for both. The reason for such remarkable stability of the phase correlation is discussed.

    hep-phPTEP(2020)·28 citations
16. 16*

    DGLAP evolution for DIS diffraction production of high masses

    Carlos Contreras (UTFSM)🇨🇱 · Eugene Levin (Tel Aviv U./UTFSM)🇮🇱 · Rodrigo Meneses (U.de Valparaiso)🇨🇱 · Irina Potashnikova (UTFSM)🇨🇱

    In this paper we develop the DGLAP evolution for the system of produced gluons in the process of diffractive production in DIS, directly from the evolution equation in Color Glass Condensate approach. We are able to describe the available experimental data with small value of the QCD coupling ($\overline{{\alpha }_S}\approx 0.1$). We conclude that in diffractive production, we have a dilute system of emitted gluons and in the order to describe them, we need to develop the next-to-leading order approach in perturbative QCD.

    hep-phEPJC(2018)·7 citations
17. 17*

    The Fundamental Need for a SM Higgs and the Weak Gravity Conjecture

    Eduardo Gonzalo🇪🇸 · Luis E. Ibáñez🇪🇸

    Compactifying the SM down to 3D or 2D one may obtain AdS vacua depending on the neutrino mass spectrum. It has been recently shown that, by insisting in the absence of these vacua, as suggested by {\it Weak Gravity Conjecture} (WGC) arguments, intriguing constraints on the value of the lightest neutrino mass and the 4D cosmological constant are obtained. For fixed Yukawa coupling one also obtains an upper bound on the EW scale $⟨H⟩\lesssim {\Lambda }_4^{1/4}/Y_{{\nu }_i}$,where ${\Lambda }_4$ is the 4D cosmological constant and $Y_{{\nu }_i}$ the Yukawa coupling of the lightest (Dirac) neutrino. This bound may lead to a reassessment of the gauge hierarchy problem. In this letter, following the same line of arguments, we point out that the SM without a Higgs field would give rise to new AdS lower dimensional vacua. Absence of latter would require the very existence of the SM Higgs. Furthermore one can derive a lower bound on the Higgs vev $⟨H⟩\gtrsim {\Lambda }_{\text{QCD}}$ which is required by the absence of AdS vacua in lower dimensions. The lowest number of quark/lepton generations in which this need for a Higgs applies is three, giving a justification for family replication. We also reassess the connection between the EW scale, neutrino masses and the c.c. in this approach. The EW fine-tuning is here related to the proximity between the c.c. scale ${\Lambda }_4^{1/4}$ and the lightest neutrino mass $m_{{\nu }_i}$ by the expression $\frac{\Delta H}{H}\lesssim \frac{(a{\Lambda }_4^{1/4}-m_{{\nu }_i})}{m_{{\nu }_i}}.$ We emphasize that all the above results rely on the assumption of the stability of the AdS SM vacua found.

    ↳ hep-thhep-phPLB(2018)·37 citations
18. 18*

    On the Cosmological Implications of the String Swampland

    Prateek Agrawal🇺🇸 · Georges Obied🇺🇸 · Paul J. Steinhardt🇺🇸 · Cumrun Vafa🇺🇸

    We study constraints imposed by two proposed string Swampland criteria on cosmology. These criteria involve an upper bound on the range traversed by scalar fields as well as a lower bound on $|{\nabla }_{\varphi }V|/V$ when $V>0$. We find that inflationary models are generically in tension with these two criteria. Applying these same criteria to dark energy in the present epoch, we find that specific quintessence models can satisfy these bounds and, at the same time, satisfy current observational constraints. Assuming the two Swampland criteria are valid, we argue that the universe will undergo a phase transition within a few Hubble times. These criteria sharpen the motivation for future measurements of the tensor-to-scalar ratio $r$ and the dark energy equation of state $w$, and for tests of the equivalence principle for dark matter.

    ↳ hep-thastro-ph.COgr-qchep-phPLB(2018)·625 citations
19. 19*

    Behind Horndeski: Structurally Robust Higher Derivative EFTs

    Luca Santoni🇳🇱 · Enrico Trincherini🇮🇹 · Leonardo G. Trombetta🇮🇹

    Higher derivative scalar interactions can give rise to interesting cosmological scenarios. We present a complete classification of such operators that can yield sizeable effects without introducing ghosts and, at the same time, define an effective field theory robust under the inclusion of quantum corrections. A set of rules to power count consistently the coefficients of the resulting Lagrangian is provided by the presence of an approximate global symmetry. The interactions that we derive in this way contain a subset of the so-called Horndeski and beyond Horndeski theories. Our construction therefore provides a structurally robust context to study their phenomenology. Applications to dark energy/modified gravity and geodesically complete cosmologies are briefly discussed.

    ↳ hep-thastro-ph.COhep-phJHEP(2018)·37 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.