Wed·Oct 2, 2019Wednesday·October 2, 2019

1. 01*

   A landscape solution to the SUSY flavor and CP problems

   Howard Baer🇺🇸 · Vernon Barger🇺🇸 · Dibyashree Sengupta🇺🇸

   In a fertile patch of the string landscape which includes the Minimal Supersymmetric Standard Model (MSSM) as the low energy effective theory, rather general arguments from Douglas suggest a power-law statistical selection of soft breaking terms (m(soft)^n where n=2n_F+n_D-1 with n_F the number of hidden sector F-SUSY breaking fields and n_D the number of D-term SUSY breaking fields). The statistical draw towards large soft terms must be tempered by requiring an appropriate breakdown of electroweak (EW) symmetry with no contributions to the weak scale larger than a factor 2-5 of its measured value, lest one violates the (anthropic) atomic principle. Such a simple picture of stringy naturalness generates a light Higgs boson with mass m_h~ 125 GeV with sparticles (other than higgsinos) typically beyond LHC reach. Then we expect first and second generation matter scalars to be drawn independently to the tens of TeV regime where the upper cutoff arises from two-loop RGE terms which drive third generation soft masses towards tachyonic values. Since the upper bounds on m_0(1,2) are the same for each generation, and flavor independent, then these will be drawn toward quasi-degenerate values. This mechanism leads to a natural mixed decoupling/quasi-degeneracy solution to the SUSY flavor problem and a decoupling solution to the SUSY CP problem.

   hep-phPRResearch(2019)·40 citations
2. 02*

   Confronting minimal freeze-in models with the LHC

   G. Bélanger🇫🇷 · N. Desai🇫🇷 · A. Goudelis🇫🇷 · J. Harz🇩🇪 · A. Lessa🇧🇷 · J. M. No🇪🇸 · A. Pukhov🇷🇺 · S. Sekmen🇰🇷 · D. Sengupta🇺🇸 · B. Zaldivar🇫🇷 · J. Zurita🇩🇪

   We present a class of dark matter models, in which the dark matter particle is a feebly interacting massive particle (FIMP) produced via the decay of an electrically charged and/or colored parent particle. Given the feeble interaction, dark matter is produced via the freeze-in mechanism and the parent particle is long-lived. The latter leads to interesting collider signatures. We study current LHC constrains on our models arising from searches for heavy charged particles, disappearing tracks, displaced leptons and displaced vertices. We demonstrate not only that collider searches can be a powerful probe of the freeze-in dark matter models under consideration, but that an observation can lead as well to interesting insights on the reheating temperature and thus on the validity of certain baryogenesis models.

   hep-ph0 citations
3. 03*

   Proper time evolution of magnetic susceptibility in a magnetized quark-gluon plasma

   S.M.A. Tabatabaee🇮🇷 · N. Sadooghi🇮🇷

   In ultrarelativistic heavy-ion collisions, enormous magnetic fields are generated because of fast-moving charged particles. In the presence of these magnetic fields, the spin of particles is aligned either in the parallel or in the antiparallel direction with respect to the direction of the magnetic field. A finite magnetization is thus produced. It is known that a finite magnetic susceptibility, ${\chi }_m$, changes the evolution of the energy density of the quark-gluon plasma (QGP), which is believed to be created in these collisions. Depending on whether the system under consideration is a paramagnetic (${\chi }_m>0$) or diamagnetic (${\chi }_m<0$) fluid, it slows down or speeds up the decay of the energy density, and affects other thermodynamic quantities. In general, one expects that the magnetic susceptibility depends on the magnetic field and temperature. Bearing in mind that these parameters evolve with the evolution of the fluid, a nonuniform magnetic susceptibility in this system is thus expected. In this work, we first determine ${\chi }_m$ by using a certain analogy to the standard anisotropic kinetic theory, where the one-particle distribution function is replaced by the corresponding anisotropic distribution function. We then determine the proper time dependence of the magnetic susceptibility in the framework of the ideal transverse magnetohydrodynamics. We also study the effect of dissipation on the evolution of ${\chi }_m$.

   hep-phhep-thnucl-thPoS(2018)·0 citations
4. 04*

   Probing the Electroweak Sphaleron with Gravitational Waves

   Ruiyu Zhou🇨🇳 · Ligong Bian🇨🇳 · Huai-Ke Guo🇺🇸

   We present the relation between the sphaleron energy and the gravitational wave signals from a first order electroweak phase transition. The crucial ingredient is the scaling law between the sphaleron energy at the temperature of the phase transition and that at zero temperature. We estimate the baryon number preservation criterion, and observe that for a sufficiently strong phase transition, it is possible to probe the electroweak sphaleron using measurements of future space-based gravitational wave detectors.

   hep-phastro-ph.COhep-thPRD(2020)·46 citations
5. 05*

   A new angle on an old problem: Helicity approach to neutron beta decay in the Standard Model

   Stefan Groote🇪🇪 · Jürgen G. Körner🇩🇪 · Blaženka Melić🇭🇷

   We elaborate on the dichotomy between the description of the semileptonic decays of heavy hadrons on the one hand and the semileptonic decays of light hadrons such as neutron $\beta$ decays on the other hand. For example, almost without exception the semileptonic decays of heavy baryons are described in cascade fashion as a sequence of two two-body decays $B_1\to B_2+W_{\mathrm{off}-\mathrm{shell}}$ and $W_{\mathrm{off}-\mathrm{shell}}\to \ell +{\nu }_{\ell }$ whereas neutron $\beta$ decays are analyzed as true three-body decays $n\to p+e^{-}+{\bar{\nu }}_e$. Within the cascade approach it is possible to define a set of seven angular observables for polarized neutron $\beta$ decays as well as the longitudinal, transverse and normal polarization of the decay electron. We determine the dependence of the observables on the usual vector and axial vector form factors. In order to be able to assess the importance of recoil corrections we expand the rate and the $q^2$ averages of the observables up to NLO and NNLO in the recoil parameter $\delta =(M_n-M_p)/(M_n+M_p)=0.689\cdot 10^{-3}$. Remarkably, we find that the rate and three of the four parity conserving polarization observables that we analyze are protected from NLO recoil corrections when the second class current contributions are set to zero.

   hep-phnucl-thEPJC(2019)·5 citations
6. 06*

   Flavour and Higgs compositeness: present and "near" future

   Riccardo Barbieri🇮🇹

   Flavour physics, from now up to the operation of the next high energy collider, will be an important tool for BSM searches at the TeV scale. Although far from exhaustive, a particularly relevant case is represented by the possibility that the Higgs be a composite Pseudo-Nambu-Goldstone-Boson (PNGB) at a scale $l_H=1/m_{\ast }$. While a totally model-independent assessment of the potential of flavour physics in this case is impossible, here we illustrate what is likely to be a minimal sensitivity on $m_{\ast }$ by considering suitable examples.\

   hep-ph5 citations
7. 07*

   Lorentz and CPT Tests using Penning Traps

   Yunhua Ding🇺🇸

   The theoretical prospects for quantum electrodynamics with Lorentz-violating operators of mass dimensions up to six are revisited in this work. The dominant effects due to Lorentz and CPT violation are studied in measurements of magnetic moments of particles confined in Penning traps. Using recently reported experimental results, new coefficients for Lorentz violation are constrained and existing bounds of various coefficients are improved.

   hep-phSymmetry(2019)·19 citations
8. 08*

   Quintessence Axion Dark Energy and a Solution to the Hubble Tension

   Gongjun Choi🇨🇳 · Motoo Suzuki🇨🇳 · Tsutomu T. Yanagida🇯🇵

   We present a model in which the question about a nature of the dark energy and the recently raised Hubble tension can be addressed at once. We consider the electroweak axion in the minimal supersymmetric standard model where the axion energy density is identified with the observed dark energy. Along with this, imposing a gauged $Z_{10}$ symmetry makes it possible to have a gravitino dark matter whose mass amounts to $\sim \mathcal{O}(1)\mathrm{GeV}$. We find that the gravitino with mass $\sim \mathcal{O}(1)\mathrm{GeV}$ can be a good candidate of a decaying dark matter of which decay after recombination can reconcile discrepancy in local measurements of the Hubble expansion rate $H_0$ and that inferred from the cosmic microwave background observation.

   hep-phastro-ph.COPLB(2020)·46 citations
9. 09*

   Cosmological Time Evolution of the Higgs Mass and Gravitational Waves

   Xavier Calmet🇬🇧

   We point out that gravitational wave detectors such as LISA have the potential of probing a cosmological time evolution of the Higgs boson self-coupling constant $\lambda$ and thus the Higgs boson's mass $m_H=\sqrt{2\lambda }v$. The phase transition of the Standard Model could have been a first order one if the Higgs mass was below 72 GeV at a temperature $T_{\star }\ge 100$ GeV. Gravitational waves could thus have been produced during the electroweak phase transition. A discovery by LISA of a stochastic background of gravitational waves with a characteristic frequency $k_{\star }\ge 10^{-5}$ Hz could be interpreted as a sign that the Higgs boson self-coupling constant was smaller in the past. This interpretation would be particularly tempting if the Large Hadron Collider did not discover any physics beyond the Standard Model by the time such waves are seen. The same mechanism could also account for baryogenesis.

   hep-phgr-qchep-thInt.J.Mod.Phys.A(2020)·2 citations
10. 10*

    The Warm Dark Matter Doorframe for Light Dark Matter Direct Detection Experiments

    Ran Huo🇺🇸 · Tao Xu🇨🇳

    If dark matter has even been in sufficient thermal contact with the visible sector and sufficiently light ($m_{\chi }\lesssim \mathcal{O}(10)\text{keV}$), the thermal motion inherited from the visible sector will cause significant free streaming effect which is subject to the structure formation constraint, similar to the benchmark thermal warm dark matter model. Here we identify the interaction responsible for such thermal contact to be the interaction probed by the deep underground dark matter direct detection experiments. With the kinetic decoupling technique on the $m_{\chi }$ vs. $\sigma$ plot we determine the bound shape in detail, and find that recasting the current Lyman-$\alpha$ bound gives a constraint of $m_{\chi }\gtrsim 73\text{keV}$, and it gets relaxed to $m_{\chi }\gtrsim 35\text{keV}$ for a smaller cross section of $\sigma <10^{-46}{\text{cm}}^2$ with some model dependence. That can be taken as a generic ``no go'' constraint for light dark matter direct detection experiments, and the known caveats are if dark matter is axion-like with an early Bose-Einstein condensation form, or if there is Brownian motion protection of the free streaming.

    hep-phastro-ph.COhep-ex0 citations
11. 11*

    Probing Bosonic Stars with Atomic Clocks

    Chris Kouvaris🇩🇰 · Eleftherios Papantonopoulos🇬🇷 · Lauren Street🇺🇸 · L.C.R. Wijewardhana🇺🇸

    Dark Matter could potentially manifest itself in the form of asymmetric dark stars. In this paper we entertain the possibility of probing such asymmetric bosonic dark matter stars by the use of atomic clocks. If the dark sector connects to the standard model sector via a Higgs or photon portal, the interior of boson stars that are in a Bose-Einstein condensate state can change the values of physical constants that control the timing of atomic clock devices. Dilute asymmetric dark matter boson stars passing through the Earth can induce frequency shifts that can be observed in separated Earth based atomic clocks. This gives the opportunity to probe a class of dark matter candidates that for the moment cannot be detected with any different conventional method.

    hep-phastro-ph.COgr-qchep-th+1PRD(2020)·13 citations
12. 12*

    Covert symmetries in the neutrino mass matrix

    Fredrik Björkeroth🇮🇹 · Luca Di Luzio🇮🇹 · Federico Mescia🇪🇸 · Enrico Nardi🇮🇹

    The flavour neutrino puzzle is often addressed by considering neutrino mass matrices $m$ with a certain number of vanishing entries ($m_{ij}=0$ for some values of the indices), since a reduction in the number of free parameters increases the predictive power. Symmetries that can enforce textures zero can also enforce a more general type of conditions $f(m_{ij})=0$ with $f$ some function of the matrix elements $m_{ij}$. In this case $m$ can have all entries non-vanishing with no reduction in its predictive power. We classify all generation-dependent $U(1)$ symmetries which, in the presence of two leptonic Higgs doublets, can reduce the number of independent high-energy parameters of type-I seesaw to the minimum number compatible with non-vanishing neutrino mixings and CP violation. These symmetries are broken above the scale where the effective operator is generated and can thus remain covert, in the sense that no explicit evidence of the symmetry can be read off the neutrino mass matrix, and different symmetries can give rise to the same low-energy structure. We find that only two cases are viable: one yields a structure with two zero-textures already considered in the literature, the other has no zero-textures and has never been considered before. It predicts normal ordering, a lightest neutrino mass $\sim 10$ meV, a Dirac phase $\delta \sim \frac{3\pi }{2}$ and definite values for the Majorana phases.

    hep-phJHEP(2020)·8 citations
13. 13*

    Pion nucleus Drell-Yan process and parton transverse momentum in the pion

    A. Courtoy🇲🇽

    During the INT-18-3 workshop, we presented an analysis of unpolarized Drell-Yan pair production in pion-nucleus scattering with a particular focus into the pion Transverse Momentum Distributions in view of the future Electron Ion Collider. The transverse distributions of the pion calculated in a Nambu--Jona-Lasinio framework, with Pauli-Villars regularization, were used. The pion Transverse Momentum Distributions evolved up to next-to-leading logarithmic accuracy is then tested against the transverse momentum spectrum of dilepton pairs up to a transverse momentum of 2 GeV. We found a fair agreement with available pion-nucleus data. This contribution joins common efforts from the TMD and the pion structure communities for the Electron Ion Collider.

    hep-ph0 citations
14. 14*

    Electromagnetic Solitons in Quantum Vacuum

    S. V. Bulanov🇨🇿 · P. V. Sasorov🇨🇿 · F. Pegoraro🇮🇹 · H. Kadlecova🇨🇿 · S. S. Bulanov🇺🇸 · T. Zh. Esirkepov🇯🇵 · N. N. Rosanov🇷🇺 · G. Korn🇨🇿

    In the limit of extremely intense electromagnetic fields the Maxwell equations are modified due to the photon-photon scattering that makes the vacuum refraction index depend on the field amplitude. In presence of electromagnetic waves with small but finite wavenumbers the vacuum behaves as a dispersive medium. We show that the interplay between the vacuum polarization and the nonlinear effects in the interaction of counter-propagating electromagnetic waves can result in the formation of Kadomtsev-Petviashvily solitons and, in one-dimension configuration, of Korteveg-de-Vries type solitons that can propagate over a large distance without changing their shape.

    ↳ physics.plasm-phhep-phnlin.PSPRD(2020)·15 citations
15. 15*

    Unique Access to u-Channel Physics: Exclusive Backward-Angle Omega Meson Electroproduction

    W.B. Li🇺🇸 · G.M. Huber🇨🇦 · H.P. Blok🇳🇱 · D. Gaskell🇺🇸 · T. Horn🇺🇸 · K. Semenov-Tian-Shansky🇷🇺 · B. Pire🇫🇷 · L. Szymanowski🇵🇱 · J.-M. Laget🇺🇸 · K. Aniol🇺🇸 · J. Arrington🇺🇸 · E.J. Beise🇺🇸 and 44 other authors

    Backward-angle meson electroproduction above the resonance region, which was previously ignored, is anticipated to offer unique access to the three quark plus sea component of the nucleon wave function. In this letter, we present the first complete separation of the four electromagnetic structure functions above the resonance region in exclusive omega electroproduction off the proton, e + p -> e' + p + omega, at central Q^2 values of 1.60, 2.45 GeV^2 , at W = 2.21 GeV. The results of our pioneering -u ~ -u min study demonstrate the existence of a unanticipated backward-angle cross section peak and the feasibility of full L/T/LT/TT separations in this never explored kinematic territory. At Q^2 =2.45 GeV^2 , the observed dominance of sigma_T over sigma_L, is qualitatively consistent with the collinear QCD description in the near-backward regime, in which the scattering amplitude factorizes into a hard subprocess amplitude and baryon to meson transition distribution amplitudes (TDAs): universal non-perturbative objects only accessible through backward angle kinematics.

    ↳ nucl-exhep-exhep-phnucl-thPRL(2019)·29 citations
16. 16*

    Trans-Planckian Censorship, Inflation and Dark Matter

    Tommi Tenkanen🇺🇸

    If the inflationary phase lasted longer than the minimal period, the length scales observed today originate from modes that were smaller than the Planck length during inflation. It was recently argued that this "trans-Planckian problem" can never arise in a consistent string theory framework, which places a stringent constraint on the energy scale of inflation, $V^{1/4}\lesssim 10^9$ GeV. In this paper, we show that this requirement corresponds to a very small Hubble scale during inflation, $H_{\inf }\lesssim 1$ GeV, and therefore has serious consequences on scenarios where the dark matter density was generated by amplification of quantum fluctuations during inflation. We also present a class of inflationary models which both satisfy the above limit for the scale of inflation and are in perfect agreement with observational data.

    ↳ astro-ph.COgr-qchep-phPRD(2020)·70 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.