Fri·Aug 17, 2018Friday·August 17, 2018

1. 01*

   Multiplicity dependence of light nuclei production at LHC energies in the canonical statistical model

   Volodymyr Vovchenko🇩🇪 · Benjamin Donigus🇩🇪 · Horst Stoecker🇩🇪

   The statistical model with exact conservation of baryon number, electric charge, and strangeness - the Canonical Statistical Model (CSM) - is used to analyze the dependence of yields of light nuclei at midrapidity on charged pion multiplicity at the LHC. The CSM calculations are performed assuming baryon-symmetric matter, using the recently developed Thermal-FIST package. The light nuclei-to-proton yield ratios show a monotonic increase with charged pion multiplicity, with a saturation at the corresponding grand-canonical values in the high-multiplicity limit, in good qualitative agreement with the experimental data measured by the ALICE collaboration in pp and Pb-Pb collisions at different centralities and energies. Comparison with experimental data at low multiplicities shows that exact conservation of charges across more than one unit of rapidity and/or a chemical freeze-out temperature which decreases with the charged pion multiplicity improves agreement with the data.

   hep-phnucl-exnucl-thPLB(2018)·105 citations
2. 02*

   Processes that break baryon number by two units and the Majorana nature of the neutrino

   Susan Gardner🇺🇸 · Xinshuai Yan🇺🇸

   We employ the simplest possible models of scalar-fermion interactions that are consistent with the gauge symmetries of the Standard Model and permit no proton decay to analyze the connections possible among processes that break baryon number by two units. In this context we show how the observation of $n$-$\bar{n}$ oscillations and of a pattern of particular nucleon-antinucleon conversion processes --- all accessible through e-d scattering --- namely, selecting from $e^{-}p\to e^{+}\bar{p}$, $e^{-}p\to \bar{n}\bar{\nu }$, $e^{-}n\to \bar{p}\bar{\nu }$, and $e^{-}n\to e^{-}\bar{n}$ would reveal that the decay ${\pi }^{-}{\pi }^{-}\to e^{-}{e}^{-}$ must occur also. This latter process is the leading contribution to neutrinoless double beta decay in nuclei mediated by new short-distance physics, in contrast to that mediated by light Majorana neutrino exchange. The inferred existence of ${\pi }^{-}{\pi }^{-}\to e^{-}{e}^{-}$ would also reveal the Majorana nature of the neutrino, though the absence of this inference would not preclude it.

   hep-phnucl-thPLB(2019)·21 citations
3. 03*

   Bayesian extraction of jet energy loss distributions in heavy-ion collisions

   Yayun He (CCNU, LBNL)🇨🇳 · Long-Gang Pang (LBNL, UCB)🇺🇸 · Xin-Nian Wang (CCNU, LBNL)🇺🇸

   Based on the factorization in perturbative QCD, a jet cross sections in heavy-ion collisions can be expressed as a convolution of the jet cross section in $p+p$ collisions and a jet energy loss distribution. Using this simple expression and the Markov Chain Monte Carlo method, we carry out Bayesian analyses of experimental data on jet spectra to extract energy loss distributions for both single inclusive and $\gamma$-triggered jets in $Pb+Pb$ collisions with different centralities at two colliding energies at the Large Hadron Collider. The average jet energy loss has a dependence on the initial jet energy that is slightly stronger than a logarithmic form and decreases from central to peripheral collisions. The extracted jet energy loss distributions with a scaling behavior in $x=\Delta p_T/⟨\Delta p_T⟩$ have a large width. These are consistent with the linear Boltzmann transport model simulations, in which the observed jet quenching is caused on the average by only a few out-of-cone scatterings.

   hep-phhep-exnucl-exnucl-thPRL(2019)·62 citations
4. 04*

   Baryon-Lepton Duplicity as the Progenitor of Long-Lived Dark Matter

   Ernest Ma (UC Riverside and HKUST/JCIAS)🇺🇸

   In an $SU(2{)}_R$ extension of the standard model, it is shown how the neutral fermion $N$ in the doublet $(N,e{)}_R$ may be assigned baryon number $B=1$, in contrast to its $SU(2{)}_L$ counterpart $\nu$ in the doublet $(\nu ,e{)}_L$ which has lepton number $L=1$. This baryon-lepton duplicity allows a scalar $\sigma$ which couples to $N_L{N}_L$ to be long-lived dark matter.

   hep-phPLB(2019)·1 citation
5. 05*

   Further tests of special interactions of massive particles from the Z polarization rate in $e^{+}{e}^{-}\to Zt\bar{t}$ and in $e^{+}{e}^{-}\to Z{W}^{+}{W}^{-}$

   Fernand M. Renard🇫🇷

   We propose further tests of the occurence of scale dependent heavy particle masses (Z,W,t) and of strong final state interactions by comparing Z longitudinal polarization rates in different kinematical distributions of the $e^{+}{e}^{-}\to Zt\bar{t}$ and in $e^{+}{e}^{-}\to Z{W}^{+}{W}^{-}$ processes.

   hep-ph4 citations
6. 06*

   A Short Travel for Neutrinos in Large Extra Dimensions

   G. V. Stenico🇧🇷 · D. V. Forero🇧🇷 · O. L. G. Peres🇧🇷

   Neutrino oscillations successfully explain the flavor transitions observed in neutrinos produced in natural sources like the center of the sun and the earth atmosphere, and also from man-made sources like reactors and accelerators. These oscillations are driven by two mass-squared differences, solar and atmospheric, at the sub-eV scale. However, longstanding anomalies at short-baselines might imply the existence of new oscillation frequencies at the eV-scale and the possibility of this sterile state(s) to mix with the three active neutrinos. One of the many future neutrino programs that are expected to provide a final word on this issue is the Short-Baseline Neutrino Program (SBN) at FERMILAB. In this letter, we consider a specific model of Large Extra Dimensions (LED) which provides interesting signatures of oscillation of extra sterile states. We started re-creating sensitivity analyses for sterile neutrinos in the 3+1 scenario, previously done by the SBN collaboration, by simulating neutrino events in the three SBN detectors from both muon neutrino disappearance and electron neutrino appearance. Then, we implemented neutrino oscillations as predicted in the LED model and also we have performed sensitivity analysis to the LED parameters. Finally, we studied the SBN power of discriminating between the two models, the 3+1 and the LED. We have found that SBN is sensitive to the oscillations predicted in the LED model and have the potential to constrain the LED parameter space better than any other oscillation experiment, for $m_1^D<0.1\text{eV}$. In case SBN observes a departure from the three active neutrino framework, it also has the power of discriminating between sterile oscillations predicted in the 3+1 framework and the LED ones.

   hep-phhep-exJHEP(2018)·22 citations
7. 07*

   Global Constraints from RHIC and LHC on Transport Properties of QCD Fluids in CUJET/CIBJET Framework

   Shuzhe Shi🇺🇸 · Jinfeng Liao🇺🇸 · Miklos Gyulassy🇺🇸

   We report results of a comprehensive global ${\chi }^2$ analysis of nuclear collision data from RHIC (0.2 ATeV), LHC1 (2.76 ATeV), and recent LHC2 (5.02 ATeV) energies using the updated CUJET framework. The framework consistently combines viscous hydrodynamic fields predicted by VISHNU2+1 (validated with soft $p_T<2$~GeV bulk observables) and the DGLV theory of jet elastic and inelastic energy loss generalized to QGP fluids with an sQGMP color structure, including effective semi-QGP color electric quark and gluon as well as emergent color magnetic monopole degrees of freedom constrained by lattice QCD data. We vary the two control parameters of the model (the maximum value of the running QCD coupling, ${\alpha }_c$, and the ratio $c_m$ of color magnetic to electric screening scales) and calculate the global ${\chi }^2({\alpha }_c,c_m)$ compared with available jet fragment observables ($R_{AA},v_2$). A global ${\chi }^2<2$ minimum is found with ${\alpha }_c\approx 0.9\pm 0.1$ and $c_m\approx 0.25\pm 0.03$. Using CIBJET, the event-by-event (ebe) generalization of the CUJET framework, we show that ebe fluctuations in the initial conditions do not significantly alter our conclusions (except for $v_3$). An important theoretical advantage of the CUJET and CIBJET frameworks is not only its global ${\chi }^2$ consistency with jet fragment observables at RHIC and LHC and with non-perturbative lattice QCD data, but also its internal consistency of the constrained jet transport coefficient, $\hat{q}(E,T)/T^3$, with the near-perfect fluid viscosity to entropy ratio ($\eta /s\sim T^3/\hat{q}\sim 0.1-0.2$) property of QCD fluids near $T_c$ needed to account for the low $p_T<2$ GeV flow observables. Predictions for future tests at LHC with 5.44 ATeV Xe + Xe and 5.02 ATeV Pb + Pb are also presented.

   hep-phhep-latCPC(2019)·82 citations
8. 08*

   A unified leptoquark model confronted with lepton non-universality in $B$-meson decays

   Thomas Faber🇩🇪 · Matěj Hudec🇨🇿 · Michal Malinský🇨🇿 · Peter Meinzinger🇩🇪 · Werner Porod🇩🇪 · Florian Staub🇩🇪

   The anomalies in the $B$-meson sector, in particular $R_{K^{(\ast )}}$ and $R_{D^{(\ast )}}$, are often interpreted as hints for physics beyond the Standard Model. To this end, leptoquarks or a heavy $Z^{\prime }$ represent the most popular SM extensions which can explain the observations. However, adding these fields by hand is not very satisfactory as it does not address the big questions like a possible embedding into a unified gauge theory. On the other hand, light leptoquarks within a unified framework are challenging due to additional constraints such as lepton flavor violation. The existing accounts typically deal with this issue by providing estimates on the relevant couplings. In this letter we consider a complete model based on the $SU(4{)}_{\mathrm{C}}\otimes SU(2{)}_{\mathrm{L}}\otimes U(1{)}_{\mathrm{R}}$ gauge symmetry, a subgroup of $SO(10)$, featuring both scalar and vector leptoquarks. We demonstrate that this setup has, in principle, all the potential to accommodate $R_{K^{(\ast )}}$ and $R_{D^{(\ast )}}$ while respecting bounds from other sectors usually checked in this context. However, it turns out that $K_L\to e^{\pm }{\mu }^{\mp }$ severely constraints not only the vector but also the scalar leptoquarks and, consequently, also the room for any sizeable deviations of $R_{K^{(\ast )}}$ from 1. We briefly comment on the options for extending the model in order to conform this constraint. Moreover, we present a simple criterion for all-orders proton stability within this class of models.

   hep-phPLB(2018)·49 citations
9. 09*

   Neutrino propagation in media and axis of complete polarization

   A.E. Kaloshin🇷🇺 · D.M.Voronin🇷🇺

   We construct a spectral representation of neutrino propagator in moving matter or in external magnetic field. In both cases there exists fixed four-dimensional axis of polarization, such that the corresponding spin projectors commute with propagator. As a result, all eigenvalues of propagator and, consequently, dispersion laws for neutrino in media are classified according to spin projection onto this axis. Use of the found spin projectors simplifies essentially the eigenvalue problem and allows to build spectral representation of propagator in moving matter or external magnetic field in analogy with the vacuum propagator.

   hep-phEPJC(2019)·4 citations
10. 10*

    Exotic Tetraquark Mesons in Large-$N_c$ Limit: an Unexpected Great Surprise

    Wolfgang Lucha🇦🇹 · Dmitri Melikhov🇦🇹 · Hagop Sazdjian🇫🇷

    Two-ordinary-meson scattering in large-$N_c$ QCD implies consistency criteria for intermediate-tetraquark contributions. Their fulfilment at $N_c$-leading order constrains the nature of the spectrum of genuinely exotic tetraquark states.

    hep-phEPJ Web Conf.(2018)·8 citations
11. 11*

    Multi-Higgs Production and Unitarity in Vector-Boson Fusion at Future Hadron Colliders

    Wolfgang Kilian🇩🇪 · Sichun Sun🇨🇳 · Qi-Shu Yan🇨🇳 · Xiaoran Zhao🇧🇪 · Zhijie Zhao🇩🇪

    We study multi-Higgs final states in vector boson fusion (VBF) processes at the LHC and at future proton-proton colliders, focusing on the prospects for measurements at 27 TeV and at 100 TeV. We use an effective Lagrangian which includes higher-dimensional operators in the mass eigenstates which are relevant to VBF processes and relate this to specific parameterizations and models for new physics in the Higgs sector. We derive theoretical constraints on the parameter space from the unitarity of $2\to n$ scattering amplitudes and apply the results to $VV\to hh$ and $hhh$ processes, where $V=W,Z$. As a result, we present constraints on differential distributions as appropriate to the study of $VV\to hh$ and $hhh$ processes.

    hep-phPRD(2020)·39 citations
12. 12*

    Cosmic infrared background excess from axion-like particles and implications for multi-messenger observations of blazars

    Oleg E. Kalashev🇷🇺 · Alexander Kusenko🇺🇸 · Edoardo Vitagliano🇩🇪

    The first measurement of the diffuse background spectrum at 0.8-1.7 $\mu \mathrm{m}$ from the CIBER experiment has revealed a significant excess of the cosmic infrared background (CIB) radiation compared to the theoretically expected spectrum. We revisit the hypothesis that decays of axionlike particle (ALP) can explain this excess, extending previous analyses to the case of a warm relic population. We show that such a scenario is not excluded by anisotropy measurements nor by stellar cooling arguments. Moreover, we find that the increased extragalactic background light (EBL) does not contradict observations of blazar spectra. Furthermore, the increased EBL attenuates the diffuse TeV gamma-ray flux and alleviates the tension between the detected neutrino and gamma ray fluxes.

    hep-phastro-ph.COPRD(2019)·63 citations
13. 13*

    Theory overview of semileptonic $B$ decays

    Olcyr Sumensari🇮🇹

    I review the recent theoretical progress on the study of tree-level semileptonic $b\to c$ decays. After briefly reviewing the latest developments on the exclusive determinations of $|V_{cb}|$, I discuss the hints on lepton flavor universality violation in $B\to D^{(\ast )}\ell \bar{\nu }$ decays. Particular emphasis is given to the implications of these anomalies and to the possibilities to experimentally test the proposed New Physics explanations.

    hep-phPoS(2018)·0 citations
14. 14*

    Constraints on Spin-Dependent Dark Matter Scattering with Long-Lived Mediators from TeV Observations of the Sun with HAWC

    A. Albert · R. Alfaro · C. Alvarez · R. Arceo · J.C. Arteaga-Velázquez · D. Avila Rojas · H.A. Ayala Solares · E. Belmont-Moreno · S.Y. BenZvi · C. Brisbois · K.S. Caballero-Mora · T. Capistràn and 82 other authors

    We analyze the Sun as a source for the indirect detection of dark matter through a search for gamma rays from the solar disk. Capture of dark matter by elastic interactions with the solar nuclei followed by annihilation to long-lived mediators can produce a detectable gamma-ray flux. We search three years of data from the High Altitude Water Cherenkov Observatory and find no statistically significant detection of TeV gamma-ray emission from the Sun. Using this, we constrain the spin-dependent elastic scattering cross section of dark matter with protons for dark matter masses above 1 TeV, assuming an unstable mediator with a favorable lifetime. The results complement constraints obtained from Fermi-LAT observations of the Sun and together cover WIMP masses between 4 GeV and $10^6$ GeV. The cross section constraints for mediator decays to gamma rays can be as strong as $\sim 10^{-45}$ cm${}^{-2}$, which is more than four orders of magnitude stronger than current direct-detection experiments for 1 TeV dark matter mass. The cross-section constraints at higher masses are even better, nearly 7 orders of magnitude better than the current direct-detection constraints for 100 TeV dark matter mass. This demonstration of sensitivity encourages detailed development of theoretical models in light of these powerful new constraints.

    hep-phastro-ph.HEastro-ph.SRPRD(2018)·92 citations
15. 15*

    Hidden-Sector Modifications to Gravitational Waves From Binary Inspirals

    Stephon Alexander🇺🇸 · Evan McDonough🇺🇸 · Robert Sims🇺🇸 · Nicolas Yunes🇺🇸

    Gravitational wave astronomy has placed strong constraints on fundamental physics, and there is every expectation that future observations will continue to do so. In this work we quantify this expectation for future binary merger observations to constrain hidden sectors, such as scalar-tensor gravity or dark matter, which induce a Yukawa-type modification to the gravitational potential. We explicitly compute the gravitational waveform, and perform a Fisher information matrix analysis to estimate the sensitivity of next generation gravitational wave detectors to these modifications. We find an optimal sensitivity to the Yukawa interaction strength of $10^{-5}$ and to the associated dipole emission parameter of $10^{-7}$, with the best constraints arising from the Einstein Telescope. When applied to a minimal model of dark matter, this provides an exquisite probe of dark matter accumulation by neutron stars, and for sub-TeV dark matter gravitational waves are able to detect mass fractions $m_{DM}/m_{NS}$ less then 1 part in $10^{15}$.

    ↳ gr-qchep-phhep-thClass.Quant.Grav.(2018)·60 citations
16. 16*

    QCD Sum Rule for Open Strange Meson $K_1^{\pm }$ in Nuclear Matter

    Taesoo Song🇩🇪 · Tetsuo Hatsuda🇯🇵 · Su Houng Lee🇰🇷

    The properties of open strange meson $K_1^{\pm }$ in nuclear matter are estimated in the QCD sum rule approach. We obtain a relation between the in-medium mass and width of $K_1^{-}$ ($K_1^{+}$) in nuclear matter, and show that the upper limit of the mass shift is as large as -249 (-35) MeV. The spectral modification of the $K_1$ meson is possible to be probed by using kaon beams at J-PARC. Such measurement together with that of $K^{\ast }$ will shed light on how chiral symmetry is partially restored in nuclear matter.

    ↳ nucl-thhep-phPLB(2019)·26 citations
17. 17*

    Deuteron disintegration by reactor antineutrinos

    L.M. Slad🇷🇺

    The existence of a new interaction involving the electron neutrino and the nucleons, which has received a convincing confirmation through a good agreement between the theoretical and experimental results concerning all observable processes with solar neutrinos, should also inevitably manifest itself in the deuteron disintegration by reactor antineutrinos neutral currents. In this paper, the analytical and numerical characteristics of such a disintegration are presented. The attention is drawn to the problem of finding the neutron registration efficiency, discussed in the preparation of the experiment at the Sudbury Neutrino Observatory and in a number of special studies, to the role of quenching gas in proportional counters with helium-3 and to three performed reactor experiments with heavy water.

    ↳ nucl-thhep-phIJMPE(2021)·2 citations
18. 18*

    Using Gaia DR2 to Constrain Local Dark Matter Density and Thin Dark Disk

    Jatan Buch🇺🇸 · John Shing Chau Leung🇺🇸 · JiJi Fan🇺🇸

    We use stellar kinematics from the latest Gaia data release (DR2) to measure the local dark matter density ${\rho }_{\mathrm{DM}}$ in a heliocentric cylinder of radius $R=150\mathrm{pc}$ and half-height $z=200\mathrm{pc}$. We also explore the prospect of using our analysis to estimate the DM density in local substructure by setting constraints on the surface density and scale height of a thin dark disk aligned with the baryonic disk and formed due to dark matter self-interaction. Performing the statistical analysis within a Bayesian framework for three types of tracers, we obtain ${\rho }_{\mathrm{DM}}=0.016\pm 0.010$ M${}_{\odot }$/pc${}^3$ for A stars; early G stars give a similar result, while F stars yield a significantly higher value. For a thin dark disk, A stars set the strongest constraint: excluding surface densities (5-12) M${}_{\odot }$/pc${}^2$ for scale heights below 100 pc with 95% confidence. Comparing our results with those derived using Tycho-Gaia Astrometric Solution (TGAS) data, we find that the uncertainty in our measurements of the local DM content is dominated by systematic errors that arise from assumptions of our kinematic analysis in the low $z$ region. Furthermore, there will only be a marginal reduction in these uncertainties with more data in the Gaia era. We comment on the robustness of our method and discuss potential improvements for future work.

    ↳ astro-ph.GAhep-phJCAP(2019)·114 citations
19. 19*

    First HAWC Observations of the Sun Constrain Steady TeV Gamma-Ray Emission

    A. Albert · R. Alfaro · C. Alvarez · R. Arceo · J.C. Arteaga-Velázquez · D. Avila Rojas · H.A. Ayala Solares · E. Belmont-Moreno · S.Y. BenZvi · C. Brisbois · K.S. Caballero-Mora · T. Capistràn and 83 other authors

    Steady gamma-ray emission up to at least 200 GeV has been detected from the solar disk in the Fermi-LAT data, with the brightest, hardest emission occurring during solar minimum. The likely cause is hadronic cosmic rays undergoing collisions in the Sun's atmosphere after being redirected from ingoing to outgoing in magnetic fields, though the exact mechanism is not understood. An important new test of the gamma-ray production mechanism will follow from observations at higher energies. Only the High Altitude Water Cherenkov (HAWC) Observatory has the required sensitivity to effectively probe the Sun in the TeV range. Using three years of HAWC data from November 2014 to December 2017, just prior to the solar minimum, we search for 1--100 TeV gamma rays from the solar disk. No evidence of a signal is observed, and we set strong upper limits on the flux at a few $10^{-12}$ TeV${}^{-1}$ cm${}^{-2}$ s${}^{-1}$ at 1 TeV. Our limit, which is the most constraining result on TeV gamma rays from the Sun, is $\sim 10\%$ of the theoretical maximum flux (based on a model where all incoming cosmic rays produce outgoing photons), which in turn is comparable to the Fermi-LAT data near 100 GeV. The prospects for a first TeV detection of the Sun by HAWC are especially high during solar minimum, which began in early 2018.

    ↳ astro-ph.HEastro-ph.SRhep-phPRD(2018)·52 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.