Mon·Dec 7, 2015Monday·December 7, 2015

1. 01*

   Implications of the top (and Higgs) mass for vacuum stability

   Jose R. Espinosa🇪🇸

   The discovery of the Higgs boson by the LHC and the measurement of its mass at around 125 GeV, taken together with the absence of signals of physics beyond the standard model, make it possible that we might live in a metastable electroweak vacuum. Intriguingly, we seem to be very close to the boundary of stability and this near-criticality makes our vacuum extremely long-lived. In this talk I describe the state-of-the-art calculation leading to these results, explaining what are the ingredients and assumptions that enter in it, with special emphasis on the role of the top mass. I also discuss possible implications of this metastability for physics beyond the standard model and comment on the possible impact of physics at the Planck scale on near-criticality.

   hep-phPoS(2016)·39 citations
2. 02*

   Automatic predictions in the Georgi-Machacek model at next-to-leading order accuracy

   Celine Degrande🇬🇧 · Katy Hartling🇨🇦 · Heather E. Logan🇨🇦 · Andrea D. Peterson🇨🇦 · Marco Zaro🇫🇷

   We study the phenomenology of the Georgi-Machacek model at next-to-leading order (NLO) in QCD matched to parton shower, using a fully-automated tool chain based on MadGraph5_aMC@NLO and FeynRules. We focus on the production of the fermiophobic custodial fiveplet scalars H_5^0, H_5^+/-, and H_5^++/-- through vector boson fusion (VBF), associated production with a vector boson (V H_5), and scalar pair production (H_5 H_5). For these production mechanisms we compute NLO corrections to production rates as well as to differential distributions. Our results demonstrate that the Standard Model (SM) overall K-factors for such processes cannot in general be directly applied to beyond-the-SM distributions, due both to differences in the scalar electroweak charges and to variation of the K-factors over the differential distributions.

   hep-phhep-exPRD(2016)·54 citations
3. 03*

   Heavy-Flavor-Conserving Hadronic Weak Decays of Heavy Baryons

   Hai-Yang Cheng🇹🇼 · Chi-Yee Cheung🇹🇼 · Guey-Lin Lin🇹🇼 · Yeu-Chung Lin🇹🇼 · Tung-Mow Yan🇺🇸 · Hoi-Lai Yu🇹🇼

   More than two decades ago, we studied heavy-flavor-conserving weak decays of heavy baryons within the framework that incorporates both heavy-quark and chiral symmetries. In view of the first observation of ${\Xi }_b^{-}\to {\Lambda }_b^0{\pi }^{-}$ by LHCb recently, we have reexamined these decays and presented updated predictions. The predicted rates for ${\Xi }_b^{-}\to {\Lambda }_b^0{\pi }^{-}$ in the MIT bag and diquark models are consistent with experiment. The major theoretical uncertainty stems from the evaluation of baryon matrix elements. The branching fraction of ${\Xi }_c\to {\Lambda }_c\pi$ is predicted to be of order $10^{-4}$. It is suppressed relative to $Br({\Xi }_b\to {\Lambda }_b\pi )$ owing to the shorter lifetime of ${\Xi }_c$ relative to ${\Xi }_b$ and the destructive nonspectator $W$-exchange contribution. The kinematically accessible weak decays of the sextet heavy baryon ${\Omega }_Q$ are ${\Omega }_Q\to {\Xi }_Q\pi$. Due to the absence of the $B_6-B_{\bar{3}}$ transition in the heavy quark limit and the $B_6-B_6$ transition in the model calculations, ${\Omega }_Q\to {\Xi }_Q\pi$ vanish in the heavy quark limit.

   hep-phhep-exJHEP(2016)·25 citations
4. 04*

   Z-boson production in association with a jet at next-to-next-to-leading order in perturbative QCD

   Radja Boughezal🇺🇸 · John M. Campbell🇺🇸 · R. Keith Ellis🇬🇧 · Christfried Focke🇺🇸 · Walter T. Giele🇺🇸 · Xiaohui Liu🇺🇸 · Frank Petriello🇺🇸

   We present the first complete calculation of Z-boson production in association with a jet in hadronic collisions through next-to-next-to-leading order in perturbative QCD. Our computation uses the recently-proposed N-jettiness subtraction scheme to regulate the infrared divergences that appear in the real-emission contributions. We present phenomenological results for 13 TeV proton-proton collisions with fully realistic fiducial cuts on the final-state particles. The remaining theoretical uncertainties after the inclusion of our calculations are at the percent-level, making the Z+jet channel ready for precision studies at the LHC Run II.

   hep-phhep-exPRL(2016)·235 citations
5. 05*

   Spin Polarized Photons from Axially Charged Plasma at Weak Coupling: Complete Leading Order

   Kiminad A. Mamo🇺🇸 · Ho-Ung Yee🇺🇸

   In the presence of (approximately conserved) axial charge in the QCD plasma at finite temperature, the emitted photons are spin-aligned, which is a unique P- and CP-odd signature of axial charge in the photon emission observables. We compute this "P-odd photon emission rate" in weak coupling regime at high temperature limit to complete leading order in the QCD coupling constant: the leading log as well as the constant under the log. As in the P-even total emission rate in the literature, the computation of P-odd emission rate at leading order consists of three parts: 1) Compton and Pair Annihilation processes with hard momentum exchange, 2) soft t- and u-channel contributions with Hard Thermal Loop re-summation, 3) Landau-Pomeranchuk-Migdal (LPM) re-summation of collinear Bremstrahlung and Pair Annihilation. We present analytical and numerical evaluations of these contributions to our P-odd photon emission rate observable.

   hep-phhep-thnucl-exnucl-thPRD(2016)·13 citations
6. 06*

   $B_c$ Production in Higgs Boson Decays

   Jun Jiang🇨🇳 · Cong-Feng Qiao🇨🇳

   $B_c$ production rate in Higgs boson decays is evaluated in NRQCD framework. Given Higgs total decay width is about $4.20MeV$ and the vector $B_c^{\ast }$ meson decays completely to the ground state, we find that the branching fraction of $B_c$ meson production in Higgs decays is $8.50\times 10^{-4}$, where both leading QED and QCD contributions are included. This process is hence detectable in the high-luminosity/energy LHC. In confronting to the quarkonia production, we find that the fraction rate of $B_c$ production is more than an order of magnitude bigger than those of charmonium and bottomoium production in Higgs decays. In the calculation, various differential distributions and uncertainties of the concerned processes are analysed.

   hep-phPRD(2016)·27 citations
7. 07*

   Introduction to GPDs and TMDs

   Markus Diehl🇩🇪

   Generalised parton distributions (GPDs) and transverse momentum dependent parton distributions (TMDs) describe complementary aspects of the three-dimensional structure of hadrons. We discuss their relation to each other and recall important theory results concerning their properties and their connection with physical observables.

   hep-phEPJA(2016)·142 citations
8. 08*

   Spin-dependent fragmentation functions of Gluon splitting into heavy quarkonia considering three different scenarios

   S. Mohammad Moosavi Nejad🇮🇷 · Mahdi Delpasand🇮🇷

   Heavy quarkonium production is a powerful implement to study the strong interaction dynamics and QCD theory. Fragmentation is the dominant production mechanism for heavy quarkonia with large transverse momentum. With the large heavy quark mass, the relative motion of the heavy quark pair inside a heavy quarkonium is effectively nonrelativistic and it is also well-known that their fragmentation functions can be calculated in the perturbative QCD framework. Here, we analytically calculate the process-independent fragmentation functions for a gluon to split into the spin-singlet and -triplet $S$-wave heavy quarkonia using three different scenarios. We will show that the fragmentation probability of the gluon into the spin-triplet bound-state is the biggest one.

   hep-phInt.J.Mod.Phys.A(2015)·23 citations
9. 09*

   Tests for Sivers, Boer-Mulders and transversity distributions in difference cross sections in SIDIS

   Ekaterina Christova🇧🇬 · Elliot Leader🇬🇧

   A major experimental program is presently underway to determine the Sivers, Boer-Mulders and transversity distributions, vital for understanding the internal structure of the nucleon. To this end we consider the Sivers, Boer-Mulders and transversity azimuthal asymmetries of the difference cross sections of hadrons with opposite charges in SIDIS reactions with unpolarized and transversely polarized target l+N\to l'+h+X, h=\pi^\pm, K^\pm, h^\pm. We show that on deuteron target these asymmetries are particularly simple and determine the sum of the valence-quark Q_V=u_V+d_V transverse momentum dependent distributions without any contributions from the strange or other sea-quark functions. At present, data on these asymmetries are presented for the integrated asymmetries i.e. the x_B- and z_h-dependent asymmetries. If data are available in small bins in Q^2, so that Q^2-dependence can be neglected, these expressions simplify dramatically leading to remarkably simple and powerful tests of the simplifying assumptions used in extracting these functions from the data.

   hep-phJ.Phys.Conf.Ser.(2016)·2 citations
10. 10*

    A search for neutrino signal from dark matter annihilation in the center of the Milky Way with Baikal NT200

    A.D. Avrorin🇷🇺 · A.V. Avrorin🇷🇺 · V.M. Aynutdinov🇷🇺 · R. Bannasch🇩🇪 · I.A. Belolaptikov🇷🇺 · D.Yu. Bogorodsky🇷🇺 · V.B. Brudanin🇷🇺 · N.M. Budnev🇷🇺 · I.A. Danilchenko🇷🇺 · S.V. Demidov🇷🇺 · G.V. Domogatsky🇷🇺 · A.A. Doroshenko🇷🇺 and 38 other authors

    We reanalyze the dataset collected during the years 1998--2003 by the deep underwater neutrino telescope NT200 in the lake Baikal with the low energy threshold (10 GeV) in searches for neutrino signal from dark matter annihilations near the center of the Milky Way. Two different approaches are used in the present analysis: counting events in the cones around the direction towards the Galactic Center and the maximum likelihood method. We assume that the dark matter particles annihilate dominantly over one of the annihilation channels $b\bar{b}$, $W^{+}{W}^{-}$, ${\tau }^{+}{\tau }^{-}$, ${\mu }^{+}{\mu }^{-}$ or $\nu \bar{\nu }$. No significant excess of events towards the Galactic Center over expected neutrino background of atmospheric origin is found and we derive 90% CL upper limits on the annihilation cross section of dark matter.

    ↳ astro-ph.HEhep-phAstropart.Phys.(2016)·15 citations
11. 11*

    A brief history of the multiverse

    Andrei Linde🇺🇸

    The theory of the inflationary multiverse changes the way we think about our place in the world. According to its most popular version, our world may consist of infinitely many exponentially large parts, exhibiting different sets of low-energy laws of physics. Since these parts are extremely large, the interior of each of them behaves as if it were a separate universe, practically unaffected by the rest of the world. This picture, combined with the theory of eternal inflation and anthropic considerations, may help to solve many difficult problems of modern physics, including the cosmological constant problem. In this article I will briefly describe this theory and provide links to the some hard to find papers written during the first few years of the development of the inflationary multiverse scenario.

    ↳ hep-thastro-ph.COgr-qchep-ph+1Rept.Prog.Phys.(2017)·95 citations
12. 12*

    Double Soft Theorems and Shift Symmetry in Nonlinear Sigma Models

    Ian Low🇺🇸

    We show both the leading and subleading double soft theorems of the nonlinear sigma model follow from a shift symmetry enforcing Adler's zero condition in the presence of an unbroken global symmetry. They do not depend on the underlying coset G/H and are universal infrared behaviors of Nambu-Goldstone bosons. Although nonlinear sigma models contain an infinite number of interaction vertices, the double soft limit is determined entirely by a single four-point interaction, together with the existence of Adler's zeros.

    ↳ hep-thhep-phPRD(2016)·60 citations
13. 13*

    Binary pulsars as dark-matter probes

    Paolo Pani🇮🇹

    During the motion of a binary pulsar around the Galactic center, the pulsar and its companion experience a wind of dark-matter particles that can affect the orbital motion through dynamical friction. We show that this effect produces a characteristic seasonal modulation of the orbit and causes a secular change of the orbital period whose magnitude can be well within the astonishing precision of various binary-pulsar observations. Our analysis is valid for binary systems with orbital period longer than a day. By comparing this effect with pulsar-timing measurements, it is possible to derive model-independent upper bounds on the dark-matter density at different distances $D$ from the Galactic center. For example, the precision timing of J1713+0747 imposes ${\rho }_{\mathrm{DM}}\lesssim 10^5{GeV/cm}^3$ at $D\approx 7\mathrm{kpc}$. The detection of a binary pulsar at $D\lesssim 10\mathrm{pc}$ could provide stringent constraints on dark-matter halo profiles and on growth models of the central black hole. The Square Kilometer Array can improve current bounds by 2 orders of magnitude, potentially constraining the local density of dark matter to unprecedented levels.

    ↳ astro-ph.HEgr-qchep-phPRD(2015)·38 citations
14. 14*

    Quantum mechanics of 4-derivative theories

    Alberto Salvio🇪🇸 · Alessandro Strumia🇨🇭

    A renormalizable theory of gravity is obtained if the dimension-less 4-derivative kinetic term of the graviton, which classically suffers from negative unbounded energy, admits a sensible quantisation. We find that a 4-derivative degree of freedom involves a canonical coordinate with unusual time-inversion parity, and that a correspondingly unusual representation must be employed for the relative quantum operator. The resulting theory has positive energy eigenvalues, normalisable wave functions, unitary evolution in a negative-norm configuration space. We present a formalism for quantum mechanics with a generic norm.

    ↳ hep-thgr-qchep-phEPJC(2016)·116 citations
15. 15*

    Deep XMM Observations of Draco rule out at the 99% Confidence Level a Dark Matter Decay Origin for the 3.5 keV Line

    Tesla E. Jeltema🇺🇸 · Stefano Profumo🇺🇸

    We searched for an X-ray line at energies around 3.5 keV in deep, ~1.6 Msec XMM-Newton observations of the dwarf spheroidal galaxy Draco. No line was found in either the MOS or the PN detectors. The data in this energy range are completely consistent with a single, unfolded power law modeling the particle background, which dominates at these energies, plus instrumental lines; the addition of a ~3.5 keV line feature gives no improvement to the fit. The corresponding upper limit on the line flux rules out a dark matter decay origin for the 3.5 keV line found in observations of clusters of galaxies and in the Galactic Center at greater than 99% C.L..

    ↳ astro-ph.HEastro-ph.COastro-ph.GAhep-phMNRAS(2016)·109 citations
16. 16*

    Sensitivity of the CUORE detector to $14.4$ keV solar axions emitted by the M1 nuclear transition of${}^{57}$Fe

    Dawei Li🇺🇸 · Richard J. Creswick🇺🇸 · Frank T. Avignone III🇺🇸 · Yuanxu Wang🇨🇳

    In this paper we present a calculation of the sensitivity of the CUORE detector to the monoenergetic $14.4$ keV solar axions emitted by the M1 nuclear transition of${}^{57}$Fe in the Sun and detected by inverse coherent Bragg-Primakoff conversion in single-crystal $Te{O}_2$ bolometers. The expected counting rate is calculated using density functional theory for the electron charge density of $Te{O}_2$ and realistic background and energy resolution of CUORE. Monte Carlo simulations for $5$ y $\times$ $741$ kg=$3705-$kg$\cdot$y of exposure are analyzed using time correlation of individual events with the theoretical time-dependent counting rate. We find an expected model-independent limit on the product of the axion-photon coupling and the axion-nucleon coupling $g_{a\gamma \gamma }{g}_{aN}^{\text{eff}}<1.105\times 10^{-16}$ /GeV for axion masses less than 500 eV with $95\%$ confidence level.

    ↳ astro-ph.COhep-phJCAP(2016)·16 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.