HEP Phenomenology·hep-ph

Mon·Mar 27, 2017Monday·March 27, 2017

22 papers—16 primary·6 cross-listed·reconstructed*

01*
Electroweak Bubble Wall Speed Limit
Dietrich Bodeker🇩🇪 · Guy D. Moore🇩🇪
In extensions of the Standard Model with extra scalars, the electroweak phase transition can be very strong, and the bubble walls can be highly relativistic. We revisit our previous argument that electroweak bubble walls can "run away," that is, achieve extreme ultrarelativistic velocities $γ \sim 1 0^{14}$ . We show that, when particles cross the bubble wall, they can emit transition radiation. Wall-frame soft processes, though suppressed by a power of the coupling $α$ , have a significance enhanced by the $γ$ -factor of the wall, limiting wall velocities to $γ \sim 1/ α$ . Though the bubble walls can move at almost the speed of light, they carry an infinitesimal share of the plasma's energy.
hep-phastro-ph.COJCAP(2017)·365 citations
02*
On large lepton number asymmetries of the Universe
Gabriela Barenboim🇪🇸 · Wan-Il Park🇰🇷
A large lepton number asymmetry of $O (0.1 - 1)$ at present universe might not only be allowed but also necessary for consistency among cosmological data. We show that, if a sizeable lepton number asymmetry were produced before the electroweak phase transition, the requirement for not producing too much baryon number asymmetry through sphalerons processes, forces the high scale lepton number asymmetry to be larger than about $30$ . Therefore a mild entropy release causing $O (10 - 100)$ suppression of pre-existing particle density should take place, when the background temperature of the universe is around $T = O (1 0^{- 2} - 1 0^{2}) GeV$ for a large but experimentally consistent asymmetry to be present today. We also show that such a mild entropy production can be obtained by the late-time decays of the saxion, constraining the parameters of the Peccei-Quinn sector such as the mass and the vacuum expectation value of the saxion field to be $m_{ϕ} ≳ O (10) TeV$ and $ϕ_{0} ≳ O (1 0^{14}) GeV$ , respectively.
hep-phJCAP(2017)·23 citations
03*
Addressing $R_{K}$ and neutrino mixing in a class of $U (1)_{X}$ models
Disha Bhatia🇮🇳 · Sabyasachi Chakraborty🇮🇳 · Amol Dighe🇮🇳
We present a class of minimal $U (1)_{X}$ models as a plausible solution to the $R_{K}$ anomaly that can also help reproduce the neutrino mixing pattern. The symmetries and the corresponding $X$ -charges of the fields are determined in a bottom-up approach demanding both theoretical and experimental consistencies. The breaking of $U (1)_{X}$ symmetry results in a massive $Z^{'}$ , whose couplings with leptons and quarks are necessarily non-universal to address the $R_{K}$ anomaly. In the process, an additional Higgs doublet is introduced to generate quark mixings. The mixings in the neutrino sector are generated through Type-I seesaw mechanism by the addition of three right handed neutrinos and a scalar singlet. The $Z^{'}$ can be probed with a few hundred fb $^{- 1}$ of integrated luminosity at the 13 TeV LHC in the di-muon channel.
hep-phPoS(2017)·0 citations
04*
Quark transverse spin-orbit correlations
Amit Bhoonah (ETH Zürich)🇨🇦 · Cédric Lorcé (Ecole polytechnique, CPHT)🇫🇷
We extend the study of quark spin-orbit correlations in the nucleon to the case of transverse polarization. At the leading-twist level, this completes the spin structure of the quark kinetic energy-momentum tensor. In particular, we revisit the transversity decomposition of angular momentum proposed a decade ago by Burkardt and introduce a new transverse correlation, namely between quark transversity and orbital angular momentum. We also provide for the first time the Wandzura-Wilczek expression for the second Mellin moment of twist-3 transversity generalized parton distributions, along with a new sum rule. Based on lattice calculation results, we conclude that the quark transverse spin-orbit correlation is negative for both up and down flavors, just like in the longitudinal case.
hep-phnucl-thPLB(2017)·23 citations
05*
Two-loop Anomalous Dimensions for Four-Fermi Operators in Supersymmetric Theories
Junji Hisano🇯🇵 · Takumi Kuwahara🇯🇵 · Yuji Omura🇯🇵 · Takeki Sato🇯🇵
We derive two-loop anomalous dimensions for four-Fermi operators in supersymmetric theories using the effective Kahler potential. We introduce the general forms in generic gauge theories and apply our results to the flavor-changing operators in (minimal) supersymmetric standard models.
hep-phNPB(2017)·1 citation
06*
Holograms of a Dynamical Top Quark
Will Clemens🇬🇧 · Nick Evans🇬🇧 · Marc Scott🇬🇧
We present holographic desciptions of dynamical electroweak symmetry breaking models that incorporate the top mass generation mechanism. The models allow computation of the spectrum in the presence of large anomalous dimensions due to walking and strong NJL interactions. Technicolour and QCD dynamics are described by the bottom-up Dynamic AdS/QCD model for arbitrary gauge groups and numbers of quark flavours. An assumption about the running of the anomalous dimension of the quark bilinear operator is input and the model then predicts the spectrum and decay constants for the mesons. We add NJL interactions responsible for flavour physics from extended tecnhicolour, top-colour etc using Witten's multi-trace prescription. We show the key behaviours of a top condensation model can be reproduced. We study generation of the top mass in (walking) one doublet and one family technicolour models and with strong ETC interactions. The models clearly reveal the tensions between the large top mass and precision data for delta rho. The neccessary tunings needed to generate a model compatible with precision constraints are simply demonstrated.
hep-phPRD(2017)·7 citations
07*
The Dark Side of the Propagators: exploring their analytic properties by a massive expansion
Fabio Siringo🇮🇹
Analytical functions for the propagators of QCD, including a set of chiral quarks, are derived by a one-loop massive expansion in the Landau gauge, and are studied in Minkowski space, yielding a direct proof of positivity violation and confinement from first principles. Complex conjugated poles are found for the gluon propagator.
hep-phhep-thEPJ Web Conf.(2017)·3 citations
08*
Starobinsky-like inflation in no-scale supergravity Wess-Zumino model with Polonyi term
Miguel Crispim Romao🇬🇧 · Stephen F. King🇬🇧
We propose a simple modification of the no-scale supergravity Wess-Zumino model of Starobinsky-like inflation to include a Polonyi term in the superpotential. The purpose of this term is to provide an explicit mechanism for supersymmetry breaking at the end of inflation. We show how successful inflation can be achieved for a gravitino mass satisfying the strict upper bound $m_{3/2} < 1 0^{3}$ TeV, with favoured values $m_{3/2} ≲ O (1)$ TeV. The model suggests that SUSY may be discovered in collider physics experiments such as the LHC or the FCC.
hep-phastro-ph.COgr-qchep-thJHEP(2017)·34 citations
09*
Simulations of "Tunnelling of the 3rd Kind"
Zong-Gang Mou🇳🇴 · Paul M. Saffin🇬🇧 · Paul Tognarelli🇬🇧 · Anders Tranberg🇳🇴
We consider the phenomenon of "tunnelling of the 3rd kind", whereby a magnetic field may traverse a classically impenetrable barrier by pair creation of unimpeded quantum fermions. These propagate through the barrier and generate a magnetic field on the other side. We study this numerically using quantum fermions coupled to a classical Higgs-gauge system, where we set up a magnetic field outside a box shielded by two superconducting barriers. We examine the magnitude of the internal magnetic field, and find agreement with existing perturbative results within a factor of two.
hep-phJHEP(2017)·1 citation
10*
New factorization theory for heavy quarkonium production and decay
Yan-Qing Ma🇨🇳 · Kuang-Ta Chao🇨🇳
The widely used nonrelativistic QCD (NRQCD) factorization theory now encounters some notable difficulties in describing quarkonium production. This may be due to the inadequate treatment of soft hadrons emitted in the hadronization process, which causes bad convergence of velocity expansion in NRQCD. In this paper, starting from QCD we propose a rigorously defined factorization approach, soft gluon factorization (SGF), to better deal with the effects of soft hadrons. After a careful velocity expansion, the SGF can be as simple as the NRQCD factorization in phenomenological studies, but has a much better convergence. The SGF may provide a new insight to understand the mechanisms of quarkonium production and decay.
hep-phhep-exPRD(2019)·35 citations
11*
Light-by-Light Scattering Constraint on Born-Infeld Theory
John Ellis🇬🇧 · Nick E. Mavromatos🇬🇧 · Tevong You🇬🇧
The recent measurement by ATLAS of light-by-light scattering in LHC Pb-Pb collisions is the first direct evidence for this basic process. We find that it requires the mass scale of a nonlinear Born-Infeld extension of QED to be $≳ 100$ ~GeV, a much stronger constraint than those derived previously. In the case of a Born-Infeld extension of the Standard Model in which the U(1) $_{Y}$ hypercharge gauge symmetry is realized nonlinearly, the limit on the corresponding mass scale is $≳ 90$ ~GeV, which in turn imposes a lower limit of $≳ 11$ ~TeV on the magnetic monopole mass in such a U(1) $_{Y}$ Born-Infeld theory.
hep-phhep-exhep-thnucl-ex+1PRL(2017)·183 citations
12*
Spontaneous symmetry breaking in three-Higgs-doublet $S_{3}$ -symmetric models
D. Emmanuel-Costa🇵🇹 · O. M. Ogreid🇳🇴 · P. Osland🇳🇴 · M. N. Rebelo🇵🇹
The talk summarises work done by the authors consisting of a detailed study of the possible vacua in models with three Higgs doublets with $S_{3}$ symmetry and without explicit CP violation. Different vacua require special regions of the parameter space which were analysed in our work. We establish the possibility of spontaneous CP violation in this framework and we also show which complex vacua conserve CP. In our work we discussed constraints from vacuum stability. The results presented here are relevant for model building.
hep-phJ.Phys.Conf.Ser.(2017)·3 citations
13*
Azimuthal asymmetries in QCD hard scattering: infrared safe but divergent
S. Catani🇮🇹 · M. Grazzini🇨🇭 · H. Sargsyan🇨🇭
We consider high-mass systems of two or more particles that are produced by QCD hard scattering in hadronic collisions. We examine the azimuthal correlations between the system and one of its particles. We point out that the perturbative QCD computation of such azimuthal correlations and asymmetries can lead to divergent results at fixed perturbative orders. The fixed-order divergences affect basic (and infrared safe) quantities such as the total cross section at fixed (and arbitrary) values of the azimuthal-correlation angle $φ$ . Examples of processes with fixed-order divergences are heavy-quark pair production, associated production of vector bosons and jets, dijet and diboson production. A noticeable exception is the production of high-mass lepton pairs through the Drell--Yan mechanism of quark-antiquark annihilation. However, even in the Drell--Yan process, fixed-order divergences arise in the computation of QED radiative corrections. We specify general conditions that produce the divergences by discussing their physical origin in fixed-order computations. We show lowest-order illustrative results for $cos (n φ)$ asymmetries (with $n = 1, 2, 4, 6$ ) in top-quark pair production and associated production of a vector boson and a jet at the LHC. The divergences are removed by a proper all-order resummation procedure of the perturbative contributions. Resummation leads to azimuthal asymmetries that are finite and computable. We present first quantitative results of such a resummed computation for the $cos (2 φ)$ asymmetry in top-quark pair production at the LHC.
hep-phhep-exJHEP(2017)·39 citations
14*
Charged Higgs production from polarized top-quark decay in the 2HDM considering the general-mass variable-flavor-number scheme
S. Abbaspour🇮🇷 · S. Mohammad Moosavi Nejad🇮🇷
Charged Higgs bosons $H^{\pm}$ are predicted by some non-minimal Higgs scenarios, such as models containing Higgs triplets and two-Higgs-doublet models, so that the experimental observation of these bosons would indicate physics beyond the Standard Model. In the present work, we introduce a new channel to indirect search for the charged Higgses through the hadronic decay of polarized top quarks where a top quark decays into a charged Higgs $H^{+}$ and a bottom-flavored hadron $B$ via the hadronization process of the produced bottom quark, $t (↑) \to H^{+} + b (\to B + j e t)$ . To obtain the energy spectrum of produced $B$ -hadrons we present, for the first time, an analytical expression for the $O (α_{s})$ corrections to the differential decay width of the process $t \to H^{+} b$ in the presence of a massive b-quark in the General-Mass Variable-Flavor-Number Scheme (GM-VFNS). We find that the most reliable predictions for the B-hadron energy spectrum are made in the GM-VFN scheme, specifically, when the Type-II 2HDM scenario is concerned.
hep-phNPB(2018)·2 citations
15*
Four-loop QCD propagators and vertices with one vanishing external momentum
B. Ruijl (NIKHEF, Amsterdam & Leiden U.)🇳🇱 · T. Ueda🇳🇱 · J.A.M. Vermaseren (NIKHEF, Amsterdam)🇳🇱 · A. Vogt (Liverpool U., Dept. Math.)🇬🇧
We have computed the self-energies and a set of three-particle vertex functions for massless QCD at the four-loop level in the MSbar renormalization scheme. The vertex functions are evaluated at points where one of the momenta vanishes. Analytical results are obtained for a generic gauge group and with the full gauge dependence, which was made possible by extensive use of the Forcer program for massless four-loop propagator integrals. The bare results in dimensional regularization are provided in terms of master integrals and rational coefficients; the latter are exact in any space-time dimension. Our results can be used for further precision investigations of the perturbative behaviour of the theory in schemes other than MSbar. As an example, we derive the five-loop beta function in a relatively common alternative, the minimal momentum subtraction (MiniMOM) scheme.
hep-phJHEP(2017)·57 citations
16*
New Constraints on Dark Matter Production during Kination
Kayla Redmond🇺🇸 · Adrienne L. Erickcek🇺🇸
Our ignorance of the period between the end of inflation and the beginning of Big Bang Nucleosynthesis limits our understanding of the origins and evolution of dark matter. One possibility is that the Universe's energy density was dominated by a fast-rolling scalar field while the radiation bath was hot enough to thermally produce dark matter. We investigate the evolution of the dark matter density and derive analytic expressions for the dark matter relic abundance generated during such a period of kination. Kination scenarios in which dark matter does not reach thermal equilibrium require $⟨ σ v ⟩ < 2.7 \times 1 0^{- 38} c m^{3} s^{- 1}$ to generate the observed dark matter density while allowing the Universe to become radiation dominated by a temperature of $3 MeV$ . Kination scenarios in which dark matter does reach thermal equilibrium require $⟨ σ v ⟩ > 3 \times 1 0^{- 26} c m^{3} s^{- 1}$ in order to generate the observed dark matter abundance. We use observations of dwarf spheroidal galaxies by the Fermi Gamma-Ray Telescope and observations of the Galactic Center by the High Energy Stereoscopic System to constrain these kination scenarios. Combining the unitarity constraint on $⟨ σ v ⟩$ with these observational constraints sets a lower limit on the temperature at which the Universe can become radiation dominated following a period of kination if $⟨ σ v ⟩ > 3 \times 1 0^{- 31} c m^{3} s^{- 1}$ . This lower limit is between $0.05 GeV$ and $1 GeV$ , depending on the dark matter annihilation channel.
hep-phPRD(2017)·50 citations
17*
Universal horizons and Hawking radiation in nonprojectable 2d Hořava gravity coupled with a non-relativistic scalar field
Bao-Fei Li🇨🇳 · Madhurima Bhattacharjee🇺🇸 · Anzhong Wang🇨🇳
In this paper, we study the non-projectable 2d Hořava gravity coupled with a non-relativistic scalar field, where the coupling is in general non-minimal and of the form $f (ϕ) R$ , where $f (ϕ)$ is an arbitrary function of the scalar field $ϕ$ , and $R$ denotes the 2d Ricci scalar. In particular, we first investigate the Hamiltonian structure, and show that there are two-first and two-second class constraints, similar to the pure gravity case, but now the local degree of freedom is one, due to the presence of the scalar field. Then, we present various exact stationary solutions of this coupled system, and find that some of them represent black holes but now with universal horizons as their boundaries. At these horizons, the Hawking radiations are thermal with temperatures proportional to their surface gravities, which normally depend on the non-linear dispersion relations of the particles radiated, similar to the (3+1)-dimensional case.
↳ gr-qcastro-ph.HEhep-phhep-thPRD(2017)·4 citations
18*
Possible signals of vacuum dynamics in the Universe
Joan Sola Peracaula🇪🇸 · Javier de Cruz Perez🇪🇸 · Adria Gomez-Valent🇪🇸
We study a generic class of time-evolving vacuum models which can provide a better phenomenological account of the overall cosmological observations as compared to the $Λ$ CDM. Among these models, the running vacuum model (RVM) appears to be the most motivated and favored one, at a confidence level of $\sim 3 σ$ . We further support these results by computing the Akaike and Bayesian information criteria. Our analysis also shows that we can extract fair signals of dynamical dark energy (DDE) by confronting the same set of data to the generic XCDM and CPL parametrizations. In all cases we confirm that the combined triad of modern observations on Baryonic Acoustic Oscillations, Large Scale Structure formation, and the Cosmic Microwave Background, provide the bulk of the signal sustaining a possible vacuum dynamics. In the absence of any of these three crucial data sources, the DDE signal can not be perceived at a significant confidence level. Its possible existence could be a cure for some of the tensions existing in the $Λ$ CDM when confronted to observations.
↳ astro-ph.COgr-qchep-phhep-thMNRAS(2018)·197 citations
19*
Off-forward gluonic structure of vector mesons
W. Detmold🇺🇸 · D. Pefkou🇺🇸 · P. E. Shanahan🇺🇸
The spin-independent and transversity generalised form factors (GFFs) of the $ϕ$ meson are studied using lattice QCD calculations with light quark masses corresponding to a pion mass $m_{π} \sim 450 (5)$ MeV. One transversity and three spin-independent GFFs related to the lowest moments of leading-twist spin-independent and transversity gluon distributions are obtained at six non-zero values of the momentum transfer up to 1.2 GeV $^{2}$ . These quantities are compared with the analogous spin-independent quark GFFs and the electromagnetic form factors determined on the same lattice ensemble. The results show quantitative distinction between the spatial distribution of transversely polarised gluons, unpolarised gluons, and quarks, and point the way towards further investigations of the gluon structure of nucleons and nuclei.
↳ hep-lathep-phnucl-thPRD(2017)·17 citations
20*
Trans-Planckian quantum corrections and inflationary vacuum fluctuations of non-minimally coupled scalar fields
Hiroki Matsui🇯🇵
In the present paper we discuss how trans-Planckian physics affects inflationary vacuum fluctuations and primordial density perturbations. The trans-Planckian problem during inflation has been widely discussed in literature, but it is still under debate. We reconsider this problem by using the two-point correlation function of the non-minimally coupled scalar fields and constructing the effective potential with the adiabatic (WKB) regularization or approximation. First, we clearly show that the cut-off divergence of the quantum fluctuations does not drastically change during inflation under reasonable assumptions and the corrections can be embedded in standard effective potential. Thus, the UV effects on the primordial density perturbation are well translated into the effective potential. Then, we find out the modified effective potential from the inflationary fluctuations and show how the trans-Planckian or UV corrections change the potential during inflation. We clearly show that the new physics strongly affects the inflation potential during inflation and we obtain a inflationary constraint $Λ_{UV} ≪ H / g^{1/2}$ where $g$ is the interaction coupling at the UV scale $Λ_{UV}$ .
↳ hep-thgr-qchep-phMod.Phys.Lett.A(2019)·1 citation
21*
Search for sterile neutrinos in holographic dark energy cosmology: Reconciling Planck observation with the local measurement of the Hubble constant
Ming-Ming Zhao🇨🇳 · Dong-Ze He🇨🇳 · Jing-Fei Zhang🇨🇳 · Xin Zhang🇨🇳
We search for sterile neutrinos in the holographic dark energy cosmology by using the latest observational data. To perform the analysis, we employ the current cosmological observations, including the cosmic microwave background temperature power spectrum data from the Planck mission, the baryon acoustic oscillation measurements, the type Ia supernova data, the redshift space distortion measurements, the shear data of weak lensing observation, the Planck lensing measurement, and the latest direct measurement of $H_{0}$ as well. We show that, compared to the $Λ$ CDM cosmology, the holographic dark energy cosmology with sterile neutrinos can relieve the tension between the Planck observation and the direct measurement of $H_{0}$ much better. Once we include the $H_{0}$ measurement in the global fit, we find that the hint of the existence of sterile neutrinos in the holographic dark energy cosmology can be given. Under the constraint of the all-data combination, we obtain $N_{eff} = 3.76 \pm 0.26$ and $m_{ν, sterile}^{eff} < 0.215 eV$ , indicating that the detection of $Δ N_{eff} > 0$ in the holographic dark energy cosmology is at the $2.75 σ$ level and the massless or very light sterile neutrino is favored by the current observations.
↳ astro-ph.COgr-qchep-phhep-thPRD(2017)·108 citations
22*
The $_{ΛΛ}^{4} n$ system
H. Garcilazo🇲🇽 · A. Valcarce🇪🇸 · J. Vijande🇪🇸
Using local central Yukawa-type Malfliet-Tjon interactions reproducing the low-energy parameters and phase shifs of the $nn$ system and the latest updates of the $n Λ$ and $ΛΛ$ Nijmegen ESC08c potentials we study the possible existence of a $_{ΛΛ}^{4} n$ bound state. Our results indicate that the $_{ΛΛ}^{4} n$ is unbound, being just above threshold. We discuss the role played by the $^{1} S_{0}$ $nn$ repulsive term of the Yukawa-type Malfliet-Tjon interaction.
↳ nucl-thhep-phCPC(2017)·9 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.