HEP Phenomenology·hep-ph

Tue·Jan 31, 2017Tuesday·January 31, 2017

37 papers—24 primary·13 cross-listed·reconstructed*

01*
Comment on "Single-inclusive jet production in electron-nucleon collisions through next-to-next-to-leading order in perturbative QCD" [Phys. Lett. B 763, 52--59 (2016)]
Geoffrey T. Bodwin🇺🇸 · Eric Braaten🇺🇸
In the cross section for single-inclusive jet production in electron-nucleon collisions, the distribution of a quark in an electron appears at next-to-next-to-leading order. The numerical calculations in Ref. [1] were carried out using a perturbative approximation for the distribution of a quark in an electron. We point out that that distribution receives nonperturbative QCD contributions that invalidate the perturbative approximation. Those nonperturbative effects enter into cross sections for hard-scattering processes through resolved-electron contributions and can be taken into account by determining the distribution of a quark in an electron phenomenologically.
hep-phPLB(2017)·1 citation
02*
Novel All-Orders Single-Scale Approach to QCD Renormalization Scale-Setting
Jian-Ming Shen🇨🇳 · Xing-Gang Wu🇨🇳 · Bo-Lun Du🇨🇳 · Stanley J. Brodsky🇺🇸
The Principle of Maximal Conformality (PMC) provides a rigorous method for eliminating renormalization scheme-and-scale ambiguities for perturbative QCD predictions. The PMC uses the renormalization group equation to fix the $β$ -pattern of each order in an arbitrary pQCD approximant, and it then determines the optimal renormalization scale by absorbing all ${β_{i}}$ terms into the running coupling at each order. The resulting coefficients of the pQCD series match the scheme-independent conformal series with $β = 0$ . As in QED, different renormalization scales appear at each order; we call this the multi-scale approach. In this paper, we present a novel single-scale approach for the PMC, in which a single effective scale is constructed to eliminate all non-conformal $β$ -terms up to a given order simultaneously. The PMC single-scale approach inherits the main features of the multi-scale approach; for example, its predictions are scheme-independent, and the pQCD convergence is greatly improved due to the elimination of divergent renormalon terms. As an application of the single-scale approach, we investigate the $e^{+} e^{-}$ annihilation cross-section ratio $R_{e^{+} e^{-}}$ and the Higgs decay-width $Γ (H \to b b ˉ)$ , including four-loop QCD contributions. The resulting predictions are nearly identical to the multi-scale predictions for both the total and differential contributions. Thus in many cases, the PMC single-scale approach PMC-s, which requires a simpler analysis, could be adopted as a reliable substitution for the PMC multi-scale approach for setting the renormalization scale for high-energy processes, particularly when one does not need detailed information at each order. The elimination of the renormalization scale uncertainty increases the precision of tests of the Standard Model at the LHC.
hep-phPRD(2017)·59 citations
03*
Constraining capability of $Z γ h$ production at the ILC
Sher Alam🇵🇰 · Subhasish Behera🇮🇳 · Satendra Kumar🇮🇳 · Shibananda Sahoo🇮🇳
Higgs boson couplings with gauge bosons are probed through $e^{-} e^{+} \to Z γ h$ in an effective Lagrangian framework. For this study the beam polarization facility at the ILC along with the typical center-of-mass energy of 500 GeV is considered. The reach of the ILC with an integrated luminosity of 300 fb $^{- 1}$ in the determination of $C P$ -conserving parameters is obtained. Sensitivity of the probe of each of these couplings in the presence of other couplings is investigated. The most influential coupling parameters are $c ˉ_{W} = - c ˉ_{B}$ . Other parameters of significant effect are $c ˉ_{H W}$ and $c ˉ_{H B}$ . A detailed study of the various kinematic distributions represents possibilities to disentangle the effect of some of these couplings.
hep-phInt.J.Mod.Phys.A(2017)·6 citations
04*
A direct extraction of the Sivers distributions from spin asymmetries in pion and kaon leptoproduction
Anna Martin🇮🇹 · Franco Bradamante🇮🇹 · Vincenzo Barone🇮🇹
We present a point-by-point determination of the Sivers distributions from hadron leptoproduction data. The method, which relies on some simple assumptions, is based on the combined analysis of proton and deuteron observables. We make use of the single-spin asymmetries measured by COMPASS in semi-inclusive deep inelastic scattering of 160 GeV muons on transversely polarized proton and deuteron targets.
hep-phPRD(2017)·30 citations
05*
Leptoquark mechanism of neutrino masses within the grand unification framework
Ilja Doršner🇭🇷 · Svjetlana Fajfer🇸🇮 · Nejc Košnik🇸🇮
We demonstrate viability of the one-loop neutrino mass mechanism within the framework of grand unification when the loop particles comprise scalar leptoquarks (LQs) and quarks of the matching electric charge. This mechanism can be implemented in both supersymmetric and non-supersymmetric models and requires the presence of at least one LQ pair. The appropriate pairs for the neutrino mass generation via the up-type and down-type quark loops are $S_{3}$ - $R_{2}$ and $S_{1, 3}$ - $R ~_{2}$ , respectively. We consider two phenomenologically distinct regimes for the LQ masses in our analysis. First regime calls for very heavy LQs in the loop. It can be naturally realised with the $S_{1, 3}$ - $R ~_{2}$ scenarios when the LQ masses are roughly between $1 0^{12}$ GeV and $5 \times 1 0^{13}$ GeV. These lower and upper bounds originate from experimental limits on partial proton decay lifetimes and perturbativity constraints, respectively. Second regime corresponds to the collider accessible LQs in the neutrino mass loop. That option is viable for the $S_{3}$ - $R ~_{2}$ scenario in the models of unification that we discuss. If one furthermore assumes the presence of the type II see-saw mechanism there is an additional contribution from the $S_{3}$ - $R_{2}$ scenario that needs to be taken into account beside the type II see-saw contribution itself. We provide a complete list of renormalizable operators that yield necessary mixing of all aforementioned LQ pairs using the language of $S U (5)$ . We furthermore discuss several possible embeddings of this mechanism in $S U (5)$ and $S O (10)$ gauge groups.
hep-phEPJC(2017)·95 citations
06*
Combined analysis of jet substructure for Higgs decay to $b b ˉ$ in vector boson associated production at the 13 TeV LHC
Fang Tian🇨🇳
We study the Standard Model Higgs and vector boson associated production with large transvese momentum at the 13 TeV LHC, followed by Higgs decay to bottom quark pair. Using mass-drop tagging and filtering techiques, we obtained the cross section of signal and background. The background mainly come from $V b b ˉ$ , $t t ˉ$ and single top production. In order to suppress them further, we combined the mass-drop tagging and filtering analysis with $N$ -subjettiness jet shape. After performing $N$ -subjettiness identification, the significance can be enhanced to 3.52 $σ$ with current integrated luminosity of $13.2 fb^{- 1}$ . $H \to b b ˉ$ decay channel is expected to reach 5 $σ$ with $27 fb^{- 1}$ at the 13 TeV LHC.
hep-ph3 citations
07*
$D$ - meson production at very forward rapidities: estimating the intrinsic charm contribution
F. Carvalho🇧🇷 · A.V. Giannini🇧🇷 · V.P. Goncalves🇧🇷 · F.S. Navarra🇧🇷
We study $D$ - meson production at forward rapidities taking into account the non - linear effects in the QCD dynamics and the intrinsic charm component of the proton wave function. The total cross section, the rapidity distributions and the Feynman - $x$ distributions are calculated for $pp$ collisions at different center of mass energies. Our results show that, at the LHC, the intrinsic charm component changes the $D$ rapidity distributions in a region which is beyond the coverage of the LHCb detectors. At higher energies the IC component dominates the $y$ and $x_{F}$ distributions exactly in the range where the produced $D$ mesons decay and contribute the most to the prompt atmospheric neutrino flux measured by the ICECUBE Collaboration. We compute the $x_{F}$ - distributions and demonstrate that they are enhanced at LHC energies by approximately one order of magnitude in the $0.2 \leq x_{F} \leq 0.8$ range.
hep-phhep-exnucl-exnucl-thPRD(2017)·20 citations
08*
First Results with HIJING++ in High-Energy Heavy-Ion Collisions
Gergely Gábor Barnaföldi🇭🇺 · Gábor Bíró🇭🇺 · Miklos Gyulassy🇺🇸 · Szilveszter Miklós Haranozó🇭🇺 · Péter Lévai🇭🇺 · Guoyang Ma🇨🇳 · Gábor Papp🇭🇺 · Xin-Nian Wang🇨🇳 · Ben-Wei Zhang🇨🇳
First calculated results with the new HIJING++ are presented for identified hadron production in high-energy heavy ion collisions. The recently developed HIJING++ version is based on the latest version of PYTHIA8 and contains all the nuclear effects has been included in the HIJING2.552, which will be improved by a new version of the shadowing parametrization and jet quenching module. Here, we summarize the major changes of the new program code beside the comparison between experimental data for some specific high-energy nucleus-nucleus collisions.
hep-phnucl-thNucl.Part.Phys.Proc.(2017)·12 citations
09*
Implications of residual CP symmetry for leptogenesis in a model with two right-handed neutrinos
Cai-Chang Li🇨🇳 · Gui-Jun Ding🇨🇳
We analyze the interplay between leptogenesis and residual symmetry in the framework of two right-handed neutrino model. Working in the flavor basis, we show that all the leptogenesis CP asymmetries are vanishing for the case of two residual CP transformations or a cyclic residual flavor symmetry in the neutrino sector. If a single remnant CP transformation is preserved in the neutrino sector, the lepton mixing matrix is determined up to a real orthogonal matrix multiplied from the right side. The $R$ -matrix is found to depend on only one real parameter, it can take three viable forms, and each entry is either real or purely imaginary. The baryon asymmetry is generated entirely by the CP violating phases in the mixing matrix in this scenario. We perform a comprehensive study for the $Δ (6 n^{2})$ flavor group and CP symmetry which are broken to a single remnant CP transformation in the neutrino sector and an abelian subgroup in the charged lepton sector. The results for lepton flavor mixing and leptogenesis are presented.
hep-phPRD(2017)·35 citations
10*
Recursive Monte Carlo code for transversely polarized quark jet
A. Kerbizi🇮🇹 · X. Artru🇫🇷 · Z. Belghobsi🇩🇿 · F. Bradamante🇮🇹 · A. Martin🇮🇹 · E. Redouane Salah🇩🇿
We propose a Monte Carlo code for the simulation of the fragmentation process of polarized quarks into pseudoscalar mesons. Such process is generated recursively once the flavour, the energy and the spin density matrix of the initial quark are specified, performing a cascade of splittings of the type $q \to h + q^{'}$ , where $q, q^{'}$ indicate quarks and $h$ the hadron with flavour content $q q ˉ^{'}$ . Each splitting is generated using a splitting distribution which has been calculated in a string fragmentation framework including, for the first time, the $^{3} P_{0}$ mechanism. This mechanism involves a "complex mass" parameter responsible for transverse spin effects, such as the Collins effect. Results for single hadron and hadron pair analyzing power are found to be in agreement with experimental results from SIDIS and $e^{+} e^{-}$ annihilation.
hep-ph6 citations
11*
Quark Wigner distributions and spin-spin correlations
D. Chakrabarti🇮🇳 · T. Maji🇮🇳 · C. Mondal🇮🇳 · A. Mukherjee🇮🇳
We investigate the Wigner distributions for $u$ and $d$ quarks in a light-front quark-diquark model of a proton to unravel the spatial and spin structure. The light-front wave functions are modeled from the soft-wall AdS/QCD prediction. We consider the contributions from both the scalar and the axial vector diquarks. The Wigner distributions for unpolarized, longitudinally polarized, and transversely polarized protons are presented in the transverse momentum plane as well as in the transverse impact parameter plane. The Wigner distributions satisfy a Soffer-bound-type inequality. We also evaluate all the leading twist GTMDs and show their scale evolution. The spin-spin correlations between the quark and the proton are investigated
hep-phPRD(2017)·49 citations
12*
The photon PDF from high-mass Drell Yan data at the LHC
F. Giuli🇬🇧 · xFitter Developers' team: V. Bertone🇳🇱 · D. Britzger🇩🇪 · S. Carrazza🇨🇭 · A. Cooper-Sarkar🇬🇧 · A. Glazov🇩🇪 · K. Lohwasser🇩🇪 · A. Luszczak🇵🇱 · F. Olness🇺🇸 · R. Placakyte🇩🇪 · V. Radescu🇩🇪 · J. Rojo🇳🇱 and 4 other authors
Achieving the highest precision for theoretical predictions at the LHC requires the calculation of hard-scattering cross-sections that include perturbative QCD corrections up to (N)NNLO and electroweak (EW) corrections up to NLO. Parton distribution functions (PDFs) need to be provided with matching accuracy, which in the case of QED effects involves introducing the photon parton distribution of the proton, $x γ (x, Q^{2})$ . In this work a determination of the photon PDF from fits to recent ATLAS measurements of high-mass Drell-Yan dilepton production at $s = 8$ TeV is presented. This analysis is based on the xFitter framework, and has required improvements both in the APFEL program, to account for NLO QED effects, and in the aMCfast interface to account for the photon-initiated contributions in the EW calculations within MadGraph5_aMC@NLO. The results are compared with other recent QED fits and determinations of the photon PDF, consistent results are found.
hep-phEPJC(2017)·46 citations
13*
Inelastic cross sections, overlap functions and Cq moments from ISR to LHC energies in proton interactions
P.C. Beggio🇧🇷
We investigated the energy dependence of the parton-parton inelastic cross sections, parton- parton inelastic overlap functions and the Cq moments in proton interactions from 10 to 14000 GeV. The used approach is based on a phenomenological procedure where elastic and inelastic proton observables are described in a connected way by exploring the unitarity of S- Matrix. Applying a Quantum Chromodynamics inspired eikonal model, that contains contributions of the quark-quark, quark-gluon and gluon-gluon interactions, theoretical predictions on inelastic cross sections and Cq moments are compared with measurements showing successfully description of the experimental data. The KNO hypothesis violation is discussed as a consequence of the semihard contribution to the multiparticle production in the interactions, in accordance to several experimental and theoretical previous results. Prediction to the ratio elastic to total cross sections as a function of the collision energy is presented and also compared with the experimental information.
hep-phJ.Phys.G(2017)·4 citations
14*
\large\bf $B_{c} \to (J /Ψ, η_{c}) τ ν$ semileptonic decays within Standard model and beyond
Rupak Dutta🇮🇳 · Anupama Bhol🇮🇳
Deviations from the standard model prediction have been observed not only in $b \to c$ charged current interactions but also in $b \to s$ flavor changing neutral current interactions. In particular, the deviation observed in the measured ratio of branching fractions $R_{D} = B (B \to D τ ν) / B (B \to D l ν)$ and $R_{D^{*}} = B (B \to D^{*} τ ν) / B (B \to D^{*} l ν)$ , where $l = (e, μ)$ , is more pronounced and the combined excess currently stands at $3.9 σ$ level. If it persists and confirmed by future experiments, it would be a definite hint of new physics. In this context, we consider $B_{c} \to η_{c} l ν$ and $B_{c} \to J /Ψ l ν$ decays mediated via $b \to c l ν$ charged current interactions and employ the most general effective Lagrangian in the presence of new physics to give prediction on various observables such as ratio of branching ratio, tau polarization fraction, and forward backward asymmetry for these decay modes.
hep-phPRD(2017)·101 citations
15*
Dark Photon Search at A Circular $e^{+} e^{-}$ Collider
Min He🇨🇳 · Xiao-Gang He🇹🇼 · Cheng-Kai Huang🇹🇼
One of the interesting portals linking a dark sector and the standard model (SM) is the kinetic mixing between the SM $U (1)_{Y}$ field with a new dark photon $A^{'}$ from a $U (1)_{A^{'}}$ gauge interaction. Stringent limits have been obtained for the kinetic mixing parameter $ϵ$ through various processes. In this work, we study the possibility of searching for a dark photon interaction at a circular $e^{+} e^{-}$ collider through the process $e^{+} e^{-} \to γ A^{' *} \to γ μ^{+} μ^{-}$ . We find that the constraint on $ϵ^{2}$ for dark photon mass in the few tens of GeV range, assuming that the $μ^{+} μ^{-}$ invariant mass can be measured to an accuracy of $0.5% m_{A^{'}}$ , can be better than $3 \times 1 0^{- 6}$ for the proposed CEPC with a ten-year running at 3 $σ$ (statistic) level, and better than $2 \times 1 0^{- 6}$ for FCC-ee with even just one-year running at $s = 240$ GeV, better than the LHC and other facilities can do in a similar dark photon mass range. For FCC-ee, running at $s = 160$ GeV, the constraint can be even better.
hep-phhep-exInt.J.Mod.Phys.A(2017)·22 citations
16*
Hadronic uncertainties in $B \to K^{*} μ^{+} μ^{-}$ : a state-of-the-art analysis
Bernat Capdevila (Barcelona, UAB and IFAE)🇪🇸 · Sebastien Descotes-Genon (Orsay, LPT)🇫🇷 · Lars Hofer (ICC, Barcelona U.)🇪🇸 · Joaquim Matias (Barcelona, UAB and IFAE)🇪🇸
In the absence of direct evidence for New Physics at present LHC energies, the focus is set on the anomalies and discrepancies recently observed in rare $b \to s ℓℓ$ transitions which can be interpreted as indirect hints. Global fits have shown that an economical New Physics solution can simultaneously alleviate the tensions in the various channels and can lead to a significant improvement in the description of the data. Alternative explanations within the Standard Model for part of the observed anomalies have been proposed in terms of (unexpectedly large) hadronic effects at low dilepton invariant mass and attributing tensions in protected observables to statistical fluctuations or experimental errors. We review the treatment of hadronic uncertainties in this kinematic regime for one of the most important channels, $B \to K^{*} μ^{+} μ^{-}$ , in a pedagogical way. We provide detailed arguments showing that factorisable power corrections cannot account for the observed anomalies and that an explanation through long-distance charm contributions is disfavoured. Some optimized observables at very low dilepton invariant mass are shown to be protected against contributions from the semileptonic coefficient $C_{9}$ (including any associated long-distance charm effects), enhancing their sensitivity to New Physics contributions to other Wilson coefficients. Finally, we discuss how the recent measurement of $Q_{5}$ by Belle (and in the future by LHCb and Belle-II) may provide a robust cross-check of our arguments.
hep-phhep-exJHEP(2017)·115 citations
17*
Universal Seesaw and $0 ν β β$ in new 3331 left-right symmetric model
Debasish Borah🇮🇳 · Sudhanwa Patra🇮🇳
We consider a class of left-right symmetric model with enlarged gauge group $S U (3)_{c} \times S U (3)_{L} \times S U (3)_{R} \times U (1)_{X}$ without having scalar bitriplet. In the absence of scalar bitriplet, there is no Dirac mass term for fermions including usual quarks and leptons. We introduce new isosinglet vector-like fermions so that all the fermions get their masses through a universal seesaw mechanism. We extend our discussion to neutrino mass and its implications in neutrinoless double beta decay ( $0 ν β β$ ). We show that for TeV scale $S U (3)_{R}$ gauge bosons, the heavy-light neutrino mixing contributes dominantly to $0 ν β β$ that can be observed at ongoing experiments. Towards the end we also comment on different possible symmetry breaking patterns of this enlarged gauge symmetry to that of the standard model.
hep-phPLB(2017)·8 citations
18*
The leptonic current structure and azimuthal asymmetry in deeply inelastic scattering
Hong-Fei Zhang🇨🇳 · Zhan Sun🇨🇳
We present a compact form of the leptonic currents for the computation of the processes involving an initial virtual boson (photon, $W^{\pm}$ or $Z_{0}$ ). For deeply inelastic scattering, once the azimuthal angle of the plane expanded by the initial- and final-state leptons are integrated over in the boson-proton rest frame, the azimuthal-asymmetric terms vanish, which, however, is NOT true when some physical quantities (such as the transverse momentum of the observed particle) are specified in laboratory frame. The abuse of the symmetry may lead to wrong results.
hep-phPRD(2017)·12 citations
19*
Nuclear modification of forward Drell-Yan production at the LHC
B. Ducloué🇫🇮
Forward Drell-Yan production at high energy can provide important constraints on gluon densities at small $x$ , in the saturation regime. In this work we focus on the nuclear modification of this process, which could be measured at the LHC in the near future. For this we employ the color dipole approach, using the optical Glauber model to relate the dipole cross section of a nucleus to the one of a proton. Combining these results with our earlier results for forward $J / ψ$ production, we compute the ratio of the nuclear modification factors of these two processes. This observable was recently suggested as a way to distinguish between initial and final state effects in forward particle production.
hep-phPRD(2017)·11 citations
20*
The Cosmology of Sub-MeV Dark Matter
Daniel Green🇺🇸 · Surjeet Rajendran🇺🇸
Light dark matter is a compelling experimental target in light of stringent constraints on heavier WIMPs. However, for a sub-MeV WIMP, the universe is sufficiently well understood at temperatures below 10 MeV that there is no room for it to be a thermal relic. Avoiding thermalization is itself a strong constraint with significant implications for direct detection. In this paper, we explore the space of models of sub-MeV dark matter with viable cosmologies. The parameter space of these models that is also consistent with astrophysical and lab-based limits is highly restricted for couplings to electrons but somewhat less constrained for nuclei. We find that achieving nuclear cross-sections well-above the neutrino floor necessarily predicts a new contribution to the effective number of neutrino species, $Δ N_{eff} = 0.09$ that will be tested by the next generation of CMB observations. On the other hand, models with absorption signatures of dark matter are less restricted by cosmology even with future observations.
hep-phastro-ph.COhep-thJHEP(2017)·98 citations
21*
Probing Left-Right Seesaw using Beam Polarization at an $e^{+} e^{-}$ Collider
Sudhansu S. Biswal🇮🇳 · P. S. Bhupal Dev🇺🇸
We show that the longitudinal beam polarization option at a future electron-positron collider provides an unambiguous distinction between low-scale seesaw models of neutrino mass. This is possible due to the fact that the pair production cross section of the heavy neutrinos in seesaw models is sensitive to the polarization of the initial lepton beams, and for a suitable choice of the polarization, shows a clear enhancement over the unpolarized cross section. More interestingly, the choice of the beam polarization for which the enhancement is maximum is governed by the size of the light-heavy neutrino mixing parameter. We also find that using this effect, one can probe a previously uncharted parameter space of the left-right seesaw model, which is complementary to the existing searches at both energy and intensity frontiers.
hep-phhep-exPRD(2017)·24 citations
22*
Dark sectors and enhanced $h \to τ μ$ transitions
Iftah Galon🇺🇸 · Jure Zupan🇺🇸
LHC searches with $τ$ leptons in the final state are always inclusive in missing-energy sources. A signal in the flavor-violating Higgs decay search, $h \to τ μ$ , could therefore equally well be due to a flavor conserving decay, but with an extended decay topology with additional invisible particles. We demonstrate this with the three-body decay $h \to τ μ φ$ , where $φ$ is a flavorful mediator decaying to a dark-sector. This scenario can give thermal relic dark matter that carries lepton flavor charges, a realistic structure of the charged lepton masses, and explain the anomalous magnetic moment of the muon, $(g - 2) μ$ , while simultaneously obey all indirect constraints from flavor-changing neutral currents. Another potentially observable consequence is the broadening of the collinear mass distributions in the $h \to τ μ$ searches.
hep-phhep-exJHEP(2017)·14 citations
23*
Benchmarks for Double Higgs Production in the Singlet Extended Standard Model at the LHC
Ian M. Lewis🇺🇸 · Matthew Sullivan🇺🇸
The simplest extension of the Standard Model is to add a gauge singlet scalar, $S$ : the singlet extended Standard Model. In the absence of a $Z_{2}$ symmetry $S \to - S$ and if the new scalar is sufficiently heavy, this model can lead to resonant double Higgs production, significantly increasing the production rate over the Standard Model prediction. While searches for this signal are being performed, it is important to have benchmark points and models with which to compare the experimental results. In this paper we determine these benchmarks by maximizing the double Higgs production rate at the LHC in the singlet extended Standard Model. We find that, within current constraints, the branching ratio of the new scalar into two Standard Model-like Higgs bosons can be upwards of $0.76$ , and the double Higgs rate can be increased upwards of 30 times the Standard Model prediction.
hep-phPRD(2017)·88 citations
24*
Muon g-2 and related phenomenology in constrained vector-like extensions of the MSSM
Arghya Choudhury🇬🇧 · Luc Darmé🇵🇱 · Leszek Roszkowski🇵🇱 · Enrico Maria Sessolo🇵🇱 · Sebastian Trojanowski🇺🇸
We analyze two minimal supersymmetric constrained models with low-energy vector-like matter preserving gauge coupling unification. In one we add to the MSSM spectrum a pair of 5-plets of SU(5), in the other a pair of 10-plets. We show that the muon g-2 anomaly can be explained in these models while retaining perturbativity up to the unification scale, satisfying electroweak and flavor precision tests and current LHC data. We examine also some related phenomenological features of the models, including Higgs mass, fine-tuning, dark matter and several LHC signatures. We stress that, at least for the 5-plet model, the parameter space consistent with g-2 is entirely in reach of the LHC with a moderate increase in luminosity with respect the current data set.
hep-phJHEP(2017)·36 citations
25*
Unveiling $ν$ secrets with cosmological data: neutrino masses and mass hierarchy
Sunny Vagnozzi🇸🇪 · Elena Giusarma🇺🇸 · Olga Mena🇪🇸 · Katherine Freese🇸🇪 · Martina Gerbino🇸🇪 · Shirley Ho🇺🇸 · Massimiliano Lattanzi🇮🇹
Using some of the latest cosmological datasets publicly available, we derive the strongest bounds in the literature on the sum of the three active neutrino masses, $M_{ν}$ , within the assumption of a background flat $Λ$ CDM cosmology. In the most conservative scheme, combining Planck cosmic microwave background (CMB) temperature anisotropies and baryon acoustic oscillations (BAO) data, as well as the up-to-date constraint on the optical depth to reionization ( $τ$ ), the tightest $95%$ confidence level (C.L.) upper bound we find is $M_{ν} < 0.151$ ~eV. The addition of Planck high- $ℓ$ polarization data, which however might still be contaminated by systematics, further tightens the bound to $M_{ν} < 0.118$ ~eV. A proper model comparison treatment shows that the two aforementioned combinations disfavor the IH at $\sim 64%$ ~C.L. and $\sim 71%$ ~C.L. respectively. In addition, we compare the constraining power of measurements of the full-shape galaxy power spectrum versus the BAO signature, from the BOSS survey. Even though the latest BOSS full shape measurements cover a larger volume and benefit from smaller error bars compared to previous similar measurements, the analysis method commonly adopted results in their constraining power still being less powerful than that of the extracted BAO signal. Our work uses only cosmological data; imposing the constraint $M_{ν} > 0.06 eV$ from oscillations data would raise the quoted upper bounds by $O (0.1 σ)$ and would not affect our conclusions.
↳ astro-ph.COhep-phPRD(2017)·454 citations
26*
Inflation from $(R + γ R^{n} - 2Λ)$ Gravity in Higher Dimensions
Sergei V. Ketov🇯🇵 · Hiroshi Nakada🇯🇵
We propose a derivation of the inflaton scalar potential from the higher $(D)$ dimensional $(R + γ R^{n} - 2Λ)$ gravity, with the new coupling constant $γ$ and the cosmological constant $Λ$ . We assume that a compactification of extra dimensions happened before inflation, so that the inflaton scalar potential in four spacetime dimensions appears to be dependent upon the parameters $(γ, Λ, D, n)$ . We find that consistency requires $n = D /2$ , while the dimension $D$ has to be a multiple of four. We calculate the potential for any $D$ , and determine the values of $γ$ and $Λ$ from observations. The cases of $D = 8$ and $D = 12$ are considered in more detail. Our approach results in the viable models of chaotic large-field inflation, and leads to the sharp predictions of an observable value of the tensor-to-scalar ratio $r$ of the Cosmic Microwave Background radiation.
↳ hep-thgr-qchep-phPRD(2017)·20 citations
27*
Higgs mechanism and cosmological constant in $N = 1$ supergravity with inflaton in a vector multiplet
Yermek Aldabergenov🇯🇵 · Sergei V. Ketov🇯🇵
The $N = 1$ supergravity models of cosmological inflation with inflaton belonging to a massive vector multiplet and spontaneous SUSY breaking after inflation are reformulated as the supersymmetric $U (1)$ gauge theories of a massless vector superfield interacting with the Higgs and Polonyi chiral superfields, all coupled to supergravity. The $U (1)$ gauge sector is identified with the $U (1)$ gauge fields of the super-GUT coupled to supergravity, whose gauge group has a $U (1)$ factor. A positive cosmological constant (dark energy) is included. The scalar potential is calculated, and its de Sitter vacuum solution is found to be stable.
↳ hep-thgr-qchep-phEPJC(2017)·22 citations
28*
The ideal relativistic fluid limit for a medium with polarization
David Montenegro🇧🇷 · Leonardo Tinti🇺🇸 · Giorgio Torrieri🇧🇷
We use Lagrangian effective field theory techniques to construct the equations of motion for an ideal relativistic fluid whose constituent degrees of freedom have microscopic polarization. We discuss the meaning of such a system, and argue that it is the first term in the EFT appropriate for describing polarization observables in heavy ion collisions, such as final state particle polarization and chiral magnetic and vortaic effects. We show that this system will generally require non-dissipative dynamics at higher order in gradient than second order, leading to potential stability issues known with such systems. We comment on the significance of this in the light of conjectured lower limits on viscosity.
↳ hep-thhep-phnucl-thphysics.flu-dynPRD(2017)·162 citations
29*
Derivative Expansion of Wave Function Equivalent Potentials
Takuya Sugiura🇯🇵 · Noriyoshi Ishii🇯🇵 · Makoto Oka🇯🇵
Properties of the wave function equivalent potentials introduced by HAL QCD collaboration are studied in a non-relativistic coupled-channel model. The derivative expansion is generalized, and then applied to the energy-independent and non-local potentials. The expansion coefficients are determined from analytic solutions to the Nambu-Bethe-Salpeter wave functions. The scattering phase shifts computed from these potentials are compared with the exact values to examine the convergence of the expansion. It is confirmed that the generalized derivative expansion converges in terms of the scattering phase shift rather than the functional structure of the non-local potentials. It is also found that the convergence can be improved by tuning either the choice of interpolating fields or expansion scale in the generalized derivative expansion.
↳ nucl-thhep-lathep-phPRD(2017)·5 citations
30*
On the evaluation of vortical susceptibility of chiral condensate in QCD
Ksenia Ikaeva🇷🇺
The vortical susceptibility of chiral condensate is derived in two ways. First we obtain this using the spectrum of the Dirac operator in a metric of a curved space-time, which corresponds to rotation. Second we come to the expression for the susceptibility via the holographic approach to QCD.
↳ hep-thhep-phPRD(2017)·0 citations
31*
Study of Low-Lying Baryons with Hamiltonian Effective Field Theory
Zhan-Wei Liu🇦🇺 · Jonathan M. M. Hall🇦🇺 · Waseem Kamleh🇦🇺 · Derek B. Leinweber🇦🇺 · Finn M. Stokes🇦🇺 · Anthony W. Thomas🇦🇺 · Jia-Jun Wu🇦🇺
Drawing on experimental data for baryon resonances, Hamiltonian effective field theory (HEFT) is used to predict the positions of the finite-volume energy levels to be observed in lattice QCD simulations. We have studied the low-lying baryons $N^{*} (1535)$ , $N^{*} (1440)$ , and $Λ (1405)$ . In the initial analysis, the phenomenological parameters of the Hamiltonian model are constrained by experiment and the finite-volume eigenstate energies are a prediction of the model. The agreement between HEFT predictions and lattice QCD results obtained at finite volume is excellent. These lattice results also admit a more conventional analysis where the low-energy coefficients are constrained by lattice QCD results, enabling a determination of resonance properties from lattice QCD itself. The role and importance of various components of the Hamiltonian model are examined in the finite volume. The analysis of the lattice QCD data can help us to undertand the structure of these states better.
↳ nucl-thhep-phPoS(2017)·2 citations
32*
DAMA annual modulation and mirror Dark Matter
R. Cerulli (1)🇮🇹 · P. Villar (2)🇪🇸 · F. Cappella (1)🇮🇹 · R. Bernabei (3)🇮🇹 · P. Belli (3)🇮🇹 · A. Incicchitti (4)🇮🇹 · A. Addazi (1,5)🇮🇹 · Z. Berezhiani (1,5) ((1) INFN LNGS, (2) Univ. Zaragoza and Canfranc Laboratory, (3) Univ. Roma Tor Vergata and INFN Roma Tor Vergata, (4) Univ. Roma and INFN Roma, (5) Univ. L'Aquila)🇮🇹
The DAMA experiment using ultra low background NaI(Tl) crystal scintillators has measured an annual modulation effect in the keV region which satisfies all the peculiarities of an effect induced by Dark Matter particles. In this paper we analyze this annual modulation effect in terms of mirror Dark Matter, an exact duplicate of ordinary matter from parallel hidden sector, which chemical composition is dominated by mirror helium while it can also contain significant fractions of heavier elements as Carbon and Oxygen. Dark mirror atoms are considered to interact with the target nuclei in the detector via Rutherford-like scattering induced by kinetic mixing between mirror and ordinary photons, both being massless. In the present analysis we consider various possible scenarios for the mirror matter chemical composition. For all the scenarios, the relevant ranges for the kinetic mixing parameter have been obtained taking also into account various existing uncertainties in nuclear and particle physics quantities.
↳ hep-exastro-ph.GAhep-phEPJC(2017)·69 citations
33*
Finite temperature gluon spectral functions from $N_{f} = 2 + 1 + 1$ lattice QCD
Ernst-Michael Ilgenfritz🇷🇺 · Jan M. Pawlowski🇩🇪 · Alexander Rothkopf🇩🇪 · Anton Trunin🇷🇺
We investigate gluon spectral functions at finite temperature in Landau gauge, based on a subset of lattice QCD ensembles with $N_{f} = 2 + 1 + 1$ dynamical twisted mass quarks flavors, generated by the tmfT collaboration. Our study uses a novel Bayesian approach for the extraction of non-positive definite spectral functions, which for each binned spatial momentum takes into account the gluon correlation functions at all available discrete imaginary frequencies. The spectral functions are extracted at three different lattice spacing, where for each of them, a scan of temperatures around the crossover transition is carried out at fixed scale. We find indications for the existence of a well defined quasi-particle peak. Due to a relatively small number of imaginary frequencies available, we focus on the momentum and temperature dependence of the position of this spectral feature. This dispersion relation reveals different in-medium masses for longitudinal and transversal gluons at high temperatures, qualitatively consistent with weak coupling expectations.
↳ hep-lathep-phhep-thnucl-thEPJC(2018)·32 citations
34*
Chiral extrapolation of the leading hadronic contribution to the muon anomalous magnetic moment
Maarten Golterman🇺🇸 · Kim Maltman🇦🇺 · Santiago Peris🇪🇸
A lattice computation of the leading-order hadronic contribution to the muon anomalous magnetic moment can potentially help reduce the error on the Standard Model prediction for this quantity, if sufficient control of all systematic errors affecting such a computation can be achieved. One of these systematic errors is that associated with the extrapolation to the physical pion mass from values on the lattice larger than the physical pion mass. We investigate this extrapolation assuming lattice pion masses in the range of 200 to 400MeV with the help of two-loop chiral perturbation theory, and find that such an extrapolation is unlikely to lead to control of this systematic error at the 1% level. This remains true even if various tricks to improve the reliability of the chiral extrapolation employed in the literature are taken into account. In addition, while chiral perturbation theory also predicts the dependence on the pion mass of the leading-order hadronic contribution to the muon anomalous magnetic moment as the chiral limit is approached, this prediction turns out to be of no practical use, because the physical pion mass is larger than the muon mass that sets the scale for the onset of this behavior.
↳ hep-lathep-phPRD(2017)·21 citations
35*
Stability of fundamental couplings: a global analysis
C. J. A. P. Martins🇵🇹 · A. M. M. Pinho🇵🇹
Astrophysical tests of the stability of fundamental couplings are becoming an increasingly important probe of new physics. Motivated by the recent availability of new and stronger constraints we update previous works testing the consistency of measurements of the fine-structure constant $α$ and the proton-to-electron mass ratio $μ = m_{p} / m_{e}$ (mostly obtained in the optical/ultraviolet) with combined measurements of $α$ , $μ$ and the proton gyromagnetic ratio $g_{p}$ (mostly in the radio band). We carry out a global analysis of all available data, including the 293 archival measurements of {\it Webb et al.} and 66 more recent dedicated measurements, and constraining both time and spatial variations. While nominally the full datasets show a slight statistical preference for variations of $α$ and $μ$ (at up to two standard deviations), we also find several inconsistencies between different sub-sets, likely due to hidden systematics and implying that these statistical preferences need to be taken with caution. The statistical evidence for a spatial dipole in the values of $α$ is found at the 2.3 sigma level. Forthcoming studies with facilities such as ALMA and ESPRESSO should clarify these issues.
↳ astro-ph.COgr-qchep-phhep-thPRD(2017)·30 citations
36*
Energy Transport Property of Charged Particles with Time-Dependent Damping Force via Manifold-Based Analysis Approach
Hao Zhang · Pengcheng Luo · Huifang Ding🇺🇸
This paper deals with the energy transport properties of charged particles with time-dependent damping force. Based on the proposed nonlinear dimensionless mapping,the stability and dynamical evolution of the particle system is analyzed with the help of manifold-based analysis approach.It has been found that the particle system possesses two types of energy asymptotic behaviors. More significantly, the underlying mechanism of an "energy barrier" is uncovered,i.e., one generalized invariant spanning curve emerges in the dissipative particle system. These results will be useful to enrich the energy transport behavior knowledge of the particle system.
↳ nlin.CDhep-ph0 citations
37*
Quantum Break-Time of de Sitter
Gia Dvali🇩🇪 · Cesar Gomez🇪🇸 · Sebastian Zell🇩🇪
The quantum break-time of a system is the time-scale after which its true quantum evolution departs from the classical mean field evolution. For capturing it, a quantum resolution of the classical background - e.g., in terms of a coherent state - is required. In this paper, we first consider a simple scalar model with anharmonic oscillations and derive its quantum break-time. Next, we apply these ideas to de Sitter space. We formulate a simple model of a spin-2 field, which for some time reproduces the de Sitter metric and simultaneously allows for its well-defined representation as quantum coherent state of gravitons. The mean occupation number $N$ of background gravitons turns out to be equal to the de Sitter horizon area in Planck units, while their frequency is given by the de Sitter Hubble parameter. In the semi-classical limit, we show that the model reproduces all the known properties of de Sitter, such as the redshift of probe particles and thermal Gibbons-Hawking radiation, all in the language of quantum $S$ -matrix scatterings and decays of coherent state gravitons. Most importantly, this framework allows to capture the $1/ N$ -effects to which the usual semi-classical treatment is blind. They violate the de Sitter symmetry and lead to a finite quantum break-time of the de Sitter state equal to the de Sitter radius times $N$ . We also point out that the quantum-break time is inversely proportional to the number of particle species in the theory. Thus, the quantum break-time imposes the following consistency condition: Older and species-richer universes must have smaller cosmological constants. For the maximal, phenomenologically acceptable number of species, the observed cosmological constant would saturate this bound if our Universe were $1 0^{100}$ years old in its entire classical history.
↳ hep-thastro-ph.COgr-qchep-ph+1JCAP(2017)·231 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.