Wed·Aug 5, 2015Wednesday·August 5, 2015

1. 01*

   Bridging Soft-Hard Transport Properties of Quark-Gluon Plasmas with CUJET3.0

   Jiechen Xu🇺🇸 · Jinfeng Liao🇺🇸 · Miklos Gyulassy🇺🇸

   A new model of jet quenching in nuclear collisions, CUJET3.0, is constructed by generalizing the perturbative QCD based CUJET2.0 model to include two complementary non-perturbative features of the QCD confinement cross-over phase transition near $T_c\approx 160$ MeV: (1) the suppression of quark and gluon degrees of freedom and (2) the emergence of chromo-magnetic monopole degrees of freedom. Such a semi-Quark-Gluon-Monopole Plasma (sQGMP) microscopic scenario is tested by comparing predictions of the leading hadron nuclear modification factors, $R_{AA}^h(p_T>10GeV/c,\sqrt{s})$, and their azimuthal elliptic asymmetry $v_2^h(p_T>10GeV/c,\sqrt{s})$ with available data on $h=\pi ,D,B$ jet fragments from nuclear collisions at RHIC($\sqrt{s}=0.2$ ATeV) and LHC($\sqrt{s}$=2.76 ATeV). The sQGMP model is shown to solve the long standing $R_{AA}$ vs $v_2$ puzzle by predicting a maximum of the jet quenching parameter field $\hat{q}(E,T)/T^3$ near $T_c$. The consistency of jet quenching with observed bulk perfect fluidity is demonstrated by extrapolating the sQGMP $\hat{q}$ down to thermal energy $E\sim 3T$ scales and showing that the sQGMP shear viscosity to entropy density ratio $\eta /s\approx T^3/\hat{q}$ falls close to the unitarity bound, $1/4\pi$, in the range $(1-2)T_c$. Detailed comparisons of CUJET2.0 and CUJET3.0 reveal that the remarkably different $\hat{q}(T)$ could be consistent with the same $R_{AA}$ data and could only be distinguished by anisotropy observables. These findings demonstrate clearly the inadequacy of focusing on the jet path averaged quantity $<\hat{q}>$ as the only relevant medium property to characterize jet quenching, and point to the crucial roles of other essential factors, such as the chromo electric and magnetic composites of the plasma, the screening masses and the running couplings at multiple scales that all strongly influence jet energy loss.

   hep-phnucl-exnucl-thJHEP(2016)·162 citations
2. 02*

   Implementation of the $\mathcal{O}\left({\alpha }_t^2\right)$ MSSM Higgs-mass corrections in $\mathtt{FeynHiggs}$

   Thomas Hahn🇩🇪 · Sebastian Paßehr🇩🇪

   We describe the implementation of the two-loop Higgs-mass corrections of $\mathcal{O}\left({\alpha }_t^2\right)$ in the complex MSSM in $\mathtt{FeynHiggs}$. The program for the calculation is included in $\mathtt{FeynHiggs}$ and documented here in some detail such that it can be re-used as a template for similar calculations.

   hep-phComput.Phys.Commun.(2017)·25 citations
3. 03*

   Dark matter production through loop-induced processes at the LHC: the s-channel mediator case

   Olivier Mattelaer🇬🇧 · Eleni Vryonidou🇧🇪

   We show how studies relevant for mono-X searches at the LHC in simplified models featuring a dark matter candidate and an $s$-channel mediator can be performed within the MadGraph5_aMC@NLO framework. We focus on gluon-initiated loop-induced processes, mostly relevant to the case where the mediator couples preferentially to third generation quarks and in particular to the top quark. Our implementation allows us to study signatures at hadron colliders involving missing transverse energy plus jets or plus neutral bosons ($\gamma ,Z,H$), possibly including the effects of extra radiation by multi-parton merging and matching to the parton shower.

   hep-phEPJC(2015)·78 citations
4. 04*

   The 14 TeV LHC Takes Aim at SUSY: A No-Scale Supergravity Model for LHC Run 2

   Tianjun Li🇨🇳 · James A. Maxin🇺🇸 · Dimitri V. Nanopoulos🇺🇸 · Joel W. Walker🇺🇸

   The Supergravity model named No-Scale $\mathcal{F}$-$SU(5)$, which is based upon the flipped $SU$(5) Grand Unified Theory (GUT) with additional TeV-scale vector-like flippon multiplets, has been partially probed during the LHC Run 1 at 7-8 TeV, though the majority of its model space remains viable and should be accessible by the 13-14 TeV LHC during Run 2. The model framework possesses the rather unique capacity to provide a light CP-even Higgs boson mass in the favored 124-126 GeV window while simultaneously retaining a testably light supersymmetry (SUSY) spectrum. We summarize the outlook for No-Scale $\mathcal{F}$-$SU(5)$ at the 13-14 TeV LHC and review a promising methodology for the discrimination of its long-chain cascade decay signature. We further show that proportional dependence of all model scales upon the unified gaugino mass $M_{1/2}$ minimizes electroweak fine-tuning, allowing the $Z$-boson mass $M_Z$ to be expressed as an explicit function of $M_{1/2}$, $M_Z^2=M_Z^2(M_{1/2}^2)$, with implicit dependence upon a dimensionless ratio $c$ of the supersymmetric Higgs mixing parameter $\mu$ and $M_{1/2}$. Finally, we elucidate an empirical connection between recent scalar tensor measurements and No-Scale Supergravity cosmological models that mimic the Starobinsky model of inflation.

   hep-phhep-exPhys.Scripta(2015)·0 citations
5. 05*

   Direct and indirect signals of natural composite Higgs models

   Christoph Niehoff🇩🇪 · Peter Stangl🇩🇪 · David M. Straub🇩🇪

   We present a comprehensive numerical analysis of a four-dimensional model with the Higgs as a composite pseudo-Nambu-Goldstone boson that features a calculable Higgs potential and protective custodial and flavour symmetries to reduce electroweak fine-tuning. We employ a novel numerical technique that allows us for the first time to study constraints from radiative electroweak symmetry breaking, Higgs physics, electroweak precision tests, flavour physics, and direct LHC bounds on fermion and vector boson resonances in a single framework. We consider four different flavour symmetries in the composite sector, one of which we show to not be viable anymore in view of strong precision constraints. In the other cases, all constraints can be passed with a sub-percent electroweak fine-tuning. The models can explain the excesses recently observed in $WW$, $WZ$, $Wh$ and ${\ell }^{+}{\ell }^{-}$ resonance searches by ATLAS and CMS and the anomalies in angular observables and branching ratios of rare semi-leptonic $B$ decays observed by LHCb. Solving the $B$ physics anomalies predicts the presence of a dijet or $t\bar{t}$ resonance around 1 TeV just below the sensitivity of LHC run 1. We discuss the prospects to probe the models at run 2 of the LHC. As a side product, we identify several gaps in the searches for vector-like quarks at hadron colliders, that could be closed by reanalyzing existing LHC data.

   hep-phJHEP(2016)·60 citations
6. 06*

   Higgs Bosons in Heavy Supersymmetry with an Intermediate $m_A$

   Gabriel Lee🇮🇱 · Carlos E.M. Wagner🇺🇸

   The minimal supersymmetric standard model leads to precise predictions of the properties of the light Higgs boson degrees of freedom that depend on only a few relevant supersymmetry breaking parameters. In particular, there is an upper bound on the mass of the lightest neutral Higgs boson, which for a supersymmetric spectrum of the order of a TeV is barely above the one of the Higgs resonance recently observed at the LHC. This bound can be raised by considering a heavier supersymmetric spectrum, relaxing the tension between theory and experiment. In a previous article, we studied the predictions for the lightest CP-even Higgs mass for large values of the scalar-top and heavy Higgs boson masses. In this article we perform a similar analysis, considering also the case of a CP-odd Higgs boson mass $m_A$ of the order of the weak scale. We perform the calculation using effective theory techniques, considering a two-Higgs doublet model and a Standard Model-like theory and resumming the large logarithmic corrections that appear at scales above and below $m_A$, respectively. We calculate the mass and couplings of the lightest CP-even Higgs boson and compare our results with the ones obtained by other methods.

   hep-phhep-exPRD(2015)·124 citations
7. 07*

   Global constraints on anomalous triple gauge couplings in effective field theory approach

   Adam Falkowski🇫🇷 · Martin Gonzalez-Alonso🇫🇷 · Admir Greljo🇨🇭 · David Marzocca🇨🇭

   We present a combined analysis of LHC Higgs data (signal strengths) together with LEP-2 WW production measurements. To characterize possible deviations from the Standard Model (SM) predictions, we employ the framework of an Effective Field Theory (EFT) where the SM is extended by higher-dimensional operators suppressed by the mass scale of new physics $\Lambda$. The analysis is performed consistently at the order ${\Lambda }^{-2}$ in the EFT expansion keeping all the relevant operators. While the two data sets suffer from flat directions, together they impose stringent model-independent constraints on the anomalous triple gauge couplings. As a side product, we provide the results of the combined fit in different EFT bases.

   hep-phPRL(2016)·138 citations
8. 08*

   An Analysis of B-L=-2 Operators from Matter-Higgs Interactions in a Class of Supersymmetric SO(10) Models

   Pran Nath🇺🇸 · Raza M. Syed🇦🇪

   Recently interest in GUT baryogenesis has been resurrected due to the observation that B-violating dimension seven operators that arise in grand unified theories that also violate B-L produce baryon asymmetry that cannot be wiped out by sphaleron processes. While a general analysis of such higher dimensional operators from a bottom up approach exists in the literature, a full analysis of them derived from grand unification does not exist. In this work we present a complete analysis of B-L=-2 operators within a realistic SO(10) grand unification where the doublet-triplet splitting is automatic via a missing partner mechanism. Specifically we compute all allowed dimension five, dimension seven and dimension nine operators arising from matter-Higgs interactions. The relative strength of all the allowed B-L=-2 operators is given. Such interactions are useful in the study of neutrino masses, baryogenesis, proton decay and $n-\bar{n}$ oscillations within a common realistic grand unification framework.

   hep-phhep-thPRD(2016)·10 citations
9. 09*

   OPTIMASS: A Package for the Minimization of Kinematic Mass Functions with Constraints

   Won Sang Cho🇺🇸 · James S. Gainer🇺🇸 · Doojin Kim🇺🇸 · Sung Hak Lim🇰🇷 · Konstantin T. Matchev🇺🇸 · Filip Moortgat🇨🇭 · Luc Pape🇨🇭 · Myeonghun Park🇰🇷

   Reconstructed mass variables, such as $M_2$, $M_{2C}$, $M_T^{\star }$, and $M_{T2}^W$, play an essential role in searches for new physics at hadron colliders. The calculation of these variables generally involves constrained minimization in a large parameter space, which is numerically challenging. We provide a C++ code, OPTIMASS, which interfaces with the MINUIT library to perform this constrained minimization using the Augmented Lagrangian Method. The code can be applied to arbitrarily general event topologies and thus allows the user to significantly extend the existing set of kinematic variables. We describe this code and its physics motivation, and demonstrate its use in the analysis of the fully leptonic decay of pair-produced top quarks using the $M_2$ variables.

   hep-phhep-exJHEP(2016)·29 citations
10. 10*

    Manifestly scale-invariant regularization and quantum effective operators

    D. M. Ghilencea🇨🇭

    Scale invariant theories are often used to address the hierarchy problem, however the regularization of their quantum corrections introduces a dimensionful coupling (dimensional regularization) or scale (Pauli-Villars, etc) which break this symmetry explicitly. We show how to avoid this problem and study the implications of a manifestly scale invariant regularization in (classical) scale invariant theories. We use a dilaton-dependent subtraction function $\mu (\sigma )$ which after spontaneous breaking of scale symmetry generates the usual DR subtraction scale $\mu (⟨\sigma ⟩)$. One consequence is that "evanescent" interactions generated by scale invariance of the action in $d=4-2ϵ$ (but vanishing in $d=4$), give rise to new, finite quantum corrections. We find a (finite) correction $\Delta U(\varphi ,\sigma )$ to the one-loop scalar potential for $\varphi$ and $\sigma$, beyond the Coleman-Weinberg term. $\Delta U$ is due to an evanescent correction ($\propto ϵ$) to the field-dependent masses (of the states in the loop) which multiplies the pole ($\propto 1/ϵ$) of the momentum integral, to give a finite quantum result. $\Delta U$ contains a non-polynomial operator $\sim {\varphi }^6/{\sigma }^2$ of known coefficient and is independent of the subtraction dimensionless parameter. A more general $\mu (\varphi ,\sigma )$ is ruled out since, in their classical decoupling limit, the visible sector (of the higgs $\varphi$) and hidden sector (dilaton $\sigma$) still interact at the quantum level, thus the subtraction function must depend on the dilaton only. The method is useful in models where preserving scale symmetry at quantum level is important.

    hep-phgr-qchep-thPRD(2016)·77 citations
11. 11*

    Towards a Direct Measurement of the Quark Orbital Angular Momentum Distribution

    Simonetta Liuti🇺🇸 · Aurore Courtoy🇲🇽 · Michael Engelhardt🇺🇸 · Abha Rajan🇺🇸

    We discuss two different definitions of partonic orbital angular momentum given in the literature in terms of the Fourier transform of a Wigner distribution, $F_{14}$, and a twist three generalized parton distribution, ${\tilde{E}}_{2T}$, respectively. We derive a relation between the two definitions which reflects their specific spin and intrinsic transverse momentum/transverse space correlations as well as their gauge link structure.

    hep-phPoS(2015)·0 citations
12. 12*

    Critical behaviors near the (tri-)critical end point of QCD within the NJL model

    Ya Lu🇨🇳 · Yi-Lun Du🇨🇳 · Zhu-Fang Cui🇨🇳 · Hong-Shi Zong🇨🇳

    We investigate the dynamical chiral symmetry breaking and its restoration at finite density and temperature within the two-flavor Nambu-Jona-Lasinio model, and mainly focus on the critical behaviors near the critical end point (CEP) and tricritical point (TCP) of quantum chromodynamics. The multi-solution region of the Nambu and Wigner ones is determined in the phase diagram for the massive and massless current quark, respectively. We use the various susceptibilities to locate the CEP/TCP and then extract the critical exponents near them. Our calculations reveal that the various susceptibilities share the same critical behaviors for the physical current quark mass, while they show different features in the chiral limit.

    hep-phEPJC(2015)·40 citations
13. 13*

    Origins of Inert Higgs Doublets

    Thomas W. Kephart🇺🇸 · Tzu-Chiang Yuan🇹🇼

    We consider beyond the standard model embedding of inert Higgs doublet fields. We argue that inert Higgs doublets can arise naturally in grand unified theories where the necessary associated $Z_2$ symmetry can occur automatically. Several examples are discussed.

    hep-phNPB(2016)·12 citations
14. 14*

    Radial excitations of mesons and nucleons from QCD sum rules

    Jin-Feng Jiang🇨🇳 · Shi-Lin Zhu🇨🇳

    Within the framework QCD sum rules, we use the least square fitting method to investigate the first radial excitations of the nucleon and light mesons such as $\rho$, $K^{\ast }$, $\pi$ , $\phi$. The extracted masses of these radial excitations are consistent with the experimental data. Especially we find that the decay constant of $\pi (1300)$, which is the the first radial excitation of $\pi$, is tiny and strongly suppressed as a consequence of chiral symmetry.

    hep-phPRD(2015)·13 citations
15. 15*

    Holography and the conformal window in the Veneziano limit

    Matti Jarvinen🇫🇷

    We discuss holographic QCD in the Veneziano limit (the V-QCD models), concentrating on phenomena near the "conformal" phase transition taking place at a critical value of the ratio x = N_f/N_c. In particular, we review the results for the S-parameter, the technidilaton, and the masses of the mesons.

    hep-phhep-thInt.J.Mod.Phys.A(2017)·7 citations
16. 16*

    Precise discussion on T-asymmetry with B-meson decays

    Hiroyuki Umeeda🇯🇵 · Takuya Morozumi🇯🇵 · Hideaki Okane🇯🇵

    Through $B\bar{B}$ mixing system, one can construct an asymmetry which naively seems to be a time reversal (T) odd quantity. In this article, the two processes $(\mathrm{a})B_{-}\to \overline{B^0}$ and $(\mathrm{b})\overline{B^0}\to B_{-}$ are used to construct the event number asymmetry. The CP violation of Kaon system denoted as ${ϵ}_K$ contributes to observables and we evaluate the contribution from ${ϵ}_K$ explicitly. The asymmetry is formulated with phase convention independent parameters which are invariant under redefinition of phase of quark fields. The overall factors of the time dependent decay rates are taken into account in this article. Furthermore, we suggest conditions for the asymmetry to be a T-odd quantity. The one of such conditions arises due to the difference of overall factors which form the asymmetry.

    hep-phhep-exPoS(2015)·0 citations
17. 17*

    On the scalar potential of two-Higgs doublet models

    Indrani Chakraborty🇮🇳 · Anirban Kundu🇮🇳

    We perform a detailed analysis of the Two-Higgs Doublet Model (2HDM) potential. At the tree-level, the potential may accommodate more than one minima, one of them being the electroweak (EW) minimum where the universe lives. The parameter space allowed after the data from the Large Hadron Collider (LHC) came in almost excludes those cases where the EW vacuum is shallower than the second minimum. We extend the analysis by including terms in the 2HDM potential that break the $Z_2$ symmetry of the potential by dimension-4 operators and show that the conclusions remain unchanged. Furthermore, a one-loop analysis of the potential is performed for both cases, namely, where the $Z_2$ symmetry of the potential is broken by dimension-2 or dimension-4 operators. For quantitative analysis, we show our results for the Type-II 2HDM, qualitative results remaining the same for other 2HDMs. We find that the nature of the vacua from the tree-level analysis does not change; the EW vacuum still remains deeper.

    hep-phPRD(2015)·15 citations
18. 18*

    Radiative Linear Seesaw model, Dark Matter and $U(1{)}_{B-L}$

    Weijian Wang🇨🇳 · Zhi-Long Han🇨🇳

    In this paper we propose a radiated linear seesaw model where the naturally small term ${\mu }_L$ are generated at one-loop level and its soft-breaking of lepton number symmetry attributes to the spontaneous breaking(SSB) of B-L gauge symmetry. The value of $B-L$ charges for new particles are assigned to satisfy the anomalies cancelation. It is founded that some new particles may have exotic values of $B-L$ charge such that there exists residual $Z_2\times Z_2^{\prime }$ symmetry even after SSB of $B-L$ gauge symmetry. The $Z_2\times Z_2^{\prime }$ discrete symmetry stabilizes the these particles as dark matter candidates. In the model, two classes of inert fermions and scalars with different $B-L$ charges are introduced, leading to two-component dark matter candidates. The lepton flavor violation processes, the relic density of dark matter, the direct detection of dark matter and the phenomenology at LHC are investigated.

    hep-phPRD(2015)·96 citations
19. 19*

    Goldstone's Theorem on a Light-Like Plane

    Silas R. Beane🇺🇸

    I review various aspects of chiral symmetry and its spontaneous breaking on null planes, including the interesting manner in which Goldstone's theorem is realized and the constraints that chiral symmetry imposes on the null-plane Hamiltonians. Specializing to QCD with N massless flavors, I show that there is an interesting limit in which the chiral constraints on the null-plane Hamiltonians can be solved to give the spin-flavor algebra SU(2N), recovering a result originally found by Weinberg using different methods.

    hep-phhep-thnucl-thFew Body Syst.(2015)·1 citation
20. 20*

    Predictions for Boson-Jet Observables and Fragmentation Function Ratios from a Hybrid Strong/Weak Coupling Model for Jet Quenching

    Jorge Casalderrey-Solana🇪🇸 · Doga Can Gulhan🇺🇸 · José Guilherme Milhano🇵🇹 · Daniel Pablos🇪🇸 · Krishna Rajagopal🇺🇸

    We have previously introduced a hybrid strong/weak coupling model for jet quenching in heavy ion collisions that describes the production and fragmentation of jets at weak coupling, using PYTHIA, and describes the rate at which each parton in the jet shower loses energy as it propagates through the strongly coupled plasma, dE/dx, using an expression computed holographically at strong coupling. The model has a single free parameter that we fit to a single experimental measurement. We then confront our model with experimental data on many other jet observables, focusing here on boson-jet observables, finding that it provides a good description of present jet data. Next, we provide the predictions of our hybrid model for many measurements to come, including those for inclusive jet, dijet, photon-jet and Z-jet observables in heavy ion collisions with energy $\sqrt{s}=5.02$ ATeV coming soon at the LHC. As the statistical uncertainties on near-future measurements of photon-jet observables are expected to be much smaller than those in present data, with about an order of magnitude more photon-jet events expected, predictions for these observables are particularly important. We find that most of our pre- and post-dictions do not depend sensitively on the form we choose for the rate of energy loss dE/dx of the partons in the shower. This gives our predictions considerable robustness. To better discriminate between possible forms for the rate of energy loss, though, we must turn to intrajet observables. Here, we focus on ratios of fragmentation functions. We close with a suggestion for a particular ratio, between the fragmentation functions of inclusive and associated jets with the same kinematics in the same collisions, which is particularly sensitive to the x- and E-dependence of dE/dx, and hence may be used to learn which mechanism of parton energy loss best describes the quenching of jets.

    hep-phnucl-thJHEP(2016)·125 citations
21. 21*

    General classical and quantum-mechanical description of magnetic resonance: An application to electric-dipole-moment experiments

    Alexander J. Silenko🇧🇾

    A general theoretical description of a magnetic resonance is presented. This description is necessary for a detailed analysis of spin dynamics in electric-dipole-moment experiments in storage rings. General formulas describing a behavior of all components of the polarization vector at the magnetic resonance are obtained for an arbitrary initial polarization. These formulas are exact on condition that the nonresonance rotating field is neglected. The spin dynamics is also calculated at frequencies far from resonance with allowance for both rotating fields. A general quantum-mechanical analysis of the spin evolution at the magnetic resonance is fulfilled and the full agreement between the classical and quantum-mechanical approaches is shown. Quasimagnetic resonances for particles and nuclei moving in noncontinuous perturbing fields of accelerators and storage rings are considered. Distinguishing features of quasimagnetic resonances in storage ring electric-dipole-moment experiments are investigated in detail. The exact formulas for the effect caused by the electric dipole moment are derived. The difference between the resonance effects conditioned by the rf electric-field flipper and the rf Wien filter is found and is calculated for the first time. The existence of this difference is crucial for the establishment of a consent between analytical derivations and computer simulations and for checking spin tracking programs. Main systematical errors are considered.

    ↳ nucl-thcond-mat.otherhep-phhep-thEPJC(2017)·13 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.