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This website contains an archive of news items that previously appeared on Howard Haber's academic web page.


News items from 2017

November 30, 2017: My talk entitled Replicating the Higgs Doublet, given at Scalars 2017 at the Unversity of Warsaw in Warsaw, Poland, has been posted to Section VII of the academic website.

November 15, 2017: My paper in collaboration with Miguel Bento, J.C. Romao and Joao Silva entitled Multi-Higgs doublet models: physical parametrization, sum rules and unitarity bounds was published in the Journal of High Energy Physics (JHEP). A link to this paper can be found in Section II of the academic website.

In this work, we examine the structure of a Higgs sector consisting of N Higgs doublets. We demonstrate the good features of the so-called charged Higgs basis, which allow us to explicitly identify the physical parameters of the model. We also derive simple forms for the couplings of the Higgs bosons and vector bosons for and some of the Goldstone boson interactions. These results are applied in the derivation of Higgs coupling sum rules and tree-level unitarity bounds that restrict the size of the quartic scalar couplings.

November 6, 2017: My paper in collaboration with Sven Heinemeyer and Tim Stefaniak, entitled The Impact of Two-Loop Effects on the Scenario of MSSM Higgs Alignment without Decoupling, was published in European Physical Journal C. A link to this paper can be found in Section II of the academic website.

In this work, we assesed the impact of the leading two-loop O(αs ht2) corrections to the Higgs alignment condition in the MSSM. These corrections are sizable and important in the relevant regions of parameter space and furthermore give rise to solutions of the alignment condition that are not present in the approximate one-loop description. The implications for phenomenologically viable regions of the MSSM parameter space were considered.

September 29, 2017: My talk entitled Alignment in Models of Extended Higgs Sectors, given at the NTU workshop: "Energy Frontier in Particle Physics: LHC and Future Colliders" at National Taiwan University in Taipei, Taiwan, has been posted to Section VII of the academic website.

September 12, 2017: My talk entitled Non-minimal Higgs sectors, given at the GGI Workshop: "Collider Physics and the Cosmos" at the Galileo Galilei Institute for Theoretical Physics in Arcetri, Florence, Italy, has been posted to Section VII of the academic website.

August 31, 2017: My paper in collaboration with Miguel Bento, J.C. Romao and Joao Silva entitled Multi-Higgs doublet models: physical parametrization, sum rules and unitarity bounds, was posted today on the arXiv. A link to this paper can be found in Section II of the academic website.

In this work, we examine the structure of a Higgs sector consisting of N Higgs doublets. We show that the interactions of the gauge bosons with the physical Higgs scalars and the Goldstone bosons are determined by an N x 2N matrix. This matrix depends on (N-1)(2N-1) real parameters that are associated with the mixing of the neutral Higgs fields in the so-called charged Higgs basis. Among these parameters, N-1 are unphysical (and can be removed by rephasing the physical charged Higgs fields), and the remaining 2(N-1)2 parameters are physical. We also derive a particularly simple form for the cubic interactions and some of the quartic interactions of the Goldstone bosons with the physical Higgs scalars. These results are applied in the derivation of Higgs coupling sum rules and tree-level unitarity bounds that restrict the size of the quartic scalar couplings.

August 15, 2017: My paper in collaboration with Sven Heinemeyer and Tim Stefaniak, entitled The Impact of Two-Loop Effects on the Scenario of MSSM Higgs Alignment without Decoupling, was posted today on the arXiv. A link to this paper can be found in Section II of the academic website.

In the Higgs sector of the MSSM, alignment without decoupling is possible only in a parameter regime where there is an accidental cancellation of tree-level and radiative loop-level effects. In this paper we assess the impact of the leading two-loop O(αs ht2) corrections to the Higgs alignment condition in the MSSM. These corrections are sizable and important in the relevant regions of parameter space and furthermore give rise to solutions of the alignment condition that are not present in the approximate one-loop description. We provide a comprehensive numerical comparison of the alignment condition obtained in the approximate one-loop and two-loop approximations, and discuss its implications for phenomenologically viable regions of the MSSM parameter space.

July 16, 2017: In response to a question posed by Joao P. Silva, I have shown that an arbitrary 2n x 2n real orthogonal antisymmetric matrix can be parameterized by n(n−1) continuous angular parameters, and I ave provide an algorithm for constructing the general form for such a matrix in a set of notes entitled Parameterization of real orthogonal antisymmetric matrices. These notes have been posted to Section VI of the academic website.

June 23, 2017: My paper in collaboration with Stefania Gori and Edward Santos entitled High scale flavor alignment in two-Higgs doublet models and its phenomenology was published in the Journal of High Energy Physics (JHEP). A link to this paper can be found in Section II of the academic website.

In this paper, we considered the two Higgs doublet model (2HDM) in which flavor alignment is imposed at the Planck scale, resulting in the generation of Higgs-mediated FCNCs at the electroweak scale via renormalization group running. Using the current experimental bounds on flavor changing observables, constraints were derived on the aligned 2HDM parameter space, and its implications for Higgs boson phenomenology were analyzed.

June 15, 2017: A set of notes entitled Useful relations among the generators in the defining and adjoint representations of SU(N) has been posted to Section VI of the academic website.

June 9, 2017: In the Championship game vs. the Bad News Brewskis, Re-Entry claimed the Championship T-shirts with a riveting 15--11 victory. An eight run second inning provided a big lead early, and Re-Entry was able to withstand eight Bad News Brewskis runs over the last three innings, as their comeback fell short by four runs. With this win, Re-Entry claims a sweep with two straight softball championships over the 2016--2017 academic year. For further details, check out the UCSC Coed Softball Re-Entry Team Webpage.

Spring 2017 Coed Softball Team

May 28, 2017: My talk entitled In search of natural Higgs alignment without decoupling in the 2HDM, given at the 2nd HARMONIA Warsaw-Lisbon-Catania-Dresden meeting at the University of Warsaw in Warsaw, Poland, has been posted to Section VII of the academic website.

May 22, 2017: My talk entitled Alignment in extended Higgs models, given at PLANCK 2017 in Warsaw, Poland, has been posted to Section VII of the academic website.

March 20, 2017: My paper in collaboration with Stefania Gori and Edward Santos entitled High scale flavor alignment in two-Higgs doublet models and its phenomenology was posted today on the arXiv. A link to this paper can be found in Section II of this website.

One way to suppress Higgs-mediated flavor changing neutral currents (FCNCs) in the two Higgs doublet model (2HDM) is to demand that all Yukawa coupling matrices are diagonal when expressed in the basis of mass-eigenstate fermion fields. In this paper, we examine the 2HDM in which the flavor alignment condition is imposed at a very high energy scale. Renormalization group evolution then yields small neutral Higgs-mediated FCNCs at the electroweak scale, which can be constrained by experimental bounds on flavor changing observables. In the favored parameter region, the implications for Higgs boson phenomenology are analyzed.

March 6, 2017: My talk entitled High scale flavor-aligned 2HDM, given at the 3rd RISE Collaboration Meeting: NonMinimalHiggs in Toyama, Japan, has been posted to Section VII of the academic website.

March 1, 2017: My talk entitled A Theorist's Outlook for Higgs physics beyond the Standard Model, given at HPNP2017 in Toyama, Japan, has been posted to Section VII of the academic website.

February 3, 2017: My paper in collaboration with Philip Bechtle, Sven Heinemeyer, Tim Stefaniak, Oscar Stål, Georg Weiglein, and Lisa Zeune entitled The Light and Heavy Higgs Interpretation of the MSSM was published on my birthday in European Physical Journal C. A link to this paper can be found in Section II of the academic website.

In this paper, various MSSM interpretations of the Higgs signal at 125 GeV, in which the observed Higgs boson is identified with either the lightest or heaviest CP-even Higgs scalar of the MSSM. Regions close to the alignment limit without decoupling are still allowed and offer good prospects for upcoming LHC searches and searches at future colliders.

January 30, 2017: At the Maria Goeppert Mayer Award, Sakurai Prize Session of the April APS Meeting 2017, I gave a talk entitled Beyond the Standard Model Higgs Boson. The slides from the talk has been posted to Section VII of the academic website.

January 29, 2017: The APS prize and award winners were recognized at a ceremony held at the April APS Meeting 2017. The co-recipients of the J.J. Sakurai Prize for Theoretical Particle Physics received their awards during the APS Prizes and Awards Ceremonial Session.

APS_prize_and_award_winners

January 23, 2017: My presentation to Physics 205 can be found in Section V of the academic website.

January 10, 2017: The official writeup of my talk given at the Sixth International Workshop on the Prospects for Charged Higgs Discovery at Colliders (CHARGED 2016) in Uppsala, Sweden on October 6, 2016 has now appeared on the arXiv.   [Postscript | PDF]

January 2, 2017: The 2017 Particle Physics conference schedule has been posted to Section VIII of the academic website. Although not intended to be comprehensive, it covers many conferences that overlap with my research interests.


News items from 2016

December 16, 2016: My talk entitled High scale flavor alignment in the 2HDM and its phenomenology, given at the Helsinki Higgs Forum in Helsinki, Finland, has been posted to Section VII of the academic website.

November 18, 2016: After a season of rainouts and forfeits, Team Re-Entry finally got to play a meaningful game, as the two undefeated teams of the UCSC Coed Softball league met in the Championship game. Re-Entry dominated "Where my pitches at" with a convincing 15--2 victory in a game that was called early due to the impending darkness. The three year drought is now over, as Re-Entry claimed its eleventh championship since 1996. For further details, check out the UCSC Coed Softball Re-Entry Team Webpage.

The Fall 2016 Coed Softball Championship Re-Entry Team

November 17, 2016: Q&A: What more can we learn about the Higgs? Four physicists (myself included) discuss Higgs boson research since the discovery with Angela Anderson of Symmetry Magazine (a joint Fermilab/SLAC publication).

November 11, 2016: My talk entitled SUSY and the alignment limit, given at Higgs Couplings 2016 at SLAC has been posted to Section VII of the academic website.

October 10, 2016: The American Physical Society has announced that Gordon Kane, Howard Haber, John Gunion and Sally Dawson have been awarded the 2017 J.J. Sakurai Prize for Theoretical Particle Physics. Further details can be found at https://www.aps.org/units/dpf/awards/sakurai.cfm and at the UC Santa Cruz Newscenter.

authors of the Higgs Hunter's Guide

October 6, 2016: My talk entitled Future Higgs Studies: A Theorist’s Outlook, given at the Sixth International Workshop on the Prospects for Charged Higgs Discovery at Colliders (CHARGED 2016) in Uppsala, Sweden has been posted to Section VII of the academic website.

October 4, 2016: The 2016 edition of the Review of Particle Physics is now available on the Web. Included are the Summary Tables, Particle Listings, pdgLive and Review articles, including my updated review of Supersymmety Theory. The Review of Particle Physics is now published in the October, 2016 issue of Chinese Physics C. A hard copy of the review can be obtained here.   [PDF]

September 26, 2016: An erratum to my paper in collaboration with Pedro Ferreira and Edward Santos, entitled Preserving the validity of the Two-Higgs Doublet Model up to the Planck scale, was published today in Physical Review D. A link to the published erratum can be found in Section II of this website.

September 20, 2016: My talk entitled Alignment without decoupling in the MSSM, given at Higgs Days at Santander 2016 in Santander, Spain has been posted to Section VII of the academic website.

September 6, 2016: My talk entitled Flavor violation via Planck scale alignment in the 2HDM, given at the Workshop on Multi-Higgs Models in Lisbon, Portugal, has been posted to Section VII of the academic website.

September 2, 2016: My talk entitled Higgs Hunting 2016 Theory Summary Talk, given at Higgs Hunting 2016 in Paris, France, has been posted to Section VII of the academic website.

August 3, 2016: My paper in collaboration with Philip Bechtle, Sven Heinemeyer, Tim Stefaniak, Oscar Stål, Georg Weiglein, and Lisa Zeune entitled The Light and Heavy Higgs Interpretation of the MSSM was posted today on the arXiv. A link to this paper can be found in Section II of the academic website.

In this paper, we performed a parameter scan of the eight-parameter pMSSM taking into account the experimental Higgs boson results from Run I of the LHC as well as additional low-energy observables. We investigated various MSSM interpretations of the Higgs signal at 125 GeV, in which the observed Higgs boson is identified with either the lightest or heaviest CP-even Higgs scalar of the MSSM. We identified regions close to the alignment limit without decoupling, in which the other Higgs scalars of the MSSM can also be light, offering good prospects for upcoming LHC searches and searches at future colliders.

July 26, 2016: My paper in collaboration with Michael Dine, Patrick Draper and Laurel Stephenson Haskins entitled Perturbation Theory in Supersymmetric QED: Infrared Divergences and Gauge Invariance was posted today on the arXiv. A link to this paper can be found in Section II of the academic website.

In this paper, we investigated some aspects of the perturbation theory in N=1 supersymmetric gauge theories with massive charged matter. In general gauges, infrared divergences and nonlocal behavior arise in 1PI diagrams, associated with a 1/k4 term in the propagator for the vector superfield. We have examined this structure in supersymmetric QED. The IR divergences are gauge-dependent and must cancel in physical quantities like the electron pole mass. However, this cancellation takes place in a nontrivial way, amounting to a reorganization of the perturbative series from powers of e2 to powers of e (where e is the γe+e- coupling constant).

July 6, 2016: My talk entitled Extended Higgs sectors and the alignment limit, given at the 24rd International Conference on Supersymmetry and Unification of Fundamental Interactions (SUSY 2016) has been posted to Section VII of the academic website.

July 1, 2016: Today I gave the last of three lectures entitled SM and SUSY Higgs at pre-SUSY 2016 in Melbourne, Australia. Links to the PDF slides of the three lectures can be found in Section VII of the academic website.

June 21, 2016: My paper in collaboration with Patrick Draper and Josh Ruderman entitled Partially Natural Two Higgs Doublet Models was published today in the Journal of High Energy Physics (JHEP). This paper examines the number of independent fine-tunings required in the two Higgs doublet model (2HDM) and demonstrates under what circumstances the number of fine-tunings of the 2HDM can be reduced to the one fine tuning that sets the electroweak scale in the Standard Model. A link to this paper can be found in Section II of this website.

June 15, 2016: Today I gave the last of four lectures entitled Supersymmetric Theory and Models at the 2016 Theoretical Advanced Study Institute (TASI 2016) in Boulder, CO. Links to the PDF slides of the four lectures can be found in Section VII of the academic website.

June 6, 2016: The erratum to my paper in collaboration with Oscal Stål entitled New LHC Benchmarks for the CP-conserving Two-Higgs-Doublet Model was published today in European Physical Journal C. A link to this erratum can be found in Section II of this website.

June 3, 2016: The Re-Entry softball team met up with the Might Shmucks in the Championship game of the UCSC Friday late afternoon coed softball league. Re-Entry came back from an eight run deficit to take a one run lead in the penultimate inning. After giving up two runs in the top of the last inning, Re-Entry attempted one last comeback. But, with the tying and winning runs on base, Re-Entry was unable to produce the game winning hit. The result was a one run loss in the Championship game for the third time since the fall of 2012. For further details, check out the UCSC Coed Softball Re-Entry Team Webpage.

Spring 2016 Coed Softball Team

May 17, 2016: A corrected version of my paper in collaboration with Oscal Stål entitled New LHC Benchmarks for the CP-conserving Two-Higgs-Doublet Model was uploaded today to the arXiv. A link to this paper can be found in Section II of this website. An official erratum will be published soon in the European Physics Journal C.

May 12, 2016: My paper in collaboration with Patrick Draper and Josh Ruderman entitled Partially Natural Two Higgs Doublet Models was posted today on the arXiv. A link to this paper can be found in Section II of the academic website.

In this paper, we consider the implications of a discovery of new light fundamental scalars other than the Standard Model Higgs boson, under the assumption that the electroweak symmetry breaking scale is fine-tuned (perhaps as a result of selection effects). In this latter case, the common wisdom is that all additional elementary scalars must be heavy. We discuss counterexamples where the Higgs boson is light because of fine-tuning, and a second scalar doublet is light because a discrete symmetry relates its mass to the mass of the Standard Model Higgs boson. Our examples require new vectorlike fermions at the electroweak scale, and the models possess a rich electroweak vacuum structure.

April 18, 2016: My talk entitled Revisiting the 2012 Higgs Wishlist, given at the KITP Workshop on Experimental Challenges for the LHC Run II has been posted to Section VII of the academic website.

February 29, 2016: My paper in collaboration with Jérémy Bernon, John F. Gunion, Yun Jiang and Sabine Kraml entitled Scrutinizing the Alignment Limit in Two-Higgs-Doublet Models. II.: mH=125 GeV was published today in Physical Review D. In this paper, we examine the theoretical structure and the phenomenological implications of the alignment regime of the 2HDM (with and without decoupling) where the couplings of the heavier of the two CP-even Higgs scalars are nearly indistinguishable from those of the Standard Model (SM) Higgs boson. Implications for Run 2 at the LHC, including expectations for observing the non-SM-like scalar states, are considered. A link to this paper can be found in Section II of the academic website.

February 19, 2016: The Particle Data Group (PDG) announces that updated PDG review articles for the 2016 edition of the Review of Particle Physics are now available at http://pdg.lbl.gov/. In particular, check out my updated review of Supersymmetry, Part I (Theory).

February 17, 2016: My paper, in collaboration with Marcela Carena, Ian Low, Nausheen Shah and Carlos Wagner, entitled Alignment limit of the NMSSM Higgs sector was published today in Physical Review D. In this paper, we identify the Higgs alignment region of the NMSSM parameter space where the observed Higgs boson is predicted to have SM-like properties. The alignment limit in the NMSSM leads to a well defined spectrum in the Higgs and Higgsino sectors, and yields a rich and interesting Higgs boson phenomenology that can be tested at the LHC. A link to this paper can be found in Section II of the academic website.

January 11, 2016: My presentation to Physics 205 can be found in Section V of the academic website.

January 3, 2016: The 2016 Particle Physics conference schedule has been posted to Section VIII of the academic website. Although not intended to be comprehensive, it covers many conferences that overlap with my research interests.


News items from 2015

December 31, 2015: My three year term as Secretary-Treasurer of the Division of Particles and Fields of the American Physical Society has now come to an end. Best of luck to my successor, Kate Scholberg!

December 6, 2015: The 1st RISE Collaboration Meeting: NonMinimalHiggs took place on December 6--8, 2015 as an adjunct to the Scalars 2015 Conference held at the University of Warsaw. I presented by vidyo link the Santa Cruz node of the RISE Collaboration     [PDF]

November 13, 2015: My paper in collaboration with Jérémy Bernon, John F. Gunion, Yun Jiang and Sabine Kraml entitled Scrutinizing the Alignment Limit in Two-Higgs-Doublet Models: Part 2: mH=125 GeV was posted today on the arXiv. A link to this paper can be found in Section II of the academic website.

In this paper, we consider CP-conserving Two-Higgs-Doublet Models (2HDMs) of Type I and Type II near the alignment limit in which the heavier of the two CP-even Higgs bosons, H, is the SM-like state of mass 125 GeV. We review the theoretical structure and analyze the phenomenological implications of this particular realization of the alignment limit, which contains at least one (and perhaps more than one) scalar Higgs state with a mass below 125 GeV. For the numerical analysis, all relevant pre-LHC constraints, constraints from the measurements of the 125 GeV Higgs signal at the LHC, as well as the most recent limits coming from searches for additional Higgs-like states are employed, and the implications for Run 2 at the LHC are elucidated.

November 2, 2015: My paper in collaboration with Marcela Carena, Ian Low, Nausheen Shah and Carlos Wagner On the Alignment Limit of the NMSSM Higgs Sector was posted today on the arXiv. A link to this paper can be found in Section II of the academic website.

In this paper, an attractive region of the NMSSM parameter space is identified in which the alignment limit is realized and the observed Higgs boson is predicted to have SM-like properties. Analytic expressions for the alignment conditions are derived and are shown to point toward a more natural region of parameter space for electroweak symmetry breaking. Moreover, the alignment limit in the NMSSM leads to a well defined spectrum in the Higgs and Higgsino sectors, and yields a rich and interesting Higgs boson phenomenology that can be tested at the LHC.

October 15, 2015: My paper in collaboration with Oscal Stål entitled New LHC Benchmarks for the CP-conserving Two-Higgs-Doublet Model was published today in European Physical Journal C. This paper presents a strategy to study the parameter space of the CP-conserving, two-Higgs-doublet Model (2HDM) with Type I or II Yukawa couplings. Benchmark points, lines and planes are established by specifying the observed Higgs boson mass and its coupling strength to vector boson pairs, the mass of the second CP-even Higgs boson, the ratio of neutral Higgs vevs, and three additional dimensionless parameters. Our benchmark scenarios capture different aspects of non-standard Higgs phenomenology that are of interest for future LHC Higgs searches. A link to this paper can be found in Section II of the academic website.

October 6, 2015: My paper in collaboration with Jérémy Bernon, John F. Gunion, Yun Jiang and Sabine Kraml entitled Scrutinizing the Alignment Limit in Two-Higgs-Doublet Models: mh=125 GeV was published today in Physical Review D. In this paper, we examine the theoretical structure and the phenomenological implications of the alignment regime of the 2HDM (with and without decoupling) where the couplings of the lighter of the two CP-even Higgs scalars are nearly indistinguishable from those of the Standard Model (SM) Higgs boson. Implications for Run 2 at the LHC, including expectations for observing the non-SM-like scalar states, are considered. A link to this paper can be found in Section II of the academic website.

August 24, 2015: My talk entitled Partially Natural Two Higgs Doublet Models, given at the 23rd International Conference on Supersymmetry and Unification of Fundamental Interactions (SUSY 2015) has been posted to Section VII of the academic website.

August 3, 2015: My paper, in collaboration with Pedro Ferreira and Edward Santos, entitled Preserving the validity of the Two-Higgs Doublet Model up to the Planck scale, was published today in Physical Review D. This paper examines the constraints on the two Higgs doublet model (2HDM) due to the stability of the scalar potential and absence of Landau poles at energy scales below the Planck scale. The parameter regimes of the 2HDM with a 125 GeV SM-like Higgs boson that are stable and perturbative up to the Planck scale yield significant constraints on the heavy scalar spectrum. A link to this paper can be found in Section II of this website.

July 16, 2015: My paper in collaboration with Oscal Stål entitled New LHC Benchmarks for the CP-conserving Two-Higgs-Doublet Model was posted today on the arXiv. A link to this paper can be found in Section II of the academic website.

In this paper, we introduce a strategy to study the parameter space of the general, CP-conserving, two-Higgs-doublet Model (2HDM) with a softly broken Z2-symmetry by means of a new hybrid basis of parameters consisting of the measured values of the mass of the observed Higgs boson and its coupling strength to vector boson pairs, the mass of the second CP-even Higgs boson, the ratio of neutral Higgs vevs, and three additional dimensionless parameters. We use these input parameters to perform numerical scans of the 2HDM parameter space, surveying the available parameter regions and analyzing the model constraints. Using these results, we define a number of benchmark scenarios that capture different aspects of non-standard Higgs phenomenology that are of interest for future LHC Higgs searches.

July 6, 2015: My paper in collaboration with Jérémy Bernon, John F. Gunion, Yun Jiang and Sabine Kraml entitled Scrutinizing the Alignment Limit in Two-Higgs-Doublet Models:Part 1: mh=125 GeV was posted today on the arXiv. A link to this paper can be found in Section II of the academic website.

In this paper, we focus on the alignment regime of the 2HDM parameter regime where the couplings of the lighter of the two CP-even Higgs scalars are nearly indistinguishable from those of the Standard Model (SM) Higgs boson. We review the theoretical structure and analyze the phenomenological implications of the alignment limit without decoupling, in which the masses of the non-SM-like Higgs scalars are not significantly larger than the SM-like Higgs boson. For the numerical analysis, we perform scans of the 2HDM parameter space, taking into account all relevant pre-LHC constraints, the latest constraints from the measurements of the 125 GeV Higgs signal at the LHC, as well as the most recent limits coming from searches for other Higgs-like states. Implications for Run 2 at the LHC, including expectations for observing the other scalar states, are considered.

July 1, 2015: An expanded version of the June 23 talk entitled, LHC Benchmarks for the CP-conserving Two-Higgs-Doublet Model was presented at an LIP seminar at the Laboratorio de Instrumentacao e Fisica Experimental de Particulas in Lisbon, Portugal. The slides from the seminar have been posted to Section VII of the academic website.

June 23, 2015: I gave a talk via vidyo to the 2HDM subgroup of the LHC Higgs Cross Section Working Group at CERN entitled LHC Benchmarks for the CP-conserving 2HDM, which has been posted to Section VII of the academic website.

June 10, 2015: Version 2 of the paper entitled Preserving the validity of the Two-Higgs Doublet Model up to the Planck scale was re-posted today on the arXiv. The revised version adds a number of references, corrects some typographical errors, and adds a clarifying footnote. A link to the revised paper can be found in Section II of this website.

June 9, 2015: My Ph.D. student Laura Fava passed her Ph.D. thesis defense. Congratulations Laura!!!

June 7, 2015: After many years of toil, we get to celebrate the new Ph.D.'s.

Congratulations to the new Ph.D.'s

May 29, 2015: Team Re-Entry's attempt to reclaim the UCSC Intramurals Coed Softball Championship just falls short when the umpires rule that the dramatic walk-off game winning two run homerun by A.J. was foul. Unable to overcome that unfathomable call, instead of celebrating the 5--4 victory, Re-Entry was on the losing end of a 4--3 heartbreaking loss to the Master Batters. For more details, click on this link.

Spring 2015 Coed Softball Team

May 28, 2015: My Ph.D. student Eddie Santos passed his Ph.D. thesis defense. Congratulations Eddie!!!

May 20, 2015: My talk entitled The Alignment Limit of the MSSM Higgs sector--the Impact of Radiative Corrections, given at the Third KUTS Workshop at LPTHE in Paris, France has been posted to Section VII of this website.

May 18, 2015: My paper in collaboration with Pedro Ferreira and Edward Santos entitled Preserving the validity of the Two-Higgs Doublet Model up to the Planck scale was posted today on the arXiv. A link to this paper can be found in Section II of this website.

In this paper, we examined the constraints on the two Higgs doublet model (2HDM) due to the stability of the scalar potential and absence of Landau poles at energy scales below the Planck scale. Using basis independent techniques, we exhibited regimes of the 2HDM parameter space with a 125 GeV SM-like Higgs boson that is stable and perturbative up to the Planck scale. Implications for the heavy scalar spectrum were presented.

April 20, 2015: My talk entitled Partially Natural Two Higgs Doublet Models, given at the 4th MCTP Spring Symposium on Higgs Boson Physics in the Standard Model and Beyond has been posted to Section VII of the academic website.

March 10, 2015: The speaker list for the SCIPP Reunion Theory Symposium is now set. The Theory Symposium will take place on UCSC campus in ISB 102 from 2--6 pm on Friday April 24, 2015. For further details, check out the SCIPP Theory Symposium webpage.

March 6, 2015: Higgs boson a la carte? Check out the article in Fermilab Today that reports on my recent paper with Marcela Carena, Ian Low, Nausheen Shah and Carlos Wagner that was published last month in Physical Review D.

February 14, 2015: My talk entitled Constraints on the alignment limit of the MSSM Higgs sector, given at the The 2nd Toyama International Workshop on "Higgs as a Probe of New Physics 2015" (HPNP2015) has been posted to Section VII of the academic website. This talk is a shorter version of the seminar that I gave in January at the Lawrence Berkeley National Laboratory (with a few minor updates).

February 3, 2015: My paper, in collaboration with Marcela Carena, Ian Low, Nausheen Shah and Carlos Wagner, entitled Complementarity between nonstandard Higgs boson searches and precision Higgs boson measurements in the MSSM was published on my birthday in Physical Review D. This paper discusses the viability of alignment without decoupling in the MSSM Higgs sector. Approximate alignment can be achieved via an accidental cancellation between tree-level and loop-level contributions. However precision Higgs data combined with the LHC search for heavier Higgs states that decay into τ+τ- already places strong constraints on this scenario. A link to this paper can be found in Section II of the academic website.

January 28, 2015: I gave a talk at Lawrence Berkeley National Laboratory entitled Constraints on the alignment limit of the MSSM Higgs sector. The slides from the talk can be found here: [PDF]

January 18, 2015: An expanded version of my notes entitled Notes on antisymmetric matrices and the pfaffian have been posted to Section VI of the academic website.

January 12, 2015: My presentation to Physics 205 can be found in Section V of the academic website.

January 7, 2015: The 2015 Particle Physics conference schedule has been posted to Section VIII of this website. Although not meant to be comprehensive, it covers many conferences that overlap with my research interests.


News items from 2014

October 31, 2014: Version 2 of the paper entitled Complementarity Between Non-Standard Higgs Searches and Precision Higgs Measurements in the MSSM was re-posted today on the arXiv. The revised version adds a short discussion on possible symmetries that may govern the alignment limit of the two-Higgs doublet model, in contrast to the case of the MSSM where the alignment limit, if present, is the result of an accidental cancellation of tree-level and loop-level contributions. A link to the revised paper can be found in Section II of this website.

October 29, 2014: The San Francisco Giants win the World Series in the deciding Game 7, with a 3--2 win over the Kansas City Royals. What an epic game! Three hours of high drama and a once in a lifetime pitching performance by Madison Bumgarner to earn a five inning save.

October 21, 2014: My paper in collaboration with Marcela Carena, Ian Low, Nausheen Shah and Carlos Wagner entitled Complementarity Between Non-Standard Higgs Searches and Precision Higgs Measurements in the MSSM was posted today on the arXiv. A link to this paper in Section II of this website.

This paper examines the conventional wisdom that the constraints of the precision Higgs data implies that additional non Standard Model (SM)--like Higgs bosons of the MSSM should be heavy, with masses larger than about 400 GeV. We demonstrate that this conclusion does not hold when the theory approaches the conditions for "alignment independent of decoupling", where the lightest CP-even Higgs boson has SM-like tree-level couplings to fermions and gauge bosons, independently of the non-standard Higgs boson masses. We find that precision Higgs measurements and direct searches are complementary, and may soon be able to probe the region of non-SM-like Higgs boson with masses below the top quark pair mass threshold of 350 GeV and low to moderate values of tan β.

September 25, 2014: My talk entitled Constraints on the alignment limit of the MSSM Higgs sector, given at the IFT Program on Physics Challenges in the face of LHC-14 at the Instituto de Fisica Teórica in Madrid, Spain has been posted to Section VII of this website. This talk updates the one of the same title given in Lisbon four weeks earlier.

September 23, 2014: My talk entitled Motivations for a stable scalar in an extended Higgs sector, given at the IFT Program on Physics Challenges in the face of LHC-14 at the Instituto de Fisica Teórica in Madrid, Spain has been posted to Section VII of the academic website.

September 9, 2014: My talk entitled 2HDM Benchmarks--Theoretical Framework, given at Higgs Days at Santander 2014 has been posted to Section VII of the academic website.

September 3, 2014: The 2014 edition of the Review of Particle Physics is now available on the Web. Included are the Summary Tables, Particle Listings, pdgLive and Review articles, including my updated review of Supersymmety Theory. The Review of Particle Physics is now published in the August, 2014 issue of Chinese Physics C. A hard copy of the review can be obtained here.   [PDF]

September 2, 2014: My talk entitled Constraints on the alignment limit of the MSSM Higgs sector, given at the Workshop on Multi-Higgs Models in Lisbon, Portugal has been posted to Section VII of the academic website.

July 22, 2014: My talk entitled Can the Hbb coupling be equal in magnitude to its SM value but opposite in sign?, given at the SUSY 2014 Conference in Manchester, UK, has been posted to Section VII of the academic website.

June 13, 2014: I gave a talk via vidyo to the Workshop of the LHC Higgs Cross Section Working Group at CERN entitled 2HDM---Report on recent activities, which has been posted to Section VII of the academic website.

June 6, 2014: Team Re-Entry's attempt to win its third consecutive UCSC Intramurals Coed Softball Championship was thwarted by Team Musashi. For more details on the 18--12 loss in the Championship game, click on this link.

Spring 2014 Coed Softball Team

June 3, 2014: My paper in collaboration with Pedro Ferreira, Rui Santos and John Gunion, entitled Probing wrong-sign Yukawa couplings at the LHC and a future linear collider was published today in Physical Review D. This paper discusses the possibility that all couplings of the recently discovered Higgs boson are close to their Standard Model values in magnitude, but the overall sign of Higgs coupling to down-type fermions is reversed as compared to its Standard Model value. Prospects for detecting this wrong-sign Yukawa coupling at the LHC and ILC are investigated. A link to this paper can be found in Section II of the academic website.

May 15, 2014: I gave a talk to the Higgs/Electroweak Symmetry Breaking and Beyond Standard Model/Cosmology joint session at the AWLC14 meeting at Fermilab entitled Probing wrong-sign Yukawa couplings, which has been posted to Section VII of the academic website.

May 12, 2014: I gave a plenary talk at the AWLC14 meeting at Fermilab entitled Higgs Physics, which has been posted to Section VII of the academic website.

April 11, 2014: A short talk entitled Some Issues for Precision Higgs Mass Computations, given via Vidyo to the KUTS Workshop (I) at the Max-Planck-Institut für Physik in Munich, has been posted to Section VII of the academic website.

March 28, 2014: My talk entitled Precision Higgs and Future Colliders given at Gunion Fest, held at the University of California, Davis, has been posted to Section VII of the academic website. Follwoing the evening banquet, I gave the after dinner talk entitled Celebating more than 30 years of friendship and collaboration, which can be found here:  [PDF | Powerpoint]

March 27, 2014: Version 2 of the paper entitled Probing wrong-sign Yukawa couplings at the LHC and a future linear collider was re-posted today on the arXiv. The revised version includes a new Appendix B, which examines whether there exist regions of the MSSM Higgs parameter space in which the hbb coupling is equal in magnitude to its Standard Model value but opposite in sign. A link to this paper can be found in Section II of the academic website.

March 20, 2014: My paper in collaboration with Pedro Ferreira, Jack Gunion and Rui Santos entitled Probing wrong-sign Yukawa couplings at the LHC and a future linear collider was posted today on the arXiv. A link to this paper can be found in Section II of the academic website.

This paper discusses the possibility that all couplings of the recently discovered Higgs boson are close to their Standard Model values in magnitude, but the overall sign of Higgs coupling to down-type fermions is reversed as compared to its Standard Model value. The possibility of achieving this in a Type-II two Higgs doublet model is demonstrated, and the prospects for detecting this wrong-sign Yukawa coupling at the LHC and ILC are investigated.

March 14, 2014: My talk at the biannual Bay Area Particle Theory Seminar, entitled Decoupling and Alignment in Light of the Higgs data, can be found here: [PDF]. It has also been posted to Section VII of the academic website.

March 9, 2014: I was interviewed on KUSP radio in Santa Cruz by Robert Pollie for his weekly radio program entitled The 7th Avenue Project: Thinking Persons' Radio. The interview focused on the Higgs boson and can be found here:   [HTML | mp3]

February 11, 2014: Howard Haber and Abraham Seiden delivered the 48th annual UCSC Faculty Research Lecture, entitled The Higgs Boson Unleashed. For further information, see this news link. The slides can be found here:     [PDF | Powerpoint]     (these are very large files of 44 MB and 63 MB respectively).

January 13, 2014: My presentation to Physics 205 can be found in Section V of the academic website.

January 8, 2014: The revised version of the Higgs Working Group Report of the Snowmass 2013 Community Planning Study was posted to the arXiv. The authors of the ILC Higgs White paper have now been included as co-authors of the Higgs Working Group report.     [PDF]

January 3, 2014: Better late than never. The official writeup of my talk given at the 2013 Toyama International Workshop on Higgs as a Probe of New Physics (HPNP2013) on February 14, 2013 has finally appeared (with a new title) on the arXiv   [Postscript | PDF]   and can be found in the Proceedings of the Workshop.


News items from 2013

December 31, 2013: The third and final revised version of the ILC Higgs White Paper has been re-posted to the arXiv [PDF].

December 25, 2013: Good Times, a weekly Santa Cruz newspaper, reports on UC Santa Cruz's top scientific breakthroughs of 2013. One of the research stories, entitled "All Hail the Higgs Boson" describes the role of SCIPP physicists in the discovery of the Higgs boson and includes quotes from yours truly.     [HTML]

December 19, 2013: The 2013 partial update for the 2014 edition of the "Reviews, Tables, Plots" section of the Review of Particle Physics by the Particle Data Group is now available here. This includes the 2013 update of my review, Supersymmetry, Part I (Theory).

December 6, 2013: Team Re-Entry wins its second consecutive UCSC Intramurals Coed Softball Championship in dominant fashion with a 26--1 victory over Team Jopo. For more details click on this link.

Fall 2013 Coed Softball Team

November 15, 2013: I gave the summary talk for the Higgs/EWSB Working Group at the International Linear Collider meeting, LCWS-2013, which was held in Japan. This talk has been posted to Section VII of the academic website.

November 12, 2013: My talk entitled The Higgs Boson: Past, Present and Future given at the 2013 Inter-Acadamy Seoul Science Forum, held in Seoul, South Korea has been posted to Section VII of the academic website.

October 23, 2013: A revised version of the ILC Higgs White Paper has been re-posted to the arXiv [PDF].

October 18, 2013: Howard Haber and Abraham Seiden have been chosen as the 2013 UCSC Founders Day Dinner Faculty Research Lecturers for their highly distinguished research records and for playing major roles in the successful search for the Higgs boson!     [HTML]

October 2, 2013: The ILC Higgs White Paper, a comprehensive review of theoretical and experimental aspects of the precision Higgs program at the International Linear Collider (ILC), has been contributed to the 2013 Snowmass Proceedings. This document has also been posted to the arXiv [PDF]. A link to the most recent version of this paper can be found in Section III of the academic website.

September 21, 2013: Pictures from the Higgs Days 2013 meeting have been posted to the Santander section of my webpage of photographs.

September 18, 2013: My talk entitled 2HDM Theory and a strategy for benchmarks given at Higgs Days 2013 in Santander, Spain has been posted to Section VII of the academic website.

September 15, 2013: My talk entitled Higgs Physics at the ILC given at Scalars 2013 in Warsaw, Poland has been posted to Section VII of the academic website.

August 26, 2013: My paper in collaboration with Patrick Draper, entitled Decoupling of the right-handed neutrino contribution to the Higgs mass in supersymmetric models, was published today in the European Physical Journal C. This paper demonstrates that the contributions from the right-handed neutrino sector to the computation of the mass of the lightest CP-even Higgs boson of the MSSM are negligibly small, as expected from the decoupling theorem (thereby disproving a suggestion in the literature that such contributions could be as large as a few GeV). A link to this paper can be found in Section II of the academic website.

July 25, 2013: My talk entitled Higgs physics--approaching the decoupling limit, given at Higgs Hunting 2013 in Orsay, France, has been posted to Section VII of the acadmeic website.

July 8, 2013: My talk entitled Decoupling and the MSSM Higgs Mass, given at the KITP workshop entitled "LHC--The First Part of the Journey," has been posted to Section VII of the academic website.

July 2, 2013: My talk entitled BSM Higgs Physics at the ILC given at the Snowmass Seattle Energy Frontier Workshop at the University of Washington in Seattle has been posted to Section VII of the academic website.

June 7, 2013: Team Re-Entry wins the Spring UCSC Intramurals Coed Softball Championship in decisive fashion with a 20--5 victory over its opponent. For more details click on this link.

Spring 2013 Coed Softball Team

May 20, 2013: My talk entitled The MSSM Higgs Mass Revisited given at the Planck 2013 Conference in Bonn has been posted to Section VII of the academic website.

May 15, 2013: My talk entitled 2HDM Benchmarks for LHC Higgs Studies for the BSM Heavy Higgs meeting at CERN updates a similar talk given last month at UC Davis. A link to this latest version has been posted to Section VII of the academic website.

April 24, 2013: My paper in collaboration with Patrick Draper, entitled Decoupling of the right-handed neutrino contribution to the Higgs mass in supersymmetric models was posted today on the arXiv. A link to this paper can be found in Section II of the academic website.

April 23, 2013: My talk entitled 2HDM Benchmarks for LHC Higgs Studies given at the HEFTI workshop on the LHC Higgs Signal at UC Davis has been posted to Section VII of the academic website.

March 22, 2013: A preliminary note entitled Toward a set of 2HDM benchmarks has been posted to Section VI of the academic website and was contributed to the LHC HXSWG BSM Heavy Higgs Meeting (listed in Section VII of the academic website).

March 12, 2013: My paper in collaboration with P.M. Ferreira, Rui Santos and Joao P. Silva investigating the viability of two near mass-degenerate Higgs bosons with a mass of about 125 GeV is now published in Physical Review D. A link to this paper is given in Section II of the academic website.

March 11, 2013: My talk entitled A Higgs Hunter's Perspective, given at the Aspen Particle Physics Winter Conference, Higgs Quo Vadis, has been posted to Section VII of the academic website.

February 25, 2013: My presentation to Physics 205 can be found in Section V of the academic website.

February 14, 2013: My talk entitled Alternative futures for the Higgs data: are we approaching or receding from the decoupling limit?, given at HPNP2013 in Toyoma, Japan, has been posted to Section VII of the academic website.

January 10, 2013: My talk entitled A Higgs Hunter's Perspective, given at the Higgs Symposium at the Higgs Centre for Theoretical Physics, University of Edinburgh, has been posted to Section VII of the academic website.

January 4--6, 2013: The Search for Fundamental Physics: Higgs Bosons & Supersymmetry, a Symposium in Honor of Michael Dine and Howard Haber on the occasion of their 60th Birthdays.


News items from 2012

December 21, 2012: My talk entitled: Workshop Summary: Revisiting the Higgs Wishlist, given at the KITP Miniprogram: Higgs Identification, has been posted to Section VII of the academic website.

December 7, 2012: My talk entitled Mass-Degenerate-Higgs Hunters Explore the Two-Higgs-Doublet Model, given at the West Coast LHC Theory meeting held at UC Riverside, can be downloaded from Section VII of the academic website.

November 29, 2012: I gave the UCSC colloquium entitled The Higgs Boson Unleashed.     [PDF | PPTX]

November 13, 2012: A preprint on two-Higgs-doublet models that can accommodate an enhanced γγ signal and a slightly different invariant mass peak in the ZZ*→4 leptons and γγ channels was posted to the arXiv. A link to this preprint is located in Section II of the academic website.

October 24, 2012: My talk on the Two-Higgs Doublet Model, presented at the 2012 ATLAS Analysis Jamboree on Higgs Searches, can be downloaded from Section VII of the academic website.

October 7, 2012: In the annual SLAC softball game, Team Research built an early sixteen run lead, and then barely held on to defeat Team Accelerator 18--17. Meanwhile, the UCSC intramural coed softball league kicks off its fall season on October 19. See Section IX of the academic website for further details.

September 18, 2012: My favorite 126 GeV interpretation, presented at Higgs Days at Santander 2012, can be downloaded from Section VII of the academic website.

August 31, 2012: My talk on the necessary conditions for spontaneous CP violation presented at the Multi-Higgs Workshop in Lisbon can be downloaded from Section VII of the academic website.

July 23--24, 2012: My two lectures entitled EWSB Basics, presented at the 40th SLAC Summer Institute, can be downloaded from Section VII of the academic website.

July 4, 2012: Search for Higgs boson reveals new particle (for further details, see the CERN update in the search for the Higgs boson).

The History of Particle Physics at the Aspen Center for Physics, by Howard Haber and Joseph Lykken

June 7, 2012: Presentation of a talk entitled "Homing in on the Higgs Boson" to the SPS Chapter at UC Santa Cruz     [PDF]

March 13, 2012: American Physical Society Viewpoint by Howard E. Haber:
Homing in on the Higgs Boson.

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haber@scipp.ucsc.edu
Last Updated: November 30, 2017