Friday, 8 July 2016

SUSY 2016 Liveblog: Day Five Session Two

It's already the last session of the conference, a mixed selection of talks.

11:00 am: Belle II Physics and Construction Status, Tom Browder

Belle II is the first new collider since the LHC turned on.  Working, of course, on the intensity rather than the energy frontier.

A line of attack of interest to me is dark photons.  It's good to see efforts being made to address invisibly decaying dark photons.  Of course, that's not that new (I used projected limits in a paper several years ago) but that was based on what theorists thought could be done.

B physics is a major planned program.  Leptonic decays B to τν are a good avenue to probe the Higgs sector, in particular the presence of charged Higgs.  Amusing difference between theorists and experimentalists.  Xerxes Tata stated that type-III 2HDM is "FCNC hell"; for an experimentalist, with so many signals it's FCNC heaven!

Search signal is challenging: B decays to charged track plus nothing.  But pair produce Bs, which helps with reconstruction; only really possible at an e+e- collider.  Still, no observation yet from Belle/BaBar, only observation.  But prospective limits are still much, much better than direct searches at the LHC are likely to be.

B to D decays important as we've seen some anomalies there.  Indeed, BaBar paper from 2012 saw clear discrepancy with SM while inconsistent with any type-II 2HDM (tau fraction of decays for D and D* final states).  Current status of combined results is at 3.9σ from the SM.  Belle II can shrink the uncertainties by a factor of 4 to 5, which should resolve things one way or the other.

Asymmetries in B to Kll decays are another current interesting area.  As discussed yesterday, there is a discrepancy in the kinematic distributions.  Worth emphasising that the discrepancy lies in one of two parity-violating observables.  (There is a very mild tension in the other PV observable, the forward-backward asymmetry.)

Why should we see a discrepancy here?  Well, one think is that the loops generating this process in the SM involve the heavy particles (W, Z, t).  Also, interference could be important: linear effect.

Severable observables are seeing 4+ sigma discrepancies from the SM.  So what's the problem?  There are some theoretical issues with calculating the SM predictions.  There's some dependence on hadronic form factors that should be checked on the lattice.  Checks using HQET also continue to show need for NP.  But still need more data and theory to trust everything.

Some details on Belle II experiment/detector.  Most important point: first collisions anticipated in December 2017, with the physics run to begin late 2018.

Complementarity with direct searches interesting.  Note also probing SUSY parameter space, worth presenting results to show that.

11:30 am: The 750 GeV Anomaly, Alessandro Strumia

This looks like the talk he gave at Moriond; the slides are more optimistic than I expected.  Though the spoken part is not so much ...

Diphoton has got us excited because we don't have anything else to play with.  It cannot be systematics; experimentally and theoretically very clean.  So either a statistical fluctuation or a new particle.

Discussions of the expected stuff.  Limits include invisible channels.  The simple model with new fermions/scalars in the loops runs into problems with perturbativity.  Including DM might make things easier because you can hide stuff in invisible decays of the putative resonance.

Composite models based on quark-like bound states have the problem that you'd expect a colour octet near 750 GeV.  Other models which include some more general composite dynamics; best case is to make the resonance composite but have an elementary Higgs.  (I don't know that I agree with that.)

Ultimately the theory statement is that we need some extra charged states.  Why are they light?  There are various possibilities; SUSY, unification, scale invariance or extended gauge groups.  Ultimately it might (if we are lucky) tell us where to go.

Looking ahead, we have to find this thing in other final states; measure its spin; and identify the production mechanism.  Measuring the couplings is important; interference effects could be important.  Double production could also be very important should the state be strongly coupled.  Any extra fermions or scalars should also be looked for.

Final slide: told not to talk about rumours, but essentially tells us what we know anyway. Including plots hinting at the deficit that has been reported in new data.

12:00 pm: Outlook, Hitoshi Muryama 

I can forgive the absence of slides for the summary talk.

We haven't found what we'd hoped.  So why should we still consider SUSY?  Usual list of motivations.  But why not?  Flavour, CP problems; gravitino overproduction; proton decay; Higgs mass.

The Higgs boson is the only spin 0 particle in the SM.  It lacks context but does the most important job in the theory.  SUSY offers the "explanation" of many scalar bosons, of which only one happens to gain a tachyonic mass.  But other explanations (composites or gauge-Higgs unification) do exist.

Higgs mass is peculiar: bad for theorists but good for experimentalists.  Theorists suffer from the fact that no clear evidence; SM potential metastable, not quite consistent with SUSY, etc.  But lots of experimental channels to search.  This at least gives us a potentially powerful probe.

Divergence of masses has been seen before.  In classical electrodynamics, the quantum corrections to the mass from its own field is of the order of GeV.  There would need to be a tuning of at least 0.01% to get the correct mass.  However, quantum mechanics and the associated doubling of states (antiparticles) reduces the divergence from linear to logarithmic.  In this sense, the SUSY explanation of the Higgs mass is the same.

Another successful use of naturalness comes from inflation; why is the Universe so big, flat and entropic?  These theoretical problems were explained by inflation.

Cosmology also gives a time when things where problematic; before Cobe, people were worried about the non-observation of the CMB anisotropy.  Part of the problem is that the CMB quadropole happens to be about 1% tuned smaller than the best-fit curve, which delayed the discovery.  Perhaps we are in the same position right now.

Upper bounds on sparticles?  Mini-split arguments: DM and gauge unification.  unification puts sparticles below 100 TeV, DM requires some states at TeV.  Similarly the Higgs mass points to moderately heavy stops.  Even this sort of situation would reduce the tuning from that in the SM to about 10-4.

No sign of NP means natural and simple models are excluded.  Choice between theory complexity or fine tuning model.  Can perhaps get better SUSY models if we abandon (say) WIMP DM or unification.  Discussion of SIMPs, and their detection prospects using hidden photons.  General problem is that we have almost no idea what the DM mass should be.

Effective operator analysis of BSM physics.  Notable that while first looked at in 1980 by Weinberg, complete set of d = 6 operators only constructed three years ago.  But already we can automate this.  Possible direction for flavour physics?

Susy in the future... We shouldn't panic just yet.  We can still find things and still talk about it for some time!

SUSY 2017 Announcement

Will be held at TIFR in Mumbai in December 2017.

SUSY 2016 Liveblog: Day Five Session One

One thing that's clear in the negative category for this conference is the lack of power outlets.  I'll discuss the talks I had to see yesterday without power in the next few days.  Instead, we move on to the last day of talks, which is another half-day of plenaries.  Last night was the conference banquet, and I didn't get back to my hotel room till after 1am, so I'm a little surprised I've only missed one talk.

Thursday, 7 July 2016

SUSY 2016 Liveblog: Day Four Session Three

The first post-lunch parallel sesion, discussion of non-SUSY models.  I don't come to SUSY to talk about SUSY :)

SUSY 2016 Liveblog: Day Four Session Two

The second plenary session of the day looks at some deeper questions of theory.

SUSY 2016: Day Four Session One

I didn't try to liveblog the first few days of SUSY, which was a mistake.  It turns out that doing this really does help me focus and pay attention.  So I'm starting with Thursday, which happens to be the flavour session.

Thursday, 26 May 2016

Planck 2016

So I've been trying to run a liveblog as in previous years at Planck.  However, I am going to have to call a premature halt to it.  I have some other obligations that would interfere with taking these notes, even during the talks.  I'll try to get some general thoughts on the conference out early next week, but this will be my last post during the conference itself.  But this will be my last word this week.

Wednesday, 25 May 2016

Planck 2016 Liveblog: Day Three Session Three

I skipped the second session to do some work.  But it seems to have run quite late, with a knock-on effect that the conference lunch was delayed and so I've missed the start of the first talk this afternoon.

Planck 2016 Liveblog: Day Three Session One

Day Three already, and we have a full morning of plenary talks.  I might skip some of the afternoon talks today, as I have a lot of work to do; we'll see how I feel after lunch.  The theme for today would seem to be flavour.

Planck 2016 Liveblog: Day Two Session Four

For me, the last session of the day is BSM 3, AKA the 750 GeV session.  I'm hoping this will be more interesting for me.

Tuesday, 24 May 2016

Planck 2016 Liveblog: Day Two Session Three

Back from lunch, where I made the mistake of indulging in three glasses of wine.  Time for some hardcore BSM, I guess.

Planck 2016 Liveblog: Day Two Session Two

The first of three parallel sessions today, and I've decided on the SUSY 2 session.  Though looking at the talks, there seems to be more of a DM theme with two talks not necessarily being supersymmetric.

Planck 2016 Liveblog: Day Two Session One

We move to the second day of the conference, and the only plenary session of the day.  Which is fine by me, I like the format for the conference this year more than last year.  We have a selection of collider phenomenology talks, though the connections seem a bit limited to me.

Planck 2016 Liveblog: Day One Session Four

Last session of the day, BSM 1.

Monday, 23 May 2016

Planck 2016 Liveblog: Day One Session Three

Unlike some Plancks I've been to, here we're into the parallel sessions from day one.  First off, I've chosen to attend the Higgs I session.

Also, mostly unrelated but lunch today was the best conference food I've ever had.

Planck 2016 Liveblog: Day One Session Two

Second session of the day looks quite technical.  Thankfully, at least for me, most other plenary sessions look more phenomenological.  We're running a few minutes behind already, thanks to the first session running about 15 minutes over.

Planck 2016 Liveblog: Day One Session One

It's that time of year again, the time I write most of my posts here: Conference Season!  I skipped Pheno this year for a variety of reasons, so I'm starting things off at Planck 2016, in the city of Valencia.  I've never been to this part of Spain before, but what little of the city I've seen so far does look very nice.

Thursday, 14 April 2016

Link Round-Up

Looking through the news, I saw a surprising number of stories I could write posts on.  Rather than do them all justice, however, I'm just going to through a list of links together with a couple of sentences of commentary.

Privatised Social Service Fails

From the Guardian, we hear of systemic failures with the privatisation of the NHS ambulance service:
Hundreds of patients including people with cancer and kidney failure have missed important appointments for treatment because ambulances did not arrive to take them to hospital, after privatisation of NHS non-urgent transport services in Sussex this month.
Some elderly patients have had to wait more than five hours for ambulances and been stuck at hospital for long periods after their appointments because the transport service, now run by the private firm Coperforma, has proved so unreliable.
Patients, relatives, NHS bodies and local MPs have severely criticised the service’s performance, and a trade union representing ambulance crews said it was an “absolute shambles”. The NHS organisations that awarded the four-year, £63.5m contract have now launched an investigation.
I'm shocked, shocked I tell you to hear that privatising an important public service has lead to a drop in quality.  It's never happened before, except for all those times that it has.

Wednesday, 23 March 2016

The Amusing American Primary

By which I mean the Democratic one; the Republican side is just scary.

After Sanders lost all five states last week, he faced more calls to drop out of the race.  There's a lot of things in that statement alone that amuse me.  One is that in Illinois, Clinton and Sanders split the delegates equally; while in Missouri, Clinton won one extra delegate on the basis of 1500 votes1.  A small shift in those two elections, and there'd probably be a fair bit speculation about a Sanders comeback, for no real change in the status of the election.

Monday, 21 March 2016

The Iain Duncan Smith Saga

The fallout of the budget took an unexpected turn on Friday, when work and pensions secretary (and former leader of the opposition) Iain Duncan Smith resigned.  His stated reasons were in opposition to the continued cuts to social services that have been criticised by many, including me.  The result has been a vicious exchange between Duncan Smith and George Osbourne that, given the former's tenure as party leader, reminds me of the famous quote that being attacked by Geoffrey Howe was "like being savaged by a dead sheep".

Of course, Howe ended up bringing Thatcher down, which makes that an interesting comparison.

The other thing of note is whether Duncan Smith is being entirely honest.  Some have suggested that this is just a front, and his real disagreement is over Europe.  And it's not as if he's been opposed to cuts before, although the decision to spend £1.6 billion in corporate administration, to save £1 billion in welfare payments, suggests that perhaps he does object to having to spend less.

Moriond and 750 GeV Diphotons

So the big news of the week is that we've just had Moriond.  CMS presented a reanalysis of their 13 TeV data on the diphoton excess; this included some additional data taken with zero magnetic field, equivalent to a 10% improvement.  I heard that ATLAS pulled out of presenting a new analysis, though that's not obvious from their talk.  CMS's new result, including 8 TeV data, has a 3.4σ local significance for the excess (up from about 2.4σ).  The rumour I heard for ATLAS was 4.7σ local!!  Which may be why the pulled out, that they got a significance too high for them to put faith in it.
ATLAS (red) and CMS (blue) results, from Strumia's Moriond talk

Friday, 18 March 2016

Corbyn's Labour Ahead in the Polls

For the first time since Jeremy Corbyn's surprise victory in the Labour leadership contest, an opinion poll has them above the Tories:

A new poll has put Labour ahead of the Conservatives for the first time since Jeremy Corbyn was elected leader.
A recent poll by ICM had put the Conservatives and Labour level on 36 per cent, but some had thought this might have just been a one-off, freak result.
Sadly, as someone who likes Corbyn more than not, this is probably a feature of disaffection with the current government more than anything else.  The recent Budget announcement probably exacerbated discontent with the economy and government cuts.  And we still see large discontent with both parties, with a third of the electorate preferring someone else, most notably UKIP (spit).

Budget Time

Let's talk a little about British politics for a change.  The BBC decided the headline for their story on the new budget would be about the surprise inclusion of a "sugar tax" on soft drinks.  In a clear example of its left-wing bias, news that welfare spending would have to be cut to reduce deficits, but that there was certainly money to cut corporation tax and the top rate of capital gains, was buried in the middle of the article.

Of course, it's hard to judge what the impact of the budget will be on social inequality since last year the government decided to stop including that information.  But I'm sure there's no nefarious intent.  Why, neither Cameron nor Osborne has a mustache to twirl!  Plus, as the Hufington Post pointed out, cutting corporation tax is a major example of fixing inequality, allowing all companies to pay closer to what Google does.

Thursday, 17 March 2016


Well, I made some comments before the primary elections, so it's probably worth saying a few words about the aftermath.

Wednesday, 16 March 2016

Sort of OK Tuesday

Like many non-Americans, I've been watching the current US primaries with a certain horror; I can't bear to watch, yet neither can I look away.  The Republican party has been steadfastly advancing in the fields of xenophobia, bigotry and bullying, but it still seems barely credible that they might nominate an actual fascist.  Although, when you look at the other candidates, and especially current runner-up Ted Cruz, they're not exactly any more appealing.

Tuesday, 15 March 2016

Pi Day and why American Dates are Wrong

So it's currently "Pi Day", 14th of March or 3/14 as Americans write it.  The name comes since the first three digits of π are 3.14.  Last year got more attention than usual, as it was 3/14/15 (to go with π = 3.14159...), though including rounding you could say that this year should be more appealing.  In either case, permit me to use the occaision for a brief and somewhat pointless tirade on writing dates.